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Attention assist, function - GF54.30-P-0009FQM

MODEL 218 as of model year 2015 

Fig 1: Attention Assist - Block Diagram
G10083150Courtesy of MERCEDES-BENZ USA

Function requirements, general 

IMPORTANT The CDI control unit or ME-SFI [ME] control unit sends the signal "Engine running" or "Drivetrain operational" to the Electronic Stability Program control unit via chassis CAN 1.

Attention Assist, general 

Attention Assistance is located in the Electronic Stability Program control unit. By evaluating steering patterns any onset of driver fatigue (e.g. on long monotonous journeys on freeways and highways) can be detected. The steering patterns are evaluated within a vehicle speed range of v = 60 to 200 km/h. If any appropriate signs indicating fatigue or increasing lack of attention by the driver are recognized, the driver is prompted to take a break by means of visual and acoustic warnings.

IMPORTANT Development of this software is based on experience gathered with test persons, whose different handling characteristics at night and day times were evaluated.

Function sequence for Attention Assist 

The Attention Assist can be activated or deactivated in the "Assist." menu in the "Attention Asst." menu level on the instrument cluster. The instrument cluster sends the status of the attention assistance system via chassis CAN 2, the front SAM control unit and chassis CAN 1 to the Electronic Stability Program control unit.

The driver can select the following operating modes:

In "Sensitive" operating mode, the Attention Assist reacts more sensitively and issues warning messages sooner than in "Standard" operating mode.

The output of warnings is suppressed in "Off" operating mode.

IMPORTANT "Last-turned-on mode":

If "Standard" or "Sensitive" operating mode was selected before an ignition cycle, this mode is activated again after the next ignition cycle. If the attention assistance system is switched off while driving (operating mode "Off"), the operating mode that was selected before switching off is automatically active after the next ignition cycle. If "Off" operating mode has been selected, this is indicated by a crossed-out coffee cup symbol on the instrument cluster. If the attention assistance system is in "Standard" or "Sensitive" operating mode, the coffee cup symbol is not displayed.

The driver can call up the following additional information via the "Info page" in the "Attention Asst." menu level of the instrument cluster:

IMPORTANT If the attention assistance system is switched to passive, the "System passive" message is output on the instrument cluster as well as the driving time since the start of driving and the bar graph.

IMPORTANT The driver handling characteristics are also analyzed when the attention assistance system is switched to passive. If the attention assistance system is activated when driving, the entire journey from the start is taken into consideration.

At the start of the journey the Electronic Stability Program control unit uses an algorithm to determine the driver's individual warning threshold. This is the driving time and the time of day. 5 bars (green, yellow, red) are shown in the "Attention Level" display. The Electronic Stability Program control unit sends the request to display the corresponding information over the chassis FlexRay, electronic ignition lock control unit and the user interface CAN to the instrument cluster.

If the number of indicators for lack of attention or fatigue goes up or in the event of a longer driving distance, the number of bars goes down.

If the warning threshold is exceeded (only one red bar is displayed), the Electronic Stability Program control unit sends a request via chassis CAN 1, the front SAM control unit and chassis CAN 2 to the instrument cluster to issue a warning and a warning tone.

The warning message "Attention Assist: Pause!" and the driving time since the last break are shown on the multifunction display. An acoustic warning is also issued via the warning buzzer. The instrument cluster actuates the warning buzzer directly.

The warning message can be acknowledged using the OK button in the left multifunction steering wheel button group. The steering wheel electronics read in the signals of the O. K. button directly and transmit this to the instrument cluster via the steering LIN, the steering column tube module control unit, chassis CAN 1, front SAM control unit and chassis CAN 2. The steering column tube module control unit also transmits the status of the OK button via chassis CAN 1 to the Electronic Stability Program control unit.

IMPORTANT A renewed warning message is issued at the earliest after expiry of t = 15 minutes.

Vehicles with code (522) Audio 20 radio or code (531) COMAND APS:

If the warning threshold is exceeded, as well as the warning message the nearest rest facilities are displayed to the driver in the Audio/COMAND display. Only premium parking places with a gas station and hospitality are taken into consideration. The display of suitable stops can be deactivated using the "Messages" menu on the Audio/COMAND display. The system remains deactivated after the next ignition cycle.

The Electronic Stability Program control unit sends the request to issue a warning message via chassis CAN 1, the front SAM control unit and interior CAN to the radio or to the COMAND control unit. The radio or the COMAND controller unit uses the GPS signals and the data from the navigation system to determine suitable rest facilities. The radio or the COMAND controller unit actuates the Audio/COMAND display via the telematics CAN and transmits the corresponding video signals via the LVDS line.

Essentially, the following influencing factors are evaluated:

Time of day:

The time of day is also defined by the current time. The instrument cluster sends this to the Electronic Stability Program control unit via chassis CAN 2, front SAM control unit and chassis CAN 1. The received time is checked for plausibility by means of evaluating the ambient brightness. The ambient brightness is sensed by the rain/light sensor. The front SAM control unit reads in the data from rain/light sensor via the wiper/inside rearview mirror LIN, evaluates this data and sends the corresponding signal to the Electronic Stability Program control unit via chassis CAN 1.

IMPORTANT If there is a transition between dusk and dawn at an implausible time, an entry is made in the Electronic Stability Program control unit diagnostic memory

Driving time:

The driving time is determined by the Electronic Stability Program control unit.

Steering movements:

Steering movements are recorded by the steering wheel angle sensor.

The steering column tube module control unit reads in the signals of the steering wheel angle sensor directly and transmits information about the steering wheel angle and the steering wheel velocity to the Electronic Stability Program control unit via chassis CAN 1.

Vehicle speed:

The vehicle speed is calculated by the Electronic Stability Program control unit using the wheel speed.

Vehicle longitudinal/lateral acceleration and yaw rate:

Information about the vehicle's longitudinal and lateral acceleration and the yaw rate is recorded 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.

Control interventions:

Control interventions at one of the following components disable the detection of steering patterns:

The radio (with code (505) 20 NTG5 radio without navigation capability or code (522) Audio 20 radio) or the COMAND controller unit (with code (531) COMAND APS) sends information about control interventions at the audio system via the interior CAN, front SAM control unit and chassis CAN 1 to the Electronic Stability Program control unit.

The steering column tube module control unit sends information about control interventions at the cruise control lever, the steering column adjustment switch (without code (443) Steering wheel heater) or the steering column adjustment and steering wheel heater switch (with code (443) Steering wheel heater), the combination switch and the multifunction steering wheel button groups to the Electronic Stability Program control unit via chassis CAN 1.

IMPORTANT The steering wheel electronics read in the control interventions on the multifunction steering wheel button groups directly and transmit them to the steering column tube module control unit over the steering LIN.

Hands-off detection:

The electrical power steering control unit sends the hands-off detection status via chassis CAN 2, the front SAM control unit and chassis CAN 1 to the Electronic Stability Program control unit or the regenerative braking system control unit. The Electronic Stability Program control unit uses this information to determine whether and at which time intervals the driver is making steering movements.

The Attention Assist only operates restrictedly under the following circumstances, and any warnings that are output are delayed:

Also valid is the following function information which can lead to possible function complaints:

  1. No warning issued because driving time too short in active vehicle speed range:

    The Attention Assist analyzes the chronological development for the handling characteristics. At the start of the journey the individual handling characteristic is classified. If the handling characteristic changes permanently a warning is issued. If the travel time in the active range is too short, no warning is issued.

  2. No warning because of restrictions associated with the system limits:

    The handling characteristics cannot be evaluated in the active vehicle speed range if certain factors occur such as frequent lane changing, twisty roads, frequent control interventions, surface undulations, crosswinds or a dynamic driving style.

  3. Personal driving behavior:

    The attention assistance system detects changes in driving behavior. These changes cannot always be explained as fatigue or increasing inattentiveness, rather they can also be caused by peculiarities in steering behavior. Certain types of driver present particular challenges for attention assistance systems, e.g. drivers with extremely smooth or extremely active steering behavior.

  4. Influence of the time on the sensitivity of the Attention Assist:

    The attention assistance system function reacts differently depending on the time in accordance with the human biorhythm (e.g. the mid-day low). These results are determined representatively, but they may also differ on an individual basis.

  5. Influence of driving time on the sensitivity of the Attention Assist:

    As the length of driving time without a break increases, the sensitivity of the Attention Assist function also increases. The weighting of the driving time is based on surveys and correspond to the average fatigue characteristics.

  6. Warning because of distraction or mild fatigue:

    Attention Assist can not only warn in the event of fatigue, it can also warn when a change in handling characteristics occurs, e.g. where the driver is greatly distracted. Therefore, a warning issued because of increasing inattentiveness is also to be deemed correct. The subjective fatigue sensitivity and the objective assessment variable determined by the Attention Assist are different.

  7. Change in steering ability through other factors:

    Next to fatigue or increasing inattentiveness other factors can also significantly change the steering ability, and influence the objective assessment variables as determined by the Attention Assist, e.g. increasingly slippery road surface, worsening visibility, narrowing roadway, worsening roadway.

  8. Influence of Steer Assist (with code (266) DISTRONIC PLUS with Steer Assist and Stop & Go Pilot) on steering pattern evaluation:

    If the steering assistance system is active, it is unclear whether steering movements have been made by the driver or by the Steer Assist.

Attention Assist electrical function schematic PE54.71-P-2054-97XAB
Overview of system components for driver assistance systems GF54.00-P-9998FQM 
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