Development of Small-Sized Flexible Pneumatic Valve Using Vibration Motor and Its Application for Wearable Actuator

Due to the recent ageing and decreasing birthrate of the Japanese society, providing nursing care for the elderly has become very crucial. As a result, it is necessary to develop wearable systems to aid in nursing care. To realize such a system, we require not only wearable soft actuators, but also a compact and flexible control valve that can drive a soft actuator such as a pneumatic artificial muscle. The purpose of our study is to develop a flexible, lightweight and compact control valve which can be safely attached to the human body. In this study, we proposed and tested a new type of control valve. The valve consists of a vibration motor and a check valve that is made of a steel ball and an orifice in a flexible tube. The operating principle of the valve is as follows. The valve is normally closed as a function of the check valve. When vibration is applied, the inner ball in the check valve moves and the valve opens. By giving continuous vibration, the valve can be kept open. As a result, we find that the valve can control a larger flow rate relative to its weight and size. As an application of the tested valve, we apply the control device to a wearable actuator in the form of a McKibben artificial muscle.