Sliding-mode-based robust output regulation and its application in PMSM servo systems

A robust output regulation of a control system aims at disturbance rejection and reference tracking in the presence of uncertainties. Technically, the control design contains two mechanisms: the compensation of nontrivial steady states caused by disturbances and/or reference trajectories and the stabilization of an error system relative to steady states. Feedforward compensation and the internal model (including an approximate integrator) are the two main techniques for the former, while the latter is on a case-by-case basis. This article studies an alternative sliding-mode-based approach that can address the two mechanisms simultaneously, thanks to the new concept of sliding-mode-based output zeroing manifold. This concept bridges the two widely studied areas: robust output regulation and sliding-mode control. The approach is also verified by its application in permanent magnet synchronous motor servo systems.