Output feedback control of integrator systems with disturbance and input saturation

This paper focuses on a tracking control problem of multiple integrator systems subjected to input saturation and disturbance. A novel output feedback nested saturation controller is proposed with active disturbance compensation facilitated by a saturated linear extended state observer (SLESO). This approach is aimed at synthesizing a virtual control input signal in the saturation function that can be derived in a recursive design procedure via SLESO. An invariant set of the virtual control input is deduced via Lyapunov-based analysis, such that the amount of input can always be under a desired input restriction. Further, the conservativeness of the traditional nested saturation controller is avoided by a time-varying parameter adaption law. The proposed controller guarantees a prescribed transient performance and the tracking error can be made arbitrarily small. Furthermore, exponentially asymptotic output tracking can be achieved when the disturbance is constant. Comparative simulation studies show the effectiveness of the proposed method. (C) 2020 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.