In this research, we propose to install a guidance structure to an element with radial flow between two parallel disks named a radial slit, and investigate its influence on the noise characteristics experimentally. Even if the radial slit is applied to pneumatic components with casing cover, the guide structure is expected to preserve advantage of silence ability. The noise characteristics of the radial slit without the guidance structure and with the guidance structure, which has a sudden-expansion of flow area, are compared experimentally. It is observed that high frequency noise is generated and the silencing ability of the radial slit gets worse by installing the guidance structure. In order to obtain the angle of the guidance structure for minimizing the noise level, the angle varies from 3 degrees to 60 degrees and these noise characteristics are measured under the same differential pressure. As a consequence, it is found that the noise level has a minimum value when the angle of the guidance structure is in the range from 10 degrees to 20 degrees. The flow pattern on the surface of the guidance structure is visualized by the oil film technique. The observed flow patterns change with increasing the angle, and the features of these flow patterns are described as follows; (i) when the degree of the guidance angle is small, a triangular shaped sediment accumulation of an oil film is observed on the surface of the guidance structure, (ii) the flow in the radially inward direction occurs on the surface with increasing the angle, and (iii) when the angle is more than 30 degrees, the flow begins to separate from the surface of the guidance structure. By combining the results of the noise characteristics and visualization, it is found that the noise level is minimized during transition between (i) and (ii).

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The purpose of this study is to construct a robot that plays a soprano recorder with realistic sound. Recent years have seen the development of robots that entertain by playing a variety of musical instruments. There have been many reports describing the musical expression of such robots, for example, of robots with artificial lips for playing wind instruments. However, robots playing wind instruments often produce artificial sounds that differ considerably from those produced by their human counterparts, particularly when performing special musical effects, such as vibrato, tremolo, and tonguing.
To build a robot that produces natural soprano recorder sounds matching those produced by a human player, the following procedure was followed. First, the static and dynamic characteristics of the flow sensor measuring blown air were calibrated with an unsteady flow generator to judge whether the sensor’s performance was sufficiently accurate. Second, the blown air flow rates were measured when human players performed vibrato with a soprano recorder. Finally, the identified flow rate model was applied to the robot’s air flow rate control system. The flow rate was controlled by a spool type servo valve. The sounds produced by the human player and those produced by the robot player were compared using a sound analyzer. The experiment showed that the results obtained for the human player and for the robot agreed very well.

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This research discusses novel methods of enhancing the casting height of a tethered payload by efficiently using the casting motion generated by a pneumatic cylinder. Generally, the tether is stored into a case fixed near the actuator. The difference in casting heights depends on the method with which the tether is set. The authors propose two methods relying on applying kinetic energy to the tether along with the payload: the unified type and the discharge type. In addition, in order to generate high-speed motion in a light structure, the authors propose a novel cylinder termed the MB Cylinder. The selection of casting method is based on analysis of the velocity provided by this cylinder. In order to approximate to the ideal situation, a structure that mitigates friction between the tether and its storage case is also proposed. Experimental results show the efficiency of the proposed methods.

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