An IMC based enhancement of accuracy and robustness of impedance control

An accurate and robust impedance control technique is developed based on internal model control structure and time-delay estimation: the former injects desired impedance and corrects dynamics estimation error; the latter estimates and compensates the nonlinear dynamics of robot manipulators. Owing to the simple structure, the proposed control is designed without requiring entire dynamics computation or complex algorithms. The accuracy and robustness of the proposed control are verified using a two degrees of freedom robot with stiff wall simulation. The proposed control realizes desired impedance accurately compared with other competent controllers throughout the task, i.e., free motion, constrained motion, and transition between these motions. Further, proposed control realizes four sets of desired impedance accurately. Thus, accuracy and robustness of proposed control is confirmed.