Moving body position control apparatus and signal reproducing apparatus

A moving body position control apparatus comprising:

• driving means for driving a moving body in response to a drive signal;
• position detecting means for detecting a position of the moving body and recurrently outputting a position detection signal representing the detected position of the moving body;
• receiving means for receiving a position command signal representing a desired position of the moving body;
• position error determining means for determining a difference between the position command signal and the position detection signal recurrently output from the position detecting means, and recurrently outputting a position error representing the determined difference between the position command signal and the position detection signal;
• position adjusting means having an adjustable gain for generating the drive signal for the driving means on the basis of the adjustable gain and the position error recurrently output from the position error determining means so as to reduce the position error substantially to zero;
• position error value calculating means for recurrently calculating a position error value on the basis of a first plurality of position errors output from the position error determining means during a first predetermined period;
• and
• gain adjusting means for adjusting the adjustable gain of the position adjusting means on the basis of the position error value.