Patent ID: 7912606

Claim:
A steering control system for a land vehicle comprising: at least four steered wheels; one actuator per steered wheel; an actual steering angle sensor for each of the steered wheels; a control member available to a driver configured to deliver a demanded steering angle, a steering control unit which, by way of input variable, uses at least the demanded steering angle to determine a steering control angle for operating the said actuator; and a lock-up detector for detecting a lock-up of one of the steered-wheel actuators, said detector being capable, should a lock-up be detected, of delivering an alarm signal identifying which actuator has locked up, wherein said steering control unit includes at least one normal mode and at least one degraded mode in the event of an actuator becoming locked up, the degraded mode calculating the steering control angle of the non-locked wheels by imposing a first degraded-mode strategy whereby the instantaneous center of rotation (CIR) of the vehicle lies more or less on the straight line perpendicular to the plane of the locked wheel and passing through the center of the ground-contact area of the locked wheel, in a position that is dependent on the demanded steering angle.