PRECISE POSITIONING USING A DISTRIBUTED SENSOR NETWORK

• US 20110156957A1
• Filed: 12/30/2010
• Published: 06/30/2011
• Est. Priority Date: 12/31/2009
• Status: Active Grant

• Current Assignee: Optimal Ranging Inc
• Original Assignee: Optimal Ranging Inc
• Inventors: WAITE, James W., Gargov, Dimitar, Gudmundsson, Thorkell
• Granted Patent: US 9,151,822 B2
• Time in Patent Office: Days
• US Class Current: 342/450
• CPC Class Codes: G01S 5/0205 Details
• CPC Class Codes: G01S 5/02213 Receivers arranged in a network for determining the position of a transmitter
• CPC Class Codes: G01S 5/0226 Transmitters
• CPC Class Codes: G01S 5/0247 Determining attitude
• CPC Class Codes: G01S 5/0252 Radio frequency fingerprinting
• CPC Class Codes: G01V 3/081 the magnetic field is produced by the objects or geological structures characterised by the method of magnetic field measurement G01R33/00

Abstract

A method for determining the location and orientation of a transmitter object by measuring a set of complex electromagnetic field magnitude and phase strengths within a space using one or more receivers is provided. The method includes modeling a set of expected complex electromagnetic strengths to estimated position and orientation of the transmitter object. And estimating parameters related to the transmitter object position based on the residual error between the measured set of complex electromagnetic field values and a set of expected electromagnetic field values. Further embodiments include a method as above including a plurality of receivers with known positions within a limited space including the transmitter object. A sensor network including a plurality of receivers to perform the above method is also provided. The receivers may communicate using a wireless channel.

Claims

1. A method for determining the location and orientation of a transmitter object, the method comprising:

measuring a set of complex electromagnetic field strength magnitude and phase values within a space using one or more receivers;

modeling a set of expected complex electromagnetic strengths at the currently estimated position and orientation of the transmitter object, the set of expected electromagnetic field values corresponding to a model of the transmitter object position in relation to the one or more receivers; and

estimating parameters related to the transmitter object position based on the residual error between the measured set of complex electromagnetic field values and the set of expected electromagnetic field values.

2. The method of claim 1, wherein the parameters related to the object transmitter include:

a position of the object transmitter relative to the one or more receivers;

an off-axis yaw angle of the transmitter object from a reference direction relative to one or more of the dipole transmitters; and

a pitch angle of the transmitter object relative to one or more of the dipole transmitters.

3. The method of claim 1 wherein a physical model is used to track the position and orientation of the transmitter object as it moves through a space.

4. A method for determining the location and orientation of a transmitter object, the method comprising:

providing a plurality of receivers within a limited space comprising the transmitter object;

providing the position of each of the plurality of receivers within a limited space comprising the transmitter;

measuring a set of complex electromagnetic field magnitude and phase strengths with at least one of the plurality of receivers;

modeling a set of expected complex electromagnetic strengths at the currently estimated position and orientation of the transmitter object, the set of expected electromagnetic field values corresponding to a model of the transmitter object position in relation to the position of the one or more receivers; and

estimating parameters related to the transmitter object position based on the residual error between the measured set of complex electromagnetic field values and the set of expected electromagnetic field values.

5. The method of claim 4 wherein the plurality of receivers comprises a 3-axis magnetic dipole receiver.

6. The method of claim 4 wherein the plurality of receivers comprises a dual 3-axis spar receiver.

7. The method of claim 4 further comprising:

providing the estimated parameters related to the transmitter object to a machine in the vicinity of the transmitter object, the machine comprising moving parts, a connection to a GNSS, and a processor to precisely position each part of the machine with respect to the transmitter object.

8. A sensor network comprising a controller and receivers;

the receivers comprising coil detectors to receive RF signals from an RF source;

the coil detectors for each receiver having mutually orthogonal axes; and

further wherein;

the receivers provide information to the controller to locate the source of the RF signals;

the receivers communicate with the controller using a wireless channel and optionally with each other; and

the controller has information of the location of the receivers.

9. The sensor network of claim 8 wherein the controller is configured to track the location of the source of the RF signals, further wherein the source of the RF signals comprises one or more sonde transmitters and one or more linear utility lines, each of the one or more sonde transmitters and the one or more linear utility lines producing an RF signal at a unique frequency.

10. The sensor network of claim 8 wherein a 3-dimensional separation between each of the receivers in the sensor network is determined using an RTK-GPS measurement, with one receiver acting as a GNSS base to all the others in the network.

11. The sensor network of claim 8 wherein each receiver can act as a wireless controller and further wherein:

real-time information available from each receiver in the network includes the offset, depth, range, and orientation of the transmitter object.

12. The sensor network of claim 8 wherein each receiver is connected to a GNSS to more accurately locate a source of the RF signals.

13. The sensor network of claim 8 wherein a synchronization signal between the controller and the plurality of receivers is carried out using a GNSS network.

14. The sensor network of claim 8 wherein a synchronization signal between the controller and the plurality of receivers comprises synchronization beacons provided by the controller.

15. The sensor network of claim 8 wherein the source of the RF signals comprises a transmitter carried by a person traversing a hazard space, and the receivers are carried by one or more persons forming a rescue team.

17. The receiver of claim 14 wherein the other devices in a sensor network comprise a controller that uses the measured RF values and the position provided by the receiver to estimate the location of the RF source.

18. The receiver of claim 14 further comprising a processing unit to compute an estimate of the location of the RF source using the measured RF values, the position provided by the 3-d position measurement unit.

19. The receiver of claim 14 wherein the RF source comprises a plurality of RF transmitters, each transmitter producing an RF signal with a specific code, and the receiver further comprising a processing unit that de-codifies the signal from each of the plurality of RF transmitters.

20. The receiver of claim 14 wherein the 3-d position measurement unit is an RTK-GPS based positioning unit.

16. A receiver to detect RF signals produced by an RF source at a remote location, the receiver comprising:

a structural member having a finite length;

two sets of mutually orthogonal coil detectors, each set placed on either end of the structural member, the coil detectors and the structure forming a local coordinate system;

an orientation sensor to determine the orientation of the local coordinate system relative to an external coordinate system;

a 3-d position measurement unit to determine the position of the local coordinate system relative to one or more points external to the receiver;

a wireless interface to communicate with other devices in a sensor network.