Wireless position location and tracking system

• US 7,602,338 B2
• Filed: 10/27/2007
• Issued: 10/13/2009
• Est. Priority Date: 10/22/2003
• Status: Active Grant

• Current Assignee: Centrak Incorporated (Halma PLC)
• Original Assignee: Awarepoint Corporation
• Inventors: Nierenberg, Nicolas C, Smith, Derek M., Baker, Joseph C., Adams, James D.
• Primary Examiner(s): Issing; Gregory C
• Application Number:
  US11/925,822
• Publication Number:
  US 20080042901A1
• Time in Patent Office: 717 Days
• Field of Search: 342/451
• US Class Current: 342/451
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/02525 Gathering the radio frequency fingerprints
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 4/33 for indoor environments, e.g. buildings
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Techniques for accurate position location and tracking suitable for a wide range of facilities in variable environments are disclosed. In one aspect, a system for position location comprises a plurality of sensors (e.g. a network monitor, an environment sensor) for generating measurements of a plurality of sources, a plurality of objects or tags, each object generating measurements of the plurality of sources, and a processor for receiving the measurements and generating a position location for one or more objects in accordance with the received measurements. In another aspect, a position engine comprises a mapped space of a physical environment, and a processor for updating the mapped space in response to received measurements. The position engine may receive second measurements from an object within the physical environment, and generate a position location estimate for the object from the received second measurements and the mapped space.

Claims

1. An apparatus for locating and tracking at least one mobile object within an indoor facility, the indoor facility including a plurality of beacon emitters positioned therein, a plurality of removable network monitors, and a tag associated with the at least one mobile object, each beacon emitter generating a radiofrequency signal, each network monitors attached to a wall outlet at a known location of the indoor facility and generating a first plurality of measurements comprising data including signal strength from each of the plurality of beacon emitters received by at least one of the removable network monitors, the tag generating a second plurality of measurements comprising data including signal strength from each of the plurality of beacon emitters received by the tag, the apparatus comprising:

a database storing a mapped space of the indoor facility, wherein the mapped space comprises a function and one or more parameters, the function returning a location estimate in response to one or more measurements and the one or more parameters, the parameters being adjusted in response to the first plurality of measurements, wherein the function is selected from a Kalman filter, a Bayesian filter or a neural network;

a memory for storing known location information for each of the plurality of removable network monitors;

a receiver for receiving the first plurality of measurements from one or more network monitors and the second plurality of measurements from the tag associated with the at least one mobile object; and

a processor for updating the mapped space in response to the received first plurality of measurements, the processor updating the mapped space by;

computing a location estimate of a removable network monitor in accordance with the respective first plurality of measurements and the mapped space;

comparing the location estimate with the respective known location information for the removable network monitor to generate a location error estimate; and

adjusting one or more parameters in accordance with the location error estimate,

wherein the processor generates an object position location estimate for the object from the received second plurality of measurements and the mapped space and wherein the processor generates a removable network monitor position location estimate for the plurality of removable network monitors in response to the first plurality of measurements and generates one or more error estimates for the plurality of removable network monitors, each error estimate generated in accordance with a difference between the known location information and generated network monitor position location for the respective removable network monitor.

2. The apparatus of claim 1 wherein the processor repeats the mapped space updating until a location error estimate is less than a pre-determined threshold.

3. The apparatus of claim 1 wherein the mapped space comprises one or more mappings, one of the mappings selected according to an index value, the index value computed in accordance with time, derived from one or more of the first plurality of measurements, computed in accordance with a humidity measurement, or computed in accordance with a temperature measurement.

4. The apparatus of claim 1 wherein the processor generates the mobile object position location estimate further in response to one or more of the error estimates, the one or more error estimates being selected based on the proximity of the respective one or more removable network monitors to the object.

5. The apparatus of 4 wherein the processor produces a weighted average of the one or more error estimates, the weights being selected in accordance with the proximity in signal space of each removable network monitor to the object.

6. A method of locating and tracking at least one object within an indoor facility, the indoor facility including a plurality of beacon emitters positioned therein, a plurality of removable network monitors, and a tag associated with the at least one mobile object, each beacon emitter generating a radiofrequency signal, each removable network monitor removably attached to a wall outlet at a known location of the indoor facility and generating a first plurality of measurements comprising data including signal strength from each of the plurality of beacon emitters received by at least one of the removable network monitors, the tag generating a second plurality of measurements comprising data including signal strength from each of the plurality of beacon emitters received by the tag, the method comprising:

receiving the first plurality of measurements from the plurality of removable network monitors;

receiving the second plurality of measurements from the tag associated with the at least one mobile object;

updating a mapped space in response to the received first plurality of measurements;

storing known location information for each of the plurality of removable network monitors;

computing a location estimate of a removable network monitor in accordance with the received first plurality of measurements and the mapped space;

comparing the location estimate with the respective known location information for the removable network monitor to generate a location error estimate;

adjusting the mapped space in accordance with the location error estimate; and

generating a position location response for the at least one mobile object, determined in accordance with one or more of the second plurality of measurements and the mapped space.

7. The method of claim 6 further comprising:

receiving a position location query for the tag associated with an identified object, wherein the position location response is generated for the identified mobile object;

directing the tag associated with the identified object to update the plurality of second measurements in response to a query;

returning a stored location for the identified object in response to query, wherein the response comprises a set of coordinates, a confidence level, an error estimate, or an area and a confidence level associated with the area.