This article presents a method for real-time control of vehicle trajectory on a highway based on an on-board vision system using a single camera. The system has been designed to avoid damage (e.g., due to a sleepy driver). The method is based on the real-time extraction of the lateral vehicle location, which is used to determine the vehicle trajectory. Furthermore, the system is able to correct possible bad road tracking in order to have a complete autonomy. The whole system has been implemented on a single TMS320C50 DSP-based card. Reliable results have been obtained on the highway over several hundreds of kilometers at low and high speeds reaching more than 130 km/hr.