An exponentially stable adaptive friction compensator

This note presents a novel adaptive compensation scheme for Coulomb frictio n in a servocontrol system. An adaptive observer for estimating the unknown Coulomb friction coefficient is also derived on the basis of the Lyapunov technique. In addition, a linearizing control Law is developed tea compensa te for the friction force and obtain the tracking objective. The proposed a daptive compensation guarantees an exponential convergence for state errors and parameter error and the adaptive schemes in [1] and [3] guarantee only an asymptotic (or stable) convergence. Simulation results demonstrate the effectiveness of the proposed method for a single-mass servocontrol system.