Robust friction compensation for precise and smooth position regulation

In this paper, a smooth robust time-varying controller is proposed to regulate a servo-system with stick-slip friction. The controller has the advantage of simultaneously achieving zero regulating error and smoothness of motion. Only an upper bound on the maximum static friction torque is required for controller design. Lyapunov's second method is employed to prove the global asymptotic stability of the closed-loop system. Numerical simulations of regulating a servo-system with friction are presented as illustrations.