Contact Force Estimation and Regulation of a Position-controlled Floating Base System without Joint Torque Information

A floating base system is inevitably to contact the environment while it is moving. This paper explores the contact force estimation and regulation algorithm for a position-controlled floating base system without joint torque information. First, the joint space dynamic model of the system is presented and transformed into the contact space. Then, the inverse dynamics method is employed to estimate the contact forces. After that, a proportional-integral (PI) regulator is designed to drive the contact forces to track the desired values. Finally, the feasibility of this algorithm is demonstrated on a simulated bipedal platform.