Development of a pinch-type servo valve embedded in a pneumatic artificial rubber muscle

In this paper, a pinch-type servo valve embedded in a pneumatic artificial rubber muscle is developed. The valve has 3-ports, consists of two flow paths with silicon tubes. Two balls are in contact with the tubes and a rotary cam pushes the balls to control the flow direction and the flow rate. The cam is controlled by an electrical motor. Since there is no pipeline to connect the valve to the pneumatic artificial rubber muscle, the pressure loss is negligible in the proposed system. Therefore, the pneumatic driven system is miniaturized and is suitable for a wearable assistive device which requires an actuator with light-weight and high power-weight ratio. We design the valve which is 105mm in length and 34mm in width. The static characteristics of the valve is measured. The compensation method of the lap condition is proposed. The pressure control experiments using the compensation are executed. The effectiveness of the valve is demonstrated by the experiments.