空気圧サーボ機構の機械インピーダンス特性の応用

空気式スライドテーブルによる搬送・挿入作業の実現

抄録

A pneumatic actuator is not easily applied for accurate positioning tasks due to the compliance characteristic resulting from air compressibility. However, a pneumatic servo system can be considered as a kind of elastic type of body exposed to an external force owing to air compressibility even when positioning control is used. These characteristics have been applied to the conveying-peg-hole insertion tasks. Concretely, a peg is moved above a hole horizontally (not necessary to be accurate) by a long stroke pneumatic cylinder and the peg is inserted vertically to the hole by another pneumatic cylinder. Assuming that either the peg or the hole is chamfered, elastic displacement by a collision reaction force from a chamfering plane can be utilized as an absorption function of a relative positioning error, which allows for the insertion to be made. The possibility of insertion depends on the elastic characteristics (mechanical impedance) of positioning control system set up at the conveying cylinder and such a mechanical impedance is regulated by the pressure response characteristics. Since the position control system used here is based on pressure control, the desired impedance characteristics which are derived to provide for insertion analytically can be adjusted using pressure control. The validity of the proposed method could be confirmed through the carrying out of experiments.