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Distronic Plus Incl. BAS Plus And Pre-Safe Brake, Function - GF30.30-P-0006GR

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MODEL 166 up to model year 2016 with CODE 233 (DISTRONIC PLUS) 

G12082579

Function requirements, general 

IMPORTANT The standstill control function is described in detail in the separate description "Adaptive Brake".

The Electronic Stability Program control unit transmits the status of the standstill control via chassis CAN 1 to the video and radar sensor system control unit.

DISTRONIC PLUS incl. BAS PLUS (BAS PLUS) and PRE-SAFE® brake, general points 

The DISTRONIC PLUS regulates the speed and distance relative to the vehicle driving in front in a vehicle speed range of v = 0 to 200 km/h and v = to km/h automatically according to the driver's request. The PRE-SAFE® brake function constantly determines the hazard potential for a rear-end collision and, in accident-critical situations, initiates corresponding measures to minimize the consequences of the collision. Furthermore, there is a distance warning function contained therein which advises the driver about a vehicle driving immediately ahead which is too close. An optical and acoustic warning is issued before any possible collisions with vehicles or stationary obstacles on the vehicle's own lane.

If the driver reacts to the collision critical warning with an emergency braking maneuver, the BAS PLUS feature provides support. The required brake boosting effect for this is calculated according to the situation. This means that the brakes are automatically applied as intensively as required (max. approx. a = 10 m/s2 ). In doing this the threat of a collision can be reduced or at least the severity of the accident can be reduced. If the driver does not react to the warning, the PRE-SAFE® brake function brakes the vehicle autonomously and can then mitigate the effects of a possible collision.

IMPORTANT The PRE-SAFE® brake function also supports the PRE-SAFE® safety concept. The function PRE-SAFE® is described in the separate function description "PRE-SAFE® function".

IMPORTANT The following partial functions of the DISTRONIC PLUS are described in the separate function description "CC (TPM) function:

The following graphics illustrate the function of the DISTRONIC PLUS incl. BAS PLUS and PRE-SAFE® brake:

Detection area of the radar sensor system 

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Illustration of the principle of the functions BAS PLUS and PRE-SAFE® brake, shown on model 221 

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Operation of the DISTRONIC PLUS takes place over the cruise control lever.

Design of the cruise control lever 

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IMPORTANT The distance to the vehicle driving immediately ahead is displayed in the multifunction display for t = 5 s after actuation of the CC lever. Through selection of the operating level "DISTRONIC PLUS" in the menu "Assistance" the distance graphic is shown permanently. Display of the distance graphic can be switched on or off independently of the activity of the automatic distance control. The distance to the vehicle driving immediately ahead can be set over the DISTRONIC control in seven stages between t = 1.0 and 2.0 s.

The control takes place by the video and radar sensor system control unit. The video and radar sensor system control unit intervenes actively in the engine management as well as in the brake system to implement the functions. The acoustic warnings are emitted by the warning buzzer in the IC. The optical note and warning messages are issued over the multifunction display.

The video and radar sensor system control unit evaluates the input factors and transmits an appropriate request for controlling the functions DISTRONIC PLUS, BAS PLUS and PRE-SAFE® brake via the following CANs:

The video and radar sensor system control unit evaluates the following input factors: 

Operating condition for engine/drivetrain:

The signal "engine running" or "drivetrain operational" is sent by the CDI control unit or the ME-SFI [ME] control unit via chassis CAN 1 to the video and radar sensor system control unit.

Engaged gear range:

The fully integrated transmission control unit sends the information on the gear range via drive train CAN, CDI control unit or ME-SFI [ME] control unit and chassis CAN 1 to the video and radar sensor system control unit.

Parking brake status

The electric parking brake control unit sends the status of the parking brake via chassis CAN 1 to the video and radar sensor system control unit.

ESP® status:

The Electronic Stability Program control unit sends the status of ESP® to the video and radar sensor system control unit via chassis CAN 1.

Engine drive torque:

The CDI control unit or the ME-SFI [ME] control unit sends information about the currently available engine drive torque via chassis CAN 1 to the Electronic Stability Program control unit which evaluates this appropriately and transmits it via chassis CAN 1 to the video and radar sensor system control unit.

Braking torque:

Information about the currently applied braking torque is transmitted by the Electronic Stability Program control unit via chassis CAN 1 to the video and radar sensor system control unit.

Acceleration/yaw rate:

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 sensor transmits the values for acceleration and yaw rate via the dynamics CAN, Electronic Stability Program control unit and chassis CAN 1 to the video and radar sensor system control unit.

IMPORTANT On safety and comfort grounds the maximum (positive) acceleration of the automatic distance control is limited to about a = 2.5 m/s2 . It behaves in reverse proportion to the vehicle speed. This means that smaller accelerations are permitted for an increasing vehicle speed.

Driver request via the cruise control lever:

The driver request over the CC lever are directly read in by the steering column tube module control unit. The steering column tube module control unit transmits the control signals of the CC lever via the chassis CAN 1 to the video and radar sensor system control unit.

The driver request "Overtake":

The steering column tube module control unit directly reads in the switch position of combination switch and transmits this via chassis CAN 1 to the video and radar sensor system control unit.

Driver request via menu settings in the IC:

The following settings can be selected over the menu settings in the IC:

The instrument cluster sends the corresponding status via chassis CAN 2, electronic ignition lock control unit and chassis CAN 1 to the video and radar sensor system control unit.

Vehicle speed/direction of travel/acceleration

The vehicle speed is calculated on the basis of the wheel speeds. The direction of travel is defined by the wheel rotation direction, the acceleration by the increase in the wheel rotation speed. The wheel speeds and the wheel rotation direction are recorded by the rpm sensors. The Electronic Stability Program control unit directly reads in the signals of the rpm sensors and sends them via chassis CAN 1 to the video and radar sensor system control unit.

GPS signals:

The navigation system of the COMAND controller unit or the radio, in combination with the navigation module adapted via telematics CAN, sends the GPS signals via interior CAN, electronic ignition lock control unit and chassis CAN 1 to the video and radar sensor system control unit.

Steering wheel angle:

The steering angle is recorded by the steering wheel angle sensor. The steering column tube module control unit reads in signals from the steering wheel angle sensor and transmits the data via chassis CAN 1 to the video and radar sensor system control unit.

Object recognition in the short range:

The short range radar sensor system in the front bumper operates in the 24 GHz frequency range (model 166.0 up to 30.11.2012, model 166.8 up to 30.06.2013) or in the 25 GHz frequency range (model 166.0 as of 01.12.2012, model 166.8 as of 01.07.2013) with a maximum range of s = 30 m and is integrated in the following components:

IMPORTANT This is switched off automatically in countries in which the 24 GHz radar sensor system is not approved.

The detection angle of the short range radar sensors is a maximum of ∠ = 130°. A precise angle can be determined within a detection zone of ∠ = 60° and up to ∠ = 130° only after detection of the objects. The DISTRONIC sensors send the corresponding information via sensor CAN with the video and radar sensor system control unit.

Object recognition in the long range:

The long range radar is integrated in the DISTRONIC controller unit and operates in the 77 GHz frequency range. With its detection angle of ∠ = 18°, the long range radar covers the front area of the vehicle at a length of s = 0 up to 200 m. The range s = 0 m to s = 60 m in front of the vehicle is detected for an angle of ∠ = 60°.

The DISTRONIC controller unit performs a soiling and function test to ensure proper operation after each engine start. The function test requires an object in the detection range of the long range radar which is used as a reference value for the function test by the DISTRONIC controller unit. DISTRONIC PLUS cannot be activated if a malfunction is established or if there are no objects (for the function test) in the detection range of the long range radar. The DISTRONIC PLUS controller unit sends the corresponding information via vehicle dynamics CAN with the video and radar sensor system control unit. Brake pedal position:

Operation of the brake pedal is registered by the brake lights switch. The Electronic Stability Program control unit directly reads in the status of the brake lights switch and transmits these via chassis CAN 1 to the video and radar sensor system control unit.

Accelerator pedal position:

Operation of the accelerator pedal is registered by the accelerator pedal sensor. The CDI control unit or the ME-SFI [ME] control unit directly reads in the signals from the accelerator pedal sensor and sends this via chassis CAN 1 to the video and radar sensor system control unit.

The video and radar sensor system control unit emits the following initial parameters (requests): 

Engage targeted gear:

The video and radar sensor system control unit transmits an appropriate request via chassis CAN 1 to the ESP control unit. The Electronic Stability Program control unit internally evaluates this request as well as further driving dynamics requests internally and transmits them, according to requirements via chassis CAN 1, the CDI control unit or the ME-SFI [ME] control unit and drive train CAN to the fully integrated transmission control unit. This is however simply to be understood as a switching recommendation. Downshifting or upshifting of the automatic transmission takes place autonomously by the fully integrated transmission control unit dependent on the current operating condition.

Raise/reduce engine torque:

The video and radar sensor system control unit transmits an appropriate request via chassis CAN 1 to the ESP control unit. The Electronic Stability Program control unit evaluates this request as well as further driving dynamics requests internally and forwards a corresponding request via chassis CAN 1 to the CDI control unit or to the ME-SFI [ME] control unit. The CDI control unit or the ME-SFI [ME] control unit implements this request.

Switch short range radar Off/On

The video and radar sensor system control unit switches the short range radar off and on again dependent on the protection zones around radio astronomy stations. The short range radar can also be switched off and on again manually over the menu "Vehicle settings" in the IC. The video and radar sensor system control unit transmits the respective request via the sensor CAN to the DISTRONIC (DTR) front bumper sensors.

IMPORTANT MODEL 166.0 as of 12/1/12 up to model year 2016

with CODE 233 (DISTRONIC PLUS)

MODEL 166.8 as of 7/1/13 up to model year 2016

with CODE 233 (DISTRONIC PLUS)

The radar sensor system is no longer automatically switched off. This is no longer necessary due to use of the reduced frequency band range of f = 24.25 to 25.65 GHz. Both the NATO band and the radio astronomy band are blanked out. Thus operation of the radar sensor system within the protected areas of the radio astronomy stations is permissible.

Raise/reduce braking torque:

The video and radar sensor system control unit transmits an appropriate request via chassis CAN 1 to the ESP control unit. The Electronic Stability Program control unit evaluates this request as well as further driving dynamics requests internally and actuates the traction system hydraulic unit accordingly. The braking torque is increased or reduced.

Emit warning tones, system or warning messages

The video and radar sensor system control unit sends the corresponding requests via chassis CAN 1, electronic ignition lock control unit, chassis CAN 2 to the instrument cluster. The IC actuates the warning buzzer integrated into the IC to output warning tones. The instrument cluster actuates the multifunction display or the DISTRONIC warning lamp directly to output system messages or warnings.

The DISTRONIC PLUS includes the following partial functions:

Additional function requirements for DISTRONIC PLUS 

IMPORTANT MODEL 166 up to model year 2016

with CODE 233 (DISTRONIC PLUS)

without CODE 494 (US version)

If the LED SPEEDTRONIC lights up, the DISTRONIC PLUS is deactivated and the function variable SPEEDTRONIC programmed.

Function sequence for DISTRONIC PLUS 

The description of the DISTRONIC PLUS function takes place, as an example, in the following chronological sequence:

The sequence can vary depending on the driver requests and the current traffic situation.

Activate DISTRONIC PLUS and drive off automatically 

The DISTRONIC PLUS can only be activated when stationary if a stationary vehicle is also detected by the radar sensor system. This displayed by the distance graphic in the multifunction display. If the vehicle driving immediately ahead moves off, the driver can press the accelerator pedal to confirm the automatic drive off function or alternatively actuate the "Resume from memory" switch on the CC lever. The brake pedal must not be pressed during this time. The vehicle subsequently starts off automatically, accelerates and follows the vehicle driving immediately ahead at the programmed distance up to the maximum speed to be set.

Technical implementation 

To do this the video and radar sensor system control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

Automatic distance control 

The automatic distance control can only be activated while driving (v < 30 km/h) if a vehicle driving in front was detected. If the vehicle driving immediately ahead brakes or accelerates, the DISTRONIC PLUS instigates the following measures for maintain the clearance:

The driver must press on the brake pedal if he sees that the instigated measures are not adequate, to avoid any possible collision. If the vehicle driving immediately ahead accelerates again, the engine torque is increased and the vehicle also accelerates. The driver also has the option to accelerate the vehicle (e.g. to overtake a vehicle). The automatic acceleration is put out of action for as long as the driver uses the accelerator pedal. The multifunction display shows the message "DISTRONIC passive". If the automatic distance control requires a higher acceleration than the driver prescribes, the driver request is overlaid by the request for automatic distance control.

Technical implementation 

To do this the video and radar sensor system control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

Change of driving lane (overtaking) 

For overtaking above a speed of v = 60 km/h (mph) the vehicle is also accelerated automatically. To do this the driver must initiate the overtaking maneuver by setting the turn signal. In as far as the automatic distance control is activated, the video and radar sensor system control unit recognizes the intention of the driver to overtake and accelerates the vehicle while taking account of the distance to the vehicle driving immediately ahead. The vehicle then accelerates up to set maximum speed (automatic speed control) after the overtaking maneuver in as far as there was no vehicle driving immediately ahead detected as a target object. If a vehicle driving immediately ahead is subsequently detected as a target object the automatic speed control function changes over again into the automatic distance control function.

The overtaking maneuver is broken off in the following situations:

Technical implementation 

To do this the video and radar sensor system control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

Automatic speed control 

If the vehicle is in active distance control and the vehicle driving in front accelerates above v = 200 km/h or removes itself from the detection area of the radar sensor system, the automatic distance control function switches over to the automatic speed control function.

IMPORTANT The automatic speed control is described in detail in the separate function description "CC (TPM) function".

Technical implementation 

To do this the video and radar sensor system control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

Passing through a radio astronomy protection zone 

On model 166.0 up to 30.11.2012, model 166.8 up to 30.06.2013, the short range radar sensor system is automatically switched off in certain protected areas around radio astronomy stations as a result of legal requirements on the 24 GHz radar system (short range radar, bandwidth: f = 5 GHz) in Western Europe.

When DISTRONIC PLUS is active, the message "Radar sensor system automatically switched off, see operator's manual" is shown on the multifunction display of the instrument cluster.

When the vehicle leaves the protected area, the short range radar sensor system is switched on again automatically.

For an activated DISTRONIC PLUS the message "DISTRONIC PLUS available again" is issued.

IMPORTANT MODEL 166.0 as of 12/1/12 up to model year 2016

with CODE 233 (DISTRONIC PLUS)

MODEL 166.8 as of 7/1/13 up to model year 2016

with CODE 233 (DISTRONIC PLUS)

The radar sensor system is no longer automatically switched off. This is no longer necessary due to use of the reduced frequency band range of f = 24.25 to 25.65 GHz. Both the NATO band and the radio astronomy band are blanked out. Thus operation of the radar sensor system within the protected areas of the radio astronomy stations is permissible. It is therefore also no longer necessary to have localization of the vehicle over GPS.

IMPORTANT The driver has the option to switch the short range radar sensor system off and on manually over the "Vehicle settings" menu in the instrument cluster. The instrument cluster sends the request "Switch short range radar off/on" via chassis CAN 2, electronic ignition lock control unit and chassis CAN 1 to the video and radar sensor system control unit.

Model 166.0 up to 30.11.2012, model 166.8 up to 30.06.2013:

If one seeks to manually switch on the short range radar sensors within a protected area, the message "Radar sensor system switched off automatically" is displayed in the multifunction display.

Technical implementation (model 166.0 up to 30.11.2012, model 166.8 up to 30.06.2013) 

The protected areas of the radio astronomy stations are stored in the form of Global Positioning System (GPS) coordinates in the video and radar sensor system control unit. The video and radar sensor system control unit evaluates the GPS signals and switches off the short range radar sensor array if necessary.

To do this the video and radar sensor system control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

Passing over roundabouts, T intersections and freeway exit lane 

The DISTRONIC PLUS function uses map data to adapt the system behavior to the following situations:

This means that if the vehicle driving immediately ahead leaves the detection area of the radar sensor system in one of the above-mentioned traffic situations then the current speed is maintained:

If no vehicle driving immediately ahead is detected afterwards, the vehicle accelerates or decelerates to the set specified speed.

IMPORTANT Since traffic situations are subject to alteration, the digital map data has to be regularly updated.

Technical implementation 

To do this the video and radar sensor system control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

Going back into a lane/person in the front regulation 

If the vehicle driving immediately ahead turns off and there is another vehicle in front, the system only switches over to the new target vehicle if it is moving. The system does not operate for stationary objects unless a preceding vehicle is tracked to a standstill. If while driving a vehicle turns in front within the safe distance to the vehicle driving immediately ahead, the distance to this new vehicle is regulated. If the vehicle is in automatic speed control and a vehicle tuns onto the lane driven in this vehicle is registered as the vehicle driving immediately ahead. If the distance to the moving in vehicle is below the value which was programmed, the DISTRONIC PLUS function brakes the vehicle. If the requested brake power is not adequate the driver must press the brake pedal.

IMPORTANT The negative acceleration (deceleration) over the traction system hydraulic unit is limited to 40% (about a = 4 m/s2 ) of the maximum possible brake power.

DISTRONIC PLUS is thereby deactivated. This process is signaled to the driver by outputting a notification tone over the warning buzzer and indication of a message in the multifunction display. The driver can subsequently reactivate the DISTRONIC PLUS.

Technical implementation 

To do this the video and radar sensor system control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

Automated Stop Vehicle 

For an active DISTRONIC PLUS the vehicle will follow the vehicle driving immediately ahead to standstill. Of the vehicle is stationary, it is secured against rolling away through activation of the service brake (safety strategy of standstill control).

IMPORTANT Securing the vehicle using the DISTRONIC PLUS function (standstill control) does not replace securing the vehicle for parking.

Technical implementation 

To do this the video and radar sensor system control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

The following traffic situations show the limits of DISTRONIC PLUS:

Obstacles and stationary vehicles

The DISTRONIC PLUS does not brake for obstacles or stationary vehicles which were not previously registered as the target object. If, for example, the detected vehicle turns off and there is an obstacle or a stationary vehicle behind it, no automatic intervention by the brake system occurs.

G07300324

Curves, curved entrances and exits:

The DISTRONIC PLUS can only provides limited detection of vehicles in curves. One's own vehicle can then brake unexpectedly or late.

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Vehicles moving across in front of one's own vehicle:

DISTRONIC PLUS may detect vehicles in cross traffic by mistake. For an activated distance control the vehicle can start off unintended, (e g. at a traffic light with cross-traffic).

G07300326

Displaced driving style:

DISTRONIC PLUS may not be able to detect vehicles driving displaced to one side. The distance to the vehicle in front becomes too small.

G10050075

Lane change by other vehicles:

The DISTRONIC PLUS does not yet detect the vehicle moving into the lane. The distance to the vehicle moving into the lane becomes too small.

G10050076

Narrow vehicles:

The DISTRONIC PLUS does not recognize the vehicle driving immediately ahead on the driving lane because it is too small. The distance to the vehicle in front becomes too small.

G10050077

Function sequence for PRE-SAFE® brake and BAS PLUS 

The BAS PLUS and the PRE-SAFE® brake assesses the traffic situation in front of the vehicle. In the following vehicle speed ranges emergency braking by the driver is supported by the function BAS PLUS or the vehicle is braked automatically in dangerous situations by the function PRE-SAFE® brake:

In the case of stationary obstacles, the BAS PLUS function or the PRE-SAFE® brake function is only activated if the vehicle's own vehicle speed is a maximum of v = 72 km/h. If a stationary object is detected in the lane by both the short and long range radar sensor systems (the lane is determined, amongst other things, by the steering wheel angle and vehicle speed, etc.), the BAS PLUS function and the PRE-SAFE® brake function are activated.

The description of the PRE-SAFE® brake function and the BAS PLUS is subdivided as follows:

BAS PLUS 

If the driver reacts in a dangerous situation with emergency braking (e.g. output of a collision-critical distance warning) he will be supported by the function BAS PLUS to use the braking distance to the obstacle in an optimal manner.

If there is no actuation by the driver of the brake pedal or the intensity of actuation of the brake pedal reduces, the brake boosting effect is reduced to the driver braking level and the BAS PLUS function is deactivated. The function BAS PLUS will also be deactivated if the driver presses on the accelerator pedal.

Technical implementation 

The emergency braking is defined over the actuation speed and the actuation strength with which the brake pedal is actuated. To do this, the video and radar sensor system control unit also uses the data from the radar sensor system and also calculates the necessary brake boosting effect while taking account of the distance and the closing speed to the obstacle.

IMPORTANT Parallel to this the function PRE-SAFE® integrated into the Electronic Stability Program control unit evaluates the current requested braking torque and instigates appropriate measures as necessary.

To do this the video and radar sensor system control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

PRE-SAFE® brake 

The PRE-SAFE® brake function includes a distance warning function to warn the driver of moving or stationary obstacles in his lane. The distance warning takes place in a vehicle speed range of v = 7 to 250 km/h. There is a differentiation here between a static and a collision-critical distance warning.

Static distance warning:

The static distance warning is triggered if the time interval between the system vehicle and vehicle driving immediately ahead is less than t = 0.8 s (e.g. in moving traffic). The DISTRONIC warning lamp lights up in the IC.

Collision critical distance warning:

If a moving obstacle in the detection range of the radar sensor system is classified as representing a critical accident situation (a collision within t < 2.6 s), the DISTRONIC warning lamp lights up and the warning buzzer emits an intermittent tone. The warning output is automatically switched off again when the situation is no longer critical and cannot be acknowledged during an active control.

IMPORTANT The distance warning function can be separately and independently activated and deactivated by the automatic distance control in the menu "PRE-SAFE® brake" of the instrument cluster. The distance warning is basically active for an active DISTRONIC PLUS. If the DISTRONIC PLUS is deactivated, actuation of the DISTRONIC warning lamp takes place by the function PRE-SAFE® brake.

Optical warning messages in instrument cluster when a safe distance is not maintained 

G12082589

If the driver does not react to the warnings, the PRE-SAFE® brake initiates autonomous partial braking. If the driver does not react to the partial braking and if the video and radar sensor system control unit calculates that the collision with the obstacle is unavoidable, the video and radar sensor system control unit instigates emergency braking for t = 1 s and thus reduces the possible consequences of an accident.

IMPORTANT Emergency braking is not triggered if the front passenger seat is occupied and the front passenger is not strapped in. To do this the video and radar sensor system control unit calculates the required braking torque while taking account of the driving dynamics input factors. The vehicle is braked according to this request.

Technical implementation 

To do this the video and radar sensor system control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

  Electrical function schematic for DISTRONIC PLUS incl. BAS PLUS and PRE-SAFE brake   PE30.30-P-2055-97NAA 
  Overview of system components for driver assistance systems   GF54.00-P-9998GR
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