CROSSWIND FEEDFORWARD CONTROL - A MEASURE TO IMPROVE VEHICLE CROSSWIND BEHAVIOR

The theory of crosswind feedforward control was explained using the ex ample of a vehicle with active front-wheel steering. Beforehand, the c alculation formulas and frequency responses of the transient crosswind force and of the wind yaw moment acting on the vehicle were derived u sing the example of a simple vehicle fluid model. The influence of the transiency of crosswind disturbance on the dynamic crosswind behavior of a vehicle was then presented. The results of simulation confirmed the analyses carried out in the frequency domain for feedforward contr ol with front, rear and all-wheel steering. With front-wheel steering, the influence of crosswind on one of the vehicle movement variables ( lateral acceleration or yaw rate) could be almost completely compensat ed by dynamic feedforward control. With rear-wheel steering, it is onl y possible to compensate directly for the influence on the yawing rate . Due to the setting of the side force in the same direction as the la teral wind force at the start, active rear-wheel steering is not so su ccessful as active front-wheel steering. Nevertheless, the crosswind b ehavior of a vehicle can be considerably enhanced by feedforward contr ol with rear-wheel steering. The best crosswind behavior was obtained with active all-wheel steering: the vehicle hardly responds at all to crosswinds and remains on course despite heavy gusts of wind.