Patent ID: 7599774

Claim:
An active front wheel steering control system for a vehicle having steerable front wheels and fixed rear wheels, comprising: a vehicle steering wheel configured to generate a steering wheel angle signal corresponding to a steering wheel angle; a steering actuator configured to control the steerable front wheels based upon a steering control signal comprising a combination of an open-loop steering control signal and a closed-loop steering control signal; a real-time vehicle dynamics estimation subsystem configured to estimate vehicle dynamics parameters based upon signal inputs from vehicle sensors; an open-loop control subsystem configured to provide the open-loop steering control signal corresponding to the steering wheel angle signal; a closed-loop control subsystem configured to provide the closed-loop steering control signal based upon the estimated vehicle dynamics parameters; a yaw rate feedback look-up table configured to provide an original yaw rate feedback angle signal; and a yaw rate feedback adaptive compensation sub-system configured to provide a corrected yaw rate feedback angle signal based on the estimated vehicle dynamics parameters; wherein the yaw rate feedback adaptive compensation sub-system is configured to provide the corrected yaw rate feedback angle signal in accordance with the relationship: δ RP = K RP o ⁡ ( V x ) · ( Ω c - Ω ) + ( Δ ⁢ ⁢ K RP Δ ⁢ ⁢ T ⁢  o ⁢ ⁢ Δ ⁢ ⁢ T ⁡ ( V x ) + Δ ⁢ ⁢ K RP Δ ⁢ ⁢ D F  o ⁢ ⁢ Δ ⁢ ⁢ D F + Δ ⁢ ⁢ K RP Δ ⁢ ⁢ D R  o ⁢ ⁢ Δ ⁢ ⁢ D R ) · ( Ω c - Ω ) where, Ω is the yaw rate; Ω c is the yaw rate command; K 0 RP (V x ) is the nominal yaw rate feedback gain table as a function of vehicle speed; ΔD F is the change in the front cornering compliance; ΔD R is the change in the rear cornering compliance; ΔT is the deviation in the open-loop gain; and Δ ⁢ ⁢ K RP Δ ⁢ ⁢ T ⁢  o , Δ ⁢ ⁢ K RP Δ ⁢ ⁢ D F  o ; Δ ⁢ ⁢ K RP Δ ⁢ ⁢ D R  o is the yaw rate P-gain sensitivity to open-loop gain, front cornering compliance, and rear cornering compliance, respectively.