PURPOSE: To speed up a positioning work by setting output signals from both a fluid power detecting unit and a working-state detecting unit as input data in order to estimate an external disturbance acting on a working part and obtaining a command value that is necessary to compensate the external disturbing force together with outputting the value to a control valve group.
CONSTITUTION: A disturbing force compensating part 15 takes in the signal from a position sensor 11 and from pressure sensors 12a and 12b and outputs a command value on the opening areas of control valves 10a and 10b, which are necessary to cancel the friction force acting on a piston 2, utilizing a friction-force-value estimated by an external disturbing force estimating part. Command value compensating parts 16a and 16b input a sum of command values from a control part 14 and from the compensating part 15 to the control parts 10a and 10b in order to compensate the command values, based on a prescribed, relational expression. By changing the opening area of the valve part, the control valves 10a and 10b change the rate of inflow/outflow to/from pneumatic chambers 1a and 1b, thereby controlling both the pressures in the pneumatic chambers 1a and 1b and the position of a load 6. With this contrivance, quick and precise control can be achieved.
MATSUBAYASHI SHIGEAKI
MATSUURA SADAHIRO
