Hybrid Control of a Six-Degree-of-Freedom Robot Arm Using Dynamic Impedance

This paper proposes a hybrid control method for a 6-DOF robot arm using dynamic impedance to achieve stability, high precision, and robustness simultaneously. Conventional impedance control with fixed inertia, viscosity, and stiffness values lacks robustness against changes in working conditions. The proposed method designs an impedance model for the end-effector and performs position control by adding force-based displacement corrections to the target position for force-controlled axes. Dynamic impedance is realized by relating impedance characteristics to joint angles and angular velocities through the final value theorem and quadratic form transient response analysis. MATLAB/Simulink simulations of wall-wiping motion using an RPY-type 6-DOF robot verify the effectiveness of the proposed method.