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  1. 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. 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. 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. 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. 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. 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. 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. 8. Application of electric field Thermal actuation of torque tube
  9. 9. 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.
  10. 10. 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.
  11. 11. 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.
  12. 12. 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.
  13. 13. 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.
  14. 14. 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.
  15. 15. 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
  16. 16. 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.
  17. 17. CAD Model of the Finger
  18. 18. 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.
  19. 19. 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.
  20. 20. Contour Plot 1 Total deformation contour plot
  21. 21. Contour Plot 2 Equivalent ( von-Mises ) stress contour plot
  22. 22. Solution Force convergence plot: Force(N) v/s Cumulative iterations.
  23. 23. Displacement convergence plot: Displacement (mm) v/s Cumulative iterations. Displacement convergence plot: Displacement (mm) v/s Cumulative iterations.
  24. 24. 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.
  25. 25. CAD model for the gripping part of the finger, which is the bottom mould.
  26. 26. Design of the mould for the air chambers, which will expand according to the air pressure.
  27. 27. 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.
  28. 28. 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.
  29. 29. 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.
  30. 30. 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.
  31. 31. 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.
  32. 32. 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.
  33. 33. Removing the Casting from the mould After baking in the hot air oven, the casting from the mould is taken out slowly.
  34. 34. 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.
  35. 35. Demo of pneumatically actuated gripper mechanism
  36. 36. GripperAttachment Four removable fingers with the central hub, designed in Fusion 360.
  37. 37. FANUC M10 iA/12 Robot The robot to which the gripper attachment will be installed in the end.
  38. 38. 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
  39. 39. Thank You Stay Safe