Traffic Sign Assist, Function - GF54.30-P-0010LFM
Model 217, 222
as of model year 2018
with code 513 (Traffic Sign Assist)
Shown on model 217, 222
Function requirements, general
- Terminal 15R On:
The electronic ignition lock control unit sends the circuit 15 status over the chassis FlexRay to the stereo multifunction camera or over the periphery CAN to the mono multifunction camera.
Traffic Sign Assist, general
The multifunction camera mounted to the inside of the windshield detects the speed limits posted, for example at the edge of the road, on sign gantries or in construction sites. Their data is compared with the information of the navigation system and displayed both in the instrument cluster and in the navigation map view. "No passing" zones and the associated derestriction signs are also recorded and displayed. For no-entry zones with corresponding signage, a visual warning and warning tone are also issued in the instrument cluster.
A visual warning and a warning tone can also be issued when a speed limit is exceeded, and can be selected and configured using the head unit. The following options are available for navigating in the control menu:
- With code 448 (Touchpad) navigation can be operated using the Audio/COMAND control panel. The corresponding control signals are sent by the Audio/COMAND control panel (except code 446 (Touchpad only)) over the telematics CAN to the head unit.
- With code 446 (Touchpad only) or code 448 (Touchpad), navigation can be performed using the touchpad. The corresponding control signals are sent by the touchpad (with code 446 (Touchpad only) or code 448 (Touchpad)) over the telematics CAN to the head unit.
- Navigation can be performed by voice control. The driver hands-free system microphone is read directly by the head unit.
- Navigation can be performed via the head unit finger navigation pad and the "Back" button on the steering wheel. The corresponding control signals are sent by the finger navigation pad head unit and the Back button over the steering wheel electronics, steering wheel CAN, steering column tube module control unit, suspension FlexRay, electronic ignition lock control unit and the user interface CAN to the head unit.
- With code 448 (Touchpad) the control menu can be activated with the "CAR" button on the Audio/COMAND control panel. The status of the "CAR" button is sent by the Audio/COMAND control panel over the telematics CAN to the head unit.
- With code 446 (Touchpad only) the control menu can be activated using the "CAR" button on the lower control panel. The status of the "CAR" button is sent by the lower control panel over the LCP-LIN, touchpad (with code 446 (Touchpad only)) and the telematics CAN to the head unit.
The head unit sends the status of the operating mode over the user interface CAN, electronic ignition lock control unit and the chassis FlexRay to the stereo multifunction camera or over the user interface CAN, electronic ignition lock control unit and the periphery CAN to the mono multifunction camera.
The driver can select the following operating modes:
- Visual warning
- Visual warning and warning tone
- Off
Traffic Sign Assist is implemented to match the equipment into the mono multifunction camera or into the stereo multifunction camera.
The following traffic signs are recorded and evaluated on the stretch of road being driven on by the vehicle.:
- Speed limits including additional signs
- No overtaking signs and their termination
- No entry signs
The detected traffic signs are shown on the instrument cluster's multifunction display, in the head-up display (with code 463 (Head-up display)) and in the Audio/COMAND display. The display in the instrument cluster's multifunction display can switched on or off on the head unit.
Display in instrument cluster (depiction of the detected traffic sign is country-specific)
A maximum of two speed limits and an additional traffic sign are shown at the same time. If more speed limits are detected, the lowest speed limits are displayed.
Shown on Audio/COMAND display, system language German (the detected traffic signs are shown on a country-specific basis)
The display in the Audio/COMAND display is only shown in the Navigation system map view, and it can be switched on or off using the head unit menu.
The mono multifunction camera or the stereo multifunction camera evaluates the following input factors among other things:
- Signal "Engine running" or "Drive train operational"
- Map data
- Direction of travel, vehicle speed and yaw rate
- Steering wheel angle
- Windshield wiper active
- Outside temperature
- Trailer recognition (with CODE 550 (Trailer hitch))
"Engine running" or "Drive train operational" signal:
The CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or "Drive train operational" signal via drive train CAN, powertrain control unit and chassis FlexRay to the stereo multifunction camera or via drive train CAN, powertrain control unit and periphery CAN to the mono multifunction camera.
Map data:
The map data is used for checking the plausibility of the object detected by the multifunction camera as well as for fading out displayed speed limits when the vehicle is driven into built-up areas. The map data are sent by the head unit over the user interface CAN, electronic ignition lock control unit and the chassis FlexRay to the stereo multifunction camera or over the user interface CAN, electronic ignition lock control unit and the periphery CAN to the mono multifunction camera.
Direction of travel, vehicle speed and yaw rate:
Information on direction of travel and vehicle speed are derived from the wheel speed and wheel rotation direction signals.
The yaw behavior is detected by the acceleration sensor integrated into the Supplemental Restraint System control unit. The supplemental restraint system control unit sends the corresponding values via the vehicle dynamics CAN to the Electronic Stability Program control unit.
The Electronic Stability Program control unit sends all relevant information via chassis FlexRay to the stereo multifunction camera or via chassis FlexRay, electronic ignition lock control unit and periphery CAN to the mono multifunction camera.
Steering wheel angle:
The steering angle is 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 sends information about the steering wheel angle via the chassis FlexRay to the stereo multifunction camera or via the chassis FlexRay, electronic ignition lock control unit and periphery CAN to the mono multifunction camera.
Windshield wiper active:
The front SAM control unit controls the windshield wiper system. With the windshield wiper switched on, the front SAM control unit sends the "Windshield wiper active" status via the interior CAN, electronic ignition lock control unit and chassis FlexRay to the stereo multifunction camera or via the interior CAN, electronic ignition lock control unit and periphery CAN to the mono multifunction camera.
Outside temperature:
The outside temperature is recorded by the outside temperature sensor. The front SAM control unit reads in the outside temperature sensor signal directly, uses this to calculate the outside temperature and sends this via interior CAN, electronic ignition lock control unit and user interface CAN to the instrument cluster. The instrument cluster calculates the outside temperature displayed and sends this over the user interface CAN, electronic ignition lock control unit and chassis FlexRay to the stereo multifunction camera or over the user interface CAN, electronic ignition lock control unit and periphery CAN to the mono multifunction camera.
Trailer recognition (with code 550 (Trailer hitch)):
If a trailer is detected, the trailer recognition control unit sends the "Trailer detected" status over the interior CAN, electronic ignition lock control unit and the chassis FlexRay to the stereo multifunction camera or over the interior CAN, electronic ignition lock control unit and the periphery CAN to the mono multifunction camera.
Function sequence for Traffic Sign Assist
At a horizontal angular coverage of ∠ = 46° the multifunction camera records pictures during the journey of the traffic signs over or at the side of the road. Traffic Sign Assist is continuously active in the background. In other words, the corresponding traffic signs are permanently recorded and evaluated by the multifunction camera [MFK]. The recorded picture data are sent to the integrated picture recognition module which compares them against the stored data records and assigns the traffic signs to the respective valid road traffic regulations. The multifunction camera's picture recognition module assigns credibility to all results.
The national regulations for the design and attachment of traffic signs are taken into account for this.
The multifunction camera records all picture objects and evaluates circular as well as square contours. Speed limits, prohibitory and derestriction signs including additional restrictions in countries with signage according to the Vienna convention, in the USA and Canada are accordingly detected. Non-relevant signs (supplementary signs that, e.g. are relevant for a turnoff lane) are suppressed. If the navigation system is active, supplementary signs will be shown immediately if they are relevant for the currently active navigation. Possible supplementary signs can be. Restrictions in the wet or for trailer operation. If, for example, the "Windshield wiper active" status is received by the multifunction camera and a speed limit with additional restriction "in the wet" is detected, the detected speed limit is shown in the instrument cluster. The speed limit is not regarded as relevant as long as the "Windshield wiper active" status is not read in.
Supplementary signs not relevant for passenger cars (e.g. speed limits for trucks) will not be shown. The number of these traffic signs amounts to approx. 10 % of all traffic signs. After evaluating the data, the detected traffic signs are shown on the instrument cluster's multifunction display and on the Audio/COMAND display. Information about the currently permissible speed or the currently valid prohibitions is thus available to the driver.
The multifunction camera also combines the information about speed limit to form an event if the information is contradictory.
Vehicles except code 23P (Driving Assistance Package):
The mono multifunction camera sends corresponding requests to display the currently detected traffic sign and a warning message via the periphery CAN, electronic ignition lock control unit and user interface CAN to the instrument cluster and the head unit.
Vehicles with code 23P (Driving Assistance Package):
The stereo multifunction camera sends corresponding requests to display the currently detected traffic sign and a warning message via the chassis FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster and the head unit.
The head unit actuates the Audio/COMAND display via the telematics CAN and transmits the relevant data over the HSVL line.
Vehicles with code 463 (Head-up display):
The instrument cluster sends the corresponding data over the HSVL line to the head-up display. The head-up display projects the corresponding data onto the windshield in the driver's field of view.
If the multifunction camera detects a no entry sign if the vehicle is driven onto a freeway or expressway in the opposite direction to the direction of travel (wrong-way driver scenario), the no entry sign is shown in the multifunction display of the instrument cluster and in the Audio/COMAND display. A "Check direction of travel!" warning message is displayed in the multifunction display and a warning tone is also issued over the instrument cluster speaker, which is actuated directly by the instrument cluster.
The acoustic warning message can be acknowledged after t = 5 s at the earliest.
In the event of a fault, the following messages are shown on the multifunction display:
- "System currently not available" (e.g. camera field of view fogged up)
- "System nonfunctional" (e.g. multifunction camera or navigation system malfunction)
- "Field of view camera blocked, Traffic Sign Assist nonfunctional"
Display on the instrument cluster
Traffic signs recognized by the multifunction camera (example displays)
Representation of derestriction signs
The following events cause the derestriction sign to be displayed (J):
- Passing by a derestriction sign (F) and no further speed limits
In no passing areas, the prohibition sign is removed from the display when a no passing derestriction signs is passed (I).
In addition the multifunction camera evaluates information on the area around the vehicle and on the vehicle's own movement.
These include:
- Distance and angle to other road users and objects recorded by the multifunction camera itself
- Vehicle movement and yaw behavior
- Head unit map data
The attributes verified in the digital card of the navigation system are also evaluated.
The map data are used to evaluate the national availability. The national availability may be able to be extended and therefore it matches the current software release.
Because speed limits are subject to alteration, the digital map data has to be regularly updated.
Information on the classification of roads and regional development is deduced from the map data provided by the head unit. By this means the system recognizes that the vehicle is leaving a road for which a speed limit identified earlier was displayed. Since the picture recognition is unable to cancel the display of a speed limit identified outside a town/village when passing a town/village entry sign, use is made of the map data.
When changing from an undeveloped area to a built-up area, the speed limit of the map data are used. As the town/village limits do not always match the built-up area markings from the navigation map, the display of the last detected speed limit may be faded out too soon or may continue to be shown in the built-up area.
Situations which lead to a failed cancellation or superfluous cancellation of this display are shown in the following pictures:
Representation of town/village limits and built-up area limits
Function information and system limits
Below is a list of example situations in which the pictures recorded by the multifunction camera cannot be evaluated and cannot be used for display in the multifunction display and the Audio/COMAND display:
Highway entry/exit signs
Speed limits marked by town/village entry and town/village exit signs or by freeway start and finish signs are not recorded. These traffic signs however, are filed through the road definition feature (e.g. freeway) in the digital navigation map.
Changing traffic signs
Electronically actuated changing traffic signs can be "missed" or interpreted incorrectly. In the event of changing traffic signs that are actuated by pulses or flashes, there may be difference to the picture recording's permanent cycle time, depending on the actuated frequency of the changing traffic signs. As a result only fragments of the changing traffic signs will be recognized.
If the image cannot be uniquely identified as a traffic sign, the speed value that is stored in the digital navigation map is then shown.
Changing traffic signs without circular ring
To enable the detection of changing traffic signs on which the outer circular ring is missing, special detectors have been implemented in the multifunction camera. This type of display is mainly used in The Netherlands and Belgium.
Horizontal angle of vision of multifunction camera
The horizontal angle of vision of the multifunction camera is limited. Traffic signs erected immediately after junctions, turnoffs which the vehicle takes, can be "missed" by the multifunction camera.
The horizontal angular coverage of the multifunction camera is ∠ a = 46°.
Resolution of multifunction camera
The resolution of the multifunction camera is limited. Traffic signs on wide or multilane roads can be "missed" as they do not reach the size required for clear identification in the evaluation window of the multifunction camera.
The sensitivity and dynamics of the multifunction camera are limited.
This results in traffic signs not being recognized under the following conditions:
- Traffic signs with low contrast
- Extreme oncoming lights or lights from the rear
- Low levels of lighting, darkness
The focus and alignment of the multifunction camera are fixed. As a result recorded objects are represented with a movement blur depending on the exposure time.
This movement blur and sensitivity of the multifunction camera limit its usefulness at night. The result of the fixed focus and static alignment is that the traffic signs to be recorded must be completely visible in a small observation time window.
Back-end sections of commercial vehicles - design
Unfavorably designed back-end sections of commercial vehicles may be interpreted as derestriction signs by mistake.
Back-end sections of commercial vehicles - labeling
Signage on the back-end section of commercial vehicles may be interpreted as traffic signs by mistake.
During an update or a reset procedure for the head unit, the navigation system data are not available so that fault messages may occur in an individual case.
| Electrical function schematic, traffic sign assist | PE54.30-P-2066-97SEB | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998LFM |