Abstract: A vehicle attitude control device including a yaw moment control mechanism for giving a yaw moment to the vehicle and controlling the yaw moment, and a controller for controlling the yaw moment control mechanism in a normal target follow-up control mode so that the actual yaw rate detected by a yaw rate sensor coincides with a target value determined on the basis of an angle of rotation of a steering wheel detected by a steering wheel angle sensor, and wherein a yaw moment reducing device is provided for reducing the yaw moment to be given to the vehicle by the yaw moment control mechanism, to a reduced value smaller than a normal value to which the yaw moment is controlled in the normal target follow-up control mode.

Abstract: An estimation method of estimating a lateral slip angle and a yaw rate or a wheeled vehicle on a basis of a state equation of an observer to be applied with a real yaw rate as a reference input, the observer being designed on a basis of a turning movement model which defines a steer-angle of the vehicle as an input variable and defines the lateral slip angle and the yaw rate as a state variable, wherein a forward speed, a steer-angle, a yaw rate and a lateral acceleration of the vehicle are detected to estimate a lateral acceleration based on the lateral slip angle and yaw rate calculated on a basis of the state equation of the observer and the detected forward speed, a correction coefficient is calculated on a basis of a ratio of the detected lateral acceleration and the estimated lateral acceleration, and a factor of a cornering power defined in the state equation of the observer is multiplied by the calculated correction coefficient.

Abstract: A vehicle state observer system includes a state quantity measuring unit which measures an observable quantity of state of a vehicle. A controlled variable detecting unit detects a controlled variable of the vehicle. An observer estimates an unobservable quantity of state of the vehicle from the observable quantity measured by the state quantity measuring unit and the controlled variable detected by the controlled variable detecting unit, in accordance with a system matrix including a system variable. A system variable detecting unit detects the system variable included in the system matrix. A correcting unit corrects a pole of the observer in response to the system variable detected by the system variable detecting unit.