Method and apparatus for electromagnetic position and orientation tracking with distortion compensation employing a modulated signal

A system for determining the position and orientation of an object or body within a bounded volume containing an AC electromagnetic field distorter, comprising:

• a source of a modulated AC magnetic field having induction-vector components;
• an electronic circuit stabilizing magnitude and phase of the modulated source signal with respect to the internal reference;
• a sensor to measure the induction-vector components at the location of the object or body;
• and
• one or more processors to perform the following functions:
• analyze the induction-vector components of the carrier and satellites to distinguish between source-sensor coupling and source-distorter-sensor coupling, and
• compute the position and orientation of the sensor, and hence, the object or body based on the source-sensor coupling.

In a tracking system of the type wherein source of an AC electromagnetic field having induction-vector components is received by a sensor on an object or body within a bounded volume to determining the position and orientation of the object or body in the presence of a field distorter, the improvement comprising:

• modulating the AC electromagnetic field;
• stabilizing magnitude and phase of the modulated source field components
• analyzing the induction-vector components corresponding to the carrier and modulation frequencies and detected by the sensor to distinguish between source-sensor coupling and source-distorter-sensor coupling;
• and
• computing the position and orientation of the sensor, and hence, the object or body based on the source-sensor coupling.