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In the pneumatic driving system for a soft mechanism, a control valve is the most heavy and expensive device. To realize a compact and inexpensive pneumatic driving system, it is necessary to reduce the size, weight, and cost of the control valve. In the previous study, a low-cost 4-port servo valve that could control the flow rate by changing the bending angle of the buckled tubes was proposed and tested. However, the buckled tube in the valve became the least durable component. The speed at which the valve altered the flow rate was affected by the motor rotational speed and available buckled angular range of the tube. It is necessary to develop a valve that can be operated via a smaller rotational angle, with a durable opening and closing mechanism. In this study, a small-sized servo valve that can control the flow rate via a diaphragm and gate mechanism, driven by a low-cost RC servo motor, is proposed and tested. The tested valve comprises a tiny RC-servo motor, two gate mechanisms, and diaphragms. The gate mechanism contains supply, exhaust, and output ports that connect with each other through a V-shaped groove for the pipeline. Two steel balls are set over the supply and exhaust ports through a diaphragm. By altering the pushing force to both gates using an RC servo motor, the valve can control the supply and exhaust flowrates. In this paper, the construction and operating principle of both valves are described. The output flow rate characteristics of the tested valves are also reported. As a result, it can be confirmed that the tested valve can control the supply and exhaust output flow rate, without any complex mechanical sliding parts, while maintaining a seal.
Research papers (academic journals)
