Active Distance Assist Distronic, Function - GF30.30-S-3315TRF
Model 447
With Code ET4 (Active Distance Assist DISTRONIC)
With Code XM0 (Facelift)
Illustration shows MODEL 447.8
Shown On Model 447.6/7
Function requirements, general
- No undervoltage or overvoltage
- DISTRONIC programmed in the electronic ignition lock control unit (EZS) (N73).
- Active Distance Assist DISTRONIC electric controller unit (B92/1) correctly calibrated and coded
- DISTRONIC switched on via the cruise control lever (S40/4)
- Radar sensor system soiling and function test for the radar sensor system completed successfully
- Electronic Stability Program (ESP®) not switched to passive mode
- No active ESP® intervention recognized
- Vehicle not moving in a reverse direction or skidding
- Drive range "D" engaged (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
- Parking brake not operated
- Standstill control, enable issued (driver's door/driver belt buckle, and front passenger door closed).
DISTRONIC in general
The units and values for the speed shown in the following should be assigned to the possible national versions. The details in mph ("miles per hour") refer to vehicles with a miles indicator.
DISTRONIC (code ET4 (Active Distance Assist DISTRONIC)) automatically regulates the speed and the distance to the vehicle in front according to the specification of the driver in a vehicle speed range from 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).
The control is realized by the Active Distance Assist DISTRONIC electric controller unit (B92/1). The electric controller unit for the Active Distance Assist DISTRONIC intervenes in the engine management and the braking system for implementation of DISTRONIC active.
There is a distance warning function in DISTRONIC that warns the driver, visually and acoustically, when the distance to the vehicle in front is too low as well as of possible collisions with vehicles or stationary obstacles in its lane. If the driver reacts to the warning tone and brakes, they will be supported in this by Active Brake Assist (with code BA3 (Active Brake Assist)).
This calculates the required brake force amplification according to the situation. A possible collision can be prevented or at least its consequences can be mitigated.
The visual warnings and warning tones are output via the instrument cluster (IC) control unit (A1/1):
- Visual warnings: system or warning messages via the multifunction display (A1/1p13) or. DISTRONIC warning lamp (A1/1e43)
- Warning tones: instrument cluster speaker (H4/61)
The individual DISTRONIC functions are activated/deactivated and operated via the cruise control lever (S40/4).
The menu settings in the instrument cluster (IC) control unit the distance graphic can be switched on and switched off.
The Active Distance Assist DISTRONIC electric controller unit is connected to the on-board electronics via chassis CAN (CAN E).
The following subfunctions in the DISTRONIC are described in the separate partial function "Cruise control (CC) Function" description:
- Automatic speed control
- Variable SPEEDTRONIC
- Permanent limiter
DISTRONIC requires the following input factors to implement the distance control and distance warning functions:
- Object recognition in the range from 0.2 to 200 m
The integral radar sensor performs a soiling and function test to secure its perfect function after every engine start. The function test requires an object to be located in the detection area the radar sensor, that is used as a reference value for the function test.
If a malfunction is detected or no objects (for the function test) are present in the detection range, the DISTRONIC cannot be activated.
Operation
DISTRONIC is operated via the cruise control lever (S40/4). The steering column tube module (MRM) control unit (N80) directly reads in the control signals from the cruise control lever and transmits these to the Active Distance Assist DISTRONIC electric controller unit via chassis CAN.
Design of the cruise control lever
Operation via the cruise control lever
Input factors
The Active Distance Assist DISTRONIC electric controller unit evaluates the following input factors:
- Operating condition of engine/drivetrain (function requirements)
- The CDI control unit or the ME-SFI [ME] control unit transmits the "Engine running" or "Drivetrain operational" signal via drivetrain CAN (CAN C), powertrain control unit (N127) and chassis CAN to the Active Distance Assist DISTRONIC electric controller unit.
- Status of parking brake (function requirements)
- The Electronic Stability Program (ESP) control unit (N30/4) transmits the status of the parking brake via chassis CAN to the Active Distance Assist DISTRONIC electric controller unit.
- Engaged drive range (function requirement)/drive program (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC)):
- The fully integrated transmission control (VGS) electric controller unit transmits information on the engaged drive range and the drive program to the Active Distance Assist DISTRONIC electric controller unit.
- Model 447.8:
The central operating unit (COU) [ZBE] control unit (A40) reads in the status of the AGILITY SELECT switch (A40/1s1) via LCP-LIN (LIN A3) from the left lower control panel control unit (LCPL [UBFL]) (A40/1) and transmits it to the fully integrated transmission control (VGS) electric controller unit.
- ESP® status:
- The Electronic Stability Program (ESP) control unit transmits the status of the ESP® to the Active Distance Assist DISTRONIC electric controller unit.
- Engine drive torque:
- Information concerning the currently available engine drive torque is transmitted by the CDI control unit or ME-SFI [ME] control unit to the Electronic Stability Program (ESP) control unit, which evaluates this accordingly and transmits it to the Active Distance Assist DISTRONIC electric controller unit.
- Braking torque:
- Information on the currently applied braking torque is transmitted by the Electronic Stability Program (ESP) control unit to the Active Distance Assist DISTRONIC electric controller unit.
- Acceleration/yaw rate:
- The acceleration/yaw rate is detected by the integral turn rate, yaw and longitudinal acceleration sensor in the Electronic Stability Program (ESP) control unit. The Electronic Stability Program (ESP) control unit transmits corresponding values to the Active Distance Assist DISTRONIC electric controller unit.
The Active Distance Assist DISTRONIC electric controller 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).
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. With increasing vehicle speed smaller accelerations are permitted.
- Driver request via the cruise control lever:
- The driver requests made over the CC lever are read in directly by the steering column tube module (MRM) control unit. The steering column tube module (MRM) control unit transmits operation signals from the cruise control lever to the Active Distance Assist DISTRONIC electric controller unit.
- Driver request to overtake (sets the turn signal lights on the combination switch):
- The steering column tube module (MRM) control unit reads in the switch position of the combination switch (S4) directly and transmits it to the Active Distance Assist DISTRONIC electric controller 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 (ESP) control unit transmits the wheel speed signals and the vehicle speed to the Active Distance Assist DISTRONIC electric controller unit.
- Steering wheel angle:
- The steering angle is recorded by the steering wheel angle sensor. The steering column tube module (MRM) control unit reads in the signals from the steering wheel angle sensor directly and transmits them to the Active Distance Assist DISTRONIC electric controller unit.
- Object recognition in the range of the radar sensor
- The radar sensor integrated in the Active Distance Assist DISTRONIC electric controller unit detects objects in the range from 0.2 to 200 m. The Active Distance Assist DISTRONIC electric controller unit evaluates these signals directly.
- Accelerator pedal position:
- Operation of the accelerator pedal is detected by the accelerator pedal module (B37/4).
The powertrain control unit reads in the signals from the accelerator pedal module directly and transmits them to the Active Distance Assist DISTRONIC electric controller unit.
- Brake pedal position:
- Operation of the brake pedal is detected by the brake light switch (S9/3). The Electronic Stability Program (ESP) control unit reads in the status of the brake light switch directly and transmits it to the Active Distance Assist DISTRONIC electric controller unit.
Output factors
The Active Distance Assist DISTRONIC electric controller unit issues the following initial parameters (requests):
- Engage requested gear (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC)) (shift up or down):
- The Active Distance Assist DISTRONIC electric controller unit transmits the "Engage requested gear" request to the Electronic Stability Program (ESP) control unit.
The Electronic Stability Program (ESP) control unit evaluates this request as well as further driving dynamics requests and transmits them, according to their relevance, to the fully integrated transmission control (VGS) electric controller unit. This request is to be understood as a gearshift recommendation.
Downshifting or upshifting of the A/T takes place autonomously by the integrated transmission control electric controller unit (VGS, dependent on the current operating condition.
- Increase/reduce engine torque:
- The Active Distance Assist DISTRONIC electric controller unit transmits the "Increase engine torque" or "Reduce engine torque" request to the Electronic Stability Program (ESP) control unit.
The Electronic Stability Program (ESP) control unit evaluates this request as well as further driving dynamics requests and transmits them, according to their relevance, to the CDI control unit or the ME-SFI [ME] control unit. The CDI control unit or the ME-SFI [ME] control unit implements this request accordingly.
- Increase/reduce braking torque:
- The Active Distance Assist DISTRONIC electric controller unit transmits the "Increase braking torque" or "Reduce braking torque" request to the Electronic Stability Program (ESP) control unit.
The Electronic Stability Program (ESP) control unit reacts by directly actuating the traction system hydraulic unit (1), which increases or reduces the braking torque according to the actuation.
- Issue warning tones and system or warning messages:
- The Active Distance Assist DISTRONIC electric controller unit transmits the requests to output warning tones and system or warning messages to the instrument cluster (IC) control unit (A1/1), which issues the corresponding system or warning messages via the multifunction display (A1/1p13) or the DISTRONIC warning lamp (A1/1e43) and directly actuates the instrument cluster speaker (H4/61).
Additional function requirements for DISTRONIC
Cruise control lever in position: the SPEEDTRONIC LED (11) does not light up.
If the SPEEDTRONIC LED on the cruise control lever lights up, DISTRONIC is deactivated and the variable SPEEDTRONIC function is programmed.
DISTRONIC function sequence
The description of the DISTRONIC function takes place, as an example, in the following chronological sequence:
- Automatic distance control
- Automatic speed control
- Going back into a lane/person in the front regulation
- Automated Stop Vehicle
The sequence can vary depending on the driver requests and the current traffic situation.
Automatic distance control
Automatic distance control can be activated while driving (v < 30 km/h (20 mph)) only if a vehicle in front has been detected. If the vehicle traveling in front brakes or accelerates, DISTRONIC can initiate the following measures for vehicle deceleration or vehicle acceleration:
- Increase/reduce engine torque.
- Increase/reduce braking torque.
The brake application takes place by means of hydraulic pressure controlling in the wheel brake cylinder by the traction system hydraulic unit according to the current vehicle status. To do this, the Electronic Stability Program (ESP) control unit assesses a number of variables such as the required braking torque.
The driver must press on the brake pedal is 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 increase in engine torque is dependent on the ascent or the descent involved, among other things.
The maximum (positive) acceleration depends on the selected drive program (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC)).
Model 447.8:
The driver can influence the acceleration behavior of the vehicle through selection of the transmission mode over the AGILITY SELECT switch.
The driver still has the possibility to accelerate the vehicle (e.g. when overtaking) by pressing the accelerator pedal. The automatic acceleration is put out of action for as long as the driver uses the accelerator pedal. The multifunction display shows the "DISTRONIC passive" message. 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.
The Active Distance Assist DISTRONIC electric controller unit receives or transmits the following information or requests for this:
Input factors:
- Engine drive torque
- Acceleration/yaw rate
- Driver request via the cruise control lever
- Vehicle speed/acceleration
- Object recognition in the range of the radar sensor
- Accelerator pedal position
Initial parameters:
- Increase/reduce engine torque.
- Engage requested gear (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
- Increase/reduce braking torque.
- Output warning tones, system messages or warnings.
Automatic speed control
If the vehicle is in an active distance control and the vehicle in front accelerates to over v = 200 km/h (120 mph) or leaves the radar sensor system detection range, the automatic distance control automatically switches to automatic speed control.
Automatic speed control is described in detail in the separate "Cruise control (CC) Function" subfunction.
The Active Distance Assist DISTRONIC electric controller unit receives or transmits the following information or requests for this:
Input factors:
- Engine drive torque
- Acceleration/yaw rate
- Vehicle speed/acceleration
- Driver request via the cruise control lever
- Accelerator pedal position
- Brake pedal position
Initial parameters:
- Increase/reduce engine torque.
- Engage requested gear (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
- Increase/reduce braking torque.
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 vehicle moving into the lane is below the preselected value, DISTRONIC brakes the vehicle. If the requested braking power is not sufficient, a visual warning and a warning tone are output and the driver has to depress the brake pedal.
DISTRONIC is thereby deactivated. The driver is notified of this by the output of an intermittent warning tone through the instrument cluster speaker and a warning display on the instrument cluster's multifunction display. The driver can subsequently reactivate the DISTRONIC.
The negative acceleration (deceleration) is limited to approx. a = 4.0 m/s2
of the maximum possible braking power.
The Active Distance Assist DISTRONIC electric controller unit receives or transmits the following information or requests for this:
Input factors:
- Vehicle speed
- Steering angle
- Object recognition in the range of the radar sensor
- Brake pedal position
Initial parameters:
- Increase/reduce engine torque.
- Engage requested gear (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
- Increase/reduce braking torque.
- Output warning tones, system messages or warnings.
Automated Stop Vehicle
In an active DISTRONIC, the vehicle will follow the vehicle driving in front to a standstill. The deceleration here is due to the service brake. The service brake also secures a stationary vehicle against rolling away.
After a defined time period the electric parking brake is also activated (standstill control safety strategy).
Securing the vehicle using DISTRONIC is no substitute for securing the vehicle during parking.
The Active Distance Assist DISTRONIC electric controller unit receives or transmits the following information or requests for this:
Input factors:
- Vehicle speed
- Object recognition in the range of the radar sensor
Initial parameters:
- Increase/reduce engine torque.
- Engage requested gear (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
- Increase/reduce braking torque.
The following traffic situations show the limits of the DISTRONIC:
Obstacles and stationary vehicles
The DISTRONIC 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 stationary vehicles behind it, no automatic intervention by the brake system occurs.
Curves, curved entrances and exits
The DISTRONIC can only provides limited detection of vehicles in curves. One's own vehicle can then brake unexpectedly or late.
Vehicles moving across in front of one's own vehicle
DISTRONIC 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).
Offset driving style
The DISTRONIC may not be able to detect vehicles driving displaced to one side. The distance to the vehicle in front becomes too small.
Lane change by other vehicles
The DISTRONIC does not yet detect the vehicle moving into the lane. The distance to the vehicle moving into the lane becomes too small.
Narrow vehicles
DISTRONIC PLUS does not detect the vehicle in front at the edge of the carriageway because of its narrow width. The distance to the vehicle in front becomes too small.
| Overview of system components for driver assistance systems | GF54.00-S-9998TRF |