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

MODEL 212.0/2 up to 28.2.13 

Function requirements, general 

• Circuit 15 ON

The circuit 15 status is sent by the electronic ignition lock control unit (N73) over the chassis CAN (CAN E) on a model and equipment specific basis to the following control unit:

• Electronic Stability Program control unit (N30/4) (model 212 (except 212.074/077/095/098/274/277/298) without code (233) DISTRONIC PLUS)
• Regenerative braking system control unit (N30/6) (model 212.095/098/298)
• Premium electronic stability program control unit (N30/7) (model 212 (except 212.095/098/298) with code (233) DISTRONIC PLUS, model 212.074/077/274/277)

The control units listed below are designated as the brake system control unit in the following text.

Attention Assist, general 

The attention assistance system function is integrated into the brake system 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 Assist 

The Attention Assist function can be switched on or off in the "Assist." menu in the "Attention Asst." menu level on the instrument cluster (A1).

The status of the attention assistance system function (switched on or off) is sent by the instrument cluster over the chassis CAN to the brake system control unit.

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 ON 

At the start of the journey the brake system 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 brake system control unit sends a request over the chassis CAN to issue a warning message on the instrument cluster.

The multifunction display of the instrument cluster then displays a message prompting the driver to take a break: "Attention Assist: Break!".

The buzzer (A1h1) integrated into the instrument cluster also issues a doubled-up fourfold note.

The warning message can be acknowledged using the OK button (S110s6) of the left multifunction steering wheel button group (S110).

The status of the O. button is read in by the steering wheel electronics (N135) over the steering LIN (LIN E1) by the steering column tube module control unit (N80).

The steering column tube module control unit sends the status of the OK button over the chassis CAN to the brake system control unit.

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

The algorithm for the Attention Assist function mainly processes the following information:

• 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 brake system 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 (B38/2).

The front SAM control unit with fuse and relay module (N10/1) reads in the data of the rain/light sensor over the wiper/inside rearview mirror-LIN (LIN 2) and sends the data over the chassis CAN to the brake system control unit.

If there is a transition between dusk and dawn at an implausible time, an entry is made in the brake system control unit diagnostic memory.

Driving time:

The driving time is determined by the brake system control unit.

Vehicle longitudinal / lateral acceleration and yaw rate:

The yaw rate, lateral and longitudinal acceleration sensor (B24/15) transmits information about vehicle longitudinal/lateral acceleration as well as yaw rate to the brake system control unit over the vehicle dynamics CAN (CAN-H).

Steering movements:

Steering movements are recorded by the steering angle sensor (N49). The steering column tube module control unit reads in the steering angle sensor signals and transmits them to the brake system control unit over the chassis CAN.

Vehicle speed:

The vehicle speed is calculated by the brake system control unit using the wheel speeds.

The wheel speeds are recorded by the following components and directly read in by the brake system control unit:

• Left front axle rpm sensor (L6/1)
• Right front axle rpm sensor (L6/2)
• Left rear axle rpm sensor (L6/3)
• Right rear axle rpm sensor (L6/4)

Control interventions:

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

• Radio (A2) (with code (510) Audio 20 with CD changer or with code (523) MB Audio 20 radio)
• Radio with auto pilot system (A2/56) (with code (511) Audio 50 APS with DVD changer or code (525) MB Audio 50 APS radio)
• COMAND controller unit (A40/3) (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 (S4)
• CRUISE CONTROL lever (S40/4)
• Steering column adjustment switch (S59) (with code (275) Memory package for electrically adjustable front seats and without code (443) Steering wheel heater) or steering column adjustment switch (S59/1) (with code (275) Memory Package for electrically adjustable front seats and code (443) Steering wheel heater)
• Left multifunction steering wheel button group and right multifunction steering wheel button group (S111)

Control interventions are recorded as follows:

The radio or the radio with autopilot system or the COMAND controller unit sends the information on the control interventions to the respective control buttons over the interior CAN (CAN B), front SAM control unit and the chassis CAN to the brake system control unit.

The control interventions on the steering column adjustment switch, combination switch, on the cruise control lever and the multifunction steering wheel button group area read in by the steering column tube module control unit and it sends them over the chassis CAN to the brake system 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 v = 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, but it can vary on an individual basis.

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, location of components		GF54.30-P-0009-02FL
	Attention Assist electrical function schematic		PE54.71-P-2054-97DAA
	Attention assist, block diagram		GF54.30-P-0009-03FL
	Overview of system components, attention assist		GF54.30-P-9991FL