Disturbance observer-based repetitive control with application to optoelectronic precision positioning system

•The proposed IRC can mitigate the undesired magnitude amplification at non-repetitive frequencies.•The proposed IRC can correct the undesired deviation at repetitive frequencies.•The DOB-based IRC method provides a universal scheme for periodic and aperiodic disturbances.•The stability, robustness, and parameter guidelines of the proposed method are analyzed.•A discrete implementation of the proposed scheme is verified in an optoelectronic precision positioning system. Rejection of periodic disturbance and/or tracking of periodic reference is of importance in high-precision control systems. Conventional repetitive control is often used to solve the problem, but it cannot precisely set effective frequency points and adversely amplify the non-periodic component disturbance. Therefore, it is not applicable in actual systems where external disturbances exist in the whole frequency domain. In this paper, we propose an improved discrete-time repetitive control method based on the disturbance observer to correct the undesired deviation at repetitive frequencies and mitigate the amplification of the non-components. Moreover, in the observer structure, an intuitive and flexible Q-filter design is presented to suppress low-frequency broadband and intermediate-frequency narrowband disturbances. The conditions of closed-loop stability, performance analysis, and the implementation of the proposed scheme are provided in detail. Finally, the effectiveness of the method is verified by simulation and experimentation on an optoelectronic precision positioning system under the condition of disturbances, and the disturbance suppression and tracking error attenuation are improved.