Passive torque balancing in a high-frequency oscillating system

Patent metadata

Field	Value
Publication number	US-9038942-B2
Application number	US-201113519901-A
Country	US
Kind code	B2
Filing date	Feb 11, 2011
Priority date	Feb 11, 2010
Publication date	May 26, 2015
Grant date	May 26, 2015

Abstract

A passively torque-balanced device includes (a) a frame; (b) a drivetrain including a drive actuator mounted to the frame and configured for reciprocating displacement, an input platform configured for displacement by the drive actuator, a plurality of rigid links, including a proximate link and remote links, wherein the rigid links are collectively mounted to the frame, and a plurality of joints joining the rigid links and providing a plurality of non-fully actuated degrees of freedom for displacement of the rigid links, the plurality of joints including a fulcrum joint that is joined both to the input platform and to the proximate rigid link; and (c) at least two end effectors respectively coupled with the remote links and configured for displacement without full actuation.

First claim

What is claimed is:

1. A passively torque-balanced device comprising:
a frame;
a powered and automated drive actuator mounted to the frame and configured for reciprocating displacement;
a fulcrum joint coupled with the powered drive actuator;
a proximate balancing link coupled with the powered drive actuator through the fulcrum joint and configured for displacement by the drive actuator;
a first plurality of rigid links coupled with the proximate balancing link at a first end region of the proximate balancing link;
a second plurality of rigid links coupled with the proximate balancing link at a second end region of the proximate balancing link, wherein the first and second end regions of the proximate balancing link respectively include opposite ends of the proximate balancing link;
a plurality of joints, wherein at least one joint couples the first plurality of rigid links with the proximate balancing link at the first end region of the proximate balancing link, wherein at least one other joint couples the second plurality of rigid links with the proximate balancing link at the second end region of the proximate balancing link, wherein a first set of additional joints couples the first plurality of rigid links with each other in series, and wherein a second set of additional joints couples the second plurality of rigid links with each other in series, wherein the joints provide the rigid links with a plurality of non-fully actuated degrees of freedom for displacement of the rigid links; and
at least two end effectors, wherein a first end effector is coupled with the first plurality of rigid links, and wherein a second end effector is coupled with the second plurality of rigid links, and wherein each end effector is configured for displacement without full actuation.

2. The device of claim 1 , wherein the joints provide at least one of the rigid links with at least three non-fully actuated degrees of freedom for displacement.

3. The device of claim 1 , wherein the end effectors comprise a pair of wings configured for generating aerodynamic lift for flight of the device via a flapping wing stroke effected by the reciprocating displacement of the drive actuator.

4. The device of claim 3 , wherein the wings are connected to the rigid links via spars, wherein the wings are passively pivotable about the longitudinal axis of the spars.

5. The device of claim 3 , wherein each dimension of the device is less than 10 cm.

6. The device of claim 1 , wherein the rigid links comprise rigid layer segments sandwiched around a comparatively flexible strip, and wherein gaps are provided between rigid layer segments, exposing the flexible strip to serve as the joints in the gaps.

7. The device of claim 6 , wherein the rigid layer segments comprise a fiber-reinforced composite.

8. The device of claim 6 , wherein the flexible strip comprises polyimide.

9. The device of claim 1 , further comprising a voltage source mounted to the frame and coupled with the drive actuator to power the reciprocating displacement of the drive actuator.

10. The device of claim 1 , further comprising at least one device selected from a camera, a sensor, an electronic communication transmitter, and an electronic communication receiver mounted to the frame.

11. The device of claim 1 , further comprising a control actuator coupled with at least one of the rigid links, supplementing and configured to steer the device when the device is displaced by the end effectors.

12. The device of claim 1 , wherein the drive actuator comprises a piezoelectric bimorph cantilever.

13. A method for generating passively torque-balanced displacement, the method comprising:
providing a device comprising:
i)is frame;
ii) a powered and automated drive actuator mounted to the frame;
iii) a fulcrum joint coupled with the powered drive actuator;
iv) a proximate balancing link coupled with the powered drive actuator through the fulcrum joint;
v) a first plurality of rigid links coupled with the proximate balancing link at a first end region of the proximate balancing link;
vi) a second plurality of rigid links coupled with the proximate balancing link at a second end region of the proximate balancing link, wherein the first and second end regions of the proximate balancing link respectively include opposite ends of the proximate balancing link;
vii) a plurality of joints, wherein at least one joint couples the first plurality of rigid links with the proximate balancing link at the first end region of the proximate balancing link, wherein at least one other joint couples the second plurality of rigid links with the proximate balancing link at the second end region of the proximate balancing link, wherein a first set of additional joints couples the first plurality of rigid links with each other in series, and wherein a second set of additional joints couples the second plurality of rigid links with each other in series; and
viii) at least a first and second end effector, wherein the first end effector is coupled with the first plurality of rigid links, and wherein the second end effector is coupled with the second plurality of rigid links;

generating reciprocating displacement of the drive actuator;
mapping the reciprocating displacement of the drive actuator
through the fulcrum joint to the proximate balancing link to displace the proximate balancing link;
mapping the displacement of the proximate balancing link (a) through at least one joint to displace rigid links in the first plurality of rigid links without full actuation and (b) through at least one additional joint to displace rigid links in the second plurality of rigid links without full actuation; and
mapping the displacement of the first and second remote links to the end effectors respectively joined to the first and second remote links to reciprocatively displace the end effectors.

14. The method of claim 13 , further comprising displacing the device by the reciprocative displacement of the end effectors.

15. The method of claim 14 , wherein the end effectors are wings, and further comprising generating lift and flight of the device by the reciprocative displacement of the wings.

16. The method of claim 13 , further comprising balancing torque realized at each end effector by passively altering apportionment of power from the displacement of the drive actuator at the proximate link.

17. The method of claim 16 , wherein the end effectors are reciprocatively displaced with non-symmetric trajectories.

18. The method of claim 13 , wherein the drive actuator reciprocally displaced at a resonant frequency of the device.

19. The method of claim 13 , wherein the drive actuator is reciprocally displaced at an oscillation rate of at least 40 Hz.

20. The method of claim 13 , wherein the drive actuator is reciprocated with a sinusoidal displacement over time.

Assignees

• Sreetharan Pratheev Sabaratnam
• Wood Robert J
• Harvard College

Inventors

• Sreetharan Pratheev Sabaratnam
• Wood Robert J

Classifications

• B64C39/028

  Micro-sized aircraft · CPC title

• B64C33/02 Primary

  Wings; Actuating mechanisms therefor · CPC title

• Y10T74/18968

  Flexible connections · CPC title

• B64C33/00

  Ornithopters · CPC title

• Y10T74/18928

  Straight line motions · CPC title