The lobster-inspired antagonistic actuation mechanism towards a bending module

This paper describes a new type of bending module inspired, in part, by the musculoskeletal structure of the lobster leg joint. The bending module proposed combines enhanced torque output, reconfigurability in assembling, safe compliant actuation, and accurate control on its mechanical performance. In this module, antagonistic soft chambers are enveloped by exoskeleton shells, and the bending angle and the stiffness can be independently adjusted by controlling the input pressure in the two chambers. Theoretical models are developed to characterize the relationships between the input pressure, bending angle, and stiffness, and a controller for angle control and stiffness tuning is constructed with experimental validation. The fabricated module can reach the maximum torque output of 109.7 N•mm under 40 kPa and the stiffness range from 40 to 220 N•mm / rad, demonstrating its capacity to fulfill both safe interactions and forceful tasks.