Abstract: A control system for a controlled vehicle has a steering wheel angle sensor, a vehicle speed sensor, a turning behavior sensor such as a side speed sensor and a yaw rate sensor, an actuator such as a hydraulic system for altering a rear wheel steer angle in accordance with a desired angle value, and a controller such as a microcomputer for determining the desired angle value by solving three distinct vehicle models. The controller first solves a reference model representing a desired vehicle to determine a desired vehicle response to the steering wheel angle and vehicle speed, and then solves a first actual model representing the actual controlled vehicle to determine the desired rear wheel steer angle value required to cause the controlled vehicle to produce the desired response.

Abstract: A vehicle steering control system has a steering wheel angle sensor, a vehicle speed sensor, a control unit and an actuator for steering either (or both) of front and rear wheel pairs of a controlled vehicle. The control unit determines desired values of yaw rate and lateral acceleration corresponding to the sensed steering wheel angle and vehicle speed by using at least one desired mathematical vehicle model having desired vehicle response characteristics. Then, the control unit determines a desired value of a front or rear wheel steer angle (or both of the front and rear wheel angles) theoretically required to achieve the desired value of the yaw rate, and another desired value of the steer angle theoretically required to achieve the desired value of the lateral acceleration. Finally, the control unit determines a weighted average of two desired values of the steer angle by using weights which are functions of vehicle speed and/or steering wheel angular speed.

Abstract: A control system for steering front wheels and rear wheels of a controlled vehicle has a processing unit such as a microcomputer which determines a desired value of at least one of dynamical variables such as yaw rate, yaw acceleration, and lateral acceleration from sensed steering input and sensed vehicle speed by solving equations of motion of a vehicle in which parameters inherent to the vehicle are set equal to desired values so determined as to provide desired cornering characteristics. From the desired value of the dynamical variable, the processing unit determines desired values of front and rear steering angles of the front and rear wheels required to achieve the desired value of the dynamical variable in the controlled vehicle.