GF54.30-P-0009CA Attention Assist, Function
GF54.30-P-0009CA Attention Assist, Function
MODEL 207.3/ 4
Function requirements, general
^ Circuit 15 ON
The electronic ignition lock control unit (N73) sends the circuit 15 status over the chassis CAN (CAN E) to the Electronic Stability Program control unit (N30/4) (without code (233) DISTRONIC PLUS) or to the Premium Electronic Stability Program control unit (N30/7) (with code (233) DISTRONIC PLUS).
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 Assist
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 (A1) over the chassis CAN to the Electronic Stability Program control unit.
When the function is switched on, a coffee cup symbol is shown on the multifunction display (A1p13) of the instrument cluster.
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
1 Coffee cup symbol
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 is exceeded, the Electronic Stability
Program control unit sends the request to issue a warning message over the chassis CAN to the instrument cluster.
The instrument cluster's multifunction display then shows the "Attention Assist: Break!" warning message.
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 (S110).
The steering wheel electronics (N135) directly read in the signals from the OK button and sends them over the steering LIN (LIN E1), steering column tube module control unit (N80) and the 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 light brightness is recorded by the rain/light sensor (B38/2).
The front SAM control unit with fuse and relay module (N10/1) imports the data from the rain/light sensor over the wiper/inside rearview mirror LIN (LIN 2) and forwards this to the Electronic
Stability Program control unit over the chassis CAN.
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 velocity is evaluated by the Electronic Stability Program control unit.
The vehicle's yaw behavior is recorded by the yaw rate sensor for lateral and longitudinal acceleration (B24/15), which communicates over the dynamics CAN (CAN H) with the Electronic Stability Program control unit.
Steering movements:
Steering movements are recorded by the steering angle sensor (N49).
The steering column tube module control unit reads in the signals of the steering angle sensor directly 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 the following sensors:
- 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)
The Electronic Stability Program control unit directly reads in the signals from the rpm sensors.
Control interventions at one of the following components disable the detection of steering patterns:
- Radio (A2) (with code (510) Audio 20 incl. CD-changer or with code (523) MB Audio 20 radio) or Radio with Auto Pilot System (A2/56) (with code (511) Audio 50 APS incl. DVD changer or with code (525) MB Audio 50 APS radio) or 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 (driver seat, steering column, mirrors))
- Left multifunction steering wheel button group or right multifunction steering wheel button group (S111)
The control interventions using the control buttons on the radio or the COMAND controller unit are sent by the radio or the COMAND controller unit over the interior CAN (CAN B), front SAM control unit and the chassis CAN to the Electronic Stability Program control unit.
The control interventions on the steering column adjustment switch, combination switch, on the CC lever and on the multifunction steering wheel button groups are read in by the steering column tube module control unit and then 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 System function responds in accordance with the human biorhythm depending on the time (e.g. including the afternoon slump). This is determined representatively, it may however differ 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
