| In conventional steering systems there is a direct mechanical connection between the steering wheel and the steering gear. This establishes a fixed ratio between the steering wheel lock angle and the turn angle of the steered wheels. In this design, only one transmission ratio can be implemented on a vehicle at a time. Selecting the appropriate transmission ratio always represents a compromise in meeting the different - and sometimes conflicting - requirements. The key requirements can only be optimally met by a variable transmission ratio. A transmission ratio of this kind varies the actual turn angle of the wheels depending on the vehicle speed and steering angle. The dynamic steering system generally implements two variable transmission ratios, with comfort and performance-oriented characteristics respectively. The variable transmission ratios are implemented by means of an additional electro-mechanical drive of the steering pinion, which is superimposed on the steering input from the driver. In an emergency - that is, if this drive fails - the steering operates just like a conventional steering system. The mechanical connection between the steering wheel and the front axle is not broken. However, there are many other advantages to dynamic steering. In interaction with the ESP and its sensors, the system is also activated when critical driving states are impending. By targeted variation of the front wheel turn angle, the dynamic steering system assists the ESP at the limits of the vehicle's handling. |
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