Active Blind Spot Assist, Function - GF54.71-P-0006FG
Model 213 up to model year 2021 with code 237 (Active Blind Spot Assist) up to model year 2019
As of model year 2019
Function requirements, general
- No undervoltage or overvoltage
- Active Blind Spot Assist activated through head unit
- Soiling and function test on radar sensor system completed successfully:
Object detection (e.g. vehicle directly ahead) through the radar
- Engine running or drive train operational
Sensor system is based on the radar measuring procedure. The close and long range radar sensor and the rear outer bumper radar sensors perform a soiling and function test after each engine start to ensure that they are functioning correctly. The function test requires an object (long range only) in the detection area. If a malfunction is established or if there are no objects in the detection area, the Active Blind Spot Assist cannot be activated. The Mercedes-Benz Intelligent Drive control unit receives the signals of the rear outer bumper radar sensors over the rear radar CAN and sends them over the suspension FlexRay to the close and long range radar sensor. The short and long-range radar sensor evaluates them in combination with its own signals and, when all the radar sensors are functioning correctly, sends the "Radar sensor system operational" status over the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
- Vehicle moving forward
- Vehicle speed above 10 km/h
- No trailer operation (with code 550 (Trailer hitch))
Active Blind Spot Assist, general
The Active Blind Spot Assist monitors the rear and side areas of the vehicle using short-range radar and, if necessary, informs the driver that an intentional lane change (turn signal active) is not recommended at this time. Active Blind Spot Assist acts - in a broader sense - as an extension of the outside mirrors. It does not release the driver of his/her obligation to perform lane changes safely on his/her own responsibility.
Active Blind Spot Assist is activated through the head unit. The following options are available for navigating in the control menu:
- Except code 446 (Touchpad only), the navigation is operated in the control menu using the Audio/COMMAND control panel. The Audio/COMMAND control panel sends the control signals via telematics CAN to the head unit.
- With code 446 (Touchpad only) or code 448 (Touchpad), the navigation can be operated in the control panel with the touchpad. The touchpad sends the operation signals over the telematics CAN to the head unit.
- With code 531 (COMMAND APS), the navigation can be operated in the control menu using voice control. The head unit evaluates the voice commands from the driver hands-free system microphone.
- The navigation in the control menu can also be operated using 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 sends them over the steering LIN (up to model year 2019) or the steering wheel CAN (as of model year 2019), steering column tube module control unit, suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the head unit.
- With code 246 (Analog clock), the control menu can be called up with the Vehicle button in the upper control panel control unit. The upper control panel control unit reads in the status of the vehicle button and sends this over the LCP-LIN, Audio/COMMAND control panel (except code 446 (Touchpad only)) or touchpad (with code 446 (Touchpad only)) and the telematics CAN to the head unit.
The head unit sends the status of the Active Blind Spot Assist over the user interface CAN, electronic ignition lock control unit and the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
The visual warning output takes place via the following components:
- Left blind spot assistant warning indicator
- Right blind spot assistant warning indicator
When the Blind Spot Assist menu is selected, a warning message (vehicle with Active Blind Spot Assist and vehicle detected in the right or left blind spot) is shown in the instrument cluster in addition to the warning indications in the outside mirrors.
The acoustic warning is output over the instrument cluster speaker that is directly actuated by the instrument cluster. The readiness indicator is shown on the instrument cluster. Active Blind Spot Assist can additionally perform brake system interventions to correct the course, taking the surroundings of the vehicle into account. The active interventions by the brake system are performed on specific wheels and have a course-correcting effect on the vehicle. If a risk of collision is detected with vehicles that are in the blind spot, then an accident can be avoided or the consequences of the accident lessened.
The area that cannot be observed via the outside mirrors is monitored by the following components:
- Right outer rear bumper radar sensor
- Left outer rear bumper radar sensor
The course-correcting intervention is dependent on the road space in front of the vehicle being monitored to avoid any collisions with other road user because of any change in direction. Monitoring of the road in front of the vehicle is performed by the following components:
- Short and long-range radar sensor
- Stereo multifunction camera (only with availability)
The Mercedes-Benz Intelligent Drive control unit reads in the signals from the left and right outer rear bumper radar sensors over the rear radar CAN, the signals from the short and long-range radar sensor and stereo multifunction camera over the suspension FlexRay and evaluates them.
Illustration showing principle of Blind Spot Assist, shown on model 213.0
The following information is evaluated by the Mercedes-Benz Intelligent Drive control unit and other control units:
- Terminal status of terminal 15
- Active Blind Spot Assist status
- Engine running or drive train operational
- Vehicle moving forward
- Vehicle speed
- Steering wheel angle and steering wheel velocity
- Driving stage engaged
- Brake status
- Trailer operation status (with code 550 (Trailer hitch))
Status of circuit 15:
The electronic ignition lock control unit sends the status of circuit 15 over the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Active Blind Spot Assist status:
The head unit sends the status of the Active Blind Spot Assist over the user interface CAN, electronic ignition lock control unit and the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Engine running or drive train operational:
The CDI control unit or the ME-SFI 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.
Vehicle in forward movement, vehicle speed:
Forward movement is defined via the wheel rotation direction. The vehicle speed is calculated from the wheel speed. The Electronic Stability Program control unit sends this information to the Mercedes- Benz Intelligent Drive control unit over the suspension FlexRay. The Mercedes-Benz Intelligent Drive control unit uses it to calculate the vehicle speed and define the direction of travel.
Steering wheel angle and steering wheel velocity:
The steering wheel angle sensor measures the steering wheel angle and the steering wheel velocity. The steering column tube module control unit directly reads in the signals of the steering wheel angle sensor and transmits information on the steering wheel angle and the steering wheel velocity via the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Engaged drive position:
The fully integrated transmission control unit transmits information about the selected drive range over the drive CAN, the powertrain control unit and the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Brake status:
The Electronic Stability Program control unit sends the status of the brake over the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Trailer recognition (with code 550 (Trailer hitch)):
When a trailer is detected, the trailer recognition control unit sends the "Trailer detected" status to the Mercedes-Benz Intelligent Drive control unit over the interior CAN, electronic ignition lock control unit and suspension FlexRay.
The Active Blind Spot Assist consists of the following subfunctions:
- Measuring method
- System and warning messages
- Active brake application
Measuring method
Vehicles are detected based on the radar measuring method and the video data from the stereo multifunction camera.
The radar sensors emit bundled electromagnetic waves as "primary signals". If these impact on an object they are then reflected by it and received by the radar sensor as a secondary signal. These signals are used to calculate the distance and the speed of the detected object as well as its angle relative to the vehicle.
The monitored area is designed to be flexible and is controlled as a function of the vehicle speed. The Mercedes-Benz Intelligent Drive control unit reads in the signals of the rear bumper radar sensors over the rear radar CAN and the signals of the short and long-range radar sensors over the suspension FlexRay and evaluates them. The stereo multifunction camera consists of two high-resolution mono cameras and an integrated control unit. The laterally offset location of the two mono cameras creates a difference in perspective (parallax displacement) between the left and right optical path.
The integrated control unit evaluates image data from the two mono cameras, processes it and sends the corresponding data over the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
System and warning messages
When circuit 15 is switched on, the Blind Spot Assist warning indicators light up in red, until the CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or "Drive train operational" signal. Additionally, when the "Assistance" menu is switched on in the instrument cluster, the readiness of the Active Blind Spot Assist is shown in the instrument cluster (gray radar waves appear spreading towards the rear next to the vehicle). If system errors are detected, a corresponding fault message appears instead of the readiness indicator.
The Mercedes-Benz Intelligent Drive control unit sends the request to issue system and fault messages as well as warnings over the suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the instrument cluster. The instrument cluster actuates the instrument cluster speaker to issuing warning tones. The Mercedes-Benz Intelligent Drive control unit also sends the request to issue warnings over the suspension FlexRay, electronic ignition lock control unit and the interior CAN to the respective front door control unit, which then actuates the corresponding Blind Spot Assist warning display.
If, at a speed above 12 km/h, a vehicle is located in the detection range of the radar sensor system, the driver is warned by the Blind Spot Assist warning display lighting up in red in the outside mirror on the side of the vehicle on which the vehicle is in the blind spot.
Additionally, a warning is shown in the multifunction display of the instrument cluster. Predictive warnings of overtaking vehicles are given before they even enter the blind spot, within the framework of the system limitations. If the driver attempts to initiate a lane change despite the Blind Spot Assist warning display being on, and signals this by using the combination switch (operating turn signal indicator), a single dual warning tone is also issued through the instrument cluster speaker. The Blind Spot Assist warning indicator flashes on and off. If the vehicle leaves the detection range of the radar sensor system, the red flashing Blind Spot Assist warning indicator is switched off.
The steering column tube module control unit reads in the switch position of the combination switch directly, and sends it over the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Blind Spot Assist readiness indicator
The function status "Off" display is shown when the Active Blind Spot Assist is deactivated and in the event of a fault.
When the Active Blind Spot Assist is switched on via the "Assistance" menu in the instrument cluster, function status "On" is displayed. The Active Blind Spot Assist is activated, but not ready to issue a warning because additional function requirements such as a vehicle speed of more than 12 km/h are not met. When the function status "Operational" is issued by instrument cluster, the Active Blind Spot Assist is switched on and all additional function requirements are met.
The Active Blind Spot Assist is ready to issue a warning.
Blind Spot Assist warning display in instrument cluster, shown on model 213.0
Blind Spot Assist warning indicator, shown on left outside mirror
The following table contains the requirements for displaying system readiness and for showing the visual warning messages:
| Operating state | Blind Spot Assist warning indication in the outside mirror "Off" | Blind Spot Assist readiness indicator in the instrument cluster, function status "On" | Blind Spot Assist readiness indicator in the instrument cluster, function status "Operational" | Blind Spot Assist warning indication in the outside mirror, red on | Blind Spot Assist warning indication in the outside mirror, flashing red |
|---|---|---|---|---|---|
| Circuit 15 OFF | x | - | - | - | - |
| Terminal 15 ON | - | - | - | x | - |
| Engine running or drive train operational | x | - | - | - | - |
| Active Blind Spot Assist activated via the instrument cluster | - | x | - | - | - |
| Vehicle accelerates, vehicle speed v ≥ 8 km/h | x | - | x | - | - |
| Vehicle decelerates, vehicle speed v < 25 km/h | x | x | - | - | - |
| Trailer recognized (with code 550 (Trailer hitch)) | x | - | - | - | - |
| Drive position "R" engaged | x | x | - | - | - |
| Vehicle recognized in blind spot | - | - | x | x | - |
| Turn signal active, vehicle detected in blind spot | - | - | x | - | x |
| Course-correcting intervention by the brake system active | x | ||||
| Fault detected | x | - | - | - | - |
Gear range "R" engaged:
Gear range "R" is engaged through the fully integrated transmission control unit. The fully integrated transmission control unit then sends the "Gear range R engaged" status to the electronic ignition lock control unit over the drive train CAN, drivetrain control unit and suspension FlexRay. The electronic ignition lock control unit generates a "Reverse gear engaged" status and sends this over the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Additional function requirements for active intervention by the brake system
- Electronic Stability Program (ESP®) not switched to passive mode: The Electronic Stability Program control unit sends the ESP® status over the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
- ESP® not in active diagnostic or roller dynamometer mode
- No ESP® control intervention function
- Anti-lock Brake System (ABS), anti-slip control (ASR), Active Brake Assist with cross-traffic function, ESP®, electronic traction system (ETS) or Trailer Stability Assist inactive
- Vehicle speed above 30 and under 200 km/h
- Approval issued for active intervention by the brake system for yawing moment interface
The yawing moment interface is integrated in the Electronic Stability Program control unit and internally issues a signal to enable a course-correcting braking torque.
Active brake application
If the Mercedes-Benz Intelligent Drive control unit detects the threat of an imminent side collision with a vehicle in the blind spot, in particular, during a lane change, a course-correcting brake application is requested. The Mercedes-Benz Intelligent Drive control unit sends the corresponding request to the Electronic Stability Program control unit over the suspension FlexRay. The Electronic Stability Program control unit then selectively brakes individual wheels and moves the vehicle back onto a collision-free course using the traction system hydraulic unit.
If, during an intervention by the brake system, the driver steers opposite to the intervention by the brake system (i.e. overrides the intervention by the brake system) or if the vehicle is accelerated, the intervention by the brake system is immediately canceled. The driver assistance systems or driving safety system ASR, Active Brake Assist with cross-traffic function, ESP® and ETS have a higher priority when compared with the Active Blind Spot Assist, and they can cancel an active brake application.
Course-correcting interventions by the brake system are always suppressed, when one of the following conditions occurs:
- Faster or larger pressure loss in a tire: On vehicles with CODE 475 (Tire pressure monitor), the respective tire pressure is evaluated by the tire pressure monitor control unit. The tire pressure monitoring system control unit sends information on the respective tire pressure to the Mercedes-Benz Intelligent Drive control unit over the user interface CAN, electronic ignition lock control unit and suspension FlexRay. On vehicles with CODE 477 (Tire pressure loss warning) (RDW), the tire pressure is determined based on the rolling circumference. The tire pressure loss warning system is functionally integrated into the Electronic Stability Program control unit, which sends the information on tire pressure over the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
- Vehicle collision hazard with another vehicle or obstacle
- Strong vehicle acceleration or strong deceleration in longitudinal direction as well as strong lateral acceleration: The acceleration forces are detected by the acceleration sensor integrated into the supplemental restraint system control unit. The supplemental restraint system control unit sends the acceleration force values over the vehicle dynamics CAN, Electronic Stability Program control unit and suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
- Course correcting steering interventions by driver or change in specified torque through operation of the accelerator pedal: The CDI control unit or the ME-SFI control unit transmits information about the accelerator pedal position to the Mercedes Benz Intelligent Drive control unit over the drive CAN, powertrain control unit and the suspension FlexRay.
| Electrical function schematic, Active Blind Spot Assist | PE54.71-P-2055-97DBA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998FG |