soft robot gripper

1. Design & Fabrication of soft robotic gripper for handling
fragile objects
Presented by
Group No-6
Ashraf Raza Rohit R R
Rohan N Kalal P Sai Srinivas
Project Guide
Dr.Vishwanth Koti

2. INTRODUCTIO
N
 Soft Robotics is a sub field of robotics dealing with
construction of robots using highly flexible materials.
 Soft robots are primarily composed of easily deformable
matter such as fluids, gels, and elastomers that match the
elastic and rheological properties of biological tissue and
organs.
 In contrast to robots built from rigid materials, soft robots
are
 Flexible
 Adaptable
 Improved safety
 These characteristics are used in the field
of manufacturing and medicine.
What is Soft Robotics?

3. WHY SOFT ROBOTICS?
 Soft robotics are able to perform tasks simply impossible to complete before without the
input of human work.
 According to Bastian Solutions Global Material Handling System Integrators, by using
precise and inexpensive soft robotics, distribution centers can reallocate the 65% of
labor that is currently dedicated to the handling of delicate edibles.
 Thus, soft robotics will make distribution processes more efficient, decreasing
production costs for affected companies.
 Apart from creating more efficient production processes, soft robots address the
problem of wear and tear that robots with hard structures face.
 The material-derived resilience of soft robots lessens the effects of wear and tear,
making them more appealing to manufacturers looking to subject their machinery to
considerable daily strain.

4. PROBLEM STATEMENT
• Grocery stores deal with fragile inventory every day, such as fruits and
vegetables which are irregular in shape, and boxes and cans that are
vulnerable to damage.
• In many of the cases the objects must be untouched by hand while
packing to stop spreading dangerous diseases like COVID-19. This is
also known as contactless packaging.
• To achieve this the robotic gripper handling the objects must be non-
toxic and must be highly adaptable to the shape of the object being
packed.
• As the e-commerce industry is spreading very fast in India, there is a
necessity to improve the efficiency of the workers and cut down on
labour costs with the help of human friendly robots.

5. LITERATU
RE
SURVEY
About the gripper material
About the gripper material
Mechanical design consideration
Mechanical design consideration
Methods to control the gripper
Methods to control the gripper
Applications of soft robotics
Applications of soft robotics

6. ABOUT THE GRIPPER MATERIAL
 It is non-reactive, stable, resistant to
extreme temperatures (-55 °C to 300
°C )
 Tensile failure stress of 1.4 MPa – 10.3
MPa.
 Elongation of more than 700%.
 Density: 0.9 - 1.2 g/cm3
 Easy to shape and manufacture.
Silicone rubber is an elastomer composed of silicone (a
polymer) containing silicon together with carbon, hydrogen and oxygen.
Silicone rubber is an elastomer composed of silicone (a
polymer) containing silicon together with carbon, hydrogen and oxygen.

7. METHODS TO CONTROL THE
GRIPPER
 Electric field – Usage of high voltage electric field to change the
shape of the gripper like Dielectric Elastomer Actuators (DEA).
 Thermal - Shape Memory Polymers (SMPs) and Shape Memory
Alloys (SMAs) are used to serve as an example of thermal actuation
like nitinol wires.
 Pressure difference - Relies on changing the pressure inside the
flexible air chambers through the use of pneumatic valves.

8. Application of electric
field
Thermal actuation of
torque tube

10. MECHANICAL DESIGN
CONSIDERATION
FOR GRIPPER MATERIAL
 The material must be able to sustain repetitive
compression and decompression.
 It must be able to sustain extreme temperatures and
weather conditions.
 The gripper material must not react with the atmosphere
and the objects which it is grasping.

11. APPLICATIONS OF
SOFT ROBOTICS
1.Climbing Robots
• These robots can reach where humans cannot and that makes them particularly interesting.
• They have the potential to be used at great heights for conducting inspections,
maintenance work in high-rise buildings and even search and rescue missions.
• Some climbing robots are designed to bend when they move, just like caterpillars. These
kinds of robots are particularly helpful in climbing walls of high structures.

12. 2. Wearable robots
• Biomimetic devices include robots that can help
patients while they are recovering from injury and
undergoing physical rehabilitation.
• These robots mimic the natural movement of the
patient’s body wherever placed. This helps the
patient to regain normal motor movements if they
have been affected due to an accident.
• A soft robot that can be used at home hand
rehabilitation is improving the quality of
rehabilitation therapy.

13. 3. Robotic Muscles
• Robotic muscles are being developed in the most
innovative ways that are possible.
• One method draws inspiration from Origami
(Japanese art of folding paper into different
shapes).
• One folded structure of the robotic muscle is
designed to lift as much as 1000 times its weight.
• These muscles can be scaled from a few millimetres
to up to a meter in length.

14. 4. Bio-Mimicry
• An application of bio-mimicry via soft robotics
is in ocean or space exploration.
• In the search for extraterrestrial life, scientists
need to know more about extraterrestrial bodies
of water, as water is the source of life on Earth.
• Soft robots could be used to mimic sea
creatures that can efficiently maneuver through
water.

15. FEATURES OF OUR ROBOTIC GRIPPER
 As discussed earlier in the problem statement, there is a need to design a soft gripper that
can handle any irregular shaped objects which are vulnerable to damages.
 The gripper can be used in warehouses of online grocery stores like BigBasket and
Grofers for pick and place and packaging applications where objects of different shapes
must be handled efficiently and without damaging them.
 Our gripper is highly flexible and can adapt to grasp any object shape up to 15cm of
cubic dimension.
 The end effector consists of 4 flexible fingers which are pneumatically actuated and a
clamp to connect to the robot.
 Due to its modular design the fingers can be replaced individually, without the need to
replace the whole end effector at once.
 Due to its ability to sustain high pressures up to 0.5MPa, the gripper can grasp the
objects weighing up to 8Kgs.

16. SCOPE OF
WORK
CAD modelling of the finger
CAD modelling of the finger
CAD modelling of the moulds
CAD modelling of the moulds
3D printing of the moulds
3D printing of the moulds
Fabrication of Gripper assembly
Fabrication of Gripper assembly
Optimizing the pneumatic pressure
Optimizing the pneumatic pressure
Testing of Gripper for various shapes
Testing of Gripper for various shapes

17. CAD Model for Finger
 The finger for the gripper is designed in FUSION 360.
 The finger consists of air chambers which will be filled with highly pressurized
air and projections for better gripping on the grasping side.
 The following video shows how the finger looks from inside.

18. CAD Model of the Finger

19. Analysis of Finger
ANSYS Static Structural
 Physics Reference: Non-linear mechanical
 Inflation : Inner air chamber surfaces
 No. of steps : 50
 Time step size: 0.001s
 Step value: 0.01 MPa.
 Iterative solver with large deflection control ON.
 Nonlinear Control : FULL N-R method.

20. Boundary Conditions
1. Fixed Support on one face.
2. Displacement – ( 0, 0, Free ) mm.
3. Pressure – Max pressure of 0.5 MPa applied on inner air chamber faces.

21. Contour Plot 1
Total deformation contour plot

22. Contour Plot 2
Equivalent ( von-Mises ) stress
contour plot

23. Solution
Force convergence plot: Force(N) v/s Cumulative iterations.

24. Displacement convergence plot: Displacement (mm) v/s Cumulative iterations.
Displacement convergence plot: Displacement (mm) v/s Cumulative iterations.

25. CAD Model of Moulds of the Finger
 For manufacturing the finger, the Silicone Rubber needs to be cast to get the final
shape.
 For this casting process, moulds are necessary which needs to be customized in
accordance with our design.
 These moulds must designed and 3D printed.
 These moulds are designed in FUSION 360.
 The following figures show the CAD models of the moulds of our finger.

26. CAD model for the gripping part of the finger, which is the bottom mould.

27. Design of the mould for the air chambers, which will expand according to the air
pressure.

29. 3D Printing of the
Mould
3D Printing
The material used for 3D printing of our
mould is Poly Lactic Acid (PLA).
The company of the 3D printer is Creality
Ender 3.

30. Final Moulds for Casting
These are the final parts of the 3D printed moulds which needs to be
assembled, in which the silicone rubber is poured.

31. Mixture Preparation for Silicone Rubber
 We have used EcoFlex 00-30,as our
brand for Silicone Rubber which
contains 2 parts; Part-A and Part-B.
 These parts are mixed in the ratio of
1:1 to get the required material.

32. Stirring of the
mixture
stirring
After mixing both the parts, the material has
to be mixed thoroughly to obtain uniformity.
The process of mixing is carried out with the
help of a magnetic stirrer for about 5 minutes.

33. Pouring Silicone rubber into the mould
The moulds are sprayed with Easy Release Spray
for easy removal of the casted finger
After mixing thoroughly in the magnetic Stirrer,
the material is then poured into the mould slowly
on a flat surface for levelling, so that it does not
form the bubbles.

34. Baking of the mould and the casting
The mould and the casting are then baked inside a
hot air oven for about 4 hours at
60 o
C.

35. Removing the Casting from
the mould
After baking in the hot air oven, the casting from the
mould is taken out slowly.

36. Iterations
• Blow holes on the casting due to non-
homogeneity.
• Thermal deformation of the mould material
(PLA) due to excess baking temperature of
more than 60 0 C.

38. Demo of pneumatically
actuated gripper
mechanism

39. GripperAttachment
Four removable fingers with the central hub, designed in Fusion 360.

40. FANUC M10 iA/12 Robot
The robot to which the gripper attachment will be
installed in the end.

41. REFERENCES
• Wang, Z., Torigoe, Y., & Hirai, S. (2017). A Prestressed Soft Gripper: Design, Modeling, Fabrication,
and Tests for Food Handling. IEEE Robotics and Automation Letters, 2(4), 1909–
1916. doi:10.1109/lra.2017.2714141
• Hirose, S., & Umetani, Y. (1978). The development of soft gripper for the versatile robot hand.
Mechanism and Machine Theory, 13(3), 351–359. doi:10.1016/0094-114x(78)90059-9
• Rus, D., & Tolley, M. T. (2015). Design, fabrication and control of soft robots. Nature, 521(7553),
467–475. doi:10.1038/nature14543
• Majidi, C. (2014). Soft Robotics: A Perspective—Current Trends and Prospects for the Future. Soft
Robotics, 1(1), 5–11. doi:10.1089/soro.2013.0001
• Mosadegh, B., Polygerinos, P., Keplinger, C., Wennstedt, S., Shepherd, R. F., Gupta, U., …
Whitesides, G. M. (2014). Pneumatic Networks for Soft Robotics that Actuate Rapidly. Advanced
Functional Materials, 24(15), 2163–2170. doi:10.1002/adfm.201303288
• Hao, Y., Gong, Z., Xie, Z., Guan, S., Yang, X., Ren, Z., … Wen, L. (2016). Universal soft pneumatic
robotic gripper with variable effective length. 2016 35th Chinese Control Conference
(CCC). doi:10.1109/chicc.2016.7554316

42. Thank You
Stay Safe