Blind Spot Assist, function - GF54.71-P-0003GN
MODEL 166 as of model year 2016 with CODE 234 (Blind Spot Monitoring)
MODEL 292 with CODE 234 (Blind Spot Monitoring)
Block diagram, except model 166.063
Block diagram, model 166.063
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) (except model 166.063))
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, Blind Spot Assist acts as an extension of the 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 via the warning buzzer in the instrument cluster.
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 outer rear bumper radar sensor. In other words, the integrated outer left rear bumper radar sensor sends its information via chassis CAN 1 to the integrated outer right rear bumper radar sensor, which evaluates the corresponding information from both integrated 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 integrated rear bumper radar sensors among other things:
- Terminal 15 status
- "Blind Spot Assist" status
- Engine running or drive train operational
- Vehicle moving forward
- Vehicle speed
- Trailer recognition status (with CODE 550 (Trailer hitch) (except model 166.063))
Circuit 15 status:
The electronic ignition lock control unit sends the status of circuit 15 via chassis CAN 1 to the integrated rear bumper radar sensors.
"Blind Spot Assist" status:
The instrument cluster sends the status of the Blind Spot Assist via chassis CAN 2, electronic ignition lock control unit and chassis CAN 1 to the integrated rear bumper radar sensors.
Engine running or drive train operational
- (Except model 166.063) The CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or "Drivetrain operational" signal via chassis CAN 1 to the integrated rear bumper radar sensors.
- (Model 166.063) The ME-SFI [ME] control unit sends the "Engine running" or "Drivetrain operational" signal via engine CAN, powertrain control unit and chassis CAN 1 to the integrated rear bumper radar sensors.
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 integrated 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 integrated rear bumper radar sensors. Trailer recognition status (with CODE 550 (Trailer hitch) (except model 166.063)):
If a trailer is detected, the trailer recognition control unit (with CODE 550 (Trailer hitch)) sends the "Trailer detected" status via interior CAN, electronic ignition lock control unit and chassis CAN 1 to the integrated rear bumper radar sensors.
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
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 rear ISO monitored area
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 system errors are detected, the Blind Spot Assist readiness and warning indications light up in yellow.
The status of functional readiness or the request to output fault messages is sent by the integrated rear bumper radar sensors via chassis CAN 1, 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; shown on 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 red 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 by the 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 the driver still attempts to change the lane and indicates this by operating the combination switch (sets turn signal) despite the illumination of the Blind Spot Assist readiness and warning indicator, a dual warning tone is also output via the warning buzzer in the instrument cluster that 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 reads in the position of the combination switch directly and sends it via chassis CAN 1 to the integrated rear bumper radar sensors.
Blind Spot Assist warning indication, 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" | X | |||
| Vehicle recognized in blind spot | X | |||
| Turn signal active, vehicle detected in blind spot | 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 via:
(Except model 166.063) drive train CAN, CDI control unit or ME-SFI [ME] control unit and chassis CAN 1 to the electronic ignition lock control unit.
(Model 166.063) Drive train CAN, powertrain control unit, and chassis CAN 1 to the electronic ignition lock control unit.
The electronic ignition lock control unit generates the "Reverse gear engaged" status and sends it via chassis CAN 1 to the integrated rear bumper radar sensors.
| Electrical function schematic, blind spot assistant | PE54.71-P-2051-97NBA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998GN |