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) Comfort multifunction steering wheel 

Attention Assist, general 

The attention assistance system function is integrated into the Electronic Stability Program control unit and it recognizes any occurrences of driver fatigue or an increasing level of inattentiveness (e.g. during long monotonous journeys on freeways and highways) in a vehicle speed range of v = 80 to 180 km/h.

If the attention assistance system function detects appropriate signs indicating driver fatigue or an increasing level of inattentiveness, the driver is prompted to take a break through visual and acoustic warnings. To this end, the driver handling characteristics are registered and evaluated using an algorithm (software).

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

Attention Assist function requirements Circuit 15 ON 

The status of circuit 15 is sent by the electronic ignition lock control unit over the chassis CAN to the Electronic Stability Program control unit.

Function sequence for Attention Assist 

The Attention Assist 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.

Attention Assist function activated 

If the Attention Assist function is active, a coffee cup symbol is shown in the instrument cluster's multifunction display (A1p13).

If the attention assistance system function is switched on, steering patterns that occur more often as fatigue or inattentiveness increase are recorded for the following listed driving conditions:

• Monotonous journey

  (low longitudinal and lateral acceleration)

• No noteworthy external stimulation

(e.g. surface undulations or crosswind)

The driver handling characteristics are also analyzed when the attention assistance system function is switched off. If the attention assistance system function is switched on during a journey, the complete journey after the start is then taken into consideration.

The algorithm registers the following conditions and deems them to be irrelevant for the Attention Assist function:

• 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)

At the start of the journey the algorithm determines an individual driver warning threshold.

The sensitivity of the algorithm adapts to match the driving time and time of day.

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

The multifunction display on the instrument cluster then displays a message: "Attention Assist: Break!" asking the driver to take a 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 n/(S110s6) of the left multifunction steering wheel button group.

The status of the OK button is read in by the steering wheel electronics over the steering LIN by the steering column tube module control unit, and sent over the chassis CAN to the Electronic Stability Program 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 defined by the current time, which is transmitted by the instrument cluster to the Electronic Stability Program control unit via the chassis CAN.

The received time is checked for plausibility on the basis of ambient brightness. To this end the current ambient light intensity is recorded 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:

The yaw rate, lateral and longitudinal acceleration sensor transmits information about vehicle longitudinal/lateral acceleration as well as yaw rate to the Electronic Stability Program control unit over the vehicle dynamics CAN.

Steering movements:

Steering movements are recorded by the steering angle sensor and transmitted to the Electronic Stability Program control unit by the steering column tube module control unit over the chassis CAN.

Vehicle speed:

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

The wheel speeds are recorded by the following components and read in directly by the Electronic Stability Program control unit:

• Left front axle speed sensor
• Right front axle speed sensor
• Left rear axle speed sensor
• Right rear axle speed sensor

Control interventions:

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

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

Control interventions using the control buttons on the radio or the COMAND controller unit are sent over the interior CAN to the front SAM control unit. This sends corresponding information over the chassis CAN to the Electronic Stability Program control unit.

The control interventions on the steering column adjustment, combination switch and the cruise control lever are read-in directly by the steering column tube module control unit.

The steering column tube module control unit also reads in the control interventions from the multifunction steering wheel button groups through the steering wheel electronics over the steering LIN.

The steering column tube module control unit sends this information over the chassis CAN to the Electronic Stability Program control unit.

Also valid is the following function information which can lead to possible function complaints at the customer's:

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 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:

   Attention Assist determines a change in the handling characteristics. 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 system sensitivity:

   Depending on the time, the Attention Assist function responds more sensitively to a curve, which, e.g. maps the afternoon slump (biorhythm). These results are determined representatively, but they may also differ on an individual basis.

5. Influence of driving time on system sensitivity:

   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. significant distraction. 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 system are different.

7. Change in steering ability through other factors:

Next to fatigue or increasing inattentiveness other factors can also significant 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