Joint interpretation of on-board vision and static GPS cartography for determination of correct speed limit

We present here a first prototype of a “Speed Limit Support” Advance Driving Assistance System (ADAS) producing permanent reliable information on the current speed limit applicable to the vehicle. Such a module can be used either for information of the driver, or could even serve for automatic setting of the maximum speed of a smart Adaptive Cruise Control (ACC). Our system is based on a joint interpretation of cartographic information (for static reference information) with on-board vision, used for traffic sign detection and recognition (including supplementary sub-signs) and visual road lines localization (for detection of lane changes). The visual traffic sign detection part is quite robust (90% global correct detection and recognition for main speed signs, and 80% for exit-lane sub-signs detection). Our approach for joint interpretation with cartography is original, and logic-based rather than probability-based, which allows correct behaviour even in cases, which do happen, when both vision and cartography may provide the same erroneous information. INTRODUCTION AND RELATED WORK Too many accidents are still provoked by excessive speed limit. It would therefore be interesting to offer drivers permanently updated information on current speed limit, so they have more chance to adapt their speed. Alternately, a more advanced very valuable feature would be a smart Adaptive Cruise Control (ACC) automatically adapting vehicle speed to current speed-limit. However, these kinds of functions can be really valuable and of practical use only if the produced speed-limit information is really reliable. Most current GPS navigators now include a function to inform the driver of the supposed current speed-limit, this information extracted from GPS cartographic data is neither always complete nor systematically up-to-date. Moreover, temporary speed limits for road works, and variable speed limits enforced by LED signs, are by definition not included in pre-defined digital cartographic data. Visual traffic sign recognition (TSR) can be quite robust, but it is unavoidable to miss some signs when occlusion by another vehicle (especially truck) occurs. Figure 1. By nature, variable speed limits and roadwork temporary speed limits cannot be obtained from the static cartographic information.