Geofence with kalman filter

• US 9,591,444 B2
• Filed: 02/26/2016
• Issued: 03/07/2017
• Est. Priority Date: 06/12/2012
• Status: Active Grant

• Current Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Original Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Inventors: Qiu, Weigen
• Primary Examiner(s): RAMPURIA, SHARAD K
• Application Number:
  US15/054,437
• Publication Number:
  US 20160183052A1
• Time in Patent Office: 375 Days
• Field of Search: 4554561-457
• US Class Current: 1/1
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 5/0268 by deriving positions from different combinations of signals or of estimated positions in a single positioning system
• CPC Class Codes: G01S 5/0294 Trajectory determination or predictive filtering, e.g. target tracking or Kalman filtering
• CPC Class Codes: H04W 4/021 Services related to particular areas, e.g. point of interest [POI] services, venue services or geofences
• CPC Class Codes: H04W 4/027 using movement velocity, acceleration information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 52/02 Power saving arrangements in wired systems H04L12/12; signaling of mobile application services, e.g. low battery notifications H04W4/20
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A least squares geofence method that minimizes trigger misfires caused by data variability and location blunders and minimizes delayed/missed entry triggers generated under urban or indoor conditions. The least squares geofence method uses a weighted least squares (LS) model to compute a location estimate for a target device. A LS location estimate is used to determine if a target device is located inside or outside a predefined geofence. The present invention additionally comprises a Kalman filter geofence method that further improves the accuracy of entry/exit geofence triggers. A Kalman filter geofence method uses a Kalman filter to filter location data retrieved for a target device. Filtered location data is used to determine if a target device is located inside or outside a predefined geofence. A Kalman filter geofence method estimates velocity and heading information for a target device to generate accurate entry/exit geofence triggers for devices in fast moving mode.

Claims

1. A method of detecting a geofence crossing, comprising:

Kalman filtering a plurality of past individual location fixes retrieved for a wireless device to produce a latest Kalman-filtered location of said wireless device;

determining movement of a target device in a direction away from a geofence boundary;

dynamically determining a more energy efficient location fix before a subsequent Kalman-filtered location of said wireless device, said more energy efficient location fix being determined based on a direction of said wireless device relative to said geofence boundary.

2. The method of detecting a geofence crossing according to claim 1, wherein said more energy efficient location fix comprising:

a cellular network location fix.

3. The method of detecting a geofence crossing according to claim 1, wherein said past individual location fixes comprise:

a global positioning satellite (GPS) location fixes.

4. The method of detecting a geofence crossing according to claim 3, wherein said more energy efficient location fix comprising:

a cellular network location fix.

5. A Kalman filter geofence method, comprising:

obtaining a plurality of locations of a moving target wireless device;

predicting a velocity and heading of said moving target wireless device by filtering said plurality of locations with a Kalman filter module;

triggering a boundary crossing of a moving geofence by said moving target wireless device based on a latest Kalman-filtered location of said moving target wireless device, and said estimated velocity and heading of said moving target wireless device, and based on said moving geofence having a given moving boundary; and

dynamically generating an entry or exit geofence trigger for said target wireless device.

6. The Kalman filter geofence according to claim 5, wherein:

said target wireless device is operating in a fast moving mode.

7. The Kalman filter geofence according to claim 5, further comprising:

detecting a location blunder of said latest Kalman-filtered location of said target wireless device using said latest Kalman-filtered location.

8. The Kalman filter geofence according to claim 5, further comprising:

dynamically determining an appropriate number of individual location fixes retrieved for said target wireless device to produce a subsequent Kalman-filtered location of said target wireless device.

9. The Kalman filter geofence according to claim 5, further comprising:

obtaining a current location of said target wireless device based both on said latest Kalman-filtered location, and on a predicted velocity and heading of said target wireless device relative to said moving given geofence.

10. The Kalman filter geofence according to claim 5, wherein:

said moving geofence is moving differently from movement of said moving target wireless device.

11. The Kalman filter geofence according to claim 5, further comprising:

reducing a time interval between successive location fixes for said target wireless device when said latest Kalman-filtered location is outside said boundary of said moving geofence.

12. The Kalman filter geofence according to claim 5, further comprising:

creating a trip profile for said target wireless device based on a historical measurement of said predicted velocity and heading of said moving target wireless device.

13. A Kalman filter geofence method, comprising:

obtaining a plurality of locations of a moving target wireless device;

predicting a velocity and heading of said moving target wireless device by filtering said plurality of locations with a Kalman filter module;

triggering a boundary crossing of a moving geofence by said moving target wireless device based on a latest Kalman-filtered location of said moving target wireless device, and said estimated velocity and heading of said moving target wireless device, and based on said moving geofence having a given moving boundary; and

dynamically determining an appropriate number of individual location fixes retrieved for said moving target wireless device to produce a subsequent Kalman-filtered location of said moving target wireless device, based on said predicted velocity of said moving target wireless device.

14. The Kalman filter geofence according to claim 13, wherein:

said target wireless device is operating in a fast moving mode.

15. The Kalman filter geofence according to claim 13, further comprising:

detecting a location blunder of said latest Kalman-filtered location of said target wireless device using said latest Kalman-filtered location.

16. The Kalman filter geofence according to claim 13, further comprising:

dynamically determining an appropriate number of individual location fixes retrieved for said target wireless device to produce a subsequent Kalman-filtered location of said target wireless device.

17. The Kalman filter geofence according to claim 13, further comprising:

obtaining a current location of said target wireless device based both on said latest Kalman-filtered location, and on a predicted velocity and heading of said target wireless device relative to said moving given geofence.

18. The Kalman filter geofence according to claim 13, wherein:

said moving geofence is moving differently from movement of said moving target wireless device.

19. The Kalman filter geofence according to claim 13, further comprising:

reducing a time interval between successive location fixes for said target wireless device when said latest Kalman-filtered location is outside said boundary of said moving geofence.

20. The Kalman filter geofence according to claim 13, further comprising:

creating a trip profile for said target wireless device based on a historical measurement of said predicted velocity and heading of said moving target wireless device.