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Diplomarbeit 2004 (DA04): Arbeits-Archiv
 
DA Mar 04/2 - Optical Positioning System for clinical Magnetic Field Tracker
Studierende: Andreas Schneider, schnean1
  Markus Trauffer, traufmar

Betreuer: Ralf Markendorf, mklf

In this thesis a two-dimensional, optical position measuring system was developed. The goal was, to clarify the feasibility, accuracy and requirements to the assigned components and to develop a measuring system as prototype.

The assigned sensors are optical line sensors (PosCon by Baumer electric) which can locate reflecting objects in a fan-like area. The two-sensor measuring system shows a substantially higher accuracy in relation to the system with only one sensor, however the realisation is more expensive. The accuracy of the developed two-sensor measuring system amounts to +/-2mm in the position and +/-0.7? in orientation.

The sensor measured values are converted with a mapping procedure into coordinates. With this procedure a map of the measured values is created on which the sensor measured values as well as their errors and static inaccuracies are registered. Determination of the coordinates of any place on the mapping area is done by an interpolation of the map data. Computing coordinates with a mapping method is very meaningful in two different aspects. On the one hand geometrical inaccuracies of the sensors can be corrected which increases the accuracy in relation to analytic calculation methods. On the other hand mapping allows the sensors to be attached in almost any position whereby the measuring system can be adapted optimally to the spatial conditions.

During the working process mentioned accuracy could be achieved. This is not completely enough for the accuracy of 1mm in the position and 0.2? in orientation which is demanded in the project TULOC (Paul Scherrer Institut). However, investigations of this thesis showed that with more suitable sensors, or different sensor positions, a position measuring system could be realised according to the used principle and with the demanded accuracy.

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