PURPOSE: To prevent control stability from being lowered by the mutual action of a motor and a driven load, to lower control loop noise sensitivity and to quicken a time response by coupling or reconstructing signals from the group of various kinds of sensor measure signals while utilizing a correction filter.

CONSTITUTION: A motor 12 is connected to a driven load 16, and that load is driven by the actuator of a rotary screw or the like. A controller 10 uses a pair of sensors for sensing or measuring the position of the motor 12 or the driven load 16. A sensor 18 monitors a motor rotation rate, measures the motor position and sends a position signal through a line 22 to a complementary filter 20. The linear transformer of an LVDT sensor 24 or the like is connected to the driven load 16, monitors the screw position of the driven load 16 and sends a 2nd position signal to the complementary filter 20. The complementary filter 20 couples or mixes two various kinds of sensor measured values and generates a scheduled position signal. This signal is exacter than the signal of a sensor 18 or 24 over all the frequency ranges.