Collision Prevention Assist Function - GF30.30-P-0010RR
Model 190
with code 258 (COLLISION PREVENTION ASSIST)
Shown up to 30.11.2018
Shown as of 01.12.2018
Function requirements, general
- COLLISION PREVENTION ASSIST coded in the electronic ignition lock control unit (N73)
- No undervoltage or overvoltage
- COLLISION PREVENTION ASSIST switched on in the instrument cluster (up to 30.11.2018)
- COLLISION PREVENTION ASSIST switched on in the head unit (as of 01.12.2018)
- Engine running or drivetrain operational
- Vehicle is not in backward movement
- Dirt and function test of the radar sensor in the COLLISION PREVENTION ASSIST controller unit completed successfully
Model 190 up to 11/30/18
with code 258 (COLLISION PREVENTION ASSIST)
COLLISION PREVENTION ASSIST is released manually through the operation level in the instrument cluster. The IC transmits the respective status via the user interface CAN, AMG Gateway control unit, chassis CAN 2, the front SAM control unit and chassis CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
Model 190 as of 12/1/18
with code 258 (COLLISION PREVENTION ASSIST)
The COLLISION PREVENTION ASSIST is enabled manually via the operation level in the head unit. The head unit sends the corresponding status via the user interface CAN, the AMG gateway control unit, and suspension CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
The ME-SFI [ME] control unit sends the signal "Engine running" or the "Drivetrain operational" signal via the drive train CAN, powertrain control unit and chassis CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
The COLLISION PREVENTION ASSIST controller unit performs a dirt and function test after every engine start. The function test requires an object to be located in the detection area of radar sensors which use this object as a reference value. If malfunctions are established or if no function test is possible, the COLLISION PREVENTION ASSIST PLUS cannot be activated.
COLLISION PREVENTION ASSIST, general
The COLLISION PREVENTION ASSIST continuously checks the following distance to the vehicle driving directly ahead and warns the driver visually and acoustically of possible collisions (for example a rear-end collision) with other vehicles. In a collision-critical situation, the COLLISION PREVENTION ASSIST initiates autonomous brake application.
To do this the COLLISION PREVENTION ASSIST controller unit evaluates the traffic situation in front of the vehicle, the route immediately in front as well as the driver activity and constantly determines the risk potential of a possible collision. Corresponding warnings are output in a vehicle speed range between 7 and 250 km/h. If the driver reacts to the warning tone and applies the brakes, he or she is supported by the adaptive Brake Assist. This calculates the required brake force amplification according to the situation. Autonomous partial braking is also initiated if there is no reaction from the driver to the warnings. In this way a possible collision can be avoided or at least its consequences can be reduced.
The following assembly parts are integrated in the COLLISION PREVENTION ASSIST controller unit:
- Radar sensor
- Control unit
Model 190
with code 258 (COLLISION PREVENTION ASSIST)
with code 299 (PRE-SAFE® system)
The COLLISION PREVENTION ASSIST supports the safety system PRE-SAFE®.
The following presentation shows the detection range of the integral radar sensor.
Illustration of the principle of the detection range of the radar sensor
The COLLISION PREVENTION ASSIST comprises the following subfunctions:
- Distance warning
- Brake force boosting
- Autonomous brake application
Distance warning
Apart from data from the radar sensor, the COLLISION PREVENTION ASSIST controller unit also evaluates the following variables:
- Direction of travel and vehicle speed
- Acceleration/yaw rate
- Steering wheel angle
- Driver activity:
- Accelerator pedal position
- Status of brake pedal
- Setting the turn signal lights (turn signaling):
Direction of travel and vehicle speed :
The direction of travel is defined using the wheel rotation direction. The vehicle speed is calculated on the basis of the wheel speeds. The Electronic Stability Program control unit transmits appropriate information via the chassis CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
Acceleration/yaw rate :
The acceleration/turn rate is detected by the yaw rate sensor for lateral and longitudinal acceleration. The turn rate sensor for lateral and longitudinal acceleration transmits appropriate values via the driving dynamics CAN, Electronic Stability Program control unit and chassis CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
Steering wheel angle :
The data from the steering wheel angle sensor serve to test the plausibility of the turn rate detected by the yaw rate sensor for lateral and longitudinal acceleration.
Up to 30.11.2018
The steering wheel angle sensor detects/records the steering wheel angle. The steering column tube module control unit reads in the signals of the steering wheel angle. sensor directly and transmits information to the steering wheel angle via chassis CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
As of 01.12.2018
The steering wheel angle sensor detects/records the steering wheel angle The steering column tube module control unit reads in the signals of the steering wheel angle sensor directly and sends information on the steering angle via AMG FlexRay, the AMG gateway control unit, and suspension CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
Accelerator pedal position :
The ME-SFI [ME] control unit sends information about the accelerator pedal position via the drive train CAN, powertrain control unit and chassis CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
Status of brake pedal
The Electronic Stability Program control unit transmits the status of the brake pedal via chassis CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
Setting the turn signal lights (turn signaling) :
Up to 30.11.2018
The steering column tube module control unit directly reads in the switch position of the combination switch and transmit this via chassis CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
As of 01.12.2018
The steering column tube module control unit reads in the switch position of the combination switch directly and sends it via AMG FlexRay, the AMG gateway control unit, and suspension CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
The COLLISION PREVENTION ASSIST controller unit calculates the distance from the obstacle and the time up to a possible collision. The COLLISION PREVENTION ASSIST controller unit differentiates here between a static (without code 494 (USA version)) and a collision-critical distance warning.
Static distance warning (except code 494 (USA version)) :
Output of the static distance warning takes place purely optically.
If the distance from the vehicle directly ahead is undershot for 0.8 s in flowing traffic and this critical distance is maintained for longer than 3 s, (e.g. at a speed of 100 km/h, distance of approx. 22.2 m), the COLLISION PREVENTION ASSIST controller unit sends the request to output a warning.
Up to 30.11.2018
The COLLISION PREVENTION ASSIST controller unit sends the request to output the warning via suspension CAN 1, the front SAM control unit, suspension CAN 2, AMG gateway control unit, and user interface CAN to the instrument cluster. The instrument cluster reacts by actuating the DISTRONIC warning lamp.
As of 01.12.2018
The COLLISION PREVENTION ASSIST controller unit sends the request to output the warning via suspension CAN 1, the AMG gateway control unit, and the user interface CAN to the instrument cluster. The instrument cluster reacts by actuating the DISTRONIC warning indicator.
Collision critical distance warning :
Output of the collision-critical distance warning takes place optically and acoustically.
If an obstacle in the detection range of the radar sensor is classified as accident-critical (a collision will occur within 2. 6 s), the COLLISION PREVENTION ASSIST controller unit sends the request to output the warning.
Up to 30.11.2018
The COLLISION PREVENTION ASSIST controller unit sends the request to output the warning via suspension CAN 1, the front SAM control unit, suspension CAN 2, AMG gateway control unit, and user interface CAN to the instrument cluster. The instrument cluster then actuates the DISTRONIC warning lamp and the instrument cluster speaker (intermittent warning tone) directly.
As of 01.12.2018
The COLLISION PREVENTION ASSIST controller unit sends the request to output the warning via suspension CAN 1, the AMG gateway control unit, and the user interface CAN to the instrument cluster. The instrument cluster then actuates the DISTRONIC warning display and the instrument cluster speaker (intermittent warning tone) directly.
The warning output cannot be acknowledged. Take-back of the warning only occurs if the situation has been defused.
For output of the warning the COLLISION PREVENTION ASSIST controller unit also takes the driver activity and the route directly ahead into account (apart from the vehicle speed and the distance to an vehicle moving directly ahead). The driver activity is detected, for example, through modifications of the accelerator pedal position, through actuation of the turn signal lights or through pressing the brake pedal. The route ahead is defined over the yaw rate, the steering wheel angle and the direction of travel.
Due warning of stationary obstacles is given only in the vehicle speed range of approx. 7 to 72 km/h.
System limits:
The collision-critical warning is not output for the following events:
- Collisions with animals
- Collisions with oncoming vehicles
- Collisions with cross traffic
- Collisions in curves
Warning display in the instrument cluster, up to 30.11.2018
Warning display in the instrument cluster, as of 01.12.2018
Brake force boosting
If the driver then reacts to the collision-critical distance warning with emergency braking, the Brake Assist System provides support for the best possible utilization of the braking distance to the obstacle. Brake force boosting is available at a vehicle speed range of over 7 km/h.
The appropriate brake force boosting for the situation can react up to a vehicle speed of approximately 250 km/h to objects that were detected at least once as driving during the observation period. The appropriate brake force boosting for the situation reacts to obstacles up to a vehicle speed of approximately 70 km/h.
The COLLISION PREVENTION ASSIST controller unit evaluates the data from the radar sensor and permanently calculates the required brake force.
The emergency braking is defined over the speed and the strength with which the brake pedal is actuated.
The actuation speed and the actuation forces are detected by front axle brake pressure sensor. The Electronic Stability Program control unit reads in the signals from the front axle brake pressure sensor directly, calculates the braking torque requested by the driver and sends this information via chassis CAN 1 to the COLLISION PREVENTION ASSIST controller unit.
In the event of emergency braking, the COLLISION PREVENTION ASSIST controller unit sends the required brake force via chassis CAN 1 to the Electronic Stability Program control unit, which actuates the hydraulic brake pressure via the traction system hydraulic unit.
Model 190
with code 258 (COLLISION PREVENTION ASSIST)
with code 299 (PRE-SAFE® system)
The PRE-SAFE® function evaluates the braking torque currently being requested and, if necessary, initiates corresponding measures.
If a collision is unavoidable, occupant protection measures are taken in addition to intervention by the brake system.
If there is no actuation or the intensity of actuation of the brake pedal by the driver considerably decreases, the brake boost on the driver braking is reduced and the Brake Assist System is also deactivated. The Brake Assist System will also be deactivated if the driver presses the accelerator pedal.
Additional function requirements for autonomous brake application
- Vehicle speed of 7 to 105 km/h (for obstacles directly ahead) or from 7 to 50 km/h (for stationary obstacles)
Autonomous brake application
If the driver fails to react to an accident-critical situation to the warning, the COLLISION PREVENTION ASSIST controller unit initiates autonomous brake application and a reduction in engine torque. The COLLISION PREVENTION ASSIST controller unit calculates the necessary braking torque (maximum deceleration approx. 6 m/s2 ) taking into account the following variables:
- Speed difference relative to the vehicle or obstacle
- Distance from vehicle or obstacle
The COLLISION PREVENTION ASSIST controller unit sends the appropriate request to increase the braking torque and to reduce the engine torque via chassis CAN 1 to the Electronic Stability Program control unit. The Electronic Stability Program control unit evaluates the incoming requests, actuates the traction system hydraulic unit directly, and sends the request to reduce engine torque via chassis CAN 1, powertrain control unit and engine CAN to the ME-SFI [ME] control unit.
If the driver then reacts to the autonomous braking and brakes, the Brake Assist provides support for the best possible utilization of the braking distance to the obstacle.
Model 190
with code 258 (COLLISION PREVENTION ASSIST)
with code 299 (PRE-SAFE® system)
If a collision is unavoidable, occupant protection measures are taken in addition to intervention by the brake system.
| Electrical function schematic for COLLISION PREVENTION ASSIST | Model 190 up to 11/30/18 with code 258 (COLLISION PREVENTION ASSIST) | PE30.30-P-2058-97HBA | |
| Model 190 as of 12/1/18 with code 258 (COLLISION PREVENTION ASSIST) | PE30.30-P-2058-97HBB | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998RR |