Robust Disturbance-Rejection Design for Systems With Uncertainties, Disturbances, and Noise

This article presents a robust modified equivalent input disturbance (RMEID) design algorithm that effectively attenuates the effects of uncertainties and disturbances on the control output while considering the measurement noise. A robust disturbance-rejection framework is presented including a modified equivalent input disturbance (MEID) estimation and a robust feedback. The MEID approach estimates an equivalent input disturbance (EID) in two steps: Obtaining a prior disturbance estimate and updating the prior disturbance estimate to obtain a posteriori disturbance estimate. Since the MEID compensation for the EID cannot guarantee the stability of a control system, a robust feedback control law is used to stabilize a control system with the MEID-based compensation. The parameters of the RMEID-based control system are obtained by solving linear matrix inequalities, which are derived based on a stability condition and a performance condition. The effectiveness of the approach are demonstrated through a case study involving a mechatronic control system. A comparative analysis with a robust improved equivalent-input-disturbance approach validates the superiority of the RMEID approach.