Position estimation for navigation devices
First Claim
1. A method of providing position estimation performed by a processor unit in a navigation device, the method comprising:
- periodically recording magnetic field strength of an area substantially surrounding a navigation device as a user of the navigation device traverses a select pathway;
combining the recorded magnetic field strength with measurements from at least a dead reckoning portion of the navigation device to provide position estimates along the select pathway;
measuring a track crossing based on a comparison of a magnetic field strength at a current position estimate and at one or more previous position estimates;
for each measured track crossing, correlating the current position estimate with the one or more previous position estimates to adjustably align each of the position estimates to within an error threshold based on the one or more previous position estimates; and
correcting each of the position estimates from a starting position on the select pathway, each of the corrected position estimates having an error value below one or more previous position estimates and any intervening positions between each of the one or more previous position estimates and the starting position, the error value corresponding to the error threshold based on the previous position estimates.
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Accused Products
Abstract
A method of providing position estimation with a navigation device comprises periodically recording magnetic field strength of an area substantially surrounding a navigation device as a user of the navigation device traverses a select pathway. The method combines the recorded magnetic field strength with measurements from at least a dead reckoning portion of the navigation device to provide position estimates along the select pathway. The method further corrects each of the position estimates from a starting position on the select pathway, where each of the corrected position estimates have an error value below one or more previous position estimates and any intervening positions between each of the one or more previous position estimates and the starting position, with the error value corresponding to an error threshold based on the previous position estimates.
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Citations
9 Claims
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1. A method of providing position estimation performed by a processor unit in a navigation device, the method comprising:
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periodically recording magnetic field strength of an area substantially surrounding a navigation device as a user of the navigation device traverses a select pathway; combining the recorded magnetic field strength with measurements from at least a dead reckoning portion of the navigation device to provide position estimates along the select pathway; measuring a track crossing based on a comparison of a magnetic field strength at a current position estimate and at one or more previous position estimates; for each measured track crossing, correlating the current position estimate with the one or more previous position estimates to adjustably align each of the position estimates to within an error threshold based on the one or more previous position estimates; and correcting each of the position estimates from a starting position on the select pathway, each of the corrected position estimates having an error value below one or more previous position estimates and any intervening positions between each of the one or more previous position estimates and the starting position, the error value corresponding to the error threshold based on the previous position estimates. - View Dependent Claims (2, 3)
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4. A method of correlating position measurements performed by a processor unit in a navigation device, the method comprising:
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at a first time, continually recording position estimate measurements along a select pathway based on a measured magnetic field strength; on at least a second time of traversing the select pathway, automatically determining a track crossing based on a comparison of a magnetic field strength at a first position estimate and at one or more previous position estimates; and once the track crossing is determined, aligning the track crossing of the first position estimate with the one or more previous position estimates from one or more previous track crossings, the first position estimate adjusted to within a selectable error threshold based on at least one of the previous position estimates and any intervening positions between the at least one previous position estimate and the first position estimate. - View Dependent Claims (5, 6, 7, 8, 9)
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Specification