System and Method for Real Time Asset Location and Tracking

• US 20100073188A1
• Filed: 09/21/2009
• Published: 03/25/2010
• Est. Priority Date: 09/25/2008
• Status: Active Grant

• Current Assignee: University of Pittsburgh of The Commonwealth System of Higher Education
• Original Assignee: University of Pittsburgh of The Commonwealth System of Higher Education
• Inventors: Rothfuss, Michael A., Hawrylak, Peter J., Mickle, Marlin H.
• Granted Patent: US 8,514,056 B2
• Time in Patent Office: Days
• US Class Current: 340/825.490
• CPC Class Codes: G01S 2205/01 specially adapted for specific applications
• CPC Class Codes: G01S 5/0244 Accuracy or reliability of position solution or of measurements contributing thereto
• CPC Class Codes: G01S 5/0295 Proximity-based methods, e.g. position inferred from reception of particular signals
• CPC Class Codes: G06Q 10/00 Administration; Management

Abstract

A system for estimating the current position of an asset within a location that includes a transponder associated with the asset, a plurality of wireless interface devices provided within the location, and a central computer system in electronic communication with the wireless interface devices. The central computer system is adapted to: (i) identify a particular one or more of the wireless interface devices that have received a wireless signal from the transponder, and (ii) determine an estimate of the current position based on the identified particular one or more of the wireless interface devices.

Claims

1. A method of estimating a current position of a transponder associated with an asset within a location, comprising:

providing a plurality of wireless interface devices within said location;

identifying a particular one or more of said wireless interface devices that have at least received a wireless signal from said transponder; and

determining an estimate of said current position based on the identified particular one or more of said wireless interface devices.

2. The method according to claim 1, wherein said identifying comprises identifying a particular one or more of said wireless interface devices that have received and recognized as valid a wireless signal from said transponder.

3. The method according to claim 1, wherein said identifying and determining steps comprise:

(i) determining a min-term for said transponder, said min-term representing a plurality of Boolean variable values, each of said Boolean variable values being associated with a respective one of said wireless interface devices and indicating whether the one of said wireless interface devices has at least received a wireless signal from said transponder, and (ii) determining the estimate of said current position based on said min-term.

4. The method according to claim 3, wherein said min-term is one of a plurality of possible min-terms, the method further comprising associating each of the possible min-terms with a respective particular position estimate in a look-up table, and wherein said determining the estimate of said current position based on said min-term comprises consulting said look-up table using said min-term.

5. The method according to claim 3, further comprising causing said wireless interface devices to generate a plurality of wireless interrogation signals, wherein said wireless signal from said transponder is generated in response to receipt of at least one of said wireless interrogation signals.

6. The method according to claim 3, wherein said wireless signal from said transponder is generated continuously.

7. The method according to claim 3, wherein said determining a min-term for said transponder comprises selectively adjusting a wireless receiving sensitivity of said wireless interface devices.

8. The method according to claim 7, wherein said determining a min-term for said transponder comprises selectively adjusting the wireless receiving sensitivity of said wireless interface devices to a plurality of levels, determining a particular min-term at each of said levels, and establishing as said min-term the particular min-term determined at a lowest one of said levels.

9. The method according to claim 5, wherein said transponder includes an electronic device having an inactive, sleep state and an active state, wherein said electronic device consumes power from a power source of said transponder in said active state, and wherein the method further comprises, in response to receiving the at least one of said wireless interrogation signals, converting said the at least one of said wireless interrogation signals into at least one DC signal without consuming power from said power source or another power source within or connected to said transponder, and providing a wake-up signal to said electronic device, said wake-up signal causing said electronic device to move from said inactive, sleep state to said active state, wherein thereafter said wireless signal is generated by said transponder.

10. The method according to claim 1, wherein said asset is either an animate object or an inanimate object.

11. The method according to claim 3, wherein each of said Boolean variable values is a 1 if the one of said wireless interface devices associated with the Boolean variable values has received the wireless signal from said transponder and otherwise is a 0.

12. The method according to claim 3, wherein each of said Boolean variable values is a 1 if the one of said wireless interface devices associated with the Boolean variable values has received and recognized as valid the wireless signal from said transponder and otherwise is a 0.

13. A system for estimating a current position of an asset within a location, comprising:

a transponder associated with said asset;

a plurality of wireless interface devices provided within said location; and

a central computer system in electronic communication with said wireless interface devices, said central computer system being adapted to;

(i) identify a particular one or more of said wireless interface devices that have at least received a wireless signal from said transponder, and (ii) determine an estimate of said current position based on the identified particular one or more of said wireless interface devices.

14. The system according to claim 13, wherein said central computer system is adapted to:

(i) identify a particular one or more of said wireless interface devices that have received and recognized as valid a wireless signal from said transponder, and (ii) determine an estimate of said current position based on the identified particular one or more of said wireless interface devices.

15. The system according to claim 13, wherein said central computer system is adapted to perform the identifying and determining by:

(i) determining a min-term for said transponder, said min-term representing a plurality of Boolean variable values, each of said Boolean variable values being associated with a respective one of said wireless interface devices and indicating whether the one of said wireless interface devices has at least received a wireless signal from said transponder, and (ii) determining the estimate of said current position based on said min-term.

16. The system according to claim 15, wherein said min-term is one of a plurality of possible min-terms, wherein said central computer system stores a look-up table that associates each of the possible min-terms with a respective particular position estimate, and wherein said central computer system is adapted to determine the estimate of said current position based on said min-term by consulting said look-up table using said min-term.

17. The system according to claim 15, wherein said central computer system is further adapted to cause said wireless interface devices to generate a plurality of wireless interrogation signals, wherein said wireless signal from said transponder is generated in response to receipt of at least one of said wireless interrogation signals.

18. The system according to claim 15, wherein said wireless signal from said transponder is generated continuously.

19. The system according to claim 15, wherein each of said wireless interface devices has a selectively adjustable wireless receiving sensitivity, and wherein said central computer system is further adapted to determine a min-term for said transponder by performing steps including selectively adjusting the wireless receiving sensitivity of said wireless interface devices.

20. The system according to claim 19, wherein said central computer system is further adapted to determine a min-term for said transponder by selectively adjusting the wireless receiving sensitivity of said wireless interface devices to a plurality of levels, determining a particular min-term at each of said levels, and establishing as said min-term the particular min-term determined at a lowest one of said levels.

21. The system according to claim 13, wherein each of said wireless interface devices has a selectively adjustable wireless receiving sensitivity, and wherein said central computer system is further adapted to identify a particular one or more of said wireless interface devices that have received a wireless signal from said transponder by performing steps including selectively adjusting the wireless receiving sensitivity of said wireless interface devices.

22. The system according to claim 13, wherein said asset is either an animate object or an inanimate object.

23. The system according to claim 15, wherein each of said Boolean variable values is a 1 if the one of said wireless interface devices associated with the Boolean variable values has received the wireless signal from said transponder and otherwise is a 0.

24. The system according to claim 15, wherein each of said Boolean variable values is a 1 if the one of said wireless interface devices associated with the Boolean variable values has received and recognized as valid the wireless signal from said transponder and otherwise is a 0.

25. The system according to claim 13, further comprising a plurality of wireless access points provided within said location, each of said wireless interface devices being in electronic communication with said central computer system through at least one of said wireless access points.

26. The system according to claim 25, wherein wireless access points at least in part implement a wireless network according to the IEEE 802.11 set of standards.

27. The system according to claim 26, wherein said wireless interface devices are adapted to wirelessly communicate with said transponder at a first frequency and with at least one of said wireless access points at a second frequency that is different than said first frequency.

28. The system according to claim 13, wherein each of said wireless interface devices is in electronic communication with said central computer system through a wired connection.

29. The system according to claim 13, wherein each of said wireless interface devices is in electronic communication with said central computer system over existing power lines.

30. The system according to claim 13, wherein said location is one or more buildings.

31. The system according to claim 13, wherein said transponder includes an electronic device having an inactive, sleep state and an active state, wherein said electronic device consumes power from a power source of said transponder in said active state, and wherein in response to receiving the at least one of said wireless interrogation signals, the transponder is structured to convert said the at least one of said wireless interrogation signals into at least one DC signal without consuming power from said power source or another power source within or connected to said transponder, and provide a wake-up signal to said electronic device, said wake-up signal causing said electronic device to move from said inactive, sleep state to said active state, wherein thereafter said wireless signal is generated by said transponder.

32. The system according to claim 13, wherein said location includes a plurality of sub-locations, wherein each of said sub locations includes a set of said wireless interface devices, wherein in each said sub-location a particular one of the set of said wireless interface devices included in the sub-location is structured to determine a sub-min-term for said transponder, the sub-min-term for each sub-location representing a plurality of Boolean variable values, each of said Boolean variable values being associated with a respective one of the wireless interface devices of the set of said wireless interface devices included in the sub-location and indicating whether the one of said wireless interface devices has at least received a wireless signal from said transponder, wherein said central computer system receives one or more of the sub-min-terms and determines said estimate of said current position based on said one or more of the sub-min-terms.

33. The system according to claim 32, wherein said central computer system receives all of the sub-min-terms and determines said estimate of said current position based on all of the sub-min-terms.

34. The system according to claim 32, wherein said central computer system receives less than all of the sub-min-terms and determines said estimate of said current position based on less than all of the sub-min-terms.

35. A method of estimating a current position of a transponder associated with an asset within a location, comprising:

providing a plurality of wireless interface devices within said location, each of said wireless interface devices having a selectively adjustable wireless receiving sensitivity;

setting the wireless receiving sensitivity of each of said wireless interface devices to a starting level;

determining a number of said wireless interface devices that have received a current wireless signal from said transponder;

reducing the wireless receiving sensitivity of each of said wireless interface devices and re-determining the number of said wireless interface devices that have received a then current wireless signal from said transponder one or more times until the number as re-determined is the same as the number just prior to being re-determined;

when the number as re-determined is the same as the number just prior to being re-determined, identifying the particular one or more of said wireless interface devices that have received the then current wireless signal from said transponder; and

determining an estimate of said current position based on the identified particular one or more of said wireless interface devices.

36. A method of estimating a current position of a transponder associated with an asset within a location, comprising:

providing a plurality of wireless interface devices within said location, each of said wireless interface devices having a selectively adjustable wireless receiving sensitivity;

setting the wireless receiving sensitivity of each of said wireless interface devices to a starting level;

determining a min-term for said transponder, said min-term representing a plurality of Boolean variable values, each of said Boolean variable values being associated with a respective one of said wireless interface devices and indicating whether the one of said wireless interface devices has received a current wireless signal from said transponder;

reducing the wireless receiving sensitivity of each of said wireless interface devices and re-determining the min-term for the transponder based on a then current signal from said transponder one or more times until a number of the Boolean variable values in the min-term having a first value does not change; and

when the number of the Boolean variable values in the min-term having a first value does not change, determining an estimate of said current position based on (i) the then current min-term or (ii) the min-term determined immediately prior to the min-term determined just before the then current min-term.

37. A method of estimating a current position of a transponder associated with an asset within a location, comprising:

providing a plurality of wireless interface devices within said location, each of said wireless interface devices having a selectively adjustable wireless receiving sensitivity;

setting the wireless receiving sensitivity of each of said wireless interface devices to a starting level;

determining a number of said wireless interface devices that have received a first wireless signal from said transponder;

if the number of said wireless interface devices that have received the first wireless signal from said transponder is less than or equal to a predetermined amount, identifying the particular one or more of said wireless interface devices that have received the first wireless signal from said transponder and determining an estimate of said current position based on the identified particular one or more of said wireless interface devices that have received the first wireless signal from said transponder; and

if the number of said wireless interface devices that have received the first wireless signal from said transponder is not less than or equal to the predetermined amount, reducing the wireless receiving sensitivity of each of said wireless interface devices and determining a number of said wireless interface devices that have received a then current wireless signal from said transponder one or more times until the number of said wireless interface devices that have received the then current wireless signal from said transponder is less than or equal to the predetermined amount and thereafter identifying the particular one or more of said wireless interface devices that have received the then current wireless signal from said transponder and determining an estimate of said current position based on the identified particular one or more of said wireless interface devices that have received the then current wireless signal from said transponder.

38. A method of estimating a current position of a transponder associated with an asset within a location, comprising:

providing a plurality of wireless interface devices within said location, each of said wireless interface devices having a selectively adjustable wireless receiving sensitivity;

setting the wireless receiving sensitivity of each of said wireless interface devices to a starting level;

determining a first min-term for said transponder, said first min-term representing a plurality of Boolean variable values, each of said Boolean variable values being associated with a respective one of said wireless interface devices and indicating whether the one of said wireless interface devices has received a first wireless signal from said transponder;

determining a number of said wireless interface devices that have received the first wireless signal from said transponder based on the first min-term;

if the number of said wireless interface devices that have received the first wireless signal from said transponder is less than or equal to a predetermined amount, determining an estimate of said current position based on the first min-term;

if the number of said wireless interface devices that have received the first wireless signal from said transponder is not less than or equal to the predetermined amount, reducing the wireless receiving sensitivity of each of said wireless interface devices and determining a then current min-term for the transponder based on a then current signal from said transponder one or more times until it is determined that the number of said wireless interface devices that have received the then current signal from said transponder is less than or equal to a predetermined amount, and thereafter determining an estimate of said current position based on (i) the then current min-term or (ii) the min-term determined immediately prior to the min-term determined just before the then current min-term.

39. An interface device for communicating with both an RF emitting device and a computer system located remotely from said interface device, comprising:

a processing unit;

a wireless communications apparatus operatively coupled to said processing unit, said wireless communications apparatus enabling wireless communications with said RF emitting device and said computer system;

a power interface structured to be coupled to AC power lines for providing primary AC power to said interface device from said AC power lines; and

an energy storage device for providing back-up power to said interface device when said primary AC power from said AC power lines is not available;

wherein said processing unit is programmed to cause said interface device to communicate with said computer system wirelessly using said wireless communications apparatus when said interface device is receiving said primary AC power from said AC power lines, and wherein said processing unit is programmed to cause said interface device to communicate with said computer system over said AC power lines when said primary AC power from said AC power lines is not available.

40. The interface device according to claim 39, wherein said wireless communications apparatus includes a first wireless transceiver for enabling wireless communications with said RF emitting device and a second wireless transceiver for enabling wireless communications with said computer system.

41. The interface device according to claim 39, wherein said energy storage device is a rechargeable battery.

42. The interface device according to claim 39, wherein said an RF emitting device is an RF transponder.

43. A communication system, comprising:

an RF emitting device;

a computer system; and

an interface device located remotely from said computer system, wherein said interface device is operatively coupled to AC power lines for providing primary AC power to said interface device from said AC power lines, wherein said wherein interface device includes an energy storage device for providing back-up power to said interface device when said primary AC power from said AC power lines is not available, wherein said interface device is structured to communicate wirelessly with said RF emitting device, and wherein said interface device is structured to communicate with said computer system wirelessly using when said interface device is receiving said primary AC power from said AC power lines and communicate with said computer system over said AC power lines when said primary AC power from said AC power lines is not available.