Part 1
GF54.71-P-0003CE Blind Spot Assist, Function
MODEL 204.0 /2
- with CODE (234) Blind Spot Assist
- with CODE (237) Active Blind Spot Assist as of model year 2012 /YoM 11 model refinement package
MODEL 204.3
- with CODE (234) Blind Spot Assist
- with CODE (237) Active Blind Spot Assist
Vehicles with code (234) Blind Spot Assist
A1 Instrument cluster
A1h1 Warning buzzer
A1p13 Multifunction display
A2 Radio (with code (523) MB Audio 20 radio or code (510) Audio 20 with CD changer)
A2/30 Navigation module (with code (509) Navigation box)
A2/30-1 Cradle for navigation module (with code (508) Navigation box preinstallation or code (509) Navigation box)
A28/11 Multifunction antenna
A40/3 COMAND controller unit (with code (512) COMAND APS incl. DVD changer or code (527) COMAND APS with single DVD drive (with navigation))
B29/4 Left rear bumper intelligent radar sensor
B29/5 Right rear bumper intelligent radar sensor
L6/1 Left front axle speed sensor
L6/2 Right front axle speed sensor
L6/3 Left rear axle speed sensor
L6/4 Right rear axle speed sensor
M21/1 Left outside mirror
M21/1e2 Left Blind Spot Assist readiness and warning indicator
M21/2 Right outside mirror
M21/2e2 Right Blind Spot Assist readiness and warning indicator
N3/9 CDI control unit (with diesel engine)
N3/10 ME-SFI [ME] control unit (with gasoline engine)
N10/1 Front SAM control unit with fuse and relay module
N28/1 Trailer recognition control unit (with code (550) Trailer hitch)
N30/4 Electronic Stability Program control unit
N69/1 Left front door control unit
N69/2 Right front door control unit
N73 Electronic ignition switch control unit
N80 Steering column module control unit
S4 Combination switch
CAN A Telematics CAN
CAN B Interior CAN
CAN E Chassis CAN
CAN G Front end CAN
Vehicles with code (237) Active Blind Spot Assist
A1 Instrument cluster
A1h1 Warning buzzer
A1p13 Multifunction display
A2 Radio (with code (523) MB Audio 20 radio or code (510) Audio 20 with CD changer)
A2/30 Navigation module (with code (509) Navigation box)
A2/30-1 Cradle for navigation module (with code (508) Navigation box preinstallation or code (509) Navigation box)
A7/3 Traction system hydraulic unit
A28/11 Multifunction antenna
A40/3 COMAND controller unit (with code (512) COMAND APS incl. DVD changer or code (527) COMAND APS with single DVD drive (with navigation))
A89 DISTRONIC electric controller unit
B24/15 Yaw rate, lateral and longitudinal acceleration sensor
B29/2 DISTRONIC sensor (DTR) / left front bumper
B29/3 DISTRONIC sensor (DTR) / right front bumper
B29/6 Left rear bumper radar sensor
B29/7 Right rear bumper radar sensor
L6/1 Left front axle speed sensor
L6/2 Right front axle speed sensor
L6/3 Left rear axle speed sensor
L6/4 Right rear axle speed sensor
M21/1 Left outside mirror
M21/1e2 Left Blind Spot Assist readiness and warning indicator
M21/2 Right outside mirror
M21/2e2 Right Blind Spot Assist readiness and warning indicator
N3/9 CDI control unit (with diesel engine)
N3/10 ME-SFI [ME] control unit (with gasoline engine)
N10/1 Front SAM control unit with fuse and relay module
N15/3 Electronic transmission control control unit (with transmission 722.6)
N28/1 Trailer recognition control unit (with code (550) Trailer hitch)
N30/4 Electronic Stability Program control unit
N49 Steering angle sensor
N62/2 Video and radar sensor system control unit
N69/1 Left front door control unit
N69/2 Right front door control unit
N73 Electronic ignition switch control unit
N80 Steering column module control unit
S4 Combination switch
Y3/8n4 Fully integrated transmission control unit (with transmission 722.9)
CAN A Telematics CAN
CAN B Interior CAN
CAN C Drive train CAN
CAN E Chassis CAN
CAN H Vehicle dynamics CAN
CAN S Sensor CAN
Function requirements, general
^ No undervoltage or overvoltage
^ Function of "Blind Spot Assist" in "Assist" menu activated in IC (A1)
^ Navigation module plugged in (with code (508) Navigation box preinstallation or code (509) Navigation box)
^ Radar sensor system not switched off
^ Engine running or drivetrain operational
^ Vehicle moving forward
^ Vehicle speed: v = greater than or equal to 30 to 250 km/h
^ No trailer operation (with code (550) Trailer hitch)
Blind Spot Assist, general
The Blind Spot Assist system monitors the rear and side areas of the systems vehicle using a short range radar and, if necessary, informs the driver that an intentional lane change (turn signal set) is not recommended at a given point in time. In the wider sense the Blind Spot Assist serves as an extension of the rearview mirror; under no circumstances is the driver relieved of his responsibility of safely carrying out the lane change as his own responsibility.
In the left outside mirror and in the right outside mirror, a visual indicator indicates when the system is active and when a critical situation occurs during a lane change (i.e. a vehicle is in the"blind spot"). In addition, an acoustic warning can also be given.
The visual warning output takes place via the following components:
- Left Blind Spot Assist readiness and warning indicator
- Right Blind Spot Assist readiness and warning indicator
The acoustic warning is output via the warning buzzer in the instrument cluster.
The from SAM control unit is the central interface for data exchange between the different CAN bus systems (Gateway).
A distinction is currently made between the following Blind Spot Assist variants:
- Blind Spot Assist (with code (234) Blind Spot Assist)
- Active Blind Spot Assist (with code (237) Active Blind Spot Assist)
Blind Spot Assist:
The area which cannot be observed on the outside mirror and inside rearview mirror (A67) is monitored by the following components:
- Left rear bumper intelligent radar sensor
- Right rear bumper intelligent radar sensor
All relevant data are evaluated by the intelligent radar sensors, whereby the right intelligent radar sensor request the warning output.
The intelligent radar sensors operate according to the "master- slave" principle The "master" or "slave" function can be determined by means of the connector coding. The "master function" is defined for the right intelligent radar sensor. In other words, the left intelligent radar sensor sends its requests to output warning and readiness messages over the front end CAN to the right intelligent radar sensor, which evaluates the information of both intelligent radar sensors, and then forwards corresponding requests over the front end CAN to the front SAM control unit.
Active Blind Spot Assist:
Active Blind Spot Assist builds upon the functionality of Blind Spot Assist. Active Blind Spot Assist can additionally perform course- correcting brake system interventions taking the surroundings of the vehicle with the system into account.
Active interventions by the brake system are conducted on a wheel-specific basis and exert a course-correcting influence on the vehicle with the system.
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 which cannot be observed via the outside mirror and inside rearview mirror is monitored by the following components:
- Left rear bumper radar sensor
- Right 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 (incl. oncoming traffic) because of any change in direction.
Monitoring of the road in front of the vehicle is performed by the following components:
- DISTRONIC controller unit
- DISTRONIC sensor (DTR) / left front bumper
- DISTRONIC sensor (DTR) / right front bumper
The signals of the front bumper DISTRONIC (DTR) sensors and the signals from the rear bumper radar sensors are sent to the video and radar sensor system control unit over the sensor CAN.
The signals of the DISTRONIC electric controller unit are received by the video and radar sensor system control unit over the vehicle dynamics CAN.
All relevant data are evaluated by the video and radar sensor system control unit.
Illustration of the Blind Spot Assist principle
A Lane with vehicle in blind spot during passing maneuver
B Lane with systems vehicle
t1 Vehicle moves into blind spot
t2 Vehicle in blind spot detected, acoustic and visual warning messages issued
t3 Initiation of course-correcting intervention by the brake system (with code (237) Active Blind Spot Assist)
t4 Course-correcting intervention by the brake system completed, collision avoided (with code (237) Active Blind Spot Assist)
The following information is evaluated by the Blind Spot Assist:
The status of the "Blind Spot Assist" function (switched on/off) is sent by the instrument cluster over the chassis CAN).
- Status of function "Blind Spot Assist"
- Engine running or drivetrain operational
- Vehicle moving forward
- Vehicle speed
- Trailer recognition status (with code (550) Trailer hitch)
- Status of shift stage (with code (237) Active Blind Spot Assist)
- Status of service brake (with code (237) Active Blind Spot Assist)
The status of the "Blind Spot Assist" function (switched on/off) is sent by the instrument cluster over the chassis CAN).
The "engine running" and "drivetrain operational" states are sent by the CDI control unit or the ME-SFI control unit via the chassis CAN.
The forward movement is defined via the wheel rotation direction and the vehicle speed via the wheel speed.
The wheel rotation direction and wheel speed are recorded by the following components:
- Left front axle speed sensor
- Right front axle speed sensor
- Left rear axle speed sensor
- Right rear axle speed sensor
The wheel rotation direction is determined dependent on the drive variants. Detailed information on the function can be found in the separate description "Adaptive Brake (ABR), function".
The Electronic Stability Program control unit reads in the signals from the rpm sensors and send them over the chassis CAN. The front SAM control unit and the video and radar sensor system control unit receive the rpm sensor signals over the chassis CAN.
The intelligent radar sensors receive the rpm sensor signals over the front end CAN from the front SAM control unit.
The video and radar sensor system control unit or the intelligent radar sensors use the rpm sensor signals to calculate the vehicle speed and direction of travel.
The trailer recognition status (with code (550) Trailer hitch) is sent by the trailer recognition control unit via the interior CAN, front SAM control unit and chassis CAN.
Blind Spot Assist:
The intelligent radar sensors read in all relevant information over the front end CAN.
For this purpose, the front SAM control unit routes the corresponding information from the chassis CAN to the front end CAN.
Active Blind Spot Assist:
The video and radar sensor system control unit reads in all relevant information over the chassis CAN and evaluates it.
To this end, the front SAM control unit routes all information sent over the body CAN from the body CAN to the chassis CAN.
The stage status (with code (237) Active Blind Spot Assist) is sent by the transmission control unit (with transmission 722) via the drive train CAN, CDI control unit or ME-SFI control unit and the chassis CAN to the video and radar sensor system control unit.
With code (237) Active Blind Spot Assist, the brake status is sent by the Electronic Stability Program control unit via the chassis CAN to the video and radar sensor system control unit.
The Blind Spot Assist system includes the following subfunctions:
^ Measuring procedure function sequence
^ System and warning messages function sequence
^ Function sequence for active intervention by the brake system (with code (237) Active Blind Spot Assist)
Measuring procedure function sequence
The acquisition of vehicles which are located in the blind spot is based on the radar measuring procedure.
The radar sensors emit pooled electromagnetic waves as so-called primary signals. If these impact with a vehicle that is located in the blind spot, they are reflected from it and received again by the corresponding wheel sensor as secondary signals. These signals are used to determine the distance and the speed of the recorded object as well as its angle relative to the systems vehicle.
The short-range radar sensors are ultra-wideband radar sensors with the following properties:
- Acquisition range s = 0.18 to 3 m
- Acquisition angle = 60° with angle determination and = 130° only detection (track)
- Radar sensor with f = 24 GHz carrier frequency
- Method of operation: short pulse method with f = 5 GHz band width
The range up to a maximum s = 200 m in front of the vehicle with code (237) Active Blind Spot Assist is monitored by the DISTRONIC controller unit (long range radar).
The monitoring range travel distance is flexibly configured and is regulated to match the vehicle speed.
The signals from the DISTRONIC controller unit are sent over the vehicle dynamics CAN to the video and radar sensor system control unit.
Detection range of radar sensor system with code (234) Blind Spot Assist, shown on model 204.0
1 Systems vehicle
2 Vehicle in blind spot
3 Left rear monitoring range
4 Right rear monitoring range
