Techniques for navigating UAVs using ground-based transmitters

• US 9,945,931 B2
• Filed: 12/11/2015
• Issued: 04/17/2018
• Est. Priority Date: 12/12/2014
• Status: Active Grant

• Current Assignee: University of Kansas
• Original Assignee: University of Kansas
• Inventors: Allen, Christopher T., Keshmiri, Shawn Shahriar, Al Aziz, Masud
• Primary Examiner(s): Shaawat, Mussa A
• Assistant Examiner(s): Kerrigan, Michael V
• Application Number:
  US14/966,870
• Publication Number:
  US 20170199269A1
• Time in Patent Office: 858 Days
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Abstract

Systems, methods, apparatuses and computer-readable storage media for navigating an unmanned aerial vehicle (UAV) using signals of opportunity are disclosed. The UAV may include a receiver for detecting a plurality of signals at two or more receiver elements. The UAV may estimate an angle of arrival (AoA) for at least two signals of the plurality of signals, and may estimate a position of the receiver based, at least in part, on the AoA for each of the at least two signals. Known locations of the transmitters that are transmitting the at least two signals may be used in conjunction with the AoAs to determine the estimate of the position of the receiver. More than two signals may be used to localize the estimated position of the receiver.

Claims

1. A method for navigating a vehicle, the method comprising:

detecting, during navigation of a vehicle from a point of origin to a destination, a plurality of signals at two or more receiver elements of a receiver, wherein the receiver is integrated with the vehicle;

estimating, by a processor of the vehicle during the navigation, an angle of arrival (AoA) for at least two signals of the plurality of signals;

estimating, by the processor during the navigation, a current position of the vehicle based, at least in part, on the AoA for each of the at least two signals;

determining, by the processor during the navigation, at least one navigation maneuver for navigating the vehicle from the point of origin to the destination based on the estimated position of the vehicle, wherein the at least one navigation maneuver comprises a steering operation to change a direction of travel of the vehicle, a speed control operation to modify a speed of the vehicle, or a combination thereof; and

executing, by a propulsion and control system of the vehicle, the at least one navigation maneuver.

2. The method of claim 1, wherein the plurality of signals include a plurality of frequency modulation (FM) radio signals, and wherein each of the plurality of FM radio signals is broadcast from one of a plurality of different FM radio transmitters.

3. The method of claim 1, wherein the method includes:

isolating the at least two signals from among the plurality of signals prior to determining the AoA; and

estimating a phase difference of the at least two isolated signals.

4. The method of claim 1, wherein the method includes:

retrieving, from a database stored at a memory of the vehicle, location information associated with at least two transmitters, wherein each of the at least two transmitters transmits a signal of the at least two signals; and

estimating the current position of the vehicle based on the location information and the AoA for each of the at least two signals.

5. The method of claim 1, wherein the current position of the vehicle estimated based on the AoA of the at least two signals is a first location, and wherein the method includes:

determining a global positioning system (GPS) location of the receiver based on GPS signals; and

determining whether the first location corresponds to the GPS location.

6. The method of claim 5, wherein determining whether the first location corresponds to the GPS location includes:

determining a distance between the first location and the GPS location;

determining whether the distance between the first location and the GPS location satisfies a threshold distance; and

modifying a navigation mode of the vehicle from a first navigation mode to a second navigation mode when the distance between the first location and the GPS location does not satisfy the threshold distance, wherein the first navigation mode comprises a GPS assisted navigation mode and the second navigation mode comprises a navigation mode that utilizes position estimates derived from AoAs of received signals for navigation of the vehicle.

7. The method of claim 6, wherein modifying the navigation mode includes initiating operations to navigate the vehicle using only future position estimates of the vehicle determined based on the AoA of the at least two signals.

8. The method of claim 1, wherein the method includes localizing the position of the vehicle using at least one additional signal of the plurality of signals that is different from the at least two signals.

9. The method of claim 1, wherein two or more receiver elements include two or more receive antennas, two or more transducers, or a combination thereof.

10. The method of claim 1, wherein the method further comprises:

determining, by the processor of the vehicle, a number of different frequencies associated with the plurality of signals, each different frequency of the number of different frequencies corresponding to one of the plurality of signals; and

determining whether the number of different frequencies satisfies a threshold number of frequencies, the threshold number of frequencies configured to provide a threshold level of accuracy for estimating the position of the vehicle based on estimates of the AoA for each of the at least two signals,

wherein the at least one navigation maneuver comprises one or more first navigation maneuvers when the number of different frequencies satisfies the threshold number of frequencies, and

wherein the at least one navigation maneuver comprises one or more second navigation maneuvers that are different from the one or more first navigation maneuvers when the number of different frequencies does not satisfy the threshold number of frequencies.

11. The method of claim 1, wherein the method further comprises determining whether the AoA for the at least two signals satisfies range of AoA values configured to provide accurate position estimates for the vehicle, wherein the position of the vehicle is estimated based on AoA estimates that satisfy the range of AoA values.

12. A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, cause the processor to perform operations for navigating a vehicle, the operations comprising:

detecting, during navigation of the vehicle from a point of origin to a destination, a plurality of signals at two or more receiver elements of a receiver, wherein the receiver is integrated with the vehicle;

estimating an angle of arrival (AoA) for at least two signals of the plurality of signals; and

estimating a current position of the vehicle based, at least in part, on the AoA for each of the at least two signals;

determining at least one navigation maneuver for navigating the vehicle from the point of origin to the destination based on the estimated position of the vehicle, wherein the at least one navigation maneuver comprises a steering operation to change a direction of travel of the vehicle, a speed control operation to modify a speed of the vehicle, or a combination thereof; and

controlling a propulsion and control system of the vehicle to execute the at least one navigation maneuver.

13. The non-transitory computer-readable storage medium of claim 12, wherein the plurality of signals include a plurality of frequency modulation (FM) radio signals, and wherein each of the plurality of FM radio signals is broadcast from one of a plurality of different FM radio transmitters.

14. The non-transitory computer-readable storage medium of claim 12, wherein the operations include:

isolating the at least two signals from among the plurality of signals prior to determining the AoA; and

estimating a phase difference of the at least two isolated signals.

15. The non-transitory computer-readable storage medium of claim 12, wherein the operations include:

retrieving, from a database stored at a memory of the vehicle, location information associated with at least two transmitters, wherein each of the at least two transmitters transmits a signal of the at least two signals; and

estimating the position of the vehicle based on the location information.

16. The non-transitory computer-readable storage medium of claim 12, wherein the position of the vehicle estimated based on the AoA of the at least two signals is a first location, and wherein the operations include:

determining a global positioning system (GPS) location of the receiver based on GPS signals; and

determining whether the first location corresponds to the GPS location.

17. The non-transitory computer-readable storage medium of claim 16, wherein the operations for determining whether the first location corresponds to the GPS location further include:

determining a distance between the first location and the GPS location;

determining whether the distance between the first location and the GPS location satisfies a threshold distance; and

modifying a navigation mode of the vehicle from a first navigation mode to a second navigation mode when the distance between the first location and the GPS location does not satisfy the threshold distance, wherein the first navigation mode comprises a GPS assisted navigation mode and the second navigation mode comprises a navigation mode that utilizes position estimates derived from AoAs of received signals for navigation of the vehicle.

18. The non-transitory computer-readable storage medium of claim 17, wherein the operations for modifying the navigation mode of the vehicle include operations for initiating operations to navigate the vehicle using only future position estimates of the vehicle determined based on the AoA of the at least two signals.

19. The non-transitory computer-readable storage medium of claim 12, wherein the operations include determining a differential angle of arrival (dAoA) with respect to two of the at least two signals, wherein the dAoA is configured to remove a reference to an orientation of a geometry of the two or more receiver elements, and wherein the current position of the vehicle is estimated, based at least in part on the dAoA.

20. The non-transitory computer-readable storage medium of claim 12, wherein the operations include localizing the position of the vehicle using at least one additional signal of the plurality of signals that is different from the at least two signals.

21. The non-transitory computer-readable storage medium of claim 12, wherein two or more receiver elements include two or more receive antennas, two or more transducers, or a combination thereof.

22. An unmanned aerial vehicle (UAV) comprising:

a receiver configured to receive a plurality of signals transmitted by a plurality of ground-based transmitters, wherein the plurality of ground-based transmitters includes at least one supertower, and wherein the at least one supertower is configured to transmit two or more signals of the plurality of signals;

a propulsion and control system configured to execute navigation operations for navigating the UAV from a point of origin to a destination; and

a processor configured to;

estimate an angle of arrival (AoA) for signals received from at least two ground-based transmitters of the plurality of ground-based transmitters; and

estimate a current position of the UAV based, at least in part, on the AoA for each of the at least two signals;

determine at least one navigation maneuver for navigating the vehicle from the point of origin to the destination based on the estimated position of the UAV, wherein the at least one navigation maneuver comprises a steering operation to change a direction of travel of the vehicle, a speed control operation to modify a speed of the vehicle, or a combination thereof; and

control execution of the at least one navigation maneuver by the propulsion and control system.

23. The UAV of claim 22, wherein the plurality of signals include a plurality of frequency modulation (FM) radio signals, and wherein each of the plurality of FM radio signals is broadcast from one of the plurality of ground-based transmitters.

24. The UAV of claim 22, wherein the at least one processor is configured to:

isolate the at least two signals from among the plurality of signals prior to determining the AoA; and

estimate a phase difference of the at least two isolated signals, wherein the AoA for each of the signals is determined based on the phase difference.

25. The UAV of claim 22, wherein the at least one processor is configured to:

capture a plurality of snapshots for each of the received signals;

determine a position estimate for the UAV based on each snapshot of the plurality of snapshots using the AoAs; and

average the position estimates to estimate the position of the UAV.

26. The UAV of claim 22, wherein the at least one processor is configured to:

capture a plurality of snapshots for each of the received signals;

determine a phase difference for each snapshot of the plurality of snapshots; and

average the phase differences for each snapshot to determine a final phase difference, wherein the AoAs for each of the signals are estimated based on the final phase difference for each of the plurality of snapshots.

27. The UAV of claim 26, wherein, when the plurality of signals received at the receiver includes signals transmitted by the at least one supertower, the final phase difference for the signals transmitted by the at least one supertower corresponds to an average of the phase differences for all of the signals transmitted by the at least one supertower.

28. The UAV of claim 22, wherein the at least one processor is configured to:

capture a plurality of snapshots for each of the received signals;

determine an AoA for each snapshot of the plurality of snapshots; and

average the AoA for each snapshot to determine a final AoA, wherein the position of the UAV is estimated based on the average AoAs.

29. The UAV of claim 28, wherein, when the plurality of signals received at the receiver includes signals transmitted by the at least one supertower, the final AoA for the signals transmitted by the at least one supertower corresponds to an average of the AoAs for all of the signals transmitted by the at least one supertower.

30. The UAV of claim 22, wherein the position of the UAV estimated based on the AoA of the at least two signals is a first location, and wherein the at least one processor is configured to:

determine a global positioning system (GPS) location of the UAV based on GPS signals;

determine a distance between the first location and the GPS location;

determine whether the distance between the first location and the GPS location satisfies a threshold distance; and

modify a navigation mode of the UAV from a first navigation mode to a second navigation mode when the distance between the first location and the GPS location does not satisfy the threshold distance, wherein the first navigation mode comprises a GPS assisted navigation mode and the second navigation mode comprises a navigation mode that utilizes position estimates derived from AoAs of received signals for navigation of the vehicle.