FLAPPING WING AERIAL VEHICLES

• US 20150307191A1
• Filed: 04/28/2015
• Published: 10/29/2015
• Est. Priority Date: 04/28/2014
• Status: Active Grant

• Current Assignee: University of Maryland, College Park
• Original Assignee: Daedalus Flight Systems LLC, University of Maryland, College Park
• Inventors: SAMUEL, Paul D., FARUQUE, Imraan, HUMBERT, James Sean
• Granted Patent: US 10,017,248 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B64C 33/02 Wings; Actuating mechanisms therefor
• CPC Class Codes: B64C 39/024 of the remote controlled vehicle type, i.e. RPV
• CPC Class Codes: B64U 10/40 Ornithopters

Abstract

An autonomous flapping wing aerial vehicle can have a vehicle body, a pair of flapping wings, tunable wing hinges, and elastic drive mechanisms. The tunable wing hinges can be coupled to the flapping wings. Each wing hinge can be constructed to deliver a force to a respective one of the flapping wings to alter end points of a stroke thereof. The elastic drive mechanisms can rotate the flapping wings about pivot points to produce the strokes of the flapping wings. The elastic drive mechanism can be driven at or near a resonance thereof. Alterations to the strokes of the flapping wings produced by the combined effect of the tunable wing hinges and the elastic drive mechanisms, operating in parallel, can provide steering control of the aerial vehicle.

Claims

1. A flapping wing aerial vehicle comprising:

a vehicle body;

a pair of flapping wings;

tunable wing hinges coupled to the flapping wings, each wing hinge being constructed to deliver a force to a respective one of the flapping wings to alter end points of a stroke thereof; and

elastic drive mechanisms that rotate the flapping wings about pivot points to produce the strokes of the flapping wings.

2. The flapping wing aerial vehicle of claim 1, further comprising rotational drives that rotate the wing hinges about a first axis perpendicular to a direction of the flapping so as to change an inclination of a plane of the stroke of the flapping wing.

3. The flapping wing aerial vehicle of claim 2, further comprising a controller configured to control the tunable wing hinges to alter the end points and/or the inclination planes of the flapping wing strokes to produce changes in at least one of roll, pitch, yaw, surge, sideslip, and heave.

4. The flapping wing aerial vehicle of claim 1, wherein each tunable wing hinge includes an actuator magnet coupled to a drive portion of the respective flapping wing and an actuator coil, the actuator coil being configured to apply a magnetic force to the actuator magnet to alter the end points of the flapping wing stroke.

5. The flapping wing aerial vehicle of claim 4, wherein a magnetic field of the actuator magnet is parallel to a magnetic field of the respective actuator coil when the respective flapping wing is at a center of its stroke.

6. The flapping wing aerial vehicle of claim 1, wherein each elastic drive mechanism comprises a nonlinear spring element coupling a drive portion of the respective flapping wing to a rigid drive arm.

7. The flapping wing aerial vehicle of claim 6, wherein the nonlinear spring element is stiffer when the respective flapping wing is at a center of its stroke than when the respective flapping wing is at either of the end points of its stroke.

8. The flapping wing aerial vehicle of claim 6, wherein the nonlinear spring element comprises a torsion spring or a cantilever spring.

9. The flapping wing aerial vehicle of claim 6, further comprising a motor and a power transmission device coupling the motor to the drive arm of each elastic drive mechanism, the power transmission device converting rotational motion of the motor into linear motion at each drive arm.

10. The flapping wing aerial vehicle of claim 9, wherein the power transmission device comprises a Cardan drive mechanism.

11. The flapping wing aerial vehicle of claim 9, wherein the power transmission device comprises a gear train and a crank arm, one end of the crank arm being coupled to the gear train and an opposite end of the crank arm being coupled to each of the drive arms.

12. The flapping wing aerial vehicle of claim 9, further comprising a controller configured to control a speed of the motor to drive each of the elastic drive mechanisms at a frequency within a range from 10% below their resonance frequency to 1% above their resonance frequency.

13. The flapping wing aerial vehicle of claim 12, wherein a root portion of each of the flapping wings comprises a root spring element, and the controller is configured to control a speed of the motor to drive the flapping wings at a frequency within 5% of their resonance frequency.

14. The flapping wing aerial vehicle of claim 12, further comprising a sensor that measures angular rate of the aerial vehicle, wherein the controller is configured to control actuation of the flapping wings through the tunable wing hinges and the elastic drive mechanisms so as to cause a change in at least one of yaw rate, roll rate, and pitch rate.

15. The flapping wing aerial vehicle of claim 1, wherein each of the flapping wings comprises a dihedral coupled with a root spring element having vertical flexibility.

16. A method for operating a flapping wing aerial vehicle, the aerial vehicle comprising a pair of flapping wings coupled to tunable wing hinges and elastic drive mechanisms that rotate the flapping wings about pivot points, the method comprising:

driving the elastic drive mechanisms at frequencies within a range from 10% below their resonance frequency to 1% above their resonance frequency to cause strokes of the flapping wings; and

applying forces at the tunable wing hinges to alter end points of the flapping wing strokes and/or changing orientations of the tunable wing hinges to alter inclinations of respective planes of the flapping wing strokes.

17. The method of claim 16, wherein said applying forces and/or changing orientations to each tunable wing hinge is effective to alter at least one of roll, pitch, yaw, surge, sideslip, and heave of the autonomous flapping wing aerial vehicle.

18. The method of claim 16, wherein the applying forces comprises passing a current through actuator coils spaced from actuator magnets, which are coupled to drive portions of the flapping wings, so as to apply the forces to the tunable wing hinges.

19. The method of claim 16, wherein the changing orientations comprises rotating each tunable wing hinge about a respective axis perpendicular to a direction of the flapping so as to alter the inclination of the respective plane of the flapping wing stroke.

20. The method of claim 16, wherein each elastic drive mechanism comprises a nonlinear spring element coupled to the respective flapping wing, and the driving is performed using a motor.

21. The method of claim 16, wherein the applying forces to each tunable wing hinge causes at least one of:

a change in a stroke amplitude of one of the flapping wings with respect to the other of the flapping wings so as to produce a change in roll of the autonomous flapping wing aerial vehicle;

a bias of stroke motion of the flapping wings fore or aft so as to produce a change in pitch of the autonomous flapping wing aerial vehicle; and

changes in the stroke amplitudes of the flapping wings so as to produce a change in heave of the autonomous flapping wing aerial vehicle.

22. The method of claim 21, wherein:

the applying forces comprises passing a current through actuator coils disposed with respect to actuator magnets, which are coupled to drive portions of the flapping wings, so as to apply the forces to the tunable wing hinges;

the magnetic field of each actuator magnet is parallel to the magnetic field of the respective actuator coil when the respective flapping wing is at a center of its stroke; and

the changes in stroke amplitude and/or the bias of the stroke motion are caused by applying a direct current and/or time-varying current to the actuator coils.

23. The method of claim 16, further comprising measuring a position of each flapping wing, wherein the applying forces is responsive to the measured positions.

24. A wing-flapping device for an aerial vehicle, the wing-flapping device comprising:

(a) a pair of wing support members, each wing support member supporting a root portion of a flapping wing and being capable of rotation about a flap axis;

(b) a lift-generating mechanism comprising;

(b1) a drive mechanism that produces reciprocating motion; and

(b2) a pair of flexures, each flexure being coupled to the drive mechanism and to the respective wing support member such that the reciprocating motion produces a corresponding rotation of the wing support member about the flap axis; and

(c) a steering mechanism comprising;

(c1) one or more actuator magnets, each actuator magnet being coupled to one of the wing support members;

(c2) a pair of actuator coils, each actuator coil being configured to provide a magnetic force to the one or more actuator magnets to alter the rotation of the respective wing support member about the flap axis; and

(c3) a pair of bearings, each bearing supporting a respective one of the actuator coils and the respective wing support member, each bearing having a first rotational axis perpendicular to a second rotational axis of the respective wing support member about the flap axis.

25. The device of claim 24, wherein a magnetic field of each actuator magnet is parallel to a magnetic field of the respective actuator coil when the respective flapping wing is at a center of its stroke.

26. The device of claim 24, further comprising a controller configured to control a motor to drive the lift-generating mechanism at a frequency within a range from 10% below a resonant frequency thereof to 1% above said resonance frequency, and to control the steering mechanism to alter end points and/or inclination of wingstrokes of the flapping wings to produce changes in at least one of roll, pitch, yaw, surge, sideslip, and heave.

27. The device of claim 26, further comprising wing position sensors that generate signals indicative of a position of each flapping wing, wherein the controller is configured to control the steering mechanism to apply forces to the flapping wings responsively to the wing position sensor signals.

28. The device of claim 24, wherein each flexure comprises a nonlinear spring element that is stiffer when the respective flapping wing is at a center of its stroke than when the respective flapping wing is at either of the end points of its stroke.