Large-range dynamic characteristic adjustment of high-speed on-off valve for water hydraulic manipulators based on multistage voltage and double sliding mode control

High-speed on-off valves (HSVs) are highly adaptable and can control proportional flow, making them ideal for water hydraulic manipulators. In this paper, a water hydraulic HSV is specifically designed for water hydraulic manipulators. To enhance the dynamic characteristics of the HSV, a multistage voltage control combined with double sliding mode control (MVSMC) is proposed. A control system based on an H-bridge circuit is designed to implement the MVSMC algorithm. Simulations and experiments are conducted to evaluate the HSV's rapid switching and adjustment of dynamic characteristics. The MVSMC algorithm enables quick switching of the HSV, even under fluctuating driving voltages in simulations. The sliding mode controller can control the dynamic characteristics of the HSV over a wide range by adjusting the pre-opening current and holding current. Experimental results show that, driven by the MVSMC algorithm, the opening time and closing time of the HSV are only 1.2 ms and 1.4 ms, respectively. The total non-adjustable opening time and closing time of the HSV are 0-1.2 ms and 0-1.4 ms, respectively. In other ranges, the switching time of the HSV is adjustable. Compared to conventional pulse width modulation (CPWM) control, the MVSMC algorithm offers extreme switching speed for the HSV. The MVSMC algorithm can adjust the dynamic characteristics of the HSV in a wide range, making it suitable for various working conditions requiring different dynamic characteristics.