Design of a fast response inflatable soft pneumatic bending actuator for wearable robots

Abstract

therefore, they have been unable to provide assistance at desired moments. In this dissertation, an inflatable wrinkle actuator, manufactured based on the devised theoretical model with high-frequency welding fabricating process, provided fast inflation and deflation responses. First, a theoretical model was proposed to develop the actuator that satisfies the design requirements, such as the desired assistive torque and wearability. Second, the deflation time was reduced by designing a pneumatic inflatable exhaust valve. The proposed valve covered a large exhaust area, allowing it to increase the amount of exhausted air compared with commercial pneumatic components, such as solenoid valves or regulators, and tubes with limited exhaust area. Based on the actuator's inflation and deflation response times, it was found that it did not interfere with human joint movements because the air in the actuator did not remain in the actuator after depressurization. Finally, the performance of the actuator was validated by applying it to a soft knee-wearable robot. The developed robot was able successfully to assist in knee motions during static motions (deep squat and front lunge), ground walking, and stair ascending without creating any residual resistance.

Recently, many soft pneumatic actuators (SPAs) have been developed attribute to their inherent compliant components and backdrivability, providing safe human-robot interaction. Inflatable actuators have been prominently exploited in diverse robotic applications due to their theoretical model-based manufacturability and high form factor. In particular, they have been widely used in soft wearable robots to support human joint motions. Although inflatable actuators are lightweight and have fast inflation response, their deflation time has not been rapid enough to enhance the actuator bandwidth