Robust adaptive stick-slip friction compensation

In this paper, a robust adaptive tracking control scheme is proposed for compensation of the stick-slip friction in a mechanical servo system. The control scheme has a sliding control input to compensate friction forces. The gain of the sliding control input is adjusted adaptively to estimate the linear bound of the stick-slip friction. By introducing the sliding control input, the global stability and the tracking error asymptotic convergence to the predetermined boundary are established via Lyapunov´s stability theorem. The proposed scheme is shown to be robust to variations of the system and/or friction characteristics, and a bounded external disturbance. Computer simulations and experiments on an X-Y table verify the effectiveness of the proposed scheme