US Patent 7317388 Position detection system for mobile object

A position detection system for measuring a position of a mobile object traveling throughout a controlled area, the position detection system includes a tag, which is provided on the mobile object, a detector, which obtains object position information which indicates the position of the mobile object, object position information includes direction information and distance information relative to the detector of the mobile object, and the detector travels throughout the controlled area, and a base station which obtains detector position information which indicates the position of the detector, detector position information includes an absolute position and angle within the controlled area of the detector, in order to measure the position within the controlled area of the mobile object based on object position information and detector position information.