Method and system for navigating a catheter probe in the presence of field-influencing objects

A correction system for determining an effect of a field influencing shield device on a field sensor in a navigational domain, said correction system comprising:

• a transmitter configured to project into said navigational domain field energy sufficient to induce a signal value in said field sensor;
• a storage device containing information corresponding to said field energy in said navigational domain at selected locations within said navigational domain, said information including shield information incorporating the effect of said field influencing shield device at said selected locations;
• and,
• a processor for accessing said storage device and said signal value to determine the effect of said shield device on said field sensor, to thereby permit a substantially precise location of said field sensor to be determined despite the presence of said field influencing shield device.

A method of determining a substantially precise location of a field sensor within a navigational domain influenced by at least one field interfering object, the method comprising:

• inducing within said field sensor a first signal value at a first waveform having a first frequency, the first signal value being influenced by said at least one field interfering object;
• inducing within said field sensor a second signal value at a second waveform having a second frequency, the second signal value being influenced by said at least one field interfering object;
• and,
• determining an effect of said field interfering object by determining an eddy current produced in said at least one field interfering object.

A method of determining a substantially precise location of a first field sensor within a navigational domain influenced by at least one field interfering object, the method comprising:

• inducing within said first field sensor a first signal value, the first signal value being influenced by said field interfering object;
• inducing within a second field sensor a second signal value, the second signal value being influenced by said field interfering object;
• and,
• determining an effect of said field interfering object by determining an eddy current produced in said at least one field interfering object.

A method of determining a substantially precise location of a field sensor within a navigational domain influenced by a field influencing shield device, the method comprising:

• inducing within said field sensor a first signal value, the first signal value being influenced by said field influencing shield device;
• accessing information from a storage device, said information including shield information incorporating the effect of said field influencing shield device at selected locations;
• and
• determining a correction to said first signal value for the effects of said field influencing shield device.

A method of determining a substantially precise location of a field sensor within a navigational domain influenced by a field interfering object, the method comprising:

• sequentially projecting into said navigational domain, via three unidirectional coils and six delta coils, navigational energy at a first frequency, and measuring a first signal value in said field sensor corresponding to each of said three unidirectional coils and said six delta coils, so as to produce nine of said first signal values;
• sequentially projecting into said navigational domain, via three unidirectional coils and six delta coils, and said navigational energy at a second frequency, and measuring a second signal value in said field sensor corresponding to each of said three unidirectional coils and said six delta coils, so as to produce nine of said second signal values;
• calculating, for each of said unidirectional and delta coils, an adjusted signal value as a predetermined function of said first signal value and said second signal value, so as to produce nine adjusted signal values, each corresponding to navigational magnetic energy from one of said unidirectional coils and delta coils;
• forming three independent equations including (i) three adjusted signal values corresponding to said unidirectional coils, (ii) three predetermined field magnitude values due to each of said unidirectional coils and corresponding to said navigational energy at a last navigational point of said field sensor, and (iii) unknown orientation variables, and simultaneously solving said independent equations to determine said orientation variables corresponding to said compensated orientation of said field sensor;
• generating three lines and determining an intersection of said three lines, said intersection corresponding to said compensated position of said field sensor, wherein each of said lines is generated from (i) adjusted signal values corresponding to a pair of said delta coils, and (ii) predetermined field magnitude values due to said pair of delta coils and corresponding to said navigational energy at said last navigational point of said field sensor while oriented according to said compensated orientation.

A method of determining a substantially precise location of a first field sensor within a navigational domain influenced by a field interfering object, the method comprising:

• sequentially projecting into said navigational domain, via three unidirectional coils and six delta coils, a navigational energy at a first frequency, measuring a first signal value in said first field sensor corresponding to each of said three unidirectional coils and said six delta coils, so as to produce nine of said first signal values, and measuring a second signal value in a second field sensor corresponding to each of said three unidirectional coils and said six delta coils, so as to produce nine of said second signal values;
• calculating, for each of said unidirectional and delta coils, an adjusted signal value as a predetermined function of said first signal value and said second signal value, so as to produce nine adjusted signal values, each corresponding to navigational magnetic energy from one of said unidirectional coils and delta coils;
• forming three independent equations including (i) three adjusted signal values corresponding to said unidirectional coils, (ii) three predetermined field magnitude values due to each of said unidirectional coils and corresponding to said navigational energy at a last navigational point of said first field sensor, and (iii) unknown orientation variables, and simultaneously solving said independent equations to determine said orientation variables corresponding to said compensated orientation of said first field sensor;
• generating three lines and determining an intersection of said three lines, said intersection corresponding to said compensated position of said first field sensor, wherein each of said lines is generated from (i) adjusted signal values corresponding to a pair of said delta coils, and (ii) predetermined field magnitude values due to said pair of delta coils and corresponding to said navigational energy at said last navigational point of said first field sensor while oriented according to said compensated orientation.

A method of determining a substantially precise location of a first field sensor within a navigational domain influenced by a field influencing shield device, the method comprising:

• sequentially projecting into said navigational domain, via three unidirectional coils and six delta coils, a navigational energy at a first frequency, measuring a first signal value in said field sensor corresponding to each of said three unidirectional coils and said six delta coils, so as to produce nine of said first signal values;
• forming three independent equations including (i) three adjusted signal values corresponding to said unidirectional coils, (ii) three predetermined field magnitude values due to fields from each of said unidirectional coils and corresponding to said navigational energy at a last navigational point of said field sensor, said predetermined field magnitude values being manipulated so as to account for said shield device, and (iii) unknown orientation variables, and simultaneously solving said independent equations to determine said orientation variables corresponding to said compensated orientation of said sensing coil;
• generating three lines and determining an intersection of said three lines, said intersection corresponding to said compensated position of said sensing coil, wherein each of said lines is generated from (i) adjusted signal values corresponding to a pair of said delta coils, and (ii) predetermined field magnitude values due to said pair of delta coils and corresponding to said navigational energy at said last navigational point of said sensing coil while oriented according to said compensated orientation, said predetermined field magnitude values being manipulated so as to account for said effect of the shield device.