Variable Stiffness Strategies for Multi-Segment Soft Robot Actuator

Due to the nature of soft robot manipulator, the modelling and control of its stiffness is crucial for a successful contact and non-contact tasks. The stiffness of soft robot manipulators generally embodies the manipulator's ability to satisfy the desired position and force commands. The goal of this study is to compare and investigate variable stiffness strategies in improving the distal tip stiffness of two-segment soft continuum manipulator which have in-built stiffness chamber constructed via granular jamming. The first step is to characterize the behaviour of the manipulator with the change in pressure to determine the Young's modulus. Then forces and their resultant length change relationship is established and based on the two characterization work, the stiffness matrix is obtained. The result shows that the stiffness matrix obtained is able to reject disturbances at the distal tip of the manipulator and the activation of the in- built stiffness chamber via granular jamming further enhance the stiffness and robustness of the manipulator, giving multiple strategies in improving tip distal stiffness.