GEOFENCE WITH KALMAN FILTER

• US 20130331128A1
• Filed: 03/04/2013
• Published: 12/12/2013
• 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
• Granted Patent: US 9,113,298 B2
• Time in Patent Office: Days
• US Class Current: 455/456.3
• 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 geofencing, comprising:

a Kalman filter module to filter individual location fixes retrieved for a target device;

determining an estimated position of said target device;

determining an estimated heading and velocity of said target device;

establishing a quality estimation from location data retrieved for said target device;

detecting a geofence boundary crossing using said estimated position of said target device; and

establishing a trip profile model for said target device based on historical velocity and heading information relating to said target device.

2. The method of geofencing according to claim 1, further comprising:

dynamically determining time intervals between location fixes for said target device using an estimated velocity of said target device and an estimated heading of said target device.

3. The method of geofencing according to claim 1, further comprising:

detecting a location blunder using said estimated position.

4. The method of geofencing according to claim 1, further comprising:

dynamically determining an appropriate number of location fixes for said target device, to determine said quality estimated position.

5. The method of geofencing according to claim 1, further comprising:

dynamically selecting an energy efficient location technique based on said estimated position, heading and velocity relative to said geofence.