Lane Keeping Assist, Function - GF54.71-P-0005RF
Model 205
up to model year 2019
with code 476 (Lane keeping assist)
Model 253 (except 253.99)
up to model year 2020
with code 476 (Lane keeping assist)
Function requirements, general
- Engine running or drive train operational.
- Lane Keeping Assist function switched on
The CDI control unit or the ME-SFI control unit sends the "Engine running" or "Drive train operational" signal to the mono multifunction camera via the drive train CAN, powertrain control unit and periphery CAN.
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 mono 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. 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 can be selected:
- Standard, sensitivity increased (warnings issued earlier and more frequently)
- Adaptive, sensitivity reduced (warnings issued later and less often) The instrument cluster sends the selected operating mode over the user interface CAN, electronic ignition lock control unit and the peripherals CAN to the mono multifunction camera.
Illustration of Lane Keeping Assist principle, shown on model 205.0
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 sends this via the chassis FlexRay, electronic ignition lock control unit and periphery CAN to the mono multifunction camera. The Electronic Stability Program control unit additionally sends the wheel speed via the chassis FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster. The instrument cluster calculates the vehicle speed to be displayed and sends it to the mono multifunction camera over the user interface CAN, electronic ignition lock control unit and periphery CAN.
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 mono multifunction camera is mounted at the top center of the windshield and records the road space in front of the vehicle. The mono multifunction camera 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
The mono multifunction camera calculates the lane based on two different lane algorithms that are implemented in the mono multifunction camera. If the comparison between the two lane algorithms results in a match, the mono multifunction camera uses the data to generate a safe lane.
The mono multifunction camera 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 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. If there are several markings present (e.g. in construction site zones), 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
- Cutting a tight corner
- Turn signals
- 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 reads in the signals from the steering wheel angle sensor directly and sends information regarding the steering angle via the chassis FlexRay, electronic ignition lock control unit and periphery CAN to the mono multifunction camera. Brakes:
The Electronic Stability Program control unit sends the status of the brake pedal via the chassis FlexRay, electronic ignition lock control unit and periphery CAN to the mono multifunction camera.
Acceleration:
The CDI control unit or the ME-SFI control unit sends information about the accelerator pedal position via the drive train CAN, powertrain control unit and periphery CAN to the mono multifunction camera.
Turn signaling:
The steering column tube module control unit directly reads in the switch position of the combination switch and sends it to the mono multifunction camera over the chassis FlexRay, electronic ignition lock control unit and periphery CAN.
Turn rate, lateral acceleration and longitudinal acceleration:
The acceleration/yaw rate is detected by the acceleration sensor integrated into the Supplemental Restraint System control unit. The supplemental restraint system control unit sends the corresponding values via the vehicle dynamics CAN to the Electronic Stability Program control unit. The Electronic Stability Program control unit evaluates the data and sends it via the chassis FlexRay, electronic ignition lock control unit and periphery CAN to the mono multifunction camera.
If the mono multifunction camera detects active corner cutting, crossing over of the road lane marking in an angle of ∠ > 3° or a lateral acceleration of a > 4 m/s2
, a pending warning is then also suppressed.
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". Control interventions are evaluated by the mono multifunction camera. The warning threshold is adjusted to match the control actuating frequency, i.e. Lane Keeping Assist warns earlier and possibly more often. 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 button
- 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 button
- Left front reading lamp button
- Right front reading lamp button
Control interventions on audio system:
The audio system is operated via the Audio/COMAND control panel. The control interventions on the Audio/COMAND control panel are received by the head unit over the telematics CAN. The head unit sends information on the control interventions on the audio system to the mono multifunction camera over the user interface CAN, electronic ignition lock control unit and periphery CAN.
Control interventions on comfort functions:
The steering column tube module control unit sends information on control interventions on the CRUISE CONTROL lever, steering column adjustment switch and multifunction steering wheel button group to the mono multifunction camera over the chassis FlexRay, electronic ignition lock control unit and periphery CAN.
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.
The left front door control unit reads in the control signals of the driver-side power window and outside mirror adjustment switch group over the left front door LIN and sends them to the mono multifunction camera over the interior CAN, electronic ignition lock control unit and periphery CAN.
Interior illumination control interventions:
The overhead control panel control unit directly reads in the status of the interior lamp automatic function button and the front reading lamp buttons and sends it to the front SAM control unit over the roof LIN. The front SAM control unit sends it to the mono multifunction camera over the interior CAN, electronic ignition lock control unit and periphery CAN.
Additional function requirements for warning output
- Lane recognition by the mono multifunction camera
- Vehicle speed v = 60 to 200 km/h
- Radius of curve r > 150 m
- Leaving of lane recognized
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 mono multifunction camera transmits the request to actuate the steering wheel vibration motor to the steering column tube module control unit over the periphery CAN, electronic ignition lock control unit and chassis FlexRay.
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 to cover for perceptible influences from 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" operating 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 the Electronic Stability Program (ESP®))
In "Adaptive" operating 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
A renewed warning display is only possible after a suppression (driver activity, trigger conditions not given) in the "Standard" mode after approx. t = 3 s, in the "Adaptive" mode after approx. t = 5 s and after turn signaling after t = 10 s.
By means of lane recognition and the current vehicle position, the mono 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.
The corresponding information for suppression of the warning is received by the mono multifunction camera over the periphery CAN. If "corner cutting" is detected, the warning is delayed until a defined threshold (lateral acceleration depending on ground speed) is reached.
Afterwards, a warning is output.
| Electrical function schematic for Lane Keeping Assist | PE54.71-P-2057-97FBA | ||
| Overview of system components for driver assistance systems | Model 205 up to model year 2019 with code 476 (Lane keeping assist) Model 253 (except 253.99) up to model year 2020 with code 476 (Lane keeping assist) |
GF54.00-P-9998RF |