Abstract: In the multi-way valves controlled by proportional solenoid valves, the pressure at both ends of the main stage spool cannot be measured in real time, which makes it difficult for modern control technology to be applied to the displacement control of the main stage spool. Therefore, the characteristics of the control system were analyzed first. Based on the fact that the hydraulic dynamics of the control system is much faster than the mechanical dynamics, a reduced-order model is established to avoid the immeasurable problem of state variables. Then, an adaptive robust controller is designed to deal with the uncertain parameters and disturbances in the reduced-order model. The role of the adaptive control algorithm is to estimate and compensate for the low-frequency component of uncertainty. The role of the robust feedback algorithm is to effectively suppress the high-frequency component of uncertainty. The stability of the designed control algorithm is proved by the Lyapunov theory, and the convergence of the maximum tracking error is quantitatively analyzed. Finally, a test platform is established to verify the feasibility and effectiveness of the proposed control algorithm. The experimental results show that the control performance of the developed algorithm is significantly better than that of the commonly used Proportional-integral-derivative(PID) controller. In the medium and small amplitude step response tests, the response time is reduced by more than 20% and the steady-state error is reduced by more than 48%. In the triangular wave test, the maximum tracking error is reduced by 53%, and the displacement hysteresis is less than 1%.

Key words: multi-way valves, reduced-order model, adaptive control, robust control