Automatic lane recognition, function - GF54.71-P-0002CE

MODEL 204.0/2 

with CODE (476) Automatic lane recognition 

as of model year 2012 

/YoM 11 model refinement package 

MODEL 204.3 with CODE (476) Automatic lane recognition 

Function requirements, general 

• Circuit 15 ON
• Function enabled via the instrument cluster
• Vehicle speed:
  • Warning at v = 60 to 270 km/h
  • Intervention by the brake system at v = 60 up to 200 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 transmits the circuit status of circuit 15 over chassis CAN.

Automatic lane recognition, general 

The automatic lane recognition system 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. The automatic lane recognition system 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:

• For driver activities through evaluation of steering-wheel movement, brake requests and the accelerator pedal position
• For sporty cornering (cutting corners)
• When turn signaling
• For active control intervention functions by the brake assist system

Illustration of the principle of automatic lane recognition 

The Automatic Lane Recognition system operates on a speed-dependent basis and therefore it requires the speed to be calculated, and this is defined by the wheel speeds.

The wheel speeds are recorded by the following components:

• Left front axle speed sensor
• Right front axle speed sensor
• Left rear axle speed sensor
• Right rear axle speed sensor

The Electronic Stability Program control unit reads in the signals from the RPM sensors directly and sends them over Chassis CAN to instrument cluster and multifunction camera.

The Automatic Lane Recognition system 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 monitors the road space in front of the vehicle.

To this end, the multifunction camera uses a fixed scan rate to document pictures of the lane and then sends them to the control unit integrated into the multifunction camera.

The multifunction camera then 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 system 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 area the system 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:

• System status
  • Icon off: Automatic Lane Recognition deactivated
  • Icon yellow (1): Automatic Lane Recognition activated, but not ready to issue warnings

  (e.g. v < 60 km/h)

• Warning readiness
  • Icon green (2): Automatic Lane Recognition activated and ready to issue warnings
• Message for system 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

The situations listed here are recorded by the corresponding components and sent over the chassis CAN to the front SAM control unit and over the front end CAN to the multifunction camera.

Turn signaling:

The signals from the combination switch are read in by the steering column tube module control unit and sent over the chassis CAN.

Acceleration:

Operation of the accelerator pedal is registered by the accelerator pedal sensor. The signals from the accelerator pedal sensor are read in directly by the CDI control unit or ME-SFI [ME] control unit and sent over the chassis CAN to the ESP control unit.

Brakes:

The status of the service brake is recorded by the brake lights switch, which is read in directly by the Electronic Stability Program control unit.

In addition to this, the data of the yaw rate sensor for lateral and longitudinal acceleration are recorded, which sends its data over the vehicle dynamics CAN to the Electronic Stability Program control unit.

Steering intervention:

The signal from the steering wheel angle sensor is sent by the steering column tube module control unit over chassis CAN.

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 detected, the Automatic Lane Recognition system regards the driver to be "distracted" and an active warning is issued as soon as the vehicle crosses over the lane marking. The control interventions are recorded by the multifunction camera. The warning threshold is adapted to match the control actuating frequency, i.e. the Automatic Lane Recognition system warns earlier and possibly more often.

The following controls are monitored:

• Audio system controls
  • Radio or
  • COMAND controller unit
• Comfort function controls
  • Cruise control lever
  • Driver-side power window and outside mirror adjustment switch group

    (only the outside mirror adjustment is monitored)

  • Steering column adjustment switch
  • Left multifunction steering wheel button group or right multifunction steering wheel button group
• Interior illumination controls:

• Front dome lamp switch
• Left front reading lamp switch
• Right front reading lamp switch

Control interventions on audio system:

Control interventions on the audio system controls are sent to the multifunction camera through the radio or the COMAND controller unit over the body CAN, front SAM control unit and the front end CAN.

Control interventions on comfort functions:

The control interventions on the steering column adjustment and the cruise control lever are read-in directly by the steering column tube module control unit.

The steering column tube module control unit also reads in the control interventions from the multifunction steering wheel button groups through the steering wheel electronics over the steering LIN.

The steering column tube module control unit sends this information over the chassis CAN to the front SAM control unit.

The control interventions on the driver-side power window and outside mirror adjustment switch group are registered by the left front door control unit over the left door LIN. The left front door control unit sends this information over the interior CAN to the front SAM control unit.

Control interventions on the interior illumination (with code (414) Power glass tilting/sliding roof):

Control interventions on the interior illumination are registered by the overhead control panel control unit, which sends the information on the control interventions over the chassis CAN.

Control interventions on the interior illumination (without code (414) Power glass tilting/sliding roof):

Control interventions on the interior illumination are registered by the front SAM control unit.

The front SAM control unit routes the information on audio system, comfort functions and interior illumination control interventions over the front end CAN to the multifunction camera.

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 sends a request over chassis CAN to actuate the steering wheel vibration motor to the front SAM control unit, which forwards the request over chassis CAN to the steering column tube module control unit.

The steering column tube module control unit forwards the request over the steering LIN to the steering wheel electronics which actuate the steering wheel vibration motor.

The steering wheel vibration motor is actuated for a duration of t = 1.5 s and the driver feels the vibration.

The intensity of the vibration is adapted to the vehicle speed, to cover for perceptible influences from the suspension at high speeds.

The warning is terminated by the discontinuity of the triggering conditions 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 systems active

The next possible warning output, after a warning output has been suppressed, takes place after approx. t = 3 s and generally after turn signaling for t = 10 s.

The corresponding information for suppression of the warning is received by the multifunction camera over the front end 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

	Electrical function schematic for automatic lane recognition		PE54.71-P-2052-97FAA
	Overview of system components for automatic lane recognition		GF54.00-P-9998CE