Design and verification passive compliance leg with micro pneumatic prop for legged robot

Abstract

The passive compliance plays a crucial role in steady and secure locomotion of the legged mammal. This paper aims to introduce the elastic element into the traditional high rigid leg structure to mimic the passive compliance capacity of the animal’s leg joint. For this purpose, based on the analysis of physiological structure of dog leg, the principle of passive compliance leg is proposed firstly. Further more, the single-edge dual-piston pneumatic prop characterizing by small size, large stiffness and high integration is designed and used to connect the thigh component in series with the calf by means of the added anti-torque arm. Finally, the effectiveness of the new structure is validated through the experiments on the single leg physical platform as well as the results from simulations. All results show that with the help of this passive compliance the impact force between the ground and robot feet can be effectively buffered no matter the actuator with poor responsiveness. In the meantime the motion stability and foot trajectory tracking accuracy are also effectively improved in both position control and force control.