Low strain pneumatic networks for soft robots

• US 10,639,801 B2
• Filed: 08/20/2014
• Issued: 05/05/2020
• Est. Priority Date: 08/20/2013
• Status: Active Grant

• Current Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Original Assignee: President and Fellows of Harvard College (Harvard Corporation)
• Inventors: Mosadegh, Bobak, Shepherd, Robert F., Whitesides, George M.
• Primary Examiner(s): Teka, Abiy
• Application Number:
  US14/464,396
• Publication Number:
  US 20150266186A1
• Time in Patent Office: 2,085 Days
• CPC Class Codes: B25J 15/0023 Gripper surfaces directly activated by a fluid flexible fingers B25J15/12
• CPC Class Codes: B25J 15/12 with flexible finger members
• CPC Class Codes: B25J 18/06 flexible
• CPC Class Codes: B25J 9/142 comprising inflatable bodies
• CPC Class Codes: B29C 65/70 by moulding using a particular moulding technique, see the relevant technique , e.g. by injection B29C45/14467
• CPC Class Codes: B29L 2009/00 Layered products
• CPC Class Codes: F15B 15/08 Characterised by the construction of the motor unit
• CPC Class Codes: F15B 15/103 using inflatable bodies that contract when fluid pressure is applied, e.g. pneumatic artificial muscles or McKibben-type actuators

Abstract

An actuator includes a plurality of chambers comprised of an extensible material, the chambers having interior side walls and exterior walls, wherein at least a portion of the interior side wall is separated from an interior side wall of an adjacent chamber; and a strain limiting base; and a channel that fluidically interconnects the plurality of chambers, wherein the interior walls are configured to be more compliant than the exterior walls.

Claims

1. An actuator, comprising:

a base comprising a strain limiting layer;

a plurality of unsupported chambers secured to the strain limiting layer, each chamber having interior side walls, exterior side walls, and a top wall, wherein the unsupported chambers do not share a common wall along a portion of the interior side walls;

a channel that fluidically interconnects the plurality of chambers; and

an inlet port for receiving a pressurizing fluid, wherein the interior side walls expand a greater amount relative to the exterior side walls and the top wall upon pressurization of the chambers to cause bending of the actuator around the strain limiting layer and cause said portion of the interior walls to touch each other.

2. The actuator of claim 1, wherein the exterior walls include exterior side walls having a thickness that is greater than a thickness of the interior side walls.

3. The actuator of claim 1, wherein the exterior walls include top walls having a thickness that is greater than a thickness of the interior side walls.

4. The actuator of claim 1, wherein the exterior walls are made from a materials having a greater stiffness than the interior side walls.

5. The actuator of claim 1, wherein the strain limiting layer comprises an inextensible, flexible layer.

6. The actuator of claim 5, wherein the strain limiting layer comprises an inextensible layer embedded in a layer of flexible polymer.

7. The actuator of claim 6, wherein the inextensible layer comprises a paper, a fabric or a polymer film.

8. The actuator of claim 7, wherein the paper or the fabric is provided as a matted sheet, a woven sheet or a fiber aligned along the length of the strain limiting layer.

9. The actuator of claim 1, wherein the strain limiting layer comprises an extensible, flexible material that is configured and arranged to be stiffer than the exterior walls of the chambers.

10. The actuator of claim 1, wherein the plurality of chambers are comprised of an elastomer.

11. The actuator of claim 1, wherein the actuator is powered by pressure provided by a gas or liquid source.

12. The actuator of claim 1, wherein the channel is positioned between the interior sidewalls of the plurality of chambers.

13. The actuator of claim 1, wherein the channel is located in the strain limiting layer and is positioned and arranged to fluidically connect the plurality of chambers.

14. The actuator of claim 1, wherein greater than 25% of the surface area of the interior side wall of the first chamber is separated from the interior side wall of the second chamber.

15. A method of actuation comprising:

providing the actuator according to claim 1; and

pressurizing the actuator to cause the actuator to actuate from a first resting position to a second actuated position.

16. The method of claim 15, wherein pressurizing causes the interior side walls to expand preferentially compared to the exterior walls.

17. The method of claim 15, wherein the actuation occurs in less than 1 second.

18. The method of claim 15, wherein the actuation occurs in less than 250 msec.

19. The method of claim 15, wherein the actuation occurs in less than 100 msec.

20. The method of claim 15, wherein the actuation is greater than 1 m/sec.

21. The method of claim 15, wherein the actuator undergoes a circumferential-expansion of less than 3% during the actuation.

22. The method of claim 15, wherein the actuator undergoes an energy loss of less than 10% between the actuated and unactuated state.

23. The method of claim 15, wherein the actuator is configured to be cycled more than 10000 times without failure.

24. The method of claim 15, wherein the actuator is configured to be cycled more than 200000 times without failure.

25. The method of claim 15, wherein the actuator is configured to cycle more than one million times without failure.

26. The method of claim 15, wherein the frequency of actuation is greater than 1 Hz.

27. The method of claim 15, wherein the frequency of actuation is greater than 2 Hz.

28. The method of claim 15, wherein the actuator bends along a circular trajectory below a threshold actuation rate and the tip of the actuator bends preferentially, causing the actuator to curl on itself above a threshold actuation rate.

29. A soft robot comprising:

a plurality of soft actuators according to claim 1; and

a connector having a plurality of fluidic inputs and a pressurizing inlet, wherein the pressurizing inlet is configured to receive fluid, and the inlet port of one of the plurality of soft actuators is reversibly coupled to one of the plurality of fluidic inputs.

30. The actuator of claim 1, wherein the inlet port is coupled to a solenoid valve that is configured to control whether the actuator is pressurized with compressed air or vented to atmosphere.

31. The actuator of claim 30, wherein the solenoid valve is coupled to the inlet port via tubing.

32. The actuator of claim 1, wherein the plurality of chambers are secured to the strain limiting layer along one face.