Traffic Sign Recognition (TSR) is a driver support function which can be used to notify and warn the driver which restrictions may be effective on the current stretch of road. Examples for such regulations are ‘speed limit zones’ or ‘no-overtaking’ indications. The system can help the driver to maintain a legal speed, obey local traffic instructions, or urban restrictions.
The system recognizes and interprets various traffic signs, both fixed signs on the road side and variable LED signs overhead, using vision-only information and therefore signs which may be obscured by other vehicles or trees may not be recognized.
Mobileye’s TSR has been available from 2008 on the BMW 7 Series as a vision and Satellite Navigation fusion system, together with Mobileye’s Lane Departure Warning and Intelligent Headlight Control functions. Since 2007 it has been launched with multiple other vehicle makers globally for a range of vehicles, in conjunctions with multiple other Mobileye functions, both as vision-Satellite Navigation fusion and vision only systems from 2011.
Mobileye has developed a Traffic Sign Recognition (TSR) algorithm based on its core competence in vehicle and pedestrian detection. The algorithm shares the attention, classification and tracking framework of those other modules and uses the robust classifiers developed in those applications, trained on different examples.
The system recognizes and interprets various traffic signs using vision-only information and has reached an exceptionally high detection accuracy.. The system uses camera based object recognition and can be developed to compare the data with those coming from digital maps of a navigation system and traffic services. This will offer additional system robustness, especially in cases where the vision system cannot provide the needed information, such entering urban areas which are not marked by traffic signs.
The vision based system has an additional advantage of being able to support navigation systems with the detection of overhead LED based variable speed limit signs, that Satellite Navigation system will not have real-time updates of.
TSR recognizes speed limits in a variety of environmental conditions and also context signs such as, ie ‘bei Nasse’. TSR will be able to recognize country specific signs – which will be implemented as required as part of series development projects.
Moving forward Mobileye is broadening the range of detected signs, in response to the needs of the vehicle makers and from 2011 on wards US speed signs will also be in production in Vision Only mode.
Scenarios and performance
With a VGA resolution imager the system can provide reliable detection for targets with a lateral distance of 10 m, a vertical distance of 7m and at vehicle speeds of up to 250kph. This provides the current system with a very high performance even in challenging high speed situations on multi lane highways.
As high resolution sensors become available for automotive use, Mobileye will be able to increase the effective detection range, as well as detecting more ‘context’ and iconic information.
Speed Limit Indication