We attempted to play the xylophone automatically by controlling pneumatic components. A bar was controlled by proportional pressure control valves and high cycle solenoid valves. The width of the bar was about 25mm, the range of positioning the bar was from-12.5mm to +12.5mm of the desired positions. The positioning accuracy of striking bars was not restricted within narrow limits, but high velocity positioning is required t o play the xylophone automatically. We controlled position of the bar by pole assignment control to realize fast positioning. To achieve fast positioning of the bar, compressed air a port on the left or right was expelled. When the error is greater than 55mm, the left port is opened, and when the error is less than-55mm, the right port is opened.

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Energy conservation for pneumatic systems is very important because energy conservation in industry is a world-wide problem related to protection of the environment. In this paper, we have researched energy conservation for pneumatic systems. Practically, features of pneumatic drive systems are clarified from the viewpoint of protection of the global environment, and reduction in air consumption is most effective for conserving energy in pneumatic equipment.
In addition we propose a method to achieve reduction in air consumption for the pneumatic cylinder system operated by PTP driving, and examined methods realizing practical applications for various pneumatic systems.

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This paper deals with the improvement of OHC-Sim which is a simulation package for the design of an oil-hydraulic circuit and analysis of its dynamic characteristics. To make the design and improvement processes of an oil-hydraulic circuit more effective and systematic, OHC-Sim was developed with the support of JHPS (the Japan Hydraulics and Pneumatics Society). It has been improved and enhanced in the research committee of JHPS. It includes a user friendly graphical user interface in Windows 95® environment, and provides easy design and improvement of an oil-hydraulic circuit on the basis of simulated dynamic behavior by a personal computer. In this paper, the structure of the oil-hydraulic component icon and how to connect component icons in OHC-Sim are emphasized, and have been improved to make OHC-Sim more useful. In addition, through examples, the main features of OHC-Sim are shown.

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Pneumatic cylinders may not achieve steady motion when driven at low speed because of the stick-slip effect. However, an effective means to assess the possibility of stick-slip occurrence in pneumatic cylinders has not been presented. Therefore, it is still unknown under what conditions stick-slip occurs. In the first report, it is shown that stick-slip can be described with good accuracy by simulation. However, there are many parameters in the simulation of stick-slip, that it is not easy to clarify the occurrence conditions of stick-slip and the influence of each of the parameters.
Therefore, in this report, the occurrence conditions of stick-slip are studied analytically using dimensionless parameters. It is found that the occurrence conditions of stick-slip in pneumatic cylinders can be expressed in function of two dimensionless parameters. The analysis is validated through experiments shown in the first report. The influence of each parameter on the occurrence of stick-slip is clarified.

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