Abstract
Presently, the automotive industry is on the threshold to an era of revolutionary developments in the steering-technology sector. For many years, modern power-steering systems have been dominated by hydraulic systems. These systems have achieved an outstanding level of efficiency, comfort, variability and economy; but now a dramatic upheaval is becoming apparent. A large number of European and Asian vehicle manufacturers are switching over to electronically assisted power-steering systems as they promise advantages with regard to fuel consumption and logistics. These systems will soon conquer the markets. However, approaches known under the keyword "steer-by-wire" promise even more radical changes: here, omission of the conventional steering column constitutes an outstanding challenge with regard to safe practice and design.
Motivating factors for the use of such electronically controlled steering systems: the increase in passive personal safety; the chance to improve active safety by means of electronic steering intervention in cooperation with driving mode sensors; the high degree of constructive freedom concerning the arrangement and designing of the engine compartment components; easier assembly; and a high degree of flexibility of steering parameters, such as the steering ratio, due to software functions.
Also conceivable: external steering control, e.g. by means of the traffic guidance systems of the future.
Characteristic features of such electronically controlled steer-by-wire systems: separation of the connection between steering wheel and axle; an interface of the steering system for internal and external steering commands; and monitoring of the steering commands as to their compatibility with the respective driving mode.
Core element of this split steering system: functional separation between the drivers sense of steering (analogous to the sense of orientation) including driving-mode feedback for the driver on the one hand, and active control of steering activation on the wheels on the other hand.
At the moment, there are still legal restrictions for such systems, and legislation will only be amended in the wake of the development of safe and reliable overall concepts and systems. Any safety concept must consider and adopt standards as they exist, for example, in aviation (fail-safe etc.).