Patent ID: 6380732
Filing Date: 2002-04-30
Classification: A61B,F41G,G01B,G01R,G01S

Abstract:
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; 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; and wherein the object is free to move within the region of interest, and there is no physical connection between the object on the one hand and the electromagnetic field generators and electromagnetic sensors on the other hand.