Self-correcting adaptive tracking system (SATS)

• US 8,107,395 B2
• Filed: 06/26/2009
• Issued: 01/31/2012
• Est. Priority Date: 06/26/2008
• Status: Active Grant

• Current Assignee: Telcordia Technologies Incorporated (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Telcordia Technologies Incorporated (Telefonaktiebolaget LM Ericsson)
• Inventors: Lau, Richard, Kim, HeeChang, Neidhardt, Arnold L.
• Primary Examiner(s): Phung, Luat
• Application Number:
  US12/492,658
• Publication Number:
  US 20100265836A1
• Time in Patent Office: 949 Days
• Field of Search: 370/252, 370/310, 455/404.2, 455/407, 455/427, 455/456.1, 342/118, 342/147
• US Class Current: 370/252
• CPC Class Codes: G01S 5/0263 by combining or switching between positions derived from two or more separate positioning systems
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 76/50 for emergency connections

Abstract

A system and method for self and group location and tracking based on ultra wide band ranging among members of the group is presented. The system comprises an anchored station, a plurality of nodes, each node having at least knowledge of where the node is facing and heading, knowledge of all pair wise distances among all of the plurality of nodes, and ability to exchange information among the nodes and with the anchored station via relays. The system and method find a new position estimate of the group in accordance with an adaptive search process based on constraints of the ultra wide band ranging, and the search process enables extracting directional information and adaptively stabilizing orientation of the group. In one embodiment, adaptively stabilizing the orientation of the group is performed using an orientation-correcting polygon matching process.

Claims

1. A system for self and group location and tracking based on ultra wide band ranging among members of the group, comprising:

an anchored station;

a plurality of nodes, each node having at least knowledge of where the node is facing and heading, knowledge of all pair wise distances among all of the plurality of nodes, and ability to exchange information among the nodes and with the anchored station; and

one or more relays, wherein a leader node among a plurality of nodes determines placement of the one or more relays by detecting a weak signal from the anchored station and an adaptive search process finds a new position estimate of the group based on constraints of the pair wise distances, enabling extracting of directional information and adaptively stabilizing orientation of the group;

wherein the ability to exchange information comprising inertial measurements and pair wise ranging measurements is performed using WLAN.

2. The system according to claim 1, further comprising both GPS-enabled and GPS-denied partitions.

3. The system according to claim 1, wherein the remote command node initializes the plurality of nodes, assigns one of the nodes as a leader node, runs a graphical user interface in a north-facing mode, and maintains communication with the leader node via WLAN.

4. The system according to claim 1, wherein adaptively stabilizing the orientation of the group is performed using an orientation-correcting polygon matching process.

5. The system according to claim 4, wherein the orientation-correcting polygon matching process comprises steps of:

initializing a first orientation and a second orientation for each node at a first time;

for an orientation-correcting interval, incrementing the first time by one and obtaining polygon matching result, and calculating an error function value for the first orientation and the second orientation at a second time; and

if the error function of the first orientation is greater than the error function of the second orientation, setting a second-interval-first orientation for a second interval to the first orientation less a constant, setting a second-interval-second orientation for the second interval to the second orientation less the constant, otherwise setting the second-interval-first orientation for the second interval to the first orientation plus the constant, setting the second-interval-second orientation for the second interval to the second orientation plus the constant.

6. The system according to claim 4, wherein a flip detection and correction portion of the orientation-correcting polygon matching process comprises steps of:

determining whether the pair wise distance between a first node and a second node of said plurality of nodes has changed;

calculating an expected distance between expected positions of the first node and the second node; and

detecting a flip based on the expected positions of the first and second nodes and the pair wise distance between the first and second nodes.

7. A method for self and group location and tracking based on ultra wide band ranging among members of the group, comprising steps of:

establishing an anchored station;

initializing a plurality of nodes while assigning one of the nodes as a leader node, each node having at least knowledge of where the node is facing and heading, knowledge of all pair wise distances among all of the plurality of nodes, and ability to exchange information among the nodes and with the anchored station;

based on the signal strength from the anchored station, determining placement of one or more relays using the leader node; and

finding a new position estimate of the group in accordance with an adaptive search process based on constraints of the ultra wide band ranging, said search process enabling extracting directional information and adaptively stabilizing orientation of the group;

wherein the ability to exchange information comprising inertial measurements and pair wise ranging measurements is performed using WLAN radio.

8. The method according to claim 7, wherein the anchored station performs steps of

initializing the plurality of nodes;

assigning one of the nodes as a leader node;

running a graphical user interface in a north-facing mode; and

maintaining communication with the leader node via WLAN.

9. The method according to claim 7, wherein adaptively stabilizing the orientation of the group is performed using an orientation-correcting polygon matching process.

10. The method according to claim 9, wherein the orientation-correcting polygon matching process comprises steps of:

initializing a first orientation and a second orientation for each node at a first time;

for an orientation-correcting interval, incrementing the first time by one and obtaining polygon matching result, and calculating an error function value for the first orientation and the second orientation at a second time; and

if the error function of the first orientation is greater than the error function of the second orientation, setting a second-interval-first orientation for a second interval to the first orientation less a constant, setting a second-interval-second orientation for the second interval to the second orientation less the constant, otherwise setting the second-interval-first orientation for the second interval to the first orientation plus the constant, setting the second-interval-second orientation for the second interval to the second orientation plus the constant.

11. The method according to claim 9, wherein a flip detection and correction portion of the orientation-correcting polygon matching comprises steps of:

determining whether the pair wise distance between a first node and a second node of said plurality of nodes has changed;

calculating an expected distance between expected positions of the first node and the second node; and

detecting a flip based on the expected positions of the first and second nodes and the pair wise distance between the first and second nodes.

12. A non-transitory computer readable medium having computer readable program for operating on a computer for self and group location and tracking based on ultra wide band ranging among members of the group, said program comprising instructions that cause the computer to perform the steps of:

establishing an anchored station;

initializing a plurality of nodes, each node having at least knowledge of where the node is facing and heading, knowledge of all pair wise distances among all of the plurality of nodes, and ability to exchange information among the nodes and with the anchored station;

based on the signal strength of the anchored station, determining placement of one or more relays using the leader node; and

finding a new position estimate of the group in accordance with an adaptive search process based on constraints of the ultra wide band ranging, said search process enabling extracting directional information and adaptively stabilizing orientation of the group;

wherein the ability to exchange information comprising inertial measurements and pair wise ranging measurements is performed using WLAN radio.

13. The non-transitory computer readable medium according to claim 12, wherein the anchored station performs steps of:

initializing the plurality of nodes;

assigning one of the nodes as a leader node;

running a graphical user interface in a north-facing mode; and

maintaining communication with the leader node via WLAN.

14. The non-transitory computer readable medium according to claim 12, wherein adaptively stabilizing the orientation of the group is performed using an orientation-correcting polygon matching process.

15. The non-transitory computer readable medium according to claim 14, wherein the orientation-correcting polygon matching process comprises steps of:

initializing a first orientation and a second orientation for each node at a first time;

for an orientation-correcting interval, incrementing the first time by one and obtaining polygon matching result, and calculating an error function value for the first orientation and the second orientation at a second time; and

if the error function of the first orientation is greater than the error function of the second orientation, setting a second-interval-first orientation for a second interval to the first orientation less a constant, setting a second-interval-second orientation for the second interval to the second orientation less the constant, otherwise setting the second-interval-first orientation for the second interval to the first orientation plus the constant, setting the second-interval-second orientation for the second interval to the second orientation plus the constant.

16. The non-transitory computer readable medium according to claim 14, wherein a flip detection and correction portion of the orientation-correcting polygon matching comprises steps of:

determining whether the pair wise distance between a first node and a second node of said plurality of nodes has changed;

calculating an expected distance between expected positions of the first node and the second node; and

detecting a flip based on the expected positions of the first and second nodes and the pair wise distance between the first and second nodes.