I. Introduction
Fatal accidents due to collisions are increasing, so there is a need for improved automobile safety technology to reduce traffic accidents. Furthermore, policies for evaluating the safety of automobiles such as the European New Car Assessment Program (EURO NCAP) are being strengthened. These policies encourage or require the development and installation of safety devices for automobiles and promote research on advanced driver assist systems (ADASs), which are state-of-the-art technology for enhancing driving safety.