Environmental location system

• US 6,775,616 B1
• Filed: 08/20/2003
• Issued: 08/10/2004
• Est. Priority Date: 02/10/1999
• Status: Expired due to Fees

• Current Assignee: XCI, Inc., X-Cyte Inc.
• Original Assignee: X-Cyte Inc.
• Inventors: Nysen, Paul A.
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US10/646,140
• Time in Patent Office: 356 Days
• Field of Search: 701/200, 701/300, 701/217, 340/988, 340/991, 340/993, 340/995.28, 340/10.1, 340/10.52, 340/825.49, 342/357.09, 342/357.1, 342/357.13, 342/357.14, 342/42, 342/44, 342/46, 342/51
• US Class Current: 701/300
• CPC Class Codes: G01S 13/751 wherein the responder or reflector radiates a coded signal
• CPC Class Codes: G01S 13/876 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S13/874 takes precedence
• CPC Class Codes: G01S 15/874 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S15/872 takes precedence
• CPC Class Codes: G01S 7/40 Means for monitoring or calibrating
• CPC Class Codes: G01S 7/4091 during normal radar operation
• CPC Class Codes: G01S 7/52006 with provision for compensating the effects of temperature
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A system and method for determining a location. The system employs encoded information devices dispersed through the environment, each having a non-unique code associated therewith. The codes from the encoded information devices are acquired as a reading device passes nearby, and stored. The codes from a proximate set of information devices are correlated with a map or mapping relation to determine one or more consistent positions within the environment. The information devices are preferably passive acoustic wave transponders, and the mapping relation may be a pseudorandom sequence or a defined map.

Claims

1. A method of determining a location, comprising:

(a) sensing proximity of a members of a set of landmarks;

(b) storing sequential generic identifications of proximate landmarks, maintaining a sequence of sensing thereof, a single identification being insufficient to determine a location;

(c) searching a database for locations consistent with the stored sequential identifications;

(d) determining a likely location based on the search of the database.

2. The method according to claim 1, further comprising the step of remotely reading an identification from a landmark.

3. The method according to claim 1, further comprising the step of wirelessly reading an identification from a landmark.

4. The method according to claim 1, further comprising the steps of interrogating a landmark and receiving the non-unique identifier from a landmark in response to the interrogation.

5. The method according to claim 1, further comprising the steps of emitting an interrogation signal and receiving, in response to the interrogation signal, the non-unique identifier from a landmark.

6. The method according to claim 1, further comprising the steps of interrogating a landmark with a radio frequency signal, and receiving from the landmark a modified radio frequency signal.

7. The method according to claim 1, further comprising the steps of interrogating a landmark with a radio frequency signal, and receiving from the landmark a backscatter radio frequency signal comprising the identification.

8. The method according to claim 1, wherein said comparing comprises the steps of assuming an initial location, analyzing most recently received landmark identifications and comparing these to predetermined identifiers in a zone around the assumed prior position, and determining at least one consistent position.

9. The method according to claim 8, wherein, if a plurality of locations are consistent, a most likely location is output.

10. The method according to claim 8, wherein, if a plurality of locations are consistent, further landmark identifications are obtained until a unique consistent locations is defined.

11. The method according to claim 1, wherein the sequence of storing sequential generic identifications is statistically processed to increase tolerance to error in reading proximate identifications.

12. The method according to claim 1, wherein each of said landmarks comprises a surface acoustic wave passive backscatter radio frequency identification transponder.

13. The method according to claim 1, wherein at least two landmarks have the same identification.

14. The method according to claim 1, further comprising the step of implementing an error tolerant algorithm for determining a location in the event that one or more errors of the following types occur:

proximity is erroneously sensed and the database is incorrect.

15. The method according to claim 1, wherein said searching comprises computing a correlation of stored sequential generic identifications and relationships with sets of geographically proximate landmark identifications within the database, to determine consistent corresponding locations in a fault tolerant manner.

16. The method according to claim 1, further comprising the steps of determining a landmark location using a secondary positioning system;

and producing a composite location based on the determined likely location and the secondary positioning system.

17. The method according to claim 18, wherein said secondary positioning system comprises a geopositioning signal receiver.

18. The method according to claim 1, wherein the landmarks comprise lane boundary markers of a roadway, wherein the determined likely location is employed to assist in guidance of a vehicle.