The selection criterion of nominal model in active disturbance rejection control for non-affine uncertain systems

摘要

The active disturbance rejection control (ADRC) for uncertain systems with non-affine control input is studied in the paper. Considering a wide class of uncertainties, the necessary and sufficient condition of the nominal model for the stability of the ADRC based closed-loop system is explicitly presented, which illustrates the basic selection criterion of the nominal model for control systems. Under this proposed condition, the satisfactory transient performance can be ensured by the ADRC design. Via tuning the parameter of the extended state observer (ESO), the tracking error can be bounded in a prescribed range in the entire time domain, and the estimating error will exponentially approach a set bounded by the parameter of ESO. The tuning law of controller's parameters can be further summarized that the feedback gain determines the convergence rate of the design trajectory and the parameter of ESO contributes to the capability of disturbance rejection. Furthermore, the closed-loop system is proved to be semi-global asymptotically stable, which guarantees the steady state performance. The simulations for attitude control of flight vehicles demonstrate the theoretical results. (C) 2019 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.