Active Brake Assist With Cross-Traffic Function, Function - GF30.30-P-3341FG
Model 213
up to model year 2021
with code 23P (Drive package)
Function requirements, general
- No undervoltage or overvoltage
- Active Brake Assist switched on with a intersection function in the head unit menu:
The head unit transmits the status of the Active Brake Assist with cross-traffic function via the user interface CAN, electronic ignition lock control unit and suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
- Engine running or drivetrain operational:
The CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or "Drivetrain operational" signal to the Mercedes-Benz Intelligent Drive control unit via drive CAN, powertrain control unit and suspension FlexRay.
- Gear range "N" (only the distance warning active) or "D" engaged (vehicle not in backward movement):
The fully integrated transmission control, control unit sends information about the selected drive range via drive CAN, powertrain control unit and suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
In the gear range "N" only the distance warning is active.
- Soiling and function test of the short and long-range radar sensor: Object recognition (e.g. vehicle moving directly ahead) via the radar sensor system is based on the radar measuring procedure. The short and long range radar sensor performs a soiling and function test to secure its perfect function after every 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, the Active Brake Assist cannot be activated.
The short and long range radar, when functioning properly, transmits the status "Radar sensor system operational" via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
- Stereo multifunction camera soiling and function test:
The stereo multifunction camera 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, the Active Brake Assist cannot be activated. The stereo multifunction camera sends the status via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
- No tight curve
- No active ESP® intervention recognized (vehicle not in sliding movement):
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 transmits these via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
- Vehicle speed from 7 to 250 km/h:
The vehicle speed is calculated from the wheel speeds, the direction of travel is defined by the wheel rotation direction. The Electronic Stability Program control unit sends the respective signals to the Mercedes-Benz Intelligent Drive control unit via the suspension FlexRay.
- Driver and front passenger belt buckle latched (if front passenger detected by seat recognition) and front passenger door closed
Active Brake Assist with intersection function, general points
The Active Brake Assist with intersection function assesses the traffic situation in front of the vehicle and continuously determines the risk potential for a rear-end collision or for a collision with a vehicle intersection its path. In critical accident situations Active Brake Assist with intersection function initiates appropriate measures geared towards avoiding a collision or - at the least - reducing the possible consequences of a collision. Furthermore, there is a distance warning function contained therein which advises the driver about a vehicle driving immediately ahead which is too close. An optical and acoustic warning is issued before any possible collisions with vehicles or stationary obstacles on the vehicle's own lane.
The Active Brake Assist with intersection function can also provide support in the case of possible collisions with intersection traffic at intersections. The pedestrian detection can prevent a collision with pedestrians or reduce the severity of the impact. If the driver does not actuate the brake hard enough in a hazardous situation, the situation-related brake servo assistance automatically increases the brake pressure to ensure effective emergency braking, if necessary up to emergency braking. The brake application which is metered according to the situation is also makes the greatest possible braking distance available for the traffic to the rear.
In the vehicle speed range from 7 to 250 km/h, the Active Brake Assist with cross-traffic function is activated in a possible danger situation. In the case of stationary obstacles, the Active Brake Assist with cross-traffic function is only activated if the vehicle's own speed is max. 100 km/h. For pedestrians and crossing vehicles, the maximum vehicle speed may be 72 km/h. It is controlled by the Mercedes-Benz Intelligent Drive control unit which actively intervenes in the brake system.
The warning output type of the Active Brake Assist with cross-traffic function can be selected and set via the operating level in the head unit. For navigation in the operating menu the following options are available:
- Except code 446 (Touchpad only), the navigation in the operating menu can be realized with the Audio/COMAND control panel. The Audio/COMAND control panel sends the control signals via telematics CAN to the head unit.
- With code 446 (Touchpad only) or code 448 (Touchpad), the navigation in the operating menu can be realized with the touchpad. The touchpad sends the operation signals over the telematics CAN to the head unit.
- With code 531 (COMAND APS), the navigation in the operating menu can be realized via the voice control. The head unit evaluates for this purpose the voice commands via the driver's hands-free system microphone.
- The navigation in the operating menu can also be realized with the head unit finger navigation pad and the "Back" button on the steering wheel. The steering wheel electronics reads in the operation signals of the head unit finger navigation pad and the "Back" button and transmits these via the steering LIN (up to model year 2019) or steering wheel CAN (as of model year 2019), steering column tube module control unit, suspension FlexRay, electronic ignition lock control unit and user interface CAN to the head unit.
- The operating menu can be called up over vehicle button the upper control panel control unit (with code 246 (Analog clock)). The upper control panel control unit reads in the "Vehicle" button status and transmits this via the LCP-LIN, Audio/COMAND control panel (except code 446 (Touchpad only)) or touchpad (with code 446 (Touchpad only)) and telematics CAN to the head unit.
The head unit transmits the status of the Active Brake Assist with cross-traffic function via the user interface CAN, electronic ignition lock control unit and suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
The driver can select the following operating modes:
- CENTER
In the as-delivered state the Active Brake Assist with intersection function is in the operating mode center. When the Active Brake Assist with intersection function is switched off, the operating mode center is automatically active after a renewed ignition cycle.
- Retarded
The selection is retained the next time the engine is started.
- Advanced
The selection is retained the next time the engine is started.
Illustration of the principle of Active Brake Assist with intersection function with one stationary or significantly slower vehicle on one's own lane
After autonomous emergency braking up to vehicle standstill the vehicle remains stalled.
The Active Brake Assist with intersection function consists of the following subfunctions:
- Distance warning
- Brake force boosting
- Autonomous brake application
- Autonomous brake application for pedestrians
- End-of-tailback emergency braking function
Distance warning
Detection ranges for radar sensor system/stereo multifunction camera, shown on model 213
Static distance warning (without code 494 (USA version) or without code 460 (Canada version)):
Output of the static distance warning takes place purely optically. The static distance warning (at a vehicle speed from 30 km/h) is triggered, if the time interval of the vehicle to the vehicle in front falls below a threshold for a certain period (e. g. in moving traffic). The DISTRONIC warning lamp lights up in the IC.
The Mercedes-Benz Intelligent Drive control unit sends the corresponding request via the suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the instrument cluster.
Collision critical distance warning:
Output of the collision-critical distance warning takes place optically and acoustically.
If at a vehicle speed from 7 to 250 km/h a moving or stationary obstacle or at a vehicle speed from 7 to 72 km/h a crossing obstacle is classified as accident critical in the detection range of the radar sensor system or the stereo multifunction camera, the DISTRONIC warning lamp lights up and the instrument cluster speaker also outputs an intermittent warning tone.
The Mercedes-Benz Intelligent Drive control unit sends the corresponding request to actuate the instrument cluster speaker via the suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the instrument cluster. The instrument cluster directly actuates the instrument cluster speaker. The warning is switched off again automatically one the situation is no longer critical.
Optical warning messages in instrument cluster
This is shown inversely on the IC, i. e. the distance warning readiness indicator is hidden when the distance warning function is active. If the distance warning function is deactivated, the distance warning readiness indicator and the "OFF" lettering are shown.
Brake force boosting
If the driver then reacts to the collision-critical distance warning with emergency braking, the Active Brake Assist with intersection function provides support for the best possible utilization of the braking distance to the obstacle. The brake force boosting is available in a vehicle speed range from 7 to 250 km/h.
Maximum full-stop braking is defined over the current vehicle deceleration and the change in wheel speed.
The change in the wheel speeds (deceleration of the vehicle) tells the Mercedes-Benz Intelligent Drive control unit that the driver wishes to brake. The Electronic Stability Program control unit reads in the signals from the rpm sensors directly and sends this information via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
The Mercedes-Benz Intelligent Drive control unit uses the data from the short and long range radar sensor and the stereo multifunction camera, calculates the required braking torque and transmits the request via the suspension FlexRay to the Electronic Stability Program control unit which reacts by directly activating the traction system hydraulic unit.
If a collision is unavoidable, occupant protection measures are taken in addition to intervention by the brake system.
If there is no actuation or the intensity of the brake pedal actuation by the driver significantly decreases, the driver clearly actuates the accelerator pedal or avoids the collision, the brake force boosting on the driver braking is reduced or canceled.
The brake force boosting can react up to a ground speed of approx. 100 km/h to stationary obstacles and up to approx. 72 km/h to crossing obstacles.
Additional function requirements for autonomous braking
- Vehicle speed: approx. 7 to 250 km/h (for moving obstacles), approx. 7 to 100 km/h (for stationary obstacles) or approx. 7 to 72 km/h (for crossing obstacles)
- Driver seat belt fastened
Autonomous brake application
If the driver does not react to the collision-critical warning, the Active Brake Assist with intersection function initiates autonomous brake application. To do this, the Mercedes-Benz Intelligent Drive control unit calculates the corresponding braking torque while taking account of the following driving dynamics input factors:
- Speed difference relative to the vehicle or obstacle j
- Distance from vehicle or obstacle
The Mercedes-Benz Intelligent Drive control unit transmits the respective request to increase the braking torque and to reduce the engine torque via the suspension FlexRay to the Electronic Stability Program control unit, which reacts by directly actuating the traction system hydraulic unit and sending the request for engine torque reduction via the suspension FlexRay, powertrain control unit and drive CAN to the CDI control unit or the ME-SFI [ME] control unit. If the driver reacts to the autonomous brake application with a maximum full-stop braking maneuver, selective brake force boosting provides the driver with support for the best possible utilization of the braking distance to the obstacle.
Maximum full-stop braking is defined over the current vehicle deceleration and the change in wheel speed.
Emergency braking is only triggered if the driver and the front passenger have their seat belts on.
Parallel to this the Electronic Stability Program control unit evaluates the currently requested braking torque and initiates appropriate measures for OCCUP.PROT.SYS, if necessary.
Additional function requirements for autonomous braking to avoid pedestrians
- Vehicle speed: approx. 7 to 72 km/h
- Driver seat belt fastened
Autonomous brake application for pedestrians
If a pedestrian is detected by the radar sensor system or by the stereo multifunction camera within a critical distance in the vehicle path, the Mercedes-Benz Intelligent Drive control unit issues a collision-critical distance warning.
Details in this connection can be found in the chapter "Distance warning".
If the driver then reacts to the collision-critical distance warning with emergency braking, the Active Brake Assist with intersection function provides support for the best possible utilization of the braking distance to the obstacle.
Maximum full-stop braking is defined over the current vehicle deceleration and the change in wheel speed. The change in the wheel speeds (deceleration of the vehicle) tells the Mercedes-Benz Intelligent Drive control unit that the driver wishes to brake. The Electronic Stability Program control unit reads in the signals from the rpm sensors directly and sends this information via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
The Mercedes-Benz Intelligent Drive control unit uses the data from the short and long range radar sensor and the stereo multifunction camera, calculates the required braking torque and transmits the request via the suspension FlexRay to the Electronic Stability Program control unit which reacts by directly activating the traction system hydraulic unit.
If the driver does not react to the collision-critical warning, the Active Brake Assist with intersection function initiates autonomous brake application and reduction of the engine torque. To do this, the Mercedes-Benz Intelligent Drive control unit calculates the corresponding braking torque while taking account of the following driving dynamics input factors:
- Speed differential to the pedestrian
- Distance to the pedestrian
The Mercedes-Benz Intelligent Drive control unit transmits the relevant request to increase the braking torque and reduce the engine torque via the suspension FlexRay to the Electronic Stability Program control unit. The Electronic Stability Program control unit then actuates the traction system hydraulic unit and transmits the engine torque reduction request via the suspension FlexRay, powertrain control unit and drive CAN to the CDI control unit or the ME-SFI [ME] control unit. If the driver reacts to the autonomous brake application with a maximum full-stop braking maneuver, selective brake force boosting provides the driver with support for the best possible utilization of the braking distance to the obstacle.
Maximum full-stop braking is defined over the current vehicle deceleration and the change in wheel speed.
Emergency braking is only triggered if the driver and the front passenger have their seat belts on.
Parallel to this the Electronic Stability Program control unit evaluates the currently requested braking torque and initiates appropriate measures for OCCUP.PROT.SYS, if necessary.
Additional function requirements for the traffic jam emergency braking function
- Vehicle speed: approx. 7 to 130 km/h
- Driver seat belt fastened
End-of-tailback emergency braking function
If the radar sensor system and the stereo multifunction camera detect a traffic jam scenario without any option to avoid it (e. g. due to vehicles on the neighboring lanes or due to guardrails), the Mercedes-Benz Intelligent Drive control unit issues a static or collision-critical distance warning.
Details in this connection can be found in the chapter "Distance warning".
Furthermore the Active Brake Assist with intersection function initiates early emergency braking and reduction of the engine torque. For this purpose, the Mercedes-Benz Intelligent Drive control unit calculates - taking into account the driving dynamic input factors - the relevant braking torque and transmits the request to increase the braking torque and reduce the engine torque via the suspension FlexRay to the Electronic Stability Program control unit. The Electronic Stability Program control unit then actuates the traction system hydraulic unit and transmits the engine torque reduction request via the suspension FlexRay, powertrain control unit and drive CAN to the CDI control unit or the ME-SFI [ME] control unit.
Parallel to this the Electronic Stability Program control unit evaluates the currently requested braking torque and initiates appropriate measures for OCCUP.PROT.SYS, if necessary.
| Electrical function schematic of Active Brake Assist with cross-traffic function | PE30.30-P-2073-97DBA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998FG |