Position estimation for navigation devices
First Claim
1. A navigation device, comprising:
- a sensor module operable to provide position estimates based on magnetic field strength measurements;
a processing unit configured to record the magnetic field strength measured by the sensor module of an area substantially surrounding a user of the navigation device, the processing unit further configured to measure a track crossing based on a comparison of a magnetic field strength at a current position and at one or more previous position estimates, and for each measured track crossing, align the current position with the one or more previous position estimates and adjust an accumulation of measurement error below an error threshold based on the one or more previous position estimates; and
wherein the processing unit corrects any intervening positions and error estimates between the current position and the one or more 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.
39 Citations
11 Claims
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1. A navigation device, comprising:
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a sensor module operable to provide position estimates based on magnetic field strength measurements; a processing unit configured to record the magnetic field strength measured by the sensor module of an area substantially surrounding a user of the navigation device, the processing unit further configured to measure a track crossing based on a comparison of a magnetic field strength at a current position and at one or more previous position estimates, and for each measured track crossing, align the current position with the one or more previous position estimates and adjust an accumulation of measurement error below an error threshold based on the one or more previous position estimates; and wherein the processing unit corrects any intervening positions and error estimates between the current position and the one or more previous position estimates. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification