Adaptive Sliding-Mode Motion Control for a Micropositioning Stage

Micropositioning stages are widely used in precision engineering application. In practice, the system plant's parameters are uncertain as the carried objects are changed. Traditional control methods cannot deal with the parameter change of the plant as the controllers are designed based on the nominal plant's parameter values. To control the micropositioning stage to arrive at exact position, it is desirable to have a good adaptiveness to uncertain parameters, which can avoid complicated system identification procedure. Additionally, due to the disturbance in the micropositioning stage, it is a challenging task to achieve precision motion control, which requires good robustness to resist disturbance. To deal with these difficulties, a new sliding mode control scheme combined with an adaptive law is presented in this paper. Numerical simulation studies indicate that the enhanced controller is able to guarantee the adaptiveness to the variation of system parameters of micropositioning stage and can endow the system with enough robustness to resist the disturbance.