AUTOMATIC CAR STEERING CONTROL BRIDGES OVER THE DRIVER REACTION-TIME

A car driver needs at least five hundred milliseconds before he carl r eact to unexpected yaw motions. During this time the uncontrolled car may produce a dangerous yaw rate and sideslip angle. Automatic steerin g control for disturbance rejection is designed such that it bridges o ver the driver reaction time, but returns the full steering authority to the driver thereafter. The solution is robust with respect to uncer tainties in the road-tire contact and in the mass and velocity of the vehicle. The yaw disturbance transfer function is compared with those of the ideally decoupled car and of the uncontrolled car. The frequenc y responses are evaluated in the form of disturbance attenuation ratio s and frequency limits.