Active Lane Keeping Assist, Function - GF54.71-P-0004LFM
Model 217, 222
as of model year 2018
with code 23P (Driving Assistance package)
except code 243 (Active lane keeping Assist)
Shown on model 217, 222 as of 01.06.2018
Shown on model 217, 222 up to 31.05.2018
Function requirements, general
- Engine running or drive train operational:
The CDI control unit or the ME-SFI control unit sends the "engine running" or "drivetrain operational" signal via the drive CAN, powertrain control unit and suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera.
- Front radar sensor system soiling and function test completed successfully:
Object detection (e.g. vehicle directly ahead) through the radar sensor system is based on the radar measuring procedure. Each time the engine is started, the short-range and long-range radar sensor performs a soiling and function test in order to ensure that the radar sensor is functioning correctly. The function test requires an object to be positioned in the detection range. If a malfunction is established or if there are no objects in the detection area, Active Lane Keeping Assist cannot be activated. If the short-range and long-range radar sensor is functioning correctly, it sends the "radar sensor system operational" status via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
- Stereo multifunction camera soiling and function test:
The stereo MFK performs a soiling and function test to ensure proper operation after each engine start. The function test requires an object to be located in the detection area (this object is used as a reference value). If a malfunction is established or if there are no objects in the detection area, Active Lane Keeping Assist cannot be activated. The stereo multifunction camera sends the status via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Illustration of principle shown on model 222
Active Lane Keeping Assist, general
Active Lane Keeping Assist detects when lane markings are crossed over and warns the driver haptically as of 01.06.2018 through vibrations of the steering gear or up to 31.05.2018 through vibrations on the steering wheel generated by the steering wheel vibration motor. As of 01.06.2018 with code 498 (Japan version), a visual warning is also issued on the instrument cluster. The stereo multifunction camera sends the corresponding request to the instrument cluster via the chassis FlexRay, electronic ignition lock control unit and user interface CAN.
Crossing over lane markings is optically recorded and processed by the stereo multifunction camera.
Active Lane Keeping Assist takes the driver's behavior into consideration and decides the point at which a warning is to be issued. Depending on the situation, the Mercedes-Benz Intelligent Drive control unit triggers targeted brake applications to move the vehicle back into the lane.
If the driver indicates that he/she is "active" before or during the intervention by the brake system, the intervention by the brake system is suppressed or canceled.
Brake intervention by the Active Lane Keeping Assist is suppressed or immediately aborted if there is active control by one of the following systems:
- Electronic Stability Program (ESP®)
- Anti-lock braking system (ABS)
- Acceleration slip regulation (ASR)
- Active Brake Assist with intersection function
- Active Blind Spot Assist
Warnings are issued as soon as the vehicle is in the direct vicinity of a broken or solid line or crosses over it.
Interventions by the brake system occur when pulling up to or when crossing a continuous line (lane delimitation) when the lane is delimited by two lane markings or, in the case of a broken line, when there is a vehicle in the oncoming lane or on a lane running in parallel in a collision-critical area.
The Active Lane Keeping Assist comprises the following subfunctions:
- Function sequence for Active Lane Keeping Assist ON and OFF
- Function sequence for lane recognition
- Function sequence for recognition of oncoming traffic/parallel traffic
- Function sequence for recognition of driver activity
- Function sequence for recognition of control interventions
- Function sequence for issuing warning
- Function sequence for active intervention by the brake system
Function sequence for Active Lane Keeping Assist ON and OFF
The Active Lane Keeping Assist can be switched off and on by pressing the Active Lane Keeping Assist button in the driver side instrument panel button group.
As of 01.06.2018 with code 51B (Euro NCAP):
The button to switch off Active Lane Keeping Assist must be pressed and held down until the LED goes out. Switch off is only possible for the current ignition sequence.
The front SAM control unit reads in the status of the Active Lane Keeping Assist button via the instrument panel LIN and sends the status via the interior CAN, electronic ignition lock control unit and suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera. As of 01.06.2018 with code 51B (EURO-NCAP) the instrument cluster's multifunction display shows a permanent status display. As of 01.06.2018 without code 51B (EURO-NCAP) and up to 31.05.2018 the instrument cluster's multifunction display shows the "Lane Keeping Assist ON/OFF" message. For this purpose, the Mercedes-Benz Intelligent Drive control unit sends the request via the suspension FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster.
The driver also has the option of configuring the settings for the Active Lane Keeping Assist in the head unit's "Assistance" menu. The following options are available for navigating in the control menu:
- With code 448 (Touchpad) navigation can be operated using the Audio/COMAND control panel. The corresponding control signals are sent by the Audio/COMAND control panel (except code 446 (Touchpad only)) over the telematics CAN to the head unit.
- With code 446 (Touchpad only) or code 448 (Touchpad), navigation can be performed using the touchpad. The corresponding control signals are sent by the touchpad (with code 446 (Touchpad only) or code 448 (Touchpad)) over the telematics CAN to the head unit.
- Navigation can be performed by voice control. The driver hands-free system microphone is read directly by the head unit.
- Navigation can be performed via the head unit finger navigation pad and the "Back" button on the steering wheel. The corresponding operation signals are sent by the head unit finger navigation pad and the "Back" button over the steering wheel electronics, steering wheel CAN, steering column tube module control unit, suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the head unit.
- With code 448 (Touchpad) the control menu can be activated with the "CAR" button on the Audio/COMAND control panel. The status of the "CAR" button is sent by the Audio/COMAND control panel over the telematics CAN to the head unit.
With code 446 (Touchpad only) the control menu can be activated using the "CAR" button on the lower control panel. The status of the "CAR" button is sent by the lower control panel over the LCP-LIN, touchpad (with code 446 (Touchpad only)) and the telematics CAN to the head unit.
The head unit sends the selected operating mode via the user interface CAN, electronic ignition lock control unit and suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera. The Mercedes-Benz Intelligent Drive control unit stores the current operating mode and, when restarted, sends it via the suspension FlexRay, electronic ignition lock control unit and user interface CAN to the head unit.
As of 01.06.2018 with code 51B (Euro NCAP) the following operating modes can be selected for the intervention:
- Standard (interventions in critical situations only)
- Sensitive (interventions on all the detected lines)
As of 01.06.2018 the warning can be switched on or off.
Up to 31.05.2018 the following operating modes are available for the warning:
- Standard (Sensitivity increased, warnings issued earlier and more frequently)
- Adaptive (reduced sensitivity, warnings issued later and less often)
Active Lane Keeping Assist operation is speed-dependent. The vehicle speed is calculated from the wheel speed. The Electronic Stability Program control unit sends it via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera. The Mercedes-Benz Intelligent Drive control unit and the stereo multifunction camera use the wheel speed signals to calculate the vehicle speed.
Additional function requirements for lane recognition
- As of 01.06.2018 with code 51B (EURO-NCAP): A detectable lane marking (continuous line) is available on at least one side (no construction-site markings (ambiguous markings), no snow, not covered up etc.).
- As of 01.06.2018 without code 51B (EURO-NCAP) and up to 31.05.2018: Recognizable lane markings are available on both sides (no construction site markings (ambiguous markings), no snow, not covered up etc.).
- Forward travel recognized and gear range "D" selected:
The direction of travel is defined using the wheel rotation direction. The Electronic Stability Program control unit sends the corresponding information via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera.
The fully integrated transmission control unit sends information on the engaged drive range via the drive train CAN, powertrain control unit and suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera.
Function sequence for lane recognition
The stereo multifunction camera is mounted at the top center of the windshield and records the road space in front of the vehicle. The stereo multifunction camera documents images of the lane at a fixed scanning rate, uses them to calculate the lane data and sends this data via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Schematic of lane recognition by stereo multifunction camera
The stereo multifunction camera calculates the lane on the basis of two different lane algorithms that are implemented in the stereo multifunction camera. If a comparison of the two lane algorithms results in a match, the stereo multifunction camera uses it to generate a safe lane.
The stereo 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.
As of 01.06.2018 with code 51B (EURO-NCAP) and with sensitive operating mode selected, and with only one lane marking recognized (continuous line) a virtual second line is generated to form a driving corridor. An intervention can only be applied to the existing lane marking however.
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 Active Lane Keeping Assist may not be ready to issue a warning. If tar seams in the road surface are interpreted as lane markings, a warning is suppressed or an unauthorized warning is output.
Function sequence for recognition of oncoming traffic/parallel traffic
Vehicles that are in the oncoming lane or on the lane running parallel are detected by the short-range and long-range radar sensor and the stereo multifunction camera. The Mercedes-Benz Intelligent Drive control unit receives the signals from the short-range and long-range radar sensor and the stereo multifunction camera, performs a plausibility check on the signals and evaluates them.
The Mercedes-Benz Intelligent Drive control unit reads in the signals from the short-range and long-range radar sensor via the suspension FlexRay. The Mercedes-Benz Intelligent Drive control unit reads in the signals from the rear outer bumper radar sensors on the left and right via radar CAN 2.
The stereo multifunction camera determines the values for the width and course of the lane and sends them via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Based on values such as the speed of the two vehicles, the respective relative position on the lane and the course of the lane, the Mercedes-Benz Intelligent Drive control unit determines whether a course-correcting wheel-specific brake application is required.
The following situations can lead to a course-correcting brake intervention when changing to the parallel lane/oncoming lane:
- Approaching vehicle in the oncoming lane
- Slower vehicle to be passed in the parallel lane
- Overtaking vehicle in the parallel lane
- Vehicle in the parallel lane (at approximately the same level)
- Guardrails or a series of stationary vehicles behind the lane markings
Approaching vehicle in oncoming lane, shown on model 222
Vehicles in the oncoming lane are detected by the following radar sensors depending on the distance and the angle to the vehicle with Active Lane Keeping Assist:
- Short and long-range radar sensor
- Stereo multifunction camera
Slow vehicle to be passed in the parallel lane, shown on model 222
Vehicles in the right or left parallel lane in the area ahead are recognized by the following radar sensors depending on the side of the lane, the distance and the angle to the vehicle with Active Lane Keeping Assist:
- Short and long-range radar sensor
- Stereo multifunction camera
Passing vehicle in the parallel lane, shown on model 222
Vehicles approaching from behind with a high relative speed compared to the vehicle with Active Lane Keeping Assist are recognized by the following radar sensors depending on the side of the lane, the distance and the angle to the vehicle with Active Lane Keeping Assist:
- Right outer rear bumper radar sensor
- Left outer rear bumper radar sensor
Vehicle in parallel lane at approximately same level as vehicle with Active Lane Keeping Assist, shown on model 222
Vehicles in the right or left parallel lane level with the vehicle with Active Lane Keeping Assist are detected by the following radar sensors depending on which lane and on the distance and angle to the vehicle with Active Lane Keeping Assist:
- Right outer rear bumper radar sensor
- Left outer rear bumper radar sensor
The following situations can lead to a cancellation of the course-correcting brake intervention:
- Vehicle detected with short distance in the rear area in own lane (tailgating scenario)
- Obstacle detected in own lane (e.g. bicycle)
- Driving obstacle detected behind the lane delimitation (hard shoulder) with narrow lane
Function sequence for recognition of driver activity
The following situations suggest driver activity and result in suppression of any pending warning or brake intervention:
- Clearly active steering, braking or accelerating
- Cutting a tight corner
- Turn signals
- Sporty driving at high cornering speeds or with high 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 on the steering wheel angle and on the steering wheel velocity via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera.
Brakes:
The Electronic Stability Program control unit sends the status of the brake pedal via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera.
Acceleration:
The powertrain control unit sends information on the accelerator pedal position via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera.
Turn signaling:
The steering column tube module control unit reads in the switch position of the combination switch directly and sends it via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera.
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 suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit and to the stereo multifunction camera.
If the stereo multifunction camera and the Mercedes-Benz Intelligent Drive control unit detect active corner cutting, crossing of the lane markings at a large angle or a high lateral acceleration, a pending warning or brake application is also suppressed here.
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 Active Lane Keeping Assist deems the driver to be "distracted". Control interventions are evaluated by the stereo multifunction camera. The warning threshold is adjusted to match the control actuating frequency, i.e. the Active 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:
- Steering column adjustment switch (with CODE 275 (Memory package))
- Instrument cluster multifunction steering wheel button group or head unit 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 head unit sends information on the control interventions on the audio system to the stereo multifunction camera via user interface CAN, electronic ignition lock control unit, chassis FlexRay.
Control interventions on comfort functions:
The steering wheel electronics read in the operation signals on the multifunction steering wheel button groups directly and transmit them to the steering column tube module control unit over the steering wheel CAN. The steering column tube module control unit reads in the operation signals of the steering column adjustment (with code 275 (Memory Package)) directly and sends information about operating interventions on the steering column adjustment switch (with code 275 (Memory Package)) and to the multifunction steering wheel button groups over the suspension FlexRay to the mono multifunction camera.
The left front door control unit reads in the control signals of the driver-side power window and outside mirror adjustment switch group via left front door LIN and sends them to the stereo multifunction camera via interior CAN, the electronic ignition lock control unit and the suspension FlexRay.
Interior illumination control interventions:
The overhead control panel control unit reads in the operation signals of the interior lamp automatic function button and the front reading lamp buttons directly and sends them via the interior CAN, electronic ignition lock control unit and the chassis FlexRay to the stereo multifunction camera.
Additional function requirements for warning output
- Lane recognition by the stereo multifunction camera
- Vehicle speed v = 60 up to 250 km/h
- Radius of curve r > 150 m
- Exiting of lane detected (detected by stereo multifunction camera)
Function sequence for issuing warning
The stereo multifunction camera starts the warning sequence once the vehicle has driven over the lane markings (broken or solid white lines).
As of 01.06.2018:
For the haptic warning on the steering wheel, the electrical power steering control unit acts on the rack-and-pinion steering gear via the electric power steering actuator motor. The stereo multifunction camera transmits the warning request via the suspension FlexRay to the electrical power steering control unit. The intensity of the haptic warning is adapted to the vehicle speed in order to allow for the effects of the suspension at high speeds.
With code 498 (Japan version), a visual warning is also issued on the instrument cluster. The stereo multifunction camera sends the corresponding request to the instrument cluster via the chassis FlexRay, electronic ignition lock control unit and user interface CAN.
Up to 31.05.2018:
The warning is issued haptically by the steering wheel vibration motor, which is integrated into the multifunction steering wheel. The stereo multifunction camera sends the request to actuate the steering wheel vibration motor to the steering column tube module control unit via the chassis FlexRay. The steering column tube module control unit sends this request over the steering wheel CAN to the steering wheel electronics, which then actuate the steering wheel vibration motor. The steering wheel vibration motor is actuated for a period of 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 and/or turn signaling).
Up to 31.05.2018 the "Standard" operating mode suppresses a haptic warning under the following requirements:
- Turn signaling recognized (the warnings are suppressed for a certain period of time)
- Intervention of a driving safety system detected (e.g. through ESP®, Active Brake Assist with intersection function or Active Blind Spot Assist)
As of 01.06.2018 and up to 31.05.2018 with "Adaptive" operating mode selected, a haptic warning is suppressed under the follow requirements:
- Turn signaling recognized (the warnings are suppressed for a certain time period)
- Intervention of a driving safety system detected (e.g. through ESP®, Active Brake Assist with intersection function or Active Blind Spot Assist)
- Heavy acceleration (e.g. kickdown)
- Strong braking
- Rapid steering movements (e.g. during an evasive maneuver or during a rapid lane change)
- Corner cutting recognized
Following a suppression (driver activity, triggering condition not given) up to 31.05.2018 in the "Standard" operating mode a warning cannot be issued again until after approx. t = 3 s, up to 31.05.2018 in the "Adaptive" operating mode or as of 01.06.2018 only after approx. t = 5 s and after turn signaling only after t = 10 s.
By means of lane recognition and the current vehicle position, the stereo 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 stereo multifunction camera via the chassis FlexRay. 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.
Additional function requirements for active intervention by the brake system
- Lane warner ready for intervention
- No driver activity detected
- No obstacle detected within own lane
- The lane delimitation crossed is a continuous line
- The lane delimitation crossed is a broken line and oncoming traffic/parallel traffic is recognized by the radar sensor system or the stereo multifunction camera
- Lane width s = 2.6 up to 4.7 m (vehicle speed v = 60 up to 200 km/h)
- Radius of curve r > 500 m (inner radius), r > 150 m (outer radius)
- ESP® not switched to passive:
The Electronic Stability Program control unit sends the status of the ESP® via the suspension FlexRay to the stereo multifunction camera and to the Mercedes-Benz Intelligent Drive control unit.
- ESP® not in active diagnostic or roller dynamometer mode
- No autonomous brake interventions detected (e.g. by ESP®, Active Brake Assist with intersection function or Active Blind Spot Assist)
- Tire pressure of all wheels within the tolerance range (no run-flat mode active) (with code 475 (Tire pressure monitoring system (Premium)) or code 477 (Tire pressure loss warning system)):
On vehicles with code 475 (Tire pressure monitoring system (Premium)), the tire pressure monitoring system control unit sends the information on the respective tire pressure to the stereo multifunction camera and to the Mercedes-Benz Intelligent Drive control unit via user interface CAN, electronic ignition lock control unit and suspension FlexRay.
On vehicles with CODE 477 (Tire pressure loss warning), the tire pressure is determined based on the rolling circumference. The tire pressure loss warning (RDW) system is functionally integrated in the Electronic Stability Program control unit. The Electronic Stability Program control unit sends the information on the tire pressure via the suspension FlexRay to the stereo multifunction camera and to the Mercedes-Benz Intelligent Drive control unit.
- No trailer operation recognized (with code 550 (Trailer hitch)):
If a trailer is detected, the trailer recognition control unit (with code 550 (Trailer hitch)) sends the "trailer detected" status via the interior CAN, electronic ignition lock control unit and suspension FlexRay to the stereo multifunction camera and to the Mercedes-Benz Intelligent Drive control unit.
- Approval issued for active intervention by the brake system for yawing moment interface
The yawing-moment interface is integrated into the Electronic Stability Program control unit and it sends out a status signal to enable a course-correcting braking torque.
Function sequence for active intervention by the brake system
If the vehicle, for example, crosses over a continuous line on the right side of the vehicle, the Mercedes-Benz Intelligent Drive control unit decides whether and with which intensity a course-correcting brake application is to take place.
When the stereo multifunction camera does not detect any driver activity or any obstacles in the vehicle surroundings, the Mercedes-Benz Intelligent Drive control unit enables brake application.
The Mercedes-Benz Intelligent Drive control unit sends the request for wheel-specific (active) braking on the wheel side opposite the line via the suspension FlexRay to the Electronic Stability Program control unit. The Electronic Stability Program control unit implements this request and actuates the traction system hydraulic unit accordingly. The vehicle is "guided back" into the lane. At the same time as the wheel-specific intervention by the brake system, the driver is visually notified of this activity.
The stereo multifunction camera sends the corresponding request to the instrument cluster via the chassis FlexRay, electronic ignition lock control unit and user interface CAN. The brake intervention is canceled immediately as soon as driver activity is detected (e.g. if the driver steers against the brake intervention (overrides the brake intervention)) or if the above function requirements are no longer given.
The brake intervention is canceled immediately as soon as driver activity is detected (e.g. if the driver steers against the brake intervention (overrides the brake intervention)) or if the above function requirements are no longer given.
In the event of brake intervention, a visual warning message is shown in the multifunction display of the instrument cluster. The stereo multifunction camera sends the request to output a warning to the instrument cluster via the chassis FlexRay, electronic ignition lock control unit and user interface CAN.
Appearance of warning indication
| Electrical function schematic for Active Lane Keeping Assist | PE54.71-P-2053-97SEB | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998LFM |