To prevent the controllability of a servo valve from lowering owing to the nonlinear characteristics.
An actuator comprises: a hollow cylinder; a piston stored in the cylinder, and moving relatively to the cylinder while forming a pair of pressure chambers together with the cylinder; a pair of control valves for making each of a pair of the pressure chambers communicate or shut off relative to pressure source of working fluid or a discharge section; a position detector for detecting the position of the piston with respect to the cylinder; an exhaust valve for discharging the working fluid from at least one of a pair of pressure chambers; and a control section for controlling the control valves so that the position detected by the position detector approaches a predetermined target position.
SANADA SATORU
NAKAHIRA NORIO
Kazutoshi Iiyama
Akashi Hideya
Shigenori Hayashi