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DEVELOPMENT OF A UNIVERSAL JAMMING GRIPPER
PROJECT REPORT
SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF
BACHELOR OF TECHNOLOGY(Mechanical Engineering)
SUBMITTED BY: GUIDED BY:
SAHIL DUGGAL (80101114080) Dr. SEHIJPAL SINGH KHANGURASOURABH BAKSHI (80101114085) Dr. PARAMJIT SINGH BILGADHEERAJ GUPTA (80101114015)KARAN GOYAL (80101114045)JEEWAN KANIKA (80101114043)
DEPARTMENT OF MECHANICAL ENGINEERING
GURU NANAK DEV ENGINEERING COLLEGE, LUDHIANAMAY, 2012
Page 1
DEVELOPMENT OF A UNIVERSAL JAMMING GRIPPER
PROJECT REPORT
SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF
BACHELOR OF TECHNOLOGY(Mechanical Engineering)
SUBMITTED BY: GUIDED BY:
SAHIL DUGGAL (80101114080) Dr. SEHIJPAL SINGH KHANGURASOURABH BAKSHI (80101114085) Dr. PARAMJIT SINGH BILGADHEERAJ GUPTA (80101114015)KARAN GOYAL (80101114045)JEEWAN KANIKA (80101114043)
DEPARTMENT OF MECHANICAL ENGINEERING
GURU NANAK DEV ENGINEERING COLLEGE, LUDHIANAMAY, 2012
Page 2
GURU NANAK DEV ENGINEERING COLLEGE, LUDHIANA
CERTIFICATE
We hereby certify that the work which is being presented in the project report entitled
“DEVELOPMENT OF A UNIVERSAL JAMMING GRIPPER” by “SAHIL DUGGAL,
SOURABH BAKSHI, DHEERAJ GUPTA, KARAN GOYAL, JEEWAN KANIKA” in partial
fulfillment of requirements for the award of degree of B.Tech. (Mechanical) submitted in the
Department of Mechanical Engineering at GURU NANAK DEV ENGINEERING COLLEGE,
LUDHIANA under PUNJAB TECHNICAL UNIVERSITY, KAPURTHALA is an authentic
record of my/our own work carried out during a period from Jan, 2012 to May, 2012 under the
guidance of DR. SEHIJPAL SINGH. The matter presented in this project report has not been
submitted by us in any other University / Institute for the award of any Degree or Diploma.
Signature of the Student/s
SAHIL DUGGAL (80101114080)
SOURABH BAKSHI (80101114085)
DHEERAJ GUPTA (80101114015)
KARAN GOYAL (80101114045)
JEEWAN KANIKA (80101114043)
This is to certify that the above statement made by the candidate/s is correct to the best of my/our
knowledge
Signature of the Project Guide
HEAD OF DEPARTMENT
MECHANICAL ENGINEERING
Page 3
ABSTRACT
This project describes a simple passive universal gripper, consisting of a mass of granular material
encased in an elastic membrane. Using a combination of positive and negative pressure, the gripper
can rapidly grip and release a wide range of objects that are typically challenging for universal
grippers, such as flat objects, soft objects, or objects with complex geometries. The gripper
passively conforms to the shape of a target object, then vacuum hardens to grip it rigidly, later
utilizing positive pressure to reverse this transition—releasing the object and returning to a
deformable state. It describes the mechanical design and implementation of this gripper and
quantifies its performance in real-world testing situations. In addition, multiple objects are gripped
and placed at once while maintaining their relative distance and orientation.
Tasks that appear simple to humans, such as picking up objects of varying shapes, can be vexingly
complicated for robots. Secure gripping not only requires contacting an object, but also preventing
potential slip while the object is moved. Slip can be prevented either by friction from contact
pressure or by exploiting geometric constraints, for example by placing fingers around protrusions
or into the opening provided by the handle of a cup. For reliable robotic gripping, the standard
design approach is based on a hand with two or more fingers, and typically involves a combination
of visual feedback and force sensing at the fingertips. A large number of optimization schemes for
finger placement as well as the use of compliant materials for adaptive grasping have been
discussed. Given the evolutionary success of the multifingered hand in animals, this approach
clearly has many advantages. However, it requires a central processor or brain for a multitude of
decisions, many of which have to be made before the hand even touches the object, for example
about how wide to spread the fingers apart. Therefore, a multifingered gripper not only is a
complex system to build and control, but when confronted with unfamiliar objects it may require
learning the shape and stiffness of the object.
The focus of this work is on the problem of gripping, not manipulation, and seeks to offload
system complexities such as tactile sensing and computer vision onto unique mechanical design.
This approach replaces individual fingers by a material or interface that upon contact molds itself
around the object. Such a gripper is universal in the sense that it conforms to arbitrary shapes and
is passive in that all shape adaptation is performed autonomously by the contacting material and
without sensory feedback. This passive process reduces the number of elements to be controlled
Page 4
and therefore can have advantages in terms of reliability, cost, and gripping speed. So far,
however, passive universal grippers have remained largely unexplored. These bags conform to the
shape of any object they press against and, by simply evacuating the gas inside, can be turned into
rigid molds for lifting the object. However, the mechanism for this transformation was not
understood and no data about gripping performance were presented. As a result, these early
approaches to passive universal grippers never gained traction.
This project focuses on the simplest form of a gripper, a single nonporous elastic bag filled with
granular matter. This system approximates the limit of a robotic hand with infinitely many degrees
of freedom, which are actuated passively by contact with the surface of the object to be gripped
and are locked in place by a single active element, a pump that evacuates the bag. A wide range of
different types of objects are easily handled in pick-and-place operations using a fixed-base robotic
arm, without the need to reconfigure the gripper or even position it precisely, as long as it can
cover a fraction of a target object’s surface. This adaptability includes switching between objects
of different shapes, items difficult to pick up with conventional universal grippers, or fragile
targets like raw eggs, as well as simple manipulation tasks, such as pouring water from a glass or
drawing with a pen . The same type of gripper can also pick up multiple objects simultaneously
and deposit them without changing their relative position or orientation. For all of the items
depicted, holding forces can be achieved that exceed significantly the weight of objects of that
size. Its strength is due to three mechanisms, all controlled by jamming, that can contribute to the
gripping process: geometric constraints from interlocking between gripper and object surfaces,
static friction from normal stresses at contact, and an additional suction effect, if the gripper
membrane can seal off a portion of the object’s surface.
The handling of abstract materials and mechanisms to pick and place are widely found in factory
automation and industrial manufacturing. There are different mechanical grippers which are based
on different motor technologies have been designed and employed in numerous applications. The
designed robotic gripper in this paper is universal jamming gripper which is different from the
conventional cam and follower gripper in the way that controlled movement of the gripper is done
with the help of vacuum pumps which creates suction pressure. The force developed in the
cylinder is very gentle and is directly delivered to the gripper in a compact way. The design,
analysis and fabrication of the gripper model are explained in details along with the detailed list of
all existing pneumatic grippers in market. The working of the model is checked for and
observation for pay load is recorded at various pressures.
Page 5
The highly dynamic and highly accelerated gripper model can be easily set at intermediate
positions by regulating the pressure. Universal jamming grippers are very easy to handle and are
generally cost-effective because vacuum pumps, valves and other pneumatic devices are easy to
maintain.
Jamming in its most general form is controlled by three key parameters: the degree of geometrical
confinement (given by the particle packing density), the temperature, and the applied stress. For
this work, the focus will be on jamming occurring due to a pressure differential which we will call
vacuum jamming.
Vacuum jamming is commonly experienced in products such as vacuum packed coffee which is
shipped in a stiff (solid-like) brick. When this brick is punctured, releasing the confining vacuum,
the coffee particles behave liquid-like. Though jamming itself can do no net external work on the
environment to enable mobility, it can be used to modulate the work performed by another
actuator. For instance, consider the simple case of a ball made up of a jam able material with a
balloon in its interior. When the interior balloon is inflated and the jamming medium is in its liquid
state, the balloon can do work through the ball to the environment.
However, when the jamming medium is in a solid state, the balloon does not work on the
environment as long as the jamming medium does not yield. This example is in essence the mode
in which the first robot designed herein operates.
Virtually all particulate (granular) material exhibits the phenomenon of vacuum jamming.
However, the strength of the effect can vary based on the size, shape, and compressibility of the
particles.
In this project the main objective is to explore the possibility of picking up of various objects
having different geometry and shapes, effectively and efficiently.
Page 6
ACKNOWLEDGEMENT
The authors are highly grateful to the Director, Guru Nanak Dev Engineering College (GNDEC),
Ludhiana, for providing this opportunity to carry out the present project work
The constant guidance and encouragement received from Dr. Sehjpal Singh, Professor. and Head,
Department of Mechanical Engineering, GNDEC Ludhiana has been of great help in carrying out
the present work and is acknowledged with reverential thanks.
The authors would like to express a deep sense of gratitude and thanks profusely to Dr. Paramjit
Singh Bilga, Associate Professor, Er. Davinder Singh Bhogal, Asstt. Professor, Department of
Mechanical, GNDEC, who was our project guides. Without the wise counsel and able guidance, it
would have been impossible to complete the in this manner.
The help rendered by Mr Kamaljit Singh, Technician, Mr. Balbir, Mechanic, Mr. Kulwant Singh,
Attendant, Mr. Bahadur Singh, Attendant, Heat Engines Laboratory, Department of Mechanical
Engineering, GNDEC, for experimentation is greatly acknowledged.
The author express gratitude to other faculty members of Mechanical Engineering Department,
GNDEC and Head and Staff of Workshops, GNDEC for their intellectual support throughout the
course of this work.
Finally, the authors are indebted to all whosoever have contributed in this project work.
SAHIL DUGGAL (80101114080)
SOURABH BAKSHI (80101114085)
DHEERAJ GUPTA (80101114015)
KARAN GOYAL (80101114045)
JEEWAN KANIKA (80101114043)
Page 7
LI S T OF F I G U R ES A ND TAB L ES
F ig No Tit l e P a g e No
Fig 1.1 Univ. jamming gripper picking glass. 13
Fig1.2 Univ. jamming gripper picking 14
Fig 1.3 Two Jaw Cam Actuated Rotary Gripper 14
Fig 2.1 Dual Motion Gripper 18
Fig 2.2 Micro Miniature type Gripper-Parallel 19
Fig 2.3 Compact Low Profile Parallel Gripper 20
Fig 2.4 Miniature Rugged Parallel Gripper 21
Fig 2.5 Parallel Gripper of Ultra Light type 22
Fig 2.6 Parallel Gripper with a T-slot 23
Fig 2.7 Rigid Wide Body Parallel Grippe 24
Fig 2.8 Pneumatic Three jaw Parallel Gripper 25
Fig 2.9 Two Jaw Style Toggle Lock Angular Grippers 26
Fig 2.10 Three Jaw Style Toggle Lock Angular Grippers 27
Fig 2.11 Single Jaw Parallel gripper-One Fixed Jaw Style 28
Page 8
Fig 3.1 Universal jamming gripper 30
Fig 3.2 Jamming skin enabled locomotion 32
Fig 3.3 Steps how gripper work 33
Fig 3.4 Close-up of the jamming end effector 34
Fig 3.5 End effecter is (compliantly) pressed upon an object 34
Fig 3.6 Negatively pressurizing 34
Fig 3.7 Jamming end effecter lifting a plastic bottle. 35
Fig 3.8 And a set of keys. 35
Fig 3.9 Components used 36
Fig 5.1 Applications of universal jamming gripper 44
Page 9
T a ble No Tit l e P a g e No
Table 2.1 Details of Dual Motion Gripper 18
Table 2.2Details of Micro Miniature type Gripper-Parallel
19
Table 2.3Details of Compact Low Profile Parallel Gripper
20
Table 2.4Details of Miniature Rugged Parallel Gripper
21
Table 2.5Details of Parallel Gripper of Ultra Light type
22
Table 2.6Details of Parallel Gripper with a T-slot
23
Table 2.7:Details of Rigid Wide Body Parallel Gripper
24
Table 2.8Details of Pneumatic Three jaw Parallel Gripper
25
Table 2.9Details of Two Jaw Style Toggle Lock Angular Grippers
26
Table 2.10Details of Three Jaw Style Toggle Lock Angular Grippers
27
Table 2.11Details of Single Jaw Parallel gripper-One Fixed Jaw
Style
28
Page 10
Table 3.6.1 Comparison between tea, sand and coffee 34
Table 3.6.2 Various components used 35
Table 4.1 Trouble shooting 41
CONTENTS
Page No.
Candidate's Declaration 3
Abstract 4
Acknowledgement 8
List of Figures 9
List of Tables 10
Chapter 1: INTRODUCTION AND BACKGROUND OF THE PROJECT 13
Chapter 2: LITERATURE REVIEW AND SURVEY 16
Chapter 3: PRESENT WORK
3.1 Problem Formulation 29
3.2 Objectives 29
3.3 Design diagram and working 30
3.4 Experimental Set Up 36
3.5 Experimental Procedure 37
Page 11
3.6. Observations 37
Chapter 4: RESULTS AND DISCUSSION 39
Chapter 5: CONCLUSIONS AND SCOPE FOR FUTURE WORK 42
REFERENCES 45
CHAPTER 1
INTRODUCTION
1.1 CONVENTIONAL SYSTEM:-
A mechanical gripper is an end effecter that uses mechanical fingers actuated by a mechanism to
grasp an object. The fingers, sometimes called the jaws, are the appendages of the gripper that
actually make contact with the object either by physically constraining the object with the fingers
or by retaining the object with the help of friction between the fingers. For a Two jaw cam
actuated rotary gripper there is a cam and follower arrangement, often using a spring-loaded
follower which can provide for the opening and closing of the gripper. The movement of cam in
one direction would force the gripper to open, while the movement of the cam in opposite direction
causes the spring to force the gripper to close. The advantage of this arrangement is that the spring
action would accommodate different sized parts. Most mechanical drives used in grippers are
based on cam and followers or rack and pinion gears as force convertors. Cam driven gripper jaws
normally enjoy a relatively large stroke not normally achievable with other gear types. As a prime
mover almost any form of electrically commutated DC servo motor is suitable.Page 12
Fig1.1 - Two Jaw Cam Actuated Rotary Gripper
Page 13
DISADVANTAGES OF CONVENTIONAL SYSTEM:-
For most rotary actuators such as electric motors, the torque can be assumed to be constant over
the complete gripping range. However, when the jaws close the motor stalls. For DC motors this
can result in an excess of current resulting in overheating and eventually burn out. Switching off
the motor current completely is unlikely to be a satisfactory solution especially where a good
quality cam and follower mechanism is used, owing to the likelihood of the object working loose
during motion. Also, thin and delicate materials of very small dimensions are difficult to handle
by the electro-mechanical form of grippers.
1.2 MAJOR FACTORS IN CHOOSING A GRIPPER AND JAW DESIGN:-
ORIENTATION, DIMENSIONAL VARIATION AND PART SHAPE:-
If there are two opposing flat surfaces in the object, then the 2 jaw parallel gripper is desired as it
can handle variations in the dimensions. Jaws may also be designed to handle cylindrical objects
with the same 2 jaw concept. While designing the parallel gripper it is kept in mind that the
retention or encompassing grip requires less force than the friction grip.
PART WEIGHT:-
While a desired operation is performed on the object the grip force must be adequate to secure
the object. Depending on the force requirement, the type of jaw must be designed so that it forms
a part of it. While designing the gripper, it is to be kept in mind that a safety factor to the amount
of force we select must be added and also about the factor corresponding to the air pressure.
ACCESSIBILITY:-
This applies both to the amount of room for the gripper jaws and for the work being performed
on the object. An internal grip is required if the work is to the exterior of the object. Angular
grippers are usually less expensive than parallel jaws but require additional space for the
movement of the jaws.
ENVIRONMENTAL:-
Grippers may be designed for purposes which are required in harsh environment or clean room
applications.
Page 14
RETENTION OF THE OBJECT:-
Depending on the loss in air pressure, the gripper relaxes its grip on the object and hence the
object may be dropped. Many of the spring assisted grippers are designed for this type of
applications.
Universal jamming gripper could satisfy all these condition with some variations in gripper
diameter and the vacuum pressure exerted on it hence showing its advantage over conventional
grippers.
1.3 UNIVERSAL JAMMING GRIPPER
Gripp0ing and holding of objects are key tasks for robotic manipulators. The development of
universal grippers able to pick up unfamiliar
objects of widely varying shape and surface
properties remains, however, challenging. Most
current designs are based on the multi-fingered
hand, but this approach introduces hardware and
software complexities. These include large
numbers of controllable joints, the need for force
sensing if objects are to be handled securely
without crushing them, and the computational
overhead to decide how much stress each finger
should apply and where. Here we demonstrate a
completely different approach to a universal
gripper. Individual fingers are replaced by a single mass of granular material that, when pressed
onto a target object, flows around it and conforms to its shape. Upon application of a vacuum the
granular material contracts and hardens quickly to pinch and hold the object without requiring
sensory feedback. We find that volume changes of less than 0.5% suffice to grip objects reliably
and hold them with forces exceeding many times their weight. We show that the operating
principle is the ability of granular materials to transition between an un-jammed, deformable
state and a jammed state with solid-like rigidity. We delineate three separate mechanisms,
Fig 1.2–Univ. jamming gripper picking glass.
Page 15
friction, suction, and interlocking, that contribute to the gripping force. Using a simple model we
relate each of them to the mechanical strength of the jammed state. This opens up new
possibilities for the design of simple, yet highly adaptive systems that excel at fast gripping of
complex objects. A completely soft and deformable robot is a desirable platform for traversing
unpredictable terrain, navigating through small holes, or even for interacting with humans where
unintentional infliction of harm is of great concern.
One of the primary difficulties in soft robotics is actuation; not only are soft actuators uncommon
but a soft transmission or skeletal structure to extract useful work from the actuator can also be
challenging to design and tune.
Page 16
CHAPTER-2
LITERATURE REVIEW AND SURVEY
In field of Robotics and Automation, many research works have been done by many researchers.
Some of the distinguished ones which are relevant and carry basic information for this paper
have been highlighted briefly.
The concept of a jamming transition was first introduced by Nagel and Liu5 and also
Cates et al. To explain the onset of rigidity in a wide range of amorphous materials,
including dense colloids, molecular glasses and macroscopic granular materials.
Ramesh Kolluru, Al Steward, Micheal J. Sonnier and Kimon P. Valavanis in their paper
on ―A Sensor based Robotic Gripper for Limp material handling ― proved that series of
flat apparel grippers which are based on principle of pressure differential and suction can
pick and place fabric materials reliably and with acute precision without causing any
change to the structural dimensions of the fabric
Junbo Song and Yoshihisa Ishida in their paper on ―A Robust Sliding mode Control for
Pneumatic Servo Systems‖ successfully simulated and applied the results of a robust
sliding mode control scheme for pneumatic servo systems. It is proven that due to many
of the uncertain bounds used in structural properties of pneumatic servo systems which
are used in controllers design and also due to the insensitivity of the error dynamic to
uncertain dynamics, the model is strong and a robust one
Werner Dieterle in his book ―”Mechatronic Systems: Automotive applications and
modern design methodologies” emphasized on the use of Mechatronic systems in field of
agriculture and automobile engineering. The book describes different methodologies for
Page 17
cross disciplinary subjects, different model based mechatronic design systems and
correspondingly the benefits of these technologies
Robert B.vanVarseveld and Gary M.Bone in their paper on ―Accurate Position Control
of a Pneumatic Actuator Using “On/Off Solenoid Valves” have described the
development of a inexpensive, fast acting and accurate position controlled pneumatic
actuator. The paper describes to use On/Off valve using Pulse width modulation in place
of rather costly servo valves. Also the overall efficiency of the actuators is compared with
servo valves efficiency which is obtained by various other researchers
Jiing-Yih Lai, Chia-Hsiang Menq and Rajendra Singh in their paper on ―Accurate
Position Control of a Pneumatic Actuator have experimentally proven that their proposed
control system of single open valve was far more better than the conventional off control
valve strategy which proved that it was better to obtain the desired accuracy in position
without having any mechanical stops in the actuator
Pham DT, Yeo SH (1991) Strategies for gripper design and selection in robotic assembly
has mentioned various strategies which could be useful in creating appropriate grippers
for different environment or working conditions. Int J Production Res 29:303–316
2.1 SURVEY ON GRIPPERS
DUAL MOTION GRIPPER
For either large/small O-rings, or applications where picking or parts or seating is required
automated seal and O-ring assemblies are made. The seals are spread and placed with the
assembly machine with an O-ring placed in dual motion. The dual motion gripper has been made
for part ejection and facilitating seating of parts. With the help of set screw in center the opening
stroke is adjusted.
Page 18
Fig2.1-Dual Motion Gripper
Table 2.1-Details of Dual motion Gripper
Grip Force Around 275 N
Stroke Spread 15 mm
Stroke eject 6.3 mm
Weight 0.56 kg
MICRO MINIATURE PARALLEL TYPE GRIPPER
This type of gripper is generally designed for handling tiny and delicate parts. The Miniature size
facilitates for banks of grippers to be mounted side by side for close centerlines. It has a
scavenge port and thus from the top it can be controlled.
Page 19
Fig 2.2- Micro Miniature type Gripper-Parallel
Table2.2- Details of Micro Miniature parallel type gripper
Grip Force Up to 40 N
Stroke Spread 4.8 mm
Weight 0.02 kg
MINIATURE RUGGED PARALLEL GRIPPER
These types of parallel grippers are small yet rugged. It has two types of grippers whose jaws
ride on Agrology TDC shafts. These grippers are the standards of jaw centering industry which
supply higher gripping force to the amount of weight lifted. These grippers have a guided wedge
Page 20
design offers better strength and repeatability. This type of gripper is best for short stroke length
and high strength applications.
Fig 2.4:-Miniature Rugged Parallel Gripper
Table 2.4:-Details of Miniature Rugged Parallel Gripper
Grip Force 60-97 N
Stroke Spread 4-6.5 mm
Weight 0.08-0.15 kg
Page 21
PARALLEL GRIPPER OF ULTRA LIGHT TYPE
A high grip force to weight ratio is supplied by medium size two jaw parallel grippers supply.
Some of the grippers are made of light weight titanium alloy and for longer life they are stacked
in thickness in order of thousands. This type of gripper also has a guided wedge design that
causes better centering of the jaws and can repeatedly effect longer strokes. For handling robotic
applications with weight issues such grippers were developed.
Fig 2.5:- Parallel Gripper of Ultra Light type
Table 2.5:- Details of Parallel Gripper of Ultra Light type
Grip Force 62-180 N
Stroke Spread 9-13 mm
Weight 0.20-0.32 kg
Page 22
PARALLEL GRIPPER WITH A T-SLOT
Parallel gripper with T-slot rib is designed for picking parts which requires long strokes in a
narrow space. These types of grippers are designed for various stroke sizes ranging from 0.4
inches (10.16 mm) to 1.2 inches (30.48mm).
Fig 2.6:-Parallel Gripper with a T-slot
Table 2.6:-Details of Parallel Gripper with a T-slot
Grip Force 40-180 N
Stroke Spread 10-31 mm
Weight 0.12-0.45 kg
Page 23
RIGID WIDE BODY PARALLEL GRIPPER
The long stroked grippers feature rigid wide bearing design, which is developed for lifting
bulkier materials or when long rigid tooling is needed. When high moment carrying capacity is
needed the jaws are supported on shafts along the full length of the body and are sealed against
the chips or particles. These types of grippers are designed for eight stroke sizes which vary from
0.8 inch (20.32 mm) to 7 inch (177.8 mm). Rigid jaw design and long stoke is offered by such
type of grippers. Synchronous or non synchronized are two different types of jaw versions that is
available in the market.
Fig 2.7:- Rigid Wide Body Parallel Gripper
Table 2.7:- Details of a Rigid Wide Body Parallel Gripper
Grip Force 110-600 N
Stroke Spread 20-180 mm
Weight 0.3-4.5 kg
Page 24
PNEUMATIC THREE JAW PARALLEL GRIPPER
The Three jaw parallel grippers are designed for four models which includes a patented T-slot
design. The gripping strokes has a wide range which varies from 0.2 inch (5.08mm) to 0.9 inch
(22.86mm) and correspondingly the forces varies from 120 N to 1250N.
Fig 2.8:-Pneumatic Three jaw Parallel Gripper
Table 2.8:-Details of a Pneumatic Three jaw Parallel Gripper
Grip Force 120-1250 N
Stroke Spread 5-23 mm
Weight 0.5-6 kg
Page 25
TWO JAW STYLE TOGGLE LOCK ANGULAR GRIPPERS -
In these types of grippers the angular jaw travels an angle of total 180 degrees thus compelling
the jaws of the grippers to retract back completely from the gripping which eliminates another
required axis of travel. The Jaw rotations can be adjusted for a varied angle from -2 to 90 degrees
which is associated with individual jaws and thus makes the gripper suitable for many industrial
applications. Such type of grippers features in two jaw or three jaw design, both of which are fail
safe toggle locking and is -2 degree past parallel.
Fig 2.9:-Two Jaw Style Toggle Lock Angular Grippers
Table 2.9:-Details of Two Jaw Style Toggle Lock Angular Grippers
Grip Force 80-3600 N
Stroke Spread 180 degrees
Weight 0.08-2.8 kg
Page 26
THREE JAW STYLE TOGGLE LOCK ANGULAR GRIPPERS
In such type of grippers a movement of 90 degrees for individual jaw compels the gripper to
move back from the gripping thus eliminating another required axis of travel The Jaw rotations
can be adjusted for a varied angle from -2 to 90 degrees which is associated with individual jaws
and thus makes the gripper suitable for many industrial applications. These types of grippers
offers unique three jaw design, both of which are fail safe toggle locking and is -2 degree past
parallel.
Fig 2.10:-Three Jaw Style Toggle Lock Angular Grippers
Table 2.10:-Details of Two Jaw Style Toggle Lock Angular Grippers
Grip Force 7-900 N
Stroke Spread 180 degrees
Weight 0.5-4 kg
Page 27
SINGLE JAW PARALLEL GRIPPER - ONE FIXED JAW STYLE
These types of grippers have a compact pneumatic gripper actuator provided with t-slot rib
designed to use in close surfaces where large loads are required. Such type of grippers is suitable
where one jaw is positioned to zero. These grippers have a T-slot bearing design which is
supported along the length of the body to bear heavy loads. There are multiple mounting surfaces
on the system which guides loads to be clamped by the top surface or by the gripper end plate.
Such type of grippers are offered in four stroke sizes which has a variable range from 0.2inches
(5.08 mm) to 2.5 inch (63.5 mm) and have corresponding bore sizes of 0.5 and 0.75 inch. On
both sides of the gripper the stroke adjustments are standardized and are sensor ready for
different applications.
Fig 2.11:- Single Jaw Parallel gripper-One Fixed Jaw Style
Table 2.11:- Details of Single Jaw Parallel gripper-One Fixed Jaw Style
Push Force 60-160 N
Stroke 12-51 mm
Weight 0.07-0.25 kg
Page 28
CHAPTER- 3
PRESENT WORK
3.1 PROBLEM FORMULATION
The main problem in handling of the materials in the industry was that it lacked in universal
approach. So, the solution for it was a Universal Jamming Gripper. Universal Jamming Gripper
that served as an alternative to a robotic claw or hand for gripping and manipulating objects. The
gripper is brilliant in its simplicity – essentially, it’s a rubber balloon filled with “granular
material.” To grab hold of an object, the gripper wraps itself around the object and then air is
pumped out of the balloon, forming a tight grasp. To release the object, air is pumped back into
the balloon, loosening the grasp, or even propelling the object a short distance.
3.2 OBJECTIVES
1. To design a Universal jamming gripper with the assumed physical dimensions.
It includes the study of history of different grippers and the physical parameters associated with a
gripper. Parameters such as vacuum pressure required and the volume or size of the gripper.
2. To test different granular materials for jamming gripper.
It includes testing different materials like coffee, tea, and sand for the universal jamming gripper
filling material which could grip materials on creating vacuum through it.
3. To test the gripper in Lab conditions.
The gripper was tested in lab condition which includes gripping different materials with the
jamming gripper in static and dynamic conditions.
Page 29
3.3 UNIVERSAL JAMMING GRIPPER DESIGN DIAGRAM & WORKING
UNIVERSAL JAMMING GRIPPER
INTRODUCTION:
These include large numbers of controllable joints, the need for force sensing if objects are to be
handled securely without crushing them, and the computational overhead to decide how much
stress each finger should apply and where. Here we demonstrate a completely different approach
to a universal gripper. Individual fingers are replaced by a single mass of granular material that,
when pressed onto a target object, flows around it and conforms to its shape. Upon application of
a vacuum the granular material contracts and hardens quickly to pinch and hold the object
without requiring sensory feedback.
Fig 3.1:- Universal jamming gripper
As this system is not yet commercialized its specifications are not yet available. And it varies
with different projects. We will measure our jamming gripper specifications in the analysis part
of this project.
3.3.1 WORKING PRINCIPLE: Jamming is the mechanism by which particulate material can
transition between a liquid-like and a solid-like state. The most commonly experienced form of
jamming can be achieved with a small change in confining volume of the granular material, for
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instance through application of a vacuum. However, in systems comprised of more microscopic
constituents, such as colloids or molecular liquids, temperature is another relevant control
parameter and jamming coincides with the temperature-dependent glass transition. Furthermore,
jamming and un-jamming can be driven by applied stresses, such as shear.
Jamming in its most general form is controlled by three key parameters: the degree of
geometrical confinement (given by the particle packing density), the temperature, and the applied
stress. For this work, the focus will be on jamming occurring due to a pressure differential which
we will call vacuum jamming.
Vacuum jamming is commonly experienced in products such as vacuum packed coffee which is
shipped in a stiff (solid-like) brick. When this brick is punctured, releasing the confining
vacuum, the coffee particles behave liquid-like. Though jamming itself can do no net external
work on the environment to enable mobility, it can be used to modulate the work performed by
another actuator. For instance, consider the simple case of a ball made up of a jam able material
with a balloon in its interior. When the interior balloon is inflated and the jamming medium is in
its liquid state, the balloon can do work through the ball to the environment.
However, when the jamming medium is in a solid state, the balloon does not work on the
environment as long as the jamming medium does not yield. This example is in essence the
mode in which the first robot designed herein operates.
Virtually all particulate (granular) material exhibits the phenomenon of vacuum jamming.
However, the strength of the effect can vary based on the size, shape, and compressibility of the
particles.
JAMMING SKIN ENABLED LOCOMOTION
The effective flexural modulus vs. vacuum level for several commonly available particulate
materials is shown. Cylindrical beams with flexible polymer walls were made filled with each
particle type, and three point bending tests were performed to evaluate how the modulus of these
materials varies with vacuum level. Not surprisingly, the figure shows that large spherical
particles (1.9mm glass spheres) do not exhibit the jammed strength that the rougher shaped
particles exhibit. However, if more liquid-like behavior in the un-jammed state is required, then
spherical particles still exhibit jamming while flowing very well in the un-jammed state. Particle
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choice is then motivated by application; further discussion of this and metrics for liquid-like
behavior have been offered previously.
Fig 3.2 Jamming skin enabled locomotion
The first prototype demonstrated that uses jamming as a mobility mechanism is the Jamming
Skin Enabled Locomotion robotic prototype. A side view diagram of the robot appears in Fig. 2.
The robot is comprised of many cellular compartments that enclose a fluid-filled cavity (in the
simplest case air). The cellular compartments contain jamming material each of which can be
jammed (made rigid) by applying a vacuum or un-jammed (made flexible) by releasing the
vacuum. The central fluid-filled cavity is the only actuator; pumping a fluid into this cavity is the
actuation mechanism. The robot is a good example of the concept of “activators” vs. “actuators”
in that there is only a single actuator (the center cavity) but the robot has a very large number of
degrees of freedom.
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3.3.2 STEPS HOW GRIPPER WORK:
Above fig:-3.3 demonstrate Jamming-based grippers for picking up a wide range of objects
without the need for active feedback.
(A) Attached to a fixed-base robot arm.
(B) Picking up a shock absorber coil.
(C) View from the underside.
(D) Schematic of operation.
(E) Holding force Fh for several three-dimensional-printed test shapes.
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WORKING
1. A close-up of the jamming end effecter. Right now it is (presumably) positively
pressurized and in a liquid-like state.
Fig. 3.4
2. The end effecter is (compliantly) pressed upon an object (medication bottle).
Fig. 3.5
3. Negatively pressurizing changes the end effecter to a solid-like state, latching onto the
object of interest for grasping / pickup.
Fig. 3.6
4. Jamming end effecter lifting a plastic bottle.
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Fig. 3.7
5. And a set of keys.
Fig. 3.8
3.4 EXPERIMENTAL SET-UP:
It consists of following components:
2metre PVC pipe
Nipple ¼ inch
Shower Head
Cotton
Funnel
Tea Granules
Balloon
Pressure Regulator Valve (3 way)
Vacuum Pressure Gauge
Vacuum Pump
Charging Line
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Rubber Seal
Fig 3.9- Components used
3.5 STEP-WISE PROCEDURE:
1. A conical reducer (shower head) was bought to make holder of universal jamming
gripper.
2. Then, copper nipple, was fitted in upper part of reducer.
3. Then, a PVC pipe of diameter 1/4inch was connected to nipple.
4. Then, a balloon of standard size was filled with three different materials (sand, tea &
coffee) in succession with the help of funnel.
5. Then, the balloon was sealed with a rubber seal on upper part of conical reducer with thin
ball of cotton, to prevent the back flow of granular material during suction.
6. A three way pressure regulator valve was taken and its one end is connected to the PVC
pipe, other to the vacuum pressure gauge and third one to the vacuum pump with the help
of charging line.
7. On starting the vacuum pump, with the opening of the valve different readings were
taken on pressure gauge on account of gripping various components.
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3.6 OBSERVATIONS:
3.6.1 Comparison of properties of Tea, Sand & Coffee
Properties Tea Sand Coffee
Density Least More Most
Grain size Large Small Very small
Moisture retaining
capacity
Minimum Medium Maximum
Porosity Maximum Medium Minimum
After suction effect Maximum Medium Minimum
3.6.2 Various components used:
Item Name Weight (gram) Suction
Pressure(lb/inch2)
One Rupee coin 5 8
Nut (1/4 inch) 10 10
Copper Pipe 10 10
Bolt (1/4 inch) 20 13
Wooden Block 30 16
Car key 80 17
Medicine bottle 100 18
Fragile Glass 120 19.5
Iron Solid Cylinder 140 21
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Types of materials being tested:
Ferrous material
Non-ferrous material
Alloys of various metals
Plastics
Glass
Ceramics
CHAPTER – 4
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RESULTS AND DISCUSSIONS
To evaluate gripping performance we performed pick-and-place operations in which objects
were gripped, lifted, and moved.
For better functioning of this project we have to select the best material out of the three granular
materials i.e. sand, tea and coffee. Since, the grain size of sand and coffee is comparatively less
than the grain size of tea granules. Therefore, void space in sand and coffee is small and hence
lesser air quantity is present in voids. Whereas in case of tea there are large voids and hence
larger amount of air can be sucked and hence increases the inner pressure. And helps in effective
gripping of the various components.
So, we select the tea as most suitable granular material on account of its low density, large grain
size and maximum porosity.
The primary goal in these experiments was to demonstrate that our algorithm can identify proper
grasps for the jamming gripper. We compare our learning algorithm with a heuristic baseline
method (which we call ‘centroid’) that always grips the centre of the object. In detail, we subtract
background first to get an approximate region of the object, and then use the centroid of these
pixels as the grasping point. Although this simple rule is effective for small objects, it fails when
the centroid is located off of the object, or is in some place poorly suited for gripping (such as a
phone charger with a long cable). Table I shows the comparison. Snapshots of the jamming
gripper grasping objects. We can see that our algorithm outperforms the ‘centroid’ method with
an average increase in success rate of 18%. For simple-shape objects, such as a pen or a screw
driver, the centre is usually designed to be a good grasping point. Also for small and stable
objects, almost any place on the object is a proper grasp for a jamming gripper. Therefore, both
algorithms perform well in these cases. However, for the ‘charger with cable’ example, the
centroid method failed every time because the centre was either on the cable or off the object.
Our algorithm on the other hand predicted only one incorrect rectangle in this case. Beyond this,
both methods fail at picking up some items because they are outside the capabilities of the
gripper. For example, for unstable objects, the jamming gripper is not always able to pick them
up even with manual control. Even if a flat object is graspable, the sensitivity of its point cloud
(the depth of the object is very similar with the background and thus almost invisible) can affect
our algorithm. Under this circumstance, image-based features are more significant than depth-
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based features in the score function. Consequently, the algorithm tends to find regions with more
changes in colour, usually edges of the object, which are sometimes suboptimal. Thus for flat
objects, the centroid method sometimes performs better than our learning algorithm. A special
explanation is required for the performance of the jamming gripper on the V-shape plastic tongs.
The best grasping position for this item is on its corner, although any location on its legs would
seem like a reasonable grasp point. However, away from the corner the legs bend under the
pressure of the gripper, leading to a failed grip. This is why the prediction correctness of both
algorithms is 100% for the tongs, but successful rate for the physical test is low. In summary, for
stable and non-flat objects that are graspable by the jamming gripper, our algorithm can find
proper grasp for the gripper with high reliability. This represents the first time a jamming gripper
has successfully executed autonomous closed-loop grasping, and with an average increase in
success rate of 18% over a heuristic method. Grasping with jamming and parallel grippers. To
explore the versatility of our learning approach, we also tested grasping the same set of objects
with a parallel gripper with two jaws. We used the same training data to learn the model for this
gripper, but with different labelled grasping rectangles. This is because the good grasps are
different for the two grippers. Unlike the jamming gripper, the parallel gripper’s orientation
would largely influence grasps, so the ‘centroid’ method, where no orientation is predicted, was
not used for comparison. For stable objects such as a pen, our algorithm could not always find a
correct orientation, and some other failures were caused by the limited opening width of the
parallel gripper. The x-axis stands for stability of the object and the y-axis stands for
deformability. The coordinate is only for demonstration, not strictly defined. Better. Some
objects we found the parallel plate gripper could not grasp were: telephone handles, mini-
sculptures, and a round lens cover. One advantage of the parallel gripper is that it is less affected
by an object’s stability or deformability. So for the parallel gripper, unstable and deformable
objects are usually graspable and thus the accuracy on these objects is high. For flat objects as
well, the success rate of the parallel gripper is also higher than the jamming gripper. This is
mostly because the two stiff parallel plates can provide enough friction (even if the contact is of
small size) to hold a flat object. Based on these experimental results, qualitatively demonstrates
the preferred gripper for different objects.
4.1 MAINTENANCE INSTRUCTIONS & TROUBLE SHOOTING:
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1. The valve is removed from the machine and is dismantled, cleaned thoroughly and
reassembled.
2. The tea granules should be fresh and free from moisture and must be replaced after 2
weeks.
3. The problems and troubles are noted and therefore the probable causes and its
remedies from the table are ascertained.
TRO0UBLE SHOOTING:-
1. Leak observed. May be due to hole in PVC pipe or
balloon.
May be due to dust formation in the
valve assembly
Defective rubber seal.
Faulty pressure regulating valve.
Clean the whole assembly.
Replace the rubber seal.
Clean or replace the faulty
valve.
2. Tea granules observed in
PVC pipe.
Defective end cover rubber seal.
Cotton ball layer not placed.
Replace the rubber seal.
Properly place cotton ball
at its place.
CHAPTER -5
CONCLUSION
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From the model we have found out that the universal jamming gripper has many advantages and
is one of the modern techniques in the world of robotics which makes pick and drop work easier
and much faster than the conventional techniques.
Highly dynamic operation and high acceleration possible.
Intermediate positions can be set easily by regulating pressure.
Easy to handle thin sheets and other low dimension materials which require intelligent
handling.
Low cost
The Universal jamming grippers offer the most attractive features and are a common choice and
this explanation can be inferred from the work carried out in the project. The gripper was made
of tea granular material which allowed the gripper to be lightweight, yet durable for machine
loading of metal parts. Such universal jamming grippers are generally cost-effective because
vacuum pumps, valves, and other pneumatic devices are easy to maintain. Different types of
gripping surfaces, gripping materials and different diameters of grippers can be made to test the
gripping force of the universal jamming gripper.
A universal gripper based on jamming may have a variety of applications where some of the high
adaptability of a human hand is needed but not available, or where feedback is difficult to obtain
or expensive. Examples include situations where very different objects need to be gripped
reliably and in rapid succession. A granular system can move with ease from gripping steel
springs to raw eggs, and it can pick up and place multiple objects without changing their relative
orientation. Its airtight construction also provides the potential for use in wet or volatile
environments. Another situation where such a gripper has a significant advantage over traditional
designs is when minimal initial information is available, for example when the detailed shape or
material properties of the target object are not known a priori, or when precise positioning is not
feasible. Because the gripper material adapts and conforms autonomously to the surface of the
target object, a jamming-based system can be expected to perform particularly well for complex
target shapes.
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5.1 FUTURE SCOPE:
5.1.1 AUTOMATION IN INDUSTRY
AUTOMATION is termed as use of different control systems such as numerical control,
programmable logic control or other industrial control systems in concern with computer
applications or information technology (such as Computer Aided Design or Computer Aided
Machining) to manipulate all the industrial machinery and processes, thus reducing the need for
human intervention. As always said, for growth of industries, automation is must and should
supersede the mechanical growth. Where mechanization provides human operators with
machinery to assist them along with the muscular requirements of work, automation decreases
the involvement for human sensory and mental requirements as well. Automation plays a
dominant role in the world economy these days and in daily application in industries. As for
these days, the twenty first century engineers are increasing their research to combine automation
with mathematical and organizational systems to facilitate new complex systems which has wide
applications.
AUTOMATED MANUFACTURING:
Automated manufacturing mainly symbolizes to the use of automation to reproduce things
usually obtained in a factory. The automation technology has many advantages and thus it
influence in the manufacturing and production processes. The main advantages of the automated
manufacturing are higher consistency and quality, reduced lead times, simplification of
production process, reduced man handling & improved work.
HOME AUTOMATION
It is also termed as “Domotics” which represents a practice of increased use in household
automated appliances and residential complexes, where electronic things are used to solve
practically non-feasible things, which were largely expensive or not possible earlier by any
means.
ADVANTAGES OF AUTOMATION:
These day’s human operators are being replaced in many tasks that involve hard
physical, strenuous or monotonous work.
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Replacing humans in certain tasks that is required to be carried in non-safe conditions
which include heat or fire, space outside atmosphere, volcanic eruptions, nuclear reactors,
underwater in sea or ocean, etc.)
Undertaking jobs which are difficult to perform by human beings like carrying heavy
loads, transporting bigger objects, working with too hot or too cold objects or something like
performing a work with high pace or utmost slowness.
Economy improvement is one of the major advantages of the automation system.
Sometimes some kinds of automation system imply improvement in economy of firms,
enterprises or society. Examples may be taken, an enterprise recovering its total investment
which it had incurred on an automated technology, when a state adds up to its income due to
automation like Germany or Japan as in the 20th Century or when the humankind could use the
internet which in turn uses satellites and other automated engines.
5.1.2 ROBOTICS
Robotics is a branch in science and Engineering of robot making which deals with design,
development, manufacturing, application and real time use in day today‘s world. It is related to
three branches mainly which are mechanics, electronics and software development.
Robotic Grippers:-These are the type of robots which have the capability to grasp definite objects
and then reposition it according to requirement. The robotic grippers have two basic parts. They
are the manipulators and end effectors.
The manipulators are the working arm of the robot whereas the End effectors are the hands of the
robot. Generally the robots are connected with replaceable end effectors for which they can
perform wide range of functions with same fixed manipulators. The end effectors are actuated by
various mechanisms which include mechanical drives, electrical drives, hydraulic drives and
Pneumatic drives.
Among this the widely used one is the hydraulic grippers but the most favorable one is the
pneumatic gripper on which this paper is based on.
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Fig 5.1: Applications of Universal Jamming Gripper
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REFERENCES:-
1. Pham DT, Yeo SH (1991) Strategies for gripper design and selection in robotic assembly. Int J
Production Res 29:303–316.
2. Jaeger HM, Nagel SR, Behringer RP (1996) Granular solids, liquids, and gases. Rev Mod
Phys68:1259–1273.
3. Cates ME, Wittmer JP, Bouchaud JP, Claudin P (1998) Jamming, force chains, and fragile
matter. Phys Rev Lett81:1841–1844
4. Trappe V, Prasad V, Cipelletti L, Segre PN, Weitz DA (2001) Jamming phase diagram for
attractive particles. Nature 411:772–775.
5. Internet websites:
www.google.com
http://www.youtube.com/watch?v=Rna03IlJjf8
http://www.youtube.com/watch?v=bFW7VQpY-Ik
http://www.youtube.com/watch?v=NZtRTPf1uk4
creativemachines.cornell.edu/positive_pressure_ gripper
http://www.hizook.com/blog/2010/10/25/jamming-robot-gripper-gets-official-
article-published-pnas
http://www.roboticsbible.com/robotic-universal-jamming-gripper-throws-
objects.html
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