BMW 5 Series: Steering interventions

If the current course of the vehicle deviates too much from the target trajectory (path curve), a steering correction is initiated.

The steering intervention is a corrective measure. This means the driver is not relieved of his duty to steer the vehicle. As the corrective steering interventions are limited to approximately 1.5 m/s² based on the lateral acceleration, the system cannot navigate curves above the respective speed-dependent curve radius without the driver's assistance. The driver must therefore steer the vehicle at the same time in order to stay on the roadway.

The target trajectory and required steering corrections are calculated based on the driving speed as follows:

Speed range 0 to 43 mph (0 to 70 km/h):

• The position and previous movements of the vehicle driving ahead are given priority when determining the appropriate steering corrections.
• Detected lane markings are taken into account to avoid unwanted steering corrections that would result in leaving the lane.
• Corrective steering interventions in the direction of the center of the lane are initiated if the vehicle detects there is not a vehicle driving ahead.

Speed range 43 to 80 mph (70 km/h to 130 km/h):

• Corrective steering interventions in the direction of the center of the lane are initiated.
• It is possible to bridge the gap for a limited time where lane markings are not detected by estimating the course of the lane based on the vehicle driving ahead.

Speed range 80 to 130 mph (130 km/h to 210 km/h):

• Corrective steering interventions in the direction of the center of the lane are initiated.
• For safety reasons above a driving speed of approximately 80 mph (130 km/h) the course of the lane is not estimated using the vehicle driving ahead.

The vehicle driving ahead is given priority as the "correction target" at speeds up to approximately 43 mph (70 km/h) due to the limited detection of lane markings.

In traffic jams or slow-moving traffic following distances are often extremely small (< 30 ft (< 10 m)) due to tailgating and lanes ahead are often partially covered due to staggered driving.

This means the KAFAS stereo camera is unable to correctly interpret the lane markings in some cases.

When classifying the object driving ahead, vehicles such as motorbikes are not used as the "correction target".

Steering momentum

The driving dynamics function software in the Dynamic Stability Control (DSC) control unit calculates a target steering torque based on the curve nominal value. The target steering torque is then converted to an engine torque by the Electronic Power Steering (EPS), which finally results in a steering wheel movement at the wheels.

The maximum steering torque has been set in such a way that it can always be overruled by the driver and therefore steering past the maximum steering torque is possible.

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