Load stiffness adaptive control of electro-hydraulic force system based on dominant pole reference model

LI Zhao-zhao1, JIN Xiao-hong1,2, WANG Kun2, ZHANG Shao-feng2
(1.Key Laboratory of Metallurgical Equipment and Control Technology of Ministry of Education, Wuhan University
of Science and Technology, Wuhan 430081, China; 2.Hubei Key Laboratory of Mechanical Transmission and
Manufacturing Engineering, Wuhan University of Science and Technology, Wuhan 430081, China)

Abstract: Aiming at the problem that the load stiffness change in passive electrohydraulic force system with position disturbance will lead to system instability and poor accuracy, an adaptive control strategy based on dominant pole model was proposed. Firstly, the mathematical model of passive electrohydraulic force system with position disturbance was established. The influence of load stiffness variation on the dynamic characteristics of the system was analyzed. Then an ideal reference model based on the dominant pole and the satisfaction of the requirements of strictly positive real and stable minimum phase system was designed according to the system performance index, and a model reference adaptive controller was designed based on the Narendra stable adaptive controller scheme. Finally, the designed controller was simulated by MATLAB/Simulink software. The results indicate that the adaptive controller based on the dominant pole model can effectively suppress the influence of load stiffness variation, the system can quickly track the command signal within 20.7 ms and has excellent consistency, meanwhile the adaptive system has an amplitude error of 0.005% and a phase lag of 9.58° at 14 Hz, which effectively expands the system bandwidth.
Key words: load stiffness; position disturbance; electrohydraulic force system; dominant pole reference model; model reference adaptive control