Apparatus using radio reception for detecting displacement of a vehicle in a direction at right angles to its advancement direction

A terminal apparatus installed on a host vehicle, comprising

• a radio communication condition acquisition unit configured for acquiring respective radio communication conditions of a plurality of radio communication positions on the host vehicle,
• a travel locus/condition information generating unit configured for generating a plurality of sets of travel locus/condition information respectively corresponding to the radio communication positions on the host vehicle, the travel locus/condition information for a radio communication position expressing the radio communication condition at each of respective positions on a travel locus of the host vehicle, the travel locus comprising positions successively attained by the host vehicle when moving along a specific travel direction, and
• a reception map acquisition unit configured for acquiring a plurality of reception maps respectively corresponding to the radio communication positions on the host vehicle, each of the reception maps comprising travel locus/condition information previously generated by the terminal apparatus of the host vehicle or of a vehicle of identical type to the host vehicle when moving along the specific travel direction;
• wherein the terminal apparatus is characterized in that the plurality of radio communication positions on the host vehicle are spaced apart with respect to a direction at right angles to an advancement direction of the host vehicle, and in comprising a relative position estimation unit configured for:
• determining a plurality of respectively different information combinations, each of the information combinations comprising one of the travel locus/condition information sets generated by the host vehicle and one of the reception maps,
• calculating respective magnitudes of agreement degree of the information combinations,
• comparing the respective magnitudes of agreement degree with one another, and
• estimating a position of the host vehicle relative to a reference travel locus, with respect to a direction at right angles to the reference travel locus, based on results of the comparison;
• the reference travel locus comprising a travel locus previously traversed along the travel direction by the host vehicle or vehicle of the same type as the host vehicle when obtaining the travel locus/condition information constituting the reception maps.