Positioning device, method and program with absolute positioning and relative positioning modes

• US 9,134,429 B2
• Filed: 02/21/2012
• Issued: 09/15/2015
• Est. Priority Date: 05/24/2007
• Status: Active Grant

• Current Assignee: TomTom Navigation B.V (TomTom NV)
• Original Assignee: TomTom International BV (TomTom NV)
• Inventors: T'Siobbel, Stephen
• Primary Examiner(s): GALT, CASSI J
• Application Number:
  US13/400,838
• Publication Number:
  US 20120283947A1
• Time in Patent Office: 1,302 Days
• Field of Search: 342/357.28, 342/357.3, 342/357.31, 342/357.32, 342/357.61
• US Class Current: 1/1
• CPC Class Codes: G01C 21/30 Map- or contour-matching
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type

Abstract

The invention relates to a positioning device (PD) arranged to determine a position using an absolute positioning system and a relative positioning system. The positioning device is arranged to work in a first mode, in which the position is determined using the absolute positioning system and possibly the relative positioning system, and in a second mode, in which the position is determined using the relative positioning system and possibly the absolute positioning system. In the first mode the absolute positioning system being weighted more heavily than in the second mode and the positioning device is arranged to switch from the first to the second mode. The positioning device (PD) has access to a digital map database (DMD, 3DMD) and the switch from the first to the second mode is decided based on at least the determined position in combination with information stored in the digital map database (DMD, 3DMD).

Claims

1. A positioning device comprising:

an absolute positioning system and a relative positioning system;

a memory, wherein the memory stores a history file comprising;

a plurality of positions previously determined by the absolute positioning system and an associated accuracy for each of the plurality of determined positions; and

measurements determined by the relative positioning system;

a processor unit, wherein said processor unit is operable to determine a position using the absolute positioning system and the relative positioning system, the positioning device being configured to work in a first mode, in which the position is determined using the absolute position system, and a second mode, in which the position is determined using the relative positioning system in combination with a starting position determined by the absolute positioning system, and the positioning device being configured to switch from the first mode to the second mode, wherein, when a switch is made from the first mode to the second mode, the processor unit is further arranged to check the history file and to select one of the plurality of positions determined by the absolute positioning system as the starting position for the relative positioning system based on the accuracy information stored in the history file.

2. The positioning device according to claim 1, wherein the processor unit is arranged to keep the history file for over a predetermined distance, such that the history file comprises a plurality of positions previously determined by the absolute positioning system over the predetermined distance.

3. The positioning device according to claim 1, wherein the processor unit is arranged to keep the history file for a predetermined time interval, such that the history file comprises a plurality of positions previously determined by the absolute positioning system over the predetermined time interval.

4. The positioning device according to claim 1, wherein the memory further stores a digital map database comprising a plurality of geographical objects, and wherein the processor unit is arranged to keep the history file only if a stored geographical object is being approached that may result in the switch is from the first mode to the second mode.

5. The positioning device according to claim 4, wherein the device is configured to compute if said geographical object is approached based on extrapolation of velocity and direction or based on a planned route.

6. The positioning device according to claim 1, wherein the absolute positioning system is one of a satellite based positioning system and a terrestrial positioning system.

7. The positioning device according to claim 6, wherein the relative positioning system is at least one of a gyroscope, an accelerometer, a compass, a velocity measurement module, a distance meter, an inclinometer and a module to detect steering actions of a steering wheel.

8. The positioning device according to claim 1, wherein the relative positioning system is at least one of a gyroscope, an accelerometer, a compass, a velocity measurement module, a distance meter, an inclinometer and a module to detect steering actions of a steering wheel.

18. The positioning device according to claim 1, wherein the memory further stores a digital map database comprising a plurality of geographical objects having threshold distances associated therewith, and wherein the processor unit is arranged to compute at least one distance from the determined position to a selection of the plurality of geographical objects, and to make the switch from the first mode to the second mode if at least one of the computed distance is below the respective associated threshold.

9. A method for determining a position using a positioning device comprising an absolute positioning system and a relative positioning system, the positioning device being configured to work in a first mode, in which the position is determined using the absolute position system, and a second mode, in which the position is determined using the relative positioning system in combination with a starting position determined by the absolute positioning system, the method comprising:

switching from the first mode to the second mode; and

keeping a history file, the history file comprising;

a plurality of positions previously determined by the absolute positioning system and an associated accuracy for each of the plurality of determined positioned; and

measurements determined by the relative positioning system,

wherein, when the switch is made from the first mode to the second mode, checking the history file and selecting one of the plurality of positions determined by the absolute positioning system as the starting position for the relative positioning system based on the accuracy information stored in the history file.

10. The method according to claim 9, wherein the absolute positioning system is one of a satellite based positioning system and terrestrial positioning system.

11. The method according to claim 10, wherein the absolute positioning system is configured to determine the position based on signals received from a plurality of transmitters being part of the satellite based positioning system or the terrestrial positioning system.

12. The method according to claim 9, wherein the relative positioning system is at least one of a gyroscope, an accelerometer, a compass, a velocity measurement module, a distance meter, a module to detect steering actions of a steering wheel, and an inclinometer.

13. The method according to claim 9, wherein the history file is kept for a predetermined distance, such that the history file comprises a plurality of positions previously determined by the absolute positioning system over the predetermined distance.

14. The method according to claim 9, wherein the history file is kept for a predetermined time interval, such that the history file comprises a plurality of positions previously determined by the absolute positioning system over the predetermined time interval.

15. The method according to claim 9, comprising:

accessing a digital map database comprising a plurality of geographical objects; and

keeping the history file only if a geographical object that may result in a switch from the first mode to the second mode is approached.

16. The method according to claim 15, comprising computing whether said geographical object is approached based on extrapolation of velocity and direction or based on a planned route.

17. A non-transitory computer readable medium comprising program segments which, when executed on a computer device, perform the method of claim 9.

19. The method according to claim 9, comprising:

accessing a digital map database comprising a plurality of geographical objects having threshold distances associated therewith;

computing at least one distance from the determined position to a selection of the plurality of geographical objects; and

switching from the first to the second mode is made if at least one of the computed distances is below the respective associated threshold.