Appendix C
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Appendix
C
Student Projects:
Case Studies
In this appendix, several case studies with the student projects, where synthesis,
design, fabrication, and control of robotic arms and grippers are involved, are
presented. The robots discussed here are of two types, namely, those which were built
to take part in robotic contests, and those which were undertaken as a part of
undergraduate and postgraduate projects. The first set is strongly emphasised here, as
they involve all the stages of a product life cycle, and, hence, presented first.
C.1
ROBOTS FOR ROBOCON
ROBOCON, an abbreviation for ROBOtic CONtests, is a student robotic
competition organised by the Asian Broadcasting Union (ABU) every year. Even
though it was a popular robotic competition in Japan to their undergraduate students,
it was made open to other Asian countries in 2002. Since then an Indian competition
is organised by Doordarshan (Indian Television Broadcasting Company) to select a
representative team from India. Typically, the Indian champion represents the
country in the ABU-ROBOCON competitions held in different countries of Asia. So
far, Japan (2002), Thailand (2003), South Korea (2004), China (2005), Malaysia
(2006), and Vietnam (2007) have hosted the event. India will host 2008 ROBOCON
in Pune.
Under the guidance of the author teams from IIT Delhi have been participating the
Indian ROBOCON since 2003. In the following subsection, experiences from
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ROBOCON projects are presented. Reference to 2007 competition when IIT Delhi
became the Indian Champion is made as an illustration.
C.1.1 Experience of 2007
In the competition, two types of robots are allowed. One is ‘automatic’ type whose
job is to transfer blocks from the outer edges of the 10-sided polygon in the game
field, as shown in Fig. C.1, to the vertices of the triangles at the center.
Fig. C.1
Game field of 2007
These are preprogrammed robots. Hence, the term ‘automatic’ is used. The other
type is called ‘manual,’ which can be controlled using a joystick or switch-board by
an operator. The task of this robot is to transfer blocks from the corners of the square
field to the edges of the 10-sided polygon. Each successful transfer accrues points,
and the game proceeds. More than the exact rules, emphasis is laid in this book on the
design, fabrication and programming aspects.
Both the automatic and manual robots have a gripper to hold the blocks of about
300 mm diameter. It is important to synthesise an appropriate mechanism which
should be holding the blocks made of soft material without crushing it. At the same
time the blocks should not slip. The second aspect is the lifting and placing. Whereas
for the automatic robot shown in Fig. C.2, a pulley arrangement was used, for the
manual robot shown in Fig. C.3, a four-bar parallelogram mechanism was used. The
Appendix C
Fig. C.2
Automatic robot 2007
359
Fig. C.3 Manual robot 2007
latter can extend almost about half a meter in front of the robot to be able to place the
block inside the boundary line of the 10-sided polygon. Once the design is done, the
next level of challenge is to fabricate, assemble, program, and make them run
successfully.
From the experiences of the author, typically, the following aspects should be
looked into to successfully complete such projects:
1. Proper planning keeping in mind 5P’s (Proper Planning Prevents Poor Performance).
2. Maintaining a project diary by each student to record day-to-day activity,
sketches, information, etc.
3. Strictly follow a well-planned Gantt Chart. A typical Gantt Chart is shown in
Fig. C.4. In case the deadlines are not met, reasons are to be found out and
measures are to be taken without redefining the Gantt-Chart. In fact, the actual
schedule can be put below the planned one.
4. It is extremely important that the students learn how to work in a group. Particularly, the coordinators of different heads, e.g. Mechanical, Electrical, Fabrication, etc., should know how to distribute the work amongst other members
of his or her group. Otherwise, they may end up doing most of the jobs themselves, while others have no job. The latter group may get frustrated, and even
may leave the project.
5. Above all, dedication, sincerity, honesty, and positive thinking are must
amongst the members for successful participation, where the robots actually
move and perform their intended task, than just winning a game.
September
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Introduction to Robotics
Minor I, IISemester 1
Major
Minor ISemester 2
Formalisation
and Planning
Introduction
to First year
students
Study on
Rules
Team
Making
Market
Survey
Designing
Dr. Saha’s
Comments
Final Design
Mechanical
Fabrication
and Repair
Electrical
Fabrication
and Repair
Electrical
Installation
Game Field
Inspection
and Testing
Packaging
and
Transport
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TASK
Fig. C.4 Gantt Chart for Robocon 2007 participants of IIT Delhi
Appendix C
C.2
361
HANGING PLANAR ROBOTIC ARM (HaPRA)
As a part of mainly two B. Tech projects, the three-degree-of-freedom HaPRA was
developed. In the first project (Venugopal and Shabeer, 1996), an industrial task of
lifting cylindrical objects, e.g., piston heads, from one conveyor to a machine and
vice-versa was considered, as depicted in Fig. C.5. The configuration of the robot
arm, along with its dimensions, etc. were evaluated in this first project, which was
presented in a conference (Venugopal et al., 1997).
Front view
(slit)
(a) Cylindrical object (Piston head)
1
2
3
Sli
ttin
gM
K
In
Ex
it c
on
ve
c
or
ey
v
on
yo
r
(b) Transfer task
Fig. C.5 An industrial task by a robot arm
In the 2nd B.Tech project (Sharma and Ashutosh, 1997), fabrication of the same
was carried out. During the 2nd project, emphasis was given on low-cost aspect.
Since the payload was only about 500 gms, easily available chain-drives, namely,
bicycle chains, were chosen. The complete control was achieved using stepper
motors and a PC. The arm is shown in Fig. C.6. The detail design and development
work was presented in another conference (Baghla et al., 1999).
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Fig. C.6 Photograph of HaPRA and its controller
C.3
GRIPPER FOR CYLINDRICAL OBJECTS
This gripper is designed in another B.Tech project keeping in mind that the same can
be used for HaPRA explained in Section C.2 (Agarwal and Singh, 2004). For a range
of cylindrical shapes, the gripper is synthesised as a six-bar linkage, as shown in Fig.
C.7(a). Its complete kinematic analysis was performed using the motion option of
(a) Pro-E drawing
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363
(b) Control-interface
Fig. C.7 Gripper for cylindrical objects
Pro-E software. Finally, the gripper was fabricated and interfaced with a stepper
motor to demonstrate its motion capabilities, as shown in Fig. C.7(b). The project
was awarded in IIT Delhi as the Padamshri Manmohan Suri best hardware B.Tech
Project Award for the year 2004.
C.4
DIRECT-DRIVE ROBOT
This direct-drive robot, as shown in Fig. C.8, was developed in two M.Tech projects.
In the first one, the kinematic and dynamic analyses were performed and the arm
containing two-degrees-of-freedom was fabricated (Barma, 2001). Later, a third axis
was added in another M.Tech project (Ramvath, 2004), which should be useful for
real application of the robot in pick-n-place operations. The detail design
methodology was presented in a national conference (Ramvath et al., 2005).
(a) Photograph
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(b) Third axis (Prof-E drawing)
Fig. C.8 Direct-drive robot arm
SUMMARY
In this appendix, several robotic systems developed during the student projects are
presented. This will make the reader understand about the hardware and software
requirements to build a robotic system on their own.