A handrail assembly that can be installed on any wall. In one embodiment the method and apparatus utilizes a transmitter or emitter to provide a tracking signal that may be tracked by one or more receivers or detectors. Using at least two pieces of bar magnets, an outer magnet type magnetic circuit is structured in which the magnetic gap comprising an upper plate and a lower plate has a straight section. In the context of a method, device discovery is conducted utilizing a first radio technology. A plurality of process programs in which measurement algorithm is segmentalized are incorporated in the extension unit and a process program is selected according to a command from a personal computer and the selected process program is performed in a predetermined order.