Method for estimating location of moving object in navigation system

A method for estimating a location of a moving object in a navigation system, comprising:

• (a) receiving GPS (Global Positioning System) location data;
• (b) determining if the moving object has entered a GPS shadow area by using the received GPS location data, said GPS shadow area corresponding to an area where received GPS location data is unreliable;
• (c) obtaining a map-matching value of a last GPS location data in a visible region when the moving object is in a GPS shadow area, and calculating a moving straight distance of the moving object with reference to the map-matching value;
• (d) detecting interpolated points and corresponding links linking the interpolated points using the calculated moving straight distance of the moving object;
• (e) ascertaining which link the moving object is on;
• and
• (f) estimating a moving location by using a length of the link the moving object is on, coordinates of the interpolated points, and a velocity of the moving objects
• wherein the step (c) calculates the moving straight distance based on a non-GPS velocity of the moving object and an estimation unit time period, and
• wherein a next location of the moving object in the shadow area is estimated using the calculated moving straight distance or residue moving straight distance of the moving object, coordinates of interpolated points connecting a corresponding link on the digital numeric map, a length of the corresponding link, and a due north reference angle of the corresponding link.

A method for estimating a location of a moving object in a navigation system, comprising:

• (a) receiving GPS (Global Positioning System) location data;
• (b) determining if the moving object has entered a GPS shadow area by using the received GPS location data, said GPS shadow area corresponding to an area where received GPS location data is unreliable;
• (c) obtaining a map-matching value of a last GPS location data in a visible region when the moving object is in a GPS shadow area, and calculating a moving straight distance of the moving object with reference to the map-matching value;
• (d) detecting interpolated points and corresponding links linking the interpolated points using the calculated moving straight distance of the moving object;
• (e) ascertaining which link the moving object is on;
• and
• (f) estimating a moving location by using a length of the link the moving object is on, coordinates of the interpolated points, and a velocity of the moving object, wherein the step (e) comprises:
• (e-1) calculating a first residue distance of a first link by using a distance to a next interpolated point from the last map-matching value;
• (e-2) comparing the first residue distance of the first link with the calculated moving straight distance, determining that the moving object is on the first link if the first residue distance of the first link is greater than or equal to the calculated moving straight distance, and determining that the moving object is on a second link if the calculated moving straight distance is greater than the first residue distance of the first link;
• and
• (e-3) if the moving object is determined to be on the second link, subtracting a second residue distance of the second link from the calculated moving straight distance, comparing the second residue distance with a distance of a third link, and determining whether the moving object is on the third link.