A flow visualization of a liquid crystal was conducted under the application of an electric field in a mini cylinder with electrode strips on the inner surface. Three-phase alternating currents were used as rotation electric fields to generate the rotational flow of the liquid crystal. A pump with a spiral flow channel was designed based on the rotational flow mechanism of the liquid crystal by using the three-phase alternating currents. The relation between the maximum pressure and the shape of the flow channel in the pump was investigated for various amplitudes of electric fields. Furthermore, pressure-flow rate characteristics of the pump were measured. The maximum pressure increased when we used a liquid crystal with a high dielectric constant for the constant voltage. Dimensional analysis was conducted to arrange the characteristics of the present pump simply and the non-dimensional flow rate and pressure were almost on one line. The size of our pump can be decreased by further research. This study contributes to the development of a micro-pump in micro-fabricated systems and our pump eliminates mechanical vibration and noise.

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A pneumatic cylinder system has been diffcult in position control due to the nonlinearity of the air, friction on packing seal, and parameter variations. Variable Structure Control (VSC) with a proportion valve has been used to overcome the diffcult. However, VSC with an ON/OFF valve is not extensively investigated so far. Therefore, friction compensation using VSC with an ON/OFF valve is proposed in this research. VSC with an ON/OFF valve is designed based on VSC for the proportional one. The experimental results provided the accuracy with 0.1mm as same as using a proportional valve with chattering reduction. The results imply that the ON/OFF valve controlled by VSC is a possible replacement of proportional valve for conventional pneumatic cylinder control system.

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A sound operated directional control valve is proposed in order to widen the application of pneumatic drives to a multi-degree wearable system. The proposed valve 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 signal. By using multi-frequency sound, several valves can be controlled simultaneously and resultantly the pneumatic multi-degree wearable system can be constructed compactly. In this paper, firstly, the sound-gas pressure converter, which uses the resonance of a vibrating object consisting of a leaf spring and head, is proposed and is improved so that self-excited vibration does not arise. Secondly, the basic characteristic of the sound-gas pressure converter is investigated, and it is clarified that the back pressure is different depending on whether the sound of specific frequency exits or not. Furthermore, a pilot valve of the sound operated directional control valve is developed by combining the sound-gas pressure converter with a vibration transmitting element, which transmits the vibration in the tube to the sound-gas pressure converter. Using a Dry-Ice Power Cell developed in a previous study as the portable gas supply, the characteristic of the developed pilot valve is investigated experimentally. It is clarified that a definite change of back pressure of the pilot valve in response to the sound inside the gas supply tube can be obtained, and it is concluded that the developed valve can be used as a pilot valve of a sound operated directional control valve.

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