Development of Reverse Vending Machine using Recycled Materials
and Arduino Microcontroller
Kai Kit Wong, Nur Atikhah Abu Samah, Mohamad Safwan Sahimi, W. A. F. W. Othman*
School of Electrical & Electronic Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Pulau Pinang,
Malaysia
* Corresponding E-mail: wafw@othman@usm.my
Abstract— This work is based on the theme of 3Rs which refers to three terms often used when referring
to waste, which is promoting Reduce, Reuse and Recycle. With the increasing amount of waste generated
and limited landfill space for waste disposal, recycling is now become one of the important approaches to
manage the waste effectively. The current manual recycling practice in which the user needs to bring the
waste in bulk to the recycling center might be a hassle and hence become a discouraging factor for them to
recycle. To overcome such an issue, Reverse Vending Machine (RVM) is designed specifically for the
recycling concept with a reward feature. The design is expected to aid in accelerating the motivation
among Malaysians to recycle their waste and can be one of the frameworks to overcome urban poverty
issue by using waste to wealth concept. Basically, the system is implemented with Arduino
microcontroller and several sensors. Once it detects the correct metal for recycling item, users will get an
instant reward. This is to motivate repeated use and further raising collection rates.
Keywords— Reverse vending machine; RVM; smart system; recycle; Arduino.
INTRODUCTION
The concept of automating the processing and
disposal of solid waste is not new. Currently, there
exist various types of machinery which attempt to
sort one material from another with differing
degrees of success. The key area of originality and
the emphasis of this work is to learn that readers
can make machine using recycled product that
contain CD / DVD old disc and certain recycle
item based on project’s theme.
I.
In this work, Arduino UNO, servo motors, LCD
display and capacitive sensor are used. The main
function of automatic sorting machine is to
separate different materials found in waste streams
and minimizing the amount of goods sent to
landfill. The weight of the waste material can be
displayed by LCD. For safety feature, alarm in
high pitch sound is fitted.
Arduino UNO is used in this project as the main
automatic machine to control the timer and sensor
so the time consuming to sort the machine will be
much effective and efficiently. CD / DVD old
discs are used in this design as the physical
structure of the machine. Furthermore, a short
introductory video of this work has been uploaded
to the YouTube; interested reader can find the
video
by
following
this
link:
http://y2u.be/oepPO6d2pHU.
PROBLEM STATEMENT
Modern world meets a lot of challenges that
includes smart waste management system. It is
becoming a matter of big concern if proper
disposal system is not well managed. A nation can
be said ahead of others if it can manage the waste
effectively and recycling efficiently. Metal is one
of the materials that have the highest percentage to
be recycled. However, most of the metal tin and
bottle use by consumer ended up in rubbish bin.
II.
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International Journal of Engineering Creativity and Innovation, 2019, 1 (1), 7-16
This is due to consumer awareness and willingness
to store metal tin or bottle waste before recycling
them.
0.36872 Million ton. Also, 2.7% of the recycle
material from household is metal recycle product
which is around 1 kiloton [3].
In this work, a reverse vending machine is
proposed and developed which can reward the
user after the user recycled metal tin or bottle into
the machine. The system can encourage more
consumers to recycle the metal waste product from
a small amount. By using the proper recycling
system, the curse of waste will turn into blessings
for the civilization. The sorting procedure will
make recycling more efficient.
IV. ESSENTIAL COMPONENTS DESCRIPTIONS
With so much concern recently about being
greener and economically friendly, waste
management has become a very important topic.
Communities and industries are starting to realize
that the materials they use and the way they
dispose of them can make a big impact to the
world. Proper management of waste plays a vital
role in global environment. That is why a reverse
vending machine is needed which can be used in
houses, offices; industries as a part of smart waste
management system and change consumer recycle
behavior into a habit.
In this work, there are several essential
components used to build the whole system. The
components include Arduino Uno development
board, inductive sensor, servo motors and LCD.
Arduino Uno
Fig. 1 shows an Arduino Uno development
board. Arduino is an open-source electronics
platform based on easy-to-use hardware and
software. Arduino boards able to read inputs light on a sensor, a finger on a button, or a Twitter
message - and turn it into an output - activating a
motor, turning on an LED, publishing something
online [4].
A.
With Arduino, users can tell the board what to
do by sending a set of instructions to the
microcontroller on the board. To do so you use the
Arduino programming language (based on Wiring),
and the Arduino Software (IDE), based on
Processing.
III. RELATED WORKS
In 2010, PepsiCo and Waste Management
launched a new Dream Machine initiative [1]. The
initiative was to test whether the Dream Machine
can work as a productive long-term bottle
recycling system for Americans. Furthermore, it is
also to test whether or not it motivates the
consumers to recycle. According to PepsiCo, the
recycling rate in America for 2010 was 34% [1].
However, the study done by NAPCOR in 2017
stated that, the recycling rate for America in 2017
was only 29.2% [2].
In Malaysia, only 17.5% of 13.752 Million ton
of waste produce have been recycled which equal
to 2.4066 million-ton Malaysia government expect
16.76 million of waste produce been generated in
2020 with the growth of 4% per year. Malaysia
government aim to increase the percentage of
waste produce recycle can increase to 22% which
is 3.6872 million ton. Base on Solid Waste and
Public Cleansing Management Corporation
SWCORP report, there will be 1 percentage of
recycle material from household which equal to
Figure 1: Arduino Uno development board
Arduino board designs use a variety of
microprocessors and controllers. The boards are
equipped with sets of digital and analog
input/output (I/O) pins that may be interfaced to
various expansion boards (shields) and other
circuits. The boards feature serial communications
interfaces, including Universal Serial Bus (USB)
on some models, which are also used for loading
programs from personal computers.
The microcontrollers are typically programmed
using a dialect of features from the programming
languages C and C++. In addition to using
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traditional compiler tool chains, the Arduino
project provides an integrated development
environment (IDE) based on the Processing
language project.
Furthermore, Arduino microcontroller is the
favorite microcontroller for most designers,
hobbyist and researchers. This can be seen by
many projects utilizing Arduino microcontroller.
These works include the works where Arduino is
used for controlling climbing robot [5~12], firefighting robot [13], humanoid robot [14-15],
Arduino as the brain for follower robot [16~18], as
controller for CNC machine [19~23], as a
controller for smart farming system [24].
Inductive sensor
Fig. 2 indicates an NPN inductive proximity
sensor. Inductive proximity sensor belongs to the
category of non-contact electronic proximity
sensor. It is used for positioning and detection of
metal objects. The sensing range of an inductive
switch is dependent on the type of metal being
detected. Ferrous metals, such as iron and steel,
allow for a longer sensing range, while nonferrous
metals, such as aluminum and copper, may reduce
the sensing range by up to 60 percent. In this
project, this sensor is used to detect metal tin for
recycle purpose. [25]
B.
Figure 3: Servo motor
LCD
LCD is the acronym for Liquid Crystal Display
(Fig. 4). LCD is a thin and flat electronic visual
display that uses the light modulating properties of
liquid crystal (LC). Since LC does not emit light
directly. LCD, therefore, needs a light source and
is classified as "passive" display. LCD is utilized
in battery-powered electronic devices because it
consumes small amount of electric power. LCD is
found to replace LED due to the declining price of
LCD, the ability to display numbers, characters
and graphics with ease of programming. LCD is
crucial in the work as it is needed to make the
whole system more user-friendly with metal
decompose and reward system information.
D.
Figure 4: Pins layout for LCD (Liquid Crystal Display)
V.
METHODOLOGY
System Overview
The operating system of the project is depicting
in Fig. 5 with block diagram showing the
mechanism and flow of the process of this work.
The mechanical system representing the physical
prototype which have difference chambers to
sense the recycle material, to store recycle
material and reward system chamber. The NPN
inductive sensor is the only sensor that uses to
differentiate the material (metal or nonmetal).
Arduino Uno development board is the
microcontroller that connects the whole system
with software. Servo motors that open the valve
A.
Figure 2: NPN inductive proximity sensor
Servo motor
Servo motor as shows in Fig. 3 is a selfcontained electric device that rotates or pushes
parts of a machine with great precision. It is a
rotary actuator or linear actuator that allows for
precise control of angular or linear position,
velocity and acceleration. It consists of a suitable
motor coupled to a sensor for position feedback
[26].
C.
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and push the reward and LCD display are the
actuator of the whole system.
Figure 5: Block diagram of the proposed reverse
vending machine
Schematic of Circuit Design
Fig. 6 shows the schematic circuit connection
between Arduino (microcontroller) with inductive
sensor, servo motors, and resistors. Several
resistors are used to limit the current flowing from
and to the microcontroller to prevent the
microcontroller from burning. A 16 characters
with 2 lines is also connected to the
microcontroller to display current status operation
to the user.
B.
Flow Charts of Reverse Vending Machine
Fig. 7 shows the flowchart of the system’s
behavior. As depicts in Fig. 7, at the beginning the
LCD will display “put metal only” to tell user only
to insert metal recycle material. When a metal
C.
recycle material is detected by the inductive sensor,
the LCD will display “recycle press D”. Then,
user need to press D to trigger the servo-1 which
represents the valve that holds the recycle material
in the sensing region to open and let the recycle
material falls into the recycle region.
After the servo-1 move back to its original
position where the valve closes, the LCD will
display “Reward press R” and “recycle again”. If
R button is pressed, reward will be push out. If
another metal recycle material is inserted into the
sensing region then the system will loop back
from LCD display “press D for recycle”. After
reward is given, the system is ends.
Circuit Implementation on Breadboard
Fig. 8 shows the photo of circuit
implementation for reverse vending machine
prototype with labels depicting its functionality.
As can been seen in Fig. 8, the R and D buttons in
blue are clearly labeled. The buttons are pushbuttons of normally open tactile type buttons.
D.
The Arduino Uno Development Board Ports
and Pins Connections
Table 1 shows the pin connection of Arduino
Uno development board to other components used
in this work. Digital output pins (2 to 7) of
E.
Figure 6: Schematic circuit diagram of reverse vending machine
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International Journal of Engineering Creativity and Innovation, 2019, 1 (1), 7-16
Figure 7: Flow chart of the proposed Reverse Vending Machine (RVM)
Arduino board are connected to LCD to show
information to the user. Digital input pins (10 &
11) are connected to normally open switches,
acting as the input selection of user, either R or D.
VI. RESULTS
A.
Prototype of reverse vending machine
Fig. 9 shows the prototype of reverse vending
machine, built by using recycled material as a
proof of concept working condition. Figure 9(a)
depicts the front view; 9(b) shows the back view,
9(c) illustrates the side view; 9(d) portrays the
mechanism of rewarding system respectively.
Interested readers can follow the following link to
watch the video of reverse vending machine in
action: http://y2u.be/oepPO6d2pHU.
Figure 8: Circuit implementation for reverse vending machine
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International Journal of Engineering Creativity and Innovation, 2019, 1 (1), 7-16
TABLE 1: PINS CONNECTIONS OF ARDUINO UNO DEVELOPMENT BOARD
Input / Output
Output from Arduino Uno to LCD
Input from button to Arduino uno
Input from servo motor to Arduino uno
Input from inductive sensor to Arduino uno
Arduino Uno Pins
Digital Pin 2
Digital Pin 3
Digital Pin 4
Digital Pin 5
Digital Pin 6
Digital Pin 7
Digital Pin 10
Digital Pin 11
Digital Pin 12
Digital Pin 9
Digital Pin 13
Result from literatures
Base on SWCorp report, in year 2020, expected
1 kiloton of metal include aluminum will be
recycled from household in Malaysia [3].
B.
Connection
Connect to pin RS of LCD
Connect to pin RW of LCD
Connect to pin D7 of LCD
Connect to pin D6 of LCD
Connect to pin D5 of LCD
Connect to pin D4 of LCD
Connect to 1 node of always open switch.
Connect to 1 node of always open switch.
Connect to signal pin of servo motor
Connect to signal pin of servo motor
Connect to black wire of inductive sensor
To produce 1kg of aluminum, 13 KWh of
energy is needed. And to produce 1 kiloton of
aluminum, 13000 MWh of energy is needed.
If new aluminum can be produced from recycled
(a)
(b)
(c)
(d)
Figure 9: Reverse vending machine prototype, build from recycled material as proof of concept. (a) front
view; (b) back view; (c) side view; (d) mechanism of rewarding system
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International Journal of Engineering Creativity and Innovation, 2019, 1 (1), 7-16
material, it only requires 5% of energy to
reproduce compared to raw material. So, in year
2020, total of 1235 MWh of energy can be saved.
With the reference of reverse vending machine
in UK, more than 95% of aluminum can be
recycled back [27]. This recycled figure is much
higher compare to traditional recycle method
which total of 17.5% of total waste produce been
recycle.
Thus, 1235 MWh of energy can be saved as
more than 95% of metal waste can be recycled
from the household.
Limitation
The current system has some limitation in terms
of hardware and software.
C.
1) The inductive sensor can differentiate metal
and nonmetal, but it is unable to future
differentiate the type of the metal like stain steel,
iron, aluminum and so on. This is because all
metallic object can create the electromagnetic field
in close surroundings of the sensing surface.
Although the operating distance of the sensor
depends on the actuator's shape and size and is
strictly linked to the nature of the material (as in
Table 2), the operation distance of the sensor is
too short (will describe in the next limitation) and
the difference between Sn and 0.4Sn is very small
[28].
TABLE 2: SENSING DISTANCE BETWEEN INDUCTIVE
SENSOR WITH DIFFERENT METALLIC MATERIAL
Sensitivity when different metals are present. Sn = operating
distance.
Fe37 (Iron)
1 x Sn
Stainless steel
0.9 x Sn
Brass - Bronze
0.5 x Sn
Aluminum
0.4 x Sn
Copper
0.4 x Sn
2) The inductive sensor model that we use is
NBB8-18GM50-E0 NPN normally open inductive
sensor which manufacture by Pepperl + Fuchs.
The rated operating distance, Sn is 8mm. The
assured operating distance, Sa is 0 to 6.48mm.
Thus, if distance between the metal object and the
inductive sensor is further than 8mm, the sensor
won't able to sense the material.
3) The size of the recycle material must be small
that 8cm in any dimension. This is because the
area of sensing chamber is only 8cm × 8cm.
4) In a mechanism part perspective,
maximum number of coins that can be put in
reward system is ten coins. This is because
mechanism part to hold the coin is (10) and
thickness of Malaysia 50sen coin is 2.18mm.
the
the
the
the
5) In a software perspective, the maximum
number of coin that can be put in that reward
system is 2,147,483,647 coins. This is because the
integral is assigned for the counting system. The
number 2,147,483,647 is the the maximum
positive value for a 32-bit signed binary integer in
computing. It is equal to equal to 231 − 1.
Discussion
The prototype built can function based on our
objectives. The reverse vending machine
constructed is capable to detect the presence of
metal object (tin). Then, the metal will be recycled
and reward user with instruction. The instruction
to recycle metal tin and the reward system will
display on the LCD screen. The success of sensor
with outputs implies that the interfacing of
Arduino Uno development system to NPN
inductive sensor, servo motors and LCD are
accomplished.
D.
Besides that, for the connection of the NPN
inductive proximity sensor and Arduino is active
high. NPN inductive proximity sensor is an always
open proximity sensor. Which mean that it will
only close when sensor is triggered by metal.
When the switch is opened, there is no current
flow to the pin. So, the circuit don't have voltage
drop and the resistor is short circuit. As, signal
back to Arduino pin is same node with ground,
Arduino pin receive LOW. When the switch is
closed, the circuit is completed and there is current
flow. So, the circuit have voltage drop between the
resistor. As this movement, signal back to Arduino
pin is same node with 5V, Arduino pin receive
HIGH (Fig. 10).
Other than that, for the connection of button and
Arduino is active low. The button is a always open
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International Journal of Engineering Creativity and Innovation, 2019, 1 (1), 7-16
button. When the switch is opened, there is no
current flow to the pin. So, the circuit don't have
voltage drop and the resistor is short circuit. As,
signal back to Arduino pin is same node with 5V,
Arduino pin receive HIGH. When the switch is
closed, the circuit is completed and there is current
flow. So, the circuit have voltage drop between the
resistors. As this movement, signal back to
Arduino pin is same node with ground, Arduino
pin receive LOW (Fig. 11).
measure the weight of recycle product, but we
failed to build a proper mechanism in our
prototype to get a accurate value.
2) In this piece of work, we faced problems in
detecting different kind of recycle material.
Solution: We decided to detect metal recycle
product only. So, the system will only detect metal
with inductive proximity sensor. We tried to use
capacitive proximity sensor to detect plastic bottle
as well with the concept of detect the density of
plastic material. However, the density range of
plastic material is too wide, and it may detect
other material as well.
3) In this project, we faced problems in
designing the mechanism part of the prototype.
Figure 10: Active high circuit of inductive sensor
Solution: We analyzed the motion that we need.
Then, we checked the components that we had.
With the engineering knowledge that we have
(dynamics and mechanism), we are able to design
the mechanism system of the reverse vending
machine.
CONCLUSION
In a nutshell, the aim and objectives of our mini
project are accomplished. We successfully build a
reverse vending machine to encourage more
people to recycle metal tin. The prototype of
reverse vending machine is constructed
successfully and is working normally. A step-bystep approach in designing the microcontrollerbased system for metal detection and reward
system has been followed. The results obtained
from the number of metals detected and recycled
is reliable and accurate to give users reward fairly.
VII.
Figure 11: Active low circuit of normally open button.
Problem Analysis
Throughout the period of project, we have
encountered problems during completing the task.
The problems that we encountered are listed below:
1) In this work, we faced problem in
measuring the reward given when certain amount
of waste product recycled.
E.
Solution: We decided to use counting system to
count the number of metal bottle or tin that user
want to recycle and give out equivalent reward
from them. We tried to use weight sensor to
Throughout the project, the knowledge learnt
from the mechatronics system lectures are applied.
The troubleshooting skill is also enhanced.
Understanding about microcontroller (Arduino
Uno), sensors and actuators are very important as
well to make sure all components able to interface
with each other in a right and efficient way. Also,
knowledge about mechanical design also very
important in this project to ensure every
mechanical parts function smoothly.
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International Journal of Engineering Creativity and Innovation, 2019, 1 (1), 7-16
Finally, we hope that our system can motivate
more consumers to recycle their used metal tin and
bottle and make it as a habit.
ACKNOWLEDGMENT
All authors have disclosed no conflicts of
interest, and authors would like to thank the
Universiti Sains Malaysia for supported the work
by Research University Grant Scheme (Grant
number: 1001/PELECT/8014113).
[1]
[2]
[3]
[4]
[5]
[6]
[7]
REFERENCES
NAPCOR, 2018. Report on Postconsumer
PET Container Recycling Activity in 2017:
Available
at:
https://napcor.com/wpcontent/uploads/2018/11/NAPCOR_2017Rate
Report_FINAL.pdf.
[Accessed
on
28/April/2019].
WM, 2011. Waste Management: Available at:
http://www.wm.com/about/pressU
room/pr2010/20100628_Dream_Machine_rec
ycling_kiosks_rolling_out_a
cross_the_country.pdf.
Accessed
on
[28/April/2019].
SWCorp Malaysia, 2014. SWCorp Strategic
Plan (Pelan Strategik SWCorp) 2014-2020.
Retrieved
from
http://goo.gl/J52vMN
[Accessed on 21/April/2019].
b_e_n, "Sparkfun," [Online]. Available:
https://learn.sparkfun.com/tutorials/what--is-an--arduino. [Accessed on 21/April/2019].
Mustapa MA, Othman WAFW, Abu Bakar E
et al. (2018). "Development of Pole-Like Tree
Spiral Climbing Robot". In: Hassan M. (eds)
Intelligent Manufacturing & Mechatronics.
Lecture Notes in Mechanical Engineering.
Springer, Singapore, pp. 285-293.
Bisht, R. S., Pathak, P. M., & Panigrahi, S. K.
(2018, September). Development of Magnetic
Adhesion Based Wheel-Driven Climbing
Machine for Ferrous Surface Applications. In
ASME 2018 Dynamic Systems and Control
Conference
(pp.
V001T04A016V001T04A016). American Society of
Mechanical Engineers.
Lau, S. C., Othman, W. A. F. W., & Bakar, E.
A. (2013, November). Development of slidercrank based pole climbing robot. In 2013
IEEE International Conference on Control
System, Computing and Engineering (pp.
471-476). IEEE.
[8] Rajasekhar, T. M. K., & Sugadev, M. (2018).
Arduino Controlled Special Stair Climbing
Wheel- chair Bot. International Journal of
Pure and Applied Mathematics, 118(24).
[9] Koo, Y. C., Elmi, A. B., & Wajdi, W. A. F.
(2012). Piston mechanism based rope
climbing robot. Procedia Engineering, 41,
547-553.
[10] Faisal, R. H., & Chisty, N. A. (2018). Design
and Implementation of a Wall Climbing
Robot. International Journal of Computer
Applications, 179(13), 1-5.
[11] Faizal MIN, Othman WAFW, Syed Hassan
SSNA (2015). "Development of pole-like tree
climbing robot", In. Proc. 2015 IEEE
International Conference on Control System,
Computing and Engineering (ICCSCE), IEEE,
pp. 224-229.
[12] Sivakumar, B. G., & Sudhagar, K. (2018). An
independent situating &navigation system for
stair climbing robotic wheelchair. Mental,
5(5.8), 5-4.
[13] Singh, D., Das, S. K., Das, E., Agrawal, M.,
& Patel, V. (2018). Arduino And Sensors
Based Fire Fighting Robot. i-Manager's
Journal on Instrumentation & Control
Engineering, 6(2), 37.
[14] Vital, J. P., Ferreira, N. F., & Valente, A.
(2018, September). Educational Humanoid
Robot Using A Sensoring Fusion Through
Arduino. In Memorias de Congresos UTP (pp.
235-242).
[15] Basyal, L., Kaushal, S., & Singh, G. (2018).
Voice Recognition Robot with Real Time
Surveillance and Automation. International
Journal of Creative Research Thoughts, 6(1),
2320-2882.
[16] Ahmad MF, Alhady SSN, Kaharuddin S, et al
(2015). "Visual based sensor cart follower for
wheelchair by using microcontroller". In.
Proc. 2015 IEEE International Conference on
Control System, Computing and Engineering
(ICCSCE), IEEE, pp. 123-128.
[17] Saad, W. H. M., Karim, S. A. A., Azhar, N.,
Manap, Z., Soon, Y. Y., & Ibrahim, M. M.
(2018). Line Follower Mobile Robot for
Surveillance Camera Monitoring System.
Journal of Telecommunication, Electronic and
Computer Engineering (JTEC), 10(2-7), 1-5.
[18] Sani NA, Syed SSNA, Othman WAFW, et al.
(2012). "Cordless Cart Follower for
Available online: http://technical-journals.org/index.php/IJECI/
P a g e | 15
International Journal of Engineering Creativity and Innovation, 2019, 1 (1), 7-16
Wheelchair User", Trends in intelligent
robotics, automation, and manufacturing,
Springer, Berlin, Heidelberg, pp. 252-262.
[19] Hirani, A. (2019). Design of mini CNC using
arduino uno.
[20] Hirani, A. (2018). Design of cost effective
CNC using Arduino Uno.
[21] Ahmed, B. J. S. A. A. (2018). Design and
Analysis Mini CNC Plotter Machine.
[22] Khan, M., Ahmed, M. K., Ulay, N. A. A.,
Sarwar, M., & Islam, N. (2018). Custom CNC
milling machine (Doctoral dissertation,
BRAC University).
[23] Sathyakumar, N., Balaji, K. P., Ganapathi, R.,
& Pandian, S. R. (2018). A Build-Your-Own
Three Axis CNC PCB Milling Machine.
Materials Today: Proceedings, 5(11), 2440424413.
[24] Cheong, C. K., Iskandar, A. M. K., Azhar, A.
S., & Othman, W. A. F. W. (2018). Smart
Aquaponics
System:
Design
and
Implementation
using
Arduino
Microcontroller.
[25] SS Intelligence. "SICK sensor intelligent",
[Online].
Available:
https://www.sick.com/us/en/proximity-sensors/inductive--proximity-sensors/c/g190731. [14/April/2019].
[26] Eglowstein, H. (2012). "Introduction to servo
motors". Science Buddies, [Online].
[27] Cost of a Deposit Return Reverse Vending
Machine., December 2017, [online] Available:
http://www.zerowastescotland.org.uk/sites/def
ault/files/reverse%20v%20%20CFE%20response.pdf. [Last accessed
14/April/2019]
[28] Operating Principles for Inductive Proximity
Sensors, March 2017, [online] Available:
http://www.fargocontrols.com/sensorslinducti
ve_op.html. [Last accessed 18/April/2019].
Available online: http://technical-journals.org/index.php/IJECI/
P a g e | 16