Brake Assist System/BAS Plus, Function - GF30.30-P-3310RF

Model 205 

up to model year 2019 

with code 268 (Brake Assist System Plus) 

Model 205 

up to model year 2019 

with code 269 (Brake Assist PLUS with Cross-Traffic Assist (BAS+Q) 

Model 253 (except 253.99) 

up to model year 2020 

with code 268 (Brake Assist System Plus) 

Model 253 (except 253.99) 

up to model year 2020 

with code 269 (Brake Assist PLUS with Cross-Traffic Assist (BAS+Q) 

Courtesy of MERCEDES-BENZ USA

Function requirements, general 

• No undervoltage or overvoltage
• "BasExtd_Avl" (with code 268 (Brake Assist PLUS)) programmed in electronic ignition lock control unit:

  The electronic ignition lock control unit sends the signal "Brake Assistant PLUS" to the radar sensors control unit and to the stereo multifunction camera via chassis FlexRay.

• "BasPlusQ_Avl" (with code 269 (Brake Assist PLUS crossing traffic (BAS+Q)) programmed in electronic ignition lock control unit:

  The electronic ignition lock control unit sends the signal "BAS PLUS Cross Traffic" to the radar sensors control unit and to the stereo multifunction camera via chassis FlexRay.

• System fault-free (no faults detected by function-specific error management)
• Engine running or drivetrain operational:

  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 drive train CAN, powertrain control unit and chassis FlexRay.

• Radar sensor system soiling and function test for the radar sensor system completed successfully:

  Object recognition (e.g. vehicle moving directly ahead) via the radar sensor system is based on the radar measuring procedure.

  The front long range radar sensor and the front bumper radar sensors run a contamination and function test after each engine start to ensure that they are functioning correctly. The function test requires an object in the respective detection area that is used as a reference object. If a malfunction is established or if there are no objects in the detection area, the BAS PLUS cannot be activated.

  The radar sensors control unit receives the signals of the front bumper radar sensors via 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 chassis FlexRay to the radar sensor control unit.

• Stereo multifunction camera soiling and function test:

  The stereo multifunction camera performs a soiling and function test to ensure proper operation after each engine start. The function test requires an object in the respective detection area that is used as a reference object. If a malfunction is established or if there are no objects in the detection area, the BAS PLUS cannot be activated. The stereo multifunction camera sends the lane data via the chassis FlexRay to the radar sensors control unit.

• Electronic Stability Program (ESP®) not switched to passive mode:

  The Electronic Stability Program control unit sends the status of the Electronic Stability Program® via the suspension FlexRay to the radar sensors control unit.

• No active ESP® intervention recognized (vehicle not in sliding movement)
• Gear range "D" engaged (vehicle not in backward movement):

  The fully integrated transmission control unit sends information about the selected gear range via drive train CAN, powertrain control unit and suspension FlexRay to the radar sensors control unit.

• Vehicle speed of v = 7 to 250 km/h:

  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 about wheel speed and wheel rotation direction to the radar sensors control unit via chassis FlexRay.

• Standstill control, enable issued (driver door/driver belt buckle and front passenger door closed):

  The acceleration/yaw rate is detected by the acceleration sensor integrated into the Supplemental Restraint System control unit. The supplemental restraint system control unit sends the corresponding values via the vehicle dynamics CAN to the Electronic Stability Program control unit. The Electronic Stability Program control unit transmits these via the suspension FlexRay to the radar sensors control unit.

BAS PLUS, general 

BAS PLUS can support the driver in avoiding rear-end collisions or minimizing their consequences not just in longitudinal traffic. Thanks to the new intersection assist function, BAS PLUS can also provide support in the event of impending collisions with the cross traffic at intersections (with code 269 (Brake Assist System PLUS cross traffic (BAS+Q))). The pedestrian recognition in the BAS PLUS system can avoid a collision with pedestrians or reduce the severity of the impact.

If the driver operates the brake too tentatively, BAS PLUS automatically increases the brake pressure, if necessary up to maximum full-stop braking. 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 the vehicle speed range of v = 7 to 250 km/h, BAS PLUS is activated in a potentially hazardous 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 (with code 269 (Brake Assist system PLUS crossing traffic (BAS+Q)))
• Detection of stationary and slow-moving pedestrians

Object detection in longitudinal direction:

Object detection long range takes place by the long range radar sensor at the front.

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 concept, 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.

From a distance of s = 30 m object detection is also performed by the front bumper radar sensors (short range radar sensor system). The object detection by the short range radar sensor system simply serves to allow plausibility checking.

The front bumper radar sensors send information via the radar CAN 1 to the radar sensors control unit.

Detection of objects crossing the lane (with code 269 (Brake Assist system PLUS crossing traffic (BAS+Q))):

Crossing objects and pedestrians are detected in a vehicle speed range of v = 7 to 72 km/h dependent on their nature (height, width) and their closing speed by front long range radar sensors and the stereo MFK.

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 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 show the limits of the BRAKE ASSIST SYSTEM PLUS CROSS TRAFFIC (BAS+Q):

• Objects such as walls or trees prevent acquisition of any objects approaching from the side.
• Contours of larger vehicles overlap 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.

Pedestrians are detected by the stereo multifunction camera and the front long range radar sensor.

The radar sensor system detects pedestrians and objects and can determine their position within a defined area - dependent on the distance from the pedestrians or the object and on the vehicle speed. It is not, however, capable of performing exact positioning in the 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 pedestrian, the driver is supported during braking.

At a speed of < 30 km/h:

• If the brake pedal is actuated, BAS PLUS is activated. The brake force boosting by BAS PLUS takes place at the last 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 emergency 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 directly reads in the signal from the front axle brake pressure sensor, 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 long range radar sensor in combination with that from the front bumper radar sensor and the stereo MFK, calculates the required braking torque and transmits the request via the chassis FlexRay to the Electronic Stability Program control unit which reacts by directly activating the traction system hydraulic unit.

If there is no actuation occurs or the intensity of actuation of the brake pedal by the driver reduces, the brake servo assistance is reduced to the driver braking level and the BAS PLUS function is deactivated. If the driver presses the accelerator pedal, BAS PLUS is also deactivated.

Model 205.012/047/147/212/247

up to model year 2019

with code 268 (Brake Assist System Plus)

Model 205.012/047/147/212/247

up to model year 2019

with code 269 (Brake Assist PLUS with Cross-Traffic Assist (BAS+Q)

Model 253.354/954

up to model year 2020

with code 268 (Brake Assist System Plus)

Model 253.354/954

up to model year 2020

with code 269 (Brake Assist PLUS with Cross-Traffic Assist (BAS+Q)

The kinetic energy is converted within defined limits into electrical energy (regenerative braking). If the requested braking torque exceeds the deceleration through recuperation (for example in a case of a emergency braking), the Electronic Stability Program control unit additionally actuates the traction system hydraulic unit and therefore the service brake.

	Electrical function schematic for BAS PLUS		PE30.30-P-2063-97FBA
	Overview of system components for driver assistance systems	Model 205 up to model year 2019 with code 268 (Brake Assist System Plus) Model 205 up to model year 2019 with code 269 (Brake Assist PLUS with Cross-Traffic Assist (BAS+Q) Model 253 (except 253.99) up to model year 2020 with code 268 (Brake Assist System Plus) Model 253 (except 253.99) up to model year 2020 with code 269 (Brake Assist PLUS with Cross-Traffic Assist (BAS+Q)	GF54.00-P-9998RF