Patent ID: 7137673

Claim:
A yaw stability system for a vehicle having a plurality of wheels each with a torque control element said yaw stability system comprising: a yaw rate sensor measuring a vehicle yaw rate; a plurality of braking devices each operably associated with one of the torque control elements and configured to exert a braking torque on the control element in response to a control command, wherein said braking devices are eddy current machines and wherein said control command is a current command; and a control unit communicating with said yaw rate sensor and configured to: identify a desired yaw rate, determine a yaw rate tracking error based on the difference between the desired yaw rate and the vehicle yaw rate, determine a yaw condition of the vehicle based on the vehicle yaw rate, determine a control yaw moment to minimize the yaw rate tracking error, select one or more of said plurality of braking devices based on the yaw condition, and communicate a control command to the one or more selected braking devices to induce said control yaw moment, wherein the control unit estimates braking device saturation torque (T est ) based on a quadratic function of rotor speed and excitation current.