Development of Pneumatic Servo Table for Accurate and Speedy Positioning Mounted with Externally Pressurized Air Bearings.

In pneumatically actuated servo mechanisms, accurate and speedy positioning as an electric servo has been regarded as being difficult because of the disturbance caused by fluctuations in the friction force and air compressibility been carried out. Therefore, studies on positioning in a pneumatic servo have concentrated regarding the compensation of nonlinearity according to air compressibility and friction force. In this study, an servo table mounted with externally pressurized air bearings is proposed to compensate for the friction force that has a serious effect on the accurate positioning in the vicinity of the reference dis-placement. The table is driven by two servo valves operating at nearly 100Hz for speedy positioning. As a result, this study was able to confirm that the friction force on this table was nearly zero, therefore, 10μm accuracy could be obtained easily by using this table at positioning and in the case of Ref. 2mm, the table was converged to it in 16ms within an accuracy of ±10μm.