A Capstone Experience-Development of a Flexible Manufacturing System (FMS)
using Smart Distributed Sensing System
S. Manian Ramkumar
Associate Professor
Manufacturing Engineering Technology Department
Rochester Institute of Technology
29 Lomb Memorial Drive
Rochester, NY 14623
Abstract This paper outlines a project involving the
development of an FMS in the Manufacturing Engineering
Technology Department at the Rochester Institute of
Technology. This project is currently in progress and is
expected to be completed by May 1998. The most
interesting aspect of this project is that it is being done as
part of an undergraduate capstone course called Process
Design and a graduate course on FMS.
The cell will be implemented using Smart Distributed
System (SDS1) from Honeywell Micro Switch. In this
system, the various sensors and actuators communicate
with the central control computer using field bus
technology. This is state-of-the-art technology in computer
based data acquisition and control.
The hardware and software aspects of the FMS are being
developed by a group of fifteen undergraduate students and
one graduate student, under the guidance of the author and
technical experts from Honeywell Micro Switch. The FMS
will consist of two identical milling centers and robots. The
parts will be transferred to the various stations on a pallet
using a conveyor system. An in-depth coverage of the
system architecture and control will be provided in the
paper.
Introduction
U.S. manufacturing continues to be challenged by stiff
overseas competition. The only way U.S. manufacturing
companies can succeed in a global marketplace is by
implementing newer manufacturing processes that enable
them to respond quickly to market changes and provide
high quality, low cost products. Automation is one major
step towards achieving the quality, cost and delivery targets.
In order to be successful with automation, the automation
systems need to be implemented properly and they should
be flexible and reliable. Many automation systems have
failed in the past due to poor implementation and lack of
understanding of the technology. Companies no longer
1
SDS is a trademark of Honeywell Inc.
enjoy the luxury of spending the time and money in training
somebody for a year or two before they become productive
entities within the workforce. Hence, it becomes imperative
to have a well trained workforce, right from start, that is
capable of implementing these systems and understanding
the technology and trends, thereby enabling companies to be
competitive. This manifests into the need for hands-on
training and education, within academic institutions, so as
to prepare future engineers who will be able to work in a
team environment. Recognizing this need, the
Manufacturing engineering Technology at the Rochester
Institute of Technology (RIT) has embarked on a mission to
provide well trained, well rounded, multi-skilled engineers
to the manufacturing workforce.
Manufacturing Engineering Technology
Department
The Manufacturing Engineering Technology Department is
ranked among the top 5 in the nation and has an enrollment
of about 250 full-time and part-time students.
The
department offers an ABET accredited undergraduate B.S.
degree program in Computer Integrated Manufacturing
(CIM) Engineering Technology and a M.S. degree program
in CIM. This curriculum’s emphasis is on providing
students with hands-on training in the various CIM
technologies. The courses in the program are currently
supported by four laboratories which include the Computer
Integrated Manufacturing, Machine Vision, CAD/CAM,
and Surface Mount Electronics Manufacturing. These labs
are used for lab exercises and student projects as part of the
various technical courses. The labs are constantly updated
and maintained current by generous donations from our
industry partners and grants from the Society of
Manufacturing Engineers (SME) and National Science
Foundation (NSF). The undergraduate students take courses
in the following areas:
• Traditional
&
Non-Traditional
Manufacturing
Processes
• CAD, CAM, & Computer Numerical Control (CNC)
• Controls for Manufacturing Automation & Computer
Based Data Acquisition Systems
•
•
•
•
Surface Mount Electronics Manufacturing
Basic Electrical Principles
Production & Operations Management
Engineering Economics
This broad based undergraduate curriculum with
emphasis on hands-on education and use of various
computer tools enable us in preparing well rounded
engineers for the multi-skill requirement of the
manufacturing environment.
The graduate program in CIM emphasizes software
development as a concentration. The graduate course
projects and thesis work are performed within the labs that
support the undergraduate program. This enables us to
perform advanced and focussed software development team
projects.
Undergraduate Capstone Course
The undergraduate curriculum includes a capstone course
called Process Design. This is a mandatory course offered in
the spring quarter of the graduation year and is completely
project oriented. There is very little lecture but a lot of team
meetings and discussions pertaining to the project. The
students are required to satisfy the following course
objectives:
• Design, develop and implement an automated
manufacturing system
• Work in a team environment for the completion of the
project
• Keep the product concept simple but focus on the
implementation of the process for the manufacture of
the product
• Understand the constraints and learn to work within a
given budget
• Provide two formal presentations
• Get a good understanding of the overall automation
concepts
The actual project spans over a period of twenty weeks.
The first ten weeks are spent planning the project and
designing the layout, fixtures, tooling, etc. The next seven
weeks are allocated for implementation, two weeks for
debugging and one week for final demo and presentation.
The planning phase of the project starts in the beginning of
the winter quarter of the graduation year.
Graduate Course in FMS
This course deals with the design and operation of FMS.
The graduate students are introduced to the various
hardware & software components, control architecture,
scheduling algorithms, etc. The emphasis is on software
development for FMS. The projects in this course include
the use of existing system integration software or the use of
C, C++ and visual basic programming.
Project Description & Objectives
The project for this year’s capstone course was to design,
develop, and build an FMS. The project team had the
following objectives to fulfill:
• The project should incorporate the use of SDS for
control
• The project should use two table top CNC milling
machines, three robots and a conveyor system
• The students are required to build necessary assembly
stations, fixtures, tools and end-of-arm-tooling
• Product concept should be simple and should be
something that can be distributed to visitors walking
through the lab
• The product should incorporate the flexibility required
to demonstrate an FMS
• The product should promote the manufacturing
engineering technology program
• The product should be manufactured using a material
that is easy to machine and should not require a
deburring operation
• The total expense is to be maintained within $3,500.
Project Team
The student team that was entrusted with this project
consisted of twelve manufacturing engineering technology
students, three mechanical engineering technology students
and one graduate student. Once the team was provided with
the project description and objectives, the first task was to
select a team leader and brainstorm various product
concepts that would meet the objectives. The team then
identified the product concept that will be economical and
also easy to build with the given set of equipment hardware.
The product chosen for this year’s project is a key chain
assembly shown below.
The details pertaining to the FMS hardware is provided in
the following sections.
Table Top CNC Milling Machines
Fig. 1 Key Chain Assembly
The team is then divided into groups consisting of four
or five students with a group leader. Each team becomes
responsible for one aspect of the cell from that point
onwards. The students are responsible for purchase of new
hardware, design and layout of the system, rectification of
existing problems, programming the equipment and
interfacing with the control system. The team leader
oversees the progress of the entire project while the group
leaders coordinate the activity within their team and interact
with other groups. The faculty does not get involved in
forming the groups. It is the responsibility of the team,
based upon the individual’s interest and expertise.
Two tabletop CNC milling machines are used for
machining the logos. These machines are controlled by
stand-alone computers that have specific software to run the
CNC programs. These programs use the standard N, G, F,
S, M and T codes. The machines also provide various key
features such as automatic clamp and unclamp of workpiece
and digital input/output (I/O) for interfacing with the
control system. These features are important when using
this machine in an automated environment. A SDS
fiberoptic diffused scanning photoelectric sensor mounted in
the work holding fixture senses the presence or absence of a
part in the machine.
Typical features found in machining centers, used in
any FMS installation, such as automatic tool changers
(ATC), automatic pallet changers (APC), tool wear
tracking, coolant on/off, etc, are not available in the table
top models. The schematic below summarizes the CNC
component of the FMS.
Sensor Signal to
SDS (Part present
or absent)
Table Top Milling
Machine
Product Flexibility
The three components that make the key chain assembly
include the key fob, the key ring and the clamp ring. The
flexibility required to justify the definition of an FMS is
introduced by milling different pre-defined logos on one
side of the key fob, based on user input. The other side of
the key fob is milled with a standard logo that promotes the
manufacturing engineering technology program.
The graphical user input option in the software
component of the FMS allows the user to select the logos
that need to be milled and the quantity for each logo. This
data is stored in a database that is periodically reviewed by
the main control software to initiate milling of the
appropriate logos.
The standard logo is pre-milled and hence both
machines are used for the other pre-defined user selected
logo. This introduces the concept of identical milling
centers capable of executing a variety of programs, typical
of any FMS.
FMS Hardware Components
Mill Controller
Digital Inputs
Digital Outputs
Computer
Fig. 2 CNC Milling Machine Schematic
Robots
Three articulated arm robots are used in the FMS. Two
robots are used for servicing the milling machines and one
is used for raw material load/unload and assembly. The
robots transfer the parts from and to the conveyor. Two
identical robots servicing two identical milling machines
makes this a two station FMS. The robots have memory
resident programs that do not change. The task to be
executed within the program is selected based on a signal
from the SDS that becomes the digital input signal for the
robot. The schematic below summarizes the robotic
component of the FMS.
The stand-alone automated assembly station receives
signals from the SDS system. The robot picks up the
finished part from the pallet, on the conveyor, and transfers
it to the assembly station. The key ring and the clamp ring
are automatically presented within the fixture in the proper
orientation. A pneumatic cylinder fitted with the clamping
gripper then clamps the ring by applying pressure for a
given period of time. The robot is then instructed to pick up
the assembly and deliver it to the finished product bin.
Robot
Smart Distributed System
Digital Inputs
Digital Outputs
Robot
Controller
Terminal
Fig. 3 Robot Schematic
Flex Link Conveyor System
The conveyor system used within the FMS is mainly to
transfer the raw material or finished goods from one station
to the other. Pneumatic stops on the conveyor at the various
stations stop the pallet as and when needed. The solenoids
for actuating the pneumatic stops are controlled by the SDS
system. Two SDS diffused scanning photoelectric sensors
are located at each station to detect the presence/absence of
raw material and finished part.
Assembly Station
CNC Mill
The smart distributed system, comprises a powerful devicelevel network, intelligent I/O devices, PC hardware and
software. SDS is based on a robust and open protocol called
the Control Area Network (CAN). The various I/O devices
used in SDS are embedded with CAN chips that provide the
intelligence required in a distributed environment. The
devices are identified on the bus using a unique address and
are capable of communications, diagnostics and decisionmaking. SDS provides the framework for true peer-to-peer
communication, thereby enabling devices to communicate
directly with other devices. This will result in increased
speed and efficiencies in control applications. The robots,
milling machines, and solenoid valves, which are not
designed to reside on the SDS network, communicate with
the SDS using intelligent quad I/O concentrators that can
interface up to four signals per connector.
Physical Layout of the FMS
The schematic below shows the layout of the FMS currently
being developed.
CNC Mill
I/O Concentrator
SDS
Robot
Robot
Trunk
Assembly
Station
Pallet Stops
Pneumatic Lines
Solenoid Bank
Conveyor
Termination
Robot
SDS Network Line
24 V DC Power Supply
To SDS Control
Computer
Fig. 4 FMS Layout
Control Architecture and Software
this package allows for interfacing to other PCs and other
networks.
The control architecture includes three personal computers,
one for SDS network and two for mill control. The
architecture currently being outlined for control of the FMS
is shown below.
Project Benefits
To Mill
Controller
To Mill
Controller
MILL1 PC
Slave
MILL2 PC
Slave
RS232 Serial Link
SDS PC
Host
SDS Network
The project enables RIT derive the following benefits
1. It helps the Manufacturing Engineering Technology
program provide excellent hands-on training, to
students, in the implementation of a complete
manufacturing systems
2. It enables RIT to provide well trained confident
manufacturing engineers to the workforce
3. It helps the students understand the various aspects of
automation, the difficulty involved and teamwork
required in developing systems like this
4. It enables the development of a fully functional model
FMS that will be useful for demonstrations to potential
donors and to potential students considering RIT’s
Manufacturing Engineering Technology program
5. It provides a customer demo facility for Honeywell
Micro Switch and possibly a beta testing site for their
new products
6. It helps faculty teach concepts in distributed sensing
and computer based data acquisition and control, for
future groups of students
7. It provides a framework for continuous improvement
Fig. 5 Control Architecture
The PC for the SDS acts as the host. The SDS network
originates from the PC, from an interface card plugged into
the computer’s bus, and terminates at the end of the
network. The various trunk lines required for connecting
the sensors and I/O concentrators will originate as a “T”
junction from the main network line. Each individual
sensor and I/O concentrator has to be programmed with its
unique address, type, model, etc. The SDS PC uses this
information for initializing the network. The SDS network
is powered by an external 24 V DC power supply.
The two mill control computers run special software
under DOS. They will be operating in a slave mode and as
and when the programs need to be changed for the logo, the
host PC will instruct the slave to run the appropriate
programs. This will be based on the number of key fobs
already completed for each logo and the user input.
The control software allows for real-time control of the
FMS. It includes a powerful windows based Human
Machine Interface (HMI) component and a control
application development component. The HMI provides
graphical user interface for logo selection and real-time
status report. The application control logic is implemented
as a flow chart. Multitasking and multithreading features
are also provided in the software. The network layer within
Conclusion
The project has been successfully completed in all respects.
All the course and project objectives were met. The students
were able to complete the development of the automated
cell, within the given time and budget and working as a
team. They were able to keep the product concept simple
and yet incorporate the flexibility needed, by selecting a key
chain assembly, after several brainstorming sessions and
ideas. This allowed the students to focus on the
implementation of the cell to manufacture the key chain
assembly. They provided two formal presentations one after
the first ten weeks of planning and one at the end of the
implementation phase. The students also had the
opportunity to tap into the knowledge and the experience
brought to the team by the graduate student involved.
The following is a summary of the student’s experiences, in
completing this project, based on student surveys and
evaluations.
1. Gained a thorough understanding of the teamwork
required in completing a project of this nature
2. Understood the importance of communication between
team members
3.
4.
5.
6.
7.
Understood the challenge in bringing together the
various technical skills and management aspects learnt
over a period of five years.
Learnt how to troubleshoot problems and work with
several constraints
Learnt the importance of proper planning and
organization in the successful completion of the project.
Learnt the importance of completing the various tasks
on schedule.
This was a great experience and it prepared us well for
accepting real life challenges in the industry.
Details pertaining to the CNC machine program, robot
program and the control logic program will be presented at
the conference. Overall, this effort has been a very
challenging and interesting experience.
Acknowledgements
The author would like to thank Prof. Guy Johnson, Chair,
Manufacturing & Mechanical Engineering Technology
Department for his support, the graduating class of 1998 for
their hard work and perseverance, Mr. Leo Dondis for
developing the control logic program and Honeywell Micro
Switch for their donation and support.
Bibliography
1.
2.
3.
4.
Honeywell Micro Switch SDS product literature
User manuals for the robots and CNC milling machines
William W. Luggen, “Flexible Manufacturing Cells &
Systems”, Prentice Hall.
Reza A. Maleki, “Flexible Manufacturing Systems-The
Technology & Management”, Prentice Hall