Attention Assist, Function - GF54.30-P-0009LF

Model 217, 222 

up to model year 2018 

Courtesy of MERCEDES-BENZ USA

Function requirements, general 

• Engine running or drive train operational

The CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or "Drive train operational" signal over the drive train CAN, powertrain control unit and the suspension FlexRay to the Electronic Stability Program control unit.

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 in 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.

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 to the Electronic Stability Program control unit over the user interface CAN, electronic ignition lock control unit and suspension FlexRay.

The driver can select the following operating modes:

• "Standard"
• "Sensitive"
• "Off"

In "Sensitive" operating mode, the attention assistance system reacts more sensitively and issues warning messages sooner than in "Standard" operating mode.

In "Off" operating mode, the issuing of warnings is suppressed.

"Last-turned-on mode"

If one of the "Standard" or "Sensitive" operating modes was selected before an ignition cycle, this mode becomes active 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 the "Off" operating mode is selected, this is indicated by a crossed-out coffee cup symbol on the instrument cluster. If the attention assistance system is in one of the "Standard" or "Sensitive" operating modes, 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:

• "Attention Level" (bar graph, 5-stage)
• Driving time since last ignition cycle (in hours and minutes)
• Attention assistance system set to passive (e.g. vehicle speed v < 60 km/h or > 200 km/h)

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.

Courtesy of MERCEDES-BENZ USA

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.

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 has been exceeded (only one red bar is displayed), the Electronic Stability Program control unit sends the request to output a warning message via suspension FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster and COMAND controller unit, which evaluate it. The warning message "Attention Assist: Break!" then appears on the instrument cluster, and the driving time since the last break is displayed. A warning tone is also issued over the instrument cluster speaker. The instrument cluster directly actuates the instrument cluster speaker. The Electronic Stability Program control unit transmits the request to output a warning tone via suspension FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster.

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 via the steering LIN, the steering column tube module control unit, the suspension FlexRay, the electronic ignition lock control unit and the user interface CAN to the instrument cluster. In addition, the steering column tube module control unit transmits these via suspension FlexRay to the Electronic Stability Program control unit.

A repeated warning message can be issued at the earliest after expiry of t = 15 min.

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 output a warning message via the suspension FlexRay, electronic ignition lock control unit and user interface CAN to the COMAND controller unit. The COMAND controller unit uses the GPS signals and the navigation data to determine suitable rest facilities. The COMAND controller unit actuates the Audio/COMAND display via telematics CAN and transmits the corresponding video signals via the LVDS line.

Warning message in the instrument cluster 

Courtesy of MERCEDES-BENZ USA

Essentially, the following information is evaluated:

• Time of day
• Driving time
• Steering movements
• Vehicle speed
• Vehicle longitudinal/lateral acceleration and yaw rate
• Control interventions

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 user interface CAN, electronic ignition lock control unit and suspension FlexRay. The received time is checked for plausibility by means of evaluating the ambient brightness. The ambient light intensity is recorded by the light sensor. The rain/light sensor with additional functions directly reads in the signals of the light sensor and sends information about the ambient brightness (twilight stage) to the Electronic Stability Program control unit via the rain/light sensor LIN, front SAM control unit, interior CAN, electronic ignition lock control unit and suspension FlexRay.

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 steering wheel angle sensor signals directly and sends information on steering wheel angle and steering wheel velocity to the Electronic Stability Program control unit via suspension FlexRay.

Vehicle speed:

The Electronic Stability Program control unit calculates the vehicle speed from the wheel speeds.

Vehicle longitudinal/lateral acceleration and yaw rate:

Information about the vehicle's longitudinal and lateral acceleration and the yaw rate is acquired by the turn rate, lateral acceleration and longitudinal acceleration sensor. The yaw rate sensor for lateral and longitudinal acceleration sends the information on vehicle longitudinal/lateral acceleration and yaw rate to the Electronic Stability Program control unit over the vehicle dynamics CAN.

Control interventions:

The following control interventions will disable the detection of steering patterns:

• Operation of the COMAND controller unit (the first operation is faded out, continuous operation is evaluated as distraction)
• Steering column adjustment switch (without CODE 443 (Steering wheel heater)) or steering column adjustment and steering wheel heater switch (with CODE 443 (Steering wheel heater))
• Combination switch
• Cruise control lever
• Left multifunction steering wheel button group or right multifunction steering wheel button group

The COMAND controller unit sends information on audio system control interventions to the Electronic Stability Program control unit via user interface CAN, electronic ignition lock control unit and suspension FlexRay.

The steering column tube module control unit sends information on control interventions at the steering column adjustment switch (without code (443) Steering wheel heater) or steering column adjustment switch and steering wheel heater (with code (443) Steering wheel heater), at the combination switch, CC lever and at the multifunction steering wheel button groups to the Electronic Stability Program control unit over the suspension FlexRay.

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.

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

• Driving time of t < 30 min
• Poor road surface condition (e.g. surface undulations, pot holes)
• Strong crosswind
• Sporty driving style (e.g. high cornering speeds, high acceleration)
• Vehicle speed mainly v < 60 km/h or v > 200 km/h
• Activated Steer Assist (with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot))
• Incorrectly set time
• Active driving situations (e.g. lane change, change of speed)

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

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

   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, e.g. 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 driver types are particularly challenging for the attention assistance system, e.g. drivers with extremely smooth or extremely active steering behavior.

4. Influence of the time on the sensitivity of the attention assistance system:

   The attention assistance system function reacts differently depending on the time in accordance with the human bio-rhythm (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 assistance system:

   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 due to distraction or mild fatigue:

   The attention assistance system 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 behavior due to other factors:

   Besides fatigue or increasing inattentiveness other factors can also significantly change the steering ability, and influence the objective assessment variables as determined by the attention assistance system, 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 the 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-2054-97SEA
	Overview of system components for driver assistance systems		GF54.00-P-9998LF