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DISTRONIC PLUS, function - GF30.30-P-3300CAM

MODEL 207.3/4 as of model year 2014 with CODE 233 (DISTRONIC PLUS) 

Fig 1: DISTRONIC PLUS - Block Diagram
G10081657Courtesy of MERCEDES-BENZ USA

Function requirements, general 

IMPORTANT The standstill coordinator function is described in detail in the separate description "Adaptive Brake (ABR)".

Distronic PLUS, general 

IMPORTANT The units and values given in the following text for the speed must be assigned to the possible national versions. The details in "miles per hour (mph)" refer to vehicles with a miles indicator.

The DISTRONIC PLUS automatically regulates the speed and the distance to the vehicle driving immediately ahead in a vehicle speed range of v = 0 to 200 km/h and from v = 200 to 0 km/h (v = 0 to 120 mph and from v = 120 to 0 mph) according to the request from the driver. The controlling takes place using the radar sensors control unit. The radar sensors control unit intervenes to realize the DISTRONIC PLUS Active function in the engine timing as well as in the brake system.

The visual and acoustic warnings are issued on the instrument cluster

The individual DISTRONIC PLUS functions are switched on and off and they are controlled using the CRUISE CONTROL lever.

The menu settings in the instrument cluster can be used to switch the distance display on and off.

The radar sensors control unit is connected through the following Controller Area Networks (CAN) to the vehicle electronics:

The following subfunctions in the DISTRONIC PLUS are described in the separate "Cruise control (CC) Function" subfunction:

DISTRONIC PLUS requires the following input factors to implement the distance control and distance warning functions:

Object recognition in the long range by means of the long range radar sensors (77 GHz long range radar):

The front long range radar sensor covers the front area of the vehicle over a length of s = 60 to 200 m with an angular coverage of ∠ = 18°. The range s = 0 m to s = 60 m in front of the vehicle is covered for an angle of ∠ = 60°.

IMPORTANT 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.

Object detection in short range by the DISTRONIC (DTR) sensors on the front bumper (short range radar sensor system) (frequency range = 24.25 to 25.65 GHz):

The DISTRONIC (DTR) sensors on the bumper work according to the short pulse process with a f = 1.4 GHz band width for a maximum range of s = 30 m. The detection angle of the DISTRONIC (DTR) sensors on the front bumper is a maximum of ∠= 130°. Precise angular coverage is conducted in an angle sensing range of ∠= 80° and objects are only detected up to ∠ = 130°.

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 detection area of the respective radar sensor that is then used as a reference object for the function test. DISTRONIC PLUS cannot be activated if a malfunction is established or if there are no objects (for the function test) in the detection range. 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 - it sends the "Radar sensor system operational" status to the radar sensors control unit.

Operation:

Operation of the DISTRONIC PLUS takes place over the cruise control lever. The steering column tube module control unit directly reads in control signals from the CC lever and transmits them via the chassis CAN 1, the chassis gateway control unit and chassis FlexRay to the radar sensors control unit.

Design of the cruise control lever 

Fig 2: Overview Of Cruise Control Lever
G10081658Courtesy of MERCEDES-BENZ USA

Operation over the CRUISE CONTROL lever, vehicles without code (494) USA version 

Fig 3: Overview Of Cruise Control Lever - Vehicles Without Code (494) USA Version
G10081659Courtesy of MERCEDES-BENZ USA

Operation over the CRUISE CONTROL lever, vehicles with code (494) USA version 

Fig 4: Overview Of Cruise Control Lever - Vehicles With Code (494) USA Version
G10081660Courtesy of MERCEDES-BENZ USA

The radar sensors control unit evaluates the following input factors: 

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 chassis CAN 1, the chassis gateway control unit and chassis FlexRay.

Parking brake status

The front SAM control unit directly detects the status of the parking brake indicator switch and transmits the status of the parking brake to the radar sensors control unit via the chassis CAN 1, the chassis gateway control unit and the chassis FlexRay.

Engaged gear range/transmission mode:

The fully integrated transmission control unit transmits information about the engaged gear range and the transmission mode 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 front SAM control unit control unit directly reads in the status of the transmission mode button and transmits these via the chassis CAN 1, CDI control unit or ME-SFI [ME] control unit and drive train CAN to the fully integrated transmission control unit.

ESP® status:

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.

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 the chassis CAN 1, chassis gateway control unit and chassis FlexRay to the radar sensors control unit.

IMPORTANT The radar sensors control unit compares the actual acceleration with the requested acceleration. If the actual acceleration is not sufficient, then a higher torque is requested (e.g. situation on hill).

Braking torque:

The Electronic Stability Program control unit transmits information about the currently applied braking torque via chassis CAN 1, the chassis gateway control unit and chassis FlexRay to the radar sensors 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 sends corresponding values via the vehicle dynamics CAN, Electronic Stability Program control unit, chassis CAN 1, the chassis gateway control unit and chassis FlexRay to the radar sensors control unit.

IMPORTANT For reasons of safety and comfort the maximum (positive) acceleration of the automatic distance control is limited to approx. a = 3.5 m/s2 . It is dependent on the selected transmission mode and it responds anti-proportional 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 sends in control signals from the CC lever via the chassis CAN 1, the chassis gateway control unit and chassis FlexRay to the radar sensors control unit.

Driver overtake request (setting turn signal on combination switch):

The steering column tube module control unit directly reads in the switch position of the combination switch and sends them via the chassis CAN 1, the chassis gateway control unit and chassis FlexRay to the radar sensors control unit.

Vehicle speed/acceleration:

The vehicle speed is calculated on the basis of the wheel speeds. The acceleration is defined over the increase in rotational speed. The Electronic Stability Program control unit directly reads in the signals from the RPM sensors. The Electronic Stability Program control unit transmits appropriate information via the chassis CAN 1, chassis gateway control unit and chassis FlexRay to the radar sensors control unit:

GPS signals/signals for traffic assessment:

The NAV of the COMAND controller unit (for code (512) COMAND APS incl. DVD changer or code (527) COMAND APS with a single DVD drive (with navigation)) or the radio (for code (523) Radio MB Audio 20 or code (510) Audio 20 incl. CD changer) in combination with navigation module (for code (509) navigation box) adapted via the telematics CAN evaluates the global positioning system data while using additional information to the traffic evaluation and transmits appropriate information via the interior CAN, front SAM control unit, chassis CAN 1, chassis gateway control unit and chassis FlexRay to the radar sensors control unit.

IMPORTANT Information flows about topological events such as toll booths, roundabout traffic, curves radii, inclines or fells in the evaluation of the COMAND controller unit (for code (512) COMAND APS incl. DVD changer or code (527) COMAND APS with a single DVD drive (with navigation)) or the radio (for code (523) Radio MB Audio 20 or code (510) Audio 20 incl. CD changer) in order to allows an exact traffic evaluation.

Steering angle:

The steering angle is recorded by the steering angle sensor. The steering column tube module control unit directly reads in signals from the steering angle sensor and sends them via the chassis CAN 1, the chassis gateway control unit and chassis FlexRay to the radar sensors control unit.

Object recognition in the short range:

The DISTRONIC (DTR) sensors on the front bumper transmit appropriate signals via the radar CAN 1 to the radar sensors control unit.

Object recognition in the long range:

The front long range radar sensor registers objects in the long range area and sends the signals over the chassis FlexRay to the radar sensors 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 them via the chassis CAN 1, chassis gateway control unit and chassis FlexRay to the radar sensors control unit.

Brake pedal position:

Operation of the brake pedal is detected by the brake lights switch. The Electronic Stability Program control unit directly reads in the status of the brake light switch via the chassis CAN 1, chassis gateway control unit and chassis FlexRay to the radar sensors control unit.

The radar sensors control unit emits the following initial parameters (requests): 

Engage targeted gear (downshift or upshift):

The radar sensors control unit transmits the request "Engage targeted gear" via the chassis FlexRay, chassis gateway control unit and chassis CAN 1 to the Electronic Stability Program control unit: The Electronic Stability Program control unit evaluates this request as well as further driving dynamics requests internally and transmits them, according to their relevance, via the 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 request is however to be understood as a switching recommendation. Downshifting or upshifting of the A/T takes place autonomously itself by the fully integrated transmission control unit, dependent on the current operating condition.

Raise/reduce engine torque:

The radar sensors control unit transmits the request "Increase engine torque" or "Reduce engine torque" via the chassis FlexRay, chassis gateway control unit and chassis CAN 1 to the Electronic Stability Program control unit. The Electronic Stability Program control unit evaluates the request as well as further vehicle dynamic requests and sends them according to their relevance via the chassis CAN 1 to the CDI control unit or ME-SFI [ME] control unit. The CDI control unit or the ME-SFI [ME] control unit implements this request.

Raise/reduce braking torque:

The radar sensors control unit transmits the request "Increase braking torque" or "Reduce braking torque" via the chassis FlexRay, chassis gateway control unit and chassis CAN 1 to the Electronic Stability Program control unit. The Electronic Stability Program control unit reacts by directly controlling the traction system hydraulic unit, which reacts by increasing or decreasing the braking torque according to the brake torque.

Emit warning tones, system or warning messages

The radar sensors control unit sends the requests to output acoustic warnings, display system or warning messages request via the chassis FlexRay, the chassis gateway control unit and chassis CAN 2 to the instrument cluster.

Additional function requirements for DISTRONIC PLUS 

IMPORTANT If the SPEEDTRONIC LED (without code (494) USA version) lights up, the DISTRONIC PLUS is deactivated and the function variable SPEEDTRONIC (without Code (494) USA version) preselected.

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 following options are available for activating DISTRONIC PLUS:

Drive off from standstill without vehicle in detection range:

If there is not a stationary/moving vehicle in the detection range for the radar sensor system, the DISTRONIC PLUS function is active, but an automated drive-off does not take place. To initiate the drive-off procedure, the driver has to either briefly press the accelerator pedal or operate the Resume from memory switch on the CRUISE CONTROL lever to call up the last selected set speed (set speed ≥30 km/h (20 mph)).

Automated drive-off from standstill with vehicle in detection range:

If a stationary or moving vehicle is in the detection range of the radar sensor system, the vehicle follows, as long as the driver briefly operated the accelerator pedal beforehand or used the "Resume from memory" switch on the CC lever to call up the last selected set speed.

IMPORTANT For vehicles at a standstill a specified distance limit exists beyond which a stationary vehicle is no longer displayed.

Technical implementation 

To do this the radar sensors 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 (20 mph)) if a vehicle driving immediately ahead was detected. If the vehicle driving immediately ahead brakes or accelerates, the DISTRONIC PLUS can initiate the following measures for deceleration or acceleration of the vehicle:

The intervention by the brake system takes place by means of hydraulic pressure controlling in the wheel brake cylinder by the traction system hydraulic unit. To do this the Electronic Stability Program control unit assesses various variables such as the required braking torque.

The driver must press on the brake pedal if he sees that the instigated measures are not adequate to avoid a possible collision.

IMPORTANT If the driver does not intervene, an additional intervention by the brake system is made by the PRE-SAFE brake. Additional information on autonomous braking is available in the "PRE-SAFE brake" subfunction (with code (271) Autonomous intervention by the brake system/pedestrian protection and code (300) Reducing collisions (CMS)).

If the vehicle driving immediately ahead accelerates again, the engine torque is increased and the vehicle also accelerates. The increase in engine torque is dependent on the ascent or the descent involved, among other things.

The maximum (positive) acceleration is dependent on the selected transmission mode. The driver can influence the vehicle's acceleration behavior by selecting the transmission mode using the Transmission mode button.

The driver still has the option of operating the accelerator pedal to accelerate the vehicle (e.g. when overtaking). 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 and the "DISTRONIC passive" message goes off.

Technical implementation 

To do this the radar sensors control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

Change of driving lane (Overtake) 

For overtaking above a speed of v = 70 km/h (44 mph) the vehicle is also accelerated automatically. To this the driver must initiate the overtaking maneuver by setting the flasher. In as far as the automatic distance control is activated, the radar sensors 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.

When approaching a slowly moving vehicle and therefore an active automatic intervention by the brake system, this is then canceled insofar as the driver initiates the overtaking procedure by operating the turn signal. If required, the vehicle is additionally accelerated.

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 radar sensors control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

Convoy driving 

IMPORTANT The convoy driving function is only available in selected Western European countries with the appropriate legislation (overtaking on the right prohibited at speeds in excess of v = 80 km/h (v = 53 mph), as well as overtaking speed limit relative to the convoy of a max. v = 20 km/h (v = 12 mph)).

If the traffic situation at any given time results in the formation of a convoy on the left-hand side lane, which could theoretically be overtaken on the right lane, then this is detected by DISTRONIC PLUS.

A convoy overtaking maneuver on the right-hand lane (relative overtaking speed to convoy ≤20 km/h (12 mph), maximum overtaking speed v = 85 km/h (53 mph)) is only initiated when the following requirements are fulfilled:

Technical implementation 

Input factors:

Initial parameters:

Automatic speed control 

If the vehicle is in active distance control and the vehicle driving immediately ahead accelerates above v = 200 km/h (v = 120 mph) or removes itself from the detection area of the radar sensor system, the automatic distance control switches over into the automatic speed control.

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

Technical implementation 

To do this the radar sensors 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 tuns 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 sufficient, a visual and an acoustic warning is issued, and the driver has to press the brake pedal. If the driver fails to respond, PRE-SAFE brake initiates (in addition to the visual and acoustic warnings) an automated partial and then emergency braking.

IMPORTANT The negative acceleration (deceleration) is restricted to 50 % (approx. a = 5.0 m/s2 ) of the maximum brake power.

DISTRONIC PLUS is thereby deactivated. The driver is notified of this by emission of an intermittent tone over the warning buzzer and a warning indicator in the instrument cluster's multifunction display. The driver can subsequently reactivate the DISTRONIC PLUS.

Technical implementation 

To do this the radar sensors control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

Passing over roundabouts, T intersections and freeway exit lane 

Passing through rotaries, T intersections and freeway exits:

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, after this, no vehicle is detected driving immediately ahead, the vehicle accelerates or decelerates to the established set speed.

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

Technical implementation 

To do this the radar sensors 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. The deceleration here is due to the service brake. The service brake also secures a stationary vehicle against rolling away.

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

Technical implementation 

To do this the radar sensors control unit receives or transmits the following information or requests:

Input factors:

Initial parameters:

The following traffic situations show the limits of the DISTRONIC PLUS.

Fig 5: Overview Of DISTRONIC PLUS (Obstacles And Stationary Vehicles)
G07300324Courtesy of MERCEDES-BENZ USA

Obstacles and stationary vehicles

The DISTRONIC PLUS function does not brake for obstacles or stationary vehicles which were not previously detected as the target object.

If, for example, the detected vehicle turns off and there is an obstacle or stationary vehicles behind it, no automatic intervention by the brake system occurs.

Fig 6: Overview Of DISTRONIC PLUS (Curves, Curved Entrances And Exits)
G07300325Courtesy of MERCEDES-BENZ USA

Curves, curved entrances and exits:

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

Fig 7: Overview Of DISTRONIC PLUS (Vehicles Moving Across In Front Of One Own Vehicle)
G07300326Courtesy of MERCEDES-BENZ USA

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

The DISTRONIC PLUS function 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).

Fig 8: Overview Of DISTRONIC PLUS (Displaced Driving Style)
G10050075Courtesy of MERCEDES-BENZ USA

Displaced driving style:

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

Fig 9: Overview Of DISTRONIC PLUS (Lane Change By Other Vehicles)
G10050076Courtesy of MERCEDES-BENZ USA

Lane change by other vehicles:

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

Fig 10: Overview Of DISTRONIC PLUS (Narrow Vehicles)
G10050077Courtesy of MERCEDES-BENZ USA

Narrow vehicles:

The DISTRONIC PLUS function does not detect the vehicle in front at the edge of the road in time because it is (too) narrow. The distance to the vehicle in front becomes too small.

  Electrical function schematic for DISTRONIC PLUS   PE30.30-P-2053-97EAA 
  Overview of system components for driver assistance systems   GF54.00-P-9998CAM
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