GF54.71-P-0003GM Blind Spot Monitor, Function
GF54.71-P-0003GM Blind Spot Monitor, Function
MODEL 164.1
- with CODE (234) Blind Spot Assist
- as of model year 2011 /CY 10
MODEL 164.8, 251.0 /1
- with CODE (234) Blind Spot Assist
- as of Model Year 2011 /Modification year 10 Engineering refinement package
Blind Spot Assist function requirements, general
- Function of "Blind Spot Assist" in "Assist" menu activated in IC (A1)
- Engine running (circuit 61 On) n > 300 rpm
- Radar sensor system not switched off
- Vehicle moves forwards and gear range "D" is engaged
- Vehicle speed ≥30 km/h
- No trailer operation
Blind Spot Assist, general
The Blind Spot Assist monitors the rear area of the vehicle by means of short range radar and informs the driver if necessary that an intentional lane change (flasher set) is not recommended at a given point in time. The Blind Spot Assist serves in the further sense as an expansion of the rearview mirror; under no circumstances is the driver relieved of his responsibility for carrying out the lane change.
In the left electrically adjustable and heated outside mirror, (M21/1) and in the right electrically adjustable and heated outside mirror, (M21/2) a visual indicator provides information on the active condition of the system and on the critical condition (i.e. a vehicle is "in the "blind spot").
The visual warning output takes place via the following components:
- Left Blind Spot Assist readiness and warning indicator (M21/1e2)
- Right Blind Spot Assist readiness and warning indicator (M21/2e2)
The acoustic warning is issued through the following component:
- Warning buzzer (A1h1) in the IC
The area which cannot be observed via the outside mirror and inside rearview mirror is monitored by the following components:
- Intelligent radar sensor for left rear bumper (B29/4)
- Intelligent radar sensor for right rear bumper (B29/5)
All the relevant data is evaluated by the radar sensors, the right radar sensor requesting the warning output.
The radar sensors work according to the Master/Slave principle. The master or slave function can be determined via the connector coding.
The master function is determined for the right radar sensor. In other words, the left radar sensor transmits its information via the engine compartment CAN (CAN C) to the right radar sensor which evaluates the corresponding information from both radar sensors and passes on corresponding requests or data to the corresponding control units via the engine compartment CAN
The following information is read in by the radar sensors:
- Status of function "Blind Spot Assist"
- Engine running (circuit 61 On) n > 300 rpm
- Vehicle moves forwards and gear range "D" is engaged
The instrument cluster transmits the status of the "Blind Spot Assist" to the radar sensors via the engine compartment.
The engine rpm is transmitted via the CDI control unit (N3/9) (on diesel engine) or the ME-SFI control unit (N3/10) (on gasoline engine) to the radar sensors via the engine compartment-CAN.
The status "Gear range D engaged" is defined via the transmission selector lever position.
For this the fully integrated transmission control unit (VGS) (Y3/8n4) (except model 164.195) or fully integrated hybrid transmission control controller unit (Y3/10) (model 164.195) transmits the transmission selector lever position to the radar sensors via the engine compartment CAN.
The forward movement is defined via the wheel rotation direction and the vehicle speed via the wheel speed.
The wheel rotation direction and the wheel speed is recorded by the following components:
- Left front rpm sensor (/)L6/1
- Right front rpm sensor (/)L6/2
- Left rear rpm sensor (/)L6/3
- Right rear rpm sensor (/)L6/4
The ESP control unit (47-5) (except model 164.195) or the RBS control unit (N30/6) (on model 164.195) reads in the signals from the rpm sensors and transmits these via the engine compartment CAN to the radar sensors which calculate from this the vehicle speed.
The Blind Spot Assist is made up of the following subfunctions:
- Measuring procedure function sequence
- System and warning messages function sequence
Measuring procedure function sequence
The acquisition of vehicles which are located in the blind spot is based on the radar measuring procedure. In the process, electromagnetic waves from radar sensors are bundled and sent out 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.
The distance and speed of the recorded object can be calculated from these signals.
The radar sensors are ultra wideband radar sensors with the following properties:
- Acquisition range s = 0.5 to 3 m
- Acquisition angle = 80° with angle determination and angle = 140° only detection (track)
- Radar sensor with f = 24 GHz carrier frequency
- Method of operation: Short pulse method with f = 5 GHz band width
Schematic representation of monitoring range
1 Systems vehicle
2 Vehicle in blind spot
3 Left rear monitoring range
4 Right rear monitoring range
A s = 3 m
B s = 0.5 m
Automatic shutoff of radar sensor system
In the vicinity of radio-astronomy stations the radar sensor system is switched off automatically due to the legal requirements on the 24- GHz-Radar system (short range radar) .
In other words the Blind Spot Assist is not functional in these ranges.
The protection ranges around the radio astronomy stations are stored in the right radar sensor.
The radio and navigation unit (A2/56) (with code (511) audio 50 APS incl. DVD changer or code (525) MB Audio 50 APS radio) or the COMAND operating, display and controller unit (A40/3) (with code (512) COMAND APS incl. DVD changer or code (527) COMAND APS with single DVD drive (with navigation)) transmits corresponding location information from the NAV via the interior CAN (CAN B), central gateway control unit (N93) and engine compartment CAN to the radar sensors.
When the Blind Spot Assist is active the message "Radar sensor system automatically switched off, see operating instructions" is displayed in the multifunction display (A1p13) of the instrument cluster.
The Blind Spot Assist readiness and warning indicators light up in yellow.
If the vehicle is parked in a restricted area, then when it is started up again the Global Positioning System (GPS) coordinates are used for position finding. The driver is notified again that the radar sensor system was automatically switched off.
If the vehicle leaves the restricted area, the radar sensor system is automatically switched on again.
The "radar sensor system automatically switched off, see operator's manual" message is canceled and the yellow Blind Spot Assist readiness and warning indicator lamps are switched off.
Manual switching on/off of the radar sensor system:
There is also the possibility of switching the radar sensor system off and on again manually via the "Vehicle" menu in the IC.
If the radar sensor system was automatically switched off within a restricted area, the manual switch-on option is no longer available and the following message is shown "Radar sensor system automatically switched off, see operator's manual".
Schematic representation of automatic shutoff of radar sensor system, shown on model 164.1
A1p13 Multifunction display
A2/56 Radio and navigation unit (with code (511) Audio 50 APS with DVD changer or with code (525) MB Audio 50 APS radio)
A2/93a6 GPS antenna
A40/3 COMAND operating, display and controller unit (with code (512) COMAND APS with 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
GPS Global Positioning System
RAS Radio astronomy station
Std. Protective 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 a system fault is found, a corresponding message appears in the multifunction display and the readiness and warning indicators for the Blind Spot Assist light up yellow.
The EZS control unit (N73) transmits the circuit status of circuit 15 via the engine compartment CAN.
The status of the system readiness or the request for output of fault messages is transmitted by the right intelligent radar sensor via the engine compartment CAN to the IC and the central gateway control unit.
The central gateway control unit receives the status of the system readiness via the engine compartment CAN and conducts these via the interior CAN to the left front DCU or right front DCU which thereupon actuates the corresponding readiness and warning indicator for the Blind Spot Assist.
Blind Spot Assist in readiness, shown on left outside mirror
M21/1e2 Left Blind Spot Assist readiness and warning indicator
If at a speed of v ≥30 km/h (v ≥20 mph with code (494) USA version) a vehicle is located in a recording range of the radar sensor system, the driver is warned by the red lighting up of the readiness and warning indicator for the Blind Spot Assist in the outside mirror, on which side the vehicle is in the blind spot.
Overtaking vehicles are reliably warned up to a relative speed of v = 35 km/h.
Vehicles with a higher relative speed may- under certain circumstances - be detected too late or not at all. As a consequence, any warning may then come too late or not at all.
If the driver tries to initiate a lane change despite the lighting up of the readiness and warning indicator for the Blind Spot Assist and signals this by operating the combination switch (S4) (set flasher), in addition the output of a one-time dual warning tone takes place by the warning buzzer in the IC. The readiness and warning indicator for Blind Spot Assist flashes red.
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 issue of warning messages corresponds to that of the display for system readiness.
The switch position of the combination switch is read in directly from the steering column tube module control unit and transmitted to the radar sensors via the engine compartment CAN.
Vehicle in blind spot (in recording range of radar sensor system), shown on left outer outside mirror
M21/1e2 Left Blind Spot Assist readiness and warning indicator
The requirements for display of system readiness and for output of optical warning messages can be obtained from the following table.
