Binary robust adaptive control with monitoring functions for systems under unknown high‐frequency‐gain sign, parametric uncertainties and unmodeled dynamics

Summary In this paper, we propose an adaptive output‐feedback controller for uncertain linear systems without a priori knowledge of the plant high‐frequency‐gain sign. To deal with parametric uncertainties and unmodeled dynamics, we consider a robust adaptive strategy named binary model reference adaptive control , which has the good transient properties and robustness of sliding mode control with the important advantage of having a continuous control signal free of chattering. The effective way of tackling unknown high‐frequency‐gain sign is employing monitoring functions. The developed adaptive control guarantees global exponential stability of the closed‐loop error system with respect to a compact residual set. Moreover, in the absence of unmodeled dynamics, exact tracking of a reference signal can be achieved. Numerical simulations illustrate the efficacy of the proposed approach.