Asymptotic Prescribed Performance Tracking Control of Electro-hydraulic Servo Systems under Matched and Unmatched Disturbances

For the coexistence of matched and unmatached disturbances in electro-hydraulic servo systems, a new high-precision motion tracking strategy was proposed, where the needs of transient and steady-state performance were all taken into account. A valve-controlled electro-hydraulic position servo system was chosen as the example, the nonlinear mathematical model including matched and unmatched disturbances was established, prescribed performance function was defined to plan the control errors, and the planned conversion errors were used for backstepping design, while a new continuous asymptotic control technology was integrated to deal with the matched and unmatched disturbances based on the estimation of disturbance upper bound. Finally, the pre-designable transient performance and asymptotic steady-state performance were obtained, and the stability proof was derived via Lyapunov analysis. Tracking experiments under two position commands show that compared with PID and feedback linearization control, tracking accuracy in the initial stages is improved by over 22.9%. Compared with the controller only containing prescribed performance function, tracking accuracy in the steady-states is further improved by over 42.9%. © 2022 China Mechanical Engineering Magazine Office. All rights reserved.