Interaction Force Estimation Using Extended State Observers: An Application to Impedance-Based Assistive and Rehabilitation Robotics

摘要

This letter presents a force observer that estimates the external interaction forces from the measured joint position and joint actuation for a class of robotic manipulators. This is done without an explicit (physical) force or torque sensor, through an extended state observer (ESO) assuming a known model of the dynamics of the manipulator. It is designed to be capable of estimating relatively fast time-varying external forces. The main result shows that the proposed ESO is theoretically able to estimate unknown time-varying external forces to an arbitrary accuracy for any initial condition starting in a given compact set. Simulation results demonstrate the effectiveness of the proposed ESO. Moreover, first experimental evaluations with a healthy subject and a poststroke patient on a rehabilitation robotic platform show the feasibility of the approach in this context and highlight the importance of the quality of the dynamic model.