Vehicle state estimation device

A vehicle state estimation device which is applied to a vehicle having four wheels, including front left and right wheels and rear left and right wheels, and a sprung including a portion of the vehicle body from which the wheels are suspended by suspensions that can expand and contract at least vertically, comprising:

• wheel speed detection devices that detect wheel speeds of the four wheels;
• and
• an electronic control unit (ECU) configured to:
• calculate state quantities of at least the sprung on the basis of detected wheel speeds of the four wheels;
• calculate an in-phase component of wheel speeds of left and right wheels and a reverse phase component of wheel speeds of left and right wheels for the front and rear wheels;
• calculate a pitch angular speed of the sprung and a yaw angular speed of the sprung on the basis of the in-phase component of wheel speeds of left and right wheels and the reverse phase component of wheel speeds of left and right wheels, respectively;
• and
• based on the calculated in-phase component, control an actuator of at least one shock absorber of the vehicle in order to control the damping force of the at least one shock absorber.