Artificial muscle drive unit with load bearing for improved performance

Abstract

To provide an artificial muscle drive unit, and a method for operating the artificial muscle drive unit.SOLUTION: An artificial muscle drive unit comprises a base and an artificial muscle arranged on the base. The artificial muscle comprises an expandable reservoir and fluid. The fluid is movable within the expandable reservoir in order to switch the artificial muscle between a non-actuated state in which a dimension in a movement direction of the artificial muscle is a minimum value and an actuated state in which the dimension of the artificial muscle is a maximum value. The artificial muscle drive unit also comprises a load support body arranged on the base, and the load support body has a dimension in the movement direction that is larger than or equal to the minimum value.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present specification relates generally to an artificial muscle drive unit with load-bearing support for improved performance. [Background technology]

[0002] Current robotics technology relies on rigid components, such as servo motors, to perform tasks, often in structured environments. This rigidity presents limitations in many robotic applications, due at least in part to the power-to-weight ratio of servo motors and other rigid robotic devices. The field of soft robotics seeks to ameliorate these limitations by using soft actuators, such as artificial muscles. Artificial muscles attempt to mimic the versatility, performance, and reliability of biological muscles. Some artificial muscles use fluid-based actuators. For example, some artificial muscles perform mechanical work on a load by pumping fluid into or out of a volume. In the presence of a load, the operation of such fluid-based artificial muscles can be compromised if the artificial muscle encounters a load in an unstretched state.

[0003] Therefore, there is a demand for an artificial muscle drive unit that is structured to avoid the presence of loads that would interfere with the operation of the artificial muscle. Summary of the Invention

[0004] In one embodiment, the artificial muscle drive unit includes a base and an artificial muscle disposed on the base. The artificial muscle includes an expandable reservoir and a fluid. The fluid is movable within the expandable reservoir to switch the artificial muscle between an unactuated state, in which a dimension of the artificial muscle in a direction of movement is at a minimum, and an actuated state, in which the dimension of the artificial muscle is at a maximum. The artificial muscle drive unit also includes a load support disposed on the base, the load support having a dimension in the direction of movement equal to or greater than the minimum.

[0005] In another embodiment, an artificial muscle device includes one or more actuation platforms interleaved with one or more mounting platforms to form one or more actuation cavities between one or more pairs of platforms. Each platform pair includes an individual mounting platform and an individual actuation platform. One or more artificial muscles are disposed in each of the one or more actuation cavities. Each of the one or more artificial muscles includes an expansion reservoir and a fluid. The fluid is movable within the expansion reservoir to switch the one or more artificial muscles between an unactuated state in which the artificial muscle has a minimum dimension in a direction of movement and an actuated state in which the artificial muscle has a maximum dimension in the direction of movement. A load support is disposed in at least one of the one or more actuation cavities, the load support having a dimension in the direction of movement that is equal to or greater than the minimum dimension.

[0006] In another embodiment, the artificial muscle device includes one or more actuation platforms interleaved with one or more mounting platforms to form one or more actuation cavities between one or more pairs of platforms. Each platform includes an individual mounting platform and an individual actuation platform. The artificial muscle device also includes one or more artificial muscles disposed in each of the one or more actuation cavities. Each of the one or more artificial muscles includes an expansion reservoir and a fluid. The fluid is movable within the expansion reservoir to actuate the one or more artificial muscles between an unactuated state, in which the artificial muscle has a minimum dimension in a direction of movement, and an actuated state, in which the artificial muscle has a maximum dimension in the direction of movement. The artificial muscle device also includes a load support disposed in at least one of the one or more actuation cavities, the load support having a dimension in the direction of movement equal to or greater than the minimum dimension.

[0007] Yet another embodiment is a method of actuating an artificial muscle drive unit, the method including positioning the artificial muscle drive unit relative to a load source such that the load source applies a force to a load support of the artificial muscle drive unit. The load support is positioned relative to the artificial muscle of the artificial muscle drive unit such that no force is directly applied to an expansible reservoir of the artificial muscle when the artificial muscle is in an unactuated state. The method also includes manipulating a fluid disposed within the expansible reservoir of the artificial muscle such that at least a portion of the expansible reservoir elongates in a direction of movement prior to encountering the force applied to the load support and continues to elongate in the direction of movement when encountering the force applied to the load support, thereby applying the artificial muscle force to the load source.

[0008] These and additional features provided by the embodiments described herein will be more fully understood in light of the following detailed description, taken in conjunction with the drawings. [Brief description of the drawings]

[0009] The embodiments depicted in the drawings are illustrative in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, in which like structure is indicated with like reference numerals and in which:

[0010] [Figure 1A] FIG. 2A is a schematic diagram of an artificial muscle drive unit including a load support in an unactuated state, according to one or more embodiments shown and described herein. [Figure 1B] FIG. 1B is a schematic diagram illustrating the artificial muscle drive unit of FIG. 1A in a partially actuated state, according to one or more embodiments shown and described herein. [Figure 1C] FIG. 1B is a schematic diagram illustrating the artificial muscle drive unit of FIG. 1A in a fully actuated state, according to one or more embodiments shown and described herein. [Diagram 2]FIG. 1A is a schematic diagram illustrating an exploded view of an example artificial muscle, according to one or more embodiments shown and described herein. [Diagram 3] FIG. 2 is a schematic diagram illustrating a top view of the artificial muscle of FIG. 1, according to one or more embodiments shown and described herein. [Figure 4A] FIG. 4 is a schematic diagram illustrating a cross-sectional view of the artificial muscle of FIGS. 2 and 3 taken along line 3-3 in FIG. 3 in an unactuated state, in accordance with one or more embodiments shown and described herein. [Figure 4B] FIG. 3 is a schematic diagram illustrating a cross-sectional view of the artificial muscle of FIG. 2 along line 3-3 in FIG. 3 in an actuated state, according to one or more embodiments shown and described herein. [Figure 5A] FIG. 1C is a schematic diagram illustrating a cross-sectional view of another example artificial muscle in an unactuated state, according to one or more embodiments shown and described herein. [Figure 5B] FIG. 5B is a schematic diagram illustrating a cross-sectional view of the artificial muscle of FIG. 5A in an actuated state, according to one or more embodiments shown and described herein. [Figure 6A] FIG. 1A is a schematic diagram illustrating a top view of an exemplary artificial muscle stack comprising multiple artificial muscle layers arranged in a coaxial alignment, according to one or more embodiments shown and described herein. [Figure 6B] FIG. 5B is a schematic diagram illustrating a side view of the artificial muscle stack of FIG. 6A along line 5B-5B in an unactuated state, in accordance with one or more embodiments shown and described herein. [Figure 6C] FIG. 5B is a schematic diagram illustrating a side view of the artificial muscle stack of FIG. 5A along line 5B-5B in an actuated state, according to one or more embodiments shown and described herein. [Figure 7A] FIG. 1A is a schematic diagram illustrating a top view of an exemplary artificial muscle stack comprising multiple artificial muscle layers arranged in an alternating offset arrangement, according to one or more embodiments shown and described herein. [Figure 7B]FIG. 7B is a schematic diagram illustrating a side view of the artificial muscle stack of FIG. 7A along line 6B-6B in an unactuated state, in accordance with one or more embodiments shown and described herein. [Figure 7C] FIG. 7B is a schematic diagram illustrating a side view of the artificial muscle stack of FIG. 7A along line 6B-6B in an actuated state, according to one or more embodiments shown and described herein. [Figure 7D] FIG. 6D is a schematic diagram illustrating a side view of the artificial muscle stack of FIG. 7A along line 6D-6D in an unactuated state, in accordance with one or more embodiments shown and described herein. [Figure 7E] FIG. 6D is a schematic diagram illustrating a side view of the artificial muscle stack of FIG. 7A along line 6D-6D in an unactuated state, in accordance with one or more embodiments shown and described herein. [Figure 8] FIG. 1A is a schematic diagram illustrating a top view of an example artificial muscle stack with multiple artificial muscle layers arranged in an alternating offset arrangement, plus circumferential artificial muscles, according to one or more embodiments shown and described herein. [Figure 9A] FIG. 1A is a schematic diagram illustrating a cross section of a layered actuation structure comprising an artificial muscle in an unactuated state, according to one or more embodiments shown and described herein. [Figure 9B] FIG. 9B is a schematic diagram illustrating an artificial muscle in an actuated state with a layered actuation structure of FIG. 9A , according to one or more embodiments shown and described herein. [Figure 10] FIG. 2 is a schematic diagram of an exemplary layered actuation structure according to one or more embodiments shown and described herein. [Figure 11] FIG. 2 is a schematic diagram of another exemplary layered actuation structure according to one or more embodiments shown and described herein. [Figure 12] FIG. 5 shows plots of force versus displacement for the artificial muscles shown in FIGS. 2-4B for the same artificial muscle when used in combination with a load support and when not used in combination with a load support, in accordance with one or more embodiments shown and described herein. [Figure 13]FIG. 12 is a schematic diagram of an actuation system for operating the artificial muscles of the layered actuation structure of FIGS. 9A-11, according to one or more embodiments shown and described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The embodiments described herein are directed to an artificial muscle drive unit that includes a base and an artificial muscle disposed on the base. The artificial muscle may be controllably deformable to provide a force in a direction of movement to an external object (e.g., a load source). The artificial muscle includes an expandable reservoir and a fluid, the fluid being movable within the expandable reservoir, such that the artificial muscle can be switched from an inactive state, in which the distance between the outer surface of the expandable reservoir and the base in the direction of movement is a minimum, to an active state, in which the distance between the outer surface of the expandable reservoir and the base in the direction of movement is a maximum (assuming no load is encountered by the artificial muscle that would prevent the expansion of the expandable reservoir). The artificial muscle drive unit described herein further includes a load support disposed on the base. The load support has a dimension in the direction of movement that is equal to or greater than the minimum value, and the load support is disposed relative to the artificial muscle such that when a load is applied to the artificial muscle drive unit, no force is applied to the expandable reservoir if the artificial muscle is in an inactive state.

[0012] In embodiments, an artificial muscle may be in a partially actuated state when the expandable reservoir encounters a load (e.g., a state in which the distance between the exterior surface of the expandable reservoir and the base in the direction of movement is halfway between a minimum and a maximum value). Avoiding load on the expandable reservoir when the artificial muscle is in an unactuated state may facilitate a desired movement pattern of fluid disposed within the expandable reservoir to transition from an unactuated state to an actuated state. That is, when the expandable reservoir encounters an external force in an unactuated state, this may affect the distribution of fluid within the expandable reservoir, thereby preventing the fluid from moving in a pattern that maximizes the stretch of the expandable reservoir in the direction of movement. Avoiding such inhibition of an unactuated artificial muscle may improve force and displacement output, thereby improving the performance of a device incorporating it.

[0013] 1A, 1B, and 1C, an artificial muscle drive unit 10 is shown in schematic form. The artificial muscle drive unit 10 includes a base 12 and an artificial muscle 14 disposed on the base 12. FIG. 1A shows the artificial muscle drive unit 10 with the artificial muscle 14 in an unactuated state. FIG. 1B shows the artificial muscle drive unit 10 with the artificial muscle 14 in a partially actuated state. FIG. 1C shows the artificial muscle drive unit 10 in an actuated state. The artificial muscle 14 includes an expandable reservoir 16 and a fluid 18 disposed within the expandable reservoir 16. The expandable reservoir 16 and the fluid 18 may include a variety of different shapes depending on the implementation. For example, in an embodiment, the artificial muscle 14 is in fluid communication with an external fluid source (e.g., a pump, not shown), and the external fluid source may be controlled to adjust the volume of the fluid contained within the expandable reservoir 16. In such an embodiment, at least a portion of the expandable reservoir 16 may be constructed of a flexible material such that the expandable reservoir expands or contracts along the direction of movement 22 in response to variations in the amount of fluid 18 disposed in the expandable reservoir 16.

[0014] In an embodiment, the artificial muscle 14 includes a closed fluid system, where the volume of fluid 18 disposed in the expansion reservoir 16 is fixed, but the distribution of fluid 18 is manipulated to change the shape of the expansion reservoir 16. In some embodiments of such a closed fluid system, the expansion reservoir 16 comprises the entire volume containing fluid 18 (e.g., the expansion reservoir constitutes the entire vessel that holds fluid 18). In some embodiments of such a closed fluid system, the expansion reservoir 16 comprises a portion of the volume containing fluid 18 (e.g., only a portion of the vessel that holds fluid 18 (corresponding to the expansion reservoir) may move in the movement direction 22). For example, in an embodiment, the expansion reservoir 16 includes an electrode portion and an expandable portion, and the distribution of fluid 18 may be manipulated to elongate the expandable portion in the movement direction 22 by adjusting the potential between the electrodes of the electrode portion to change the spacing between the electrodes. In an embodiment, the artificial muscle 14 comprises a hydraulically amplified self-healing electrostatic (HASEL) actuator as described in the article entitled "Hydraulically amplified self-healing electrostatic actuators with muscle-like performance" by E. Acome, S.K. Mitchell, T.G. Morrissey, M.B. Emmett, C. Benjamin, M. King, M. Radakovitz, and C. Keplinger (Science, January 5, 2018: Vol. 359, Issue 6371, pp. 61-65). In an embodiment, the artificial muscle 14 comprises an artificial muscle 100, 100' as described herein. It should be understood that the artificial muscle drive unit 10 may comprise any type of fluid-based artificial muscle, and the exemplary artificial muscles described herein should not be construed to limit the application of the present disclosure to any particular type of artificial muscle.

[0015] Further, it should be understood that the artificial muscle driving unit 10 shown in Figures 1A, 1B, and 1C includes only a single artificial muscle for purposes of discussion. In embodiments, the artificial muscle driving unit 10 includes a plurality of artificial muscles, including any number (e.g., tens, hundreds, thousands, hundreds of thousands, etc.) of artificial muscles. Such a plurality of artificial muscles can be combined with each other in any structural arrangement. For example, in embodiments, the artificial muscle 14 shown in Figures 1A, 1B, and 1C comprises a plurality of artificial muscles 100 described herein arranged in either an artificial muscle stack 201, 301, 301' described herein (Figures 6A-8) or a layered actuation structure 500 described herein (Figures 9A-11). Although exemplary structures of such an assembly of artificial muscles are described in detail herein, it should be understood that other artificial structures and arrangements are contemplated within the scope of the present disclosure.

[0016] In an embodiment, the volume and / or distribution of fluid 18 within the expansible reservoir 16 is actively controlled to manipulate the shape of the expansible reservoir 16 such that the artificial muscle 14 generates a desired motion pattern and force. In the embodiment shown in FIGS. 1A, 1B, and 1C, for example, the distribution of fluid 18 is manipulated to change a dimension 32 of the artificial muscle 14 in the direction of movement 22 (e.g., to thereby apply a force in the direction of movement 22 to an object 26 in contact with the artificial muscle drive unit 10). The exact location at which the dimension 32 of the artificial muscle 14 is measured depends on the design of the artificial muscle 14 and the force the artificial muscle 14 is designed to impart to an object 26 in contact with the artificial muscle drive unit 10, and can vary depending on the implementation. In the depicted embodiment, for example, the dimension 32 is measured as the linear distance between different points on the outer surface 20 of the artificial muscle 14 (e.g., the outer surface 20 of the expansible reservoir 16) along a central axis 34 that extends parallel to the direction of movement 22. In an embodiment, central axis 34 can represent a location of maximum dimensional change between the unactuated state shown in FIG. 1A and the actuated state shown in FIG. 1B due to the configuration of artificial muscle 14. It is contemplated that other embodiments may measure dimension 32 away from central axis 34 and / or in a direction other than direction of movement 22.

[0017] As shown in FIG. 1A, when the artificial muscle drive unit 10 is in an unactuated state, the dimension 32 has a minimum value D min For example, in the unactuated state, the fluid 18 may be distributed to a maximum extent laterally in a plane perpendicular to the direction of movement (e.g., the XY plane shown in FIG. 1A). When the fluid is distributed in this manner, the dimension 32 reaches a minimum value D min In the illustrated embodiment, the artificial muscle 14 is disposed directly on the base 12, and the dimension 32 is the maximum distance in the direction of movement 22 between the plane of the base 12 and the outer surface 20 of the expandable reservoir 16. As shown in FIG. 1C, when in the actuated state, the dimension 32 has a maximum value D max For example, the distribution of the fluid 18 is such that the dimension 32 has a maximum value D max 1C ) to be equal to D (e.g., by applying a potential difference between the electrodes to contract a region of the expandable reservoir 16, displacing fluid 18 and stretching the expanded region in the direction of movement 22). The actuated state shown in FIG. 1C may represent the designed maximum stretch of the expandable reservoir 16 in the direction of movement 22 (e.g., based on the material properties of the expandable reservoir 16, based on the minimum separation distance and lateral extent of the electrodes). As shown in FIG. 1B, when the artificial muscle drive unit 10 is between the unactuated state shown in FIG. 1A and the actuated state shown in FIG. 1C , dimension 32 is D min Bigger D max Smaller intermediate value D int In an embodiment, the partially actuated state shown in FIG. 1B represents a transient state of the artificial muscle 14 where fluid is moving to switch the artificial muscle 14 between an actuated state and an unactuated state. In an embodiment, the partially actuated state shown in FIG. 1B represents a static state of the artificial muscle 14 (e.g., dimension 32 is at an intermediate value D for a given period of time). int (It can be fixed in

[0018] In embodiments, the artificial muscle drive unit 10 is configured such that when in an unactuated state, the expansile reservoir 16 (or at least the portion of the expansile reservoir 16 that moves to transition the artificial muscle 14 between the actuated and unactuated states described herein) does not encounter an external force. It has been found that in transitioning an artificial muscle 14 to an actuated state, an external force can change the shape of the expansile reservoir 16 or impede movement of the expansile reservoir 16, thereby impeding redistribution of fluid 18 (e.g., in response to additional fluid being pumped into the expansile reservoir 16, or in response to an external stimulus such as a voltage manipulating the shape of the artificial muscle 14). Such impediment by an external force can cause the force output or displacement of the artificial muscle 14 to be reduced.

[0019] In view of the above, the artificial muscle drive unit 10 may include one or more load supports arranged to protect the expandable reservoir 16 from external forces. The structure and arrangement of the one or more load supports may vary depending on the structure of the artificial muscle drive unit 10, the configuration of the artificial muscles 14, and the particular force that the artificial muscles 14 are designed to impart to an external object. For example, referring to FIG. 1A, the artificial muscle drive unit 10 includes an actuation platform 28 that moves relative to the base 12 via the artificial muscles 14. FIG. 1A shows the actuation platform 28 in a rest position. In an embodiment, the actuation platform 28 extends perpendicular to the movement direction 22 in a rest position to protect the artificial muscles 14 when an object 26 is placed thereon.

[0020] In an embodiment, the object 26 may contact the actuation platform 28, whereby when the artificial muscles 14 apply a force to the actuation platform 28 (e.g., move the actuation platform 28 in the movement direction 22), the artificial muscle drive unit 10 applies a force to the object 26 via the actuation platform 28. To prevent the object 26 from loading the artificial muscles 14, the artificial muscle drive unit 10 includes load supports 24 and 30 disposed between the base 12 and the actuation platform 28. In an embodiment, the load supports 24 and 30 are fixedly attached to the base 12, and the actuation platform 28 moves relative to the load supports 24 and 30 in response to actuation of the artificial muscles 14. In some embodiments, the load supports 24 and 30 are fixedly attached to the actuation platform 28 such that the load supports 24 and 30 move in conjunction with the actuation platform 28 in response to actuation of the artificial muscles 14.

[0021] With continued reference to FIG. 1A , when in an unactuated state, the load supports 24 and 30 have a dimension (e.g., height) in the direction of movement 22 that is less than the minimum D of the dimension 32 of the artificial muscle 14. min And that's it. In an embodiment, the actuation platform 28 rests on the load supports 24 and 30 such that when the artificial muscle 14 is in an unactuated state, the actuation platform 28 and the artificial muscle 14 are separated in the direction of movement 22 by an offset distance 36. Separating the artificial muscle 14 and the actuation platform 28 in this manner by the offset distance 36 beneficially prevents the object 26 from applying a load to the artificial muscle 14 in the unactuated state, avoids impeding redistribution of the fluid 18, and allows the artificial muscle 14 to transition unhindered from the unactuated state to the actuated state. The extent of the offset distance 36 in the direction of movement 22 can vary depending on the implementation. For example, in an embodiment, the load supports 24 and 30 are designed to minimize the offset distance 36 (e.g., the offset distance 36 is set to a value greater than or equal to D min and D max(A small, non-zero value that is less than or equal to the difference between and.) In such an embodiment, it may be beneficial if the load supports 24 and 30 are constructed of a relatively rigid material (e.g., a metallic material, alloy, composite, plastic) since the offset distance 36 may be maintained within an appropriate tolerance.

[0022] In an embodiment, the offset distance 36 is set to D to provide adequate clearance to initiate fluid movement within the expandable reservoir 16 to transition the artificial muscle 14 from the unactuated state. min 1B, the expansile reservoir 16 first contacts the actuation platform 28 when the artificial muscle 14 is in a partially actuated state between the unactuated and actuated states shown in FIGS. 1A and 1C, respectively. The offset distance 36 (see FIG. 1A) beneficially allows the fluid 18 to redistribute within the expansile reservoir 16, causing the expansile reservoir 16 to partially extend in the direction of travel 22 to contact the actuation platform 28. As shown in FIG. 1C, when the artificial muscle 14 is fully actuated, the actuation platform 28 is moved in the direction of travel 22 a stroke distance D s Naturally, the stroke distance D s The magnitude of may vary depending on the design of the artificial muscle 14 and the magnitude of the load placed thereon (e.g., due to the mass of the object 26 and / or the actuation platform 28). Despite the offset distance 36 created by the load supports 24 and 30, the artificial muscle 14 achieves a greater stroke distance D with the load supports 24 and 30 than without them. s That is, when the object 26 exerts a force on the artificial muscle 14 in the unactuated state, the stroke distance D s The magnitude of the load applied by the mass 26 is reduced, decreasing the force applied to the mass 26. That is, the load supports 24 and 30 improve the performance of the artificial muscle 14 while holding other factors constant (e.g., the magnitude of the load applied by the mass 26).

[0023] It should be understood that the number and arrangement of load supports within the artificial muscle drive unit 10 may vary depending on the implementation. For example, in an embodiment, one or more load supports 24 and 30 may extend across the artificial muscle 14. For example, in an embodiment, the expandable reservoir 16 may have an opening therethrough (e.g., a substantially annular reservoir defined by an opening extending through the center), and one or more load supports 24 and 30 may extend through the opening. Such an implementation may be beneficial in that the load supports are located very close to the moving portion of the expandable reservoir 16, thereby allowing for tighter tolerances on the dimensions of the load supports 24 and 30. Also, embodiments are envisioned in which one or more load supports 24 and 30 are integrated into the artificial muscle 14. For example, in an embodiment, one or more load supports 24 and 30 may be located within the expandable reservoir 16, and the expandable reservoir 16 may extend in the direction of movement greater than the height of the one or more load supports 24 and 30.

[0024] Artificial muscle drive unit 10 may include any number of load supports (e.g., 1, 2, 3, 4, 5, 6, 7, 8, etc.), depending on the implementation. For example, in an embodiment, artificial muscle drive unit 10 includes only a single load support (e.g., one of load supports 24 and 30 may be omitted). Furthermore, load supports 24 and 30 can take a variety of different shapes. For example, in an embodiment, load supports 24 and 30 are integrated as a single component that extends around the entire circumference of artificial muscle 14. In an embodiment, load supports 24 and 30 are different shapes from one another.

[0025] 1A, 1B, and 1C, the load supports 24 and 30 are designed to provide structural support via an actuation platform 28 that extends substantially perpendicular to the direction of movement 22 (e.g., in the X direction shown in FIGS. 1A, 1B, and 1C). In an embodiment, the actuation platform 28 may be omitted, and the load supports 24 and 30 may directly prevent the expandable reservoir 16 from encountering external forces. In an embodiment, the actuation platform 28 and the load supports 24 and 30 are integrated as a single component (e.g., such that the artificial muscle 14 moves the load supports 24 and 30 and the actuation platform 28 in combination). In an embodiment, the load supports 24 and 30 and the base 12 are integrated as a single component.

[0026] Additionally, the directionality of support provided by load supports 24 and 30 may extend in directions other than those shown in Figures 1A, 1B, and 1C. For example, in embodiments, load supports 24 and 30 may be at different heights such that actuation platform 28 extends at an angle to base 12 rather than parallel to base 12 as shown. In embodiments, load supports 24 and 30 form a load-bearing surface that extends perpendicular to a particular direction of movement 22 of artificial muscle 14. In embodiments, load supports 24 and 30 simultaneously perform the functions described herein for multiple artificial muscles 14 (or a collection of multiple artificial muscles).

[0027] In an embodiment, the load supports 24 and 30 are removable from the artificial muscle drive unit 10. Such a configuration may advantageously facilitate replacement of the load supports 24 and 30 to adjust the operating parameters of the artificial muscle drive unit 10. For example, depending on the situation (e.g., the mass of the object 26), the load supports 24 and 30 may be removed and replaced with load supports of different heights. The actuation structures described herein may include multiple artificial muscle drive units 10 in multiple different configurations to achieve a desired actuation chain of artificial muscles 14. For example, as described herein with respect to Figures 9A and 9B, multiple artificial muscle drive units 10 may be stacked on top of each other in the movement direction 22 such that the displacements generated by the multiple artificial muscle drive units are combined.

[0028] 2, 3, 4A, and 4B, there is shown a schematic representation of an exemplary artificial muscle 100 that may be used as the artificial muscle 14 of the artificial muscle drive unit 10 described herein with reference to Figures 1A, 1B, and 1C. The artificial muscle 100 may also be displaced in artificial muscle stacks (e.g., artificial muscle stacks 201, 301, 301', etc., described herein with reference to Figures 6A-8) and layered actuation structures (e.g., layered actuation structure 500 described herein with reference to Figures 9A-13).

[0029] The artificial muscle 100 comprises a housing 110, an electrode pair 104 including a first electrode 106 and a second electrode 108 (see FIG. 4A ) secured to opposite sides of the housing 110, a first electrically insulating layer 111 secured to the first electrode 106, and a second electrically insulating layer 112 secured to the second electrode 108. In some embodiments, the housing 110 is a one-piece monolithic layer including a pair of opposing inner surfaces, such as a first inner surface 114 and a second inner surface 116, and a pair of opposing outer surfaces, such as a first outer surface 118 and a second outer surface 120. In some embodiments, the first inner surface 114 and the second inner surface 116 of the housing 110 are heat sealable. In other embodiments, the housing 110 may be a pair of separately manufactured membrane layers, such as a first membrane layer 122 and a second membrane layer 124. That is, the first membrane layer 122 includes the first inner surface 114 and the first outer surface 118 , and the second membrane layer 124 includes the second inner surface 116 and the second outer surface 120 .

[0030] It should be understood that although the embodiments described herein primarily refer to the housing 110 comprising the first and second membrane layers 122, 124 rather than a unitary housing, either configuration is contemplated. In some embodiments, the first and second membrane layers 122, 124 are generally of the same structure and composition. For example, in some embodiments, the first and second membrane layers 122, 124 are each comprised of biaxially oriented polypropylene.

[0031] The first electrode 106 and the second electrode 108 are each disposed between the first membrane layer 122 and the second membrane layer 124. In some embodiments, the first electrode 106 and the second electrode 108 are each an aluminum coated polyester such as Mylar®. It should be noted that one of the first electrode 106 and the second electrode 108 is a negatively charged electrode and the other of the first electrode 106 and the second electrode 108 is a positively charged electrode. For purposes discussed herein, either electrode 106, 108 can be positively charged as long as the other electrode 106, 108 of the artificial muscle 100 is negatively charged.

[0032] The first electrode 106 has a membrane-facing surface 126 and an opposite inner surface 128. The first electrode 106 is disposed against the first membrane layer 122, specifically against the first inner surface 114 of the first membrane layer 122. In addition, the first electrode 106 includes a first terminal 130 extending from the first electrode 106 through an edge of the first membrane layer 122, which can be connected to a power source to activate the first electrode 106. Specifically, as shown in FIG. 8, the terminals are connected directly or in series to a power source and a controller of the actuation system 400. Similarly, the second electrode 108 has a membrane-facing surface 148 and an opposite inner surface 150. The second electrode 108 is disposed against the second membrane layer 124, specifically against the second inner surface 116 of the second membrane layer 124. The second electrode 108 includes a second terminal 152 extending from the second electrode 108 through an edge of the second membrane layer 124, and the second terminal 152 can be connected to a power source and a controller of the actuation system 400 to actuate the second electrode 108.

[0033] The first electrode 106 includes two or more tab portions 132 and two or more bridge portions 140. Each bridge portion 140 is disposed between adjacent tab portions 132 and interconnects the adjacent tab portions 132. Each tab portion 132 has a first end 134 that extends radially from a central axis C of the first electrode 106 to a second end 136 opposite the tab portion 132, the second end 136 defining a portion of the circumference 138 of the first electrode 106. Each bridge portion 140 has a first end 142 that extends radially from the central axis C of the first electrode 106 to a second end 144 opposite the bridge portion 140 that defines another portion of the circumference 138 of the first electrode 106. Each tab portion 132 has a tab length L1, and each bridge portion 140 has a bridge length L2 that extends radially from the central axis C of the first electrode 106. Tab length L1 is the distance from first end 134 to second end 136 of tab portion 132, and bridge length L2 is the distance from first end 142 to second end 144 of bridge portion 140. Tab length L1 of each tab portion 132 is longer than bridge length L2 of each bridge portion 140. In some embodiments, bridge length L2 is 20% to 50% of tab length L1, such as 30% to 40% of tab length L1.

[0034] In some embodiments, the two or more tab portions 132 are arranged as one or more pairs of tab portions 132. Each pair of tab portions 132 includes two tab portions 132 arranged radially opposite each other. In some embodiments, the first electrode 106 may include only two tab portions 132 arranged on opposite sides or ends of the first electrode 106. In some embodiments, as shown in FIGS. 2 and 3, the first electrode 106 includes four tab portions 132 and four bridge portions 140 interconnecting adjacent tab portions 132. In this embodiment, the four tab portions 132 are arranged as two pairs of tab portions 132 radially opposite each other. Furthermore, as shown, the first terminal 130 extends from one second end 136 of the tab portion 132 and is integrally formed with the second end 136.

[0035] Similar to the first electrode 106, the second electrode 108 includes at least one pair of tab portions 154 and two or more bridge portions 162. Each bridge portion 162 is disposed between and interconnects adjacent tab portions 154. Each tab portion 154 has a first end 156 that extends radially from a central axis C of the second electrode 108 to a second end 158 opposite the tab portions 154, the second end 158 defining a portion of the circumference 160 of the second electrode 108. Because the first electrode 106 and the second electrode 108 are coaxial with each other, the central axis C of the first electrode 106 and the second electrode 108 are the same. Each bridge portion 162 has a first end 164 that extends radially from the central axis C of the second electrode to a second end 166 opposite the bridge portion 162 that defines another portion of the outer periphery 160 of the second electrode 108. Each tab portion 154 has a tab length L3, and each bridge portion 162 has a bridge length L4 that extends radially from the central axis C of the second electrode 108. The tab length L3 is the distance from the first end 156 to the second end 158 of the tab portion 154, and the bridge length L4 is the distance from the first end 164 to the second end 166 of the bridge portion 162. The tab length L3 is longer than the bridge length L4 of each bridge portion 162. In some embodiments, the bridge length L4 is 20% to 50% of the tab length L3, for example 30% to 40% of the tab length L3.

[0036] In some embodiments, the two or more tab portions 154 are arranged as one or more pairs of tab portions 154. Each pair of tab portions 154 includes two tab portions 154 arranged radially opposite each other. In some embodiments, the second electrode 108 may include only two tab portions 154 arranged on opposite sides or ends of the first electrode 106. In some embodiments, as shown in FIGS. 2 and 3, the second electrode 108 includes four tab portions 154 and four bridge portions 162 interconnecting adjacent tab portions 154. In this embodiment, the four tab portions 154 are arranged as two pairs of tab portions 154 radially opposite each other. Additionally, as shown, the second terminal 152 extends from one second end 158 of the tab portion 154 and is integrally formed with the second end 158.

[0037] 2-5B, at least one of the first electrode 106 and the second electrode 108 has a central opening formed therein between the first end 134 of the tab portion 132 and the first end 142 of the bridge portion 140. In FIGS. 4A and 4B, the first electrode 106 has a central opening 146. However, it should be understood that the first electrode 106 does not need to include the central opening 146 when the second electrode 108 has a central opening therein, as shown in FIGS. 5A and 5B. Alternatively, the second electrode 108 does not need to include a central opening when the first electrode 106 has a central opening 146 therein. Still referring to FIGS. 2-5B, the first electrical insulating layer 111 and the second electrical insulating layer 112 have shapes generally corresponding to the first electrode 106 and the second electrode 108, respectively. That is, the first and second electrically insulating layers 111, 112 have tab portions 170, 172 and bridge portions 174, 176, respectively, that correspond to similar portions of the first and second electrodes 106, 108. Additionally, the first and second electrically insulating layers 111, 112 each have a perimeter 178, 180 that corresponds to the perimeter 138 of the first electrode 106 and the perimeter 160 of the second electrode 108, respectively, when placed against the electrodes.

[0038] It should be understood that in some embodiments, the first and second electrically insulating layers 111, 112 generally comprise the same structure and composition. Thus, in some embodiments, the first and second electrically insulating layers 111, 112 each comprise an adhesive surface 182, 184 and an opposing non-sealing corresponding surface 186, 188. In some embodiments, the first and second electrically insulating layers 111, 112 are polymeric tapes adhered to the inner surface 128 of the first electrode 106 and the inner surface 150 of the second electrode 108, respectively.

[0039] 3-5B, the artificial muscle 100 is shown in an assembled state, with the first terminal 130 of the first electrode 106 and the second terminal 152 of the second electrode 108 extending around the periphery of the housing 110, i.e., through the first membrane layer 122 and the second membrane layer 124. As shown in FIG. 3, the second electrode 108 is layered on top of the first electrode 106, and therefore the first electrode 106, the first membrane layer 122, and the second membrane layer 124 are not shown. In the assembled state, the first electrode 106, the second electrode 108, the first electrical insulation layer 111, and the second electrical insulation layer 112 are sandwiched between the first membrane layer 122 and the second membrane layer 124. The first membrane layer 122 is partially sealed to the second membrane layer 124 in an area surrounding the perimeter 138 of the first electrode 106 and the perimeter 160 of the second electrode 108. In some embodiments, the first membrane layer 122 is heat sealed to the second membrane layer 124. Specifically, in some embodiments, the first membrane layer 122 is sealed to the second membrane layer 124 to define a seal 190 that surrounds the first electrode 106 and the second electrode 108. The first membrane layer 122 and the second membrane layer 124 can be sealed in any suitable manner, such as by use of an adhesive, heat sealing, or the like.

[0040] The first electrode 106, the second electrode 108, the first electrical insulation layer 111, and the second electrical insulation layer 112 provide a barrier that prevents the first film layer 122 from being sealed to the second film layer 124, and form an unsealed portion 192. The unsealed portion 192 of the housing 110 includes an electrode region 194 in which the electrode pair 104 is provided, and an expansion fluid region 196 surrounded by the electrode region 194. The expansion fluid region 196 of the artificial muscle 100 corresponds to the expansion reservoir 16 of the artificial muscle 14 in FIGS. 1A to 1C. The central openings 146, 168 of the first electrode 106 and the second electrode 108 form the expansion fluid region 196, and are arranged to be stacked on top of each other in the axial direction. Although not shown, the housing 110 may be cut to fit the shape of the electrode pair 104, and the size of the artificial muscle 100, i.e., the size of the sealed portion 190, may be reduced.

[0041] A dielectric fluid 198 is provided within the unsealed portion 192 and flows freely between the first electrode 106 and the second electrode 108. As used herein, a "dielectric" fluid is a medium or material that transmits electrical force without conduction and has low electrical conductivity. Some non-limiting examples of dielectric fluids include perfluoroalkanes, transformer oil, and deionized water. It should be understood that the dielectric fluid 198 can be injected into the unsealed portion 192 of the artificial muscle 100 using a needle or other suitable injection device.

[0042] 4A and 4B, the artificial muscle 100 is actuable between an unactuated state and an actuated state. In the unactuated state, the first electrode 106 and the second electrode 108 are partially spaced apart from one another near the central opening 146, 168 and the first ends 134, 156 of the tab portions 132, 154, as shown in FIG. 4A. The second ends 136, 158 of the tab portions 132, 154 are held in position relative to one another by the housing 110 being sealed to the perimeter 138 of the first electrode 106 and the perimeter 160 of the second electrode 108. In the actuated state, the first electrode 106 and the second electrode 108 are brought into contact and oriented parallel to one another, forcing the dielectric fluid 198 into the expansion fluid region 196, as shown in FIG. 4B. This causes the dielectric fluid 198 to flow through the central openings 146, 168 of the first electrode 106 and the second electrode 108, causing the expansion fluid region 196 to expand.

[0043] 4A, the artificial muscle 100 is shown in an unactuated state. The electrode pair 104 is disposed within an electrode region 194 of an unsealed portion 192 of the housing 110. The central opening 146 of the first electrode 106 and the central opening 168 of the second electrode 108 are coaxially aligned within an expansion fluid region 196. In the unactuated state, the first electrode 106 and the second electrode 108 are partially spaced apart and non-parallel to each other. The first membrane layer 122 is sealed to the second membrane layer 124 around the electrode pair 104 such that the second ends 136, 158 of the tab portions 132, 154 contact each other. This provides a dielectric fluid 198 between the first electrode 106 and the second electrode 108, separating the first ends 134, 156 of the tab portions 132, 154 adjacent the expansion fluid region 196. In other words, the distance between the first end 134 of the tab portion 132 of the first electrode 106 and the first end 156 of the tab portion 154 of the second electrode 108 is greater than the distance between the second end 136 of the tab portion 132 of the first electrode 106 and the second end 158 of the tab portion 154 of the second electrode 108. As a result, when activated, the electrode pair 104 zips toward the expansion fluid region 196. In some embodiments, the first electrode 106 and the second electrode 108 may be flexible. That is, as shown in FIG. 4A, the first electrode 106 and the second electrode 108 are convex such that they are spaced apart from each other near the central openings 146, 168 even though the second ends 136, 158 of the tab portions 132, 154 remain close to each other. In the unactuated state, the expansion fluid region 196 has a first height H1.

[0044] When actuated, the first electrode 106 and the second electrode 108 fasten toward each other from the second ends 144, 158 of the tab portions 132, 154, as shown in FIG. 4B, thereby forcing the dielectric fluid 198 into the expansion fluid region 196. As shown, in the actuated state, the first electrode 106 and the second electrode 108 are parallel to each other. In the actuated state, the dielectric fluid 198 flows into the expansion fluid region 196, causing it to expand. In this way, the first membrane layer 122 and the second membrane layer 124 stretch in opposite directions. In the actuated state, the expansion fluid region 196 has a second height H2 that is greater than the first height H1 of the expansion fluid region 196 in the non-actuated state. Although not shown, the electrode pair 104 may be partially actuated to be between the non-actuated state and the actuated state. This allows the expansion fluid region 196 to be partially expanded and adjusted as needed.

[0045] A voltage is applied by a power source (such as power source 48 of FIG. 13) to move the first electrode 106 and the second electrode 108 toward each other. In some embodiments, a voltage of up to 10 kV can be provided by the power source to induce an electric field through the dielectric fluid 198. This results in an attractive force between the first electrode 106 and the second electrode 108, forcing the dielectric fluid 198 into the expansion fluid region 196. Pressure from the dielectric fluid 198 in the expansion fluid region 196 causes the first membrane layer 122 and the first electrically insulating layer 111 to deform in a first axial direction along the central axis C of the first electrode 106, and the second membrane layer 124 and the second electrically insulating layer 112 to deform in an opposite second axial direction along the central axis C of the second electrode 108. When the voltage supplied to the first electrode 106 and the second electrode 108 is stopped, the first electrode 106 and the second electrode 108 return to their initial non-parallel positions in the unactuated state. In operation, a voltage can be applied to one or more of the artificial muscles 100 in the artificial muscle stacks 201, 301, 301' of Figures 6A-8 and the layered actuation structure 500 (Figures 9A-11) to collectively and / or selectively actuate the artificial muscles 100 in the artificial muscle stacks 201, 301, 301' and the layered actuation structure 500.

[0046] This embodiment of the artificial muscle 100 disclosed herein, specifically the tab portions 132, 154 and the bridge portions 174, 176 that interconnect the tab portions 132, 154, offers several improvements over actuators that do not include the tab portions 132, 154, such as the Hydraulically Amplified Self-Healing Electrostatic (HASEL) actuators described in the paper entitled "Hydraulically amplified self-healing electrostatic actuators with muscle-like performance" by E. Acome, S.K. Mitchell, T.G. Morrissey, M.B. Emmett, C. Benjamin, M. King, M. Radakovitz, and C. Keplinger (Science, January 5, 2018: Vol. 359, Issue 6371, pp. 61-65). Various embodiments of the artificial muscle 100 that include two pairs of tab portions 132, 154 on each of the first electrode 106 and the second electrode 108 reduce the overall mass and thickness of the artificial muscle 100, reduce the amount of voltage required during actuation, and reduce the total volume of the artificial muscle 101, without reducing the amount of force generated after actuation, compared to known HASEL actuators that include toroidal electrodes with radially uniform widths. More specifically, the tab portions 132, 154 of the artificial muscle 100 provide a fastener front that provides increased actuation force by providing localized and uniform hydraulic actuation of the artificial muscle 100, compared to HASEL actuators that include toroidal electrodes. Specifically, one pair of tab portions 132, 154 provides twice the actuator force per unit volume, and two pairs of tab portions 132, 154 provide four times the actuator force per unit volume, compared to toroidal HASEL actuators. The bridge portions 174, 176 interconnecting the tab portions 132, 154 also limit buckling of the tab portions 132, 154 by maintaining a distance between adjacent tab portions 132, 154 during actuation. Because the bridge portions 174, 176 are integrally formed with the tab portions 132, 154, the bridge portions 174, 176 also prevent leakage between the tab portions 132, 154 by eliminating attachment points that increase the risk of rupture.

[0047] In operation, actuating the artificial muscle 100 by supplying and applying a voltage to the electrode pairs 104 of the artificial muscle 100 causes the expansive fluid region 196 to expand and expand beyond the cubic centimeters (cm) of the actuator volume. 3 ) produces a force of 3 Newton millimeters (N.mm) or more per 1 cm 3 More than 4N.mm per cm 3 5N.mm or more per 1cm 3 6N.mm or more per 1cm 3 7N.mm or more per 1cm 3 Such a force may be 8 N.mm or more per second. Providing a voltage may include generating a voltage, for example, in embodiments where the power source 48 (FIGS. 9A-13) is a battery, converting a voltage, for example, in embodiments where the power source 48 (FIGS. 9A-13) is a power adapter, or any other known or yet to be developed technique for arranging for application of a voltage. In one example, when the artificial muscle 100 is actuated by a voltage of 9.5 kilovolts (kV), the artificial muscle 100 provides a force of 5 N. In another example, when the artificial muscle 100 is actuated by a voltage of 10 kV, the artificial muscle 100 provides a 440% tension under a load of 500 grams.

[0048] Additionally, the size of the first electrode 106 and the second electrode 108 is proportional to the amount of displacement of the dielectric fluid 198. Thus, if a greater displacement is desired within the expansion fluid region 196, the size of the electrode pair 104 is increased in proportion to the size of the expansion fluid region 196. It should be understood that the size of the expansion fluid region 196 is defined by the central openings 146, 168 in the first electrode 106 and the second electrode 108. That is, the degree of displacement within the expansion fluid region 196 may alternatively or additionally be controlled by increasing or decreasing the size of the central openings 146, 168.

[0049] As shown in Figures 5A and 5B, another embodiment of an artificial muscle 100' is illustrated. The artificial muscle 100' is substantially similar to the artificial muscle 100. As such, similar structures are indicated with similar reference numbers. However, as shown, the first electrode 106 does not include a central opening. That is, only the second electrode 108 includes a central opening 168 formed therein. As shown in Figure 5A, the artificial muscle 100' is in an unactuated state in which the first electrode 106 is flat and the second electrode 108 is convex relative to the first electrode 106. In the unactuated state, the expansion fluid region 196 has a first height H3. In the actuated state, as shown in Figure 5B, the expansion fluid region 196 has a second height H4, which is greater than the first height H3. It should be appreciated that by providing the central opening 168 only in the second electrode 108, rather than both the first electrode 106 and the second electrode 108, all of the deformations can be formed on one side of the artificial muscle 100'. Additionally, because all of the deformations are formed on only one side of the artificial muscle 100', the second height H4 of the expansion fluid region 196 of the artificial muscle 100' extends further from the longitudinal axis perpendicular to the central axis C of the artificial muscle 100' than the second height H2 of the expansion fluid region 196 of the artificial muscle 100, all other dimensions, orientation, and volume of dielectric fluid being the same.

[0050] 6A-8, artificial muscle stacks 201, 301, 301' are shown. In FIGS. 6A-8, each of the artificial muscle stacks 201, 301, 301' comprises a plurality of artificial muscle layers 210, 310, each of the plurality of artificial muscle layers 210, 310 comprises one or more artificial muscles 100. In some embodiments, the plurality of artificial muscle layers may alternatively or additionally comprise the artificial muscle 100' of FIGS. 5A-5B. In operation, the artificial muscle stacks 201, 301, 301' generate a greater actuation force than a single artificial muscle 100. FIGS. 6A-8 show several different stack configurations that can be used to increase the actuation force.

[0051] The artificial muscle stack 201 of FIGS. 6A-6C includes multiple artificial muscle layers 210 arranged in coaxial alignment such that the expansion fluid regions 196 of the individual artificial muscles 100 in each individual artificial muscle layer 210 are coaxially aligned with the individual artificial muscles 100 in each other individual artificial muscle layer 210. As shown in the side views of FIGS. 6B and 6C, the artificial muscle stack 201 includes three artificial muscle layers 210A-210C. It should be understood that any number of artificial muscle layers 210 is contemplated. FIG. 6B illustrates the artificial muscle stack 201 in an unactuated state, and FIG. 6C illustrates the artificial muscle stack 201 in an actuated state. In each layer of the artificial muscle stack 201, the individual artificial muscles 100 do not overlap. Additionally, the artificial muscles 100 of adjacent artificial muscle layers 210 may be glued or sewn together to stabilize their relative positions. 6A-6B may collectively generate an actuation force, but the attachment area is large due to the coaxial alignment of the individual artificial muscles 100 in each artificial muscle layer 210. To reduce the attachment area due to the arrangement of artificial muscles, the artificial muscle stack 301 shown in Figures 7A-7E may be implemented.

[0052] The artificial muscle stack 301 of Figures 7A-7E includes multiple artificial muscle layers 310 arranged in an alternating offset fashion. The artificial muscle stack 301 includes four artificial muscle layers 310: a first artificial muscle layer 310A, a second artificial muscle layer 310B, a third artificial muscle layer 310C, and a fourth artificial muscle layer 310D. Figure 7A is a top view of the artificial muscle stack 301, and Figures 7B-7E are side views of the artificial muscle stack 301. Figures 7B and 7C show side views of the artificial muscle stack 301 along line 6B-6B in the unactuated state (Figure 7B) and in the actuated state (Figure 7C). Figures 7D and 7E show side views of the artificial muscle stack 301 along line 6D-6D in the unactuated state (Figure 7D) and in the actuated state (Figure 7E). Line 6B-6B is orthogonal to line 7D-7D, and thus Figures 7B and 7C show a different side of artificial muscle stack 301 than Figures 7D and 7E, and the side shown in Figures 7B and 7C is orthogonal to the side shown in Figures 7D and 7E.

[0053] Each artificial muscle layer 310 comprises one or more artificial muscles 100, e.g., a plurality of artificial muscles 100. For example, in FIG. 7A, the first artificial muscle 100A is an example of an artificial muscle 100 in the artificial muscle stack 301. It should be understood that embodiments are contemplated in which a portion of the artificial muscle layers 310 in the artificial muscle stack 301 comprises a single artificial muscle 100. Furthermore, the artificial muscles 100 in adjacent artificial muscle layers 310 may be glued or sewn together to stabilize their positional relationship. In the alternating offset arrangement of the artificial muscle stack 301 shown in FIGS. 7A-7E, the multiple artificial muscle layers 310 are arranged such that each expansion fluid region 196 of the housing 110 of the one or more artificial muscles 100 in each artificial muscle layer 310 overlaps at least one tab portion 132, 154 of the one or more artificial muscles 100 in the adjacent artificial muscle layer 310. In other words, each expansion fluid region 196 of the housing 110 of one or more artificial muscles 100 in each artificial muscle layer 310 overlaps with the electrode region 194 of the housing 110 of one or more artificial muscles 100 in an adjacent artificial muscle layer 310. In some embodiments, an individual tab portion 132, 154 of an artificial muscle 100 may overlap an expansion fluid region 196 of an artificial muscle 100 in an adjacent artificial muscle layer 310, and the second ends 136, 158 of the individual tab portions 132, 154 terminate at or near the central axis C of the expansion fluid region 196 of the artificial muscle 100 in the adjacent muscle layer 310. Thus, a portion of the expansion fluid region 196 may be overlapped by two tab portions 132, 154 from different artificial muscles 100 on one or both sides of the expansion fluid region 196. Although the tabbed portion 154 of the second electrode 108 of the electrode pair 104 is shown in FIG. 7A, it should be understood that the electrode pair 104 also includes a first electrode 106 having a tabbed portion 132 .

[0054] To explain the alternating offset arrangement of the artificial muscle stacks 301 in Figures 7A-7E, the relative line widths of the artificial muscles 100 in each artificial muscle layer 310 are used to explain the relative spatial positional relationship of each artificial muscle layer 310. For example, in Figure 7A, the first artificial muscle layer 310A is the top layer, and therefore the artificial muscles 100 in the first artificial muscle layer 310A are depicted with the widest line width among the multiple artificial muscle layers 310. Similarly, in Figure 7A, the fourth artificial muscle layer 310D is the bottom layer, and therefore the artificial muscles 100 in the fourth artificial muscle layer 310D are depicted with the thinnest line width among the multiple artificial muscle layers 310.

[0055] In an alternating offset arrangement of the artificial muscle stack 301, adjacent artificial muscle layers 310 of the artificial muscle stack 301 are offset from one another along one or more tab axes, such as a first tab axis 338 or a second tab axis 340. Each tab axis extends from a central axis C of the expandable fluid region 196 of an individual artificial muscle 100 of the plurality of artificial muscle layers 310 to an end (i.e., a second end 136, 158) of at least one tab portion 132, 154 of an individual artificial muscle 100 of the plurality of artificial muscle layers 310. The embodiment of the artificial muscles 100 of the artificial muscle stack 301 shown in FIGS. 7A-7E includes four tab portions 132, 154 each arranged in a diametrically opposed pair with respect to one another, with the first tab axis 338 perpendicular to the second tab axis 340. It should be understood that while the artificial muscles 100 of the artificial muscle stack 301 include four tab portions 132, 154 (i.e., each electrode of the electrode pair 104 of each artificial muscle 100 includes four tab portions 132, 154), embodiments of the artificial muscles 100 including more or less than four tab portions 132 are contemplated. These embodiments may include more than two tab shafts, such as, for example, embodiments having three tab portions per electrode, five tab portions per electrode, or six tab portions per electrode. Alternatively, they may include only a single tab shaft, such as an embodiment including a pair of tab portions diametrically opposed to one another. Additionally, it should be understood that other artificial muscle designs, such as, for example, triangular or rectangular artificial muscles, are contemplated, as are embodiments in which the alternating offset arrangements.

[0056] 7A-7E, embodiments of an artificial muscle stack 301 with at least three artificial muscle layers 310 include at least one internal artificial muscle layer, which is an artificial muscle layer 310 adjacent to two other artificial muscle layers 310. In these embodiments, each internal artificial muscle layer is offset from the first adjacent artificial muscle layer along a first tab axis 338 and offset from the second adjacent artificial muscle layer along a second tab axis 340. This multi-axis offset is depicted in the side views of FIGS. 7B-7E by a lateral offset indicating the offset along one tab axis and a relative line width indicating the offset along the other tab axis. In FIGS. 7B and 7C, the offset between the artificial muscle layers 310 along the second tab axis 340 is indicated by the lateral offset, and the offset between adjacent artificial muscle layers 310 along the first tab axis 338 is indicated by the relative line width. In particular, the wider line widths in Figures 7B and 7C show the artificial muscle layer 310 displaced to the front (i.e., towards the page) along the first tab axis 338, and the narrower line widths in Figures 7B and 7C show the artificial muscle layer 310 displaced to the back (i.e., towards the page) along the first tab axis 338. In Figures 7D and 7E, the offset between the artificial muscle layers 310 along the first tab axis 338 is shown by the lateral offset, and the offset between adjacent artificial muscle layers 310 along the second tab axis 340 is shown by the relative line widths. In particular, the wider line widths in Figures 7D and 7E show the artificial muscle layer 310 displaced to the front (i.e., towards the page) along the second tab axis 340, and the narrower line widths in Figures 6D and 6E show the artificial muscle layer 310 displaced to the back (i.e., towards the page) along the second tab axis 340.

[0057] 7A-7E, second artificial muscle layer 310B and third artificial muscle layer 310C are inner artificial muscle layers. Second artificial muscle layer 310B is offset from first artificial muscle layer 310A along first tab axis 338 and from third artificial muscle layer 310C along second tab axis 340. Third artificial muscle layer 310C is offset from second artificial muscle layer 310B along second tab axis 340 and from fourth artificial muscle layer 310D along first tab axis 338. In artificial muscle stack 301 with a larger number of artificial muscle layers 310, this pattern can be repeated to allow for a closely packed stacked arrangement of artificial muscle layers.

[0058] 7A-7E, the alternating offset arrangement of the artificial muscle stack 301 allows a greater number of artificial muscles 100 to be placed within a particular mounting area, as compared to the artificial muscle stack 201 of FIGS. 5A-5C, due to the overlap of the tab portions 132, 154 and expansion fluid regions 196 in adjacent artificial muscle layers 310. In effect, the artificial muscle stack 301 maximizes the number of artificial muscles 100 that can be placed within a particular mounting area, both laterally (i.e., along the first and second tab axes 338, 340) and in depth, maximizing the aggregate actuation force per unit volume of the artificial muscle stack 301. As each artificial muscle 100 is actuated, the tab portions 132, 154 of the electrode pairs 104 are brought closer together (e.g., flattened) and the expansion fluid region 196 is stretched. Because the tabs 132, 154 are flattened, the expansion fluid regions 196 of the artificial muscles 100 can be located above and / or below the tabs of the adjacent artificial muscle layer 310. This allows a larger number of artificial muscles to be grouped together to form a cohesive block (i.e., the artificial muscle stack 301) and work in concert. In effect, the artificial muscle stack 301 is designed so that the artificial muscles 100 in each artificial muscle layer 310 can additively exert their collective force. In contrast, in the coaxial alignment of the artificial muscle stack 201 in FIG. 6A, the expansion fluid regions 196 of each artificial muscle layer 210 overlap, limiting the additive force that each artificial muscle layer 210 can generate.

[0059] Next, referring to FIG. 8, an artificial muscle stack 301' is depicted. The artificial muscle stack 301' comprises the artificial muscle stack 301 of FIGS. 7A-7E with the addition of a peripheral artificial muscle 315. The peripheral artificial muscle 315 has the same structure as the artificial muscle 100, but has fewer tab portions 132, 154 than the artificial muscle 100 of the artificial muscle stack 301', as shown in the first peripheral artificial muscle 315A. As shown in FIG. 8, the artificial muscle 100 of the artificial muscle stack 301' comprises four tab portions 132, 154, and the peripheral artificial muscle 315 comprises either two or three tab portions 132, 154. In particular, the peripheral artificial muscle 315 may comprise a peripheral peripheral artificial muscle 316 and a corner peripheral artificial muscle 318. The edge perimeter artificial muscles 316 extend along a single side of the artificial muscle stack 301, and the corner perimeter artificial muscles 318 are positioned at the corners of the artificial muscle stack 301, with one tab portion of the corner perimeter artificial muscles 318 extending along one side of the artificial muscle stack 301 and another tab of the corner perimeter artificial muscles 318 extending along another side of the artificial muscle stack 301.

[0060] As shown in Figures 7A-7E, the alternating offset arrangement of the multiple artificial muscle layers 310 of the artificial muscle stack 301 creates asymmetry at the edges of the artificial muscle stack 301. That is, the alternating offset arrangement can cause the artificial muscle layers 310 to terminate at different locations in the lateral direction, creating gaps at the edges of the artificial muscle stack 301. As shown in Figure 8, peripheral artificial muscles 315 can be used to fill these edge gaps so that each artificial muscle layer 310 of the artificial muscle stack 301' shares a border in the lateral direction. In some embodiments, to uniform the symmetry along the edges of the artificial muscle stack 301 and add additive actuation forces to the artificial muscle stack 301 without expanding the overall mounting area, each artificial muscle layer 310 includes peripheral artificial muscles 315 consisting of, for example, a combination of edge peripheral artificial muscles 316 and corner peripheral artificial muscles 318.

[0061] 9A and 9B, a layered actuation structure 500 is shown in schematic form. FIG. 9A shows the layered actuation structure 500 in a non-actuated state. FIG. 9B shows the layered actuation structure 500 in an actuated state. The layered actuation structure 500 includes one or more actuation platforms 502 interleaved with one or more mounting platforms 506 to form one or more platform pairs 510. Each platform pair 510 includes a mounting platform 506 and an actuation platform 502 to form an actuation cavity 512 therebetween. The one or more actuation platforms 502 each include a cavity-facing surface 504. Similarly, the one or more mounting platforms 506 each include a cavity-facing surface 508. In each platform pair 510, the cavity-facing surface 504 of each actuation platform 502 faces the cavity-facing surface 508 of each mounting platform 506. In some embodiments, actuation platform 502 and mounting platform 506 each have a thickness between 1 / 4 inch and 1 / 32 inch, such as 1 / 4 inch, 1 / 8 inch, 1 / 10 inch, 1 / 12 inch, 1 / 16 inch, 1 / 20 inch, 1 / 24 inch, 1 / 28 inch, 1 / 32 inch, or any range containing any two of these values ​​as endpoints.

[0062] 9A and 9B, each of the platform pairs 510 is spaced at least a cavity displacement distance 530 from at least one adjacent platform pair 510 to provide clearance for relative movement of the one or more actuation platforms 502 relative to the one or more mounting platforms 506 in a movement direction (e.g., the Y direction depicted in FIGS. 9A and 9B). Additionally, one or more artificial muscles 100 are disposed within each actuation cavity 512 such that actuation of the one or more artificial muscles 100, i.e., expansion of the expansion fluid region 196, exerts pressure on the one or more actuation platforms 502, causing translational movement of the one or more actuation platforms 502. Although an artificial muscle 100 is shown in FIGS. 9A and 9B, it should be understood that the layered actuation structure 500 may include any embodiment of an artificial muscle described herein. In some embodiments, a single artificial muscle 100 is disposed in some or all of the actuation cavities 512. In other embodiments, multiple artificial muscles 100 are disposed in some or all of the actuation cavities 512. Furthermore, when multiple artificial muscles 100 are arranged in an actuation cavity, the multiple artificial muscles 100 are arranged as an artificial muscle stack 301 having multiple artificial muscle layers arranged in an alternating offset manner, as described above with reference to Figures 7A to 8.

[0063] 9A and 9B, the actuation structure 500 includes one or more load supports 560. In the illustrated embodiment, the actuation structure 500 includes a plurality of load supports 560, with one or more of the plurality of load supports 560 disposed in one of the actuation cavities 512. In an embodiment, the plurality of load supports 560 define a minimum separation distance between each pair of cavity-facing surfaces 504 and 508 that define each actuation cavity 512. The minimum separation distance may extend in a direction of movement in which the plurality of artificial muscles 100 are designed to expand and move across the actuation surface 540. In an embodiment, the actuation surface 540 may encounter a load from an external source (e.g., an object may be placed on the actuation surface 540). The load supports 560 beneficially prevent the actuation platform 502 from compressing the artificial muscles 100 of the actuation structure 500 when the artificial muscles 100 are in an unactuated state.

[0064] In an embodiment, the height of one load support 560 (e.g., in the Y direction shown in FIGS. 9A and 9B ) is determined based on the height of the artificial muscle structure disposed in the actuation cavity 512 of the load support 560. In an embodiment, the height of the multiple load supports 560 is at least as large as the height of the artificial muscle structure disposed in the actuation cavity 512 that includes the multiple load supports (e.g., the combined height when multiple artificial muscles 100 are stacked in the direction of movement). In an embodiment where the actuation cavities 512 include different numbers and arrangements of artificial muscles 100, for example, the height of the multiple load supports 560 may vary across the actuation structure 500. By way of example, if one actuation cavity 512 includes a single artificial muscle 100, the height of the load support 560 disposed therein may be smaller than the load support disposed in another one of the actuation cavities 512 with the artificial muscle stack 301′. Embodiments where the multiple load supports 560 are of the same structure (e.g., height) are also envisioned, regardless of the structure of the artificial muscle disposed in each of the actuation cavities.

[0065] 9A , when the plurality of artificial muscles 100 is in an unactuated state as described herein, the plurality of load supports 560 maintain a gap between the cavity-facing surfaces 504 and 508 and the exterior surface of the plurality of artificial muscles 100. As described herein, such a gap promotes fluid movement within each of the plurality of artificial muscles 100 and promotes the transition from an unactuated state to a partially actuated state to an actuated state. In embodiments, such a gap facilitates the plurality of artificial muscles 100 having a greater extension capability when the actuation structure 500 encounters an external load (e.g., when an object is placed on the actuation surface 540) than embodiments that do not include the plurality of load supports 560.

[0066] 9B , when the plurality of artificial muscles 100 are in an actuated state described herein, the outer surfaces of the plurality of artificial muscles 100 contact the cavity-facing surfaces 504 and 508 and apply a force in the direction of movement. In an embodiment, the plurality of mounting platforms 506 are fixed (e.g., by support arms 524 coupled to a base) and the plurality of actuating platforms 502 are movable in the direction of movement (e.g., by being coupled to actuating arms 522 that are movable relative to a base) such that the force from the plurality of artificial muscles 100 lifts each actuating platform 502 on top of each of the plurality of load supports 560 a cavity displacement distance 530 in the direction of movement.

[0067] 9A and 9B , in an embodiment, the multiple load supports 560 are disposed inside each of the actuation cavities 512 (e.g., between the support arm 524 and the actuation arm 522). In an embodiment, the multiple load supports 560 are disposed outside the multiple artificial muscles 100 (e.g., the multiple load supports 560 do not overlap the multiple artificial muscles 100 in the movement direction). In an embodiment, the multiple load supports 560 are disposed in a peripheral region of each of the actuation cavities 512, and the multiple artificial muscles 100 are disposed in a central region of each of the actuation cavities 512.

[0068] In an embodiment, the load supports 560 are disposed outside the actuation cavity 512. For example, as described herein with respect to FIG. 11, in an embodiment, the mounting platform 506 and the actuation platform 502 may include extension tabs (such as extension tabs 570 shown in FIG. 11) that extend from the actuation cavity 512 in a direction perpendicular to the direction of movement (e.g., the X direction shown in FIG. 9B) outwardly of the perimeter, and the load supports 560 may extend between the extension tabs. Such an implementation may facilitate compactness of the actuation structure 500 by limiting the lateral extent of the bodies of the actuation platform 502 and the mounting platform 506 to the size of the configuration of artificial muscles disposed therein. Embodiments are also envisioned in which the load supports 560 extend through the configuration of artificial muscles 100 disposed in one or more actuation cavities 512, or in which the load supports 560 are integrated into the structure of the artificial muscles 100.

[0069] 9A and 9B, the one or more actuation platforms 502 and the one or more mounting platforms 506 each include one or more ridges 550 that extend into the one or more actuation cavities 512. In particular, the ridges 550 extend outward from the cavity-facing surface 504 of the actuation platform 502 and the cavity-facing surface 508 of the mounting platform 506. The one or more ridges 550 are sized and positioned to overlap at least one electrode region 194 of one or more artificial muscles 100 disposed in the actuation cavity 512. During operation, as the expandable fluid region 196 of the artificial muscle 100 expands and presses against the cavity-facing surfaces 504, 508 of the actuation platform 502 and the mounting platform 506, the contracted electrode region 194 presses against the ridges 550. In some embodiments, the ridges 550 are positioned to correspond to the alternating offset arrangement of the artificial muscle stacks 301. That is, the one or more ridges 550 are positioned such that each ridge 550 is aligned with at least one tab portion 132 that is disposed in the electrode region 194 of at least one artificial muscle 100. In some embodiments, the multiple load supports 560 may also maintain a gap between the one or more ridges 550 and the outer surface of the multiple artificial muscles 100.

[0070] 9A-11, in an embodiment, the layered actuation structure 500 further includes one or more platform linking arms 520 that link the platform pairs 510 to one another. The platform linking arms 520 maintain the lateral alignment (i.e., alignment in the X and Z directions) of the platform pairs 510, maintain the spacing between the mounting platforms 506 of adjacent platform pairs 510 in the direction of movement (i.e., in the Y direction), and allow translational movement in the direction of movement of the actuation platforms 502 of each platform pair 510. As shown in FIGS. 10-11, in an embodiment, the one or more platform linking arms 520 include a plurality of platform linking arms 520, each of which includes at least one actuation arm 522 coupled to one or more actuation platforms 502 and at least one support arm 524 coupled to one or more mounting platforms 506. In particular, the actuation arm 522 is fixedly coupled to each actuation platform 502 and translatably coupled to each mounting platform 506, and the support arm 524 is fixedly coupled to each mounting platform 506 and translatably coupled to each actuation platform 502. The translational coupling may be a slidable coupling. For example, as shown in FIG. 10, the platform linkage arm 520 may include a number of notches 525. The number of notches 525 provide locations for connectors 526, such as screws, for connecting the platform linkage arm 520 to the actuation platform 502 and mounting platform 506, and also allow for movement of the actuation platform 502 during operation of the layered actuation structure 500 while maintaining a connection between the platform linkage arm 520 and the platform pair 510. In some embodiments, the actuation platform 502 and mounting platform 506 may comprise a screw block portion that is thicker than the remainder of each platform 502, 506 and provides a connection location for the connectors 526.

[0071] As shown in Figures 10 and 11, in some embodiments, the layered actuation structure 500 comprises a plurality of support arms 524 and a plurality of actuation arms 522. For example, the layered actuation structure 500 may comprise a first support arm 524A, a second support arm 524B, a first actuation arm 522A, and a second actuation arm 522B. The first and second support arms 524A, 524B are each coupled to one or more mounting platforms 506, and the first and second actuation arms 522A, 522B are each coupled to one or more actuation platforms 502. The first support arm 524A and the second support arm 524B are coupled to the one or more mounting platforms 506 at opposing locations along a peripheral edge 507 of the one or more mounting platforms 506. The first actuation arm 522A and the second actuation arm 522B are coupled to the one or more actuation platforms 502 at opposing locations along a peripheral edge 503 of the one or more actuation platforms 502. Further, the first and second support arms 524A, 524B are positioned relative to the first and second actuating arms 522A, 522B such that an axis extending between the first support arm 524A and the second support arm 524B is perpendicular to an axis extending between the first actuating arm 520A and the second actuating arm 520B.

[0072] 9A-11, the layered actuation structure 500 further comprises an actuation surface 540 configured to impart cavity forces (e.g., individual cavity forces or multi-cavity forces) generated by translational movement of one or more actuation platforms 502. In some embodiments, the actuation surface 540 is a surface of an actuation block 542, which may be coupled to at least one actuation arm 522, as shown in FIGS. 9A and 9B, or may be coupled to an actuation platform 502 (e.g., an uppermost or distal actuation platform 502), as shown in FIG. 10. In other embodiments, the actuation surface 540 may be a surface of the actuation platform 502 itself, as shown in FIG.

[0073] During operation, as one or more artificial muscles 100 apply pressure to the cavity-facing surfaces 504 of one or more actuation platforms 502, the actuation platform 502 translates in a direction of movement relative to the mounting platform 506. That is, actuation of one or more artificial muscles 100 disposed in at least one actuation cavity 512 causes translational movement of the one or more actuation platforms 502 along a cavity displacement distance 530. In embodiments in which artificial muscle stacks are disposed in the actuation cavities 512, the cavity displacement distance can be increased by increasing the number of layers of artificial muscles 100, but the cavity displacement distance 530 cannot be increased by increasing the number of platform pairs 510. However, translational movement of each individual actuation platform 502 generates individual cavity forces, which are additive forces.

[0074] That is, when the layered actuation structure 500 includes multiple actuation cavities 512, such as the embodiment shown in Figures 9A and 9B, the individual actuation platforms generate individual cavity forces and the layered actuation structure generates multi-cavity forces. The multi-cavity forces are additive of the individual cavity forces. In some embodiments, the multi-cavity forces are 10 Newtons (N) or greater, e.g., 15N or greater, 20N or greater, 25N or greater, 30N or greater, 35N or greater, 40N or greater, 45N or greater, 50N or greater, 55N or greater, 60N or greater, 65N or greater, 70N or greater, 75N or greater, 80N or greater, 85N or greater, 90N or greater, 95N or greater, 100N or greater, 105N or greater, 110N or greater, 115N or greater, 120N or greater, or any range including any two of these values. Indeed, embodiments are contemplated in which a layered actuation structure 500 with a lateral mounting area of ​​5 cm x 5 cm is capable of generating a multi-cavity force of 80 N.

[0075] In the embodiment shown in FIG. 10, a plurality of load supports 560 are disposed inside one or more platform linkage arms 520 in each actuation cavity 512. In the depicted embodiment, each one of the actuation cavities 512 includes eight load supports 560 disposed therein (e.g., on either side of the one or more platform linkage arms 520 to provide robust and symmetrical support). It should be understood that alternative embodiments having a different number of load supports per actuation cavity are contemplated and are within the scope of the present disclosure. For example, in an embodiment, each actuation cavity 512 includes a single load support 560 disposed therein, and the load support 560 may include a frame-like member that extends around the entire circumference of each actuation cavity 512. Embodiments in which a plurality of actuation cavities 512 include a different number of load supports 560 having different shapes and sizes are also envisioned.

[0076] 11, the load supports 560 are disposed on the exterior of the actuation arm 522 and the support arm 524. The mounting platforms 506 and the actuation platforms 502 each include a plurality of extension tabs 570 extending laterally outward from their bodies, such that each of the actuation cavities 512 has one or more sets of extension tabs 570 associated therewith. The load supports 560 may be disposed locally between the extension tabs 570 associated with the mounting platforms 506 and the actuation platforms 502 of each actuation cavity 512. Such a structure advantageously facilitates the load supports 560 being laterally offset from the bodies of the mounting platforms 506 and the actuation platforms 502. The use of the extension tabs 570 allows more artificial muscles to be disposed within each actuation cavity 512, advantageously increasing the overall force density per unit weight of the actuation structure 500.

[0077] 12, a plot 1200 of force versus displacement is shown for one of the artificial muscles 100 described herein. The plot 1200 depicts the magnitude of force imparted by one of the artificial muscles 100 versus displacement with and without a load support. In the absence of a load support, the artificial muscle 100 encountered a force from an external force in an unactuated state as described herein. As shown, the load support increases the force per unit displacement of the artificial muscle 100 (for a particular displacement, the force magnitude is improved by over 30%). This example demonstrates the effectiveness of the load supports described herein for improving actuation performance.

[0078] 13, an actuation system 400 can be provided for actuating individual artificial muscles 100 of a layered actuation structure 500 or artificial muscles 14 of an artificial muscle drive unit 10 described herein with reference to Figures 1A, 1B, and 1C. The actuation system 400 can include a controller 50, an operating device 46, a power source 48, a display 42, network interface hardware 44, and communication paths 41 communicatively connecting these components.

[0079] The controller 50 comprises a processor 52 and a non-transitory electronic memory 54 to which various components are communicatively connected. In some embodiments, the processor 52 and the non-transitory electronic memory 54 and / or other components are included in a single device. In other embodiments, the processor 52 and the non-transitory electronic memory 54 and / or other components may be distributed among multiple communicatively connected devices. The controller 50 includes a non-transitory electronic memory 54 that stores a set of machine-readable instructions. The processor 52 executes the machine-readable instructions stored in the non-transitory electronic memory 54. The non-transitory electronic memory 54 may comprise RAM, ROM, flash memory, a hard drive, or any device capable of storing machine-readable instructions such that the machine-readable instructions may be accessed by the processor 52. Thus, the operating system 400 described herein may be implemented as a hardware element pre-programmed in any conventional computer programming language or as a combination of hardware and software components. The non-transitory electronic memory 54 may be implemented as a memory module or multiple memory modules.

[0080] In some embodiments, the non-transitory electronic memory 54 includes instructions for performing functions of the actuation system 400. The instructions can include instructions for operating the layered actuation structure 500, such as instructions for individually or collectively actuating one or more artificial muscles 100, and instructions for individually or collectively actuating the artificial muscle layers 210, 310.

[0081] The processor 52 may be any device capable of executing machine-readable instructions. For example, the processor 52 may be an integrated circuit, a microchip, a computer, or any other computing device. The non-transitory electronic memory 54 and the processor 52 are connected to a communication path 41 that provides signal interconnectivity between various components and / or modules of the operating system 400. Thus, the communication path 41 may communicatively connect any number of processors to each other, allowing the modules connected to the communication path 41 to operate in a distributed computing environment. Specifically, each of the modules may operate as a node that may transmit and / or receive data. The term "communicatively connected" as used herein means that the connected components can exchange data signals with each other, such as, for example, electrical signals through a conductive medium, electromagnetic signals through the air, optical signals through optical waveguides, etc.

[0082] As shown diagrammatically in Figure 13, a communication path 41 communicatively couples the processor 52 and non-transitory electronic memory 54 of the controller 50 to a number of other components of an actuation system 400. For example, the actuation system 400 shown in Figure 11 includes a processor 52 and non-transitory electronic memory 54 communicatively coupled to a control device 46 and a power source 48.

[0083] The manipulation device 46 allows a user to control the operation of the artificial muscles 100 of the layered actuation structure 500. In some embodiments, the manipulation device 46 may be a switch, a toggle, a button, or any combination of controls to provide user manipulation. The manipulation device 46 is connected to the communication path 41, which communicatively connects the manipulation device 46 to other modules of the actuation system 400. The manipulation device 46 may provide a user interface to accept user commands regarding a particular operational setting of the layered actuation structure 500.

[0084] The power source 48 (e.g., a battery) provides power to one or more artificial muscles 100 of the layered actuation structure 500. In some embodiments, the power source 48 is a rechargeable DC power source. It should be understood that the power source 48 can be a single power source or battery for powering one or more artificial muscles 100 of the layered actuation structure 500. A power adapter (not shown) can be provided and electrically connected, such as via a wiring harness, for providing power to one or more artificial muscles 100 of the layered actuation structure 500 via the power source 48. In effect, the power source 48 is a device that can receive power at one level (e.g., one voltage, power level, or current) and output power at a second level (e.g., a second voltage, power level, or current).

[0085] In some embodiments, the actuation system 400 also includes a display device 42. The display device 42 is connected to a communication path 41, which communicatively connects the display device 42 to other modules of the actuation system 400. In addition to providing optical information, the display device 42 may be a touch screen that detects the presence and location of tactile input on or adjacent to the surface of the display device 42. Thus, the display device 42 may include a control device 46 or may accept mechanical input directly on the optical output provided by the display device 42.

[0086] In some embodiments, the actuation system 400 includes network interface hardware 44 for communicatively connecting the actuation system 400 to a portable device 70 via a network 60. The portable device 70 may include, but is not limited to, a smart phone, a tablet, a personal media player, or any other electronic device that includes wireless communication capabilities. Of course, the portable device 70, if provided, may serve to provide user instructions to the controller 50 instead of the manipulation device 46. In this manner, a user may be able to utilize control of the manipulation device 46 to control or set a program for controlling the artificial muscles 100 of the layered actuation structure 500. Thus, the artificial muscles 100 of the layered actuation structure 500 may be remotely controlled by the portable device 70, which wirelessly communicates with the controller 50 via the network 60.

[0087] It should be understood that the embodiments described herein are directed to a layered actuation structure having one or more actuation platforms interleaved with one or more mounting platforms forming platform pairs. An artificial muscle is disposed in the actuation cavity of each platform pair and extends as needed to selectively elevate the actuation platform. The translational movement of each of the one or more actuation platforms generates an additive force that can be increased by adding additional platform pairs to the layered actuation structure. Each additional platform pair of the layered actuation structure increases the maximum achievable force without increasing the total displacement generated during actuation. Thus, the layered actuation structure is useful for small footprint applications, particularly laterally small footprint applications.

[0088] It should be noted that the terms "substantially" and "about" may be used herein to describe the inherent degree of uncertainty that can be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also used herein to describe the degree to which a quantitative representation may vary from a stated reference value without affecting the fundamental functionality of the subject matter under consideration.

[0089] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications can be made without departing from the scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter. The invention disclosed in this specification includes the following aspects. [Aspect 1] An artificial muscle drive unit, With the base, an artificial muscle having an expandable reservoir and a fluid, the fluid being movable within the expandable reservoir to switch the artificial muscle between a non-actuated state in which a dimension of the artificial muscle in a movement direction is at a minimum value and an actuated state in which the dimension of the artificial muscle is at a maximum value; A load support disposed on the base; Equipped with the load support has a dimension in the direction of movement that is greater than or equal to the minimum value; Artificial muscle drive unit. [Aspect 2] 2. The artificial muscle drive unit of claim 1, wherein the load support is offset from the expandable reservoir on the base. [Aspect 3] 2. The artificial muscle drive unit of claim 1, further comprising an actuation platform held in a spaced relationship relative to the base, wherein upon actuation of the artificial muscle from the unactuated state, the expansible reservoir moves the actuation platform a stroke distance in the direction of movement. Aspect 4 4. The artificial muscle drive unit of claim 3, wherein when the artificial muscle is in the unactuated state, the expansile reservoir and the actuation platform are offset in the direction of movement by an offset distance such that the artificial muscle first contacts the actuation platform in a partially actuated state where a distance between an outer surface of the expansile reservoir and the base is between the minimum and maximum values. Aspect 5 4. The artificial muscle drive unit of claim 3, wherein the offset distance is greater than the minimum value. Aspect 6 4. The artificial muscle drive unit of aspect 3, further comprising a plurality of load supports configured to maintain the actuation platform in a stationary orientation relative to the base when the artificial muscle is in the unactuated state. Aspect 7 7. The artificial muscle drive unit of claim 6, wherein in the rest position, the actuation platform extends perpendicular to the direction of movement. Aspect 8 2. The artificial muscle drive unit of claim 1, wherein the artificial muscle comprises a housing having an electrode region and an expansile fluid region, the expansile fluid region of the housing corresponding to the expansile reservoir. Aspect 9 the artificial muscle further comprises an electrode pair disposed in the electrode region of the housing, the electrode pair comprising a first electrode fixed to a first surface of the housing and a second electrode fixed to a second surface of the housing; The fluid comprises a dielectric fluid; the electrode pair being actuable between the unactuated state and the actuated state, and actuation from the unactuated state to the actuated state directs the dielectric fluid into the expansion fluid region and elongates the expansion fluid region in the direction of movement. 9. The artificial muscle drive unit of embodiment 8. Aspect 10 each of the first electrode and the second electrode includes two or more tab portions and two or more bridge portions; each of the two or more bridge portions interconnecting adjacent tab portions; At least one of the first electrode and the second electrode includes a central opening disposed between the two or more tab portions and surrounding the expandable fluid region. 10. The artificial muscle drive unit of embodiment 9. Aspect 11 2. The artificial muscle drive unit of claim 1, wherein the artificial muscle drive unit includes a plurality of artificial muscles stacked on top of each other in the direction of movement. Aspect 12 The artificial muscle drive unit of aspect 11, wherein when all of the plurality of artificial muscles are in the unactuated state, a dimension of the load support in the movement direction is equal to or greater than a total height of the plurality of artificial muscles in the movement direction. Aspect 13 1. An artificial muscle device, comprising: one or more actuation platforms interleaved with the one or more mounting platforms to define one or more actuation cavities between the one or more pairs of platforms; one or more artificial muscles disposed in each of the one or more actuation cavities; a load support disposed in at least one of the one or more working cavities; Equipped with each platform pair includes a respective mounting platform and a respective actuation platform, the one or more artificial muscles having an expansion reservoir and a fluid, the fluid movable within the expansion reservoir to actuate the one or more artificial muscles between an unactuated state in which a dimension of the one or more artificial muscles in a direction of movement is a minimum value and an actuated state in which the dimension is a maximum value in the direction of movement, and the load support has a dimension in the direction of movement that is equal to or greater than the minimum value; Artificial muscle device. Aspect 14 The one or more artificial muscles disposed in each of the one or more actuation cavities include a housing having an electrode region and an expandable fluid region; an electrode pair including a first electrode and a second electrode disposed in the electrode region of the housing; Equipped with the fluid comprises a dielectric fluid contained within the housing, and the electrode pair is actuable between the unactuated state and the actuated state such that actuation from the unactuated state to the actuated state directs the dielectric fluid into the expansion fluid region, thereby expanding the expansion fluid region and exerting pressure on the one or more actuating platforms to cause translational movement of the one or more actuating platforms. 14. The artificial muscle device of embodiment 13. Aspect 15 The one or more artificial muscles disposed in each of the one or more actuation cavities comprise an artificial muscle stack, the artificial muscle stack comprising: A plurality of artificial muscle layers, each of which comprises one or more artificial muscles; Each of the one or more artificial muscles comprises: Two or more tab portions; and It has two or more bridge sections, each of the two or more bridge portions interconnecting adjacent tab portions, and at least one of the first electrode and the second electrode includes a central opening disposed between the two or more tab portions and surrounding the expansion fluid region; The multiple artificial muscle layers are arranged such that the expandable fluid region of the one or more artificial muscles of each artificial muscle layer overlaps with at least one tab portion of the one or more artificial muscles of an adjacent artificial muscle layer. 15. The artificial muscle device of embodiment 14. Aspect 16 The artificial muscle device of aspect 15, wherein when the one or more artificial muscles of the multiple artificial layers are in the unactuated state, the dimension of the load support in the direction of movement is greater than or equal to a total height of the multiple artificial layers. Aspect 17 14. The artificial muscle device of claim 13, wherein when the one or more artificial muscles are in the unactuated state, the expandable reservoir and the actuation platform of the one or more artificial muscles in each actuation cavity are offset by an offset distance in the direction of movement such that the one or more artificial muscles first contact the actuation platform in a partially actuated state, where a distance between an outer surface of the expandable reservoir and the mounting platform is between the minimum and maximum values. Aspect 18 1. A method for operating an artificial muscle drive unit, comprising: Positioning the artificial muscle drive unit relative to a load source, whereby the load source applies a force to a load support of the artificial muscle drive unit, the load support being positioned relative to the artificial muscle of the artificial muscle drive unit such that the force is not applied directly to an expansile reservoir of the artificial muscle when the artificial muscle is in an inactive state; manipulating a fluid disposed within the expandable reservoir of the artificial muscle such that at least a portion of the expandable reservoir expands in a direction of movement prior to encountering the force applied to the load support and continues to expand in the direction of movement upon encountering the force applied by the load support, thereby providing an artificial muscle force to the load source; A method comprising: Aspect 19 Manipulating the fluid disposed within the expandable reservoir includes: providing a voltage using a power source electrically connected to an electrode pair of the artificial muscle, the artificial muscle comprising a housing having an electrode region and an expansion fluid region, the expansion fluid region corresponding to the expansion reservoir, the electrode pair disposed on the electrode region of the housing, the electrode pair comprising a first electrode secured to a first side of the housing and a second electrode secured to a second side of the housing, and the fluid comprising a dielectric fluid contained within the housing; applying the voltage to the electrode pair of the artificial muscle; thereby actuating the electrode pair from an unactuated state to an actuated state, and directing the dielectric fluid into the expansion fluid region of the housing, causing the expansion fluid region to expand, thereby providing force for the artificial muscle. The method according to embodiment 18. Aspect 20 the artificial muscle is one of a plurality of artificial muscles stacked in the movement direction, The artificial muscle drive unit includes a base and an actuation platform; the plurality of artificial muscles and the load support are disposed between the base and the actuation platform; the load support has a dimension in the direction of movement that is greater than a combined height of the plurality of artificial muscles in the unactuated state, such that the load support provides an offset between the plurality of artificial muscles and the actuation platform regardless of a force applied to the actuation platform by the load source. The method according to embodiment 18.

Claims

1. An artificial muscle drive unit, With the base, an artificial muscle having an expandable reservoir and a fluid, the fluid being movable within the expandable reservoir to switch the artificial muscle between a non-actuated state in which a dimension of the artificial muscle in a movement direction is at a minimum value and an actuated state in which the dimension of the artificial muscle is at a maximum value; A load support disposed on the base; Equipped with the load support has a dimension in the direction of movement that is greater than or equal to the minimum value; the artificial muscle comprises a housing having an electrode region and an expansion fluid region, the expansion fluid region of the housing corresponding to the expansion reservoir; the artificial muscle further comprises an electrode pair disposed in the electrode region of the housing, the electrode pair comprising a first electrode fixed to a first surface of the housing and a second electrode fixed to a second surface of the housing; The fluid comprises a dielectric fluid; the electrode pair being actuable between the unactuated state and the actuated state, and actuation from the unactuated state to the actuated state directs the dielectric fluid into the expansion fluid region and elongates the expansion fluid region in the direction of movement; each of the first electrode and the second electrode includes two or more tab portions and two or more bridge portions; each of the two or more bridge portions interconnecting adjacent tab portions; At least one of the first electrode and the second electrode includes a central opening disposed between the two or more tab portions and surrounding the expansion fluid region. Artificial muscle drive unit.

2. 2. The artificial muscle drive unit of claim 1, wherein the load support is offset from the expandable reservoir on the base.

3. 2. The artificial muscle drive unit of claim 1, further comprising an actuation platform held in spaced relation to the base, wherein upon actuation of the artificial muscle from the unactuated state, the expansible reservoir moves the actuation platform a stroke distance in the direction of movement.

4. 4. The artificial muscle drive unit of claim 3, wherein the expansile reservoir and the actuation platform are offset in the direction of movement by an offset distance when the artificial muscle is in the unactuated state such that the artificial muscle first contacts the actuation platform in a partially actuated state where a distance between an outer surface of the expansile reservoir and the base is between the minimum and maximum values.

5. The artificial muscle drive unit of claim 4 , wherein the offset distance is greater than the minimum value.

6. 4. The artificial muscle drive unit of claim 3, further comprising a plurality of load supports configured to maintain the actuation platform in a stationary orientation relative to the base when the artificial muscle is in the unactuated state.

7. The artificial muscle drive unit of claim 6 , wherein in the rest position, the actuation platform extends perpendicular to the direction of movement.

8. 2. The artificial muscle drive unit of claim 1, wherein the artificial muscle drive unit comprises a plurality of artificial muscles stacked on top of each other in the direction of movement.

9. 9. The artificial muscle drive unit according to claim 8, wherein when all of the plurality of artificial muscles are in the inoperative state, a dimension of the load support in the movement direction is equal to or greater than a total height of the plurality of artificial muscles in the movement direction.

10. 1. An artificial muscle device, comprising: one or more actuation platforms interleaved with the one or more mounting platforms to define one or more actuation cavities between the one or more pairs of platforms; one or more artificial muscles disposed in each of the one or more actuation cavities; a load support disposed in at least one of the one or more working cavities; Equipped with each platform pair includes a respective mounting platform and a respective actuation platform, the one or more artificial muscles having an expansion reservoir and a fluid, the fluid movable within the expansion reservoir to actuate the one or more artificial muscles between an unactuated state in which a dimension of the one or more artificial muscles in a direction of movement is a minimum value and an actuated state in which the dimension is a maximum value in the direction of movement, and the load support has a dimension in the direction of movement that is equal to or greater than the minimum value; The one or more artificial muscles disposed in each of the one or more actuation cavities include a housing having an electrode region and an expandable fluid region; an electrode pair including a first electrode and a second electrode disposed in the electrode region of the housing; Equipped with the fluid comprises a dielectric fluid contained within the housing, and the electrode pair is actuable between the unactuated state and the actuated state such that actuation from the unactuated state to the actuated state directs the dielectric fluid into the expansion fluid region, thereby expanding the expansion fluid region and exerting pressure on the one or more actuating platforms to cause translational movement of the one or more actuating platforms; The one or more artificial muscles disposed in each of the one or more actuation cavities comprise an artificial muscle stack, the artificial muscle stack comprising: A plurality of artificial muscle layers, each of which comprises one or more artificial muscles; Each of the one or more artificial muscles comprises: Two or more tab portions; and Two or more bridge portions are provided, each of the two or more bridge portions interconnecting adjacent tab portions, and at least one of the first electrode and the second electrode including a central opening disposed between the two or more tab portions and surrounding the expansion fluid region; The plurality of artificial muscle layers are arranged such that the expandable fluid region of the one or more artificial muscles of each artificial muscle layer overlaps with at least one tab portion of the one or more artificial muscles of an adjacent artificial muscle layer. Artificial muscle device.

11. 11. The artificial muscle device of claim 10, wherein when the one or more artificial muscles of the plurality of artificial muscle layers are in the unactuated state, the dimension in the direction of movement of the load support is equal to or greater than a combined height of the plurality of artificial muscle layers.

12. 11. The artificial muscle device of claim 10, wherein the expansile reservoir and the actuation platform of the one or more artificial muscles in each actuation cavity are offset in the direction of movement by an offset distance when the one or more artificial muscles are in the unactuated state such that the one or more artificial muscles first contact the actuation platform in a partially actuated state, where a distance between an outer surface of the expansile reservoir and the mounting platform is between the minimum and maximum values.

13. 1. A method for operating an artificial muscle drive unit, comprising: Positioning the artificial muscle drive unit relative to a load source, whereby the load source applies a force to a load support of the artificial muscle drive unit, the load support being positioned relative to the artificial muscle of the artificial muscle drive unit such that the force is not applied directly to an expansile reservoir of the artificial muscle when the artificial muscle is in an inactive state; manipulating a fluid disposed within the expandable reservoir of the artificial muscle such that at least a portion of the expandable reservoir expands in a direction of movement prior to encountering the force applied to the load support and continues to expand in the direction of movement upon encountering the force applied by the load support, thereby providing an artificial muscle force to the load source; Including, Manipulating the fluid disposed within the expandable reservoir includes: providing a voltage using a power source electrically connected to an electrode pair of the artificial muscle, The artificial muscle includes a housing having an electrode region and an expandable fluid region, the expansion fluid region corresponds to the expansion reservoir; the electrode pair is disposed in the electrode region of the housing; the electrode pair includes a first electrode fixed to a first surface of the housing and a second electrode fixed to a second surface of the housing; The fluid comprises a dielectric fluid contained within the housing; each of the first electrode and the second electrode includes two or more tab portions and two or more bridge portions; each of the two or more bridge portions interconnecting adjacent tab portions; At least one of the first electrode and the second electrode includes a central opening disposed between the two or more tab portions and surrounding the expandable fluid region; and applying the voltage to the electrode pair of the artificial muscle; thereby actuating the electrode pair from an unactuated state to an actuated state, and directing the dielectric fluid into the expansion fluid region of the housing, causing the expansion fluid region to expand, thereby providing force for the artificial muscle. method.

14. the artificial muscle is one of a plurality of artificial muscles stacked in the movement direction, The artificial muscle drive unit includes a base and an actuation platform; the plurality of artificial muscles and the load support are disposed between the base and the actuation platform; the load support has a dimension in the direction of movement that is greater than a combined height of the plurality of artificial muscles in the unactuated state, such that the load support provides an offset between the plurality of artificial muscles and the actuation platform regardless of a force applied to the actuation platform by the load source. The method of claim 13.

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