Lane Keeping Assist, Function - GF54.71-P-0005FQ
MODEL 218
up to year 2015
with CODE 476 (Lane keeping assist)
Up to 28.02.2013
As of 01.03.2013
Function requirements, general
- Terminal 15 ON
- Function enabled in instrument cluster
- Vehicle speed: Warning at v = 60 to 270 km/h
- Recognizable lane markings present on both sides (no construction site markings (yellow/white), no snow, not covered up, etc.; in other words, 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 to the multifunction camera in vehicles up to 28.02.2013 via the chassis CAN or in vehicles as of 01.03.2013 via chassis CAN 1, the front SAM control unit and chassis CAN 2.
Lane Keeping Assist, general
The Lane Keeping Assist detects any unintentional driving across lane markings and issues a haptic warning to the driver in certain situations by 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 Lane Keeping Assist takes the driver's behavior into consideration and decides the point at which a warning is to be issued.
In model 218.9 and in model 218.3 as of 01.06.2012, the driver has the option of adjusting the sensitivity of the Lane Keeping Assist in the "Assistance" menu of the instrument cluster. The instrument cluster transmits the appropriate setting via the chassis CAN (up to 28.02.2013) or chassis CAN 2 (as of 01.03.2013) to the multifunction camera.
The following operating modes can be selected:
- Standard (sensitivity high, warnings issued earlier and more frequently)
- Adaptive (sensitivity low, warnings issued later and less often) Under the following conditions any driving over lane markings is detected, but a warning is not issued:
- Driver activity through evaluation of steering wheel movements, brake requests and accelerator pedal position
- Sporty cornering (corner cutting)
- Turn signals
- Active control interventions by braking assistance systems
Illustration of the principle of Lane Keeping Assist, shown on model 218.3
Lane Keeping Assist operates on a speed-dependent basis and therefore requires the vehicle speed to be calculated. This is defined by the wheel speeds. The wheel speeds are detected by the RPM sensors. The Electronic Stability Program control unit reads in the signals from the RPM sensors directly and transmits them to the instrument cluster via the chassis CAN in vehicles up to 28.02.2013 or via chassis CAN 1, the front SAM control unit and chassis CAN 2 in vehicles as of 01.03.2013. The instrument cluster calculates the vehicle speed and transmits it via the chassis CAN (up to 28.02.2013) or chassis CAN 2 (as of 01.03.2013) to the multifunction camera.
The Lane Keeping Assist consists of 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 is located at the top center of the windshield. It optically monitors the road in front of the vehicle. To do this, the multifunction camera records pictures of the lane at a fixed scanning rate and makes these pictures available to the integrated control unit. The multifunction camera measures the lane based on the lane markings.
Schematic of lane recognition by multifunction camera
Based on the recorded image sequences and the measurement values resulting from the pictures of the lane markings, the multifunction camera calculates a lane. This calculation is based on a corresponding algorithm. On the basis of this data, the multifunction camera determines the relative position of the vehicle in the lane. The Lane Keeping Assist measures are all derived from this position. No lane information can be issued in cases where there are no lane markings or if they are not visible (e.g. owing to dirt or snow), where there is a low contrast between the road surface and the lane markings 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.
In construction site areas, the Lane Keeping Assist may be unable to issue warnings due to multiple markings.
The current status of the Lane Keeping Assist, especially the warning readiness, is indicated continuously in the multifunction display of the instrument cluster. This status information is transmitted by the multifunction camera via the chassis CAN (up to 28.02.2013) or chassis CAN 2 (as of 01.03.2013) to the instrument cluster.
Possible displays:
- Function status
- Icon off: Lane Keeping Assist deactivated
- Icon yellow (1): Lane Keeping Assist activated but not ready to issue warnings (e.g. v < 60 km/h)
- Warning readiness
- Icon green (2): Lane Keeping Assist activated and ready to issue warnings
- Message for brake interventions and system errors in multifunction display
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 reads in the switch position of the combination switch directly and transmits it to the multifunction camera via the chassis CAN in vehicles up to 28.02.2013 or via chassis CAN 1, the front SAM control unit and chassis CAN 2 in vehicles as of 01.03.2013.
Acceleration:
The accelerator pedal sensor registers any accelerator pedal actuation. The CDI control unit or the ME-SFI control unit reads in the signals of the accelerator pedal sensor directly and transmits them to the multifunction camera via the chassis CAN in vehicles up to 28.02.2013 or via chassis CAN 1, the front SAM control unit and chassis CAN 2 in vehicles as of 01.03.2013.
Brakes:
Operation of the brake pedal is detected by the brake lights switch. The Electronic Stability Program control unit reads in the status of the brake light switch directly and generates the "Brake" request from it. The Electronic Stability Program control unit also evaluates the data from the yaw rate sensor for lateral and longitudinal acceleration. The yaw rate sensor for lateral and longitudinal acceleration communicates over the vehicle dynamics CAN with the Electronic Stability Program control unit.
The Electronic Stability Program control unit transmits the information on the status of the service brake and on the momentum of the vehicle to the multifunction camera via the chassis CAN in vehicles up to 28.02.2013 or via chassis CAN 1, the front SAM control unit and chassis CAN 2 in vehicles as of 01.03.2013.
Steering intervention:
Steering movements are detected by the steering angle sensor. The steering column tube module control unit reads in the signals of the steering angle sensor directly and transmits them to the multifunction camera via the chassis CAN in vehicles up to 28.02.2013 or via chassis CAN 1, the front SAM control unit and chassis CAN 2 in vehicles as of 01.03.2013.
If the multifunction camera detects active corner cutting, crossing over of the lane marking at an angle ∠ > 3° or a lateral acceleration of a > 4 m/s2
, a pending warning is suppressed here too.
Function sequence for recognition of control interventions
All controls in the driver's immediate vicinity are monitored. If a control intervention is registered, the Lane Keeping Assist deems the driver to be "distracted". As soon as the vehicle drives over the lane marking, an active warning is output. Evaluation of control interventions is carried out by the multifunction camera. The warning threshold is adjusted according to the operating frequency of the controls. In other words, the Lane Keeping Assist system warns earlier and possibly even more often. The following controls are monitored:
- Audio system controls
- Radio (with code 523 (Audio 20 CD) or code 510 (Audio 20 CD with 6-disk CD-changer)) or
Radio with Auto Pilot System (with code 525 (MB Audio 50 APS radio) or code 511 (Audio 50 APS incl. DVD changer)) or COMAND controller unit (with code 512 (COMAND APS incl. DVD changer), code 526 (COMAND with single DVD drive (without navigation)), code 527 (COMAND APS with single DVD drive (with navigation)) or code 528 (COMAND incl. DVD changer))
- Radio (with code 523 (Audio 20 CD) or code 510 (Audio 20 CD with 6-disk CD-changer)) or
- 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 (with code 275 (Memory Package), without code 443 (Steering wheel heater)) or steering column adjustment and steering wheel heater switch (with code 275 (Memory Package) and code 443 (Steering wheel heater))
- Left multifunction steering wheel button group
- 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:
The radio or the COMAND controller unit transmits information about control interventions on the audio system to the multifunction camera via the interior CAN, the front SAM control unit and the chassis CAN (up to 28.02.2013) or chassis CAN 2 (as of 01.03.2013).
Control interventions on comfort functions:
The control interventions on the steering column adjustment switch, the TEMPOMAT lever and the multifunction steering wheel button groups are read in by the steering column tube module control unit, which transmits this information to the multifunction camera via the chassis CAN in vehicles up to 28.02.2013 or via chassis CAN 1, the front SAM control unit and chassis CAN 2 in vehicles as of 01.03.2013.
The steering wheel electronics read in the control interventions on the multifunction steering wheel button groups directly and transmit this information to the steering column tube module control unit via the steering LIN.
The left front door control unit reads in the control interventions on the power window and outside mirror adjustment switch group on the driver's side (outside mirror adjustment only) via the left front door LIN and transmits this information to the multifunction camera via the interior CAN, the front SAM control unit and the chassis CAN (up to 28.02.2013) or chassis CAN 2 (as of 01.03.2013).
Control interventions on interior lighting (with code 414 (Sliding sunroof)): The statuses of the front dome lamp switch and the front reading lamp switch are read in directly by the overhead control panel control unit, which transmits this information to the multifunction camera via the interior CAN, the front SAM control unit and the chassis CAN (up to 28.02.2013) or chassis CAN 2 (as of 01.03.2013).
Control interventions on interior lighting (without code 414 (Sliding sunroof)):
The status of the front dome lamp switch and the front reading lamp switch is read in directly by the front SAM control unit via the overhead control panel electronics. The front SAM control unit transmits this information to the multifunction camera via the chassis CAN (up to 28.02.2013) or chassis CAN 2 (as of 01.03.2013).
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 for actuation of the steering wheel vibration motor to the steering column tube module control unit via the chassis CAN in vehicles up to 28.02.2013 or via chassis CAN 2, the front SAM control unit and chassis CAN 1 in vehicles as of 01.03.2013. The steering column tube module control unit transmits this request via 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. The intensity of the haptic warning is adapted to the vehicle speed, to cover for perceptible influences from the suspension at high speeds.
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
Vehicles up to 31.05.2012:
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. Vehicles as of 01.06.2012:
Following suppression, the next warning can be issued in "Standard" mode only after approx. t = 3 s, in "Adaptive" mode only after approx. t = 5 s and following turn signaling only after t = 10 s.
The appropriate information for suppressing the warning is received by the multifunction camera via the chassis CAN (up to 28.02.2013) or chassis CAN 2 (as of 01.03.2013).
If corner cutting is detected, the warning is delayed until a defined threshold (lateral acceleration relative to vehicle speed) is reached. Only then is a warning issued.
| Electrical function schematic for Lane Keeping Assist | Model 218 up to model year 2014 with code 476 (Lane keeping assist) | PE54.71-P-2057-97XAA | |
| Model 218 as of model year 2014 up to model year 2015 with code 476 (Lane keeping assist) | PE54.71-P-2057-97XAB | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998FQ |