BMW 7 Series: Functional Principal

Lane Departure Warning

The lane departure warning causes the steering wheel to vibrate to warn the driver that the vehicle is threatening to leave the current lane without driver intending it to do so. The prerequisite for this function to work is the presence of road or lane markings that can be recognized by the control unit based on an evaluation of the images recorded by the forward facing video camera.

The system is therefore intended to assist the driver in case of a lapse of attention. Nevertheless, the driver continues to bear full responsibility for the vehicle.

The system is designed to assist the driver on highways, major roads and well maintained country roads.

Warnings are given, therefore, only at speeds of over 44 mph.

The driver activates the system using the lane departure warning button in the BEFAS driver assistance control panel.

Fig. 107: Identifying Lane Departure Warning

Fig. 108: Display Lane Departure Warning Button On BEFAS Control

The "system ON" state is indicated in the instrument cluster and, where applicable, in the head-up display by the following symbol.

Fig. 109: Display Lane Departure Warning Switched On

The activated system is ready as soon as lane markings are detected by the control unit and the vehicle is travelling faster than 44 mph.

The ready state of the system is represented by additional arrow symbols in the display.

Fig. 110: Display Lane Departure Warning Ready

If the vehicle threatens to drive over a lane marking and leave the lane without the driver intending it to do so, the driver is alerted by a vibrating of the steering wheel.

The lane departure warning senses an intentional change of lane made by the driver from the activation of the turn signal. In this case there is no warning when the vehicle is driven over the lane marking.

Fig. 111: Identifying Steering Wheel And Vibration For Lane Departure Warning On F01/F02

STEERING WHEEL LEGENDS

1. Steering wheel electronics
2. Vibration actuator for the lane departure warning

STEERING COLUMN LEGENDS

1. Turn signal/high-beam stalk on the steering column in the F01/F02
2. Turn signal

Fig. 112: Identifying Turn Signal And High Beam Stalk On Steering Column

Lane Detection

Fig. 113: F01/F02 Lane Departure Warning Video Camera

The lane departure warning video camera integrated into the base of the rear-view mirror on the windshield monitors the area ahead of the vehicle. The video camera captures the roadway up to approximately 131ft. to the front of the vehicle and up to approximately 5m/16.4 ft to the right and left.

The image data is sent to the KAFAS control unit along an LVDS data line for analysis. Using image processing technology, the control unit scans the images recorded by the video camera for lane and roadway markings.

The software in the control unit also checks which lane markings apply to the current lane in which the vehicle is driving.

First, the control unit calculates the vehicle's position relative to the lanes detected in the camera images and then uses this position as basis for converting the data into a lane departure warning.

The fundamental parameters for this calculation are the road speed and steering angle of the vehicle.

Roadway Marking

The roadway markings in the image may differ greatly depending on the country, type of road or prevailing environmental conditions. The system is capable of recognizing a wide range of roadway markings and types of marking.

A lane marking is subject to unequivocal recognition by the video camera and control unit first. The lane traveled must have an average width of at least 2.5m.

Physical Limitations of the Optical System

The lane departure warning functions under a wide range of different environmental conditions.

Due to the physical limitations of the system, system availability may be affected by specific road and environmental conditions, such as snow, fog, rain, or glare and dazzle.

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