Vibration control apparatus

A vibration control apparatus comprising:

• state detecting means for detecting a physical value influencing characteristics of a suspension for supporting a vibrating body and for detecting a state value representing movement of the suspension:
• control means comprising target control force calculating means for calculating an optimal target control force in consideration of an external force or disturbance acting on the suspension, on the basis of the physical and state values as outputs from said state detecting means, detection control force calculating means for calculating a detection control force corresponding to the physical value detected by said state detecting means, and deviation calculating means for detecting a deviation of the detection control force from the target control force;
• driving means for amplifying a deviation signal representing deviation of the detection control force from the target control force and generated by said deviation calculating means and for generating a power output signal based on the amplified deviation signal;
• and
• actuator means for continuously, variably controlling the suspension characteristics so as to equivalently generate a control force corresponding to the deviation of the detection control force from the target control force in consideration of the external force or disturbance acting on the suspension, on the basis of said power output signal;
• said target control force calculating means comprising;
• state frequency distribution calculating means for receiving as an external state signal, the input signal representing the state or physical value output from said state detecting means, for counting a frequency of passing, in units of preset levels, every time the input signal passes through the preset levels representing degrees of states of the input signal to calculate a frequency distribution of the preset levels every predetermined period of time, and for continuously discriminating an external state according to said calculated frequency distribution;
• gain selecting means for selecting optimal values of prestored gains on the basis of the frequency distribution from said state frequency distribution calculating means;
• and
• optimal target control force calculating means for multiplying the gains selected by said gain selecting means with the state or physical value signal output from said state detecting means and for adding the products obtained by the successive results of multiplying the gains with the state or physical value signal to obtain the optimal target control force,
• wherein the frequency distribution of the state or physical value is calculated by said state frequency distribution calculating means to accurately, continuously detect a change in the external state, the optimal target control force is calculated using the gains corresponding to the change in the external state, and an optimal target control force free from influence of a pulsed external force or disturbance component is generated, thereby continuously, optimally, variably controlling the suspension characteristics.