Self-Pumping Actuation Module and its Application in Untethered Soft Robots

Abstract

<p>Pneumatically driven soft actuators have been widely used in soft material robotics. However, soft pneumatic actuators are usually tethered to a rigid pump or compressor, which is complicated, cumbersome and noisy. In this study, we present a novel self-pumping actuation module which is composed of a soft origami pump, two soft pneumatic actuators, a servo motor, a controller and battery. During a working cycle, the soft pump is compressed or restored by pulling or releasing the tendons using the servo motor. As a consequence, the pneumatic actuators connected to the pump generate bending and restoring deformations. Moreover, the air flow inside the proposed module is closed-loop without exchanging air with the environment, making it possible to operation in certain scenarios such as in underwater or vacuum conditions, the advantage of our designed self-pumping actuation module is to recycle air without relying on a large rigid air pump. Theoretical model of the self-pumping actuation module is derived and its performance is characterized via several experiments. The maximum bending speed by the soft actuator is 239.2° s−1, the maximum compression speed of origami pump is 38.2 mm s−1, the maximum pressure inside the pump is 48 kPa, the maximum internal flow rate of pump is 11.5 L min−1, and the maximum torque of actuator is 0.0455 N·m. A soft robotic gripper, a fully untethered quadrupedal soft swimming robot and a rehabilitation glove are fabricated to show the superiority of the proposed design over traditional pneumatically actuated soft robots.</p>