Force Observer-Based Admittance Control Design for Robot Manipulators

Abstract

This paper proposed a novel admittance controller for robot manipulators suffering from nonlinear dynamics and force disturbances without contact force sensors. A nonlinear observer is designed to simultaneously estimate both contact force and unmeasurable joint velocities. These estimated values are fed back to the model-based admittance control framework which includes the outer admittance control loop and inner position control loop. Simulation with a two-degree-of-freedom (2-DOF) manipulator is conducted to verify the effectiveness of the proposed algorithm.