Improved Adaptive Output Feedback Controller for Flexible-joint Robot Manipulators

This paper presents an improved adaptive output feedback tracking controller for the flexible-joint manipulators with parametric uncertainties. Based on the singular perturbation theory and integral manifold theory, the dynamic system of flexible-joint robot manipulators is decoupled into a slow subsystem and a fast subsystem. An improved adaptive control law is designed for the slow subsystem, and a general class of saturation functions is invoked to design the fast sub-controller. Furthermore, to carry out the whole control system with only position measurements, an approximate differential filter is involved to generate pseudo velocity signals for both links and motors. In addition, an explicit but strict stability proof of the control system is presented. Finally, simulation results verify the superior tracking performance of the proposed controller.