G12�Driver�Assistance�Systems
11.�Road�Sign�Recognition
47
Additional�information�is�requested�by�the�system�from�the�vehicle�electrical�system�before�displaying
speed�limits�or�no�overtaking�signs�with�restrictive�validity.�For�example,�for�"in�wet�weather"�signs�the
status�of�the�wiper�is�evaluated�or�for�"in�frost/snow"�the�temperature�value�of�the�outside�temperature
sensor�is�evaluated.
Temporal�restrictions�of�the�speed�limit�or�no�overtaking�sign�can�only�be�evaluated�correctly�if�the
validity�duration�is�stored�in�the�navigation�map�and�the�clock�is�set�correctly�in�the�vehicle.�Otherwise,
the�speed�limit�or�the�no�overtaking�sign�is�displayed�as�currently�valid.
The�trailer�signal�for�vehicles�in�trailer�towing�is�not�evaluated�for�the�display�of�speed�limits�as�the
speed�limits�for�vehicles�with�trailer�are�specific�to�the�national�market�and�dependent�on�the�trailer
type.
Other�additional�characters�are�not�recognized.�The�speed�limit�or�the�no�overtaking�sign�is�then
displayed�as�currently�valid�without�the�interpretation�of�the�additional�character.
Road�signs�on�parallel,�branching-off�or�merging�roads�and�on�exits
Parallel�roads�are�not�recognized,�neither�by�the�KAFAS�stereo�camera�nor�with�the�help�of�the
navigation�map.�Signs�on�these�roads�can�be�recognized�and�displayed�as�speed�limits�or�no
overtaking�for�the�current�road.
Speed�limits�and�no�overtaking�signs�for�forking�or�emerging�roads�are�generally�also�assumed�and
displayed�for�the�current�road.
Speed�limits�for�exits�off�highways�with�or�without�an�arrow�as�an�additional�character�are�generally
evaluated�correctly�and�suppressed�in�the�display�if�driven�past.�This�is�only�the�case�if�the�data�on�the
navigation�map�is�up-to-date.
In�the�case�of�gantry�signs�on�the�highway�with�different,�lane-dependent�speed�limits,�the�speed�limit
which�is�closest�to�the�vehicle's�lane�is�displayed.�There�is�no�adaptation�of�the�display�after�a�later�lane
change.
Information�signs�in�the�road�sign�surroundings
Information�signs�with�speed�limits�or�no�overtaking�stipulations,�such�as�at�border�crossing�points
with�information�on�the�different�legal�maximum�speeds�for�single-lane�roads�and�highways,�may�be
incorrectly�recognized�as�currently�valid�and�displayed.�The�same�applies�to�information�signs�with
different�color�configurations,�for�example�for�minimum�or�recommended�speeds.
Stickers�on�vehicles
Stickers�with�a�speed�limit�on�vehicles�ahead�or�overtaken,�such�as�trucks,�buses,�trailers�or
construction�machinery,�etc.,�may�be�incorrectly�recognized�as�a�currently�valid�speed�limit�and
displayed.
Town/city�limits
If�the�sign�for�the�entrance�to�a�village/town�is�not�clearly�recognized�and�the�data�from�the�navigation
map�is�not�up-to-date,�the�speed�limit�at�the�entrances�to�and�exits�from�villages/towns�may�be
displayed�incorrectly.
Legal�changes
If�legally�prescribed�maximum�speeds�change,�then�these�are�only�available�after�a�software�update.
Up�until�the�update�the�original,�current�but�no�longer�valid�speed�limits�are�displayed.
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