PHASED ARRAY BUCKLING ACTUATOR

• US 20110109198A1
• Filed: 11/09/2010
• Published: 05/12/2011
• Est. Priority Date: 11/10/2009
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Neal, Devin Michael, Asada, Haruhiko Harry
• Granted Patent: US 8,593,035 B2
• Time in Patent Office: Days
• US Class Current: 310/328
• CPC Class Codes: H02N 2/02 producing linear motion, e.g. actuators; Linear positioners ; Linear motors
• CPC Class Codes: H02N 2/043 Mechanical transmission means, e.g. for stroke amplification
• CPC Class Codes: H02N 2/105 Cycloid or wobble motors; Harmonic traction motors
• CPC Class Codes: Y10T 74/18888 Reciprocating to or from oscillating

Abstract

A harmonic buckling actuator is comprised of numerous buckling units engaged to a rotational track/gear. Each buckling unit includes two input translational actuators. One end of each input actuator is constrained to rotate about a rotational joint that is rigidly attached to a common ground. The other end of each input actuator is constrained to move with the other actuator of the same buckling unit along a single output axis via another rotational joint that is the output of the buckling unit. The inactivated, unforced configuration of each buckling unit is such that the input actuators are nearly collinear with the line segment connecting the unit'"'"'s grounded rotational joints. This line segment is parallel to the output axis of the track/gear. The buckling units are arrayed around the track/gear such that their outputs are spatially phased within the groves of the track/gear. Harmonic activation of the buckling units generates torque on the track/gear about its output axis. The hollow section of the track/gear encompasses a gear reducer such as a planetary gear box, cyclo-drive, or harmonic drive. The track/gear is coupled to the slow speed shaft of the reducer. The buckling unit supports are rigidly coupled to each other and to the gear box of the reducer. The high speed shaft is the output shaft of the entire harmonic buckling actuator.

Claims

1. A displacement amplification device, comprising:

a first buckling actuator unit tending to cause displacement of the first buckling actuator unit in a first direction when activated; and

a second buckling actuator unit tending to cause displacement of the second buckling actuator unit in a second direction when activated;

wherein asynchronous activation of the first and second buckling actuator units controls buckling direction and wherein one of the first and second buckling actuator units is forced beyond a zero displacement point by the other of the first and second buckling actuator units.

2. The displacement amplification device of claim 1, wherein the first and second buckling actuator units each comprise:

first and second input linear actuators;

a first rotational joint rigidly coupling one end of the first input linear actuator to a common ground;

a second rotational joint rigidly coupling one end of the second input linear actuator to the common ground; and

a third rotational joint coupling the other end of each of the first and second input linear actuators to each other.

3. The displacement amplification device of claim 2, wherein the first and second input linear actuators are piezoelectric actuators.

4. A displacement amplification device, comprising:

a plurality of buckling actuator units, wherein asynchronous activation of the plurality of buckling actuator units controls displacement direction,

wherein each of the buckling actuator units comprises;

first and second input linear actuators;

a first rotational joint rigidly coupling one end of the first input linear actuator to a common ground;

a second rotational joint rigidly coupling one end of the second input linear actuator to the common ground; and

a third rotational joint coupling the other end of each of the first and second input linear actuators to each other,

wherein the third rotational joint is coupled and arranged such that the third rotational joint displaces in either direction across a line defined by the first and second rotational joints with zero displacement being defined by the third rotational joint lying on the line defined by the first and second rotational joints,

wherein the third rotational joints of first and second buckling actuator units of the plurality of buckling actuators units are free to move in the same plane and are mechanically coupled to each other.

5. The displacement amplification device of claim 4, wherein activating the first buckling actuator unit of the plurality of buckling actuators units forces the second buckling actuator unit of the plurality of buckling actuator units from one side to the other of the zero displacement point of the second buckling actuator unit.

6. The displacement amplification device of claim 4, wherein the first and second buckling actuator units are spatially out of phase.

7. The displacement amplification device of claim 4, wherein the first and second input linear actuators of the first and second buckling actuator units are at a non-zero angle to the line defined by the first and second rotational joints of the first and second buckling actuator units, respectively, in an inactive state.

8. The displacement amplification device of claim 4, wherein the third rotational joints of the first and second buckling actuator units are both inside or both outside the lines defined by the first and second rotational joints of the first and second buckling actuator units.

9. The displacement amplification device of claim 4, wherein the lines defined by the first and second rotational joints of the first and second buckling actuator units are in parallel.

10. The displacement amplification device of claim 4, wherein an output displacement axes of each of the first and second buckling actuator units are collinear.

11. The displacement amplification device of claim 4, wherein the first and second buckling actuator units are substantially identical.

12. The displacement amplification device of claim 4, wherein an inactive, unforced minimum distance between the third rotational joint and the line defined by the first and second rotational joints in each of the first and second buckling actuator units are equal.

13. The displacement amplification device of claim 4, wherein the first and second input linear actuators are piezoelectric actuators.

14. A displacement amplification device, comprising:

a plurality of buckling actuator units, wherein asynchronous activation of the plurality of buckling actuator units controls displacement direction,

wherein each of the buckling actuator units comprise;

first and second input linear actuators;

a first rotational joint rigidly coupling one end of the first input linear actuator to a common ground;

a second rotational joint rigidly coupling one end of the second input linear actuator to the common ground; and

a third rotational joint coupling the other end of each of the first and second input linear actuators to each other,

wherein the third rotational joint is coupled and arranged such that the third rotational joint buckles in either direction across a line defined by the first and second rotational joints, and

wherein the plurality of buckling actuator units are engaged to a track and are harmonically activated to generate net force on the track.

15. The displacement amplification device of claim 14, wherein the track is gear-shaped such that the force generated by the buckling actuator units generates a torque output.

16. The displacement amplification device of claim 15, wherein the gear-shaped track is coupled to a slow speed shaft of a gear reducer.

17. The displacement amplification device of claim 16, wherein a gear box of the gear reducer is rigidly coupled to the common ground shared by the individual buckling actuator units.

18. The displacement amplification device of claim 16, wherein the gear reducer is encompassed by the gear-shaped track.

19. The displacement amplification device of claim 14, wherein the plurality of buckling actuator units are equally spaced apart along the track.

20. The displacement amplification device of claim 14, wherein the first and second input linear actuators are piezoelectric actuators.

21. A method of controlling a displacement direction of a displacement amplification device, comprising:

providing a plurality of buckling actuator units;

activating a first buckling actuator unit of the plurality of buckling actuator units such that a second buckling actuator unit of the plurality of buckling actuator units is forced from one side to the other of a zero displacement point of the second buckling actuator unit; and

activating the second buckling actuator unit such that a magnitude of the displacement of the first and second buckling actuator units is increased.

22. The method of claim 21, wherein each of the plurality of buckling actuator units comprise:

first and second input linear actuators;

a first rotational joint rigidly coupling one end of the first input linear actuator to a common ground;

a second rotational joint rigidly coupling one end of the second input linear actuator to the common ground; and

a third rotational joint coupling the other end of each of the first and second input linear actuators to each other.

23. The method of claim 22, wherein the third rotational joints of the first and second buckling actuator units are free to move in the same plane and are mechanically coupled to each other.

24. The method of claim 22, wherein when the first and second buckling actuator units are inactive, the first and second input linear actuators of the first and second buckling actuator units are at an angle to a line defined by the first and second rotational joints of the first and second buckling actuator units, respectively.