Multivalve Configuration for Soft Robotics: Overcoming the Trade-Off Between Speed and Accuracy in Pneumatic Systems

This article describes a new multivalve configuration for achieving both high speed and high resolution in pneumatically driven soft robotic actuators. The proposed method utilizes dual on/off valves with differing orifice sizes in both the charge and discharge paths of the pneumatic circuit. The multiple-valve arrangement provides five states of flow-rate control, which can provide high flow rate for large step changes in pressure, and fine pressure control for precision positioning or force control. Compared with a proportional valve, the proposed method is physically smaller, lower cost, and significantly faster in charging and discharging a soft actuator. The performance of the proposed multivalve system is evaluated using a dual hysteresis control strategy, where the valve combination is dependent on pressure error. The proposed method is experimentally compared with two single-valve configurations, and the results demonstrate a significant improvement in both speed and accuracy. The proposed method is suited to applications that require a fast response between arbitrary set-points and precise control of position or interaction force.