Robust model reference adaptive control based on linear matrix inequality

Model reference adaptive control (MRAC) has been used in numerous applications to improve system performance in the presence of system uncertainties. To achieve stringent tracking performance specifications, fast adaptation is required in the MRAC framework. However, fast adaptation with high gain adaptive rates could cause high frequency oscillation in the control response, resulting in system instability. In this paper, a novel method is proposed to improve the transient performance, and to restrain high frequency oscillation of the control signal, without modifying the selected reference model. An error feedback compensator is introduced into the control signal in this method, to restrict the control signal oscillation, caused by the estimate error of unknown parameter. Based on the augmented error dynamics, the compensator is designed as a robust controller. Moreover, the error feedback matrix can be obtained by solving a set of linear matrix inequalities. The control method is applied to a controlled wing rock aircraft dynamics model to verify the effectiveness. Simulation results show that the proposed method allows for fast adaptation with high gain adaptive rates, while eliminating high frequency oscillation and guaranteeing transient performance.