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MECHANICALLY ASSISTED SEED CALCULATION FOR ELECTROMAGNETIC TRACKER

IP.com Disclosure Number: IPCOM000126876D
Publication Date: 2005-Aug-05
Document File: 4 page(s) / 27K

Publishing Venue

The IP.com Prior Art Database

Abstract

C-arm fluoroscope applications (with the electromagnetic sensor mounted on the fluoroscope X-ray detector), the mechanical geometry of the C-arm constrains the movement of the electromagnetic sensor. This is particularly true if the moving parts of the C-arm contain encoders which report the positions or orientations of the moving parts. This mechanical information (suitably transformed to tracker coordinates) can be used as the seed in the electromagnetic tracker position-and-orientation calculation. Similarly, data from ultrasonic, optical, or other tracking systems can be used as a seed for the electromagnetic tracker postion-and-orientation calculation. These solutions are particularly useful for the first cycle's calculation, when the previous cycle's results are not available.

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MECHANICALLY ASSISTED SEED CALCULATION FOR ELECTROMAGNETIC TRACKER

BACKGROUND OF THE INVENTION

A known method of tracking position and orientation of magnetic sensor using a discretized field model uses magnetic tracking and proposes a table-lookup seed calculation (the table comes from measured data.

The tracking data-reduction process includes calculating a seed, which is not always easy.  If the seed algorithm does not work for a particular application, we have a problem.  We can use the previous tracking cycle's result, assuming that the electromagnetic sensor has not moved too far since the last tracking cycle.  This leaves the problem of finding a seed for the initial cycle. Since the seed table must be exhaustively searched, the seed may take a long time to execute.

 

DETAILED DESCRIPTION OF THE INVENTION

C-arm fluoroscope applications (with the electromagnetic sensor mounted on the fluoroscope X-ray detector), the mechanical geometry of the C-arm constrains the movement of the electromagnetic sensor.

This is particularly true if the moving parts of the C-arm contain encoders which report the positions or orientations of the moving parts.

This mechanical information (suitably transformed to tracker coordinates) can be used as the seed in the electromagnetic tracker position-and-orientation calculation.

Similarly, data from ultrasonic, optical, or other tracking systems can be used as a seed for the electromagnetic tracker postion-and-orientation calculation.

These...