PURPOSE: A dual-stage servo system using feed-forward study control input is provided to makes design easily and improve control performance by using feed-forward study control input. CONSTITUTION: A first actuator device(30) records data on a recording media or changes a head position to reproduce recoded data. A second actuator device(31) changes a displacement relative with the first actuator device(30) and controls a head position finely. An error detection device detects the difference between a basis position of the recording media and a real position of the head. A first control part(33) outputs signal to drive and control the first actuator device(30) using output of the error detection device. A second control part(34) outputs signal to drive and control the second actuator device(31) according to output of the error detection device. A third control part(35) reads a predetermined control input to drive the first actuator(30) and adds this to the first actuator device(30) together with output of the first control device(33).
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