BAS PLUS, function - GF30.30-P-3310CAM
MODEL 207.3/4 as of model year 2014 with CODE 268 (Brake Assist System Plus)
MODEL 207.3/4 as of model year 2014 with CODE 269 (Brake Assist PLUS with Cross-Traffic Assist (BAS+Q)
Function requirements, general
- No undervoltage or overvoltage
- "BasExtd_Avl" (for code 268 (Brake Assist PLUS)) programmed in the front SAM control unit
- "BasPlusQ_Avl" (for code 269 (Brake Assist PLUS crossing traffic (BAS+Q)) programmed in the front SAM control unit
- System fault-free (no faults reported by function-specific error management)
- Engine running or drivetrain operational
- Radar sensor system soiling and function test for the 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 DISTRONIC (DTR) sensors on the front bumper perform a soiling and function test after each engine start to securing perfect functioning. The function test requires an object in the respective detection area, and is used as a reference object. If a malfunction is detected or if there are no objects in the detection range (for the function test), Brake Assist System PLUS (BAS PLUS) cannot be activated. The radar sensors control unit receives the signals from the DISTRONIC (DTR) sensors on the front bumper via the radar CAN 1 and sends them via 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 chassis FlexRay to the radar sensors control unit.
- Soiling and function test of the MFK stereo completed successfully (for code 269 (BAS PLUS cross traffic (BAS+Q)))
- Electronic Stability Program (ESP®) not switched to passive mode
- No active ESP® intervention recognized (vehicle not in sliding movement)
- Gear range "D" engaged (vehicle not in backward movement)
- Vehicle speed from v = 7 to 250 km/h
- Standstill control, enable issued (driver door/driver belt buckle and front passenger door closed)
The front SAM control unit transmits the signal "BAS PLUS" and "BAS PLUS cross traffic (BAS+Q)" via the chassis CAN 1, chassis gateway control unit and chassis FlexRay to the radar sensors control unit and to the MFK stereo.
The CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or "Drivetrain operational" signal to the radar sensors control unit via the chassis CAN 1, the chassis gateway control unit and chassis FlexRay.
The Electronic Stability Program control unit transmits the status of the ESP® via the chassis CAN 1, chassis gateway control unit and chassis FlexRay to the radar sensors control unit.
The acceleration/yaw rate is detected by the yaw 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 transmits this via the chassis CAN 1, chassis gateway control unit and chassis FlexRay to the radar sensors control unit:
The fully integrated transmission control unit transmits information about the engaged gear range to the radar sensors control unit via the drive train CAN, CDI control unit or ME-SFI [ME] control unit, chassis CAN 1, chassis gateway control unit and chassis FlexRay.
The vehicle speed is calculated from the wheel speeds, the direction of travel is defined by the wheel rotation direction. The Electronic Stability Program control unit sends this information to the radar sensors control unit via chassis CAN 1, the chassis gateway control unit and chassis FlexRay.
BAS PLUS, general
BAS PLUS can not only support the driver in avoiding rear-end collisions in linear traffic or in minimizing its consequences, but can use the new Intersection Assist function as support in case of a risk of collisions with the cross traffic at intersections. The pedestrian detection in the BAS PLUS system can prevent a collision with pedestrians or reduce the severity of the impact. If the driver does not actuate the brake hard enough in a hazardous situation, BAS PLUS automatically increases the brake pressure to ensure effective emergency braking, if necessary up to a full stop. The brake application which is metered according to the situation is also makes the greatest possible braking distance available for the traffic to the rear.
In a vehicle speed range of v = 7 to 250 km/h the BAS PLUS is activated in a possibly dangerous situation. BAS PLUS is only activated for stationary obstacles, pedestrians and crossing vehicles when the vehicle speed is a maximum of v = 72 km/h. The controlling takes place by the radar sensors control unit, which actively intervenes in the brake system.
Function sequence for BAS PLUS
BAS PLUS assumes that the following conditions are given when implementing the function:
- Object detection in longitudinal direction
- Detection of objects crossing the lane (for code 269 (Brake Assist system PLUS crossing traffic (BAS+Q)))
- Detection of stationary and slow-moving pedestrians
Object detection in longitudinal direction:
Objects in the longitudinal direction are detected by the front long range radar sensor.
The front long range radar sensor monitors the area in front of the vehicle up to a distance of s = 200 m within a corridor of ∠ = 18°. Objects up to a distance of s = 0 to 60 m are detected in a corridor of ∠ = 60°.
The front long range radar sensor operates according to the pulse modulated Doppler radar principle, which enables the distances and speeds of individual objects (e.g. vehicles) to be measured independently of each other.
The front long-range radar sensor sends corresponding information via the chassis FlexRay to the radar sensors control unit.
Up to a distance of s = 30 m, objects are additionally detected by the front bumper DISTRONIC (DTR) radar sensor (short range radar sensor system). The object detection by the short range radar sensor system simply serves to allow plausibility checking.
The DISTRONIC (DTR) sensors on the front bumper transmit information via radar CAN 1 to the radar sensors control unit.
Detection of objects crossing the lane (for code 269 (Brake Assist system PLUS crossing traffic (BAS+Q)))
Crossing objects and pedestrians are detected in the vehicle speed range of v = 7 to 72 km/h depending on their condition (height, width) and their closing speed by the front long range radar sensor and the stereo multifunction camera.
The stereo multifunction camera is located in the upper area of the windshield and supplies the following data:
- Relative position of an object and pedestrians crossing the driving lane corridor
- Side closing speed
The stereo multifunction camera consists of two high-resolution mono cameras and an integrated control unit for evaluation and a plausibility check of the supplied picture data. The laterally offset location of the two mono cameras creates a difference in perspective (parallax displacement) between the left and right optical path. The distance to the detected object and other variables such as the height, size and circumference or the speed of motion can be evaluated on the basis of the differences between the image data.
The image data from the two mono cameras is prepared by the integrated control unit and sent via chassis FlexRay to the radar sensors control unit. The radar sensors control unit compares the image data with the signals from the radar sensor system.
The following traffic situations delineate the limits of the BRAKE ASSIST SYSTEM PLUS CROSS TRAFFIC:
- Objects such as walls or trees prevent the detection of any objects approaching from the side
- Contours of larger vehicles overlap the contours of smaller vehicles
- Vehicles approaching from the side at high speed
Detection of stationary and slow-moving pedestrians Pedestrians located in an area at the side of the lane can be detected in a vehicle speed range of v = 0 to 72 km/h.
Persons are detected by the stereo multifunction camera and the front long range radar sensor.
The radar sensor system detects people or objects, and it can conduct positioning within a defined range - dependent on the distance from the person or object involved and the vehicle speed. It is not however capable of performing exact position finding in a transverse direction. This is why redundant detection by the stereo multifunction camera is required.
If BAS PLUS detects a threat of collision with a vehicle or a person, the driver is supported during braking.
At a speed of < 30 km/h:
- If the brake pedal is actuated, BAS PLUS is activated. BAS PLUS provides a brake boost at the latest possible point in time.
At a speed of < 30 km/h:
- If the brake pedal is actuated hard (emergency braking), BAS PLUS automatically increases the brake pressure to a value adapted to the traffic situation.
The hazard braking is defined over the actuation speed and the actuation strength with which the brake pedal is actuated.
The Electronic Stability Program control unit the braking request of the driver about the increasing brake pressure in the master brake cylinder. The brake pressure is registered by the 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 the chassis FlexRay to the radar sensors control unit. The radar sensors control unit uses the data from the front long range radar sensor in combination with that from the front bumper radar sensors and the stereo multifunction camera, calculates the required braking torque and transmits the request via chassis FlexRay, chassis gateway control unit and chassis CAN 1 to the Electronic Stability Program control unit, which then directly actuates the traction system hydraulic unit.
If there is no actuation or the intensity of actuation of the brake pedal by the driver decreases, the brake boost is reduced to the driver braking level and the BAS PLUS function is deactivated. If the driver presses the accelerator pedal, the BAS PLUS is also deactivated.
| Electrical function schematic for BAS PLUS | PE30.30-P-2063-97EAA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998CAM |