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Optimal Steering in Critical Situations

Bosch is Developing a Steering Assistant for Cars 

July 6, 2004

If there is a risk of a car skidding, quick and accurate steering is required in order to keep the car safely on course. Bosch is currently developing an assistance function that will help the driver to steer optimally during critical situations. The system increases or reduces the support of the power steering. This makes it easier for the driver to execute the steering maneuver according to the situation. 

In co-operation with a car manufacturer, Bosch is currently developing such a system for series production; testing with prototypes is being carried out.

The steering assistant is particularly interesting as all that is needed to realize it, is additional software. The vehicle must merely be equipped with an electronic stability program (ESP) and electric power steering. 

By means of the ESP sensor data on the driving stability of the car, the steering assistant recognizes critical driving situations and determines optimal steering. If the steering of the driver does not agree with the determined values, the power steering support is increased or reduced. The altered steering-wheel torque now causes the driver to adjust his own chosen steering angle to the optimal steering angle for the driving situation. Quicker and more precise steering movements are the result and the car remains more safely on the desired course of the driver. The ESP must only intervene via the brakes in particularly critical situations.

If there is a risk of the vehicle, for example, oversteering, the driver must rapidly countersteer in order to avoid the vehicle skidding. In this connection, frequent mistakes of inexperienced drivers are countersteering too late, too little and then countersteering for too long. In the case of understeering the driver often steers too sharply, which further reduces the lateral forces of the tires. The steering assistant supports the driver in both cases, allowing him to mitigate the situation through a precise steering maneuver. The function during full braking on a lane which is slippery on one side is also an advantage. For even with the ABS function, the driver must hold the vehicle steady by lightly countersteering. Here too, the steering assistant helps the driver to maintain ideal steering.

To ensure that the driver also accepts the assistant function, the definition of the system parameters is a very important point. The steering assistant is so designed that it supports but does not impose. The majority of drivers that have already tested the system have thus come to the same conclusion: When the function is activated, critical situations can be more safely and simply overcome. In this way, the steering assistant extends the stabilizing effect of the ESP. Safety in road traffic is thus further increased.

Source: Bosch PI4563 - July 2004