Navigation system with figure of merit determination

• US 20030023370A1
• Filed: 03/06/2001
• Published: 01/30/2003
• Est. Priority Date: 03/07/2000
• Status: Active Grant

• Current Assignee: Didi (HK) Science and Technology Ltd.
• Original Assignee: Magellan DIS, Inc.
• Inventors: Millington, Jeffrey A., Spencer, Larry E.
• Granted Patent: US 6,741,928 B2
• Time in Patent Office: Days
• US Class Current: 701/209
• CPC Class Codes: G01C 21/3415 Dynamic re-routing, e.g. recalculating the route when the user deviates from calculated route or after detecting real-time traffic data or accidents
• CPC Class Codes: G01C 21/3626 Details of the output of route guidance instructions traffic control systems for road vehicles involving transmission of navigation instructions to the vehicle G08G1/0968
• CPC Class Codes: G01C 21/3667 Display of a road map G01C21/3614 takes precedence; guidance using 3D or perspective road maps G01C21/3635

Abstract

A navigation system switches to a different operational mode based upon a figure of merit determination of the current position solution by the navigation system relative to the map database. If the vehicle navigation system is guiding a driver along a recommended route, and the figure of merit drops below a first predetermined threshold, the navigation system disables an automatic route recalculation routine. If the figure of merit drops below a second predetermined threshold while the vehicle is in route guidance mode, the navigation system displays a textual display of the turn-by-turn instructions along the recommended route to the destination. If the vehicle navigation system is not in a route guidance mode and the figure of merit drops below a third predetermined threshold, the navigation system displays a map of the area surrounding the last current position solution, without displaying the current position of the vehicle.

Claims

1. A method for operating a vehicle navigation system including the steps of:

a) calculating a current position solution;

b) calculating a figure of merit of the current position solution; and

c) changing an operational mode based upon the figure of merit.

2. The method of claim 1 wherein said step c) further includes the step of disabling an automatic route recalculation based upon the figure of merit.

3. The method of claim 2 wherein said step c) further including the step of disabling automatic route recalculation when the figure of merit drops below a predetermined threshold.

4. The method of claim 1 further including the step of calculating a recommended route to a destination.

5. The method of claim 4 further including the step of displaying textual instructions along the recommended route based upon the figure of merit.

6. The method of claim 5 further including the steps of switching from a map display mode to a textual turn-by-turn display mode based upon the figure of merit.

7. The method of claim 1 further including the step of switching from a vehicle heading up display to a north up display based upon the figure of merit.

8. The method of claim 1 further including the step of switching from a map display to a turn-by-turn display based upon the figure of merit.

9. A navigation system comprising:

at least one navigation sensor generating a position signal;

a processor determining a current position based upon the position signal, said processor determining a figure of merit of the current position, said processor changing an operational mode of the navigation system based upon the figure of merit.

10. The navigation system of claim 9 wherein the navigation system changes an output mode based upon the figure of merit.

11. The navigation system of claim 9 further including:

an user input device permitting a user to select a destination;

said processor calculating a recommended route to the destination, said processor including an automatic route recalculation mode in which a new route to the destination is calculated based upon the processor determining that the current position is no longer on the recommended route, said processor disabling said automatic route recalculation based upon said figure of merit.

12. The navigation system of claim 9 further including a display, said display including a plurality of display modes, said navigation system changing said display modes based upon said figure of merit.

13. The navigation system of claim 12 wherein said navigation system switches between a turn-by-turn route guidance mode and a maneuver list mode in which said display displays a textual list of a plurality of maneuvers in the recommended route based upon the figure of merit.

14. The navigation system of claim 11 wherein said display switches between displaying the current position on a map and displaying the map without the current position based upon the figure of merit.

15. A method for operating a vehicle navigation system including the steps of:

a) calculating a current position;

b) determining a confidence level in the current position; and

c) disabling an automatic route recalculation based upon the figure of merit.

16. The method of claim 15 further including the steps of:

selecting a destination and calculating a recommended route to the destination before said step c); and

determining that the current position is not on the recommended route.

17. The method of claim 15 further including the steps of:

selecting a destination and calculating a recommended route to the destination before said step c);

determining that the current position is not on the recommended route before said step c); and

automatically calculating a new recommended route to the destination before said step c).