Blind Spot Monitoring, Basic Function - GF54.71-P-9901A

Model All (4xWD) 

Model All (CAR) 

Overview 

This document contains information on:

• General information 
• Function requirements 
• Function 
  • Criteria for issuing a visual warning 
  • Criteria for issuing visual warnings and warning tones 
  • Active brake application 
  • Active Blind Spot Assist with exit warning function 
  • Rear Cross Traffic Alert 

General information 

Blind Spot Assist uses two radar sensors in the rear of the vehicle to monitor the area behind and beside the vehicle, the so-called blind spot. As of the market launch of model 223 and the Driving Assistance Package Gen. 5, two additional front radar sensors are installed on each side. Displays in the outside mirrors enable the system to warn when vehicles are in the blind spot. The system differentiates here between a warning zone and a collision zone.

The warning zone comprises a wide area next to and behind the vehicle. The collision zone comprises a narrower area. Both zones change to match the speed differential of the approaching vehicle. The higher the speed differential is, the further the two zones extend.

In event of any danger (vehicle within warning zone) the display in the outside mirror and in the instrument cluster lights up. If the driver changes lane after operating a turn signal indicator, the system warns acoustically of vehicles entering the collision zone.

Blind Spot Assist serves as a supplement to the outside mirrors. It does not release the driver from their obligation to change lanes of their own accord and to do so safely.

Blind Spot Assist is operated using the multimedia system.

Vehicles with Driving Assistance Package:

Blind Spot Assist can initiate course-correcting brake applications in the event of an imminent collision. This guides the vehicle back into the lane. This can help prevent an accident or reduce the consequences of an accident. Course correcting brake applications can also be made for objects at the side of the vehicle (as with applications made for objects in the blind spot) (as of market launch of model 223). Approaching cyclists can also be detected.

Function requirements 

• Engine running or drivetrain operational
• Forward movement of the vehicle (defined by the wheel rotation direction)
• Vehicle speed above 12 km/h (exit warning also possible at vehicle standstill)
• No trailer operation (vehicles with trailer hitch)

Function 

The Blind Spot Assist process is shown in an animation below https://moba.i.mercedes-benz.com/baix/cars/223.0_mbux-premium_2022_a/en_GB/page/highlight.html. 

The S-Class is used in the animation example.

The radar sensors record vehicles behind and next to the vehicle. Blind Spot Assist warns the driver with differing levels of intensity depending on the hazard potential involved. If a vehicle enters a warning zone at a speed of more than 12 km/h, the driver is warned by the display in the outside mirror lighting up. The display in the outside mirror lights up permanently red.

Criteria for issuing a visual warning 

• A vehicle approaches from behind and reaches the warning zone within approx. 2.5 s.
• A vehicle approaches from the side, and the outer edge of the vehicle moves into the warning zone.
• An overtaking vehicle with a speed differential of less than approx. 15 km/h is in the warning zone.

If a lane change is initiated (turn signaling) and a vehicle is located in the collision zone, the display in the outside mirror lights up in red. Warning tones are also issued. Depending on the model series and equipment involved, the warning is also shown in the assistance display of the instrument cluster.

Criteria for issuing visual warnings and warning tones 

• A vehicle approaches from behind and reaches the collision zone within approx. one second.
• A vehicle approaches from the side, and the outer edge of the vehicle moves into the collision zone.
• An overtaking vehicle with a speed differential of less than approx. 9 km/h is in the collision zone.

Active brake application 

Vehicles with Driving Assistance Package.

Additional function requirements for active brake application:

• Vehicle speed > 30 and < 200 km/h
• Tire pressure of all wheels within the tolerance range (run-flat mode inactive) (vehicles with tire pressure monitoring system)
• Active brake application approved by yaw rate interface

A course-correcting brake application also requires the traffic area in front of the vehicle to be monitored and then analyzed to ensure enough space is available for possible system reactions. This analysis is used for situation-based adaptation of any required course corrections.

The traffic area in front of the vehicle is monitored using radar sensors located behind the radiator shell and the multifunction camera hinter located behind the windshield. If vehicles or obstacles are detected at the side, close next to one's own vehicle or if any obstacles are expected soon, course corrections must then be reduced in this direction or course corrections must be completely avoided. The side distance, closing speed to the vehicles or obstacles and the driver's reaction time must be evaluated here.

Depending on the vehicle speed involved, course-correcting brake applications are perceived by the driver to be vehicle deceleration or yaw motion. If the driver steers against the effect of a course-correcting brake application or if they press hard on the accelerator pedal during an application, then the course-correcting brake application is ended.

If the vehicle is cornering or if the driver wishes to change lane, a course correcting brake application is adapted to meet the current driving condition. During vehicle longitudinal or lateral acceleration, for example, during considerable braking maneuvers or fast evasive maneuvers, course-correcting brake application does not take place.

If a driving safety system with a higher priority intervenes, for example the Electronic Stability Program (ESP®) or Active Brake Assist, the course-correcting brake application is suppressed. The ESP® control unit coordinates all the braking requests.

The driver is notified in the instrument cluster that the system has detected the risk of a side collision with a vehicle in the blind spot and that it is introducing a course correction. The display and warning for vehicles in the blind spot are also available to the driver at vehicle speeds over 200 km/h.

Active Blind Spot Assist with exit warning function 

When the vehicle is parked after a journey, Blind Spot Assist remains active for up to 3 minutes after "ignition OFF". The exit warning warns vehicle occupants about possible collisions with cyclists or vehicles when exiting the vehicle.

Example illustration of warning messages 

Courtesy of MERCEDES-BENZ USA

If a vehicle enters the collision zone at a speed of approx. 2 m/s, the display in the outside mirror lights up (A).

If a vehicle occupant then opens a door, a warning tone sounds and the display in the outside mirror starts to flash (B). If installed, the ambient lighting in the doors also lights up red (flashes).

The indicators in the outside mirrors flash 3 times immediately before the exit warning is no longer available 3 minutes after "ignition OFF".

The exit warning is an aid only and it is not a substitute for the attentiveness of the vehicle occupants. Responsibility for opening and closing the doors and leaving the vehicle lies at all times with the vehicle occupants.

Rear Cross Traffic Alert 

The Rear Cross Traffic Alert function is a partial function of Active Parking Assist (235) in combination with Blind Spot Assist (code 234) or the Driving Assistance Package (code 23P) or the Driving Assistance Plus Package (code P20).

Depending on the equipment installed, the system can warn against traffic crossing when reversing out of a parking space.

If a critical situation is detected, a corresponding symbol will appear on either the left or right side of the camera image in the multimedia system.

A visual warning is issued when the vehicle is at a standstill.

If the warning is not followed by a reaction from the driver, the vehicle may be braked automatically.

The function is switched on and off using the maneuvering assistant.

The function is not available on inclines, when driving with a trailer or if the radar sensors are concealed by vehicles or other objects.

	Function schematics
	Monitor blind spot function schema	Model 465	PE54.71-P-2502-97E
		Model 118, 167, 177, 243, 247, 293 with code 234 (Blind Spot Assist) except code 233 (Adaptive cruise control Plus (DISTRONIC PLUS)) Model 213, 238, 257, 290 as of model year 2021 with code 234 (Blind Spot Assist) except code 233 (Adaptive cruise control Plus (DISTRONIC PLUS))	PE54.71-P-2502-97A
		Model 118, 167, 177, 243, 247, 293 with code 233 (Adaptive cruise control Plus (DISTRONIC PLUS)) Model 213, 238, 257, 290 as of model year 2021 with code 233 (Adaptive cruise control Plus (DISTRONIC PLUS))	PE54.71-P-2502-97B
		Model 223, 297	PE54.71-P-2502-97C
		Model 192, 206, 214, 232, 236, 254, 294, 295, 296	PE54.71-P-2502-97D
	Additional basic functions
	Brakes, basic function		GF42.00-P-9900A
	Driver activity detection, basic function		GF54.30-P-1000A
	Traffic area monitoring, basic function		GF54.71-P-1000A
	Ambient lighting, basic function	Vehicles with ambient lighting	GF82.20-P-9901A
	Intelligent driving control unit, basic function		GF30.30-P-9890A
	Electronic Stability Program control unit, basic function		GF42.45-P-9890A
	Blind spot monitoring radar sensor controller unit, basic function	Model all (CAR) with code 234 (Blind Spot Assist) except code 233 (Adaptive cruise control Plus (DISTRONIC PLUS))	GF54.71-P-9891A