Adaptive fuzzy PID control of high-speed on-off valve for position control system used in water hydraulic manipulators

•A water hydraulic manipulator is designed.•The valve group of water hydraulic high speed on-off valve is designed to control the hydraulic cylinder directly.•The experiment verified that the high-speed on-off valve-controlled cylinder system has good application effect in water hydraulic manipulators.•The adaptive fuzzy PID with dead-area compensation is proposed and significantly improves the control accuracy of hydraulic cylinders. In contrast to oil hydraulics, water hydraulics presents distinct advantages, such as minimal environmental pollution, reduced operational cost, and no chemical reactions. Water hydraulic manipulators are instrumental in maintaining and handling fusion reactors. The valve-controlled hydraulic cylinder system (VCHCS) is the core of the manipulator's actuator. This study focuses on the control of a water hydraulic VCHCS, where tap water serves as the medium, replacing conventional hydraulic oil. The integration of four high-speed on-off valves (HSVs) forms a valve group, supplanting the traditional servo valve and facilitating the precise control of the water cylinder's motion. Given the asymmetrical movement characteristics of the water cylinder, a control strategy employing adaptive fuzzy PID with blind-area compensation (AFBC) for HSVs within the designed VCHCS is proposed. Comparative analyses of control precision are conducted among three methods, single PID, double PID, and AFBC, through both simulations and experiments. The experimental results show that the accuracy of fixed-point position tracking is 0.5 mm. In dynamic position tracking, the accuracy of the AFBC is enhanced from 1.5–2 mm to 0.5–0.9 mm compared to the conventional PID method. The experimental findings affirm the feasibility of HSVs driving the water cylinder directly. Using water as the medium further renders the system more suitable for operations within fusion reactors.