Self-Excited Vibration Valve That Induces Traveling Waves in Pneumatic Soft Mobile Robots

This letter presents a soft compact valve inducing self-excited vibration to be aimed for simplification of piping, power saving and downsizing the total system for pneumatic soft mobile robots generating traveling waves. The presented device is composed of flat tubes, permanent magnets, and restraint parts. It is capable of switching the inner pressure among three isolated chambers alternately and periodically by using the constant air pressure supplied from a single line. In this letter, we describe the driving principle of the valve to switch different chambers automatically, while detecting the pre-set pressure inside each chamber without sensors. The prototype has a flexible sheet structure with a mass of 5.1 g and a thickness of 10 mm, and was examined to induce a self-excited vibration of 0.6 Hz by air supply of 80 kPa. Moreover, it was also confirmed that when the developed valve was mounted on a flexible seat-type mobile, it was possible to propel through a narrow space with 25 mm gap smoothly while generating traveling waves. Finally, the effectiveness of the proposed valve is discussed through the experimental results.