Event localization within a distributed sensor array

• US 20070247303A1
• Filed: 04/25/2006
• Published: 10/25/2007
• Est. Priority Date: 04/25/2006
• Status: Active Grant

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Payton, David
• Granted Patent: US 7,786,885 B2
• Time in Patent Office: Days
• US Class Current: 340/524
• CPC Class Codes: G01D 21/00 Measuring or testing not otherwise provided for
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04L 67/52 specially adapted for the location of the user terminal
• 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 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

Described is a method for event localization within a distributed sensor array using a plurality of sensor nodes. The method includes an act of receiving a signal in at least one detecting node. The signal originates from an external disturbance and has a local signal such that the local signal reflects a relative proximity (i.e., between the detecting nodes) to the external disturbance. The method also includes acts of exchanging information regarding the signal between the detecting node and nearby nodes; and localizing the external disturbance based on its relative proximity. Through receiving a signal that reflects a relative proximity to the external disturbance and exchanging that information between nearby nodes, the sensor array localizes the external disturbance.

Claims

1. A method for event localization within a distributed sensor array using a plurality of sensor nodes, the method comprising acts of:

receiving a signal in at least one detecting node, the signal originating from an external disturbance and having a local signal at the detecting node such that the local signal reflects the proximity of the detecting node to the external disturbance;

exchanging information regarding the signal between the detecting node and nearby nodes; and

localizing the external disturbance based on its relative proximity to the detecting node, whereby through receiving a signal that reflects a relative proximity of the detecting node to the external disturbance and exchanging that information between nearby nodes, the sensor array localizes the external disturbance.

2. A method as set forth in claim 1, further comprising an act of receiving and measuring the local signal as having a local signal intensity that corresponds to each particular node, such that a local signal having a greater local signal intensity received at a detecting node indicates the node is relatively closer to the external disturbance than a detecting node that receives a local signal that receives a lesser local signal intensity.

3. A method as set forth in claim 2, wherein the act of localizing the external disturbance further comprises an act of:

determining a closest node based on the local signal intensity, such that the detecting node with the relatively largest local signal intensity is assigned to have a maximum signal intensity and is designated as the closest node.

4. A method as set forth in claim 2, wherein the act of localizing the external disturbance further comprises acts of:

determining a successor node value for each node, the successor node value being the local signal intensity of a neighbor node to a selected node that is the next closest to the disturbance after the selected node, with such a neighbor node being designated as the successor node; and

determining the closest n nodes surrounding the external disturbance, thereby allowing the sensor array to localize the external disturbance by determining the closest node and the closest n nodes surrounding the external disturbance.

5. A method as set forth in claim 2, wherein the act of determining the closest node further comprises an act of estimating a relative distance from each node to the disturbance as measured in terms of a hop-count at each node, comprising acts of:

initializing a hop-count variable to zero;

initializing a maximum signal variable to the local signal intensity;

comparing the maximum signal value of each node to the maximum signal values of neighboring nodes;

when the maximum signal value of a neighboring node is greater than the maximum signal value of a selected node;

setting the maximum signal value of the selected node to the maximum signal value of the neighboring node;

setting the hop-count of the selected node so that it is incrementally greater than the hop-count value of the neighboring node;

when the maximum signal value of the neighboring node is less than the maximum signal value of the selected node, then do nothing; and

repeating the act of comparing until the maximum signal value of the neighboring nodes are equal to or less than the maximum signal value of the selected node.

6. A method as set forth in claim 4, wherein the act of determining a successor node value for each node further comprises acts of:

setting a selected node'"'"'s successor node value at an initial value;

determining whether a neighboring node has a local signal intensity less than a selected node'"'"'s local signal intensity;

when the neighboring node has a local signal intensity less than the selected node'"'"'s local signal intensity, then setting a unique identifier for the selected node'"'"'s successor node value such that the identifier identifies the neighboring node;

otherwise, leaving the successor node value for the selected node unchanged;

determining whether another neighboring node'"'"'s local signal intensity is less than the selected node'"'"'s local signal intensity but greater than the selected node'"'"'s current successor node value;

if another neighboring node'"'"'s local signal intensity is less than the selected node'"'"'s local signal intensity but greater than the selected node'"'"'s current successor node value, then setting a unique identifier for the selected node'"'"'s successor node value, such that the unique identifier identifies the other neighboring node; and

otherwise, leaving the selected node'"'"'s successor node value unchanged.

7. A method as set forth in claim 6, wherein the unique identifier for a neighboring node is a representation of that node'"'"'s local signal intensity, such that the act of determining a successor node value for each node comprises acts of:

setting a selected node'"'"'s successor node value at an initial value;

determining if a neighboring node has a local signal intensity lesser than a selected node'"'"'s local signal intensity;

if the neighboring node has a local signal intensity lesser than a selected node'"'"'s local signal intensity, then setting the neighboring node'"'"'s local signal intensity as the selected node'"'"'s successor node value;

otherwise, leaving the successor node value for the selected node unchanged as the neighbor node'"'"'s local signal intensity is not a successor node value for the selected node;

determining whether another neighboring node'"'"'s local signal intensity is greater in signal intensity than the selected node'"'"'s successor node value, but lesser in signal intensity than the selected node'"'"'s local signal intensity;

if another neighboring node'"'"'s local signal intensity is greater in signal intensity than the selected node'"'"'s successor node value, but lesser in signal intensity than the selected node'"'"'s local signal intensity, then setting the another neighboring node'"'"'s local signal intensity as the selected node'"'"'s successor node value; and

otherwise, leaving the selected node'"'"'s successor node value unchanged.

8. A method as set forth in claim 4, wherein the act of determining the closest n nodes further comprises acts of:

determining the successor node value for the closest node;

selecting a successor node, where the local signal intensity of the successor node equals the successor node value;

determining a successor node value for the successor node; and

repeating acts of determining the successor node value for the closest node and selecting a successor node until n nodes have been selected, the nth node being a predetermined number of nodes closest to the external disturbance.

9. A method as set forth in claim 1, wherein the act of localizing the external disturbance further comprises an act of activating a predetermined number of sensor nodes to an active state, such that the predetermined number of nodes are the n nodes closest to the external disturbance as determined by their respective local signal strengths.

10. A method as set forth in claim 1, wherein the act of localizing the external disturbance further comprises an act of activating a predetermined number of sensor nodes to an active state, where only those nodes that are within a predetermined hop-count from the node closest to the disturbance are activated.

11. A method as set forth in claim 1, further comprising acts of:

receiving a second signal at least one detecting node, the second signal originating from a second external disturbance and having a second local signal such that the second local signal reflects a relative proximity of the detecting node to the second external disturbance;

exchanging information regarding the second signal between the detecting node and nearby nodes; and

localizing the second external disturbance based on its relative proximity, whereby by receiving a second signal that reflects a relative proximity to the second external disturbance and exchanging that information between nearby nodes, the sensor array localizes the second external disturbance thereby allowing for triangulation of multiple disturbances.

12. A computer program product for event localization within a distributed sensor array using a plurality of sensor nodes, the computer program product comprising computer-readable instruction means encoded on a computer-readable medium for causing a computer to:

receive a signal in at least one detecting node, the signal originating from an external disturbance and having a local signal at the detecting node such that the local signal reflects the proximity of the detecting node to the external disturbance;

exchange information regarding the signal between the detecting node and nearby nodes; and

localize the external disturbance based on its relative proximity to the detecting node, whereby through receiving a signal that reflects a relative proximity of the detecting node to the external disturbance and exchanging that information between nearby nodes, the sensor array localizes the external disturbance.

13. A computer program product as set forth in claim 12, further comprising instruction means for receiving and measuring the local signal as having a local signal intensity that corresponds to each particular node, such that a local signal having a greater local signal intensity received at a detecting node indicates the node is relatively closer to the external disturbance than a detecting node that receives a local signal that receives a lesser local signal intensity.

14. A computer program product as set forth in claim 13, wherein the instruction means to localize the external disturbance further comprises instruction means for performing an operation of determining a closest node based on the local signal intensity, such that the detecting node with the relatively largest local signal intensity is assigned to have a maximum signal intensity and is designated as the closest node.

15. A computer program product as set forth in claim 13, wherein the instruction means to localize the external disturbance further comprises instruction means for performing operations of:

determining a successor node value for each node, the successor node value being the local signal intensity of a neighbor node to a selected node that is the next closest to the disturbance after the selected node, with such a neighbor node being designated as the successor node; and

determining the closest n nodes surrounding the external disturbance, thereby allowing the sensor array to localize the external disturbance by determining the closest node and the closest n nodes surrounding the external disturbance.

16. A computer program product as set forth in claim 13, wherein the instruction means to determine the closest node further comprises instruction means for performing operations of estimating a relative distance from each node to the disturbance as measured in terms of a hop-count at each node, comprising operations of:

initializing a hop-count variable to zero;

initializing a maximum signal variable to the local signal intensity;

comparing the maximum signal value of each node to the maximum signal values of neighboring nodes;

when the maximum signal value of a neighboring node is greater than the maximum signal value of a selected node;

setting the maximum signal value of the selected node to the maximum signal value of the neighboring node;

setting the hop-count of the selected node so that it is incrementally greater than the hop-count value of the neighboring node;

when the maximum signal value of the neighboring node is less than the maximum signal value of the selected node, then do nothing; and

repeating the act of comparing until the maximum signal value of the neighboring nodes are equal to or less than the maximum signal value of the selected node.

17. A computer program product as set forth in claim 15, wherein the instructions means to determine a successor node value for each node further comprises instruction means for performing operations of:

setting a selected node'"'"'s successor node value at an initial value;

determining whether a neighboring node has a local signal intensity less than a selected node'"'"'s local signal intensity;

when the neighboring node has a local signal intensity less than the selected node'"'"'s local signal intensity, then setting a unique identifier for the selected node'"'"'s successor node value such that the identifier identifies the neighboring node;

otherwise, leaving the successor node value for the selected node unchanged;

determining whether another neighboring node'"'"'s local signal intensity is less than the selected node'"'"'s local signal intensity but greater than the selected node'"'"'s current successor node value;

if another neighboring node'"'"'s local signal intensity is less than the selected node'"'"'s local signal intensity but greater than the selected node'"'"'s current successor node value, then setting a unique identifier for the selected node'"'"'s successor node value, such that the unique identifier identifies the other neighboring node; and

otherwise, leaving the selected node'"'"'s successor node value unchanged.

18. A computer program product as set forth in claim 17, wherein the unique identifier for a neighboring node is a representation of that node'"'"'s local signal intensity, such that the instruction means for determining a successor node value for each node comprises instruction means for performing operations of:

setting a selected node'"'"'s successor node value at an initial value;

determining if a neighboring node has a local signal intensity lesser than a selected node'"'"'s local signal intensity;

if the neighboring node has a local signal intensity lesser than a selected node'"'"'s local signal intensity, then setting the neighboring node'"'"'s local signal intensity as the selected node'"'"'s successor node value;

otherwise, leaving the successor node value for the selected node unchanged as the neighbor node'"'"'s local signal intensity is not a successor node value for the selected node;

determining whether another neighboring node'"'"'s local signal intensity is greater in signal intensity than the selected node'"'"'s successor node value, but lesser in signal intensity than the selected node'"'"'s local signal intensity;

if another neighboring node'"'"'s local signal intensity is greater in signal intensity than the selected node'"'"'s successor node value, but lesser in signal intensity than the selected node'"'"'s local signal intensity, then setting the another neighboring node'"'"'s local signal intensity as the selected node'"'"'s successor node value; and

otherwise, leaving the selected node'"'"'s successor node value unchanged.

19. A computer program product as set forth in claim 15, wherein the instruction means to determine the closest n nodes further comprises instruction means for performing operations of:

determining the successor node value for the closest node;

selecting a successor node, where the local signal intensity of the successor node equals the successor node value;

determining a successor node value for the successor node; and

repeating acts of determining the successor node value for the closest node and selecting a successor node until n nodes have been selected, the nth node being a predetermined number of nodes closest to the external disturbance.

20. A computer program product as set forth in claim 12, wherein the instruction means to localize the external disturbance further comprises instruction means for performing operations of activating a predetermined number of sensor nodes to an active state, such that the predetermined number of nodes are the n nodes closest to the external disturbance as determined by their respective local signal strengths.

21. A computer program product as set forth in claim 12, wherein the instruction means to localize the external disturbance further comprises instruction means for performing operations of activating a predetermined number of sensor nodes to an active state, where only those nodes that are within a predetermined hop-count from the node closest to the disturbance are activated.

22. A computer program product as set forth in claim 12, further comprising instruction means for performing operations of:

receiving a second signal at least one detecting node, the second signal originating from a second external disturbance and having a second local signal such that the second local signal reflects a relative proximity of the detecting node to the second external disturbance;

exchanging information regarding the second signal between the detecting node and nearby nodes; and

localizing the second external disturbance based on its relative proximity, whereby by receiving a second signal that reflects a relative proximity to the second external disturbance and exchanging that information between nearby nodes, the sensor array localizes the second external disturbance thereby allowing for triangulation of multiple disturbances.

23. A system for event localization within a distributed sensor array using a plurality of sensor nodes, the system comprising a plurality of sensor nodes, configured to perform operations of:

receiving a signal in at least one detecting node, the signal originating from an external disturbance and having a local signal at the detecting node such that the local signal reflects the proximity of the detecting node to the external disturbance;

exchanging information regarding the signal between the detecting node and nearby nodes; and

localizing the external disturbance based on its relative proximity to the detecting node, whereby through receiving a signal that reflects a relative proximity of the detecting node to the external disturbance and exchanging that information between nearby nodes, the sensor array localizes the external disturbance.

24. A system as set forth in claim 23, wherein the local signal is received and measured as having a local signal intensity that corresponds to each particular node, such that a local signal having a greater local signal intensity received at a detecting node indicates the node is relatively closer to the external disturbance than a detecting node that receives a local signal that receives a lesser local signal intensity.

25. A system as set forth in claim 24, wherein when localizing the external disturbance, the system is configured to perform an operation of determining a closest node based on the local signal intensity, such that the detecting node with the relatively largest local signal intensity is assigned to have a maximum signal intensity and is designated as the closest node.

26. A system as set forth in claim 24, wherein when localizing the external disturbance, the system is configured to perform operations of:

determining a successor node value for each node, the successor node value being the local signal intensity of a neighbor node to a selected node that is the next closest to the disturbance after the selected node, with such a neighbor node being designated as the successor node; and

determining the closest n nodes surrounding the external disturbance, thereby allowing the sensor array to localize the external disturbance by determining the closest node and the closest n nodes surrounding the external disturbance.

27. A system as set forth in claim 24, wherein when determining the closest node, the system is further configured to perform an operation of estimating a relative distance from each node to the disturbance as measured in terms of a hop-count at each node, comprising operations of:

initializing a hop-count variable to zero;

initializing a maximum signal variable to the local signal intensity;

comparing the maximum signal value of each node to the maximum signal values of neighboring nodes;

when the maximum signal value of a neighboring node is greater than the maximum signal value of a selected node;

setting the maximum signal value of the selected node to the maximum signal value of the neighboring node;

setting the hop-count of the selected node so that it is incrementally greater than the hop-count value of the neighboring node;

when the maximum signal value of the neighboring node is less than the maximum signal value of the selected node, then do nothing; and

repeating the act of comparing until the maximum signal value of the neighboring nodes are equal to or less than the maximum signal value of the selected node.

28. A system as set forth in claim 26, wherein when determining a successor node value for each node, the system is further configured to perform operations of:

setting a selected node'"'"'s successor node value at an initial value;

determining whether a neighboring node has a local signal intensity less than a selected node'"'"'s local signal intensity;

when the neighboring node has a local signal intensity less than the selected node'"'"'s local signal intensity, then setting a unique identifier for the selected node'"'"'s successor node value such that the identifier identifies the neighboring node;

otherwise, leaving the successor node value for the selected node unchanged;

determining whether another neighboring node'"'"'s local signal intensity is less than the selected node'"'"'s local signal intensity but greater than the selected node'"'"'s current successor node value;

if another neighboring node'"'"'s local signal intensity is less than the selected node'"'"'s local signal intensity but greater than the selected node'"'"'s current successor node value, then setting a unique identifier for the selected node'"'"'s successor node value, such that the unique identifier identifies the other neighboring node; and

otherwise, leaving the selected node'"'"'s successor node value unchanged.

29. A system as set forth in claim 28, wherein the unique identifier for a neighboring node is a representation of that node'"'"'s local signal intensity, such that when determining a successor node value for each node, the system is configured to perform the operations of:

setting a selected node'"'"'s successor node value at an initial value;

determining if a neighboring node has a local signal intensity lesser than a selected node'"'"'s local signal intensity;

if the neighboring node has a local signal intensity lesser than a selected node'"'"'s local signal intensity, then setting the neighboring node'"'"'s local signal intensity as the selected node'"'"'s successor node value;

otherwise, leaving the successor node value for the selected node unchanged as the neighbor node'"'"'s local signal intensity is not a successor node value for the selected node;

determining whether another neighboring node'"'"'s local signal intensity is greater in signal intensity than the selected node'"'"'s successor node value, but lesser in signal intensity than the selected node'"'"'s local signal intensity;

if another neighboring node'"'"'s local signal intensity is greater in signal intensity than the selected node'"'"'s successor node value, but lesser in signal intensity than the selected node'"'"'s local signal intensity, then setting the another neighboring node'"'"'s local signal intensity as the selected node'"'"'s successor node value; and

otherwise, leaving the selected node'"'"'s successor node value unchanged.

30. A system as set forth in claim 26, wherein the when determining the closest n nodes, the system is configured to perform operations of:

determining the successor node value for the closest node;

selecting a successor node, where the local signal intensity of the successor node equals the successor node value;

determining a successor node value for the successor node; and

repeating acts of determining the successor node value for the closest node and selecting a successor node until n nodes have been selected, the nth node being a predetermined number of nodes closest to the external disturbance.

31. A system as set forth in claim 23, wherein when localizing the external disturbance, the system is further configured to perform an operation of activating a predetermined number of sensor nodes to an active state, such that the predetermined number of nodes are the n nodes closest to the external disturbance as determined by their respective local signal strengths.

32. A system as set forth in claim 23, wherein when localizing the external disturbance, the system is further configured to perform an operation of activating a predetermined number of sensor nodes to an active state, where only those nodes that are within a predetermined hop-count from the node closest to the disturbance are activated.

33. A system as set forth in claim 23, further configured to perform operations of:

receiving a second signal at least one detecting node, the second signal originating from a second external disturbance and having a second local signal such that the second local signal reflects a relative proximity of the detecting node to the second external disturbance;

exchanging information regarding the second signal between the detecting node and nearby nodes; and

localizing the second external disturbance based on its relative proximity, whereby by receiving a second signal that reflects a relative proximity to the second external disturbance and exchanging that information between nearby nodes, the sensor array localizes the second external disturbance thereby allowing for triangulation of multiple disturbances.