Development of Flow Rate Control Type Quasi-Servo Valve Using Small-Sized On/Off Valves

In a pneumatic driving system, a servo valve is most expensive equipment compared with pneumatic actuators. In a wearable driving system, the mass and size of a valve also becomes serious concern. The purpose of this study is to reduce the burden of the user by using a small and light-weight quasi-servo valve that consists of inexpensive on/off valves and an embedded controller. The relation between input duty ratio and output flow rate of the valve is nonlinear. In the previous study, a pressure control type quasi-servo valve using a pressure transducer was also developed. However, the cost of the valve was increased. In this paper, to develop a lower-cost valve with good controllability, the flow rate control type quasi-servo valve by compensating the input duty-ratio of the valve is proposed and tested. The performance of the tested valve was also investigated. As a result, the valve can generate the proportional output flow rate according to the input voltage.