Single Pump-Valve Pneumatic Actuation With Continuous Flow Rate Control for Soft Robots

Abstract

Pneumatic actuated soft robots attract increasing interest of the researchers due to the availability and simplicity in actuation. The soft robots driven by soft pneumatic actuators (SPAs) of various active volumes demand pneumatic systems with various range of flow rate. However, the usually bulky and hard-to-carry pneumatic actuation systems restrict the portability, and the air pumps provide constant flow rate which constrained the applications such as soft wearable devices and scenarios require fine flow rate control. In this work, aiming for simplicity, high portability, continuous and small flow rate regulation, the pneumatic actuation system consists of identical integrated soft robotic drivers (iSoRD) modules is proposed, obtaining positive and negative pressure output (−53∼83 kPa) in each module using one-pump-one-valve (4-way/2-position solenoid) design. With the check valves installed and the modular design, pressure holding and flow independence are achieved in each pneumatic branch. The heat generation (37.7 °C) and power consumption (2.95 W per-channel) are measure to verify usability. The continuous and fine flow rate regulation (15 mL/s) is achieved by applying the PID controller on the pump motor, which shows superior performance in signal tracking in comparison with the non-continuous Bang-Bang and Varia-speed Bang-Bang algorithms. With the same control, the iSoRD system reduces the error by 37.5% in comparison to our previous two-pump system. The portability, versatility in wearing, practicality and adaptivity of the system are validated by driving three wearable soft robots, a small gripper and a pollination device. Comparing with the existing, the iSoRD is capable of fine flow rate regulation in both negative and positive pressure range with low power consumption, portability and versatility, which will benefit the pneumatic soft robotic systems with broadened application potential.