APPARATUS USING RADIO RECEPTION FOR DETECTING DISPLACEMENT OF A VEHICLE IN A DIRECTION AT RIGHT ANGLES TO ITS ADVANCEMENT DIRECTION

An apparatus installed on a host vehicle derives travel locus/condition information relating each of a plurality of reception positions on the vehicle to a corresponding reception condition (e.g., received signal strength), and updates the information at each of successive positions along a travel locus of the vehicle. The currently obtained information is compared with reference travel locus/condition information previously obtained by travel along a reference travel locus, in the same travel direction, by the host vehicle or similar vehicle. Degrees of similarity between the currently obtained information and the reference information are evaluated, and the results used to detect changes in position of the host vehicle along a direction at right angles to its advancement direction.