Six-degree of freedom tracking system having a passive transponder on the object being tracked

A system for tracking one or more objects within a region of interest, comprising:

• at least one electromagnetic field generator, fixed with respect to an external frame of reference, each said at least one electromagnetic field generator including a coil, each said at least one electromagnetic field generator being operative to generate a respective excitation field;
• at least one passive transponder, fixed to an object being tracked, wherein an electromagnetic field generated by the electromagnetic field generator causes the transponder to generate electromagnetic signals;
• and
• at least one electromagnetic sensor, fixed with respect to the external frame of reference, which receives electromagnetic signals generated by the transponder and determines the three-dimensional position and three-axis rotational orientation of the object using these signals;
• each said at least one electromagnetic sensor including a coil, each said at least one electromagnetic sensor having a respective response field, said three-dimensional position of the object being determined using linear matrix calculations;
• wherein, for each of said coils:
• if said each coil is included in one of said at least one electromagnetic field generator, said respective excitation field of said one of said at least one electromagnetic field generator is a function of a position, an orientation, and a geometric configuration of said each coil;
• and
• if said each coil is included in one of said at least one electromagnetic sensor, said respective response field of said one of said at least one electromagnetic sensor is a function of a position, an orientation and a geometric configuration of said each coil;
• said coils being substantially planar in shape, arranged in a stack adjacent to the region of interest, and wound so that the amplitudes of signals received by the sensors are substantially independent of the translational position of the object within a plane parallel to said coils.

A system for tracking one or more objects within a region of interest, comprising:

• at least one electromagnetic field generator, fixed with respect to an external frame of reference, each said at least one electromagnetic field generator including a coil;
• at least one passive transponder, fixed to an object being tracked, wherein an electromagnetic field generated by the electromagnetic field generator causes the transponder to generate electromagnetic signals;
• and
• at least one electromagnetic sensor, fixed with respect to the external frame of reference, which receives electromagnetic signals generated by the transponder and determines the three-dimensional position and three-axis rotational orientation of the object using these signals;
• each said at least one electromagnetic sensor including a coil;
• wherein at least one of said coils is spatially extended relative to the region of interest.