Multirotor mobile buoy for persistent surface and underwater exploration

• US 9,457,900 B1
• Filed: 03/18/2016
• Issued: 10/04/2016
• Est. Priority Date: 04/07/2014
• Status: Active Grant

• Current Assignee: The Government Of The United States As Represented By The Secretary Of The Navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Dobrokhodov, Vladmir N., Jones, Kevin D.
• Primary Examiner(s): Davis, Richard G
• Application Number:
  US15/073,831
• Time in Patent Office: 200 Days
• Field of Search: 440/6, 441/6, 441/21
• US Class Current: 1/1
• CPC Class Codes: B63B 22/00 Buoys floating decoys, e.g. for waterfowl A01M31/06; means for indicating the location of underwater objects B63C7/26; life-buoys, e.g. rings B63C9/08; mountings of acoustic transducer in underwater equipment, e.g. sonobuoys G10K11/006; electric cables supported on or from floats H02G9/12
• CPC Class Codes: B64C 25/54 Floats
• CPC Class Codes: B64C 27/08 with two or more rotors
• CPC Class Codes: B64C 37/00 Convertible aircraft
• CPC Class Codes: B64C 39/02 characterised by special use
• CPC Class Codes: B64C 39/022 Tethered aircraft
• CPC Class Codes: B64C 39/024 of the remote controlled vehicle type, i.e. RPV
• CPC Class Codes: B64U 10/10 Rotorcrafts
• 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 2101/00 UAVs specially adapted for particular uses or applications
• CPC Class Codes: B64U 2101/20 for use as communications relays, e.g. high-altitude platforms
• CPC Class Codes: B64U 2201/102 adapted for flying in formations
• CPC Class Codes: B64U 2201/104 using satellite radio beacon positioning systems, e.g. GPS
• CPC Class Codes: B64U 30/20 Rotors; Rotor supports
• CPC Class Codes: B64U 50/19 using electrically powered motors
• CPC Class Codes: B64U 50/31 generated by photovoltaics
• CPC Class Codes: B64U 50/34 In-flight charging photovoltaics B64U50/31
• CPC Class Codes: B64U 70/00 Launching, take-off or landing arrangements

Abstract

A multirotor mobile buoy combining MR-VTOL capability with environmentally hardened electronics, exchangeable sensor suites, and a solar recharge system and providing sensing in aquatic environments. The multirotor mobile buoy provides for the detection, classification and location of underwater objects using self-contained electronics, and repositions with aerial means using a plurality of rotors. The multirotor mobile buoy additionally incorporates solar panels for recharging of on-board batteries enabling the flight and other functions, and comprises a buoyant assembly and extended tether in order to promote stability in dynamic, open ocean environments. The multirotor mobile buoy may be employed singly or as a swarm of underwater detection platforms, and may utilize its positioning ability to optimize the effectiveness of sonobuoy systems arrayed as a distributed sensor field.

Claims

1. A multirotor mobile buoy for surface and underwater reconnaissance comprising:

a central frame comprising,

a central housing,

a plurality of frame support members where each frame support member extends from the central housing and,

a plurality of rotor support members where each rotor support member is coupled to the central housing, at least one of the frame support members comprising the plurality of frame support members, or a combination thereof;

a buoyant assembly coupled to the central frame where the buoyant assembly is configured to float on water;

a plurality of rotors where each rotor comprises a motor, a rotating mast coupled to the motor, a hub coupled to the rotating mast, and a plurality of rotor blades coupled to the hub, and where the each rotor is coupled to at least one rotor support member in the plurality of rotor support members, where the at least one rotor support member is coupled to the central housing, the at least one of the frame support members, or a combination thereof and where the buoyant assembly is coupled to the central frame such that the rotating mast, the hub, and the plurality of rotor blades of the each rotor is above the water when the buoyant assembly floats on water and such that the plurality of rotor blades of the each rotor is oriented to direct a thrust in a direction toward a surface of the water when the buoyant assembly floats on water;

a plurality of solar cells where each solar cell comprises a sun-facing side, where the each solar cell is coupled to at least one frame support member in the plurality of frame support members where the at least one frame support member is coupled to the central housing and the buoyant assembly is coupled to the central frame such that the sun-facing side of the each solar cell is above the water when the buoyant assembly floats on water;

a battery electrically connected to the each solar cell and electrically connected to each motor in the plurality of rotors; and

a tether coupled to the central housing at a first end and coupled to a sensor configured to detect underwater objects at a second end, where the sensor is configured to sink in water and where the tether is coupled to the central housing at the first end and coupled to the sensor at the second end such that the second end of the tether is submerged in the water when the buoyant assembly floats on water.

2. The multirotor mobile buoy of claim 1 where the where central housing has a vertical axis extending through the central housing when the buoyant assembly floats on water, and where the buoyant assembly generates one or more buoyant forces when the buoyant assembly floats on water, where each of the buoyant forces is parallel to the vertical axis, and where each plurality of rotor blades in each rotor in the plurality of rotors has a plane of rotation, and the plane of rotation is substantially perpendicular to the vertical axis.

3. The multirotor mobile buoy of claim 2 where the buoyant assembly is coupled to the plurality of frame support members.

4. The multirotor mobile buoy of claim 3 where the buoyant assembly is a plurality of pontoons and where the apparatus has a total combined weight, and where each pontoon has a displacement volume, and where a weight of water having a volume equal to the displacement volume is greater than the total combined weight of the apparatus.

5. The multirotor mobile buoy of claim 4 where the each pontoon in the plurality of pontoons is coupled to at least one frame support member in the plurality of frame support members.

6. The multirotor mobile buoy of claim 2 where a reference diameter D is perpendicular to the vertical axis and surrounds the central frame and the buoyant assembly, and where the tether has a length L from the central housing to the sensor, and where the length L is at least 10 times greater than the reference diameter D.

7. The multirotor mobile buoy of claim 6 where the sensor has a mass M and the multirotor mobile buoy has a center of gravity and a center of buoyancy when the buoyant assembly floats on water, and where the center of gravity is below the center of buoyancy when the buoyant assembly floats on water and the tether has the length L and the mass M.

8. The multirotor mobile buoy of claim 2 further comprising a computing system within the central housing where the computing system is configured to receive data from the sensor.

9. The multirotor mobile buoy of claim 8 where the computing system is configured to receive data from the sensor via a communication cable where the communication cable extends from the computing system to the sensor.

10. The multirotor mobile buoy of claim 9 further comprising an onboard global positioning system and inertial navigation system (GPS/INS) configured to determine a location of the apparatus and where the computing system is configured to receive location information from the GPS/INS and control the location of the apparatus using the plurality of rotors.

11. The multirotor mobile buoy of claim 8 where the apparatus comprises an antenna and where the computing system is further configured to communicate with external systems using the antenna.

15. The multirotor mobile buoy of claim 9 further comprising an onboard global positioning system and inertial navigation system (GPS/INS) configured to determine a location of the apparatus and where the computing system is configured to receive location information from the GPS/INS and control the location of the apparatus using the plurality of rotors.

12. A multirotor mobile buoy for surface and underwater reconnaissance comprising:

a central frame comprising,

a central housing,

a plurality of frame support members where each frame support member extends from the central housing and,

a plurality of rotor support members where each rotor support member is coupled to the central housing, at least one of the frame support members comprising the plurality of frame support members, or a combination thereof;

a buoyant assembly coupled to the central frame where the buoyant assembly is configured to float on water;

a plurality of rotors where each rotor comprises a motor, a rotating mast coupled to the motor, a hub coupled to the rotating mast, and a plurality of rotor blades coupled to the hub, and where the each rotor is coupled to at least one rotor support member in the plurality of rotor support members, where the at least one rotor support member is coupled to the central housing, the at least one of the frame support members, or a combination thereof and where the buoyant assembly is coupled to the central frame such that the rotating mast, the hub, and the plurality of rotor blades of the each rotor is above the water when the buoyant assembly floats on water and such that the plurality of rotor blades of the each rotor is oriented to direct a thrust in a direction toward a surface of the water when the buoyant assembly floats on water;

a plurality of solar cells where each solar cell comprises a sun-facing side, where the each solar cell is coupled to at least one frame support member in the plurality of frame support members where the at least one frame support member is coupled to the central housing and the buoyant assembly is coupled to the central frame such that the sun-facing side of the each solar cell is above the water when the buoyant assembly floats on water;

a battery electrically connected to the each solar cell and electrically connected to each motor in the plurality of rotors;

a tether having a length L coupled to the central housing at a first end and coupled to a sensor having a mass M at a second end, where the sensor is configured to sink in water and where the tether is coupled to the central housing at the first end and coupled to the sensor at the second end such that the second end of the tether is submerged in the water when the buoyant assembly floats on water, and where the multirotor mobile buoy has a center of gravity and a center of buoyancy when the buoyant assembly floats on water, and where the center of gravity is below the center of buoyancy when the buoyant assembly floats on water and the tether has the length L and the mass M; and

a computing system within the central housing where the computing system is configured to receive data from the sensor.

13. The multirotor mobile buoy of claim 12 where the where central housing has a vertical axis extending through the central housing when the buoyant assembly floats on water, and where a reference diameter D is perpendicular to the vertical axis and surrounds the central frame and the buoyant assembly, and the length L of the tether is at least 10 times greater than the reference diameter D.

14. The multirotor mobile buoy of claim 13 where the buoyant assembly generates one or more buoyant forces when the buoyant assembly floats on water, where each of the buoyant forces is parallel to the vertical axis, and where each plurality of rotor blades in each rotor in the plurality of rotors has a plane of rotation, and the plane of rotation is substantially perpendicular to the vertical axis.