Design of an Inflatable Wrinkle Actuator with Fast Inflation/Deflation Response for Wearable Suits

In recent years, inflatable actuators have been widely used in wearable suits to assist humans who need help in moving their joints. Despite their lightweight and simple structure, they have long inflation and deflation times, which make their quick use difficult. To resolve this issue, we propose an inflatable wrinkle actuator with fast inflation and deflation responses. First, a theoretical model is proposed to develop an actuator that satisfies the design requirements: the desired assistive torque and the foam factor based on the wearability. Second, we reduce the inflation and deflation times by partially controlling the actuator layers and by designing pneumatic circuits using a vacuum ejector. To validate the usability of the actuator in wearable suits, we applied it to a wearable knee suit, and the inflation and deflation times were 0.40 s and 0.16 s, respectively. As a result, we ensured that the actuator did not interfere with human knee joint movement during walking by creating any residual resistance.