Patent ID: 8494717

Claim:
An electric assisted steering control strategy for a steering system for a vehicle which is arranged to assist the driver in controlling the vehicle during a split mu braking operation, the control strategy comprising: basing the assistance on at least one operational variable representing a corrective steer angle for the vehicle which is added to a main assistance torque via a driver feedback controller, and in which the strategy employs an estimate of yaw moment of the vehicle as the operational variable, the estimate of yaw moment of the vehicle being determined by processing the speed of wheels on opposite sides of the vehicle, wherein the determination of the estimate of yaw moment of the vehicle includes the steps of: (a) obtaining a first estimate of the speed of a front left wheel and a second estimate of the speed of a front right wheel of said vehicle; (b) determining the difference between the first estimated speed and second estimated speed; (c) multiplying the difference by a constant to give the difference in wheel speed for the front wheels; and (d) dividing the result by the track width of the vehicle.