A Robust Adaptive Model Reference Impedance Control of a Robotic Manipulator With Actuator Saturation

This paper develops a robust adaptive model reference impedance controller for an n-link robotic manipulator with parameter uncertainties, actuator saturation, and imprecise force sensor measurement. In order to handle the system uncertainties, the adaptive technique and prediction error are used. To reduce calculation complexity, the adaptation law for robot parameters estimation is designed in the joint space. Actuator saturation is also overcome by an auxiliary system, and imprecise force sensor measurement is compensated with utilization of adaptive bounding technique. Moreover, the joint acceleration vector problem, which is nonmeasurable, is covered by the filtered regressor matrix. Using Lyapunov's direct method, as long as two conditions are satisfied the proposed controller ensures the exponential stability of all the signals of the closed loop system; otherwise, the closed loop system is globally stable. Finally, simulations are performed on prototyped robots to analyze and evaluate the established controller as well as to demonstrate the effectiveness of the proposed scheme.