Blind Spot Assist, function - GF54.71-P-0003RF
MODEL 205, 253 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 and inside rearview mirror. 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 via the Blind Spot Assist readiness and warning indicator in the respective outside mirror.
The acoustic warning is output over the instrument cluster speaker. The area which cannot be observed via the outside mirror and inside rear-view mirror is monitored by the following components:
- Right outer rear bumper integrated radar sensor
- Left outer rear bumper integrated radar sensor
All relevant data is evaluated by the integrated rear bumper radar sensors, whereby the right rear bumper radar sensor requests the warning output.
The integrated rear bumper 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 integrated right rear bumper radar sensor. In other words, the integrated left rear bumper radar sensor sends its information via the periphery CAN to the integrated right rear bumper radar sensor which evaluates the corresponding information from both integrated rear bumper radar sensors and sends corresponding requests or data via periphery CAN to the corresponding control units.
Illustration of the principle of Blind Spot Assist, shown on model 205.0
The following information is evaluated by the radar sensors integrated in rear bumper:
- Circuit 15 status
- "Blind Spot Assist" status
- Engine running or drive train operational
- Vehicle moving forward
- Vehicle speed
- Status of trailer recognition (with CODE 550 (Trailer hitch))
Status of circuit 15:
The electronic ignition lock control unit sends the status of circuit 15 via the periphery CAN to the radar sensors integrated in the rear bumper. "Blind Spot Assist" status:
The status of the Blind Spot Assist is sent by the instrument cluster via the user interface CAN, electronic ignition lock control unit and periphery CAN to the radar sensors integrated in the rear bumper.
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 train CAN, powertrain control unit, chassis FlexRay, electronic ignition lock control unit and periphery CAN to the radar sensors integrated in the rear bumper.
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 the chassis FlexRay, electronic ignition lock control unit and periphery CAN to the radar sensors integrated in the rear bumper.
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 the chassis FlexRay, electronic ignition lock control unit and periphery CAN to the radar sensors integrated in the rear bumper. Trailer recognition (with CODE 550 (Trailer hitch)):
When the trailer recognition control unit has detected a trailer, it sends the "Trailer detected" status to the integrated rear bumper radar sensors over the interior CAN, electronic ignition lock control unit and periphery CAN.
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 radar sensors integrated in the rear bumper 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 radar sensor integrated in the rear bumper 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 area of the radar sensor system, shown on model 205.0
The integrated rear bumper radar sensors detection range is based on the angles of the radar waves. These are extrapolated by the respective integrated rear bumper radar sensor to produce the actual monitoring ranges.
Illustration showing the actual rear monitoring range, shown on model 205.0
System and warning messages function sequence
When circuit 15 is switched on, the Blind Spot Assist readiness and warning indicators are switched on for t = 1.5 s turning first red then yellow. When a speed of v > 30 km/h is reached the Blind Spot Assist readiness and warning indicators are switched off and the Blind Spot Assist is ready for warning.
If a system error is detected, a corresponding message is shown in the multifunction display of the instrument cluster and the Blind Spot Assist readiness and warning indicators light up yellow.
The integrated right rear bumper radar sensor sends the function readiness status and/or the request to output fault messages over the periphery CAN, electronic ignition lock control unit and user interface CAN to the instrument cluster (output of fault messages) and over the periphery CAN, electronic ignition lock control unit and interior CAN to the respective front door control unit, which then actuates the corresponding Blind Spot Assist readiness and warning indicator.
Blind Spot Assist readiness indicator; illustration shows left outside mirror
If, at a speed of v ≥ 30 km/h, a vehicle is located in the radar sensor system sensing range, the driver is notified of it by the Blind Spot Assist readiness and warning indicator turning read in the outside mirror on the side of the vehicle on 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 illumination of the Blind Spot Assist readiness and warning indicator, the driver still attempts to change lane and indicates this by operating the combination switch (turn signal active), a dual warning tone is additionally output via the instrument cluster speaker, which is actuated directly by the instrument cluster. The Blind Spot Assist readiness and warning indicator flashes on and off. If the vehicle leaves the radar sensor system's sensing range, the red flashing Blind Spot Assist readiness and warning indicator is switched off.
The signal path for issuing warning messages corresponds to that for displaying function readiness.
The steering column tube module control unit directly reads in the switch position of the combination switch and sends it to the integrated rear bumper radar sensors over the chassis FlexRay, electronic ignition lock control unit and periphery CAN.
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 readiness and warning indicator off | Blind Spot Assist readiness and warning indicator, yellow on | Blind Spot Assist readiness and warning indicator, red on | Blind Spot Assist readiness and warning indicator, flashing red |
|---|---|---|---|---|
| Circuit 15 OFF | X | |||
| Circuit 15 ON (t > 1.5 s) | X | |||
| Circuit 15 ON (t > 1.5 s) | 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 | |||
| Gear range "R" (transmission 722, 724, 725) or reverse gear (transmission 716) engaged | X | |||
| Vehicle recognized in blind spot | X | |||
| Turn signal active, vehicle detected in blind spot | X | |||
| Fault detected | X |
MODEL 205, 253 with TRANSMISSION 722, 724, 725 with CODE 234 (Blind Spot Monitoring)
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, powertrain control unit and chassis FlexRay. The electronic ignition lock control unit generates the "Reverse gear engaged" status and sends it via the periphery CAN to the radar sensors integrated in the rear bumper.
MODEL 205, 253 with TRANSMISSION 716
with CODE 234 (Blind Spot Monitoring)
Reverse gear engaged:
Engaging the reverse gear is recorded by the manual transmission main shifter shaft position sensor. The CDI control unit or the ME-SFI [ME] control unit directly reads in the signals of the manual transmission main shifter shaft position sensor, uses it to generate the "Reverse gear engaged" signal and sends it to the integrated rear bumper radar sensors over the drive train CAN, powertrain control unit, chassis FlexRay, electronic ignition lock control unit and periphery CAN.
| Electrical function schematic, blind spot assistant | PE54.71-P-2051-97FBA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998RF |