IJCAS

In this study, we designed an inflatable soft actuator with a novel pneumatic inflatable exhaust valve to reduce exhausting time. The soft wearable robots using inflatable actuators had limitations in joint movement during exhaus phase due to residual air remaining in the actuators since the exhaust time was long. We proposed the novel pneumatic inflatable exhaust valve by utilizing the pneumatic power transmission to block larger orifices compared with commercial pneumatic valves. Two inflatable layers of the proposed valve were installed at the top and bottom of the actuator layer to cover the large exhaust area. Our actuator’s deflation time was 0.13 seconds using the proposed valves and it was 3.2 times faster than using only a commercial solenoid valve. The -3 dB bandwidth of exhausting air was 4.2 Hz for our actuator. Moreover, the actuator bandwidth was 3.4 Hz from the dynamic response experiment, which was sufficient to cover the human walking frequency. Lastly, we validated our actuator to assist knee movements for ground walking and stair ascending through the developed fully wearable soft knee robot.

Keywords: Fast deflation, pneumatic valve, soft pneumatic actuator, soft robotics, soft wearable robot.