Slip state detection apparatus and suspension control apparatus

A suspension control apparatus comprising:

• a longitudinal acceleration detection portion configured to detect a longitudinal acceleration of a vehicle and output a longitudinal acceleration signal;
• a wheel rotational velocity detection portion configured to detect a rotational velocity of each wheel and output a rotational velocity signal of the each wheel;
• a control device configured to input the longitudinal acceleration signal and the rotational velocity signal of the each wheel, determine a tire characteristic-considered slip ratio based on the input longitudinal acceleration signal and a tire characteristic, determine a corrected slip ratio of the each wheel by correcting the tire characteristic-considered slip ratio according to the rotational velocity signal of the each wheel, estimate a vertical motion of a vehicle body based on the rotational velocity signal of the each wheel, correct the estimated vertical motion of the vehicle body based on the corrected slip ratio of the each wheel, and output a control signal based on the corrected vertical motion of the vehicle body;
• and
• an actuator provided between the vehicle body and a wheel-side member and configured to change a state of the vehicle body in reaction to an input from the wheel-side member according to the control signal.