| 摘要 |
PURPOSE:To improve stability in a closed system by using an LPF removing unnecessary high frequency noises and resonance points and a notch filter removing local resonance points to make respective resonance frequency coincide with each other. CONSTITUTION:An LPF removing unnecessary high frequency noises and a notch filter removing local resonance points are combined, and the generated frequency of a peak of gain at the LPF and the gain falling frequency of the notch filter, i.e. resonance frequency of the LPF and notch filter, are made to coincide with each other. The coincidence of resonance frequency prevents a gain margin in a closed loop system from falling and constitutes a stable closed system. In the frequency characteristics of composed gain between the LPF and the notch filter as shown in the figure, the generation of a peak value is prevented and gain margin is improved. Consequently such a closed loop can be improved in its stability in a magnetic disc unit using a closed loop positioning controlling system. |
