ADDITIONAL 4WS AND DRIVER INTERACTION

This investigation is based on a complex 4-wheel vehicle model of a pa ssenger car that includes steering system and drive train. The tyre pr operties are described for all possible combined longitudinal and late ral slip values and for arbitrary friction conditions. The active part is an additional steering system of all 4 wheels, additionally to the driver's steering wheel angle input. Three control levels are used fo r the driver model that thereby can follow a given trajectory or avoid an obstacle. The feedback control of the additional 4 wheel steering is based on an observer which can also have adaptive characteristics. Moreover a virtual vehicle model in a feedforward scheme can provide d esired steering characteristics. To get information for critical situa tions a cornering manoeuvre with sudden mu-split conditions is simulat ed. Further a similar manoeuvre is used to evaluate the reentry in a h igh friction area from low friction conditions. And finally the perfor mance of the controller is shown in a severe lane change manoeuvre.