Attention Assist, Function - GF54.30-P-0009RD
Model 172.4 up to model year 2017
Shown on model 172.4
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, then 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 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.
If the Attention Assist function is active a coffee cup symbol is shown in the instrument cluster's multifunction display.
Attention assist function activated
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 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 reads in the signals from the OK button directly and sends them via the steering LIN, the steering column tube module control unit and the chassis CAN to the Electronic Stability Program control unit.
A repeated warning message can be issued at the earliest following expiry of t = 15 min.
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 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 light intensity is detected by the light sensor or by the rain/light sensor.
The front SAM control unit reads in the data from the light sensor or the rain/light sensor via the wiper/inside rear-view 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.
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. On vehicles with code 233 (DISTRONIC PLUS) including model year 2015 or code 239 (DISTRONIC PLUS) model year 2016 or for model 172.475, this is designed as a separate component and it communicates over the vehicle dynamics CAN with the Electronic Stability Program control unit. On vehicles for which the above-mentioned limitation does not apply, the yaw rate sensor for lateral and longitudinal acceleration is integrated in the Electronic Stability Program control unit.
Steering movements:
Steering movements are recorded by the steering wheel angle sensor.
The steering column tube module control unit reads in the signals from the steering wheel angle sensor directly and transmits them to the Electronic Stability Program control unit via chassis CAN.
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 COMMAND 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 at the radio buttons or the COMMAND controller unit buttons are sent by the radio or the COMMAND controller unit via the interior CAN, front SAM control unit and chassis CAN to the Electronic Stability Program control unit.
The steering column tube module control unit reads in the control interventions at the steering column adjustment switch, the combination switch, the cruise control lever and the multifunction steering wheel button groups and sends them via 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:
- 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.
- 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 above).
- 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.
- Influence of time on sensitivity of function:
The attention assistance system function reacts differently depending on the time in accordance with the human biorhythm (e.g. takes into consideration the mid-day low). These results are determined representatively, but they may also differ on an individual basis.
- 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.
- 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.
- 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-2054-97TAA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998RD |