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

MODEL 207 up to model year 2014 

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 (without code (233) DISTRONIC PLUS) or to the Premium Electronic Stability Program control unit (with code (233) DISTRONIC PLUS).

Attention Assist, general 

The attention assistance system is implemented by 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 corresponding steering patterns are detected, 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 of the instrument cluster. The status of the attention assistance system is sent by the instrument cluster over the chassis CAN to the Electronic Stability Program control unit. When the attention assistance system is active, a coffee cup icon appears in the multifunction display of the instrument cluster.

The driver handling characteristics are also analyzed when the Attention Assist is switched off. When the function is switched on, the handling characteristics can therefore be taken into consideration right from the start.

Attention Assist activated, shown on instrument cluster up to 31.5.11 

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 is exceeded, the Electronic Stability Program control unit sends the request to issue a warning message to the instrument cluster via the chassis CAN. The multifunction display of the instrument cluster then shows the "Attention Assist: Break!" warning message. 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 read in the signals from the left multifunction steering wheel button group directly and transmits these to the Electronic Stability Program control unit via steering LIN, steering column tube module control unit and chassis CAN.

A repeated warning message can only be issued following expiry of t = 15 minutes.

The following influencing factors are evaluated to implement the function:

• 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 transmits the current time to the Electronic Stability Program control unit via chassis CAN. 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 with fuse and relay module reads in the data from the rain/light sensor via the wiper/inside rearview mirror LIN and sends this data via 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.

Steering movements:

Steering movements are recorded by the steering angle sensor. The steering column tube module control unit reads in the signals from the steering angle sensor directly and sends them via 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 the following sensors:

• Left front axle RPM sensor
• Right front axle RPM sensor
• Left rear axle RPM sensor
• Right rear axle RPM sensor

The Electronic Stability Program control unit directly reads in the signals from the RPM sensors.

Vehicle longitudinal/lateral acceleration and yaw rate:

Information about the vehicle longitudinal and lateral acceleration as well as the yaw rate is 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 which communicates with the Electronic Stability Program control unit via the vehicle dynamics CAN.

Control interventions:

The following controls in the immediate vicinity of the driver are monitored:

• Radio (with code (523) MB Audio 20 radio or code (510) Audio 20 with CD changer) or radio with auto pilot system (with code (525) MB Audio 50 APS radio or code (511) Audio 50 APS incl. DVD changer) or COMAND controller unit (with code (512) COMAND APS incl. DVD changer or code (526) COMAND with single DVD drive (without navigation) or code (527) COMAND APS with single DVD drive (with navigation) or code (528) COMAND incl. DVD changer)
• Combination switch
• Cruise control lever
• Steering column adjustment switch (with code (275) Memory package (driver seat, steering column, mirror))
• Left multifunction steering wheel button group or right multifunction steering wheel button group

The radio or the COMAND controller unit sends information about audio system control interventions to the Electronic Stability Program control unit via the interior CAN, front SAM control unit and chassis CAN.

The steering column tube module control unit sends information about control interventions at the steering column adjustment switch, the combination switch, the cruise control lever and the multifunction steering wheel button groups to the Electronic Stability Program control unit via the chassis CAN.

The steering wheel electronics read in the signals from the multifunction steering wheel button groups directly and transmits them to the steering column tube module control unit via steering LIN.

A warning is suppressed under the following conditions as no inferences about the attentiveness of the driver can be drawn from the driving behavior:

• 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
• 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 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 driving time in the active range (speed between 80 and 180 km/h) is too short, a warning is not issued.

2. No warning in the case of external influences which affect driving behavior:

   Driving behavior is not evaluated when no inferences about the attentiveness of the driver can be drawn (e.g. frequent lane change, twisty roads, frequent control interventions, surface undulations, crosswind or 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 reacts according to the human biorhythm depending on the time (e.g. taking into account the mid-day low). This has been determined on a representative basis but of course varies from person to person.

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

   In the case of a long period of driving without a break, the sensitivity of the attention assistance system 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 feeling of fatigue and the objective assessment variables determined by the attention assistance system 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-2054-97EAA
	Overview of system components, attention assist		GF54.30-P-9991CA