Electromagnetic tracking using a discretized numerical field model
First Claim
1. A method for electromagnetic tracking, the method comprising:
- determining a discretized numerical field model associated with a particular distortion source;
acquiring mutual inductance signals between electromagnetic sensors and the particular distortion source, the sensors being rigidly attached to a tracked object;
estimating an initial position for the tracked object in the presence of the particular distortion source;
refining the estimated position of the tracked object; and
estimating an orientation of the tracked object.
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Abstract
A method for electromagnetic tracking the position and orientation of an object using a discretized numerical field model, rather than the conventional analytical dipole model. The method including the steps of determining a discretized numerical field model associated with a particular distortion source; acquiring mutual inductance signals between electromagnetic sensors and the particular distortion source, the sensors being rigidly attached to a tracked object; estimating an initial position for the tracked object in the presence of the particular distortion source; refining the estimated position of the tracked object; and estimating an orientation of the tracked object.
190 Citations
19 Claims
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1. A method for electromagnetic tracking, the method comprising:
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determining a discretized numerical field model associated with a particular distortion source; acquiring mutual inductance signals between electromagnetic sensors and the particular distortion source, the sensors being rigidly attached to a tracked object; estimating an initial position for the tracked object in the presence of the particular distortion source; refining the estimated position of the tracked object; and estimating an orientation of the tracked object. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for electromagnetic tracking, the method comprising:
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determining a discretized numerical field model associated with a particular distortion source; acquiring mutual inductance signals between electromagnetic sensors and the particular distortion source, the sensors being rigidly attached to a tracked object; estimating an initial position for the tracked object in the presence of the particular distortion source; refining the estimated position of the tracked object; and estimating an orientation of the tracked object; wherein the estimating an initial position comprises direct seed-searching and refining results of the direct seed-searching, wherein the direct seed-searching comprises; generating an orientation-independent mutual-inductance squared vector map (“
mapped Lm^2”
) based on acquired mutual inductance measurements associated with the particular distortion source;measuring the acquired mutual inductance signals between the electromagnetic sensors and the particular distortion source; computing mutual-inductance squared vector Lm^2 of the tracked object; determining which hemisphere contains positional (“
x, y, and z”
) components of the Lm^2 of the tracked object;computing the difference from the Lm^2 to each node of the mapped Lm^2; and using, as the direct seed, the node position in the mapped Lm^2 having the smallest Lm^2 difference.
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9. A computer-readable media having computer-executable instructions thereon that, when executed by a computer, perform a method for electromagnetic tracking, the method comprising:
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determining a discretized numerical field model associated with a particular distortion source; acquiring mutual inductance signals between electromagnetic sensors and the particular distortion source, the sensors being rigidly attached to a tracked object; estimating an initial position for the tracked object in the presence of the particular distortion source; refining the estimated position of the tracked object; and estimating an orientation of the tracked object. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for electromagnetic tracking, the method comprising:
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determining a discretized numerical field model associated with a particular distortion source; acquiring mutual inductance signals between electromagnetic sensors and the particular distortion source, the sensors being rigidly attached to a tracked object; measuring a “
distorted”
mutual inductance between the electromagnetic sensors in the presence of the particular distortion source; andcompensating for distortion caused by the particular distortion source by adjusting the measured “
distorted”
position and orientation for the tracked object, wherein the compensation is based upon the acquired discretized numerical field model. - View Dependent Claims (16, 17, 18)
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19. A method for electromagnetic tracking, the method comprising:
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determining a discretized numerical field model associated with a particular distortion source; acquiring mutual inductance signals between electromagnetic sensors and the particular distortion source, the sensors being rigidly attached to a tracked object; measuring a “
distorted”
mutual inductance between the electromagnetic sensors in the presence of the particular distortion source; andcompensating for distortion caused by the particular distortion source by adjusting the measured “
distorted”
position and orientation for the tracked object, wherein the compensation is based upon the acquired discretized numerical field model;wherein the compensating comprises; estimating a initial position for the tracked object in the presence of the particular distortion source; refining the estimated position of the tracked object; and estimating an orientation of the tracked object; wherein the estimating an initial position comprises direct seed-searching and refining results of the direct seed-searching, wherein the direct seed-searching comprises; generating an orientation-independent mutual-inductance squared vector map (“
mapped Lm^2”
) based on acquired mutual inductance measurements associated with the particular distortion source;measuring the acquired mutual inductance signals between the electromagnetic sensors and the particular distortion source; computing mutual-inductance squared vector Lm^2 of the tracked object; determining which hemisphere contains positional (“
x, y, and z”
) components of the Lm^2 of the tracked object;computing the difference from the Lm^2 to each node of the mapped Lm^2; and using, as the direct seed, the node position in the mapped Lm^2 having the smallest Lm^2 difference.
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Specification