Prescribed disturbance observer-based adaptive dynamic surface control for a voice coil motor servo gantry

High precision tracking of mechatronic systems is often subject to the adverse impact of various disturbances. In this article, a novel prescribed disturbance observer-based adaptive dynamic surface control scheme is proposed to solve the tracking control problem for a class of uncertain nonlinear systems with both mismatched disturbances and matched disturbances. More specifically, the dynamic surface control technique is introduced to eliminate the explosion of complexity problem in the existing backstepping-based design. The prescribed disturbance observers with pre-specified estimation accuracy are first designed to handle the mismatched disturbances, and the adaptive laws are synthesized to deal with the parametric uncertainties and the bound of matched disturbances. Moreover, it can be shown that the tracking error converges to an arbitrarily small neighborhood of zero. Finally, the proposed control algorithm is applied to a customize-designed high-precision motion stage driven by voice coil motors, where numerical simulations and real-time experiments demonstrate excellent tracking performance and disturbance rejection capability, achieving tracking precision error less than 0 . 5 & PTSTHOUSND; in multifrequency trajectory tracking.