Patent ID: 6704160
Filing Date: 2004-03-09
Classification: G11B

Abstract:
A feedback control system for controlling a device comprising:a feedback control unit configured to sample a differential signal representing a difference between a desired value and an output provided by the device at a sampling frequency, and producing a control command value; a multigain unit configured to divide one sampling period into a combination of a plurality of time periods according to a predetermined time period dividing rule, and to allot gains in the plurality of time periods, respectively, according to a predetermined gain allotting rule; a multihold unit configured to hold products of the control command value and the gains allotted by the multigain unit as fixed values for the time periods, and to generate a control waveform; and a driving unit configured to apply the control waveform generated by the multihold unit to the device, wherein the predetermined time period dividing rule and the predetermined gain allotting rule firstly set a zero point in a transfer function associated with sampling and digitizing the differential signal at the sampling frequency, the zero point being different from a zero point when the gain is set at â€œ1â€  in the sampling period, and secondly lower the gain of the frequency characteristic of the multihold unit in a frequency band including a mechanical resonance point of the device.