Traffic Sign Assist, Function - GF54.30-P-0010GWM
Model 463 (except 463.342)
as of Model year 2019
Function requirements in general
- Terminal 15R On:
The electronic ignition lock control unit transmits the circuit status of circuit 15 to the mono multifunction camera via the suspension FlexRay.
Traffic Sign Assist, general
The Traffic Sign Assist is implemented in the mono multifunction camera. The mono multifunction camera on the inner side of the windshield detects the speed limits sign-posted, for example at the edge of the road, on sign gantries or in construction sites. The captured data is compared with the information of the navigation system and displayed both in the instrument cluster and in the map view on the Audio/COMAND display. "No passing" zones and the associated de-restriction signs are also recorded and displayed. For no-entry zones with corresponding signage, the instrument cluster also issues an optical warning and a warning tone.
Whether both an optical warning and a warning tone are issued when a speed limit is exceeded can be set via the head unit. The following options are available for navigating in the control menu:
- Navigation can be performed on the Audio/COMAND control panel. The Audio/COMAND control panel transmits the relevant control signals via the telematics CAN to the head unit.
- Navigation can be operated via the touchpad. The touchpad sends the relevant operation signals to the head unit via the telematics CAN.
- 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 head unit finger navigation pad and the "Back" button transmit the relevant control signals via the steering wheel electronics, the steering wheel CAN, the steering column tube module control unit, the suspension FlexRay, the electronic ignition lock control unit and the user interface CAN to the head unit.
- The operating menu can be called up on the upper control panel control unit via the vehicle button. The vehicle button status is sent by the upper control panel control unit over the LCP-LIN, Audio/COMAND control panel and the telematics CAN to the head unit.
The head unit transmits the status of the operating mode to the mono multifunction camera via the user interface CAN, the electronic ignition lock control unit and the suspension FlexRay.
The driver can select the following operating modes:
- Visual warning
- Visual warning and warning tone
- Off
The following traffic signs are recorded and evaluated by the mono multifunction camera on the stretch of road the vehicle is driving on:
- Speed limits including additional signs
- No overtaking signs and their termination
- No entry signs
The registered traffic signs are shown on the multifunction display of the instrument cluster and on 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 several speed limits are detected, the lowest speed limit is displayed.
Shown on Audio/COMAND display, system language German (the detected traffic signs are shown on a country-specific basis)
12 Recognized speed limit (where applicable. including supplementary sign)
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 evaluates, among other things, the following input factors:
- 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
"Engine running" or "Drive train operational" signal:
The CDI control unit or the ME-SFI control unit transmits the "Engine running" or "Drivetrain operational" signal to the mono multifunction camera via the drive CAN, the powertrain control unit and the suspension FlexRay.
Map data:
The map data is used for checking the plausibility of the object detected by the mono multifunction camera as well as for fading out displayed speed limits when the vehicle is driven into built-up areas.
The head unit transmits the map data to the mono multifunction camera via the user interface CAN, the electronic ignition lock control unit and the suspension FlexRay.
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 ESP® control unit transmits all relevant information to the mono
multifunction camera via the suspension FlexRay.
Steering wheel angle:
The steering angle is recorded by the steering wheel angle sensor.
The steering column tube module control unit directly reads in the signals of the steering wheel angle sensor and transmits information on the steering wheel angle to the mono multifunction camera via the suspension FlexRay.
Windshield wiper active:
The front SAM control unit controls the windshield wiper system. With the windshield wipers switched on, the front SAM control unit transmits the status "Windshield wipers active" to the mono multifunction camera via the interior CAN, the electronic ignition lock control unit and the suspension FlexRay.
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 displayed outside temperature and transmits it to the mono multifunction camera via the user interface CAN, the electronic ignition lock control unit and the suspension FlexRay.
Trailer recognition:
If a trailer is detected, the trailer recognition control unit transmits the "Trailer detected" status to the mono multifunction camera via the interior CAN, the electronic ignition lock control unit and the suspension FlexRay.
Function sequence for Traffic Sign Assist
At a horizontal angular coverage of S . = 46° the mono multifunction camera records pictures during the journey of the traffic signs over or at the side of the roadway. Traffic Sign Assist is continuously active in the background. In other words, the corresponding traffic signs are constantly recorded and evaluated by the mono multifunction camera.
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 picture recognition module of the mono multifunction camera assigns a specific credibility to all results.
The national regulations for the design and attachment of traffic signs are taken into account for this.
The mono multifunction camera records all picture objects and evaluates circular as well as square contours. Speed limits, prohibitory and de-restriction 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 wipers active" status is received by the mono multifunction camera and a speed limit with an additional restriction "in the wet" is registered, the detected speed limit is displayed in the instrument cluster. The speed limit is not viewed to be relevant as long as the "Windshield wipers 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 mono multifunction camera also compiles the information about a speed limit to form an event if the information is contradictory.
The mono multifunction camera transmits corresponding requests to display the currently detected traffic sign and a warning message via the suspension FlexRay, the electronic ignition lock control unit and the 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.
If the mono multifunction camera detects a no entry sign when entering a freeway or expressway in the opposite direction to the direction of travel (motorist driving the wrong way scenario), the no entry sign is shown on the multifunction display of the instrument cluster and on 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 warning tone can be quit at the earliest after t = 5 s.
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. mono 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 mono multifunction camera (example displays)
Representation of de-restriction signs
The following events result in the de-restriction sign being shown (picture J):
- Passing by a de-restriction sign (picture F) and no further speed limits
In no passing areas, the prohibition sign is removed from the display when a no passing de-restriction signs is passed (picture I).
In addition, the mono multifunction camera evaluates information on the vehicle surroundings and on the vehicle's own movement.
These include:
- Distance and angle to other road users and objects recorded by the mono 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 is 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 mono multifunction camera cannot be evaluated and cannot be used to display on 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 mono multifunction camera. This type of display is mainly used in The Netherlands and Belgium.
Horizontal angle of vision of mono multifunction camera
The horizontal angle of vision of the mono multifunction camera is limited. Traffic signs erected immediately after junctions, which the vehicle turns into, can be "missed" by the mono multifunction camera.
The horizontal angular coverage of the mono multifunction camera is 4 a = 46°.
Resolution of mono multifunction camera
The resolution of the mono multifunction camera is limited. Traffic signs on wide or multi lane roads can be "missed" as they do not reach the size required for clear identification in the evaluation window of the mono multifunction camera.
The sensitivity and dynamics of the mono 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 mono multifunction camera are fixed.
As a result recorded objects are represented with a movement blur depending on the exposure time.
This motion blur and the sensitivity of the mono 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 de-restriction 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-2066-97ZGA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998GWM |