空気圧サーボ系の制御性能評価とその特徴

抄録

To improve the performance of pneumatic actuation, the relation between the inherent low stiffness characteristic due to the air compressibility and its controllability has to be grasped. Also, the application forms which can make use this characteristic have to be considered.
In this study, the inherent stiffness of a pneumatic cylinder, fundamental control performance and mechanical impedance of a pneumatic servo using a cylinder are analyzed theoretically and experimentally. The results can be summarized as follows.
1) The inherent stiffness of a cylinder can give the fairly significant criteria for estimating the control accuracy of the pneumatic servo. The higher the stiffness becomes, the higher the accuracy of position and force controls become.
2) One of the features of the pneumatic servo is its relatively low impedance in the low frequency range and its increase in the not so high frequency range owing to the relatively low natural frequency of the pneumatic servo system.
3) From the above features, it may be considered that a pneumatic servo is effective for both the position control disturbed by relatively high-frequency load force variations and the force control being subjected to low-frequency displacement variations.
Lastly, typical features of a pressure feedback compensation considered to be useful for a pneumatic servo are investigated.