Blind Spot Assist, function - GF54.71-P-0003FLM
MODEL 212 as of model year 2014 with CODE 234 (Blind Spot Monitoring)
The requirements for displaying functional readiness and for issuing visual warning messages are given in the following table.
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 the broader sense, the Blind Spot Assist system acts as an extension of the rear-view 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 via the Blind Spot Assist readiness and warning indicator in the respective outside mirror.
The area which cannot be observed via the outside mirror and inside rear-view mirror is monitored by the following components:
- Right rear bumper intelligent radar sensor
- Left rear bumper intelligent radar sensor
All relevant data is evaluated by the intelligent rear bumper radar sensors, whereby the intelligent right rear bumper 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.
The following information is evaluated by the Blind Spot Assist:
- "Blind Spot Assist" status
- Engine running or drive train operational
- Vehicle in forward movement/vehicle speed
- Trailer recognition (with CODE 550 (Trailer hitch))
"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 in forward movement/vehicle speed:
Forward movement is defined via the wheel rotation direction. The vehicle speed is calculated on the basis of the wheel speeds. The Electronic Stability Program control unit or the regenerative braking system control unit sends this information over chassis CAN 1 to the intelligent rear bumper radar sensors.
Trailer recognition (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
Vehicles are detected based on the radar measuring procedure. The intelligent rear bumper radar sensors emit bundled electromagnetic waves as "primary signals". If these waves hit an object (e.g. a vehicle in the blind spot), they are reflected from it and received again by the corresponding rear bumper intelligent 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 rear bumper intelligent radar sensors are designed as ultra-wideband radar sensors with the following properties:
- Acquisition range s = 0.18 to 30 m
- Detection angle: ≤ = 80° with angle measurement and ≤ = 130° only detection (tracking)
- Carrier frequency: f = 25 GHz
- Method of operation: Short pulse method with f = 1.4 GHz band width
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.
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 determined, a corresponding message is shown on the instrument cluster's multifunction display and the Blind Spot Assist readiness and warning indicators light up in yellow.
The right rear bumper intelligent radar sensor sends the function readiness status and/or the request to output fault messages via chassis CAN 1, the front SAM control unit and chassis CAN 2 to the instrument cluster (output of fault messages) and via chassis CAN 1, the front SAM 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 the Blind Spot Assist readiness and warning lamp lighting up, the driver still attempts to change lane and indicates this by operating the combination switch (operates turn signal), a double warning tone is additionally issued once by the warning buzzer in 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 curve for issuing warning messages corresponds to that of the display for 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 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 (v ≥20 mph) | X | |||
| Vehicle decelerates, vehicle speed v ≤25 km/h (v ≥16 mph) | X | |||
| Trailer recognized (with CODE 550 (Trailer hitch)) | X | |||
| Gear range "R" (with transmission 722.9, 724.2, 725) or reverse gear (with transmission 716) engaged | X | |||
| Vehicle recognized in blind spot | X | |||
| Turn signal active, vehicle detected in blind spot | X | |||
| Fault detected | X |
Status of circuit 15:
The circuit 15 status is sent by the electronic ignition lock control unit over chassis CAN 1 to the intelligent rear bumper radar sensors.
MODEL 212 with TRANSMISSION 722.9, 724.2, 725
as of model year 2014
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 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.
MODEL 212 with TRANSMISSION 716
as of model year 2014
with CODE 234 (Blind Spot Monitoring)
Reverse gear engaged:
Engaging of the reverse gear is detected by the backup lamp switch.
The front SAM control unit reads in the status of the backup lamp switch directly, 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-2051-97DAD | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998FLM |