1. A method comprising:
iteratively fitting data obtained by an underwater sensor from interactions between acoustic signals and an underwater floor; and
deriving at least one of motion, position, or navigation data of the underwater sensor from said fitting.
2. The method of claim 1, further comprising, prior to said iteratively fitting, selecting the data by removing data points near nadir, data points near a data range limit, and data points with weak amplitudes.
3. The method of claim 1, wherein said fitting comprises:
removing data having a deviation higher than a first threshold from a first polynomial;
fitting remaining data to a second polynomial;
reducing the first threshold to a second threshold; and
removing data having a deviation higher than the second threshold from the second polynomial.
4. The method of claim 3, wherein the first and second polynomials are obtained from least-square fitting.
5. The method of claim 3, further comprising repeating said fitting remaining data to a second polynomial until deviations of data, survived from said removing data having a deviation higher than the second threshold from the second polynomial, are within a current threshold.
6. The method of claim 1, wherein said iteratively fitting data comprises iteratively fitting the data obtained from a single discrete transmission of the acoustic signals.
7. The method of claim 1, wherein the data are obtained from multiple discrete transmissions of the acoustic signals, the method further comprising determining whether the data are sufficient for statistics over the multiple discrete transmissions.
8. The method of claim 7, further comprising applying a Bayesian statistics to the data obtained from the multiple discrete transmissions.
9. The method of claim 8, wherein said applying a Bayesian statistics comprises applying a recursive filter.
10. The method of claim 9, wherein said recursive filter comprises a nonlinear Kalman filter.
11. The method of claim 10, wherein the nonlinear Kalman filter comprises an Unscented Kalman Filter.
12. The method of claim 8, further comprising providing at least one of a dynamic model of the motion of the sensor or a dynamic model of the underwater floor variation.
13. The method of claim 1, wherein the derived motion, position, or navigation data comprise:
a first component from the motion of the sensor; and
a second component from the underwater floor variations.
14. The method of claim 13, further comprising separating the first and second components from the data.
15. The method of claim 13, further comprising obtaining the motion data of the sensor from the first component.
16. The method of claim 13, wherein the motion comprises a heave motion, and wherein the second component comprises a multiplicative component introduced by a slope of the underwater floor to the first component, the method further comprising removing the multiplicative component.
17. The method of claim 13, wherein the motion comprises a roll motion, and wherein the second component comprises an additive component introduced by a slope of the underwater floor to the first component, the method further comprising removing the additive component.
18. The method of claim 1, wherein said deriving is performed without a motion or position sensor.
19. The method of claim 1, further comprising:
applying spectrum filtering to the derived motion, position, or navigation data to correct for underwater floor variations.
20. The method of claim 19, wherein said applying spectrum filtering comprises applying a low-pass filter.
21. The method of claim 8, further comprising performing a joint state-parameter estimation over the data to separate a bias in the data introduced by the underwater floor variation.
22. The method of claim 21, further comprising:
dividing a track in the underwater floor into a plurality of segments each having a substantially linear slope; and
estimating the plurality of slopes as a plurality of model parameters in a nonlinear Kalman filter applied to the data.
23. A system comprising:
a transducer array to transmit acoustic signals underwater to interact with an underwater floor; and
a processor to process data obtained from interactions between the acoustic signals and the underwater floor, wherein the processor is configured to:
iteratively fitting data obtained by an underwater sensor from interactions between acoustic signals and an underwater floor; and
deriving at least one of motion, position, or navigation data of the underwater sensor from said fitting.
24. The system of claim 23, wherein the system is a standalone system without a motion or position sensor.
25. A non-transitory computer readable medium having instructions stored thereon, wherein the instructions comprise:
iteratively fitting data obtained by an underwater sensor from interactions between acoustic signals and an underwater floor; and
deriving at least one of motion, position, or navigation data of the underwater sensor from said fitting.
26. The non-transitory computer readable medium of claim 25, wherein said iteratively fitting comprises:
removing data having a deviation higher than a first threshold from a first polynomial;
fitting remaining data to a second polynomial;
reducing the first threshold to a second threshold; and
removing data having a deviation higher than the second threshold from the second polynomial;
repeating said fitting remaining data to a second polynomial until deviations of data, survived from said removing data having a deviation higher than the second threshold from the second polynomial, are within a current threshold.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An apparatus for ablating a layer of tissue having opposed sides comprising:
a first elongated body including a distal end, a proximal end, and a first ablation member, at least a portion of the first body being positioned adjacent one side of the tissue; and
a second elongated body including a distal end, a proximal end, and a second ablation member, at least a portion of the second body being positioned adjacent an opposed side of the tissue, the first and second bodies being positioned in opposed relationship on the opposite sides of the tissue at a selected cardiac location for ablation
at least one of the portions of the first and second bodies having a contoured surface and the other of the first and second bodies having a complementary surface which forms a mating relationship with the contoured surface on opposite sides of the tissue at the selected cardiac location for ablation.
2. The apparatus of claim 1 wherein at least selected one of the first and second bodies includes a source of magnetic force adjacent one side of the tissue and the other of the first and second bodies includes a magnetically attractive element responsive to the magnetic force adjacent the other side of the tissue.
3. The apparatus of claim 1 wherein at least a portion of the first body is positioned on an epicardial surface and at least a portion of the second body is positioned on an endocardial surface.
4. The apparatus of claim 1 further including at least one expandible member disposed on selected one of the first and second bodies.
5. The apparatus of claim 1 further comprising a piercing element which is adapted to extend from the distal end of one of the first and second bodies.
6. The apparatus of claim 1 further comprising a compression sleeve surrounding the first and second bodies which is movable to clamp the layer of tissue between the first and second bodies.
7. A method of ablating a layer of tissue having opposed sides, comprising:
providing a first body including a first ablation member and a source of magnetic force adjacent one side of the tissue, an expandible member located on the first body in the vicinity of the source of magnetic force;
inflating the expandible member to move the source of magnetic force in a direction away from the tissue;
providing a second body including a second ablation member and a magnetically attractive element responsive to the magnetic force adjacent to the other side of the tissue;
deflating the expandible member to move the source of magnetic force in a direction toward the tissue, the magnetic attraction between the source and the attractive element adapted to align the first and second bodies in opposed relationship on the opposed sides of the tissue; and
activating the ablation members at the sides of the tissue layer to ablate the tissue.
8. The method of claim 7 wherein the step of providing a first body includes a second expandible member disposed on the first body in opposed relation to the first named expandible member, and the step of deflating the first named expandible member includes inflating the second expandible member to bias the source of magnetic force adjacent the tissue.
9. The method of claim 7 further including the steps of:
reinflating the first named expandible member to decrease the magnetic attraction between the source of magnetic force of the first body and the magnetically attractive element of the second body to allow repositioning of the second body.
10. The method of claim 9 wherein the step of providing the first body includes a plurality of first bodies, each having an ablation member, a source of magnetic force and an expandible member in the vicinity of the source of magnetic force, each first body being positioned at a different cardiac location selected for ablation adjacent one side of the tissue;
inflating the respective expandible member of the first body to move the respective source of magnetic force in a direction away from the tissue;
positioning the second body adjacent the other side of the tissue in the vicinity of each respective first body;
deflating the respective expandible member of the respective first body; and
repeating the step of activating for each cardiac location.
11. The method of claim 10 wherein the step of providing a first body includes a plurality of bodies which are positioned on an epicardial surface of the heart and the step of providing a second body includes at least one body positioned on an endocardial surface of the heart.
12. The method of claim 11 wherein the step of providing a first body includes approximately six bodies.
13. An apparatus for ablating a layer of tissue having opposed sides comprising:
a first elongated body including a distal end, a proximal end, a first ablation member and a source of magnetic force;
a second elongated body including a distal end, a proximal end, a second ablation member and a magnetically attractive element responsive to the magnetic force, the magnetic attraction between the source and the attractive element adapted to align the first and second bodies in opposed relationship on the opposite sides of the tissue at a selected cardiac location; and
at least one expandible member disposed on selected one of the first and second bodies.
14. The apparatus of claim 13 wherein the expandible member is a balloon.
15. The apparatus of claim 13 wherein a first expandible member is located on the first body and is disposed in the vicinity of the source of magnetic force, the expandible member being inflatable to move the source of magnetic force away from the side of the tissue and being deflatable to move the source of magnetic force toward the side of the tissue.
16. The apparatus of claim 15 wherein a second expandible is located on the first body in opposed relation to the first expandible member, the second expandible member being inflatable to bias the source of magnetic force adjacent the side of tissue.
17. The apparatus of claim 16 wherein each of the first and second expandible members is connected to a inflation lumen which extends proximally to a fluid source located outside a patient’s body.
18. The apparatus of claim 16 wherein each of the first and second expandible members extends from the distal end of the first body to a more proximal location which is in the vicinity of a proximal edge of the source of magnetic source.
19. The apparatus of claim 13 wherein the first body engages an epicardial surface of the heart and the second body engages an endocardial surface of the heart.
20. The apparatus of claim 19 wherein a plurality of first bodies are each positioned at a different location on the epicardial surface of the heart, each first body having an ablation member and a source of magnetic force, the respective sources of magnetic force being magnetically attracted to each other across pericardial reflections of the heart.