汽车工程学Automotive Engineering-Steering.doc

2 Lateral Dynamics ( Driving Stability) 2 Lateral Dynamics ( Driving Stability)  PAGE \* MERGEFORMAT 186  PAGE \* MERGEFORMAT 187 2.5 Steering In the control loop consisting of the driver and the vehicle, the steering wheel angle forms a control variable, which has to be given by the driver in such a way that a deviation from the desired course remains small. However, there does not exist any distinct functional relation between the steering wheel turn executed by the driver and the change of direction necessary for a correction of course. The reasons for this are, for example, the elasticities in the steering system components and the occuring lateral accelerations. The relation between steering actuation and change of driving direction is represented in Fig. 2. 5-1. Fig.2.5-1 Relation between steering actuation and change of driving direction In order to drive a vehicle, the driver must constantly analyze the relation between steering wheel turn and change of driving direction. Apart from the optical information (deviation from the desired course), he receives a lot of further information, including for example lateral acceleration transmitted by the seat and steering torque passed on by the steering wheel. The function of the steering system is not only to transfer the steering wheel angle by a distinct allocation into a wheel steering angle but also to transmit information about the status of the vehicle movement to the driver. In the previous paragraphs (Chapter 2. 2-2. 4), the part of the control system between wheel angle modification and change of driving direction was dealt with. Now, the requested features of the structural component which defines the relation between steering wheel angle and the steering angle of the wheels are treated. Specifications of steering systems Since humans are integrated into the overall system driver-vehicle by the steering, the demands on this component are defined by the characteristics of humans and those of the vehic