Active Blind Spot Assist, Function - GF54.71-P-0006GN
MODEL 166
as of model year 2016
with CODE 237 (Active Blind Spot Assist)
MODEL 292
with CODE 237 (Active Blind Spot Assist)
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
- Soiling and function test on radar sensor system completed successfully
Object recording (e.g. vehicle ahead) via the radar sensor system is based on the radar measuring procedure.
The front long range radar sensor and the bumper radar sensors perform a soiling and function test after each engine start to ensure that they are functioning correctly. The function test requires an object to be located in the respective detection area (this object is used as a reference value). If a malfunction is detected or no objects (for the function test) are present in the detection range, Active Blind Spot Assist no longer engages in course-correcting intervention. The passive function is retained. A message appears in the instrument cluster: "Radar sensor system soiled". The displays in the mirror remain intact. The radar sensors control unit receives the signals of the bumper radar sensors over the radar-CAN 1 and sends them over the chassis FlexRay to the front long range radar sensor. The front long range radar sensor evaluates them in combination with its own signals and, when all the radar sensors are functioning correctly, sends the "Radar sensor system operational" status via the chassis FlexRay to the radar sensors control unit (with CODE 23P (Driving assistance package plus)).
- Vehicle moving forward
- Vehicle speed: v > 30 km/h
- No driving with a trailer (with CODE 550 (Trailer hitch) (except model 166.063))
Active Blind Spot Assist, general
The Active 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. It does not release the driver of his/her obligation to perform lane changes safely on his/her own responsibility.
The visual warning output takes place via the following components:
- Left Blind Spot Assist readiness and warning indicator
- Right Blind Spot Assist readiness and warning indicator
The acoustic warning is emitted through the warning buzzer that is directly actuated by the instrument cluster. Active Blind Spot Assist can additionally perform brake system interventions to correct the course, taking the surroundings of the vehicle into account. The active interventions by the brake system are performed on specific wheels and have a course-correcting effect on the vehicle. If a risk of collision is detected with vehicles that are in the blind spot, then an accident can be avoided or the consequences of the accident lessened.
The area that cannot be observed via the outside mirrors is monitored by the following components:
- Left outer rear bumper radar sensor
- Right outer rear bumper radar sensor
The course-correcting intervention is dependent on the road space in front of the vehicle being monitored to avoid any collisions with other road user (incl. oncoming traffic) because of any change in direction.
Monitoring of the road in front of the vehicle is performed by the following components:
- Front long-range radar sensor
- Left front bumper radar sensor
- Right front bumper radar sensor
The radar sensors control unit (with CODE 23P (Driving Assistance package Plus)) reads in and evaluates the signals of the front bumper radar sensors over radar CAN 1, the signals of the rear bumper radar sensors over radar CAN 2 and the signals of the front long range radar sensor over the chassis FlexRay.
Illustration of the "Active Blind Spot Assist" principle
The following, among other information, is evaluated by the radar sensors control unit:
- Terminal 15 status
- "Active Blind Spot Assist" status
- Engine running or drive train operational
- Vehicle in forward movement, vehicle speed
- Driving stage engaged
- Brake status
- Trailer recognition status (with CODE 550 (Trailer hitch) (except model 166.063))
Circuit 15 status:
The electronic ignition lock control unit sends the circuit 15 status over the chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)) and the chassis FlexRay to the radar sensors control unit.
"Active Blind Spot Assist" status:
The instrument cluster sends the status of the Active Blind Spot Assist over the chassis CAN 2, electronic ignition lock control unit, chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
Engine running or drive train operational
- (Except model 166.063) The CDI control unit or ME-SFI [ME] control unit sends the "Engine running" or "Drivetrain operational" signal over the chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
- (Model 166.063) The ME-SFI [ME] control unit sends the "Engine running" or "Drivetrain operational" signal via the engine CAN, powertrain control unit, chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
Vehicle in forward movement, vehicle speed:
Forward movement is defined via the wheel rotation direction. The vehicle speed is calculated from the wheel speed. The Electronic Stability Program control unit sends this information via the chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit. The radar sensors control unit uses it to calculate the vehicle speed and defines the direction of travel.
Engaged drive position:
- (Except model 166.063) The fully integrated transmission control unit sends information about the gear range engaged via the drive train CAN, CDI control unit or ME-SFI [ME] control unit, chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
- (Model 166.063) The fully integrated transmission control unit sends information about the gear range engaged over the drive train CAN, powertrain control unit, chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
Brake status:
The status of the brake is sent by the Electronic Stability Program control unit via the chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
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 the interior CAN, electronic ignition lock control unit and chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
The Active Blind Spot Assist consists of the following subfunctions:
- Measuring procedure function sequence
- System and warning messages function sequence
- Function sequence for active intervention by the brake system
Measuring procedure function sequence
Vehicles are detected based on the radar measuring procedure. The radar sensors emit bundled electromagnetic waves as "primary signals". If these waves hit an object (vehicle in the blind spot), they are reflected by it and received again by the corresponding 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 monitored area is designed to be flexible and is controlled as a function of the vehicle speed. The signals from the front long-range radar sensor are received by the radar sensors control unit over the chassis FlexRay.
The radar sensors control unit reads in and evaluates the signals of the front bumper radar sensors over radar CAN 1, the signals of the rear bumper radar sensors over radar CAN 2 and the signals of the front long-range radar sensor over the chassis FlexRay.
Recording range of radar sensor system incl. front road space monitoring
The detection ranges of the radar sensor system are based on the angle at which the radar waves are emitted. These are extrapolated by the radar sensors control unit to calculate 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 Active 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 circuit 15 status is sent by the electronic ignition lock control unit over chassis CAN 1, the chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)) and the chassis FlexRay to the radar sensors control unit.
The system readiness status or request for outputting error messages is sent by the radar sensors control unit via the chassis FlexRay, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), chassis CAN 1, electronic ignition lock control unit, and chassis CAN 2 to the instrument cluster and via the chassis FlexRay, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), chassis CAN 1, electronic ignition lock control unit, and interior CAN to the left front door or right front door control unit. The left front door control unit or the right front door control unit then actuates the corresponding Blind Spot Assist readiness and warning indicator.
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.
Overtaking vehicles are detected and a warning is issued, regardless of their relative speed to the vehicle, via Active 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 lanes and indicates this by operating the combination switch (sets turn signal indicator), 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 steering column tube module control unit directly reads in the position of the combination switch and sends this information via the chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
The function status "Off" display is shown when Active Blind Spot Assist is deactivated and in the event of a fault.
When the Active Blind Spot Assist is switched on via the "Assistance" menu in the instrument cluster, function status "On" is displayed. The Active Blind Spot Assist is activated but not ready to issue a warning because the additional function requirements such as vehicle speed v > 30 km/h are not met. When the function status "Operational" is issued by instrument cluster, the Active Blind Spot Assist is switched on and all additional function requirements are met. The Active Blind Spot Assist is ready to issue a warning.
Blind Spot Assist readiness indicator
Blind Spot Assist warning indicator
The following table contains the requirements for displaying system readiness and for showing the visual warning messages:
| 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 | 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 | |||
| Drive position "R" engaged | X | |||
| Vehicle recognized in blind spot | X | |||
| Turn signal active, vehicle detected in blind spot | X | |||
| Course-correcting intervention by the brake system active | 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.
Additional function requirements for active intervention by the brake system
- ESP® not switched passively
- ESP® not in active diagnostic or dynamometer test mode
- ESP® not in rpm/speed control mode
- Anti-lock braking system (ABS), acceleration skid control (ASR), Brake Assist System (BAS), ESP®, PRE-SAFE® brake, or electronic traction system (ETS) not active
- Driving speed v<200 km/h
- Approval issued for active intervention by the brake system for yawing moment interface
The Electronic Stability Program control unit sends the status of the ESP® system via the chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
Lateral and longitudinal acceleration are detected by the turn rate sensor for lateral and longitudinal acceleration. The yaw rate sensor for lateral and longitudinal acceleration transmits appropriate values via the dynamics CAN to the Electronic Stability Program control unit. The Electronic Stability Program control unit evaluates this data and sends it via the chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
Function sequence for active intervention by the brake system
If the radar sensors control unit detects the threat of an imminent side collision with a vehicle in the blind spot, in particular during a lane change, a course-correcting intervention by the brake system is requested. For this purpose, the radar sensors control unit sends the corresponding request over the chassis FlexRay, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis CAN 1 to the Electronic Stability Program control unit. The Electronic Stability Program control unit then selectively brakes individual wheels and moves the vehicle back onto a collision-free course using the traction system hydraulic unit.
If, during an intervention by the brake system, the driver steers opposite to the intervention by the brake system (i.e. overrides the intervention by the brake system) or if the vehicle is accelerated, the intervention by the brake system is immediately canceled.
The driving assistance systems or driving safety systems ASR, BAS, ESP®, ETS, trailer stabilization (with CODE 550 (Trailer hitch) (except model 166.063)), and PRE-SAFE® brake are of a higher priority than the Active Blind Spot Assist and result in the termination of the active brake intervention.
If the ABS system is actively intervening, an Active Blind Spot Assist intervention by the brake system is not initiated. During such an intervention by the brake system, the ABS may reduce the intensity of the intervention by the brake system, the intervention by the brake system itself however is continued with.
Course-correcting interventions by the brake system are always suppressed, when one of the following conditions occurs:
- Rapid or greater loss of pressure in a tire.
On vehicles with CODE 475 (Tire pressure monitor), the respective tire pressure is evaluated by the tire pressure monitor control unit (with CODE 475 (Tire pressure monitor)). The tire pressure monitor control unit (with CODE 475 (Tire pressure monitor)) sends information about the respective tire pressure via the chassis CAN 2, electronic ignition lock control unit, chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit. On vehicles with CODE 477 (Tire pressure loss warning), the tire pressure is determined based on the rolling circumference. The tire pressure loss warning (RDW) system is functionally integrated in the Electronic Stability Program control unit.
- Risk of frontal collision of vehicle with vehicle or obstacle in the direction of travel with output of a collision-critical distance warning (with constant movement conditions).
- Acceleration or deceleration of the vehicle in the longitudinal direction as well as lateral acceleration of a = 4 m/s2
(at a vehicle speed of v > 120 km/h) to 6 m/s2 (at a vehicle speed of v < 80 km/h).
The acceleration forces are recorded by the yaw rate sensor for lateral and longitudinal acceleration. The turn rate sensor for lateral and longitudinal acceleration sends the acceleration force values via the vehicle dynamics CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
- Jerky steering motion by the driver with a steering wheel velocity > 300°/s.
Steering movements are recorded by the steering wheel angle sensor. The steering column tube module control unit directly reads in the signals of the steering wheel angle sensor and sends information about the steering wheel angle and steering wheel velocity via the chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
- Course-correcting steering interventions by the driver (change in steering wheel angle > 5°) or change in specified torque as a result of depressing the accelerator pedal (change in accelerator pedal position > 10%).
The CDI control unit or ME-SFI [ME] control unit sends information about the accelerator pedal position via the chassis CAN 1, chassis gateway control unit (with CODE 23P (Driving Assistance package Plus)), and the chassis FlexRay to the radar sensors control unit.
Shows model 166.0
If vehicles are located very close in the blind spot on both sides of the vehicle with Active Blind Spot Assist, a course-correcting brake intervention is suppressed.
Shows model 166.0
If an obstacle is located at the side next to the vehicle with Active Blind Spot Assist, the position of which cannot be determined, a course-correcting intervention by the brake system in the direction of the obstacle is suppressed.
Shows model 166.0
If a stationary obstacle is detected very close on one side of the vehicle with Active Blind Spot Assist, a course-correcting intervention by the brake system in the direction of the obstacle is suppressed.
Shows model 166.0
In the event of an imminent risk of collision with a vehicle in front and a vehicle in the blind spot, a course-correcting intervention by the brake system is suppressed.
An acoustic warning is not issued!
Shows model 166.0
In the event of an imminent risk of collision with a stationary obstacle and a vehicle in the blind spot, a course-correcting intervention by the brake system is suppressed.
An acoustic warning is not issued!
Shows model 166.0
In the case of oncoming traffic, course-correcting intervention by the brake system is limited so that any collision with oncoming traffic is avoided.
| Electrical function schematic, Active Blind Spot Assist | PE54.71-P-2055-97NBA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998GN |