| 摘要 |
A magnetic disk apparatus includes a following compensator for measuring a frequency characteristic of an under-control object to stabilize a vibration mode of the under-control object with phase condition and a resonance filter having a resonance point in the vicinity of a frequency at which positioning accuracy is to be enhanced, being coupled in parallel to the under-control object. Polarity of mode constant of the resonance filter is so determined as to stabilize a vibration mode brought about by the resonance filter on the basis of a relation between the frequency stabilized by a control system and the phase-180� crossover frequency. Positioning accuracy at a specific frequency can be enhanced without involving unstability in the control system even in a frequency range where sensitivity function of the control system is higher than 0 dB inclusive. |
