The importance of position recognition systems for control and monitoring processes is steadily increasing. As dictated by the particular application, very high precision and measuring repetition rate are required for this purpose.

Consequently, work for developing a novel system for commercial applications has been in progress at the Institute of Electrical Information Engineering at the Technical University of Clausthal in cooperation with Siemens AG in M¿nchen. This system will be on display at the joint exhibit on microsystems engineering, Hall 6, stand B02 at the Hannover Exposition (7th to 12th April), Germany.

Non-contact position recognition systems with comparable precision have hitherto not been available on the market. These systems are an innovation for exact navigation in rooms, halls, or machine plants.

A prototype already exists and has been tested successfully. This system corresponds essentially to a self-sufficient GPS on a miniature scale with high spatial accuracy as well as a high measuring rate (real-time capability) and offers additional possibilities for the transmission of data. A system of this kind is well suited for numerous applications, such as:

  • Robot control and regulation by measurement of position in space, for example, of an arm
  • Computer-augmented reality
  • “Virtual mouse” for determining the vector of a pointer, and thus its direction, applicable at exhibitions for selection on large information display screens
  • Surveillance of persons or objects in safety-/security-relevant areas
  • Analysis of trajectories moving targets with simultaneous determination of their velocity by means of the Doppler effect

The system comprises at least three high-frequency transmitting and receiving stations whose spatial coordinates are known. These stations are located in the hall to be monitored, for instance. Furthermore, an active transponder is attached to the object whose coordinates must be determined.

The position recognition is based on the radar principle. For this purpose, a high-frequency signal is transmitted. Upon reception by the active transponder, it is amplified, modulated, and reflected. Finally, it is mixed with the originally transmitted signal in the base station.

After the mixing process, a spectrum with two spectral lines is obtained. The spacing between these two lines is proportional to the distance between the base station and transponder.

From distance measurements by at least three such transmitting and receiving stations, the spatial position of the object to which the transponder is attached can be calculated exactly by a mathematical method.