Parameter Estimation and Adaptive Control for Servo Mechanisms With Friction Compensation

This article presents a new adaptive parameter estimation method and the corresponding control design for nonlinear servo mechanisms with friction compensation. A continuous friction model is employed to capture the friction dynamics of servo mechanisms. Then, the unknown system parameters including friction model parameters are online estimated via the derived adaptive law. Hence, a new adaptive law is proposed to achieve faster and more accurate parameter estimation over classical adaptive laws so as to suppress the undesired transient dynamics. For this purpose, an auxiliary filter is introduced to extract the estimation error for driving the parameter updating law. Moreover, an adaptive control is designed in conjunction with a robust integral of the sign of the error feedback term to address the bounded disturbances and enhance the tracking precision. Simulations and experiments are given to validate the efficiency of the developed control scheme.