A STUDY ON A SOUND OPERATED VALVE FOR A WEARABLE PNEUMATIC SYSTEM

Abstract

A sound operated directional control valve (SODC-Valve) is proposed which opens and closes in response to the sound of a specific frequency propagated inside the gas supply tube and therefore needs no electric wiring to convey the control signals. By using multi-frequency sound, several valves can be controlled simultaneously and resultantly the pneumatic multi-degree wearable system can be constructed compactly. Firstly, the sound-gas pressure converter is proposed and improved so that self-excited vibration can be suppressed. Secondly, the basic characteristic of the sound-gas pressure converter is investigated to show that the back pressure is different depending on whether the sound of specific frequency is added or not. Furthermore, a pilot valve is developed. Because the pilot pressure change of the pilot valve developed is only 20kPa, a main valve is proposed and developed. Finally, a pneumatic multi-degree-of-freedom wearable power-assist system is constructed by using a Dry Ice Power Cell as the portable gas supply, wearable actuators developed in the previous study, and two sound operated directional control valves developed. Experimental results show that the sound operated directional control valve is feasible and practical in the pneumatic multi-degree-of-freedom wearable system.