Major Project

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

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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

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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

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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

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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.

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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.

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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)

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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

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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

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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

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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

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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

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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.

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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.

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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

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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.

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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.

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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

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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

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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

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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

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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

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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

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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

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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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