A Multimode Flow Control Valve for Simplifying the Driving System of Pneumatic Soft Robots

This study aims to simplify the driving system of pneumatic soft robots by developing a lightweight and small-sized multimode flow control valve (MMFCV). It can be embedded in robots as the components, and thus it requires no conventional valves with large size and heavy mass, which significantly reduced the volume and mass of the driving system. The valve is comprised of an input port, an output port, a positive port, and a negative port. By designing the connection of these ports to the actuators, the MMFCV can work in three different modes: one-direction delay mode, delay deflating mode, and double-port control mode. The pressure output characteristics of the MMFCV are modeled, and the validity is verified through experiments. In addition, a robot that comprised of two radial expansion modules, one axial expansion module, and four MMFCVs are fabricated, and the body is driven by the air pressure from the air supply through only one tube. The results of the pipe crawling experiments demonstrate that the MMFCV with multimode increased the flexibility of circuit and time sequence of the air flow, which can reduce the number of the tubes from the air supply to the robot. As a result, it reduced the load pulled by the tubes, and prevented the mission failure from the risk of entanglement of the tubes.