Patent ID: 8207869

Claim:
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.