Lane Keeping Assist, function - GF54.71-P-0005GN

MODEL 166 as of model year 2016 with CODE 476 (Lane keeping assist)

MODEL 292 with CODE 476 (Lane keeping assist)

Block diagram, except model 166.063

Fig 1: Lane Keeping Assist Block Diagram - Except Model 166.063

Courtesy of MERCEDES-BENZ USA

Block diagram, model 166.063

Fig 2: Lane Keeping Assist Block Diagram - Model 166.063

Courtesy of MERCEDES-BENZ USA

Function requirements, general

Engine running or drive train operational
Lane Keeping Assist function switched on

The CDI control unit or ME-SFI [ME] control unit transmits the "engine running" signal or "drivetrain operational" signal over chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

The ME-SFI [ME] control unit transmits the "engine running" signal or "drivetrain operational" signal over the engine CAN, powertrain control unit, chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

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 (with CODE 22P (Lane package)).

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. An option is available here to the driver to configure the sensitivity of the Lane Keeping Assist in the instrument cluster's "Assistance" menu.

The following operating modes are available for selection:

Standard, sensitivity increased (warnings issued earlier and more frequently)
Adaptive, sensitivity reduced (warnings issued later and less often) The instrument cluster transmits the selected operating mode via chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

Illustration of the principle of Lane Keeping Assist

Fig 3: Overview Of Lane Keeping Assist Principle

Courtesy of MERCEDES-BENZ USA

Warnings are issued as soon as the vehicle is in the direct vicinity of a broken or solid line or crosses over it.

Lane Keeping Assist operation is speed-dependent. The vehicle speed is calculated from the wheel speed. The Electronic Stability Program control unit transmits this via chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)). The Electronic Stability Program control unit also sends the wheel speed via the chassis CAN 1, electronic ignition lock control unit, and chassis CAN 2 to the instrument cluster. The instrument cluster calculates the vehicle speed to be displayed and transmits it via chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

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

Additional function requirements for lane recognition

Detectable lane marking present on both sides (no construction site markings (ambiguous markings), no snow, not covered etc., i.e. not enough contrast)
Two lane dividers present

Function sequence for lane recognition

The multifunction camera (with CODE 22P (Lane package)) is mounted at the top center of the windshield and it records the road space in front of the vehicle. The multifunction camera (with CODE 22P (Lane package)) records pictures of the lane at a fixed scanning rate and makes these pictures available to the integrated control unit.

Schematic of lane recognition by multifunction camera

Fig 4: Display - Stereo Multifunction Camera Screen (Lane Recognition)

Courtesy of MERCEDES-BENZ USA

The multifunction camera (with CODE 22P (Lane package)) calculates the lane based on two different lane algorithms that are implemented in the multifunction camera (with CODE 22P (Lane package)). If the comparison between the two lane algorithms results in a match, the multifunction camera (with CODE 22P (Lane package)) uses the data to generate a safe lane.

The multifunction camera (with CODE 22P (Lane package) uses this data to calculate the relative position of the vehicle in the lane. The Active Lane Keeping Assist measures are all derived from this position. No lane information can be issued in cases where no lane markings are present or are not visible (e.g. due to dirt or snow), where there is insufficient 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. If there are several markings present (e.g. in construction site zones), the Lane Keeping Assist may not be ready to issue a warning. If tar joints in the road surface are interpreted as lane markings, a warning is suppressed.

Function sequence for recognition of driver activity

The following situations suggest driver activity and result in suppression of any pending warning:

Clearly active steering (steering intervention), braking or accelerating
Turn signals
Cutting a tight corner
Sporty driving (high cornering speeds or heavy acceleration)

Steering:

Steering movements are recorded by the steering wheel angle sensor. The steering column tube module control unit directly reads in the signals of the steering wheel angle and sends information on the steering wheel angle via chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

Brakes:

The Electronic Stability Program control unit transmits the status of the brake pedal via chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

Acceleration:

The CDI control unit or the ME-SFI [ME] control unit sends information on the accelerator pedal position over chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package).

The ME-SFI [ME] control unit sends information on the accelerator pedal position over the engine CAN, powertrain control unit, chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package).

Turn signaling:

The steering column tube module control unit reads in the position of the combination switch directly and transmits it to the multifunction camera (with CODE 22P (Lane package)) via chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2.

Turn rate, lateral acceleration and longitudinal acceleration:

The acceleration/yaw rate is detected by the yaw rate sensor for lateral and longitudinal acceleration. The yaw rate sensor for lateral and longitudinal acceleration transmits appropriate values via the dynamics CAN to the Electronic Stability Program control unit. The Electronic Stability Program control unit evaluates the data and transmits it via chassis CAN 1, the electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

If the multifunction camera (with CODE 22P (Lane package)) detects active corner cutting, crossing over of the lane marking at an angle of ∠ > 3° or a lateral acceleration of a > 4 m/s 2, a pending angle warning is suppressed here too.

Function sequence for recognition of control interventions

Controls located in close proximity of the driver and that affect the attention of the driver when they are operated are monitored. If a control intervention is registered, the Lane Keeping Assist deems the driver to be "distracted". The control interventions are evaluated by the multifunction camera (with CODE 22P (Lane package)). The warning threshold is adapted to the frequency with which the controls are actuated, i.e. the Lane Keeping Assist provides warnings sooner and more frequently if necessary. An active warning is output as soon as the vehicle is in the direct proximity of or crosses over the lane marking.

The following controls are monitored:

Audio system controls
Comfort function controls:
- Cruise control lever
- Steering column adjustment switch (with CODE 275 (Memory package))
- Left multifunction steering wheel button group or right multifunction steering wheel button group
- Driver-side power window and outside mirror adjustment switch group (only the outside mirror adjustment is monitored)
Interior illumination controls:
- Interior lamp automatic function switch
- Left front reading lamp switch
- Right front reading lamp switch

Control interventions on audio system:

The audio system is operated via the Audio/COMAND control panel or via the touchpad (with CODE 531 (COMAND APS)). The control interventions at the Audio/COMAND control panel are received via the telematics CAN from the radio (with CODE 505 (Radio 20 NTG5 non navigation-capable), with CODE 522 (Audio 20 radio)) and at the touchpad (with CODE 531 (COMAND APS)) from the COMAND controller unit (with CODE 531 (COMAND APS)). The radio (with CODE 505 (Radio 20 NTG5 non navigation-capable), with CODE 522 (Audio 20 radio)) or the COMAND controller unit (with CODE 531 (COMAND APS)) sends information about the control interventions at the audio system via interior CAN, electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

Control interventions on comfort functions:

The steering column tube module control unit sends information on the control interventions at the CRUISE CONTROL lever, at the steering column adjustment switch (with CODE 275 (Memory package)) and at the multifunction steering wheel button groups via chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

The steering wheel electronics reads in the control signals on the multifunction steering wheel button groups directly and transmit them to the steering column tube module control unit over the steering LIN. Control signals at the driver-side power window and outside mirror adjustment switch group are read in by the left front door control unit over the left front door LIN and sent over the interior CAN, electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

Interior illumination control interventions:

The status of the interior lights automatic function switch and the front reading lamp switch are read in directly by the overhead control panel control unit and transmitted via the roof LIN to the SAM control unit. The SAM control unit transmits these statuses via the interior CAN, electronic ignition lock control unit and chassis CAN 2 to the multifunction camera (with CODE 22P (Lane package)).

Additional function requirements for warning output

Lane recognition by multifunction camera (with CODE 22P (Lane package))
Vehicle speed v = 60 to 200 km/h
Radius of curve = r > 150 m
Exiting of lane recognition

Function sequence for issuing warning

The warning is issued haptically by the steering wheel vibration motor, which is integrated in the multifunction steering wheel. The multifunction camera (with CODE 22P (Lane package)) transmits the request to actuate the steering wheel vibration motor via chassis CAN 2, the electronic ignition lock control unit and chassis CAN 1 to the steering column tube module control unit. The steering column tube module control unit sends this request over the steering LIN to the steering wheel electronics, which then actuates 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 in order to allow for the perceivable effects of the suspension at high speeds.

The warning is suppressed when the triggering conditions are no longer given or when driver activity is detected (braking, accelerating, steering or turn signaling).

In "Standard" mode, a haptic warning is suppressed under the following prerequisites:

Turn signaling recognized (the warnings are suppressed for a certain period of time)
Intervention of a driving safety system recognized (e.g. by ESP®)

In "Adaptive" mode, a haptic warning is suppressed under the following prerequisites:

Turn signaling recognized (the warnings are suppressed for a certain time period)
Intervention of a driving safety system recognized (e.g. by ESP®)
During heavy acceleration (e.g. kickdown)
During strong braking
During rapid steering movements (e.g. during an evasive maneuver or during a rapid lane change)
Corner cutting recognized

Following suppression (driver activity, triggering condition not given), a new 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.

By means of lane recognition and the current vehicle position, the multifunction camera (with CODE 22P (Lane package)) recognizes a road with bends and concludes "corner cutting". Warnings about corner cutting are not issued until a defined lateral acceleration is reached.

The corresponding information on warning suppression is received by the multifunction camera (with CODE 22P (Lane package)) over chassis CAN 2. If "corner cutting" is detected, the warning time is postponed until a defined threshold (lateral acceleration dependent on vehicle speed) has been reached. Afterwards, a warning is output.

	Electrical function schematic for Lane Keeping Assist		PE54.71-P-2057-97NBA
	Overview of system components for driver assistance systems		GF54.00-P-9998GN