Various techniques have been proposed for detecting a position of an own-vehicle along a traveled path. Patent literature 1 discloses a technique for estimating a position of the own vehicle along a traveled path not using any sensors for observing the external environment, such as a GPS device and a camera, but using odometry information of the own vehicle regarding a vehicle speed, a yaw angle, a steering angle and others. The estimation of the position of the own-vehicle along the traveled path may be utilized in various systems for improving driving safety, such as a lane departure warning system and a lane keeping system.