Traffic Sign Assist, Function - GF54.30-P-0010RR
Model 190
With Code 513 (Traffic Sign Assist)
Shown up to 30.11.2018
Shown as of 01.12.2018
Function requirements in general
- Circuit 15R ON
The electronic ignition lock control unit sends the circuit 15 status via the interior CAN, front SAM control unit and chassis CAN 2 to the multifunction camera.
Traffic Sign Assist, general
The Traffic Sign Assist is implemented in the multifunction camera. The multifunction camera is attached to the inside of the windshield and detects sign posted speed limits (e.g. at the edge of the road, on overhead signs or at 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. "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.
The following traffic signs are recorded and evaluated on the stretch of road being driven on by the vehicle.:
- Speed limits including additional signs along with the corresponding termination signs
- No overtaking signs and their termination
- No entry signs
The detected traffic signs are shown in the instrument cluster and on the Audio/COMAND display. The display in the instrument cluster can be switched on or off on the instrument cluster (up to 30.11.2018) or using the head unit (as of 01.12.2018).
If the display of the detected traffic signs was deactivated, the wrong-way warning function and the display for speed limit and no passing signs remain active.
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)
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 multifunction camera evaluates among others the following input factors:
- Signal "Engine running" or "Drive train operational"
- Location data
- Direction of travel, vehicle speed and yaw rate
- Steering wheel angle
- Windshield wiper active
- Outside temperature
"Engine running" or "Drive train operational" signal:
The ME-SFI control unit sends the "engine running" or "drivetrain operational" signal via the drive train CAN, powertrain control unit, chassis CAN 1, the front SAM control unit and chassis CAN 2 to the multifunction camera.
Location data:
The location 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 head unit sends the location data via the user interface CAN, AMG gateway control unit, interior CAN, front SAM control unit and chassis CAN 2 to the 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 turn rate, lateral acceleration and longitudinal acceleration sensor. The yaw rate sensor for lateral and longitudinal acceleration transmits appropriate values via the dynamics CAN to the Electronic Stability Program control unit.
The Electronic Stability Program control unit sends all relevant information to the multifunction camera via chassis CAN 1, the front SAM control unit and chassis CAN 2.
Steering wheel angle:
Up to 30.11.2018
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 angle to the multifunction camera via chassis CAN 1, the front SAM control unit and chassis CAN 2.
As of 01.12.2018
The steering angle is recorded by the steering wheel angle sensor. The steering column tube module control unit reads in the signals of the steering wheel angle sensor directly and sends information on the steering wheel angle over the AMG FlexRay, AMG gateway control unit, interior CAN, front SAM control unit and the suspension CAN 2 to the multifunction camera.
Windshield wiper active:
The front SAM control unit controls the windshield wiper system. With the windshield wipers switched on, the front SAM control unit sends the "windshield wipers active" status via chassis CAN 2 to the multifunction camera.
Outside temperature:
The outside temperature is recorded by the outside temperature sensor. The front SAM control unit reads in the signal from the outside temperature sensor directly, uses it to calculate the outside temperature and sends the outside temperature to the instrument cluster via the interior CAN, AMG gateway control unit and user interface CAN. The instrument cluster calculates the outside temperature to be displayed and sends it over the user interface CAN, AMG gateway control unit, front SAM control unit and chassis CAN 2 to the multifunction camera.
To prevent the windshield from fogging up in the multifunction camera's field of view, this area of the windshield is heated.
Traffic Sign Assist
At a horizontal angular coverage of 46° the multifunction camera records pictures of the traffic signs over or at the side of the road during the journey. 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 evaluates both circular and square contours. Speed limits, prohibitory and derestriction signs including additional restrictions in countries with signage according to the Vienna convention are accordingly recorded. 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 multifunction camera and a permissible maximum speed with additional restriction "in the wet" is registered, the detected permissible maximum speed is shown in the instrument cluster.
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 evaluation of the data, the detected traffic signs are shown in the instrument cluster and in 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.
If the multifunction camera detects a no entry sign at the entrance to 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 instrument cluster and in the Audio/COMAND display. Additionally, the "Check direction of travel!" warning message is displayed in the instrument cluster and a warning tone is issued over the instrument cluster speaker, which is actuated directly by the instrument cluster.
The multifunction camera sends corresponding requests to display the currently detected traffic sign and a warning message to the instrument cluster and the head unit via chassis CAN 2, the front SAM control unit, interior CAN, AMG gateway control unit and user interface CAN. The head unit actuates the audio/COMAND display over the telematics CAN and sends the corresponding data over the LVDS line (up to 30.11.2018) or over the HSVL line (as of 01.12.2018).
The acoustic warning can be acknowledged at the earliest after 5 s.
In the event of a fault, the following messages are shown in the instrument cluster:
- "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"
Traffic signs recognized by the multifunction camera (example displays)
Representation of derestriction signs
The following events cause the derestriction sign to be displayed (F):
- Passing by a derestriction sign (F)
- Driving by a derestriction sign with a speed value (G, G1), if no traffic sign with a speed value was previously detected
The following event leads to the display of a derestriction sign (H):
- Driving by a derestriction sign with speed value (G, G1), whose value deviates from the speed value of the traffic sign (H1) documented in the prior history
The following event leads to the display of a derestriction sign (I):
- Driving by a derestriction sign for no passing (I), if the no passing sign was previously detected (I1)
When driving by a derestriction sign (speed limitation or no passing), the derestriction sign is shown for 5 s. The valid traffic regulation is then shown on the instrument cluster and on the Audio/COMAND display.
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, detected by the multifunction camera
- Vehicle movement and yaw behavior
- Location data from the head unit
The attributes verified in the digital card of the navigation system are also evaluated.
The location 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 location data is used to evaluate the national availability. The national availability may be able to be extended and therefore it matches the current software release.
If the location data cannot be evaluated (e.g. no GPS signals), the Traffic Sign Assist is switched off after a travel distance of s = 30 km.
If the multifunction camera does not detect any speed limits (e.g. if the windshield is dirty), the values verified in the digital map of the navigation system are shown. If this condition is maintained for more than 10 minutes, the multifunction camera changes to the "Blockade" mode and the traffic signs display is deactivated. If, later on, a traffic sign is detected again (e.g. owing to a reduction in the degree of windshield fogging), the "Blockade" mode is deactivated again.
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 location 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 location data.
With a change from a non-built-up area to a built-up area as defined by the markings for buildings on the navigation system map, the display of the last identified speed limit is canceled. As the town/village limits do not always match the built-up area markings from the navigation system 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 instrument cluster and the Audio/COMAND display:
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 system map.
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 picture cannot be uniquely identified as a traffic sign, the speed value that is filed in the digital navigation system map is then shown.
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 United Kingdom, the Netherlands and Belgium.
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 recording angle (a) of the multifunction camera is 46°.
The vertical angle of vision of the multifunction camera is limited. Traffic signs on overhead gantries are only interpreted reliably up to a vehicle speed of 160 km/h.
In order to keep recognition certainty homogeneous over all vehicle speed ranges, the evaluation window of the multifunction camera is downsized as the vehicle speed increases. The consequence of limiting the evaluation window of the multifunction camera is that traffic signs installed low down, for example signs used in construction sites, are "missed" if they are passed at high speed.
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.
Unfavorably designed back-end sections of commercial vehicles may be interpreted as derestriction signs by mistake (left picture).
Signage on the back-end section of commercial vehicles may be interpreted as traffic signs by mistake (right picture).
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-2066-97HBA | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998RR |