CHINHOYI UNIVERSITY OF TECHNOLOGY
SCHOOL OF ENGINEERING SCIENCES AND TECHNOLOGY
DEPARTMENT OF MECHATRONICS
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
STUDENT NAME:
TAZVIVINGA TAKURA TOBIAS
REG NUMBER:
C15125444P
SUPERVISOR:
Eng. Z. HWEJU
RESEARCH PROJECT SUBMITTED IN
PARTIAL FULLFILLMENT OF THE
BACHELOR OF ENGINEERING
HOUNORS DEGREE IN
MECHATRONICS
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
DECLARATION
I TAZVIVINGA TAKURA TOBIAS (C15125444P) do hereby declare that the research project
titled A DESIGN OF A PLC BASED SUGAR CANE FEEDING HIGHT CONTROL SYSTEM
is my own work. Where other sources have been used the statements have been paraphrased and
the information attributed to the source through referencing and when the exact words quoted, the
writing has been referenced. This project is presented in partial fulfilment of the requirements of
the award of the Bachelor of Engineering Honours Degree in Mechatronics Engineering at
Chinhoyi University of Technology, CUT. This research project has not been submitted for
examination for any degree at this or any other university. I agree that the head of department may
grant permission to external copying of this project for scholarly purposes. Publication of this
script for financial gain shall be done after my written permission.
Student: ……………………………….… Date: …………………
Supervisor: ……………………………… Date: …………………
Chairperson: …………………………….. Date: …………………
Department of Mechatronics Engineering
School of Engineering Sciences & Technology
The Chinhoyi University of Technology
Private Bag 7724
I
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
DEDICATION
This project is dedicated to my family and friends who always give me their unlimited support
and love
II
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
ACKNOWLEDGEMENTS
The author wishes to acknowledge first the undeserving love of God and unlimited mind openers
from him throughout the life cycle of the project. He also wishes to acknowledge the wonderful
works, efforts, ideas and assistance from the whole Mechatronics society at Chinhoyi University
of Technology. The author wishes to extend his gratitude to his immediate supervisor Eng. Z.
Hweju and other consultants like Eng. N. Chimwaza, Eng. P Mlambo and Eng. H Dera.
III
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
ABSTRACT
After investigating the downtime in trying to rectify chokes in sugarcane crushing and the cost for
repairing damaged mechanical components after uneven supply of sugar cane to crushing
equipment this project has introduced a concept of sugarcane feed governing to try to make the
supply of cane even and maintaining the set crush rates for maximum productivity. The governing
system incorporates pneumatic cylinders and a pointy shield moved by the cylinders to govern the
amount of cane to be crushed. The whole system is PLC based and it is done automatically.
IV
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
TABLE OF CONTENTS
DECLARATION ................................................................................................................................................ I
DEDICATION .................................................................................................................................................. II
ACKNOWLEDGEMENTS ................................................................................................................................ III
ABSTRACT..................................................................................................................................................... IV
TABLE OF CONTENTS..................................................................................................................................... V
LIST OF TABLES ........................................................................................................................................... VIII
LIST OF FIGURES ........................................................................................................................................... IX
LIST OF EQUATIONS ..................................................................................................................................... XI
TABLE OF ABBREVIATIONS AND ACRONYMS .............................................................................................. XII
CHAPTER 1: INTRODUCTION ......................................................................................................................... 1
1.1
BACKGROUND ............................................................................................................................... 1
1.2
INTRODUCTION ............................................................................................................................. 2
1.3
PROBLEM STATEMENT .................................................................................................................. 3
1.4
AIM ................................................................................................................................................ 3
1.5 OBJECTIVES ......................................................................................................................................... 3
1.6 JUSTIFICATIONS................................................................................................................................... 3
1.7 SCOPE .................................................................................................................................................. 3
1.8 UNDERLYING ENGINEERING PRINCIPLES ............................................................................................ 4
CHAPTER 2: LITERATURE REVIEW ................................................................................................................. 5
2.1 INTRODUCTION ................................................................................................................................... 5
2.2
FACTORS AND PROCESS VARIABLES CONSIDERED IN CFHCS........................................................ 5
2.2.1 CRUSH RATE ................................................................................................................................. 5
2.2.2 SPEEDS OF POWERING MOTOR ................................................................................................... 5
2.2.3 SPEEDS OF CONVEYOR BELTS ...................................................................................................... 6
2.2.4 MAXIMUM CAPACITY OF THE CANE CARRIER BELT ..................................................................... 6
2.2.5 TEMPERATURES OF DRIVE AND NON-DRIVE END OF POWERING MOTORS ............................... 7
2.2.6 CLEANING WATER FLOW RATE .................................................................................................... 7
2.3 SENSORS USED FOR CANE FEED HEIGHT CONTROL SYSTEMS ............................................................ 7
2.3.1 FLOW RATE MEASURING SENSORS.............................................................................................. 8
2.3.2 TEMPERATURE MEASURING SENSORS ...................................................................................... 11
2.3.3
ROTATIONAL SPEED MEASURING SENSORS ....................................................................... 15
V
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
2.3.4 LEVEL MEASURING SENSORS ..................................................................................................... 17
2.4 ACTUATORS USED FOR CANE FEED HEIGHT CONTROL SYSTEMS ..................................................... 20
2.4.1 SOLENOID VALVE ....................................................................................................................... 20
2.4.2 ELECTRIC MOTORS ..................................................................................................................... 21
2.4.3 PNEUMATIC/HYDRAULIC CYLINDER........................................................................................... 22
2.4.4 PNEUMATIC ACTUATOR ............................................................................................................. 23
2.5 CONTROLLERS USED FOR THE AUTOMATION PROCESS ................................................................... 25
2.5.1 PROGRAMMABLE LOGIC CONTROLLERS.................................................................................... 25
2.6 WORKING PRINCIPLES OF DIFFERENT CFHCS ................................................................................... 27
2.6.1 MANUAL LEVELLING................................................................................................................... 27
2.6.2 PROBLEMS ENCOUNTERD IN MANUAL LOADING...................................................................... 29
2.6.3 LEVELLING BY CONTROLLING FEEDER TABLE SPEED (SEMI AUTOMATED) ................................ 29
2.6.4 PROBLEMS ENCOUNTERED IN SEMI AUTOMATED SYSTEMS .................................................... 30
2.7 RESEARCH GAP .................................................................................................................................. 31
2.8 CONCLUSION ..................................................................................................................................... 31
CHAPTER 3: METHODOLOGY ...................................................................................................................... 32
3.1 INTRODUCTION ................................................................................................................................. 32
3.2 POSSIBLE SOLUTIONS ........................................................................................................................ 32
3.2.1 LEVELER ON THE FEEDER TABLE ................................................................................................ 32
3.2.2 FEED GOVERNOR ON THE CANE CARRIER.................................................................................. 33
3.3 EVALUATION OF THE POSSIBLE SOLUTIONS ..................................................................................... 34
3.3.1 DECISION MATRIX ...................................................................................................................... 34
3.4 DEVELOPMENT OF CHOSEN SOLUTION ............................................................................................ 34
3.4.1 SYSTEM WORKFLOW.................................................................................................................. 34
3.4.2 SYSTEM FLOWCHART ................................................................................................................. 35
3.4.3 PROCESS DESCRIPTION .............................................................................................................. 36
3.4.4 MECHATRONIC SYSTEM DESIGN METHODOLOGY (VDI 2206)................................................... 37
3.5 CONCLUSION ..................................................................................................................................... 78
CHAPTER 4: RESULTS AND TESTING ............................................................................................................ 79
4.1 PID CONTROLLER ALGORITHM AND RESULTS .................................................................................. 79
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS ............................................................................... 86
5.1 CONCLUSION ..................................................................................................................................... 86
5.2 RECOMMENDATIONS........................................................................................................................ 86
VI
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
CHAPTER 6: APPENDIX ................................................................................................................................ 87
6.1 MATLAB CODE FOR PID COTROLLER ................................................................................................. 87
6.2 LADDER LOGIC PROGRAM FOR THE PROCESS .................................................................................. 88
CHAPTER 7: BIBLIOGRAPHY ........................................................................................................................ 91
VII
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
LIST OF TABLES
Table 1.1 Table of abbreviations and acronyms .......................................................................... XII
Table1.2 Project Timeline ................................................... Ошибка! Закладка не определена.
Table 2.1: Temperature sensors and their properties sensitive to temperature ............................. 11
Table 3.1: Decision matrix table ................................................................................................... 34
Table 3.2: Advantages and disadvantages of double acting cylinders.......................................... 39
Table 3.3: Advantages and disadvantages of single acting cylinders ........................................... 40
Table 3.4: Decision matrix of the cylinders .................................................................................. 40
Table 3.5: Advantages and disadvantages of electro-pneumatic valve positioner ....................... 41
Table 3.6: Advantages and disadvantages of force-balance pneumatic positioner ...................... 42
Table 3.7: Decision matrix of positioners ..................................................................................... 42
Table 3.8: Advantages and disadvantages of permanent mount compressors .............................. 43
Table 3.9: Advantages and disadvantages of mobile compressors ............................................... 44
Table 3.10: Advantages and disadvantages of oiled compressors ................................................ 44
Table 3.11: Advantages and disadvantages of non-oiled compressors......................................... 44
Table 3.12: Advantages and disadvantages of gasoline compressors........................................... 44
Table 3.13: Advantages and disadvantages of electric compressors ............................................ 45
Table 3.14: Advantages and disadvantages of absolute pressure sensor ...................................... 47
Table 3.15: Advantages and disadvantages of gauge pressure sensor .......................................... 47
Table 3.16: Advantages and disadvantages of differential pressure sensor.................................. 48
Table 3.17: Decision matrix of the pressure transmitter ............................................................... 48
Table 3.18: Advantages and disadvantages of unitary PLCs ........................................................ 49
Table 3.19: Advantages and disadvantages of modular PLCs ...................................................... 49
Table 3.20: Advantages and disadvantages of rack mounted PLCs ............................................. 50
Table 3.21: Decision matrix of the PLCs...................................................................................... 50
Table 3.22: Advantages and disadvantages of direct acting solenoid valves ............................... 53
Table 3.23: Advantages and disadvantages of pilot operated solenoid valves ............................. 53
Table 3.24: Advantages and disadvantages of ball valves ............................................................ 55
Table 3.25: Advantages and disadvantages of gate valves ........................................................... 56
Table 3.26: Advantages and disadvantages of butterfly valves .................................................... 56
Table 3.27: Decision matrix of valves .......................................................................................... 56
Table 3.28: Hardware elements specifications ............................................................................. 57
Table 3.29: Electrical elements specifications .............................................................................. 58
Table 3.30: System user requirements .......................................................................................... 59
Table 3.31: Functional requirements of the system ...................................................................... 59
Table 3.32: Desired system properties .......................................................................................... 77
Table 3.33: Actual system properties............................................................................................ 78
VIII
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
LIST OF FIGURES
Fig 2.1: Illustration of Bernoulli’s principle ................................................................................... 9
Fig 2.2: Principle of operation of a magnetic flowmeter .............................................................. 10
Fig 2.3: Working principle of a Magneto-resistive rotational speed sensor ................................. 15
Fig 2.4: How an optical encoder works ........................................................................................ 17
Fig 2.5: Radar level sensors .......................................................................................................... 18
Fig 2.6: 3D level scanner .............................................................................................................. 19
Fig 2.7: Microwave level scanners ............................................................................................... 20
Fig 2.8: Pneumatic solenoid valve ................................................................................................ 21
Fig 2.9: Pneumatic cylinder .......................................................................................................... 23
Fig 2.10: Pneumatic actuator ........................................................................................................ 23
Fig 2.11: Pneumatic actuator parts................................................................................................ 24
Fig 2.12: PLC and field process link ............................................................................................ 26
Fig 2.13: Allen Bradley PLC ........................................................................................................ 26
Fig 2.14: PLC system .................................................................................................................... 27
Fig 2.15 manual levelling by front-end loaders ............................................................................ 28
Fig 2.16: Speed control joystick ................................................................................................... 29
Fig 2.17: Joystick controlled feeder table ..................................................................................... 30
Fig 3.1: Work flow of CFHCS ...................................................................................................... 35
Fig 3.2: Flowchart of CFHCS ....................................................................................................... 36
Fig 3.3: VDI 2206 Mechatronic system design model ................................................................. 38
Fig 3.4: Pneumatic Cylinder ......................................................................................................... 39
Fig 3.5: Current to pneumatic converters ..................................................................................... 41
Fig 3.6: Compressor unit............................................................................................................... 43
Fig 3.7: Compressed air service unit............................................................................................. 45
Fig 3.8: Differential pressure transmitter1 .................................................................................... 46
Fig 3.9: Programmable Logic Controller ...................................................................................... 49
Fig 3.10: Infrared proximity sensor .............................................................................................. 51
Fig 3.11: Ultrasonic sensor ........................................................................................................... 51
Fig 3.12: Solenoid Valve .............................................................................................................. 52
Fig 3.13: Switch box ..................................................................................................................... 54
Fig 3.14: Pneumatic Actuator ....................................................................................................... 54
Fig 3.15: Butterfly valve ............................................................................................................... 55
Fig 3.16: Rubber wheels and holder ............................................................................................. 57
Fig 3.17: Block diagram connection of CFHCS ........................................................................... 60
Fig 3.18: Process and Instrument Diagram of CFHCS ................................................................. 61
Fig 3.19: Governor sliding rails .................................................................................................... 61
Fig 3.20: one side of the governor sliding rails ............................................................................ 62
Fig 3.21: Pneumatic cylinder ........................................................................................................ 62
Fig 3.22: Governor Body .............................................................................................................. 63
Fig 3.23: Top view of cylinder supporting frame ......................................................................... 65
IX
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.24: Front view of cylinder supporting frame ....................................................................... 66
Fig 3.25: 3D view of the cylinder-supporting frame .................................................................... 66
Fig 3.26: X-ray view of the cylinder-supporting frame ................................................................ 67
Fig 3.27: sliding rails and cylinder support dimensions ............................................................... 67
Fig 3.28: front view of the cylinder .............................................................................................. 68
Fig 3.29: 3D view of the cylinders................................................................................................ 68
Fig 3.30: Governor Top view........................................................................................................ 69
Fig 3.31: Governor Front view ..................................................................................................... 69
Fig 3.32: Governor 3D view ......................................................................................................... 70
Fig 3.33: Governor dimensions..................................................................................................... 70
Fig 3.34: block diagram of the PLC-instruments wiring .............................................................. 71
Fig 3.35: Model of the wiring diagram ......................................................................................... 72
Fig 3.36: System’s physical model ............................................................................................... 73
Fig 3.37: System control loop ....................................................................................................... 75
Fig 3.38: Closed loop control system with unit gain .................................................................... 75
Fig 3.39: System integration ......................................................................................................... 77
Fig 4.1: PID tuning reference tracker of baseline graph and tuned graph .................................... 80
Fig4.2: Parameters and results of the baseline and tuned graphs ................................................. 81
X
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
LIST OF EQUATIONS
Equation 2.1: Synchronous speed…………………………………………………………………6
Equation 2.2: Conveyor speed…………………………………………………………………….7
Equation 2.3: Maximum speed of a synchronous motor………………………………………….7
Equation 2.4: Maximum conveyor belt capacity………………………………………………….7
Equation 2.5: Bernoulli’s equation………………………………………………………………..9
Equation 2.6: Continuity equation…………………………..…………………………………….9
Equation 2.7: Calculating volumetric flow rate………………………………………………… 10
Equation 2.8: Resistance-Temperature relationship in RTDs……………………………………13
Equation 2.9: Resistance-Temperature relationship in thermistors…...14
Equation 2.10: Calculation emissivity in IR sensors…………………………………………….15
Equation 2.11: Distance calculation in RADAR measurement systems…...................................18
Equation 2.12: Distance calculation in ultrasonic sensing devices………………………………19
Equation 2.13: Magnetic field strength calculation……………………………………………...22
Equation 3.1: Volume calculation……………………………………………………………….64
Equation 3.2: Force-Pressure relationship………………………………………………………64
Equation 3.3: Storage tank size…………………………………………………………………64
Equation 3.4: Storage tank capacity…………………………………………………………….65
Equation 3.5: Newton’s second law of motion………………………………………………….75
Equation 3.6: Laplace transform……………………………………………………..………….75
Equation 3.7: Force-damping relationship of dampers………….…………………………..….75
Equation 3.8: Transfer function…………………..…………………………………………….75
Equation 3.9: PID controller transfer function………………………………………………….75
XI
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
TABLE OF ABBREVIATIONS AND ACRONYMS
Abbreviation
Full meaning
CFHCS
Cane Feed Height Control System
PID
Proportional, integral and derivative controller
PID
Process and instrument diagram
DCS
Distributed Control System
SCADA
Supervisory Control and Data Acquisition
PLC
Programmable Logic Controller
MCC
Motor Control Centre
Table 1.1 Table of abbreviations and acronyms
XII
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
CHAPTER 1: INTRODUCTION
1.1 BACKGROUND
Green Fuel Ethanol Factory is one of the major producers of ethanol in Southern Africa. It
produces approximately 300 000 litres of ethanol per day with 99.9% alcohol strength from
fermenting sugars of sugar cane. For sugarcane crushing self-tipping trucks tip off sugar cane on
to the manually operated feeder table that is a large width platform (approximately 6 meters width
and 8 meters long) with chain drives inclined at 30. The feeder table is oriented perpendicular to a
cane carrier belt that is a series of slats joined together. The cane carrier belt moves the cane to a
feeder drum and then to a shredder where the shredder crushes the cane with the help of harmers.
Sixty harmers on a shaft each weighing approximately 37 kilograms, driven by a 1megawatt
(MW), 11-kilo volts, and liquid-resistor started, squirrel cage induction motor normally called
shredder motor that will leave the billet cane into fibre. Five mills in tandem then squeeze the fibre
extracting juice leaving a fibre called bagasse that is used as a fuel for power generation. The
bagasse is used for power generation where it will be burned in a furnace and heat up steam up to
450℃ and 45 bars, super-heated steam. The steam will be then used to turn the turbine up to a
maximum speed of 6040 rpms and generate 11kV of electricity which will be used to power the
plant and also stepped up to 33kV that will be supplied to the national grid.
Juice is extracted from the mills with sugar (sucrose) concentration around 13 brix̊ and is then
pumped to the distillery area where it will be evaporated first using exhaust steam from power
generation at 2 bars and 110 degrees Celsius temperature removing excess water increasing the
concentration of sugar to around 21 brix̊, normally called mash. Degree brix (brix), ̊Bx is the
sucrose content in an aqueous solution. The mash will be store in mash buffer tanks, 500m3
capacity, waiting fermentation using yeast in fermenter tanks of 1860m3 capacity.
The mixture (mash plus yeast) will be circulated for 36 hours using 110 kW soft started induction
motor powered centrifugal pumps maintaining temperatures between 30℃ and 32℃. After 36
hours, it will be now beer with 12% alcohol strength, which will be transferred to a beer well,
which is a beer storage tank and the beer will be ready for distillation to produce ethanol. Four
distillation columns are used to achieve 99.9% alcohol normally called anhydrous alcohol (AA).
Level transmitters, pressure temperatures, temperature transmitters, valves and pumps are used in
all the distillation columns for controlling internal pressure, level and temperature. Distillation is
a continuous process as long as exhaust steam from power generation is supplied. For dispatch
process, the AA will be pumped into containers and then denatured with 200 litres of petrol per
container and corrosion inhibiter will be added to the container after AA and petrol have been
pumped in.
1
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
For process control in the plant, a Distributed Control System (DCS) is used with each section,
boiler section, power generation section, front end/ mill section and distillery section, having its
distributed controller (programmable logic controller). The controllers are connected to field
devices like control valves, flowmeters, level transmitters, pressure transmitters, electric motors
through Device Net network and other communication channels. In addition, the distributed
controllers are linked to each other with switches and optic cables under Ethernet protocol. The
distributed controllers are then connected to the massive STRATUS server, which in it includes
the domain controller server and a historian server, and then to work stations and the engineering
station through thin manager devices. Through DCS workstations and the SCADA system, the
whole plant is visualized, operated and controlled through different network protocols like
Ethernet and Device Net® where devices, PLCs, servers and workstations are connected.
1.2 INTRODUCTION
The pre-crushing processes of cane involves the tipping off cane on the feeder table, transferring
the cane to the cane carrier and then to the feeder drum and then shredding. A feeder table has so
many designs and orientation but the one under case study is inclined at 30 degrees and is
perpendicular to the cane carrier. It is inclined at 30° rising towards the cane carrier. It is supported
with a mechanical steel structure designed to withstand heavy shocks. It has a size of 6 meters
wide and 7 meters in length. The table is provided with washing arrangement for mud removal
especially during the rainy season where the harvested sugar cane will be muddy. The arrangement
is in such a way that the water will drain through the base of the feeder table. A 75 KW motor
coupled with a gearbox powers the feeder table currently. A joystick manually controls it with
three slots corresponding to the lowest speed, average and the maximum. The company operates
24 hours a day so by shift working an attended has to feed the cane to the cane carrier, which
results in uneven levels of sugar cane in the cane carrier by human error and even tiredness during
the night. A cane carrier is a V-shaped trough with a running belt as the base of the trough made
of metal slats. The belt runs from the feeder table to the shredder. A 75KW soft started motor
coupled to a gearbox powers the chain.
Due to unevenness in the cane that is fed into the cane carrier the feeder drum sometimes chocks
or there will be lumps to mills and will alter the clearance gap between crushing rolls and even
choke the mills. The choke rectifying process usually takes about 30 minutes and then the crushing
process resumes. This reduces production rates and weekly targets by the management team.
During the night shift where there will be fewer employees compared to day shift the rectification
process may take about 45 minutes. Sugar cane unevenness also affect the feeder drum as it tries
to feed more cane to the shredder. It will be lifted up and down and ends up vibrating causing wear
and tear of mechanical parts and structures of the cane feeding system.
This script tries to solve the problem of unevenness of cane and other problems resulting from it.
Review on the methods, sensors, actuators and processors that are currently in use to solve the
same problem is discussed in chapter two of this project. The design of the chosen solution is on
chapter three followed by the results section and recommendations
2
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
1.3 PROBLEM STATEMENT
Non-uniformity of cane supply levels to the shredding and crushing equipment during sugar cane
crushing for ethanol production has led to chocking, damaging of mechanical components of the
cane crushing and shredding components as well as variable crushing rates.
1.4 AIM
To design a system that automatically controls the height/level of sugarcane in cane carrier in
relation to set crush rate
1.5 OBJECTIVES
To develop a control algorithm that will control the governor height (between 30 cm and
1.2 m) having a response time of at most two seconds
To design an electro-pneumatic powered sugarcane feed governor that retrofits on the
existing cane carrier (1m width and 1.2 m height )
To design a self-operating cane feed height control system (CFHCS) that require no
human intervention during operation
1.6 JUSTIFICATIONS
The system eliminates manual operation of feeder table since it is one of the sources of
non-uniformity of cane in the two belts.
There will be increased life span of mechanical parts of the cane crushing parts.
Constant crush rate with a little variance
Prevention of overloading of feeding, shredding and crushing equipment.
Reduced choking occurrence in sugar cane feeding and milling equipment.
Reduced stoppages caused by human errors.
1.7 SCOPE
This script will include the methodology on how the system under research will operate.
The script will include the design layout of major parts of the proposed system (sliding
rails and governor body).
3
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
The script will include verified PLC ladder logic program of the system.
The complete tested circuitry of all the devices to be used will be provided
1.8 UNDERLYING ENGINEERING PRINCIPLES
Real time monitoring and control of system parameters thus the controller should be fast
in response.
Safe circuitry of the system should be kept at its highest level to avoids short circuits and
electrocution of the user
Proper sizing of system elements including feeder table VFD
4
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
CHAPTER 2: LITERATURE REVIEW
2.1 INTRODUCTION
This section will focus on the analysis of different methods that designers made in trying to
eliminate the problem of uneven distribution of pre-crushed cane in sugar milling and ethanol
production plants. It also highlights how technological advancement has influenced the design of
systems that have a goal of reducing unevenness distribution of cane.
The guiding unexhausted questions in this literature include:
1.
2.
3.
4.
5.
What are the factors to consider when designing cane feed height systems (CFHCS)?
What are the current types of CHCS designs in the world currently?
How the current CHCS are monitored and controlled?
What are the different actuators and sensors that are being used for the CFHCS?
How do the current CFHCS operate?
2.2 FACTORS AND PROCESS VARIABLES CONSIDERED IN CFHCS
2.2.1 CRUSH RATE
This is the mass flow rate of shredded cane from the shredder on the shredded cane conveyor to
the milling tandem made of mill rolls. The standard unit of measuring this mass flow rate in the
sugar industries in tones per hour, ton/hr. To calculate the mass flow rate a weightometer or other
weighing instruments are used.
The mass flow rate or the crush rate will be the main goal for the feeding process, which the
controller always tries to achieve.
2.2.2 SPEEDS OF POWERING MOTOR
This is the speed of rotation of the motor shaft in revolutions per minute. Different methods can
be used to calculate the speed of rotation of the shaft. This speed is literally motor rated speed
(rpm) and for synchronous motors, this is the synchronous speed, which is calculated as:
𝑠=
120𝑓
…………….Equation 2.1
𝑛
Synchronous speed
Where s=synchronous speed
F= frequency (50/60 Hz)
N= number of poles of the motor
5
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
For manual calculation, the above formula calculates the speed of rotation but other devices like
optical encoders are used to calculate angular speed of the shaft. (Project, n.d.)
2.2.3 SPEEDS OF CONVEYOR BELTS
The speed of conveyor belts that are powered electrically by motors have their speeds depending
on the speed of rotation of the motor shaft. Since the speeds of rotation of electric motors without
any reducing mechanism are so high, the gear ratio is also incorporated in calculating the belt
speed.
For example, a 4-pole motor powered by a 220VAC source at 50 Hz yields a speed of 1500rpm,
which is not feasible to power a belt with that speed directly. To calculate the speed of a conveyor
belt the powering roller circumference has to be known as well as the speed out of the gearbox in
revolutions per minute. If the speed and the circumference are multiplied this will give the linear
speed of the belt. When the conveyor moves one revolution the belt will move the linear distance
equal to the circumference of the roller.
For example, if a 50: 1 gear ratio is used and a motor with synchronous speed of 1500rpm (not
including slip), the speed of the conveyor will be calculated as:
𝐶𝑠 = 𝜋𝐷 ×
1500
……….Equation 2.2
50
Conveyor speed
The fraction 1500⁄50 represents the speed of the roller in rpm.
Electric drives, variable frequency drive (VFD), are used also for motor speed reduction by
adjusting the frequency of the supply AC voltage to the one which suits the required output voltage,
different drives have output ranges of frequencies they can give as long they don’t exceed the rated
motor service factor (sf) and overloading the motor.
Using the formula of synchronous speed given above:
For a 4-pole motor with a service factor of 1.6 powered by a 525VAC power source at 50Hz and
a VFD that can change input frequency to a range of 12.5Hz to 100Hz, the speed of the rotating
shaft of the motor will be from 375 rpm to 3000Hz. Now considering the service factor the
maximum speed the motor can rotate without damaging it is
𝑀𝑎𝑥 𝑠𝑝𝑒𝑒𝑑 = 𝑠𝑓 × 𝑠𝑦𝑛𝑐ℎ 𝑠𝑝𝑒𝑒𝑑
…….Equation 2.3
Maximum speed of a synchronous motor
Which gives 2400 rpm which means for that motor the VFD has to adjust its frequency correction
to give an output in the range 12.5Hz and 80Hz which corresponds to 375 rpm and 2400 rpm
respectively.
2.2.4 MAXIMUM CAPACITY OF THE CANE CARRIER BELT
Maximum capacity of the belt is the maximum mass flow rate the belt can withstand. It is
calculated mathematically using the following formula:
6
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
𝐶=
0.08𝑊 2 𝑆𝑔
…………….Equation 2.4
5000
Maximum conveyor belt capacity
Where C= capacity in tons per hour
W= width of the belt in meters
S=belt speed in meters per hour
g= density of the material handled (Dunlop, 2009)
2.2.5 TEMPERATURES OF DRIVE AND NON-DRIVE END OF POWERING MOTORS
By the principle of conservation of energy no energy is lost but is converted into other form, the
same happens when motors are running. They change some of its energy and dissipate it as heat.
If the amount of heat generated is not monitored enough it might cause early wearing out of
mechanical components as the machine over heats. The monitoring of temperatures helps to
monitor operating conditions of a motor and if it over heats alarms will be raised and the motor
can trip as per the control program.
Different methods are employed in measuring the temperature of the motor on both sides of it,
drive end and non-drive end. Temperature dependent resistors are one of the sensors used to
measure the temperature. Normally bearing temperatures and winding temperatures will be
measured. In some cases, housing temperature is measured also.
2.2.6 CLEANING WATER FLOW RATE
This parameter is measured electronically but has to be confirmed physically if it is cleaning the
cane well removing mud from the cane. Flowmeters measure the flow rate of cleaning water. These
are analogue devices that come in different types and ways to measure the flow rate. Their principle
of operation depending on the cleaning agent that is being used for cleaning purposes. Flowmeters
use different methods for measuring flow rate thus there are two types of flowmeters, which are
mass flowmeters and volumetric flowmeters. Examples of volumetric flow meters are differential
head type that include orifice plates, venturi meters and annubar, differential area type
(Rotameters), electromagnetic flowmeter, vortex flowmeter, ultrasonic flowmeter, turbine
flowmeter and positive displacement flowmeter. Generally, two types of mass flowmeters are
Coriolis mass flowmeter and thermal mass flowmeters.
The output of the flowmeter will be an analogue signal; 4-20mA, to the controller. The controller
uses this signal for control processes including the flowrate through interlocks with the supply
pump.
2.3 SENSORS USED FOR CANE FEED HEIGHT CONTROL SYSTEMS
7
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
2.3.1 FLOW RATE MEASURING SENSORS
Measurement of fluid flow is applicable in variety of fluids with different properties and by this
variation different ways and instruments have been made as a way of measuring the flow rate of
materials from less viscous substances to gases. A number of categories are used to group different
fluid flow measurement devices. Fluids though they come in two major groups, gases and liquids,
there are fluid properties under the main classification stated earlier that will make a certain device
used for one type of fluid and cannot be used for measuring the other. As an example, measuring
flow rate of flammable gases or liquids requires intrinsically safe devices which can also be used
for measuring flow rate of non-flammable fluids but the devices for measuring non-flammable
fluids cannot be used to measure flow rate of flammable fluids. Temperature of fluid that has its
flow rate to be measured is also another factor to consider in choosing a measuring device to use.
Other factors like acidity, conductivity, viscosity and ionic composition have to be considered in
choosing a measuring device to use. However, the transducers now can be classified into the
following groups.
2.3.1.1 ANEMOMETER
An Italian art architect Battista Alberti first invented the anemometer principle in 1450 who made
the first mechanical anemometer. It had a disk, mounted perpendicular to the direction of wind.
The force of the wind caused this disk to rotate at a speed proportional to wind strength. During
operation, the wind will make the disk to incline at a certain angle as well as rotating and the angle
of inclination will be proportional to wind velocity. This was the first recorded instrument to
measure wind speed. Robert Hooke then reinvented the anemometer invented by Battista in 1709
modifying it into a more advanced machine.
2.3.1.2 DIFFERENTIAL PRESSURE OR VARIABLE AREA
Examples of differential pressure type flowmeters include the Orifice plate type, the Nozzle type
Flow meter and the Venturi type Flow meter. In this class of flow meters, an obstruction is created
in the flow path, which results in pressure drop of flowing fluid. This pressure drop will be related
with the flow rate. Assuming a turbulent flow and considering a flow channel with varying cross
sectional area at point A and B of the diagram below with velocity, area, pressure and height above
the datum. If the fluid is in compressible, the Bernoulli’s equation becomes
𝑃1
+
𝑉12
+ 𝐻1 =
𝜌
2𝑔
Bernoulli’s equation
𝑃2
𝜌
+
𝑉22
2𝑔
+ 𝐻2 (Asyiddin, 2007)
…...Equation 2.5
……...……….Equation 2.6
V1A1=V2A2
Continuity equation
8
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
For in-compressible fluids, if H1=H2,
𝑃1
𝜌
+
𝑉12
2𝑔
=
𝑃2
𝜌
+
𝑉22
2𝑔
Therefore, the volumetric flow rate is given by:
𝐴2
×√
4
2𝑔
(𝑃1 − 𝑃2)
………………………...Equation 2.7
𝜌
√1−𝛽
Calculating volumetric flow rate
Where 𝛽= ratio of the two diameters (d2/d1)
Fig 2.1 below illustrates how the Bernoulli’s equation is derived. It shows a source (pump or
reservoir) at a lower height than the sink or receiver. The channel may be of different diameters.
Q=V2A2=
Fig 2.1: Illustration of Bernoulli’s principle
(Takura, 2019)
2.3.1.3 ELECTROMAGNETIC FLOWMETER
Uses principle of inductive voltage and current in accordance with Faraday’s law of magnetism,
which states that a voltage is induced in a conductor that passes through a magnetic field.
According to Precision Controls, 2004In electromagnetic flowmeters the fluid will be acting as the
conductor and the interior surface of the flowmeter has to be non-conducting. The magnetic field
will be applied to the non-conducting interior of the metering pipe of the flowmeter and electrodes
that are perpendicular to the flow monitor the resultant voltage. The voltage produced is directly
proportional to the velocity of the fluid, which then through calculations gives us the fluid flow
rate. An illustration by fig 2.2 below shows a cross-section of an electromagnetic flowmeter
mounted on a pipe.
9
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 2.2: Principle of operation of a magnetic flowmeter
(Asyiddin, 2007)
Where induced voltage Ue= BLv
Volume flow Q= VA
Where L distance between electrodes,
V flow velocity,
A pipe cross section area,
B is the magnetic flux density and
L is the distance between the electrodes
2.3.1.3.1 ADVANTAGES
Used for slurry fluids
They can measure flow rates in both directions
2.3.1.3.2 DISADVANTAGES
Only work for conducting fluids
Electrodes are easily corroded
10
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
2.3.2 TEMPERATURE MEASURING SENSORS
Temperature is one of the standard physical variables, most often measured and controlled in
industrial processes. It is the degree of hotness or coldness of a substance or body. It may be an
independent variable where other variables depend on it hence it needs to be measured.
Temperature also can depend on other industrial variables hence it needs to be measured and
controlled. Temperature is measured and controlled for different reasons depending on the type of
industry and application, which include preventing product overheating and damage, ensuring
sterilization in chemical industries, to ensure standard operating conditions, to control chemical
reactions to name just a few. To measure temperature different kinds of sensors and transducers
are used to determine the coldness or hotness of different bodies. In the sugar and ethanol industries
temperature sensors that are used include thermocouple, RTD (Resistive temperature dependent),
optical infrared and thermistors. However, other mechanical systems are used to measure the
temperature that include liquid in glass devices and temperature gauges that make use of the
Bourdon tube principle. Several factors have to be considered when choosing a temperature sensor.
These include sensor cost, its range of operation, sensitivity, response time, repeatability, accuracy
and its ability to survive in the environment of operation. There might be a case where two or more
sensor types are applicable for example, in cooling water systems, an RTD and a non-contact
infrared (IR) detector can be used.
Each sensor has its own unique way of measuring the temperature and then transmit the output
signal as an electric signal. These different ways are summarized in the table 2.1 below
Sensor
Physical property sensitive to temperature
Thermocouple
Generates voltage
RTD
Increases resistance
Thermistor
Decreases resistance
Optical infrared
Emission of IR waves at different wavelengths
Diode reverse current
Current increases with temperature
Diode forward voltage drop
Forward voltage decreases with temperature
Table 2.1: Temperature sensors and their properties sensitive to temperature
2.3.2 1 THERMOCOUPLES
These use the thermoelectric effect to measure temperature. Thermocouples consist of two wires
made of different metal alloys that are spot-welded or crimped to each other. A cable that has a
heat-resistant outer sheath protects the two metal alloy conductors. The two junctions generate a
voltage proportional to the temperature difference between the hot and cold reference junction.
For accurate measurement, the cold junction, which is used as a reference, must not be too far from
the thermocouple to reduce significant measurement error. To reduce these errors, some systems
use a number of cold junction to ensure each thermocouple is less than an inch from the cold
junction sensor. The cold and junction terms are just but a standard names or terms because in
some cases the hot junction may be subjected to a temperature below that of the cold junction.
11
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Thermocouples are grouped depending on the metal alloys used and the measuring range thus there
are three classes of thermocouples, class 1, 2 and 3. Class 1 thermocouples have a range of -40 to
+1000°C. Class 2 thermocouples have the range -40 to +1200 °C. Class 3 thermocouples have
their accuracy apply for the range -200 to + 40,1 °C .
2.3.2 1.1 ADVANTAGES
Robust design
Higher sensor accuracy
Wide ranges
2.3.2 1.2 DISADVANTAGES
Expensive
Long reaction time
Requires exact handling
2.3.2.2 RESISTANCE TEMPERATURE DETECTORS (RTD)
These capitalize on the principle of relationship between electrical resistance of a material and
their temperatures. The two major types of these devices are the metallic devices (commonly
referred to as RTDs), and thermistors. RTD technically mean pure metal conductors. Pure metal
devices have advantages which include high accuracy and stability for long periods of time. The
most common RTD the pure Platinum made is a linear device that is there is direct relationship
between temperature and resistance. The platinum wire will be protected under a ceramic core or
a sheath material. How pure the platinum wire determines how accurate the RTD will be. There is
direct relationship between purity and accuracy. Other metals such as copper nickel and tungsten
are used as an RTD material.
The platinum type RTD or PT100 have its accuracy well within the range -270°C to +850°C and
comparing with thermistors this is a wider range. The PT100 RTD has 100Ω resistance at 0°C and
have its temperature coefficient of resistance at 0.00385 Ω/°C thus a positive coefficient meaning
direct relationship. Other types like the PT500 have 100 ohms resistance at 0°C.
RTDs depend on resistance change in a metal to determine the temperature of the environment
through the relationship below (Kharagpur, n.d.)
𝑅 = 𝑅𝜃[1 + 𝛼 (𝑇 − 𝑇𝜃 ) + 𝛽(𝑇 − 𝑇𝜃)2
…………...Equation 2.8
Resistance-Temperature relationship in RTDs
Where R= resistance at temperature T
T=temperature
Rθ= resistance at set temperature
Tθ= set/known temperature
12
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
β is a constant, usually 4000.
2.3.2.2.1 ADVANTAGES
Linear relation between resistance and temperature
They offer good stability as compared to thermistors.
They have a wider range of operating temperature (-270°C to +850°C)
They are interchangeable for a wide temperature range.
2.3.2.2.2 DISADVANTAGES
They actually have small resistance change with temperature,
Slow responses
It has self-heating problems,
There is need for an external power circuit.
2.3.2.3 THERMISTORS
Thermistors are based on resistance change in a ceramic semiconductor; the resistance drops
nonlinearly with temperature rise.
1 1
𝑅 = 𝑅𝜃𝑒𝛽(𝑇−𝑇𝜃)
…………….Equation 2.9
Resistance-Temperature relationship in thermistors
Where
R is the resistance at temperature T
Rθ is the resistance at temperature Tθ
Tθ is the reference temperature, normally room temperature
β is a constant, usually 4000.
In thermistors at there is an inverse relationship between temperature and resistance thus the device
exhibit a negative temperature coefficient. They are more accurate than RTDs with an accuracy
between 0.1° to 0.2°C over a range of 0 to 100°C working temperature. Although the devices are
small and cheap, additional work is needed to linearize the output at the same time increasing the
error of the reading. For a thermistor to work a known current has to be applied and the resultant
voltage measured. Since a thermistor is a resistor, too much current may lead to heating of the
thermistor and this will affect the accuracy of the device. Working temperature range of
thermistors are usually in the range of -80°C to +150°C. The range depends on the device’s
resolution over a wide range of temperature. (Kharagpur, n.d.)
13
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
2.3.2.2.1 ADVANTAGES
Smaller resolution.
Very short response time.
Stability.
Cheap
2.3.2.2.2 DISADVANTAGES
Non-linear relationship between temperature and resistance.
Smaller temperature ranges
Overheating problems leading to inaccuracy,
External current source is required.
2.3.2.4 INFRARED TEMPERATURE SENSORS
These are non-contact temperature sensors normally called pyrometers. They are used to measure
surface temperature of an object without contact. It is used when contact-measuring methods are
impossible or impractical like when the object is inaccessible or very hot environments where
other devices will be damaged. These kind of temperature sensors use the principle that a body
emits energy that is somehow a function of temperature and emissivity. The sensor now measure
the amount of emitted energy. The emissivity of a material depends on the microstructure, texture
composition and oxidation of a surface and is a correction factor greater than zero but less than
one. Emissivity is defined as the fraction of blackbody radiation emitted by an actual surface and
has no dimensions. The relationship between temperature, energy and emissivity is given by the
equation below
𝐸 = 𝜀𝛿𝑇 4
…………….Equation 2.10
Calculation emissivity in IR sensors
Where
• E is the emissive energy (W/m2).
• 𝜀 is the emissivity (dimensionless)
• 𝛿 = Stefan-Boltzmann constant:
• T = temperature of the object (units of K).
Infrared temperature sensors exists in three main categories that are single, dual and multiwavelength or rather single colour, two colour and multi-colour. Single wavelength sensors
measure energy at one wavelength and relate to the temperature. Emissivity has to be constant for
these devices to measure correctly. Dual-wavelength devices or two colour devices measure
temperature at two different wavelengths and then calculate their ratio thus they are called ratio
pyrometers. Multi-wavelength temperature sensors are the most complex of the three. It uses
complex electronics to integrate signals measured at different wavelengths and then determine the
temperature even with varying emissivity. (Bhatia, n.d.)
14
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
2.3.2.4.1 ADVANTAGES
Used for very high temperature environments
Non-contact devices
Portable
2.3.2.4.2 DISADVANTAGES
They are the most expensive
They are not accurate
2.3.3 ROTATIONAL SPEED MEASURING SENSORS
2.3.3.1 MAGNETO-RESISTIVE ROTATIONAL SPEED SENSOR
These measure rotational speed of a body with the magneto resistive effect. The speed
measurement is done by determining the marks generated by a ferromagnetic material like gear
tooth or a magnetized ring. The sensor will be stationary and magnetic field lines generated will
be rotating thereby producing an output signal by the bending of the magnetic field. The sensor
modules comprise of a sensor element (magneto-resistive), a permanent and the signal
conditioning circuit. Magneto-resistive rotational speed sensor can measure very small rotational
speed as small as 0 Hz. The sensor has a signal conditioning circuitry for speed measurements.
Fig 2.3 below shows how the magneto-resistive sensor works in measuring rotational speed of gear
tooth.
Fig 2.3: Working principle of a Magneto-resistive rotational
15
speed sensor
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
(Fritz Schmeißer, 1999)
2.3.3.1.1 ADVANTAGES
High sensitivity of the magneto-resistive effect
Wider operating frequency range, including zero speed detection
Insensitive to vibration
Wide operating temperature range.
2.3.3.2 OPTICAL ENCODERS
An encoder is an electronic transducer that gives a coded reading of a speed measurement thus
there are linear and shaft/ rotational encoders. Rotational encoders are used to determine the
magnitude and sometimes direction of the speed of a rotating shaft. As well as displacement.
Shaft encoders exists in two groups that are incremental and absolute encoders. For incremental
encoders the Outputs are pulses that are generated by a rotating disk on the body with speed to be
determined. Displacement will be obtained when a reference point is set on the disk. The index
pulse will be used to determine the number of full revolutions made. Absolute encoders differ from
incremental encoders in that; they have more tracks on the disk that will generate pulse trains than
in incremental encoders. The pulse trains will be equal to the number of tracks on the disk.
Optical encoders make use of an opaque disk with identical translucent circular tracks. A light
source of that produces a parallel beam of light is positioned on one side of the disk and a light
detector on the other side, which could be a photo-diode or a phototransistor.
The light source will generate a beam that will be disturbed by opaque areas of the rotating disk
thus the light detector will detect light pulses, which will result in the generation of voltage pulses
which through circuit manipulation will give angular velocity and displacement. These devices are
used in electric motors to measure the angular velocity of shafts. The inner track has one
translucent part, which gives the index or home position. The arrangement of two tracks is done
to determine the direction of rotation where in one direction one track will lead the other. The same
will happen in the opposite direction. Figure 2.4 below shows the design and structure of an optical
encoder. It comprises of a disc with two concentric tracks of equally spaced holes. (Craig, n.d.)
16
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 2.4: How an optical encoder works
(insights, 2019)
2.3.3.2.1 ADVANTAGES
High resolution
High accuracy
2.3.4 LEVEL MEASURING SENSORS
2.3.4.1 RADAR LEVEL MEASUREMENT SYSTEMS
This non-contact measuring system is used for the measurement of level in liquids and solids based
on the electromagnetic spectrum. The system include a micro-pilot which detects high frequency
radar pulses that the antenna emits to the surface of the product to be measured its level and bounce
back. The time, T, the pulses take from emission up until detection is proportional to the distance,
D, travelled thus the two are related by the following equation
𝑇
𝐷 =𝑐2
Distance calculation in RADAR measurement systems
…………….Equation 2.11
Where c= 300000 km/s that is the speed of light
Radar instruments use two major frequencies that are 6GHz and 26GHz. The latter is more
accurate than the earlier. (Endress+Hauser, n.d.)
17
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
2.3.4.1.1 ADVANTAGES
They are safe to use.
Non-contact measurement
Robust, survive in dusty and noisy environments
Wide range of operation, up to 75m
They are applicable to environments with temperatures between -200 and 450°C
Figure 2.5 below shows different models of flange-type radar level measuring sensors.
Fig 2.5: Radar level sensors
(Endress+Hauser, n.d.)
2.3.4.2 ULTRASONIC LEVEL SENSOR
These make use of sound waves to detect presence and level. They are applicable in measuring
level of both liquids and solids. The system emits sound waves towards the surface of the product
and calculates the time taken to be detected by the receiver. There will be no contact between the
device and the product to be measured. The circuitry of the sensor has a piezoelectric crystal that
converts analogue electric signals to sound waves and then converts the echoed sound waves into
analogue electric signals for further use. The time it takes for the waves to be received by the
receiver is proportional to the distance between the sensor and the surface of the liquid or solid to
be measured. They use the same principle of measurement as radar systems and the same formula
for calculating distance
𝑇
𝐷 =𝑐2
…………….Equation 2.12
Distance calculation in ultrasonic sensing devices
Where c= 300000 km/s that is the speed of light
18
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
The system gives an output analogue signal of magnitude between 4–20 mA.
Their frequency range of operation is 15 kHz to 200 kHz. The medium between sensor and surface
determines the frequency to be used. Impaired medium uses higher frequencies. (Endress+Hauser,
n.d.)
2.3.4.3 3D LEVEL SCANNER
These are multi-point non-contact level measuring devices. They measure level at many points
and produce a 3D visual mapping of its measurements. Figure 2.6 below shows how the scanner
is mounted on its environment and the results it produces after measuring the level.
2.3.4.3.1 ADVANTAGES
Penetrates through dust
Uses low frequency
Accuracy through various point measurements
No contact with the product to be measured
3Ddisplay of the level profile
Fig 2.6: 3D level scanner
(Cancoppas, 2013)
19
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
2.3.4.4 MICROWAVE LEVEL SENSORS
These measure level in liquids and bulky solids with no contact with them. The sensor consists of
a microwave emitter and receiver where a radiation beam is transmitted from the emitter through
the walls of the container to the receiver. They are applicable where contact methods are limited.
These detect the level from outside the container. The container has to be penetrable by
microwaves for this technology to be used. Figure 2.7 below shows two models of the microwave
level measuring sensors.
Fig 2.7: Microwave level scanners
(Endress+Hauser, n.d.)
2.3.4.4.1 ADVANTAGES
They are not affected by environmental conditions thus, they are applicable to harsh
conditions.
Long service life
Non-contact measurement
2.4 ACTUATORS USED FOR CANE FEED HEIGHT CONTROL SYSTEMS
2.4.1 SOLENOID VALVE
This is a digital electro-mechanical device that is used in the fluid industry for opening or closing
way of flow of the fluid. It operates with a control signal normally in volts of 0V and 24 V for
closing valve or opening it respectively. Other powering mechanisms also are used which include
mechanically powered, push button and electro-hydraulic powered solenoid valves.
20
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Solenoid valves normally exhibit two states, when the coil is energized and when the coil is at rest.
They are often used to control (open and close) digital devices like on/off valves and dampers.
This type of valve has different orientations, which include 2-way-2 positions, 3 ways-2 positions,
4 ways-2 positions. Number of ways means the number of fluid ports for supply and release and
position imply the number of states the solenoid can have. They can be stand-alone devices that
is they can be mounted a distance from the device it is controlling or the can be mounted on the
fluid ports of the devices as the one shown on fig 2.8 below.
Solenoid valves have a ferrous shaft that can move sideways opening or closing fluid ports. The
movement of the shaft is due to a coil that when it is charged with a 24V DC it will become
magnetized and attracts the ferrous shaft also compressing a spring inside the valve and releases
it when it is not energized (0V DC). For the release process the compressed spring will return to
its rest position.
Fig 2.8: Pneumatic solenoid valve
(Trimantec, 2019)
2.4.2 ELECTRIC MOTORS
These electrical devices change electromagnetic energy into mechanical energy. Electric motors
operate on the Faraday’s principle of electro-magnetism, which states that a current carrying
conductor in a magnetic field experiences a mechanical force. By Lenz’s law, the magnitude of
the induced force is directly proportional to magnetic field strength and the amount of current in
the conductor. This is given by the equation below
𝐹 = 𝛽𝐼𝐿
…………….Equation 2.13
Magnetic field strength calculation
Where:
F = Force
I = Active Current
L = Length of conductor)
21
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
𝛽= Magnetic Flux (Weber/m2)
Industrial motors are classified into three major categories that are DC motors, Synchronous
motors or induction motors. All these groups no mater different operation principles have the
same major components which are the stator, rotor and frame
2.4.2.1 DIRECT-CURRENT MOTORS
These make use of unidirectional current are used in special applications like bearing lubrication
of turbines. Due to their costs, some applications, which require DC motors, AC induction motors
with variable speed drives, are used.
2.4.2.2 SYNCHRONOUS MOTORS
These are AC powered actuators where the power is fed to the stator (stationary part) of the device
and direct current from a different source is supplied to the rotor. The magnetic field created in the
rotor locks onto the stator-rotating field and rotates at the same speed. The speed of rotation
depends directly to the supply frequency and inversely on the number of on stator magnetic poles.
They are generally used where low-speed and high horsepower drive is required.
2.4.2.3 INDUCTION MOTORS
In induction motors, AC power is fed to the stator and a magnetic field is set up and then induced
in the squirrel cage like rotor windings. Induction motors are supplied by one AC power source.
These are the cheapest and simplest type of electric motors and are the workhorse of industry.
2.4.3 PNEUMATIC/HYDRAULIC CYLINDER
These cylindrical actuators make use of fluids to move linearly or rotational movement in relation
to amount of fluid supplied. In pneumatics, cylinders are the most common means of actuation.
Normally these devices are controlled by solenoid valves which can be connected to a controller
and a fluid source. Fluid will be supplied to the cylinder via the solenoid valve and is released
again via the solenoid valve. Some major parts of pneumatic cylinders are shown on the diagram
fig 2.9 below.
22
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 2.9: Pneumatic cylinder
(Pneumatik, 2019)
2.4.4 PNEUMATIC ACTUATOR
Fig 2.10: Pneumatic actuator
(Mapol, 2013)
These are devices that are used for powering mechanical valves to open and close them remotely.
Mostly pneumatic actuators are used where instrument air/ compressed air at between four to six
bars of pressure in applied to open or close it.
23
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
The picture shown above, fig 2.10, is one of the most commonly used actuators the Dinactair
type actuator. For controlling the actuator remotely, a switch box for ON/OFF control or a
control positioner for a variable control has to be available and will be connected to a controller.
The main parts of a pneumatic actuator are:
The body- this is the outer casing of the instrument that holds other components inside it.
Springs- these are found on each side of the actuator.
Fig 2.11: Pneumatic actuator parts
(Supplyline, 2019)
Each side can hold a maximum of six springs as the figure 2.11 above depicts, but for easy opening
of the valve and to use less bars of instrument air five or four on each side are used. The springs
are located between piston guides and the cover. When instrument air is supplied between two
piston guides, opening a valve, they are pushed outwards compressing the springs. When the valve
needs to be closed it is the duty of the springs to push away the air inside by them returning to their
rest/initial position.
Piston guides- These are gears between the springs and the piston. They are attached to a piston
that moves anticlockwise for opening and clockwise for closing of the valve or vice versa when
the orientation is reversed. Piston guides will be coupled together with a piston in such a way that
the two components will produce the required direction of movement when instrument air is
supplied.
Piston- this is a shaft that has gears on its middle body where piston guides will be attached. It has
its ends protruding on two sides of the actuator (top and bottom). One side is where the valve will
be coupled (the bottom side) and the other end that’s where a positioner or switchbox will be
connected (the top side). For complete opening, the piston has to move 90 degrees anti clockwise.
24
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
This is when the valve being used either ball valve or butterfly will align itself in such a way that
maximum flow will be achieved
Instrument air ports- they are two of them, one for supply and one for pressure out when actuator
is closing the valve, clockwise direction, when springs are being pushed sideways by compressed
air inside the actuator.
Seals and O-rings- these are rubber and plastic lines which are placed on piston guides and spring
covers so as to reduce air leaks
2.5 CONTROLLERS USED FOR THE AUTOMATION PROCESS
2.5.1 PROGRAMMABLE LOGIC CONTROLLERS
These are a special type of digital computers that are meant for industrial use and other home or
office uses and are responsible for process automation. Traditionally devices will be connected
and linked together through relay logic systems according to how the system is intended to operate.
Now using PLCs, they act as a link between devices and the sequence of steps on how the system
operates are loaded or programmed to the PLC. The sequence of steps is technically known as a
control program, which can be written in many different languages. According to the international
standard for PLC languages, IEC 1131-3, there are about five PLC programming languages, which
are
Ladder Logic programming
Sequential Function Charts programming
Function Block Diagram
Structured Texting
Instruction List
A PLC uses its inputs from sensors to read process states and act upon it according to the control
program. This cyclic operation is illustrated by fig 2.12 below. It act using actuators that are
connected to the output modules and these will drive the system to new states that are again sensed
and transmitted to the PLC by sensors thus creating a cycle called a control loop of reading inputs
comparing inputs with the control program and change the outputs as shown below
25
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 2.12: PLC and field process link
(Automation, 2018)
A PLC has input modules where sensors and other input devices will be connected and output
modules where actuators will be connected and linked to the controller CPU. Other modules
including communication modules like Ethernet module, ControlNet and Device Net will be
connected to the CPU through a back plane. The diagram below shows a PLC with its power
supply unit on the extreme left, the CPU and its modules.
Fig 2.13: Allen Bradley PLC
(Bradley, 2017)
A PLC has about five components that are shown on the diagram below, fig 2.14, which are the
power supply, central processing unit(CPU), input modules, output modules and memory. A
programming device will be needed for writing the control program
26
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 2.14: PLC system
A PLC has many advantages, which include:
Flexibility: One single Programmable Logic Controller can easily run many machines as
long the input/output module still accommodate devices.
Correcting Errors: In old days, with wired relay-type panels, any program alterations
required time for rewiring of panels and devices. With PLC control any change in circuit
design or sequence is as simple as retyping the program. Correcting errors in PLC is
extremely short and cost effective.
Space Efficient: Today's Programmable Logic Control memory is getting bigger and
bigger this means that we can generate more and more contacts, coils, timers, sequencers,
counters and so on. We can have thousands of contact timers and counters in a single PLC.
Low Cost
Testing: A Programmable Logic Control program can be easily tested, evaluated and
corrected saving very valuable time.
Visual observation: When running a PLC program a visual operation can be seen on the
screen. Hence troubleshooting a circuit is really quick, easy and simple task.
Ruggedness: It is designed to withstand vibrations, temperature, humidity, and noise
though up to certain levels.
Easy language: PLCs are easily programmed and have easily understood programming
languages.
2.6 WORKING PRINCIPLES OF DIFFERENT CFHCS
2.6.1 MANUAL LEVELLING
27
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
This is the traditional, oldest and the most common method of sugar cane levelling in the main
cane carrier for sugar industries. Workers or front-end loaders as shown on the diagram below, fig
2.15, will load the cane carrier or in the crushing machine directly for small-scale industries. They
use their sense of sight or the behaviour of machines and mechanical components to see if the feed
rate is relating well with the machines.
Fig 2.15 manual levelling by front-end loaders
As shown on the diagram above the front-end loader will be loading the cane carrier as well as the
feeder table and the loader operator will be trying to maintain a constant level in the cane carrier,
which corresponds to the required crush rate
2.6.1.1 ADVANTAGES
Simplest method of sugarcane levelling
Cheap to maintain and construct
Easy control
2.6.1.2 DISADVANTAGES
Least accurate thus there is fluctuations in the level of the cane
Labour intensive
The system is prone to chocks and jams due to human errors
28
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
2.6.2 PROBLEMS ENCOUNTERD IN MANUAL LOADING
This simple and oldest method of sugarcane feeding is widely used by small-scale sugar
industries because of its simplicity and easy to set up and does not require much skill. It also has
its cons when matters of productivity, material lifespan, downtime, efficiency, and reliability
arise. The system does not match the semi-automated system in all the matters listed.
2.6.3 LEVELLING BY CONTROLLING FEEDER TABLE SPEED (SEMI AUTOMATED)
The system is the one that Green Fuel Ethanol Factory is currently using in controlling the level
of the feed. The major components of the system include a semi-automated, joystick operated
feeder table, a cane carrier and a cane-yard control room. Self-tipping trucks that transport sugar
cane from the fields in billet form will tip off the cane on the feeder table and the cane yard operator
will use a joystick with three slots each corresponding to a fixed speed of the chain drives on the
feeder table to load the cane carrier with the sugar cane. The diagram below shows a motor speed
control joystick.
Fig 2.16: Speed control joystick
The operator’s judgement using eyes will be used to maintain the level of the cane in the cane
carrier. When the crush rate present (process variable) is below the set crush rate (set point) the
cane yard operator will feed more cane in the main cane carrier by increasing the speed of the
feeder table thus moving a joystick to a higher notch. The opposite will be done when the
process variable is more than the set crush rate. Fig 2.17 below shows the orientation of the
elevated feeder table and a cane carrier.
29
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 2.17: Joystick controlled feeder table
2.6.3.1 ADVANTAGES
Less tiresome method as compared to the traditional way.
Simple method
Increased productivity through reduced steady state error through semi automation
2.6.3.2 DISADVANTAGES
A well trained cane yard operator/attended is needed for feeder table control
Jams and chocks are most common
2.6.4 PROBLEMS ENCOUNTERED IN SEMI AUTOMATED SYSTEMS
The system is far much better than the manual feeding of cane and exhibits more improvements as
compared to manual levelling. The system has its drawbacks also which include that a human
being is still responsible for feeding and levelling sugarcane in the cane carrier belt but this time
with a much smarter device, a joystick. Unevenness in the supply of cane to shredding and crushing
equipment is still the order of the day, which means feeder drum and its driving motor still face
the challenge of forced oscillations up and down yet they have to be stationary. Chocking in the
crushing equipment also is experienced when lumps of shredded cane, which have left feeder drum
strained, proceeding to the crushing rollers. This reduces productivity, as there is downtime in
trying to rectify the chock. In addition, there are no constant crush rates as the human operator is
prone to errors in maintaining a constant level of sugarcane to the shredding equipment.
30
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
2.7 RESEARCH GAP
Analysing the two existing methods of sugar cane feeding processes, there exists some issues of
concern which when addressed will increase life span of some equipment as well as increasing the
productivity and maintaining constant rates of crushing. One of the paramount reasons that lead to
these problems is the unevenness of the sugarcane that is supplied to the shredding and crushing
equipment. This has led to damage of the mechanical parts, reduced productivity, increased
downtime and variable crush rates. This script has addressed the issue of unevenness of cane
supply in reducing the stated list of problems
2.8 CONCLUSION
The described system layouts, components and operational principles are of modern day and
traditional ways of sugar cane crushing systems
31
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
CHAPTER 3: METHODOLOGY
3.1 INTRODUCTION
This chapter describes how the desired solution of the problems encountered will work. It also
give detail to other possible designs in trying to solve the same problem. In coming up with the
desired solution of the problems a few aspects, have to be included for the system to work. The
system will try to improve the productivity of the whole sugar cane crushing process through
reduced downtime and reduced errors. The system proposed will be safe to use and provide no
harm to the human beings. The system will be reliable to work with through reduced complexity
and simple wiring of the system components.
3.2 POSSIBLE SOLUTIONS
3.2.1 LEVELER ON THE FEEDER TABLE
This is levelling at stage one that is as soon as the sugar cane is delivered at the feeder table. The
setup of the feeder table is a slanted metallic table with chain drives rolling on its top taking cane
from the lower side to the upper side delivering it to the next in line conveyor with the help of a
motor. The leveller on the feeder table will be moving along the feeder table using the rack and
pinion set up on both its drive ends. Where the cane is delivered from the conveyor is the home
position of cane leveller so it moves from the upper side to the lower side maintaining same level
of the cane as well as spreading it to all corners of the feeder table. It levels cane is it moves to the
lower side of the feeder table.
3.2.1.1 ADVANTAGES
Few components are needed
Simple technology
Few interlocks
3.2.1.2 DISADVANTAGES
Requires more material
Does not guarantee levelled cane to the shredding and crushing equipment
Huge structure
Does not have a fail-safe state
32
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.2.2 FEED GOVERNOR ON THE CANE CARRIER
When sugarcane is delivered on the feeder table, the chains will be driven at a constant but
adjustable speed delivering sugar cane to the cane carrier. The feeder table has three slots speed
representing three different speeds. The cane carrier also will be running at a constant but
adjustable speed passing through the feeder drum and the shredder. Three meters from where the
cane is being delivered from the feeder table there will be a feed control panel (feed governor),
that is electro-pneumatic controlled controlling the amount of cane to the shredder. When the
conveyor belts will be set in motion in their sequence of starting, the cane yard remote controller
(PLC) will control the set crush rate by adjusting the speeds of the conveyor and adjusting the feed
governor. Cane will be tipped off on the feeder table when all the belts are running smoothly.
When the crush rate, process variable, is above the set point, the governor will try to minimize
amount if cane passing by energizing its cylinders downwards and some upwards blocking some
cane. The opposite will be done when the process variable is below the set point, the governor will
adjust its opening in a ramp up manner to allow more cane to pass through thus increasing the feed
rate. The controller through an internal PID (proportional integral and derivative) controller will
adjust the governor in a proportional manner to the set crush rate.
Two proximity sensors are also part of the system. One sensor, which is an infrared proximity act
as a height marker to detect the maximum level of cane to be contained in the cane carrier. The
other sensor, the lateral sensor, which is an ultrasonic proximity sensor positioned at the back end
of the cane carrier senses backsliding of cane and prevents it from falling. Both sensors will be
interlocked with the feeder table through a controller. As the height marker detects cane for five
seconds, the controller will reduce the speed of a feeder table to slot two speed. If after sixty
seconds and the height marker still sensing presence of cane the controller will tune the speed of
the feeder table to slot one speed. If after two minutes, the height marker still senses some cane
the controller will stop the feeder table. Ten seconds after the height marker senses nothing the
controller will start the feeder table starting with speed, one up until three in ten seconds intervals.
When the lateral sensor detects cane at a distance of one meter, the controller will set the speed of
the feeder table to a lower speed. If thirty seconds after engagement of lower speed the sensor still
detecting something in its range, the controller will engage again a lower speed until it stops the
feeder table in thirty seconds intervals.
3.2.2.1 ADVANTAGES
Small size
Highly reliable
Yields levelled cane
Prevents chocks
Increased productivity
33
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.2.2.2 DISADVANTAGES
Needs skilled attended
3.3 EVALUATION OF THE POSSIBLE SOLUTIONS
3.3.1 DECISION MATRIX
Table 3.1 below shows the selection criteria in which the possible solutions were compared.
Property
Weight
Solution 1
(CFHCS)
4
4
7
14
9
8
2
8
8
50
114 ###
Solution 2 (feeder table
leveller)
6
8
12
10
5
6
2
5
8
20
82
System complexity
10
System size
10
Design cost
15
System reliability
15
Proper levelling
10
Prevents chocks
10
Safety criticality
10
Fault tolerance
10
Controllability
10
Does it address stated problem
50
TOTAL
150
Table 3.1: Decision matrix table
From the decision table shown above, matching each solution to the required user requirements
the sugar cane feed height control system (CFHCS) addresses and solve the given problems
3.4 DEVELOPMENT OF CHOSEN SOLUTION
The system is intended to control the amount of billet cane that is going to be shredded and then
crushed. The electrical, mechanical and software elements as well as control elements are listed
below.
3.4.1 SYSTEM WORKFLOW
This diagram shows the major stages of the whole process and their links to the other in
chronological order.
34
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.1: Work flow of CFHCS
3.4.2 SYSTEM FLOWCHART
The stage-by-stage description of the process is shown by the flowchart below, fig 3.2. The
controller decision on certain parameter changes are also shown on the flowchart.
35
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.2: Flowchart of CFHCS
3.4.3 PROCESS DESCRIPTION
The system with the structure and drawings shown above has its working principle described
below:
When sugarcane is delivered on the feeder table (made of chain drives) the chains will be driven
at a constant but adjustable speed delivering sugar cane to the cane carrier. The feeder table has
three slot speed representing three different speeds. The cane carrier also will be running at a
constant but adjustable speed passing through the feeder drum and the shredder. Three meters from
where the cane is being delivered from the feeder table there will be a feed control panel, feed
governor that is electro-pneumatic controlled controlling the amount of cane to the shredder. The
cane yard remote controller will set the crush rate and then the belts will be set in their sequence
starting with the last in line, up until the first in line. Cane will be tipped off on the feeder table
when all the belts are running smoothly. When the crush rate, process variable, is above the set
point, the governor will try to minimize amount if cane passing by energizing its cylinders
downwards and some upwards blocking some cane. The opposite will be done when the process
variable is below the set point, the governor will adjust its opening in a ramp up manner to allow
more cane to pass through thus increasing the feed rate.
36
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
During the start-up process with the help of the controller on the sequence of conveyor belts, the
shredded cane conveyor belt motor will be started first followed by the cane carrier motor and then
lastly the feeder table motor. The sequence crushing motors will be started and the kicker drive
motor will be started first followed by the feeder drum motor and then lastly the shredder motor.
The sequence of crushing motors will start first and then followed by the sequence of belts. When
the two sequences are done cane will then be delivered on the feeder table. The feed governor will
be at rest, thirty centimetres above the surface of the cane carrier, when the start-up sequences are
being followed. The controller through an internal PID (proportional integral and derivative)
controller will adjust the governor in a proportional manner, ramp function in relation to the set
crush rate.
Two proximity sensors are also part of the system. One sensor, which is an infrared proximity act
as a height marker to detect the maximum level of cane to be contained in the cane carrier. The
other sensor, the lateral sensor, which is an ultrasonic proximity sensor positioned at the back end
of the cane carrier senses backsliding of cane and prevents it from falling. Both sensors will be
interlocked with the feeder table through a controller. As the height marker detects cane for five
seconds, the controller will reduce the speed of a feeder table to slot two speed. If after sixty
seconds, the height marker still sensing presence of cane the controller will tune the speed of the
feeder table to slot one speed. If after two minutes, the height marker still senses some cane the
controller will stop the feeder table. Five seconds after the height marker senses nothing the
controller will start the feeder table starting with speed, one up until three in ten seconds intervals.
When the lateral sensor detects cane for five seconds, the controller will set the speed of the feeder
table to a lower speed. When it detects cane for sixty seconds, the controller will reduce the speed
to a lower slot speed. If the sensor detects cane two minutes after engaging lower slot speed, the
controller will stop the feeder table until the proximity of backsliding cane detects nothing for five
seconds.
3.4.4 MECHATRONIC SYSTEM DESIGN METHODOLOGY (VDI 2206)
This is a practical guideline for the systematic development of products, which require
combination of mechanical components, electrical and information technology components. This
guideline is shown by the diagram below, fig3.3. This guideline and its rules will be used in this
script for the design of the cane feed height control system/ cane feed governor. The procedures
of the model are in six steps, which are:
Requirements –this includes a precise description of the development order
System design- this is a conceptual solution, which shows the main characteristics of the product
to be made (physical and logical characteristics)
Domain specific design- this is a detailed mathematical design necessary for ensuring better
performance of the system
37
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Modelling and model analysis- this is grouped into physical, mathematical and numerical
modelling. This allows investigation of the system properties with computer softwares.
System integration- this brings together individual domains to form an overall system. It can be
distributed, modular or spatial.
Assurance of properties- actual system properties have to coincide with the desired system
properties. (Abdelhameed, 2014)
Fig 3.3: VDI 2206 Mechatronic system design model
(Mihailo P. Lazarević, 2008)
Now following the six steps of the methodology model:
3.4.4.1 SYSTEM COMPONENTS/ REQUIREMENTS
3.4.4.1.1 PNEUMATIC CYLINDERS
These compressed air powered cylinders will be used for vertical movement of the governor board
when a signal from the controller to the pneumatic positioner or current to pneumatic converters
(I /P converters) is transmitted. The pneumatic cylinders will be four of them two attached on the
elevated bar and two attached to the grounded bar. They will be connected pneumatically to the
converters. A picture of these cylinders is shown on fig 3.4 below.
38
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
(Hafner-Pneumatik, 2019)
Fig 3.4: Pneumatic Cylinder
The specifications of the pneumatic cylinders to be used are found through calculations
incorporation the load they are to work on. Several types of pneumatic cylinder are being used in
the industry, which include cylinders with piston rods, rodless cylinders, swivel cylinders and
stopper cylinders. For the proposed system, cylinders with pistons are incorporated and these are
divided into three types, which are single acting cylinders and double acting cylinders. On double
acting cylinders, instrument air is supplied for every direction on action. They are used together
with 5/2 way valves for on/off control. Single acting cylinders has a single point of instrument air
application and the compressed air moves the piston in one direction compressing a spring. For
the other direction air supply is removed and the spring will move the piston to its initial position.
3.4.4.1.1.1 DOUBLE ACTING CYLINDERS
The table 3.2 below contracts on the pros and cons of one of the type of cylinders, the double
acting cylinders.
Advantages
Constant force (dependent on stroke)
Long stroke distances
Disadvantages
Compressed air is needed for every movement
In case of failure the cylinder has no fail safe
state
Force is applied in both directions
Table 3.2: Advantages and disadvantages of double acting cylinders
39
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.1.1.2 SINGLE ACTING CYLINDERS
Another type of pneumatic cylinders the single acting types has its advantages and disadvantages
shown on the table 3.3 below
Advantages
Disadvantages
Reduced air consumption
Long construction length
Easy actuation
No equal forces in the two directions of motion
Has a fail-safe state
Stroke dependent thus no constant force
Force is applied in one direction
Table 3.3: Advantages and disadvantages of single acting cylinders
Property
Weight
Double acting
Single acting
Enough force
10
10
10
Simplicity
10
6
8
Cost
10
8
6
Safety
10
8
8
Controllability
10
8
6
TOTAL
50
40
38
Table 3.4: Decision matrix of the cylinders
From the above comparisons, the double acting cylinders are going to be used mainly due to their
controllability and force applicability in both directions.
3.4.4.1.2 I/P CONVERTERS
These are electro-pneumatic analogue devices that are used for actuator control. Figure 3.5 below
shows a converter mounted on a pneumatic cylinder. They give output of air pressure equivalent
to its analogue input if between 4 to 20 mA. The converters also have a compressed air input of
around eight bars, which they regulate to give an output. The current signal will be from the
controller, PLC. The output signal of compressed air pressure will be equivalent to the device’s
working range between 0 and 100% thus for the cylinders when they are not powered, 0%,4ma
and when they are fully open, 100%, 20 mA with a graduation between the two given minimum
and maximum ranges.
40
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.5: Current to pneumatic converters
(Indiamart, 2015)
Different types of positioners are used currently in industries, which include: There are different
types of control valve positioners force-balance pneumatic positioners, motion-balance
pneumatic positioners, electro-pneumatic valve positioners and electronic positioners. The most
common type is the electro-pneumatic valve positioner
3.4.4.1.2.1 ELECTRO-PNEUMATIC VALVE POSITIONER
The table below shows the advantages and disadvantages of using electro-pneumatic positioner.
Advantages
Disadvantages
Easily operated
Does not allow for sudden changes because air is compressible
Very flexibility
Air needs to be cleaned
It is reliable
Simplicity of Design and Control
Safe to work with
Can be stored under room conditions
Clean operations
Safe operation in cases of overloads
Table 3.5: Advantages and disadvantages of electro-pneumatic valve positioner
41
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.1.2.2 FORCE-BALANCE PNEUMATIC POSITIONER
Table 3.6 shows the advantages and disadvantages of using force balance pneumatic positioner.
Advantages
Disadvantages
Offers rapid and precise positioning
Less friction on the gland
Allows stand-alone mounting
Offers no hysteresis
Table 3.6: Advantages and disadvantages of force-balance pneumatic positioner
In deciding which positioner type to use in the system to be developed, a decision matrix like the
one shown below, table 3.7, is used.
Property
Weight
Force balance
Electro-pneumatic
Flexibility
10
8
9
Simplicity
10
6
8
Precision
10
8
10
Reliability
10
7
8
Safety
10
6
8
Robustness
10
8
6
TOTAL
60
43
49 ###
###- chosen
Table 3.7: Decision matrix of positioners
3.5.4.1.3 COMPRESSOR
This motorized extraction fan collects air from the surrounding environment and then pressurize
it for industrial uses. Different sizes of compressors give different bars of compressed air and for
the intended purpose, an eight bar output compressor will be needed. Fig 3.6 below shows a
compressor and its storage tank.
42
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.6: Compressor unit
(compressor, n.d.)
Compressors are grouped according to different characteristics, which are lubrication, mobility,
powering mechanisms, pressure and flow options. Under each parameter are different types.
Mobility compressors exists in two major types, permanent mount and mobile compressors.
3.5.4.1.3.1 PERMANENT MOUNT COMPRESSORS
Advantages and disadvantages of permanent mount compressors are shown on the table 3.8
below.
Advantages
Disadvantages
Less expensive
Not mobile
Easy upgrading
More lengths of air lines are needed
Broader electrical power options
Powerful
Greater capacity
Table 3.8: Advantages and disadvantages of permanent mount compressors
3.5.4.1.3.2 MOBILE COMPRESSORS
Table 3.9 below shows some of the advantages and disadvantages of mobile compressors.
43
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Advantages
Portable
Versatile
Little to no air hose is needed
Disadvantages
More expensive
Difficult to upgrade
Mainly available as electrically powered
Less air capacity
Table 3.9: Advantages and disadvantages of mobile compressors
Under lubrication type, compressors are grouped under oiled or non-oiled compressors
3.5.4.1.3.3 OILED COMPRESSORS
Oiled compressors have the following advantages and disadvantages.
Advantages
Durable
No heating
Powerful
They last longer
Disadvantages
Oil has to be changes from time to time
Continuous checking of oil levels is needed
Extra care is needed in maintenance
They are heavy
Expensive
Table 3.10: Advantages and disadvantages of oiled compressors
3.5.4.1.3.4 NON-OILED COMPRESSORS
There are also benefits in using non-oiled compressors but some consequences are also available.
Table 3.11 shows its pros and cons.
Advantages
Disadvantages
Cheap
Less efficient that oiled
Light in weight
They always run hotter
Less maintenance needed as compared to oiled Less durable
Table 3.11: Advantages and disadvantages of non-oiled compressors
Under power options, two types of compressors exists which are gasoline powered and electric
powered compressors.
3.5.4.1.3.5 GASOLINE COMPRESSORS
Advantages
Can be used where electricity is unavailable
For high performance uses
Disadvantages
Keeping gas is risky
Noisy
Powerful machines are heavy
Extra care is needed to operate the machine
Service/ maintenance is needed time and again
Table 3.12: Advantages and disadvantages of gasoline compressors
It can be concluded after studying table 3.12 that using gasoline compressors is quite risky as it
has more disadvantages than advantages.
44
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.5.4.1.3.6 ELECTRIC COMPRESSORS
The table 3.13 below shows the advantages and disadvantages of using electric compressors.
Advantages
Disadvantages
Easy to use power source
Requires heavy duty wiring
Suits well for permanent mount
Portable units of this type are less powerful
Heavy duty applications
Powerful units are expensive
Portable units of this type are compact
Table 3.13: Advantages and disadvantages of electric compressors
3.4.4.1.4 DRIER AND COMPRESSED AIR STORAGE TANK
The compressed air due to surrounding environment can condense or become moist so an air drier
will be needed for moisture removal in the compressed air. A storage tank will be needed for
storing the compressed air for use even if the compressor is not running. Stainless steel is normally
used for the fabrication of these storage tanks. A combination of these two parts is shown on the
diagram below.
Fig 3.7: Compressed air service unit
(Ultrafilter, 2017)
The size of the storage tank, which the system is going to need, is found through the calculations
in the Domain Specific Design stage.
45
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.1.5 PRESSURE TRANSMITTER
It is an analogue device that will be connected to the controller will measure the pressure of the
instrument air and will be positioned at the highest point within the system structure to cater for
pressure drops due to altitude. It will be interlocked with the compressor motor through the
controller program for the pressure to be maintained at the desired eight bars. One of the types of
pressure transmitters, the differential type is shown on the fig 3.8 below.
Fig 3.8: Differential pressure transmitter
(Eastsensor, 2018)
Pressure sensors are grouped in three main modes, which are absolute, gauge, and differential
measurement modes.
3.4.4.1.5.1 ABSOLUTE PRESSURE SENSOR
The table below shows advantages and disadvantages of using absolute pressure sensor over
other types.
46
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Advantages
Disadvantages
Eliminate any chance of fouling
How much pressure the atmosphere is adding to the equation
is not predictable they are being measured separately.
No dust or moisture disturbances
Uses full vacuum
Fixed baseline
No need for constant attention
Table 3.14: Advantages and disadvantages of absolute pressure sensor
3.4.4.1.5.2 GAUGE PRESSURE SENSOR
The table below shows advantages and disadvantages of using gauge pressure sensor over other
types.
Advantages
Disadvantages
Most common
Air expansion and contraction alters the
measurements
Cheap
Less accurate
Table 3.15: Advantages and disadvantages of gauge pressure sensor
3.4.4.1.5.3 DIFFERENTIAL PRESSURE SENSOR
The table below shows advantages and disadvantages of using differential pressure sensor over
other types.
47
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Advantages
Disadvantages
Wide range of applications
Costly than the two
More accurate than the other two
Bidirectional pressure measurement
Easy interface and configuring
Table 3.16: Advantages and disadvantages of differential pressure sensor
3.4.4.1.5.4 DECISION ON PRESSURE TRANSMITTERS
In choosing a pressure-measuring device suitable for the project, the decision matrix shown on
the table 3.17 below was used.
Property
Weight
Absolute
Easy interfacing 10
7
Configurations
10
6
Accuracy
10
5
Cost
10
8
Robustness
10
8
TOTAL
50
34
Table 3.17: Decision matrix of the pressure transmitter
Gauge
6
5
6
7
8
32
Differential
9
9
8
6
8
40 ###
###- CHOSEN
3.4.4.1.6 CONTROLLER
This will be the brain of the system where the system control program will be loaded. Robust
industrial controller, the programmable logic controller, PLC will be used for the control task of
the system. A PLC with analogue and digital inputs and outputs modules and Device Net
communication module will be the best for controlling all the system components. One of the
manufactures of PLCs, Allen Bradley has its brand Control Logix rack mounted PLCs shown on
fig 3.9 below.
48
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.9: Programmable Logic Controller
(Bradley, 2017)
Programmable logic controllers, PLCs, despite different manufacturers, exists in three different
types, which depends on the number of components and flexibility of a PLC. The three types are
unitary, modular and rack mounted PLCs.
Unitary PLCs have all the features and components of a basic PLC but all compacted on one unit
and are usually mounted on the system they are supposed to control. The table 3.18 below shows
some of the advantages and disadvantages of using unitary type PLCs.
Advantages
Disadvantages
Portable
Cannot be expanded
Holds all the components on one unit
They are just basic
Small in size
Utilizes less space
Cheapest type
Table 3.18: Advantages and disadvantages of unitary PLCs
The second type which is the modular PLC which is a combination of separate parts of the PLC
that are assembled together to build a PLC system. Its pros and cons are shown on the table 3.19
below.
Advantages
Disadvantages
Modules (I/O) can be expanded
Expensive
If one part fails it will not affect other parts
Table 3.19: Advantages and disadvantages of modular PLCs
49
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
The third type of PLC is the rack mounted PLC. It looks like the modular in the sense that
increasing rack size means expansion of the PLC. All the modules on this type communicate via
the back plane. Some of its advantages and disadvantages are shown on the table 3.20 below.
Advantages
Can be easily expanded
More input and output modules
If one part fails it will not affect other parts
Disadvantages
Most expensive type
Table 3.20: Advantages and disadvantages of rack mounted PLCs
The table below shows a matrix in choosing which type of PLC to use.
Property
Weight
Modular
Unitary
Expandability
10
8
4
Cost
10
8
7
Reliability
10
8
6
robustness
10
7
6
interfacing
10
8
8
TOTAL
50
39
31
Table 3.21: Decision matrix of the PLCs
###- CHOSEN
Rack
10
6
9
9
10
44 ###
3.4.4.1.7 INFRARED PROXIMITY SENSOR
This digital device will be used as a height marker for the level of cane in the cane carrier that is
supposed to be governed to the feeder drum. It will prevent overloading of the cane carrier. When
it sense the maximum allowable height of the cane for five seconds it will send a signal to the
controller to slow down the speed of the feeder table to clear off the cane carrier and will increase
the speed of the feeder table ten and twenty seconds after the sensor detects nothing. Fig 3.10
below shows an infrared sensor with the transmitter and the receiver at aits yellow end.
50
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.10: Infrared proximity sensor
(Shopbd, 2016)
3.4.4.1.8 ULTRASONIC PROXIMITY SENSOR
This measures the proximity of backsliding cane to the end of the cane carrier. This will prevent
cane from falling out of the cane carrier. The sensor will be interlocked with the speed of the
supplying feeder table thus the speed of the feeder table will be reduced when the sensor detects
cane in the range less than one meter for five seconds. The diagram below shows an example of
the ultrasonic sensor.
Fig 3.11: Ultrasonic sensor
51
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
(Engineering360, 2019)
3.4.4.1.9 MILD STEAL BOARD
This will be the main body of the governor, which will be moved by four pneumatic cylinders
attached on the body arms. The body will be of dimensions 1.2m*1m*0.04m and prismatic
(rectangular) arms of dimensions 0.04m*0.04m*0.4m. The body will have a sharpened edge for
easy penetration.
3.4.4.1.10 SOLENOID VALVES
These will be used for the operation of actuated digital valves. A solenoid valve is an electropneumatic device that is powered by a digital electric signal like 24 VDC and 0VDC like the one
shown on fig 3.12 below. The 24V will energize the device whereas the 0V will de-energize it.
When energized it will allow airflow to the required digital pneumatic device. The solenoid valve
will be connected to the pneumatic devices like cylinders or actuators using pneumatic tubes or
steel airlines.
Fig 3.12: Solenoid Valve
(Trimantec, 2019)
3.4.4.1.10.1 DIRECT ACTING VALVES
The table below shows some advantages and disadvantage of using direct acting solenoid valves.
52
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Advantages
Disadvantages
Full power is only needed when opening the Used for low pressure applications
valve
are able to hold open position with low power
No need for differential pressure to open
Variety of types (3/2 way, 4/2 way, 5/2 way)
Fast operation
Table 3.22: Advantages and disadvantages of direct acting solenoid valves
3.4.4.1.10.2 PILOT OPERATED
The table below shows some advantages and disadvantage of using pilot operated solenoid
valves.
Advantages
Less power is needed for operation
Disadvantages
They have to maintain full power to remain in
open state
Uses energy of streaming fluid
Slower than direct acting
Same coil can operate a number of valves
Minimum working pressure between 0.1 and
1 bar is required
Table 3.23: Advantages and disadvantages of pilot operated solenoid valves
3.4.4.1.11 SWITCH BOXES
These devices are coupled on the top of a pneumatic actuator to allow remote control of the valve.
It has two switches one for the open position of the actuator and the other switch for the close
position. They are only used for on/off or digital devices like digital valves. They have a cap that
will show the status of the actuator like what is shown on the fig 3.13 below with a red colour for
open.
53
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.13: Switch box
(Mapol, 2013)
3.4.4.1.12 PNEUMATIC ACTUATORS
Pneumatic actuators are devices that work with pressurized air to open or close valves, digital
valves or control valves using a command digital signal from the controller through the solenoid
valve. Fig 3.14 below shows an actuator that can be used for powering valves.
Fig 3.14: Pneumatic Actuator
(Mapol, 2013)
54
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.1.13 VALVES
These are mechanical devices that are used for opening or closing pipes or tubes. They can be
manually operated or automated through the use of actuators coupled to the valve spindle. Several
types of valve exist that include ball valves, butterfly valves and gate valves. A butterfly valve is
shown on the fig 3.15 below.
Fig 3.15: Butterfly valve
(Sölken, 2008)
Different types of valves are being used industrially and these include ball valves, butterfly valves,
gate valves and so on. Some comparatives have been done in trying to find out the best valve type
to be used.
3.4.4.1.13.1 BALL VALVES
The table below shows some of the advantages and disadvantages of ball valves.
Advantages
Disadvantages
Excellent operating characteristics
Sticky
low pressure drop
Abrasion when the fluid sticks to the valve
Less force needed to control the valve
They offer flexibility in the form of multi-way design
Lighter as compared to gate and butterfly valves.
Minimum catch-ups during operation
Quick response
Little to no leaks during service.
They are safe even under high-pressure conditions.
Table 3.24: Advantages and disadvantages of ball valves
55
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.1.13.2 GATE VALVES
The table below shows some of the advantages and disadvantages of gate valves.
Advantages
Very good closing feature
They provide laminar flow
Minimum pressure drop
Disadvantages
Slow operation
Requires many components like gearboxes to fully close or open
Large space is needed for assembly and maintenance
High fluid flow
Leakages especially under high pressure and temperature conditions
Repairing is difficult
Table 3.25: Advantages and disadvantages of gate valves
3.4.4.1.13.3 BUTTERFLY
The table below shows some of the advantages and disadvantages of butterfly valves.
Advantages
Disadvantages
They are accurate
They do not offer tight shut offs
Little maintenance needed
Reliable
Can be installed without dislocating the pipes
Table 3.26: Advantages and disadvantages of butterfly valves
The following decision table was used in selecting the best valve type to be used in the
development of the system.
Property
Weight
Butterfly
Gate
Ball
Accuracy
10
8
6
9
Maintainability
10
8
7
8
Reliability
10
9
8
9
Quick response
10
7
6
9
Smooth operation 10
8
7
8
TOTAL
50
40
34
43 ###
Table 3.27: Decision matrix of valves
###- CHOSEN
3.4.4.1.14 RUBBER WHEELS
These mechanical devices allow smooth rotation of mechanical parts to reduce wear and tear. They
will be rolling in the inner sides of rails when the governor moves. A picture of these wheels that
can be used is shown on fig 3.16 below.
56
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.16: Rubber wheels and holder
(Everbilt, 2019)
3.4.4.1.15 SPECIFICATIONS OF SYSTEM COMPONENTS
System specifications are shown on the tables 3.28 and 3.29 below
Part
Pneumatic cylinder
Air storage tank
Governor body
Pneumatic actuator
Valves
Specifications
40mm bore,100mm stroke ,single acting, 3-7 bar air
supply,
0.717 m3 carbon steel
1,2m*1m*0,04m stainless steel
DIN ISO 5211, 90o rotation,300Nm torque, max 7
bars pressure
Half inch ball valve,90o shaft driving angle, max 7
bars
20mm diameter, rubber type
Rollers and
mounting stand
Table 3.28: Hardware elements specifications
57
Quantity
4
1
1
2
2
4
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Part
Specifications
Pneumatic positioner
4-20ma, -25-85degC,0-6 bars
Compressor
230V, 1 phase,2HP,to feed 60L
Drier
Sfcm 110,230V 1 phase, half inch connections
Pressure transmitter
4-20mADC, 0-8 bars, 24VDC
Controller
AB 1756, L6 firmware version
Infrared proximity sensor
24V , 20-130cm
Ultrasonic proximity sensor
24V ,10-120 cm
Solenoid valve
3-2 way with coil
Switch box
24VDC, inductive sensor type
Table 3.29: Electrical elements specifications
Quantity
4
1
1
1
1
1
1
2
2
3.4.4.1.16 SOFTWARE ELEMENTS
AutoCAD- This will be used for the mechanical drawing of the governor system as well as
dimensioning the parts
Microsoft Visio- this multi-use office package will be used for the drawing of the process
and instrument diagram of the system as well as the work flow of the whole process. It can
also be used for electrical and mechanical drawings but cannot simulate them
Lucid Chart- a general drawing/design software that will be used for designing the
electrical wiring of the governor control system
Micro Logix 500 light- this is an Allen Bradley ladder logic programming and simulation
software which can be used for drafting the ladder logic program of the system.
3.4.4.1.17 USER REQUIREMENTS
Requirements of the system as the designer wishes and after some considerations are shown on
the tables 3.30 and 3.31 below.
Symbol
R1
R2
R3
R4
R5
R6
R7
Requirement
The system should limit the amount of cane to the crushing machine in relation
to the set crush rate.
The system will work with sugar cane billet of length between 25-30 cm and
radius below 5 cm.
The system must yield a variable crush rate of between 50 ton/hr. to 300 ton/hr.
The systems parts (pneumatic cylinders, rubbers wheels, I/P converters) have to
be maintainable.
The system must have a fail-safe state of its rest position (when it allows crush
rate of 50 ton/hr.)
The system should leave a gap of 30 cm above the cane carrier surface
The system should be reliable , easy and cheap to maintain
58
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
R8
Low power consumption
R9
The system should be user friendly and pose no harm to humans during operation
R10
The system’s pneumatic air supply pressure should be between 3 and 7 bars.
Table 3.30: System user requirements
FUNCTIONAL REQUIREMENTS
Function
GEOMETRY
Governor body
Sliding rails
Pneumatic cylinders
Pneumatic air pipes
MATERIAL



Governor body
Air pipes
Cylinder casing
Requirement
 1000mmx1200mmx40mm
 Mild steel
 Tip end
 Mild steel
 Cement mounted
 2.5 cm sliding troughs
 40mm bore
 100mm stroke
 Single acting
 1/2 inch
 Galvanized
 Connecting pieces
 Cheap
 Durable
 Corrosion resistant
 High tensile strength
 Low design cost
 Low operating cost
 Low maintenance cost
SAFETY
 Safe to work with
 Safe linkage with other machines
Environmental safety
MAINTAINABILITY
 Easy to maintain
 Availability of spare parts
PRODUCTION
 Meet set crush rate
Minimal deviations of set point
Table 3.31: Functional requirements of the system
COST
3.4.4.2 SYSTEM DESIGN
3.4.4.2.1 SYSTEM BLOCK DIAGRAM
59
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.17: Block diagram connection of CFHCS
The above diagram shows how all the electrical and control devices are connected to the controller
(PLC). Analogue and digital devices are labelled A/D respectively and will be connected to the
analogue (input or output) module or the digital (input or output) module respectively.
3.4.4.2.2 SYSTEM PID DIAGRAM
The system’s process and instrument diagram (PID) shows how the pneumatic system components
as well as the general components that does the intended process are interlinked together.
Instrument airlines are also shown on the diagram running from the source (compressor) to the
consumers (actuators). The drawing is shown on the fig 3.18 below.
60
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.18: Process and Instrument Diagram of CFHCS
3.4.4.2.3 GOVERNOR SLIDING RAILS
The following pictures fig 3.19 and fig 3.20 are of the sliding rails where the governor body will
be sliding on
Fig 3.19: Governor sliding rails
61
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.20: one side of the governor sliding rails
3.4.4.2.5 CYLINDERS
The diagram below is of the cylinders that are going to power the governor.
Fig 3.21: Pneumatic cylinder
62
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.2.6 GOVERNOR BODY
The governor body in three dimension is shown on the fig 3.22 below.
Fig 3.22: Governor Body
3.4.4.3 DOMAIN SPECIFIC DESIGN
3.4.4.3.1 PNEUMATIC CYLINDER CALCULATIONS
Total mass of the governor
The body is made up of mild steel sheets of 10mm thickness. Two faces are each made up of 1m
by 1m sheets , thus their volume is given by 2*(1.2m*1m*0.01m) which gives 0.024m3
Other two faces are made up of 1m by 8 cm sheets thus their volume is given by
2*(1m*0.08m*0.01) which gives 1.6E-3 m3
The two surfaces, which makes the pointy design, are of total volume given by
𝑉 = 2 ∗ [1.2 × 0.01 × √0.22 + 0.022 ]
V= 4.82E-3 m3
Total volume becomes 0.03042m3
Using the formula 𝑚 = 𝑉𝜌 and assuming density of mild steel to be 7850 kg/m3
Mass becomes 238.797kg.
63
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
For the rubber wheels,𝜌 = 1522𝑘𝑔/𝑚3 diameter of 0.04m, and a thickness of 0.01m,
The volume will be 𝑉
Volume calculation
= 𝜋𝑟 2 ℎ
………………………………Equation 3.1
Which gives a volume of 5.027E-5 for the four wheels
The mass of the four wheels using the formula 𝑚 = 𝑉𝜌 becomes 0.0765kg
The total mass of the governor body (metallic body plus wheels) will be 238.874 kg, which is
approximately 240kg. The total weight will be 2343.349 N or 2354.4 when using 240kg
For the four cylinders to push and pull the mass, each must apply a force of 2354.4 N/4 which
gives 588.6 N approximately 600N each. For cylinder pistons a 5 percent of the force is
subtracted to cater for friction. The working pressure for the cylinders is six bars equivalent to
600 000Pa hence the radius of the piston is calculated by
𝐹 = 𝑃𝐴
………………………………Equation 3.2
Force-Pressure relationship
600
The area will be 600 000 = 𝜋𝑟 2 , r=17.841 mm to give a diameter of 35.682 mm, approximately 4
cm. For allowance, if a 4 cm diameter piston is used, 𝐹 = 𝜋𝑟 2 𝑃
𝐹 = (600 000 × 𝜋0.022 ) − 5%
𝐹 = 228𝜋𝑁, this corresponds to 228pi/9.81 =73 kg.
All the four cylinders can lift a maximum of 292 kg mass.
3.4.4.3.2COMPRESSED AIR STORAGE TANK SIZING
Storage tank size is calculated using the formula
𝐶𝑃𝑎𝑡 = 𝑉 (𝑃1 − 𝑃2)
….………Equation 3.3
Storage tank size
Where V= volume of the tank
t= time for tank to go from maximum pressure limit to minimum pressure limit\
C= free air needed
Pa=atmospheric pressure
P1= maximum tank pressure
P2= minimum tank pressure needed
64
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
The following assumptions were made:
C= 1000ft3/min, time = 10 seconds, P1= 7 bars (pressure needed plus 1 bar), P2=3 bars
(minimum working pressure of pneumatic cylinders)
Using the above formula
𝑉=
𝐶𝑃𝑎𝑡
………………………………Equation 3.4
𝑃1−𝑃2
Storage tank capacity
100
× 10 × 101352.972
𝑉 = 60
700000 − 300000
V=4.2230ft3=0.119m3=119L that is approximately 120 litres
3.4.4.4.4 CYLINDERS SUPPORTING FRAME
Figure 3.23-27 shows the supporting frame of the cylinders combined with the sliding rails with
their views described as well as the dimensions.
3.4.4.4.4.1 TOP VIEW
Fig 3.23: Top view of cylinder supporting frame
65
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.4.4.2 FRONT VIEW
Fig 3.24: Front view of cylinder supporting frame
3.4.4.4.4.3 3D VIEW
Fig 3.25: 3D view of the cylinder-supporting frame
66
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.4.4.4 X ray VIEW
Fig 3.26: X-ray view of the cylinder-supporting frame
3.4.4.4.4.5 DIMENSIONS
Fig 3.27: sliding rails and cylinder support dimensions
67
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.4.5 CYLINDERS
The two consecutive figures below shows the cylinders in two dimension and three dimensional
view respectively.
Fig 3.28: front view of the cylinder
Fig 3.29: 3D view of the cylinders
68
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.4.6 GOVERNOR BODY
Figures 3.30 -33 shows the governor body in the views described as well as its dimensions
3.4.4.4.6.1 TOP VIEW
Fig 3.30: Governor Top view
3.4.4.4.6.2 FRONT VIEW
Fig 3.31: Governor Front view
69
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.4.6.3 3D VIEW
Fig 3.32: Governor 3D view
3.4.4.4.6.4 DIMENSIONS
Fig 3.33: Governor dimensions
70
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.4.7 DETAILED DESIGN OF ELECTRICAL WIRING AND CONNECTIONS
This section illustrates how different electrical components of the system are linked together
through the controller as the figure 3.34 below shows.
All the digital output devices will be connected to a 24 VDC from the controller through relay
switches and fuses.
For analogue devices the 4-20Ma current will be from the controller again which will correspond
to the amount of process variable they are measuring or controlling.
Fig 3.34: block diagram of the PLC-instruments wiring
3.4.4.4 SYSTEM MODELLING AND MODELLING ANALYSIS
3.4.4.4.1 MECHANICAL
Modelling mechanically is the process of coming up with three-dimensional solid bodies from
two dimensional drawings or sketches.
The 3D drawings of the governor body, sliding and support rails as well as the pneumatic
cylinders have been included in the domain specific design stage. The stress analysis of the body
is included in the results section of the project.
71
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.4.2 ELECTRICAL
The block diagram of the PLC (ABB 1756 controllogix PLC) based circuitry is to be used was
drawn using LUCID CHART and is shown below, figure 3.35.
The type of modelling done for the electrical part is purely physical.
Fig 3.35: Model of the wiring diagram
3.4.4.4.3 CONTROL
3.4.4.4.3.1 MODELLING OBJECTIVES
72
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
It is desired that the system have:
a fast rise time of less than 0.5 seconds
minimal overshoot of less than 0.5 %
zero steady state error
3.4.4.4.3.2 PHYSICAL MODEL
The system has four pneumatic cylinders acting as dumpers as shown on the diagram fig 3.36
below.
Fig 3.36: System’s physical model
D1=d2=d3=d4=d
3.4.4.4.3.3 ASSUMPTIONS
Frictionless rolling surface between rubber wheels and sliding rails
The governor moves from rest to its upper limit(a distance of 1.2 m) in 5 seconds
3.4.4.4.3.4 MATHEMATICAL MODEL
The mathematical model describing the system is given by
………………………….Equation 3.5
∈ 𝐹 = 𝑚𝑎
Newton’s second law of motion
4𝑏𝑥 ′ + 𝑚𝑥 ″ = 𝐹
73
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Carrying Laplace transform on both sides gives:
𝑚𝑠 2 𝑋(𝑠) + 4𝑏𝑠𝑋(𝑠) = 𝐹(𝑠)
𝑋(𝑠)
𝐹(𝑠)
1
………………………….Equation 3.6
= 𝑚𝑠2 +4𝑏𝑠
Laplace transform
Calculating b for each cylinder from the equation
𝑑𝐿
………………………….Equation 3.7
𝐹 = 𝑏 𝑑𝑡
Force-damping relationship of dampers
Where F is the force applied by each cylinder
L is the distance to be travelled
T is the time taken
Using pre-calculated values and the time assumed, F= 490.5N ,T= 5 sec ,L=1.2 m, the value of b
is 81.75
The mass of the governor body is 200 kg and the total force needed is 1942.43N
The transfer function now becomes:
𝑋(𝑠)
𝐹(𝑠)
=
1
200𝑠2 +327𝑠
………………………….Equation 3.8
Transfer function
3.4.4.4.3.5 NUMERICAL MODEL
Using a PID controller with the general transfer function given as:
𝑇𝐹 = 𝐾𝑝 +
𝐾𝑖
𝑠
+ 𝐾𝑑𝑠 =
𝐾𝑑𝑠2 +𝐾𝑝𝑠+𝐾𝑖
………………………….Equation 3.9
𝑠
PID controller transfer function
And a unit gain feedback mechanism together with the system/plant transfer function, the
SIMULINK model of the system is given below in figures 3.37 and 3.38.
74
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.37: System control loop
UNIT FEEDBACK CLOSED LOOP CONTROL SYSTEM
e
CONTROLLER
(Kds2+Kps+Ki)/s
u
PLANT
1/(200s2+327s)
y
R= set point
E= error signal
U= control signal
Y= process variable
Fig 3.38: Closed loop control system with unit gain
A PID controller code using MATLAB of the system attached in the Appendix produced the
model transfer functions as given below
p=
1
---------------200 s^2 + 3270 s
Continuous-time transfer function.
75
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Kp =1.3435e+06
Ki =5.4101e+06
Kd = 8.2201e+04
C=
1
Kp + Ki * --- + Kd * s
s
with Kp = 1.34e+06, Ki = 5.41e+06, Kd = 8.22e+04
Continuous-time PID controller in parallel form.
T=
8.22e04 s^2 + 1.343e06 s + 5.41e06
--------------------------------------------200 s^3 + 8.547e04 s^2 + 1.343e06 s + 5.41e06
Continuous-time transfer function.
Using auto PID tuning which is a MATLAB toolbox, a MATLAB code and a Simulink model can
be made to come up with the required gains of the controller. To obtain the desired response of the
system and gains of the PID controller, the following steps were made.
Finding the open-loop response and determine which values to alter or add
Add a proportional controller which improves rise time
Add a derivative controller which reduces overshoot
Lastly add an integral controller which will reduce the steady-state error
Each gain is adjusted until desired overall response id obtained. The PID tuner, MATLAB
toolbox was used to determine optimum values of Kp, Ki and Kd. The requires parameters
to be achieved are fast rise time, minimal overshoot and zero steady-state error
3.4.4.5 SYSTEM INTEGRATION
This section brings together individual domains that are the mechanical, control and electrical to
form an overall system. It can be distributed, modular or spatial and in this case, the integration
will be distributed in the sense that the controller and its modules will be in a separate place that
is the MCC (Motor Control Centre), the mechanical structure, and some components like
pneumatic cylinders, valves and positioners will be in the field. The integral diagram is shown on
the figure 3.39 below.
76
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 3.39: System integration
3.4.4.6 ASSURANCE OF PROPERTIES
In this section, the actual system properties are compared with the desired system properties and
for a good system model, the properties have to coincide.
3.4.4.6.1 DESIRED SYSTEM PROPERTIES
The table below shows the parameters of the properties as the requirements stated
Property
Overshoot
Rise time
Steady state error
Controller mode (P, PD, PI or PID)
Response time
Table 3.32: Desired system properties
Result
Less than 0.5%
Less than 0.5 seconds
Zero
PID
Less than 2 seconds
77
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
3.4.4.6.2ACTUAL SYSTEM PROPERTIES
The table below shows the parameters of the properties from the simulation
Property
Result
Overshoot
0%
Rise time
0.00876 seconds
Steady state error
Zero
Controller mode (P, PD, PI or PID)
PID
Response time
0.06868 seconds
Table 3.33: Actual system properties
From the two tables above the actual modelled system meets all the properties of the desired
system from the simulations made.
3.5 CONCLUSION
The VDI 2206 Mechatronic methodology model used allowed an explorative research to be carried
out in parts (electrical, mechanical and control) and led to the results and analysis of the results.
The design carried out shows that the current sugarcane feeding process can be automated as well
as eliminating the major problem of unevenness and other resultant problems like chocking.
78
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
CHAPTER 4: RESULTS AND TESTING
4.1 PID CONTROLLER ALGORITHM AND RESULTS
Below is an algorithm that was used to come up with the required gains of the controller.
1. Set PID gains to zero (Kp, Ki, Kd)
2. Increase Kp until the system start to oscillate
If error occurs quickly
Use large gain
Else
Use smaller gain
3. Record the value of Kp as ultimate gain Ku
4. Measure the period of the oscillation waveform
Record it as Ultimate period, Tu
5. Adjust the constants according to the following computations
Kp=0.6Ku
Ki=0.5Tu
Kd=0.125Tu
Fig 4.1 shows the GUI of the PID tuner with two graphs. The dotted line is termed baseline, which
corresponds to the gains (Kp, Ki and Kd), which the user manually and iteratively came up with.
The solid line is the tuned responds with the help of the PID tuning toolbox.
79
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 4.1: PID tuning reference tracker of baseline graph and tuned graph
The variables and results describing the system’s response is in the table below.
80
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig4.2: Parameters and results of the baseline and tuned graphs
The tuner has optimized the system and came up with the response results above (column
labelled Tuned) but with an overshoot of 0.3%, which is under the accepted range of the
overshoot and its peak is exactly at 1, which is the equilibrium point.
The results corresponding to the gains (column labelled Baseline), which were iterated, are an
overshoot of 0% but the peak of the graph never reaches the equilibrium point 1. Its peak is
0.967
Hence taking the tuned results and inputting the gains into the PID program, the report below
was generated. Different controllers were used that are P, PI, PD and PID and their behaviours
are shown on the graph below.
p=
1
---------------200 s^2 + 3270 s
Continuous-time transfer function.
Kp =1.3435e+06
Ki = 5.4101e+06
81
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Kd =8.2201e+04
timer = 1
2
3
4
5
C=
1
Kp + Ki * --- + Kd * s
s
with Kp = 1.34e+06, Ki = 5.41e+06, Kd = 8.22e+04
Continuous-time PID controller in parallel form.
C1 =
1
Kp + Ki * --s
with Kp = 1.34e+06, Ki = 5.41e+06
Continuous-time PI controller in parallel form.
C2 = Kp + Kd * s
with Kp = 1.34e+06, Kd = 8.22e+04
Continuous-time PD controller in parallel form.
C3 = Kp = 1.34e+06
P-only controller.
x= 0
0.0050
0.0100 0.0150
0.0200
0.0250
T=
8.22e04 s^2 + 1.343e06 s + 5.41e06
---------------------------------------------
82
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
200 s^3 + 8.547e04 s^2 + 1.343e06 s + 5.41e06
Continuous-time transfer function.
T1 =
1.343e06 s + 5.41e06
----------------------------------------200 s^3 + 3270 s^2 + 1.343e06 s + 5.41e06
Continuous-time transfer function.
T2 =
8.22e04 s + 1.343e06
------------------------------200 s^2 + 8.547e04 s + 1.343e06
Continuous-time transfer function.
T3 =
1.343e06
--------------------------200 s^2 + 3270 s + 1.343e06
Continuous-time transfer function.
83
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 4.3: Step response of P,PD and PID controllers
The figure above shows the step response of the system when different controllers are used.
84
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
Fig 4.4: PID tuning results
The modelling objectives, which are:
a fast rise time of less than 0.5 seconds
minimal overshoot of less than 0.5 %
zero steady state error
Were all met according to the results. Fig 4.4 shows the controller gains as well as the tuned
response the system in bold.
85
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 CONCLUSION
The sugarcane feed height control system allows smooth and less human intervention in the
crushing of sugarcane in the ethanol and sugar industries. It has been discovered primarily that the
function of the sugarcane feed height control system is to provide an even feed of sugarcane to the
crushing machines. By implementing the feed control system there will be reduced downtime, less
human errors, reduced wear and tear on mechanical components to name a few. The scope of this
article was on the design of an electro-pneumatic powered feed control system that is controlled
remotely by a PLC and make it operate automatically.
As the aim of the research stated, the design of the sugarcane feed height control system is
achievable by implementing the governor principle. The set objectives, which were:
To develop a control algorithm that will control the governor height (between 30 cm and
1.2 m) having a response time of at most two seconds
To design an electro-pneumatic powered sugarcane feed governor that retrofits on the
existing cane carrier (1m width and 1.2 m height )
To design a self-operating cane feed height control system (CFHCS) that require no
human intervention during operation
To achieve the aim were met according to the results and the simulations done. The response time
of the system to step function yielded a satisfactory result of about 0.1 seconds when compared to
the desired properties of the system. The designed system according to the stated dimensions can
fit onto the existing system, which will reduce implementation time.
Implementing the sugarcane feed height control system will cost about a thousand dollars and it
will guarantee return of investment after reduced downtime during chocks, increased productivity
through maintaining set crush rates.
5.2 RECOMMENDATIONS
The sugarcane feed height control system can be modified by using stand-alone
pneumatic air source such that if the source of the whole plant is down that of the
governor will be running and will not stop the crushing process.
3D level scanners can also be incorporated and the pictorial view displayed on the
SCADA system for complete visibility of the evenness of the cane to be crushed.
Different controllers support different response times needed for specific systems. A
variety of controllers can be looked at to find those that can suit the required response
time.
The system can be improved so that it can be implemented alongside other methods so
that it can support parallel or series working with other systems.
86
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
CHAPTER 6: APPENDIX
6.1 MATLAB CODE FOR PID COTROLLER
clear all
clc
p=tf([1],[200 3270 0])%a transfer function of a 4 cylinder mass mechanism,
mass of 200kg, each cylinder 817,5 damping coeficient
Kp=1343467.5431
Ki=5410131.919
Kd=82201.3202
timer=[1 2 3 4 5]
C=pid(Kp,Ki,Kd)%using a PID controller
C1=pid(Kp,Ki)
C2=pid(Kp,0,Kd)
C3=pid(Kp)
x=0:0.005:0.025
T=feedback(C*p,1)% using PID CONTROLLER and a unit feedback
%the cane feed height control system must meet the following parameters
% fast rise time(<0.5seconds)
% minimal overshoot(<0.5%)
% zero steady state error
T1=feedback(C1*p,1)%using a PI controller
T2=feedback(C2*p,1)%using a PD controller
T3=feedback(C3*p,1)%using a P controller
step(T3,'y',T2,'b',T1,'g',T,'r')
axis([0 3 0 1.8])
ylabel('Amplitude')
title('Different controllers on CFHCS, Yellow-P,Blue-PD,Green-PI,Red-PID')
pidTuner(p,C)
87
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
6.2 LADDER LOGIC PROGRAM FOR THE PROCESS
88
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
89
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
90
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
CHAPTER 7: BIBLIOGRAPHY

Abdelhameed, P. D. M. M., 2014. VDI 2206. s.l.:s.n.

Asyiddin, N., 2007. Fluid flow measurement. [Online]
Available at:
http://www.piyushpanchal2007.mynetworksolutions.com/images/3._FLOW.pdf
[Accessed 5 September 2019].

Automation, E., 2018. PLC connections. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wjMtITi17jkAhUjA2MBHQ6DDhIQjhx6BAgBEAI&url=http%3A%2F%2Fmakox.com
%2Fplc-scada%2F1-introduction-of-plc-scada%2Fplcconnections%2F&psig=AOvVaw3YR7UbDyvq9UGav2aHliMw&ust=1567738646173
[Accessed 5 September 2019].

Bhatia, A., n.d. Principles and Methods of Temperature Measurement. p. 28.

Bradley, A., 2017. Allen Bradley controllogix. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wjm7tHLpbfkAhW8SBUIHZz1CN0Qjhx6BAgBEAI&url=https%3A%2F%2Fwww.pint
erest.com%2Fpin%2F486318459731865535%2F&psig=AOvVaw03yP2X2Bqgta8foQfp
BMNe&ust=1567690830228133
[Accessed 5 September 2019].

Bradley, A., 2017. Allen Bradley controllogix. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wjm7tHLpbfkAhW8SBUIHZz1CN0Qjhx6BAgBEAI&url=https%3A%2F%2Fwww.pint
erest.com%2Fpin%2F486318459731865535%2F&psig=AOvVaw03yP2X2Bqgta8foQfp
BMNe&ust=1567690830228133
[Accessed 4 September 2019].

Cancoppas, 2013. LEVEL MEASUREMENT for BULK SOLIDS & LIQUIDS. p. 2.

compressor, Q., n.d. Air compressors. [Online]
Available at: https://www.me.ua.edu/me416/s09/pdf/Air%20Compressors.pdf
[Accessed 4 September 2019].

Craig, K., n.d. Optical encoders, s.l.: s.n.

Dunlop, F., 2009. Conveyor handbook. June, pp. 20-36.
91
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM

Eastsensor, 2018. Smart differential pressure transmitter. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wieoNvlpLfkAhXZQRUIHV8KClcQjhx6BAgBEAI&url=https%3A%2F%2Fwww.easts
ensor.com%2Fproduct%2Fest4300-smart-differential-pressuretransmitter%2F&psig=AOvVaw2LOO36QiqnDHSA75a1SjkR&ust=156
[Accessed 4 September 2019].

Endress+Hauser, n.d. Level measurement. Product overview for applications in liquids
and bulk solids, pp. 12-13.

Engineering360, 2019. Ultrasonic sensor selection guide. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wjMqvP1rLfkAhU0olwKHQNgApIQjhx6BAgBEAI&url=https%3A%2F%2Fwww.glob
alspec.com%2Flearnmore%2Fsensors_transducers_detectors%2Fproximity_presence_se
nsing%2Fultrasonic_proximity_sensors&
[Accessed 4 September 2019].

Everbilt, 2019. Soft Rubber Swivel Plate Caster. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wirNWz1rnkAhUHKBoKHUh6BeAQjhx6BAgBEAI&url=https%3A%2F%2Fwww.homed
epot.com%2Fp%2FEverbilt-2-in-Soft-Rubber-Swivel-Plate-Caster-with-90-lb-LoadRating-49477%2F203661054&psig=AOvVaw2
[Accessed 5 September 2019].

Fritz Schmeißer, K. D., 1999. Rotational speed sensors KMI15/16. p. 8.

Hafner-Pneumatik, 2019. Chapter 7 - The pneumatic cylinder – part 1. [Online]
Available at: https://www.hafner-pneumatik.com/the_pneumatic_cylinder_part_1
[Accessed 4 September 2019].

Indiamart, 2015. Cylinder Positioner. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&ved=2ahUKEwju19PSm7fkAh
VDh1wKHVfPD7cQjhx6BAgBEAI&url=https%3A%2F%2Fwww.indiamart.com%2Fpr
oddetail%2Fcylinder-positioner9356026062.html&psig=AOvVaw29XsdpWjO870c9POLz3F-I&ust=1567688161757354
[Accessed 4 September 2019].

insights, M., 2019. Industry daily observer. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wiIjtad07jkAhUUAGMBHcA-
92
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM
DYwQjhx6BAgBEAI&url=https%3A%2F%2Findustrydailyobserver.com%2Fopticalencoders-market-rising-production-demand-and-supply-2019-to2025%2F112917%2F&psig=AOvVa
[Accessed 5 September 2019].

Kharagpur, n.d. Module 2 Measurement Systems. Temperature Measurement.

Mapol, 2013. Pneumatic actuators. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wjs7beZsLfkAhVPShUIHYPsACAQjhx6BAgBEAI&url=http%3A%2F%2Fwww.mapol
.org%2Fen%2Fpneumatic-actuators%2F&psig=AOvVaw1l_tO0V2_iaNyIxPNBaiO&ust=1567693677470930
[Accessed 4 September 2019].

Mapol, 2013. Pneumatic actuators. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wjs7beZsLfkAhVPShUIHYPsACAQjhx6BAgBEAI&url=http%3A%2F%2Fwww.mapol
.org%2Fen%2Fpneumatic-actuators%2F&psig=AOvVaw1l_tO0V2_iaNyIxPNBaiO&ust=1567693677470930
[Accessed 4 September 2019].

Mihailo P. Lazarević, V. S. V., 2008. Standard Industrial Guideline for Mechatronic
Product Design. 36(3), p. 3.

Pneumatik, H., 2019. The pneumatic cylinder. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wjmr9Dk1LjkAhV75eAKHXhQBPQQjhx6BAgBEAI&url=https%3A%2F%2Fwww.haf
nerpneumatik.com%2Fthe_pneumatic_cylinder_part_1&psig=AOvVaw1utUmacE2tPtpBIN
3ZQ8z1&ust=1567737860041906
[Accessed 5 September 2019].

Project, S. I. E. M., n.d. Electric motors. Module 6, p. 5.

Shopbd, 2016. Adjustable IR Infrared proximity sensor switch. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wjKs4j5q7fkAhXGNcAKHU1FAn4Qjhx6BAgBEAI&url=http%3A%2F%2Fwww.asho
pbd.com%2Fproduct%2Fe18-d80nk-adjustable-ir-infrared-proximity-sensor-switchashop-bangladesh%2F&psig=AOvVaw23Chhee_
[Accessed 4 september 2019].
93
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM

Sölken, W., 2008. Butterfly valves introduction. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wi59Pb_sbfkAhUOiVwKHcz4DIsQjhx6BAgBEAI&url=http%3A%2F%2Fwww.werma
c.org%2Fvalves%2Fvalves_butterfly.html&psig=AOvVaw0yQkiNLvvj0Qmh9tGmLVek
&ust=1567694160686074
[Accessed 4 September 2019].

Supplyline, G., 2019. Airtorque actuator supplier. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wjv8aak1rjkAhVh5OAKHX3sBW4Qjhx6BAgBEAI&url=http%3A%2F%2Fglobalsuppl
yline.com.au%2Fcatalogue-airtorqueactuators%2F&psig=AOvVaw1CejzOKKNfMHPlbXoAxAFC&ust=1567738260467783
[Accessed 5 Septeber 2019].

Takura, 2019. illustration of fluid flow parameters. [Art] (CUT).

Trimantec, 2019. Airtac solenoid air valves. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wikm6q2rrfkAhXNT8AKHTRuBCoQjhx6BAgBEAI&url=https%3A%2F%2Ftrimantec.
com%2Fcollections%2Fsolenoid-airvalves&psig=AOvVaw1FKRSAx1_aaqS7HPYlPjgv&ust=1567693201981476
[Accessed 4 September 2019].

Trimantec, 2019. Airtac Solenoid Air Valves. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wikm6q2rrfkAhXNT8AKHTRuBCoQjhx6BAgBEAI&url=https%3A%2F%2Ftrimantec.
com%2Fcollections%2Fsolenoid-airvalves&psig=AOvVaw1FKRSAx1_aaqS7HPYlPjgv&ust=1567693201981476
[Accessed 4 September 2019].

Ultrafilter, 2017. HRE Adsorption drier. [Online]
Available at:
https://www.google.com/url?sa=i&source=imgres&cd=&cad=rja&uact=8&ved=2ahUKE
wiNue_vo7fkAhWhVBUIHZknARoQjhx6BAgBEAI&url=https%3A%2F%2Fwww.ultr
a-filter.com%2Fcompressed-air%2Fadsorption-dryers%2Fhre-adsorptiondryer%2F&psig=AOvVaw2ohc8o07Cpa-Y0J8UmNEo1&ust=1
[Accessed 4 September 2019].

Sena Temel, Semih Yagli ,Semih Goren, EE402- Discrete Time Control Systems
Recitation 4 Report, PID controllers
94
TITLE: PLC BASED SUGARCANE FEED HEIGHT CONTROL SYSTEM


Maheswary mohan, Abhir Raj Metkar, Priyanka CP, 2016, A model reference adaptive
control system for the automatic control of cane feeding system in a cane sugar factory,
Volume 3
Technological studies, 2014, Pneumatic systems
95