デジタル空気圧シリンダシステムに関する研究

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抄録

Positioning using a pneumatic system is much more difficult compared with that by a hydraulic system for different compressibilities of the working fluids, but for some working conditions, pneumatic systems are more suitable due to their clearness and safety.
To position reliably and accurately without any load, a pneumatic system, in which several cylinders are connected to each other in series and the actions of the cylinders are controlled by a microcomputer, can be used. Especially when the the stroke of each cylinder in some unit varies in a 2^n-1 sequence where n is the integer number beginning from 1, the total displacement of the cylinder series can be any integer in this unit from 0 to 2^N-1 where N is the number of the cylinders used in the system. Such systems have no feedback control and no electrical devices around the actuators, so that extremely high reliabilities and repeatabilities can be expected even when the systems are used under hazardous conditions such as around explosive gases or in a strong magnetic field.
In this research, the basic equations for such systems have been deduced. The experiments and simulations have been carried out by means of a model system without any external load in which four cylinders with strokes of 1cm, 2cm, 4cm, and 8cm were used. This paper reports on the following results obtained from the experiments and the computer simulation. That is, such a system is reliable for digital positionings, and the positioning paths as the outputs of the system can be made smooth by only adjusting suitably the timing according to which the driving signals for the actions of each cylinder are sent from a microcomputer.