Hydraulically amplified self-healing electrostatic actuators

Patent metadata

Field	Value
Publication number	US-10995779-B2
Application number	US-201816496234-A
Country	US
Kind code	B2
Filing date	Mar 22, 2018
Priority date	Mar 22, 2017
Publication date	May 4, 2021
Grant date	May 4, 2021

Abstract

Hydraulically-amplified, self-healing, electrostatic actuators that harness electrostatic and hydraulic forces to achieve various actuation modes. Electrostatic forces between electrode pairs of the actuators generated upon application of a voltage to the electrode pairs draws the electrodes in each pair towards each other to displace a liquid dielectric contained within an enclosed internal cavity of the actuators to drive actuation in various manners. The electrodes and the liquid dielectric form a self-healing capacitor whereby the liquid dielectric automatically fills breaches in the liquid dielectric resulting from dielectric breakdown.

First claim

We claim:

1. An electro-hydraulic actuator, comprising,
a deformable shell that defines an enclosed internal cavity;
a liquid dielectric contained within the enclosed internal cavity;
a first electrode disposed over a first side of the enclosed internal cavity; and
a second electrode disposed over a second side of the enclosed internal cavity, wherein
the first and second electrodes are configured such that an electrostatic force between the first and second electrodes upon application of a voltage to one of the first and second electrodes draws the first and second electrodes towards each other to displace the liquid dielectric within the enclosed internal cavity, are disposed comprises an active area of the deformable shell,

wherein a surface area of the deformable shell over which the first and second electrodes are not disposed comprises an inactive area of the deformable shell,
wherein the electrostatic force between the first and second electrodes is configured to displace the liquid dielectric within the enclosed internal cavity from the active area of the shell to the inactive area of the shell,
wherein the first and second electrodes comprise a first pair of electrodes,
wherein the actuator comprises one or more additional pairs of electrodes that are each disposed over one or more additional active areas of the flexible shell,
wherein each adjacent pair of the active areas is spaced by an inactive area,
wherein the internal cavity comprises a plurality of sub-cavities, wherein each sub-cavity is surrounded by one or the active areas and one of the inactive areas, and
wherein the liquid dielectric is impassable from one sub-cavity to another sub-cavity.

2. The actuator of claim 1 , wherein the deformable shell further includes a central inactive area that is surrounded by the first pair of electrodes and the one or more additional pairs of electrodes.

3. A system, comprising:
a stack of a plurality of the actuators of claim 1 , wherein the first actuators in the stack are electrically connected in parallel or series, and wherein the second actuators in the stack are electrically connected in parallel or series.

4. The actuator of claim 1 , wherein a first portion of the deformable shell on the first side of the internal cavity comprises a first stiffness, wherein a second portion of the deformable shell on the second side of the internal cavity comprises a second stiffness, and wherein the first stiffness is greater than the second stiffness.

5. The actuator of claim 1 , wherein the first and second electrodes, the deformable shell, and the liquid dielectric form a self-healing capacitor, and wherein the liquid dielectric is configured for automatically filing breaches in the liquid dielectric resulting from dielectric breakdown.

6. A method of using an electro-hydraulic actuator, comprising applying a voltage to one of a first and a second electrode of the actuator to generate an electrostatic force between the first and second electrodes;
drawing the first and second electrodes towards each other using the electrostatic force;
displacing, during the drawing, a liquid dielectric contained within a flexible shell and disposed between the first and second electrodes; and
flexing a portion of the flexible shell with the displaced liquid dielectric,
wherein a surface area of the flexible shell over which the first and second electrodes are disposed comprises an active area of the flexible shell, wherein a surface area of the flexible shell over which the first and second electrodes are not disposed comprises an inactive area of the flexible shell, and wherein the displacing includes:
displacing the liquid dielectric from the active area of the shell to the inactive area of the shell,
wherein the first and second electrodes comprise a first pair of electrodes,
wherein one or more additional pairs of electrodes are disposed over additional active areas of the flexible shell and
wherein each adjacent pair of the active areas is spaced by an inactive area, and

wherein the displacing includes;
displacing the liquid dielectric from the active areas to the inactive areas; and
drawing the electrodes in each adjacent pair of electrodes towards each other in response to the liquid dielectric being displaced from the active areas to the inactive areas.

7. The method of claim 6 , wherein the electrostatic force extends in a direction of a first reference axis, and wherein the displacing includes:
displacing the liquid dielectric in a direction of a second reference axis that is perpendicular to the first reference axis.

8. The method of claim 7 , wherein the flexing includes:
urging the portion of the flexible shell along the second reference axis.

9. The method of claim 8 , further including;
inhibiting flexure of the flexible shell in a direction of a third reference axis that is perpendicular to the first and second reference axes.

10. The method of claim 6 , wherein the flexing includes elastically flexing the portion of the flexible shell.

11. The method of claim 6 , wherein the flexing occurs free of elastically stretching the portion of the flexible shell.

12. The method of claim 6 , further including:
measuring a first capacitance of one of the first and second electrodes before the applying;
measuring a second capacitance of the one of the first and second electrodes after the applying, and
using a difference between the first and second capacitances to determine a strain of the one of the first and second electrodes relative to the other of first and second electrodes during the displacing.

13. The method of claim 6 , wherein the displacing includes;
displacing the liquid dielectric from one of the active areas of the shell to another of the active areas of the shell, wherein a voltage is not applied to the pair of electrodes of the another active area of the shell.

14. The method of claim 6 , further including,
bending the actuator in response to the drawing the electrodes in each adjacent pair of electrodes toward each other.

15. The method of claim 14 , further including:
twisting the actuator in response to the drawing the electrodes in each adjacent pair of electrodes towards each other.

16. An electro-hydraulic actuator, comprising:
a deformable shell that defines an enclosed internal cavity;
a liquid dielectric contained within the enclosed internal cavity;
a first electrode disposed over a first side of the enclosed internal cavity; and
a second electrode disposed over a second side of the enclosed internal cavity,
wherein the first and second electrodes are configured such that an electrostatic force
between the first and second electrodes upon application of a voltage to one of the first and second electrodes draws the first and second electrodes towards each other to displace the liquid dielectric within the enclosed internal cavity,

wherein a first portion of the deformable shell on the first side of the internal cavity comprises a first stiffness,
wherein a second portion of the deformable shell on the second side of the internal cavity comprises a second stiffness, and
wherein the first stiffness is greater than the second stiffness.

17. The actuator of claim 16 , wherein a surface area of the deformable shell over which the first and second electrodes are disposed comprises an active area of the deformable shell, wherein a surface area of the deformable shell over which the first and second electrodes are not disposed comprises an inactive area of the deformable shell, and wherein the electr

Assignees

• Univ Colorado Regents

Inventors

• Keplinger Christoph Matthias
• Acome Eric Lucas
• Kellaris Nicholas Alexander
• Mitchell Shane Karl

Classifications

• F15B2211/20515

  Electric motor · CPC title

• F15B21/08

  Servomotor systems incorporating electrically operated control means (F15B21/02, {F15B21/065} take precedence) · CPC title

• F15B15/18

  Combined units comprising both motor and pump · CPC title

• H01G5/0132

  Liquid dielectrics · CPC title

• F15B21/06

  Use of special fluids, e.g. liquid metal; Special adaptations of fluid-pressure systems, or control of elements therefor, to the use of such fluids · CPC title