Traffic Sign Recognition is a feature on some vehicles where the vehicle is able to recognise certain traffic
signs along the roadway and inform the driver.
One of the first signs to be recognised by vehicles was speed limit signs. Some of the other traffic signs that
the systems recognise are children/animal crossing, no overtaking, directional signs etc.
How traffic sign recognition works is by using a camera placed somewhere to the front of the vehicle, usually on
the windshield by the interior rear view mirror and points forward.
The camera may be used for several other features and adapted to facilitate the sign recognition.
An ECU/in car computer has been programmed to identify road signs that
is picked up by the camera even when the vehicle is travelling at a high speed.
The system can only identify signs that have been programmed into it based on certain colours, shapes, numbers and
symbols. For example if an arrow pointing upwards and left on a triangular sign is the only sign the vehicle identifies
as a left turn then another sign with the words "left turn" on it would not be recognised.
When the system identifies a traffic sign it will alert the driver via several methods which are mentioned below.
It is also common for traffic sign recognition systems to use information from the
navigation system together with what is captured on the camera to determine the validity of the signs.
- One approach is to display the sign in the heads up display. The sign will be on display
for some time after the sign is passed.
- Another way is to show the sign in the instrument cluster. The sign will also be displayed for some time.
- The system may also give an audible warning on identifying the sign.
- More than one of the above methods may be used to alert the driver.
Satellite navigation systems will have data about speed limits, no overtaking areas, one way streets as well as other
information that will correspond with the traffic signs.
Traffic sign recognition systems are able to identify a variety of signs, from small signs on the side of the road
to large well lit signs above the roadway.
It should be noted that the driver is just informed of the traffic sign to assist in certain decisions to be made while
driving. The driver has the final decision as the vehicle does not try to make any decisions on its own based on traffic signs
such as limiting the speed of the vehicle or preventing the driver from overtaking another vehicle.