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

MODEL 204.0/2 with CODE (442) Comfort multifunction steering wheel as of model year 2012/YoM 11 model refinement package 

MODEL 204.3 with CODE (442) Steering wheel heater 

MODEL 204.9 with CODE (442) Comfort multifunction steering wheel as of model year 2013/facelift 12 

Function requirements, general 

• Circuit 15 ON

The electronic ignition lock control unit sends the status of circuit 15 via the chassis CAN to the Electronic Stability Program control unit.

Attention Assist, general 

The attention assistance system function is integrated into 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 = 80 to 180 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 assistance system 

The attention assistance system function can be activated or deactivated in the "Assist." menu in the "Attention Asst." menu level on the instrument cluster.

The status of the attention assistance system function is sent by the instrument cluster over the chassis CAN to the Electronic Stability Program control unit.

If the function is active a coffee cup symbol is shown in the instrument cluster's multifunction display.

The driver handling characteristics are also analyzed when the function is switched off. When the function is switched on the handling characteristics can be considered right from the start.

Attention assistance system function activated, shown on instrument cluster up to 31.5.11 

If the Attention Assist function is active a coffee cup symbol is shown in the instrument cluster's multifunction display.

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.

If the warning threshold has been exceeded, the Electronic Stability Program control unit sends a request to issue a warning message over the chassis CAN on the instrument cluster.

The instrument cluster's multifunction display then shows the "Attention Assist: Break!" warning.

The warning buzzer integrated in the instrument cluster additionally issues a double four-tone signal.

The warning message can be acknowledged using the OK button in the left multifunction steering wheel button group.

The steering wheel electronics directly reads in the signals of the OK button and sends them over the steering LIN, steering column tube module control unit and chassis CAN to the Electronic Stability Program control unit.

A repeated warning message can only be issued following expiry of

t = 15 minutes.

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 the current time over the chassis CAN to the Electronic Stability Program control unit.

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 rain/light sensor data over the wiper/inside rearview mirror LIN and sends the data over the chassis CAN to the Electronic Stability Program control unit.

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.

Vehicle longitudinal/lateral acceleration and yaw rate:

Information on the vehicle longitudinal and lateral acceleration as well as the yaw rate are evaluated by the Electronic Stability Program control unit.

The yaw behavior of the vehicle is detected by the yaw rate sensor for lateral and longitudinal acceleration. This is designed as a separate component on vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist and model 204.077/277/377 and it communicates over the dynamics CAN with the Electronic Stability Program control unit. For vehicles, for which the above-mentioned limitation does not apply, the yaw rate sensor for lateral and longitudinal acceleration is integrated into the Electronic Stability Program control unit.

Steering movements:

Steering movements are recorded by the steering angle sensor. The steering column tube module control unit directly reads in the signals of the steering angle sensor and sends them over the chassis CAN to the Electronic Stability Program control unit.

Vehicle speed:

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

The wheel speeds are recorded by rpm sensors and their signals are read in directly by the Electronic Stability Program control unit:

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

• Radio or COMAND controller unit
• Combination switch
• Cruise control lever
• Steering column adjustment switch
• Left multifunction steering wheel button group or right multifunction steering wheel button group

The control interventions on the control buttons of the radio or the COMAND controller unit are sent by the radio or the COMAND controller unit over the interior CAN, front SAM control unit and the chassis CAN to the Electronic Stability Program control unit.

Control interventions at the steering column adjuster switch, the combination switch, the cruise control lever and the multifunction steering wheel button groups are read in by the steering column tube module control unit and sent over the chassis CAN to the Electronic Stability Program control unit.

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 following operating conditions are deemed to be irrelevant:

• Poor road surface condition

  (e.g. surface undulations, pot holes)

• Strong crosswind
• Sporty driving style

  (e.g. high cornering speeds, high acceleration)

• Vehicle speed range predominantly below

  v = 80 km/h or above v = 180 km/h

• Operation of audio system incl. telephony
• Active driving situation

  (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 too short in active vehicle speed range:

   The attention assistance system function analyzes the development of driving behavior over time. At the start of the journey the individual handling characteristic is classified. If the handling characteristic changes permanently a warning is issued. If the driving time in the active range (speed between 80 and 180 km/h) is too short, a warning is not issued.

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

   In an active vehicle speed range

   (v = 80 to 180 km/h) the handling characteristics cannot be evaluated, when certain factors occur, e.g. frequent lane changing, twisty roads, frequent control interventions, surface undulations, crosswinds or a dynamic driving style. If these factors occur permanently the driving time in the active range is too short (see also Point  1).

3. Individual factors of driving situation or handling characteristics: The attention assistance system function determines a change in driving behavior. This change must not always be down to fatigue or increasing inattentiveness, it can also be the result of the steering ability characteristics. Certain driver types present specific challenges to the system, e.g. driver with extremely smooth or extremely active steering ability.
4. Influence of time on sensitivity of function:

   The attention assistance function responds in accordance with the human biorhythm depending on the time (e.g. including the afternoon slump). This biorhythm was determined representatively, it can differ for individuals however.

5. Influence of driving time on sensitivity of function:

   As the length of driving time without a break increases, the sensitivity of the attention assistance system 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:

   The Attention Assist function 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 level of fatigue sensitivity and the assessment values determined by the attention assistance system function may differ.

7. Change in steering ability through other factors:

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

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