The steering system of the invention includes a processing means (26) comprising a means for determining (30) a driving signal (S3) of the power means (25) on the basis of: a first control signal (S1) determined from the measure of a torque applied by the driver on the steering wheel by applying a gain that depends on the longitudinal speed of the vehicle; a second correction signal (S2) determined from the measure of the torque applied by the driver on the steering wheel, and a setpoint determined on the basis of at least one characteristic parameter of the lateral dynamics of the vehicle.