Blind Spot Assist, function - GF54.71-P-0003FQM
MODEL 218 as of model year 2015 with CODE 234 (Blind Spot Monitoring)
Function requirements, general
- No undervoltage or overvoltage
- "Blind Spot Assist" in "Assist" menu in the instrument cluster activated
- Engine running or drive train operational
- Vehicle moving forward
- Vehicle speed: v ≥ 30 km/h
- No trailer operation (with code (550) trailer hitch)
Blind Spot Assist, general
The 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. In a broader sense, the Blind Spot Assist acts 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.
In the respective outside mirror, a visual indicator indicates the status of the Blind Spot Assist and warns of critical situations during a lane change (i.e. a vehicle is in the "blind spot"). In addition, an acoustic warning can be issued.
The visual warning is issued over the Blind Spot Assist warning lamp in each outside mirror.
The acoustic warning is emitted via the warning buzzer.
The area which cannot be observed via the outside mirror and inside rear-view mirror is monitored by the following components:
- Left rear bumper intelligent radar sensor
- Right rear bumper intelligent radar sensor
All relevant data is evaluated by the rear bumper intelligent radar sensors, whereby the right rear bumper intelligent radar sensor requests the warning output.
The rear bumper intelligent radar sensors operate according to the "master-slave" principle. The master or slave function can be determined via the connector coding. The master function is defined for the right rear bumper intelligent radar sensor. In other words, the intelligent rear left bumper radar sensor sends its information via chassis CAN 1 to the intelligent rear right bumper radar sensor which then evaluates the corresponding information from both intelligent rear bumper radar sensors and sends corresponding requests or data via chassis CAN 1 to the corresponding control units.
Illustration of the Blind Spot Assist principle
The following information is evaluated by the intelligent rear bumper radar sensors:
- Terminal status of terminal 15
- "Blind Spot Assist" status
- Engine running or drive train operational
- Vehicle moving forward
- Vehicle speed
- Trailer recognition status (with code (550) Trailer hitch)
Status of circuit 15:
The circuit 15 status is sent by the electronic ignition lock control unit via chassis CAN 1 to the intelligent rear bumper radar sensors.
"Blind Spot Assist" status:
The instrument cluster sends the status of the Blind Spot Assist to the rear bumper intelligent radar sensors via chassis CAN 2, the front SAM control unit and chassis CAN 1.
Engine running or drive train operational
The CDI control unit or the ME-SFI control unit sends the "Engine running" or "Drive train operational" signal to the rear bumper intelligent radar sensors via chassis CAN 1, the front SAM control unit and chassis CAN 1.
Vehicle moving forward:
Forward movement is defined via the wheel rotation direction. The Electronic Stability Program control unit sends the information about the wheel rotation direction via chassis CAN 1 to the intelligent rear bumper radar sensors.
Vehicle speed:
The vehicle speed is calculated from the wheel speed. The Electronic Stability Program control unit sends the information about the wheel speed via chassis CAN 1 to the intelligent rear bumper radar sensors.
Trailer recognition status (with code (550) Trailer hitch):
If a trailer is detected, the trailer recognition control unit sends the "Trailer detected" status to the rear bumper intelligent radar sensors via the interior CAN, the front SAM control unit and chassis CAN 1.
The Blind Spot Assist system includes the following subfunctions:
- Measuring procedure function sequence
- System and warning messages function sequence
Measuring procedure function sequence
Objects (vehicle in blind spot) are detected using the radar measuring procedure. The intelligent rear bumper radar sensors emit bundled electromagnetic waves as "primary signals". If these waves hit an object, they are reflected by it and are received again by the corresponding intelligent rear bumper 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.
Detection range of radar sensor system; shown is model 218.3
The detection ranges of the rear bumper intelligent radar sensors are based on the angle at which the radar waves are emitted. They are extrapolated by the respective rear bumper intelligent radar sensor to produce the actual monitoring ranges.
Illustration showing actual rear monitoring range; shown is model 218.3
System and warning messages function sequence
When circuit 15 is switched on the Blind Spot Assist warning lamps light up red for t = 1.5 s and then yellow. When a vehicle speed of v > 30 km/h is reached, the Blind Spot Assist warning lamps go out again and the Blind Spot Assist is ready to issue warnings.
If system errors are found, a corresponding message appears in the multifunction display of the instrument cluster, and the Blind Spot Assist warning lamps light up yellow.
The operational readiness status is sent by the intelligent rear right bumper radar sensor via chassis CAN 1, the front SAM control unit and interior CAN to the respective front door control unit, which consequently actuates the corresponding Blind Spot Assist warning lamp. The request to output fault messages is sent to the instrument cluster by the intelligent rear right bumper radar sensor via chassis CAN 1, the front SAM control unit and chassis CAN 2.
Readiness of Blind Spot Assist, shown on left outside mirror
If at a speed of v ≥ 30 km/h a vehicle is located in the acquisition range of the radar sensor system, the driver is warned by the warning lamp for Blind Spot Assist lighting up red in the in outside mirror, on the side of which the vehicle is in the blind spot. When vehicles are passing, they are recognized and a warning is issued regardless of their relative speed to the vehicle with Blind Spot Assist. Due to the short reaction time when the difference in speed is high, the warning message output sometimes does not have any added value. If, despite the Blind Spot Assist warning lamp lighting up, the driver attempts to perform a lane change and signals this by actuating the combination switch (activating the turn signal), an additional double warning tone is emitted by the warning buzzer which is directly actuated by the instrument cluster. The request to emit a double warning tone is sent to the instrument cluster by the intelligent rear right bumper radar sensor via chassis CAN 1, the front SAM control unit and chassis CAN 2. The Blind Spot Assist warning lamp flashes. If the vehicle leaves the acquisition range of the radar sensor system, the red flashing Blind Spot Assist warning lamp is switched off.
The signal path for issuing warning messages corresponds to that for displaying function readiness.
The steering column tube module control unit reads in the position of the combination switch directly and sends it to the rear bumper intelligent radar sensors via chassis CAN 1.
Blind Spot Assist warning indicator, shown on left outside mirror
The requirements for displaying functional readiness and for issuing visual warning messages are given in the following table.
| Operating state | Blind Spot Assist warning lamp "Off" | Warning lamp for Blind Spot Assist lights up yellow | Warning lamp of Blind Spot Assist lights up red | Warning lamp for Blind Spot Assist flashes red |
|---|---|---|---|---|
| Circuit 15 OFF | X | |||
| Terminal 15 ON | X | |||
| Engine running or drive train operational | X | |||
| Vehicle accelerates, vehicle speed v ≥30 km/h | X | |||
| Vehicle decelerates, vehicle speed v ≥25 km/h | X | |||
| Trailer recognized (with code (550) Trailer hitch) | X | |||
| Drive position "R" engaged | X | |||
| Vehicle recognized in blind spot | X | |||
| Turn signal active, vehicle detected in blind spot | X | |||
| Course-correcting intervention by the brake system active | X | |||
| Fault in Blind Spot Assist system | X |
Gear range "R" engaged: Engaging gear range "R" takes place via the fully integrated transmission control unit. The fully integrated transmission control unit then sends the status "gear range R engaged" to the front SAM control unit via the drive train CAN, CDI control unit or ME-SFI control unit and chassis CAN 1. The front SAM control unit generates the "Reverse gear engaged" signal and sends it to the rear bumper intelligent radar sensors via chassis CAN 1.
| Electrical function schematic, blind spot assistant | PE54.71-P-2051-97XAE |
| Overview of system components for driver assistance systems | GF54.00-P-9998FQM |