Bi-directional Soft Robotic Finger Actuated Mechanisms

Abstract

Pressure actuated soft robotic fingers are commonly used in different structures, shapes and orientations for predominantly gras** applications. But soft robot application with two pressure chambers on either side of the restraining material that facilitates curling of the soft robotic finger in two directions when the chambers are actuated alternatively is only found in an attempt to mimic fish tail for its locomotion. This project outlines how the two-chamber finger with bi-directional motion capabilities can actuate mechanisms. It is an advantage to use pressure difference actuated pneumatic tubes over conventional heavy motor actuated rigid cranks in circumstances like tethered robots, ceiling robots, etc. An attempt is made to explain how the soft robot can act as a crank or input link for planar mechanisms such as four-bar mechanism and slider-crank mechanism, through analytical and numerical approach. Simulations of the soft robot has been used to obtain the input (pressure) vs output (curling of the robotic finger) characteristics. The tip of the finger is considered as input to the forward kinematic analysis of the mechanism, i.e., four-bar and slider-crank mechanism. Similarly, inverse kinematics formulations are obtained to obtain the pressure required as input to result in desired rotation of the follower link in a four-bar mechanism and the displacement of the slider in a slider-crank mechanism. Proof of concept prototype of the bi-directional soft robotic gripper has been developed and tested.