Determining a location of a mobile device using a multi-modal kalman filter

• US 8,768,618 B1
• Filed: 07/07/2013
• Issued: 07/01/2014
• Est. Priority Date: 05/15/2013
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Williams, Brian Patrick, Kadous, Mohammed Waleed, Christie, David Nicholas
• Primary Examiner(s): Olszewski, John R
• Assistant Examiner(s): McPherson, James M
• Application Number:
  US13/936,202
• Time in Patent Office: 359 Days
• Field of Search: None
• US Class Current: 701/469
• CPC Class Codes: G01S 19/393 Trajectory determination or predictive tracking, e.g. Kalman filtering
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system
• CPC Class Codes: G01S 5/0278 involving statistical or probabilistic considerations G01S5/0252, G01S5/0294 take precedence

Abstract

Methods and systems for determining a location of a mobile device using a multi-modal Kalman filter are described. According to an example method, a mobile device may maintain multiple approximations of a location of a mobile device. Each approximation includes an estimated geographic location of the mobile device that is determined by filtering a respective subset of location estimates received by the mobile device using a respective Kalman filter, and one of the multiple approximations is designated as an active approximation. The method also involves receiving data indicating an estimate of a geographic location of the mobile device and, based on a distance between the estimate of the geographic location and a given approximation of the multiple approximations, updating the given approximation using the estimate of the geographic location. Additionally, the method involves providing for display a visual indication of an estimated geographic location associated with the active approximation.

Claims

1. A method, comprising:

maintaining, by a mobile device, multiple approximations of a location of the mobile device, wherein each approximation comprises an estimated geographic location of the mobile device that is determined by filtering a respective subset of location estimates received by the mobile device using a respective Kalman filter, and wherein one of the multiple approximations is designated as an active approximation;

receiving, by the mobile device, data indicating an estimate of a geographic location of the mobile device;

based on a distance between the estimate of the geographic location and a given approximation of the multiple approximations, updating the given approximation using the estimate of the geographic location; and

providing, by the mobile device and for display, a visual indication of an estimated geographic location associated with the active approximation.

2. The method of claim 1, wherein updating a given approximation of the multiple approximations based on a distance between the estimate of the geographic location and the given approximation comprises:

determining that a closest approximation to the estimate of the geographic location is the given approximation, and

responsive to determining that the closest approximation to the estimate of the geographic location is the given approximation, updating the given approximation.

3. The method of claim 1, further comprising designating the given approximation as the active approximation in response to subsequently receiving a predetermined number of estimates of geographic locations of the mobile device that are closest to the given approximation.

4. The method of claim 1, further comprising:

receiving data indicating a second estimate of a geographic location of the mobile device,

determining that the second estimate of the geographic location of the mobile device is not within a threshold distance of any of the multiple approximations, and

responsive to determining that the second estimate of the geographic location of the mobile device is not within a threshold distance of any of the multiple approximations, maintaining a new approximation based on the second estimate of the geographic location of the mobile device.

5. The method of claim 4, further comprising designating the new approximation as the active approximation in response to subsequently receiving a predetermined number of estimates of geographic locations of the mobile device that are closest to the new approximation.

6. The method of claim 1, further comprising discontinuing a particular approximation of the multiple approximations in response to subsequently receiving a predetermined number of estimates of geographic locations of the mobile device that are not within a threshold distance of the particular approximation.

7. The method of claim 1, further comprising discontinuing a particular approximation of the multiple approximations in response to having a predetermined time period elapse without subsequently receiving any estimates of geographic locations of the mobile device that are within a threshold distance of the particular approximation.

8. The method of claim 1, wherein the estimate of the geographic location of the mobile device is determined using a location-determination component selected from the group consisting of a global positioning system (GPS) and a Wi-Fi component.

9. The method of claim 1, wherein each respective subset is determined based on a respective manner of determining a location.

10. The method of claim 9:

wherein a first one of the multiple approximations comprises a Wi-Fi approximation, the Wi-Fi approximation having an estimated geographic location that is determined based on information collected by scanning for wireless access points within a wireless range of the mobile device, and

wherein a second one of the multiple approximations comprises a global positioning system (GPS) approximation, the GPS approximation having an estimated geographic location that is determined based on GPS data.

11. The method of claim 1, wherein each respective subset is determined based on a distribution of the location estimates such that each respective subset corresponds to a mode of the distribution.

12. A computer-readable medium having stored therein instructions, that when executed by a mobile device, cause the mobile device to perform functions comprising:

maintaining multiple approximations of a location of the mobile device, wherein each approximation comprises an estimated geographic location of the mobile device that is determined by filtering a respective subset of location estimates received by the mobile device using a respective Kalman filter, and wherein one of the multiple approximations is designated as an active approximation;

receiving data indicating an estimate of a geographic location of the mobile device;

based on a distance between the estimate of the geographic location and a given approximation of the multiple approximations, updating the given approximation using the estimate of the geographic location; and

providing for display a visual indication of an estimated geographic location associated with the active approximation.

13. The computer-readable medium of claim 12, wherein updating a given approximation of the multiple approximations based on a distance between the estimate of the geographic location and the given approximation comprises:

determining that a closest approximation to the estimate of the geographic location is the given approximation, and

responsive to determining that the closest approximation to the estimate of the geographic location is the given approximation, updating the given approximation.

14. The computer-readable medium of claim 12, wherein the functions further comprise:

receiving data indicating a second estimate of a geographic location of the mobile device,

determining that the second estimate of the geographic location of the mobile device is not within a threshold distance of any of the multiple approximations, and

responsive to determining that the second estimate of the geographic location of the mobile device is not within a threshold distance of any of the multiple approximations, maintaining a new approximation based on the second estimate of the geographic location of the mobile device.

15. The computer-readable medium of claim 12, wherein the estimate of the geographic location of the mobile device is determined using a location-determination component selected from the group consisting of a global positioning system (GPS) and a Wi-Fi component.

16. The computer-readable medium of claim 12, wherein the functions further comprise discontinuing a particular approximation of the multiple approximations in response to having a predetermined time period elapse without subsequently receiving any estimates of geographic locations of the mobile device that are within a threshold distance of the particular approximation.

17. A mobile device, comprising:

a processor; and

a computer-readable medium, configured to store instructions, that when executed by the processor, cause the mobile device to perform functions comprising;

maintaining multiple approximations of a location of the mobile device, wherein each approximation comprises an estimated geographic location of the mobile device that is determined by filtering a respective subset of location estimates received by the mobile device using a respective Kalman filter, and wherein one of the multiple approximations is designated as an active approximation;

receiving data indicating an estimate of a geographic location of the mobile device;

based on a distance between the estimate of the geographic location and a given approximation of the multiple approximations, updating the given approximation using the estimate of the geographic location; and

providing for display a visual indication of an estimated geographic location associated with the active approximation.

18. The mobile device of claim 17, wherein updating a given approximation of the multiple approximations based on a distance between the estimate of the geographic location and the given approximation comprises:

determining that a closest approximation to the estimate of the geographic location is the given approximation, and

responsive to determining that the closest approximation to the estimate of the geographic location is the given approximation, updating the given approximation.

19. The mobile device of claim 17, wherein the functions further comprise:

receiving data indicating a second estimate of a geographic location of the mobile device,

determining that the second estimate of the geographic location of the mobile device is not within a threshold distance of any of the multiple approximations, and

responsive to determining that the second estimate of the geographic location of the mobile device is not within a threshold distance of any of the multiple approximations, maintaining a new approximation based on the second estimate of the geographic location of the mobile device.

20. The mobile device of claim 17, wherein the estimate of the geographic location of the mobile device is determined using a location-determination component selected from the group consisting of a global positioning system (GPS) and a Wi-Fi component.