Algorithm derivation and its embedded system realization of speed limit detection for multiple countries

This paper proposes a low-complexity speed limit detection which can not only support different types of speed limit signs for multiple countries, but maintain good detection rate under inclement weathers. The proposed algorithm steps include shape detection to locate speed limit signs, adaptive threshold and digit recognition algorithm which can adapt to different digit fonts to support different types of speed limit signs for multiple countries. We implement the proposed algorithm on both the desktop and the automotive-grade i.MX 6 embedded system. Under D1 resolution (720×480), the proposed system can achieve 150 fps on the desktop and 30 fps on the i.MX 6 embedded system.