Fast switching and dynamic characteristics preservation of water hydraulic high-speed on-off valve using pressure-adaptive multistage voltage and sliding mode control

Abstract

Water hydraulic high-speed on-off valves (WHSVs) are crucial for managing fluid flow in water hydraulic manipulator systems. As the ambient pressure changes, the dynamic characteristics of WHSVs are affected, which reduces the overall control accuracy of the manipulator. To simultaneously achieve rapid switching and maintain consistent dynamic behavior of WHSVs under variable ambient pressure, a pressure-adaptive multistage voltage and sliding mode control (PMVS) algorithm is proposed. A sliding mode controller is utilized to precisely regulate the coil current at the pre-opening and holding current levels, significantly shortening the switching time of the WHSV. By optimizing the controller’s operation time and modifying the duty cycle of the excitation voltage, the switching time remains stable across different pressures. Based on the structure of the designed WHSV group, an innovative method combining a pressure sensor and a vibration sensor is proposed to capture the dynamic characteristics of the WHSV. Experimental validation demonstrates that the PMVS method efficiently controls the switching delay and regulates the excitation voltage. Dynamic characteristic tests of WHSVs under different pressures are conducted. The results show that PMVS effectively reduces the switching time of WHSVs. Comparative tests reveal that WHSVs driven by PMVS achieve an 86.3 % reduction in opening time and an 87.5 % reduction in closing time compared to conventional pulse width modulation (CPWM). Furthermore, PMVS ensures consistent dynamic characteristics within an ambient pressure range of 0 to 20 MPa, with an opening time deviation of 7.94 % and a closing time deviation of 3.03 %. The PMVS algorithm enables the WHSV to rapidly switch and preserve dynamic characteristics under variable ambient pressures.