Masters Project

Masters Project - Owain Pill

Abstract

Versatile grippers are essential if robots are to interact effectively with the real world. Grippers can take many different forms, but the most common at present are constructed using rigid joints and actuators. Given their rigid structure, grippers of this type are prone to causing damage to the objects they grasp and require complex control strategies to mitigate this risk.

As a result, alternative approaches have been explored. One such approach involves using soft materials such as silicones, which can passively deform and adapt to surfaces and thereby produce grippers less likely to damage the objects being grasped. However, current soft robotic grippers require multiple control inputs to grasp a wide range of objects and thus also suffer from the complexity afflicting rigid grippers.

This report demonstrates that a versatile grasping capability can be achieved using a soft robot with a single control input, thanks to a novel design and manufacturing approach. It thus addresses the problems faced by grippers of more conventional design, by reducing the threat of damage to the object being grasped while simultaneously reducing the complexity of the gripper's control systems. The results of a grasp testing exercise show that the proposed gripper is capable of achieving a stable grip on cylinders ranging in size from 5 mm to 105 mm. This illustrates the opportunity for further development in the geometric design of grippers to allow for increased versatility without added control complexity.

Index Terms: robot grippers, soft robots, pneumatic actuation

Skills Developed

• Design for Additive Manufacturing - The molds for the silicone parts were all 3D printed and so were the test fixture components

• Test Engineering - The testing rigs were fashioned from Ender 3 3D printers that were modified with sensors and mechanical parts. Data recording and presentation was also an important part of the testing.