Precise positioning using a distributed sensor network

• US 9,151,822 B2
• Filed: 12/30/2010
• Issued: 10/06/2015
• Est. Priority Date: 12/31/2009
• Status: Active Grant

• Current Assignee: Optimal Ranging Inc
• Original Assignee: Optimal Ranging Inc
• Inventors: Waite, James W., Gudmundsson, Thorkell, Gargov, Dimitar
• Primary Examiner(s): McGue, Frank J
• Application Number:
  US12/982,723
• Publication Number:
  US 20110156957A1
• Time in Patent Office: 1,741 Days
• Field of Search: 342/450
• US Class Current: 1/1
• 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:

distributing a plurality of receivers within a space, each of the plurality of receivers being structurally independent from each other and being positioned within the space in a relation with one another that can change each time the plurality of receivers is distributed, each of the plurality of receivers including one or more antennas and electronics for measuring electromagnetic field strength and phase values from the antennas and wirelessly transmitting data, each of the plurality of receivers being in wireless communication with a controller;

receiving the electromagnetic field strength magnitude and phase values within the space from the plurality of receivers;

modeling a set of expected complex electromagnetic strengths corresponding to a currently estimated position and orientation of the transmitter object relative to each of the plurality of receivers, the set of expected electromagnetic field values corresponding to a model of the transmitter object position in relation to the positions and orientation of each of the plurality of receivers; and

estimating parameters related to the transmitter object position based on a 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 transmitter object include:

a position of the transmitter object relative to the plurality of receivers;

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

a pitch angle of the transmitter object relative to one or more of the plurality of receivers.

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:

distributing a plurality of receivers within a limited space comprising the transmitter object, the plurality of receivers being structurally independent from all others of the plurality of receivers and located within the space in a relation with one another that can change each time the plurality of receivers is distributed, each of the plurality of receivers including one or more antennas and electronics for measuring electromagnetic field strength and phase values from the antennas and wirelessly transmitting data, each of the plurality of receivers being in wireless communication with a controller;

determining receiver position data, the receiver position data indicating the position and orientation of each of the plurality of receivers within the limited space comprising the transmitter object;

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 a 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 and orientation of the at least one of the plurality of receivers; and

estimating parameters related to the transmitter object position based on a 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 each of the plurality of receivers comprises a 3-axis magnetic dipole receiver.

6. The method of claim 4 wherein each of 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 and the plurality of receivers, 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, the machine capable of performing work.

8. A sensor network comprising a controller and a plurality of receivers;

the receivers each comprising one or more coil detectors to receive RF signals from an RF source;

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

further wherein;

the plurality of receivers are structurally independent and distributable within a space in a relation with one another that can change each time the plurality of receivers is distributed, each of the plurality of receivers including electronics for measuring electromagnetic field strength and phase values from the one or more coil detectors and a transmitter for wirelessly transmitting data,

the plurality of receivers provide information to the controller to locate the source of the RF signals, the information including position and orientation information of each of the plurality of receivers; and

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

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 a known RF signal.

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 an 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.

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

a set of mutually orthogonal coil detectors, the coil detectors 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; and

a two-way wireless interface to communicate with other devices in a sensor network formed by the receiver, at least one other structurally independent receiver, and a controller, the controller being structurally detached from the receiver, wherein the receiver and the at least one other structurally independent receiver are distributable within a space of the RF source that can be different each time the receiver and the at least one other structurally independent receiver are distributed.

17. The receiver of claim 16 wherein the controller is configured to use the measured RF values and the position provided by the receiver to estimate the location of the RF source.

18. The receiver of claim 16 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 16 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 16 wherein the 3-d position measurement unit is an RTK-GPS based positioning unit.