Real-time noise reduction system for dynamic motor frequencies aboard an unmanned aerial vehicle (UAV)

• US 9,489,937 B1
• Filed: 03/09/2015
• Issued: 11/08/2016
• Est. Priority Date: 03/07/2014
• Status: Active Grant

• Current Assignee: Draganfly Innovations Inc. (Frontier Energy Corp.)
• Original Assignee: Trace Live Network Inc.
• Inventors: Clarke, Jamie, Racicot, Erika, Readwin, Paul, Beard, Paul, Chell, Cameron, McDermott, Craig
• Primary Examiner(s): Lao, Lun-See
• Application Number:
  US14/642,496
• Time in Patent Office: 610 Days
• Field of Search: 381/92, 381/1, 381/86, 381 711- 717, 381 7111- 7114, 381 941- 947, 381/26, 181/247, 701/2, 701/3, 244/56, 244/17.23
• US Class Current: 1/1
• CPC Class Codes: B64C 2220/00 Active noise reduction systems
• CPC Class Codes: B64U 10/13 Flying platforms
• CPC Class Codes: B64U 10/14 with four distinct rotor axes, e.g. quadcopters
• CPC Class Codes: B64U 2101/30 for imaging, photography or videography
• CPC Class Codes: G01H 3/00 Measuring characteristics of vibrations by using a detector in a fluid G01H7/00, G01H9/00, G01H11/00 take precedence
• CPC Class Codes: G10K 11/178 by electro-acoustically regenerating the original acoustic waves in anti-phase
• CPC Class Codes: G10K 11/34 using electrical steering of transducer arrays, e.g. beam steering constructional aspects B06B1/0607, B06B1/085
• CPC Class Codes: G10K 2210/1281 Aircraft, e.g. spacecraft, airplane or helicopter
• CPC Class Codes: G10L 2021/02166 Microphone arrays; Beamforming
• CPC Class Codes: G10L 21/0216 characterised by the method used for estimating noise
• CPC Class Codes: G10L 25/48 specially adapted for particular use

Abstract

Systems and methods for simultaneously capturing live audio and video feeds and reducing motor/rotor noise associated with the video feed for a multirotor unmanned aerial vehicle (UAV). Noise reduction occurs in real time or near real time as one or more frequencies associated with a motor, rotor, or attitude of the UAV are recognized, subtracted and/or dithered from the audio feed, resulting in one or more correction signals. The one or more correction signals may be dynamically summed in order to generate a corrected audio feed for transmission.

Claims

1. A system for real-time noise reduction aboard an unmanned aerial vehicle (UAV) having at least one rotor and at least one motor coupled to the at least one rotor, the system comprising:

at least one first microphone fixed to the UAV and configured to capture at least one first audio signal;

at least one sensor fixed to the UAV and configured to determine at least one of a rotor speed of the at least one rotor, a motor speed of the at least one motor, and an attitude of the UAV;

at least one digital signal processor fixed to the UAV and configured to;

determine at least one first frequency corresponding to the at least one rotor, the at least one motor, and the attitude of the UAV;

generate at least one correction signal corresponding to a dynamic sum of the at least one first frequency; and

generate at least one second audio signal by combining the at least one correction signal and the first audio signal.

2. The system of claim 1, wherein the at least one sensor fixed to the UAV includes a second microphone proximal to at least one of the at least one rotor and the at least one motor, the second microphone configured to capture a third audio signal corresponding to at least one of the at least one rotor and the at least one motor, the third audio signal including at least one first frequency.

3. The system of claim 1, wherein the at least one first microphone includes a beamforming array of at least one microphone.

4. The system of claim 1, wherein the at least one digital signal processor is further configured to generate a digital representation of at least one of the first audio signal or the third audio signal.

5. The system of claim 1, further comprising:

at least one clock generator configured to generate at least one time signal defining a bound of a first time window.

6. An unmanned aerial vehicle (UAV) configured to capture a streaming audio feed, comprising:

an airframe;

at least one rotor fixed to the airframe, configured to rotate at a rotor speed selected from a plurality of rotor speeds;

at least one motor coupled to the at least one rotor, configured to drive the at least one rotor and to operate at a motor speed selected from a plurality of motor speeds;

at least one first microphone fixed to the airframe and configured to capture at least one first audio signal;

at least one sensor fixed to the airframe and configured to determine at least one of a rotor speed, a motor speed, and an attitude of the UAV;

at least one digital signal processor coupled to the at least one first microphone and to the at least one sensor, the at least one digital signal processor configured to;

generate a digital representation of the at least one first audio signal;

determine at least one first frequency corresponding to at least one of the rotor speed, the motor speed, and the attitude of the UAV;

generate at least one correction signal corresponding to a dynamic sum of the at least one first frequency; and

generate at least one second audio signal by combining the at least one first audio signal and the at least one correction signal.

7. The unmanned aerial vehicle of claim 6, further comprising:

at least one data storage unit configured to store the at least one second audio signal; and

at least one transmitter configured to transmit the at least one second audio signal via wireless link.

8. The unmanned aerial vehicle of claim 6, further comprising:

at least one camera fixed to the airframe and configured to capture at least one first image corresponding to the at least one first audio signal.

9. The unmanned aerial vehicle of claim 8, wherein the at least one camera and the at least one first microphone are aligned so that the field of vision of the at least one camera corresponds to the coverage area of the at least one first microphone.

10. The unmanned aerial vehicle of claim 6, wherein the at least one first microphone includes a beamforming microphone array.

11. The unmanned aerial vehicle of claim 6, wherein the at least one sensor includes a second microphone proximal to at least one of the at least one rotor and the at least one motor, the second microphone configured to capture a third audio signal corresponding to at least one of a rotor speed and a motor speed, the third audio signal including at least one first frequency.

12. A method for real-time noise reduction aboard an unmanned aerial vehicle (UAV) having (1) at least one rotor and (2) at least one motor coupled to the at least one rotor, the method comprising:

capturing at least one first audio signal via at least one first microphone fixed to the UAV;

determining at least one first frequency corresponding to at least one of the at least one rotor, the at least one motor, and an attitude of the UAV;

generating at least one correction signal corresponding to a dynamic sum of the at least one first frequency;

generating at least one second audio signal by combining the at least one correction signal and the first audio signal.

13. The method of claim 12, wherein determining at least one first frequency corresponding to at least one of the at least one rotor, the at least one motor, and an attitude of the UAV includes

determining at least one of a rotor speed of the at least one rotor, a motor speed of the at least one rotor, and an attitude of the UAV;

and

determining at least one first frequency corresponding to at least one of the rotor speed, the motor speed, and the attitude of the UAV.

14. The method of claim 13, wherein determining at least one of a rotor speed of the at least one rotor, a motor speed of the at least one rotor, and an attitude of the UAV includes

determining at least one of a rotor speed of the at least one rotor, a motor speed of the at least one rotor, and an attitude of the UAV via at least one sensor fixed to the UAV.

15. The method of claim 12, wherein determining at least one first frequency corresponding to at least one of the at least one rotor, the at least one motor, and an attitude of the UAV includes

determining at least one first frequency via at least one sensor coupled to at least one of the at least one rotor and the at least one motor.

16. The method of claim 12, wherein capturing at least one first audio signal via at least one first microphone fixed to the UAV includes

generating at least one time signal, the at least one time signal defining a bound of at least one first time window;

and

capturing at least one first audio signal corresponding to the first time window.

17. The method of claim 16, wherein generating at least one correction signal corresponding to a dynamic sum of the at least one first frequency includes

generating at least one first sum of the at least one first frequency corresponding to the at least one first time window;

and

generating at least one correction signal corresponding to the at least one first sum of the at least one first frequency.

18. The method of claim 17, wherein generating at least one second audio signal by combining the at least one correction signal and the first audio signal includes generating at least one second audio signal corresponding to the at least one first time window by combining the at least one correction signal and the first audio signal corresponding to the at least one first time window.

19. The method of claim 12, wherein:

capturing a first audio signal including at least one first frequency via at least one first microphone fixed to the UAV includes capturing a first audio signal having at least one first frequency and at least one second frequency via at least one first microphone fixed to the UAV; and

generating at least one correction signal corresponding to the dynamic sum of the at least one first frequency includes generating at least one correction signal by subtracting from the first audio signal the at least one first frequency.

20. The method of claim 19, further comprising:

determining whether at least the second frequency corresponds to one or more predetermined frequencies, wherein the predetermined frequencies correspond to one or more desired frequencies, the one or more desired frequencies including at least one or more frequencies associated with human speech;

enhancing the second frequency by adjusting at least one of an electrical resistance, a voltage, or a digital signal associated with the second frequency.

21. The method of claim 12, wherein:

capturing a first audio signal including at least one first frequency via at least one first microphone fixed to the UAV includes capturing a first audio signal having a first amplitude and including at least one first frequency via at least one first microphone fixed to the UAV; and

generating at least one correction signal corresponding to the dynamic sum of the at least one first frequency includes generating at least one correction signal antiphase to the at least one first audio signal and having at least the first amplitude.

22. The method of claim 12, wherein capturing at least one first audio signal including at least one first frequency via at least one first microphone fixed to the UAV includes generating a first digital representation of the at least one first audio signal.