GF54.71-P-0002CA Automatic Lane Recognition, Function

GF54.71-P-0002CA Automatic Lane Recognition, Function
MODEL 207
- with CODE (476) Automatic lane recognition

Function requirements, general
^ Circuit 15 ON
^ Function in instrument cluster (A1) enabled
^ Vehicle speed: Warning at v = 60 to 250 km/h
^ Recognizable lane markings present on both sides (no construction site markings (yellow/white), no snow, not covered up, i.e. contrast too low)
^ Radius of curve r >150 m
^ Track width s = 2.5 up to 4.6 m
The electronic ignition lock control unit (N73) transmits the circuit status of circuit 15 via chassis CAN (CAN E) to the multifunction camera (A40/11).

Automatic lane recognition, general
The automatic lane recognition function detects any unintentional driving across lane markings and issues a haptic warning to the driver in certain circumstances through initiating vibrations on the steering wheel.
Crossing over lane markings is optically recorded and processed by the multifunction camera.
The haptic warning is generated by the steering wheel vibration motor (M99).
The automatic lane recognition function takes the driver's behavior into consideration and decides the point at which a warning is to be issued.
Under the following conditions any driving over lane markings is detected, but a warning is not issued:
- Turn signals
- Driver activities through evaluation of steering wheel movements, brake requests and accelerator pedal position
- Sporty cornering (corner cutting)
- Active control interventions by braking assistance systems





Illustration of the principle of automatic lane recognition
a Vehicle in the lane.
b Vehicle crosses over outer lane marking because driver distracted. Driver is then warned by means of steering-wheel vibration.
c The vehicle is steered by the driver back into the lane

The automatic lane recognition function operates on a speed- dependent basis and therefore requires the vehicle speed to be calculated as per the wheel speeds.
The wheel speeds are recorded by the following components:
- Left front axle rpm sensor (L6/1)
- Right front axle rpm sensor (L6/2)
- Left rear axle rpm sensor (L6/3)
- Right rear axle rpm sensor (L6/4)
The Electronic Stability Program control unit (N30/4) reads in the signals from the rpm sensors directly and sends them over the chassis CAN to the instrument cluster. The instrument cluster calculates the vehicle speed to be displayed and sends this over the chassis CAN to the multifunction camera.
The automatic lane recognition function includes the following subfunctions:
^ Function sequence for lane recognition
^ Function sequence for recognition of driver activity
^ Function sequence for recognition of control interventions
^ Function sequence for issuing warning

Function sequence for lane recognition
The multifunction camera, which is mounted at the top center on the front window, visually records the road space in front of the vehicle. To this end, the multifunction camera uses a fixed scan rate to document images of the lane and then sends them to the control unit integrated into the multifunction camera. The multifunction camera measures the lane based on the lane markings.





Schematic of lane recognition by multifunction camera

From the documented picture sequences and measurement values, that come from the lane marking pictures, a corresponding algorithm is used in the multifunction camera to calculate a lane.
The multifunction camera uses this data to calculate the relative position of the vehicle in the lane.
All the measures in the Automatic Lane Recognition function are derived from this position.
No lane information can be issued where there are no lane markings or if they are covered up (e.g. by dirt or snow) or where there is a low contrast between the road surface and lane marking or where there is a high level of glare.
For multiple markings on the traffic lane, the inner marking is always taken as the reference point.
When in construction site areas, the function is unable to issue warnings because of possible multiple lane markings.
The instrument cluster continuously displays the current status, in particular the warning readiness.





Possible displays:
- Function status
- Symbol off: Automatic Lane Recognition deactivated
- Symbol yellow (1): Automatic Lane Recognition activated, but not ready to issue warnings (e.g. v < 60 km/h)
- Warning readiness
- Symbol green (2): Automatic Lane Recognition activated and ready to issue warnings
- Message for function errors in multifunction display (A1p13)

Function sequence for recognition of driver activity
The following situations suggest driver activity and result in suppression of any pending warning:
- Turn signals
- Accelerate
- Brakes
- Steering intervention

Turn signaling:
The steering column tube module control unit (N80) directly reads in the position of the combination switch (S4) and sends this to the multifunction camera via the chassis CAN.

Acceleration:
Acceleration is recorded by the accelerator pedal sensor (B37).
The CDI control unit (N3/9) (with diesel engine) or the ME-SFI [ME] control unit (N3/10) (with gasoline engine) reads in the signals of the accelerator pedal sensor directly and forwards them on to the multifunction camera via the chassis CAN.

Brakes:
The brake light switch (S9/1) is supplied with power from circuit 15 via the front SAM control unit with fuse and relay module (N10/1).
When the service brake is being operated, the voltage that is present is switched through to the Electronic Stability Program control unit.
In addition, the Electronic Stability Program control unit evaluates the data from the yaw rate sensor for lateral and longitudinal acceleration (B24/15). These are sent by the yaw rate sensor for lateral and longitudinal acceleration to the Electronic Stability Program control unit via the vehicle dynamics CAN (CAN H).
The Electronic Stability Program control unit sends the status of the service brake system via the chassis CAN to the multifunction camera and video and radar sensor system control unit.

Steering intervention:
Steering movements are recorded by the steering angle sensor (N49).
The steering column tube module control unit reads in the steering angle sensor data and sends the data over the chassis CAN to the multifunction camera.
If the multifunction camera detects active corner cutting by the driver, crossing over the lane marking at an angle of > 3° or a lateral acceleration of a > 4 m/s 2, then a pending warning is also suppressed.

Function sequence for recognition of control interventions
All controls in the driver's immediate vicinity are monitored. If a control intervention is registered, the Automatic Lane Recognition system deems the driver to be "distracted". As soon as the vehicle drives over the lane marking, an active warning is output.
The control interventions are evaluated by the multifunction camera.
The multifunction camera adjusts the warning threshold accordingly depending on the frequency of actuation of the controls. This means that the automatic lane recognition function warns earlier and possibly more frequently.
The following controls are monitored:
- Audio system controls:
- Radio (A2) (with code (510) Audio 20 with CD changer or code (523) MB Audio 20 radio) or
- Radio with auto pilot system (A2/56) (with code (511) Audio 50 APS with DVD changer or code (525) MB Audio 50 APS radio) or
- COMAND controller unit (A40/3) (with code (512) COMAND APS with DVD changer or code (527) COMAND APS with single DVD drive (with navigation) or code (528) COMAND incl. DVD changer)
- Comfort function controls:
- Cruise control lever (S40/4)
- Driver-side power window and outside mirror adjustment switch group (S20) (only outside mirror adjustment)
- Steering column adjustment switch (S59) (with code (275) Memory package for electrically adjustable front seats)
- Left multifunction steering wheel button group (S110) or right multifunction steering wheel button group (S111)
- Interior illumination controls
- Front dome lamp switch (N70/3s4)
- Left front reading lamp switch (N70/3s6)
- Right front reading lamp switch (N70/3s7)
The control interventions are recorded as follows:
Control interventions on audio system:
Control interventions on the audio system control buttons are sent to the multifunction camera by the radio or the COMAND controller unit over the interior CAN, front SAM control unit and chassis CAN.
Control interventions on comfort functions:
Control interventions at the steering column adjustment controls, cruise control lever and multifunction steering wheel button groups are read in by the steering column tube module control unit and transmitted via chassis CAN to the multifunction camera.
Control interventions at the multifunction steering wheel button groups are read in directly by the steering wheel electronics (N135) and transmitted via the steering LIN (LIN E1) to the steering column tube module control unit.
Control interventions at the driver-side power window and outside mirror adjustment switch group (outside mirror adjustment only) are read in by the left front door control unit (N69/1) via the left door LIN (LIN B5) and transmitted via interior CAN, front SAM control unit and chassis CAN to the multifunction camera.

Interior illumination control interventions:
Control interventions at the interior illumination are read in directly by the front SAM control unit and transmitted via chassis CAN to the multifunction camera.
The overhead control panel electronics (N70/3) are connected directly to the front SAM control unit.

Function sequence for issuing warning
The warning is issued haptically by the steering wheel vibration motor, which is integrated into the multifunction steering wheel.
The multifunction camera transmits the request to actuate the steering wheel vibration motor via chassis CAN to the steering column tube module control unit and steering LIN to the steering wheel electronics. The steering wheel electronics then actuate the steering wheel vibration motor.
The steering wheel vibration motor is actuated for a duration of t = 1.5 s. This is felt by the driver as a vibration.
The intensity of the warning is adapted to the vehicle speed, to account for perceptible influences from the suspension at high speeds.
The warning is terminated when the triggering condition is no longer fulfilled or when driver activity is recognized (braking, accelerating and braking or turn signaling).
If during a warning a driver response is detected, e.g. steering back into the lane or turn signaling, the warning is also terminated.
The following situations will result in suppression of a warning output, because it is assumed that the driver activity is intentional:
- Status changes of steering wheel, brake or accelerator pedal
- Recognized "corner cutting" (by means of lane recognition and the current vehicle position the multifunction camera recognizes a road with bends and concludes "corner cutting"). Warnings about corner cutting are not issued until a defined lateral acceleration is reached.
- Active flashing function (corresponding turn signaling)
- Active or passive safety functions active
After warning suppression, a warning can only be output again after approx. t = 3 s or after t = 10 s in the case of turn signaling.
The corresponding information for suppression of the warning is received by the multifunction camera over the chassis CAN.
If "corner cutting" is recognized, a warning period delay occurs until a defined threshold (lateral acceleration dependent on ground speed) is reached, whereupon a warning is then issued.