Hydraulically amplified soft electrostatic actuators for automotive surfaces and human machine interfaces

A seating system includes a seat, with structures for supporting a user thereon, and actuators. Each actuator includes a deformable shell with an enclosed internal cavity containing a fluid dielectric contained, a pair of electrodes disposed on opposing sides of the deformable shell. The actuators are integrated into the structures and configured for providing at least one function, such as haptic feedback, seat adjustment, alert notification, vibratory signal, user input receiving, and massage function. A portion of the plurality of actuators may be enclosed within an encapsulating shell to form an encapsulated sheet of actuators. Each actuator may be a part of a button-on-demand system, wherein the actuator is normally in a collapsed position such that a user-facing surface of the encapsulating shell is substantially flat and, when activated by a user, the actuator is configured to expand such that the encapsulating shell is raised to form a button.

FIELD OF THE INVENTION

The present invention relates to actuator systems. In particular, but not by way of limitation, the present invention relates to soft actuator systems suitable for use with surfaces and interfaces in automotive applications and other human machine interfaces.

DESCRIPTION OF RELATED ART

Human-machine interfaces are important parts of everyday life. While most interfaces, such as LCD displays, provide visual feedback, there are many opportunities for interfaces that provide physical or tactile feedback and stimulation. Tactile feedback can be used to communicate information to users or provide alerts. New tactile interfaces can be beneficial for environments where users have to process a large amount of sensory input, such as driving an automobile through heavy traffic and/or poor conditions. Besides communicating information, tactile stimulation can be useful for improving user experience and comfort. Examples include chairs with massage function or vibration that is synchronized with a sound system.

Modern automotive seats often include motorized or pneumatic actuators for adjusting driver or passenger position. Additionally, some seats even include massage systems for user comfort. Actuators used for these systems are typically powered by electric motors or pneumatic bladders. Systems based on electric motors require several moving mechanical parts which can be complex. Similarly, pneumatic systems require pumps and valves which add to overall system size and complexity.

Most haptic actuators today are either eccentric rotating motors (ERMs), linear resonant actuators (LRAs), or voice coils actuators (VCAs). While these actuators are great for providing vibrations in the 100-300 Hz range, most haptic devices today transmit information by buzzing at different frequencies, durations, and intensity.

However, most of our physical interactions-such as clicking a button, grasping an object, or embracing a loved one-occur at much lower frequencies and are not adequately represented by the buzzing of traditional haptic actuators. In fact, important nerve endings known as Meissner corpuscles are the most sensitive to motion within the range of 10-50 Hz. Additionally, slowly adapting (SA) mechanoreceptors are responsive to frequencies as low as 0.4 Hz and are important for perceiving shapes and direction of motion along the skin. Sensations on these low frequencies can be imitated with various tricks using traditional haptic actuators, but the effect is a poor representation of reality.

Furthermore, ERMs, LRAs, and VCAs are all actuated by electromagnetic forces. As a result, they are made from a variety of rigid materials and require several moveable parts. Besides added complexity, these factors make it difficult to integrate electromagnetic actuators into devices such as wearables that need to be comfortable and unobtrusive for a user. Additionally, due to the mechanical impedance mismatch of stiff rigid materials and soft human tissue, the transfer of energy from an electromagnetic actuator to a user is inefficient.

Improved actuators that may be readily integrated into a variety of human-machine interfaces without adding undue complexity while providing heretofore unavailable features would be desirable.

SUMMARY OF THE INVENTION

In an embodiment, a seating system includes a seat, in turn including structures for supporting a user thereon, and a plurality of actuators. Each actuator includes a deformable shell defining an enclosed internal cavity, a fluid dielectric contained within the enclosed internal cavity, a first electrode disposed on a first side of the deformable shell, and a second electrode disposed on a second, opposing side of the deformable shell. The plurality of actuators are integrated into the structures of the seat, and the plurality of actuators are configured for providing at least one function, the function including haptic feedback, seat adjustment, alert notification, vibratory signal, user input receiving, and massage function.

In certain embodiments, a portion of the plurality of actuators are enclosed within an encapsulating shell to form an encapsulated sheet of actuators. For example, the encapsulating shell may be formed of a material providing at least one of electrical insulation, thermal insulation, electrical isolation between neighboring actuators contained within the encapsulating shell, and cushioning.

In other embodiments, at least one of the actuators enclosed within the encapsulating shell is configured to operate as a button on demand. The at least one of the actuators enclosed within the encapsulating shell is normally in a collapsed position such that a user-facing surface of the encapsulated sheet of actuators is substantially flat. When activated by a user, the at least one of the actuators within the encapsulating shell may be configured to expand such that a portion of the user-facing surface of the encapsulated sheet of actuators is raised to form a button.

In certain embodiments, the at least one of the actuators within the encapsulating shell is configured to be activatable when touched by the user. In other embodiments, the encapsulating sheet of actuators further contains at least one proximity sensor, and the at least one of the actuators within the encapsulating shell is in electrical communication with the at least one proximity sensor such that the at least one of the actuators within the encapsulating shell is activatable when the at least one proximity sensor senses the user within a predetermined distance from the encapsulated sheet of actuators.

In a further embodiment, the seating system includes a control system electrically coupled with the plurality of actuators for controlling the at least one function.

In another embodiment, a seating system includes a seat including structures, for supporting a user thereon, and a plurality of actuators. Each actuator includes a deformable shell defining an enclosed internal cavity, a fluid dielectric contained within the enclosed internal cavity, a first electrode disposed on a first side of the deformable shell, and a second electrode disposed on a second, opposing side of the deformable shell. The seating system further includes an encapsulating shell enclosing the plurality of actuators therein to form an encapsulated sheet of actuators. The plurality of actuators may be configured for providing at least one function, the function including haptic feedback, seat adjustment, alert notification, vibratory signal, user input receiving, and massage function.

In certain embodiments, the encapsulated sheet of actuators is integrated into the structures of the seat. In other embodiments, the encapsulated sheet of actuators is disposed adjacent to the seat. In an alternative embodiment, the encapsulated sheet of actuators may be affixed on a surface of the seat using at least one of adhesives, tape, belts, hooks, snaps, and hook-and-loop attachments. The seating system may further include a control system electrically coupled with the plurality of actuators for controlling the at least one function.

In another embodiment, a button-on-demand system, includes an actuator. The actuator includes a deformable shell defining an enclosed internal cavity, a fluid dielectric contained within the enclosed internal cavity, a first electrode disposed on a first side of the deformable shell, and a second electrode disposed on a second, opposing side of the deformable shell. The system also includes an encapsulating shell at least partially containing the actuator. In an example, the actuator is normally in a collapsed position such that a user-facing surface of the encapsulating shell is substantially flat and, when activated by a user, the actuator is configured to expand such that a portion of the user-facing surface of the encapsulating shell is raised to form a button.

In an example, the actuator is configured to be activatable when touched by the user. In certain embodiments, the system further includes a proximity sensor. The actuator may be in electrical communication with the proximity sensor such that the actuator is activatable when the proximity sensor senses the user within a predetermined distance from the button-on-demand system.

For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the embodiments detailed herein. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of the described embodiments. The same reference numerals in different figures denote the same elements.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. In the following detailed description, references are made to the accompanying drawings that form a part hereof, and in which are shown by way of illustrations or specific examples. These aspects may be combined, other aspects may be utilized, and structural changes may be made without departing from the present disclosure. Example aspects may be practiced as methods, systems, or apparatuses. The following detailed description is therefore not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims and their equivalents.

DETAILED DESCRIPTION OF THE INVENTION

It will be understood that when an element or layer is referred to as being “on,” “connected to,” “coupled to,” or “adjacent to” another element or layer, it can be directly on, connected, coupled, or adjacent to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “immediately adjacent to” another element or layer, there are no intervening elements or layers present. Likewise, when light is received or provided “from” one element, it can be received or provided directly from that element or from an intervening element. On the other hand, when light is received or provided “directly from” one element, there are no intervening elements present.

The typical passenger automobile includes several human-machine-interfaces that could benefit from tactile feedback and stimulation. Systems for providing tactile stimulation and feedback using hydraulically amplified soft electrostatic actuators are presented. These include actuators and associated components for integration into various user interfaces. In particular we focus on interfaces found within automobiles and other vehicles although many concepts could be used in other applications involving human-machine-interfaces

Here we describe new actuators and systems that utilize hydraulically amplified soft electrostatic (HASEL) actuators for tactile feedback and stimulation. HASEL actuators provide benefits such as direct electrical control which provides very fast response times and simplifies overall system size and complexity. The inherent compliance of HASEL actuators makes them ideal for providing tactile sensations. HASEL actuators can be made into many different sizes and shapes for different user interfaces. Additionally, the self-sensing capability of HASEL actuators can allow for interfaces with dual functionality.

While HASEL actuators operate on relatively high voltages (e.g., 3-6 kV), the actuators may be safely insulated, for example, by encapsulating the actuators within polymers, elastomers, or other materials known in flexible electronics. Further, the operating current is quite low (<<1 mA) such that, if a short were to occur due to failure of the electrical insulation, the total electrical power is well below the threshold for dangerous electrical discharge that may harm a user. In fact, the actuators used in the described embodiments below may be operated with portable power supplies with power ratings as low as 5 W, and may be battery powered. Also, due to the low current requirements, the actuators used in the described embodiments herein consume only a small amount of power. For example, power consumption at 40 Hz has been measured as ranging from 2.0 W at peak (0.4 W root mean square (RMS)) for a single layer actuator to 10.2 W peak (3.8 W RMS) for a 14-actuator stack.

Additionally, with such low power consumption, the actuators used in the embodiments described herein do not generate heat during operation. This characteristic is especially beneficial for applications that are sensitive to temperature or may require a multitude of actuators. Further, as the actuators used in embodiments described herein to not require metal components, the systems and embodiments described below are capable of operating in environments that are sensitive to magnetic fields. Further, the actuators used in embodiments described herein do not require moving, mechanical parts and, consequently, are nearly silent during operation while providing movement and sensations over a wide frequency range (e.g., 0-200 Hz).

It is noted that, in many seating applications including for automotive seating, office chairs, and gaming seats, the seat structure often include a frame covered by foam components and enclosed in a cover. The actuators used in embodiments described herein may be integrated into the foam, positioned between the foam and the cover within the seat structure, integrated into the cover (e.g., sandwiched between material layers forming the cover) and/or placed on the cover as an optional add-on or as an after-market addition by the user.

The systems described here are focused on user interfaces within an automobile, and are applicable for a variety of applications outside of automotive contexts. Actuators incorporated to seats can serve several purposes. Actuators can provide massage sensations or can be configured to provide haptic feedback for hazard detection or notifications from communication devices. Actuators within a seat can also be synchronized with music or entertainment, or activated on demand, for example, for adjusting the seat according to user preferences. Such capabilities are enabled by the soft actuator configurations described herein, which provide wide bandwidth, controllable actuation using soft and flexible materials, offering sensations and actuation beyond simple vibration.

User experience and aesthetics can be improved by incorporating actuators to surfaces that are touched by users. Actuators can be integrated into center consoles, doors, dashboards, and steering wheels to provide tactile information. Compact HASEL actuators can transform a flat surface to a surface with one or more raised segments which function as so-called buttons-on-demand.

While the systems described here are focused on automobiles, they can be readily applied to other vehicles such as airplanes, trains, aircraft, underwater vehicles, etc. Further, these systems can be useful in other situations. Seating for entertainment or work can benefit from tactile actuators. Likewise, tactile sensations can enhance user immersion for virtual reality applications. Many medical situations would benefit from tactile sensations as well. For example, patient beds and seats could utilize HASEL actuators to provide massage and vibration that helps stimulate blood flow and prevent injuries such as bed sores.

FIG.1shows an exemplary structure of a HASEL actuator100. A flexible shell or pouch102defines an enclosed internal cavity that is filled with a liquid dielectric104. Flexible shell102may be formed from at least one dielectric material. In an example, flexible shell102is formed of a material that is inextensible and/or elastically deformable. A first electrode106is disposed over a first side of the enclosed internal cavity and a second electrode108is disposed over a second side of the enclosed internal cavity opposite the first side. As shown inFIG.1, first and second electrodes106,108are placed on opposing sides of flexible shell102, extending toward the tapered end of the shell, in an example.

In an initial state where applied voltage V0is null or small, flexible shell102may exhibit an initial length112and thickness116.

FIG.1illustrates a cross-sectional view of an exemplary, basic HASEL structure. Three-dimensional circular pouch shapes can be formed by revolving this cross-section around an axis at either a left boundary118or a right boundary120, as an example. Likewise, this cross section can be extruded in a direction that is normal to the page to form a rectangular or oval pouch shape. Other pouch shapes may be contemplated based on this basic configuration where part of a flexible shell is covered by a pair of electrodes positioned on opposing sides of the flexible shell.

Multiple flexible shells102may be positioned adjacent to each other or connected together at either left boundary118or right boundary120to form a multi-pouch actuator in the horizontal direction (i.e., x or y direction as shown inFIG.1). Likewise, flexible shells can be stacked in the z direction to create a multi-pouch actuator. In certain examples, a solid plate may be positioned adjacent to the multi-pouch actuator or in between the pouches, such as shown inFIGS.8A and8B, as will be described at an appropriate juncture below.

Pouch length112may be varied depending on the application and desired performance. For instance, a pouch length ranging from 0.5 mm to 100 mm may be contemplated. As an example, initial thickness116may range from 0.1 mm to 10 mm. The length of each one of electrodes108and106is typically a fraction of pouch length112and may range from 10% to 90% of pouch length112.

Flexible shell102may be made from one or more dielectric and non-dielectric layers with various thicknesses. A suitable polymer film for forming flexible shell102may include biaxially-oriented films such as polyester, polyethylene terephthalate, and polypropylene. Other films include polyvinylidene fluoride (PVDF), co-polymers, terpolymers (e.g., poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)), polytetrafluoroethylene (PTFE), and thermoplastic polyurethane (TPU). In certain embodiments, films with a dielectric permittivity greater than 2 and dielectric strength greater than 30 kV/mm may be selected. Films may be doped with nanoparticles such as titanium dioxide, barium titanate, and other semiconductor materials to increase permittivity and therefore increase actuator performance. Thickness of the film forming flexible shell102may be less than 50 μm, for example. Flexible shell102may be formed of multiple layers of dielectric materials to increase dielectric performance. Additionally, layers for providing improved mechanical performance may be laminated with the dielectric layer of the flexible shell. Flexible shell102may be formed from a variety of techniques including heat-sealing, ultra-sonic sealing, adhesives, plasma treatment, laminating, or laser sealing.

Liquid dielectric104may include one or more fluids such as natural esters (e.g., FR3® natural ester dielectric fluid from Cargill, Inc.), silicone oils, and mineral oils to name a few. The fluid may be doped with nanoparticles such as titanium dioxide, barium titanate, and other semiconductor materials to increase permittivity and therefore increase actuator performance, in certain embodiments. In some embodiments, liquid dielectric104may be a dielectric gas or combination of gas and liquid. Volume of liquid within a pouch generally depends on pouch length and desired thickness and may range from 0.01 mL to 10 mL in each pouch.

Electrodes106and108may be selected from a number of conductive materials that may be applied by various processes. Electrodes may be flexible and stretchable, or in some cases fully or partially rigid. Possible materials include metallized films that are vacuum deposited onto flexible shell102, screen-printed conductive inks, conductive elastomers, metals, and conductive polymers.

FIG.2illustrates actuator100ofFIG.1with a voltage V1applied. Applied voltage V1causes charges220,222of opposing polarity to flow onto electrodes106and108. Charges220,222act to induce an electric field224(represented by white-headed arrows) through flexible shell102and liquid dielectric104. Electric field224is generally concentrated through length210where the electrodes have zipped together and through liquid dielectric104at the edge of a tapered boundary216where electrodes106and108are closest together. This concentration of electric field224causes the tapered region to experience a high electrostatic stress and, in response, electrodes106,108zip or move closer together. As the electrodes zip together by a length210, liquid dielectric104is displaced to the portion of flexible shell that has not zipped together. This displacement causes flexible shell102to deform such that length112′ decreases and thickness116′ increases. Concurrently, a hydrostatic pressure226(indicated by arrows) of liquid dielectric104increases. The increased internal hydrostatic pressure226combined with the deformation of flexible shell102imparts an external force in the vertical and horizontal directions (indicated respectively by thick arrows228and230, respectively). These forces and shape change may be used for performing mechanical work on external objects or surfaces.

FIG.3illustrates the actuator with voltage V2applied, which is greater in magnitude than V1and is sufficient for complete zipping together of the electrodes. In this case, electrodes106,108have fully zipped together. Liquid dielectric104contained in flexible shell102has been displaced to the portion of the pouch not covered by electrodes, which causes the pouch to further deform and increases the value of hydrostatic pressure226″. Consequently, length112″ is reduced to a minimum value and thickness116″ increases to a maximum value.

FIG.4shows the top view of a circular HASEL actuator400, in accordance with an embodiment. Actuator400includes a circular pouch402, which is filled with a dielectric liquid or gas (not visible inFIG.4) and divided into four sections by a vertical seal404and a horizontal seal406, in the illustrated embodiment. Electrodes408are positioned on opposing sides of pouch402in or near the middle of the pouch (only the top electrode is visible inFIG.4). In an example, the electrodes are generally circular and positioned concentrically with circular pouch402. It should be appreciated that portion of the circular pouch covered with an electrode may be inverted, such that the central part of the pouch is not covered with electrodes (e.g., a circular pouch with “donut”-shaped electrodes disposed concentrically on opposing sides of the pouch). Further, while the electrodes are shown as being generally circular, other shapes, such as semicircular, wedge-shaped, oval, and others, are also contemplated and considered a part of the present disclosure. Connections410and412for each electrode (e.g., connection410from the top electrode and connection412from the bottom electrode, not shown) may extend past the perimeter of the pouch, for use in applying a voltage across the electrodes to operate the actuator. Optionally a “skirt” of extra film material414may surround circular pouch402.

FIG.5Aillustrates a cross-sectional view of actuator400, viewed along a dashed line A-A indicated inFIG.4. In an example,FIG.5Ashows actuator400in a rest state where little or no voltage V0is applied thereto. As shown inFIG.5A, actuator400exhibits a thickness502and a radius506.

FIG.5Bshows actuator400′ once a voltage V2(where V2>>V0) has been applied and the electrodes have fully zipped together. This zipping motion has caused the actuator radius to reduce to506′, while the actuator thickness has increased to502′.

FIGS.6A and6Bshow perspective views of a HASEL actuator system600with a rectangular pouch shape. As an example, the actuator cross section shown inFIG.1may be extruded in a direction perpendicular to the page to form a pouch of a given width, as shown inFIGS.6A and6B. Although it is not shown, the ends of the pouches in the x-z plane would be sealed off to create an entirely closed pouch. Additionally, HASEL actuator system600includes two actuators602and604, which are connected together in series. The configuration of HASEL actuator system600may be advantageous in certain embodiments, as actuation stroke for a given load will increase proportionally with the number of actuators connected in series.

The electrode pairs of each actuator may be electrically isolated from each other such that a distinct voltage may be applied to each electrode to individually address each actuator. In an example, the voltage applied to the electrode pair in each actuator may be provided from multiple voltage sources to independently address the electrode pair of each actuator. Alternatively, the voltage provided by the electrode pairs for all of the actuators may be provided from a single voltage source, or the electrodes on two or more of the actuators may be connected together so that the actuators with the connected electrodes may be activated by simultaneously and/or by a single voltage source.

FIG.6Aillustrates an example where a voltage V0is applied across actuator602, and a different voltage V1is applied across actuator604. In the case shown inFIG.6A, each of the applied voltages V0and V1is too small to cause the respective electrodes to zip together.

InFIG.6B, actuator system600′ is shown with a voltage V2is applied across the electrodes of actuator602′, and a voltage V3is applied across the electrodes of actuator604′, where each of voltage V2and V3is sufficiently high to cause the electrodes of actuator602′ and actuator604′ to fully zip together. As a result, the thickness of actuators602′ and604′ have increased in the z-direction, while the overall length of actuator system600′ has decreased in along the x-axis, and the actuator exerts a contractile force606along the x-axis and an expanding force608in a z-direction. WhileFIGS.6A and6Bshows the lower electrode in each pair of electrodes connected to a ground source, it should be appreciated that only a voltage differential is needed to create an electric field between the electrodes thus, conversely, the top electrode of one or more of the electrode pairs may be grounded instead.

FIG.7shows an encapsulated HASEL actuator700. Encapsulation can serve multiple purposes including but not limited to electrical insulation, abrasion resistance, thermal insulation, and general protection of the actuator mechanism during use. In this case illustrated inFIG.7, actuator700includes a flexible shell702formed of two layers containing liquid dielectric104therein. In an example, an inner layer704and an outer layer706may have different material properties that combine to improve actuator performance. For instance, inner layer704may be formed of a high permittivity material while outer layer706may be formed of a material with superior mechanical properties. Inner and outer layers704and706may be fused or joined together through various physical or chemical processes. While electrodes106and108are shown as being located outside of outer layer706, it should be appreciated that electrodes106,108may instead be located between the inner and outer shell layers.

Further, an encapsulating layer710may be formed around the combination of the flexible shell and the electrodes. Encapsulating layer710may form an outer pouch that may be filled with another encapsulating material712such as a liquid dielectric or simply an airgap. Alternatively, encapsulating layer710may be directly bonded to flexible shell702and/or electrodes106,108, without any additional space formed therebetween. Additionally, although only one actuator arrangement is shown contained in encapsulating layer710, it is appreciated that multiple actuators may be contained within the encapsulating layer, as will be described in further detail at an appropriate point below.

It is noted that a single layer of actuators is quite thin (e.g., 0.3 mm in thickness), which is ideal for integrating into a variety of flexible structures. In certain embodiments, actuator stroke may be increased by stacking multiple actuators together.

FIGS.8A and8Billustrate another variation on encapsulation of a HASEL actuator system, in accordance with an embodiment. Encapsulation may provide a variety of advantages, such as providing electrical, thermal, and/or mechanical insulation of the actuators and their associated electronic circuitry from any surface (e.g., the attachment surface or the user coming into contact with the actuator system. In certain cases, the actuator system may include encapsulation in flexible materials, such as an elastomer, which enables the actuator system to be safe to touch, conform to different shapes, and/or withstand repeated bending and twisting.

As shown inFIG.8A, an actuator system800includes several actuators801placed in a stacked configuration. Each actuator801may be, for example, actuator400ofFIGS.4-5B. The stacking of actuators801may result in larger total change in thickness when the stacked actuators are activated. The top and bottom of the actuator stack is covered with a top plate806and a bottom plate808. In an embodiment, each of top and bottom plates806and808are of a sufficient stiffness such that the plates distribute the expanding force from the actuators over a larger area of the plates. In some embodiments, the top and bottom plates may instead be positioned between actuators801within the stack. In certain embodiments, spacer plates (not shown) may be inserted between actuators801in addition to top and bottom plates806and808(see, for example, Mitchell, et al., “An Easy-to-Implement Toolkit to Create Versatile and High-Performance HASEL Actuators for Untethered Soft Robots,” Advanced Science, 2019, 6, 1900178).

Referring concurrently toFIGS.8A and8B, stack of actuators801is contained within an encapsulating layer820. In an example, encapsulating layer820may be formed of a flexible, elastic, and/or stretchable material. Encapsulating layer820may serve multiple purposes including but not limited to electrical insulation, abrasion resistance, and/or providing an elastic restoring force. Encapsulating layer820may be filled with a filler material822, such as air or with dielectric fluids. As shown inFIG.8B, once fully activated, the encapsulated stack of activated actuators801′ provides expanding forces830in the z-direction. As shown, top and bottom plates806and808may also serve to distribute the expanding force provided by each one of the activated actuators along the surface area of the plates to act on objects placed in contact with actuator system800.

The HASEL actuators incorporated into various actuator systems described herein are also capable of self-sensing their deformation based on the capacitance of the electrodes. Referring back toFIGS.1-3, actuator capacitance is directly related to the area of the electrodes that have zipped together. For instance, when electrodes are fully zipped, capacitance of the actuator will be high. Applying a load to a fully zipped actuator (e.g., pushing down on the actuator pouch) will cause the capacitance to decrease as the electrodes unzip. Measurements for capacitive sensing may be integrated with the actuator driving signal, thus allowing for simultaneous sensing and actuation. This combination of actuation and sensing for two-way haptic communication may be beneficial for haptic applications that may have limited space for actuators and sensors. For example, a button could detect when a user presses it and simultaneously provide some haptic feedback (e.g., vibration) to the user to acknowledge the user input.

FIG.9shows an actuator system900including an array of HASEL actuator stacks910encapsulated within an encapsulating shell920to form an encapsulated sheet of actuators, in accordance with an embodiment. Actuator system900ofFIG.9is shown to contain an array of six actuator stacks910, each actuator stack910being configured to be independently addressable to provide localized expansion, such as in the shape of a button930.

In an example, encapsulating shell920includes a top layer940and a bottom layer942connected via a side layer944to contain the array of actuator stacks910. In some cases, side layer944may be integrally formed as a part of top layer940or bottom layer942. In certain embodiments, additional side layers or internal seams (not shown) may be provided around each actuator stack910such that each actuator stack910is isolated from each other actuator stack910contained within encapsulating shell920.

Encapsulating shell920may provide, for example, electrical insulation, thermal insulation, and/or abrasion resistance around each actuator stack910. The materials used for top, bottom, and side layers940,942, and944may be elastic and/or flexible. Possible materials suitable for use as a part of encapsulating shell920are, but not limited to, elastomers, polymers, and fabrics. In certain embodiments, top layer940, bottom layer942, and/or side layer944may be formed of different materials. For instance, in some applications, bottom layer942may be formed of a stiff material to provide a stable backing for actuator system900, while top layer940is formed of an elastomer such that actuator stacks910, when activated, provides an expansive force toward top layer940to form button930. In an example, top layer940, bottom layer942, and side layer944may be configured to contain a liquid (e.g., a liquid dielectric) or a gas (e.g., air) to provide cushioning and/or additional electrical insulation for a user or another object to safely contact actuator system900.

Actuator stacks910contained within encapsulating shell920may be individually addressable or electrically connected with each other. Independent control of actuator stacks allows for a variety of actuation patterns that can provide massage or haptic sensations. Further, individual actuators within actuator stacks910may be individually addressed to provide additional granularity in the behavior of each actuator stack. For instance, patterned electrodes (not shown) may be integrated into encapsulating shell920or provided on an internal surface of top, bottom, and/or side layers940,942, and944to enable each actuator stack910to be electrically coupled with a voltage source located outside of encapsulating shell920. As an example, the patterned electrodes provided within or on a surface of encapsulating shell920may be electrically coupled to a power supply via connectors950and952. For instance, one of connectors950and952may be connected with a ground. In some cases, a separate set of connectors may be provided for each actuator stack910, or additional switch features may be incorporated into encapsulating shell920and/or actuator stacks910to enable individual addressing of each actuator stack. In certain embodiments, top layer940or bottom layer942may provide a common ground connection for some or all of the actuator stacks contained within encapsulating shell920.

In certain embodiments, encapsulating shell may contain one or more proximity sensors960. Proximity sensor960may be configured, for example, to sense when a part of a user (e.g., a finger or a hand) is within a predetermined distance from the encapsulating shell then, when sensor960is electrically coupled with one or more of the actuator stacks within the encapsulating shell, the one or more of the actuator stacks become activated. In certain cases, the activated actuator stack may force the associated button to protrude from a user-facing surface of encapsulating shell920. Alternatively, activation of the actuator stack may sensitize that actuator stack to be responsive to subsequent user input (e.g., to be touched or pushed by the user to receive user input) without changing the shape of the associated button. In other cases, the actuator stack may be activated by sensing the user touching the associated button. In certain cases, a portion of the actuators in the actuator stack may be configured to function as a sensor, while a different portion of the actuators in the actuator stack may be configured for controlling the protrusion of the button. Further, when an array of actuator stacks are used, as shown inFIG.9, one of the actuator stacks may function as a button-on-demand, in collaboration with a proximity sensor or touch sensing, while other actuator stacks perform other functions, such as providing vibration or sensory feedback to the user. That is, an array of actuator stacks may include actuator stacks performing different functions and, in certain cases, different actuators within a single stack of actuators may perform different functions.

FIG.10shows a schematic for a high voltage power supply (HVPS)1000for providing single- or multi-channel control for controlling one or more actuators, in accordance with certain embodiments. In an example, a high voltage (HV) rail1002is set to the maximum desired actuation voltage. The HV source (not shown) providing the high voltage to HV rail1002may be, for example, a HV amplifier or HV power supply. As shown inFIG.10, each HV diode1004is configured to prevent the flow of charges back to HV rail1002or between channels that are operating at different electrical potentials. Typically, HV diodes1004may be required with directional components used with HV switches, such as optocouplers. In certain embodiments, HV diodes may prevent transients from affecting the rest of the circuitry, thus protecting the other circuitry and making the overall actuator system safer and more reliable. In an example, HV diodes may prevent any HV transients caused by the actuators (i.e., overvoltage) from affecting the HV source or other actuators connected to different channels.

HV power supply1000may be configured to drive the actuators with a single polarity (i.e., one electrode is driven to a high voltage to charge the actuator while the other electrode remains connected to a low potential/ground), as indicated by a dashed box1018. Alternatively, HV power supply1000may be configured with reversing polarity in an H-bridge configuration (i.e., either electrode can be driven to high voltage or connected to ground), as indicated by a dashed box1020.

In either configuration, a first HV switch to charge1006is controlled with a first low voltage control signal1008(indicated by an arrow) to distribute charges from the HV rail to an actuator1016at the output of a channel, such as connected with connector950ofFIG.9. The conductance of HV switch1006may be controlled by first low voltage control signal1008to vary the amount of charge stored by the actuator and therefore its activation state. First HV switch1006may include for example, but not limited to, a reed relay, an optocoupler, a MOSFET, or an IGBT.

A second HV switch to discharge1010may be controlled with a second low voltage control signal1012(represented by an arrow) to distribute charges from actuator1016, for example from connector952ofFIG.9, to ground1003. The conductance of second HV switch1010may be controlled by second low voltage control signal1012to vary the amount of charge stored by actuator1016and again its activation state. A voltage monitor1014may be used to measure the voltage at the output of connections950and952. As an example, a voltage divider may be used to generate a low voltage replica of the HV signal measurable using traditional microcontrollers operating at, for instance, 3.3V.

This multi-channel power supply configuration may be extended to an arbitrary number of channels, N, to drive N actuators in single polarity configuration or N/2 actuators in reversing polarity configuration (as indicated by ellipsis1022). One actuator1016(or a stack of actuators addressed as a stack) may be placed at the output of each channel (e.g., electrically coupled with connectors950and952) and may exhibit a variable capacitance. Analog HV switches, such as optocouplers or MOSFETs, may be used to distribute charges from a centralized HV amplifier (i.e., HV rail1002set to a desired voltage) to an arbitrary number of output channels. In this way, HV power supply1000is advantageous in that it does not require a highly dynamic HV amplifier that can quickly change its full-scale voltage output. Further, as the HV source is often the largest and most expensive component of the actuator system, the present configuration provides a significant size and cost advantage in that only a single HV source may be required to provide an arbitrary number of independently controlled outputs.

The architecture of HV power supply1000is effectively a charge-controlled driving scheme, where charges are added to the output channel using the charging switch and/or removed from the output using the discharging switch. Since the switches are independently activated, charges can be added or removed from the output in order for the output to reach and/or maintain a desired state. That is, the outputs can be at or below the voltage of the HV rail at any desired voltage level, and the desired voltage may be achieved at a nearly arbitrary rate. Therefore, this architecture enables substantially arbitrary control of an arbitrary number of outputs, both in terms of state and rate at which the outputs reach that desired state.

Importantly, the use of a discharging switch allows active control of the state of actuation during discharge as well as the discharging rate. For actuators, this feature may be considered analogous to eccentric contraction of skeletal muscles. Since the discharge mechanism of an electrohydraulic actuator, such as the HASEL actuator, is active, not passive (which is common in the field), the actuators are able to maintain a ‘catch’ state using the described power scheme, whereby they actuate and hold a position without consuming much energy. The circuitry described herein provides active discharge without requiring a large resistor connected in parallel with the actuator. That is, discharging of electrostatic or electrohydraulic actuators is generally a passive process accomplished by placing a large resistor in parallel with the actuator. The large resistor can limit bandwidth, increase steady state power draw, and limit the benefits of the “catch” state of the actuator, as the actuator would constantly be discharging through the resistor rather than holding its charge. Such a scheme further enables the implementation of compact multichannel high voltage power supplies, since only one HV amplifier (typically the largest electrical component) is required and each HV switch may be small. Since the actuators described herein primarily consume power only when charging and release power when discharging, the control signals of the charging and discharging switches may be programmed to power the switches in sequences that match the charging and/or discharging current profiles of the actuators used in the overall system. In other words, each switch is only powered for the duration in which the associated actuator is charging or discharging, thereby reducing the power consumption of the entire array of switching elements.

FIG.11illustrates examples of motion profiles of HASEL actuators which may be achieved using HV power supply1000ofFIG.10. The four plots inFIG.11show displacement as a function of time. Actuation profiles for HASEL actuators may be square (as shown in first plot1110) with varying slew rate, amplitude, and frequency (as represented by actuation profiles indicated by brackets1111,1112,1114,1116, and1118). Waveforms may be combined to create unique actuation profiles. For example, a square wave may be combined with a sinusoidal waveform (as shown in second plot1120and represented by the actuation profile indicated by a bracket1122) to provide large displacement and vibration feedback. Similarly, stepped displacement profiles may be achieved (as represented by actuation profile indicated by bracket1124). Other common possibilities include triangle waveforms (as shown in third plot1130) and sinusoidal waveforms (as shown in fourth plot1140) with constant or varying amplitude and frequency. Importantly, any of these displacement profiles may be superimposed to achieve essentially arbitrary displacement profiles. Such flexibility in actuation profiles is achievable due in part to the unique actuation properties of HASEL actuators, in which voltage is directly coupled with shape change of the actuator structure, as well as the high level of control that can be achieved with HV power supply1000ofFIG.10.

FIGS.12A and12Billustrate how a HASEL actuator may be used a sensor. As an example, the structure of a HASEL actuator1200may function as a variable capacitor, where the electrodes of the HASEL actuator function as the electrodes of a parallel plate capacitor. The multi-layered structure of dielectric films and dielectric liquid separating the electrodes function as the dielectric of a typical parallel plate capacitor. The capacitance outside of the zipped length of the electrodes (i.e., capacitance in the expanded portion of the actuator containing the dielectric fluid) is essentially negligible.

To demonstrate how this structure can function as a sensor,FIG.12Ashows a HASEL actuator1200with an applied voltage V which causes the electrodes to fully zip together. In this state the flexible shell portion of HASEL actuator1200has expanded to a thickness1206. Optionally, a plate1208may be positioned on top of the actuator to help transmit an external force to the actuator. When a user1210applies a force to the actuator, optionally through plate1208as shown inFIG.12B, while the applied voltage V remains constant, the actuator exhibits a reduced thickness1206′. Due to the applied force, the dielectric fluid within the flexible shell is pushed back toward the electrodes to partially unzip the electrodes apart, thus reducing the capacitance of the pair of electrodes. This change in capacitance may be detected, for instance, by monitoring the impedance of the actuator using various methods known in the art. As an option, the sensing behavior may be calibrated so that capacitance may be measurable as a function of applied voltage1202, zipped length of the electrodes, and/or actuator thickness. Such a functionality may be leveraged for a variety of applications such as, but not limited to, providing closed loop control for precise and controlled actuation, analog or binary signal generation for sensing of proximity or touch, and as part of a combination sensor in conjunction with an external sensor, such as force sensitive resistors, optical sensors, and/or fabric sensors.

FIG.13illustrates the interior of an automobile including several HASEL actuators integrated into many surfaces and interfaces that with which drivers and passengers interact, in accordance with certain embodiments. For instance, a driver's seat1300has been fitted with HASEL actuators in several locations. Seat cushion1310has an array of HASEL actuators1312embedded therein. Actuators in the seat cushion can serve many functions such as, but not limited to: 1) providing a massage for the user; 2) adjusting the seat shape to reduce driver fatigue or pain points; and 3) providing vibration for notifications or entertainment. Similarly, seat bolsters1320may be integrated with an array1322of actuators for providing tactile sensation and/or seat adjustments for a driver's back and sides.

Similar actuator integrations may be applied to any of the other seats within the automobile. For instance, any seat back1330may be provided with encapsulated arrays of actuators1332, either integrated into the internal surface of the seat back or as an external addition, to provide massage, vibration, and/or seat adjustment functions. In an example, encapsulated sheets of actuators may provide ease of installation within the seat assembly, as a sheet of HASEL actuators may be easily placed between the seat cover and cushion with simple mechanical connection points (e.g., an adhesive, snaps, and/or hook-and-loop attachments) and a single cable bundle that connects to a HV power supply and the vehicle control unit. Such a system may be integrated with any seat or surface within the vehicle. Further, actuators1340integrated into the headrest may provide vibration for massage, haptic responses for notifications, and can produce movements that are synchronized with music or other entertainment in the car.

In addition, HASEL actuators integrated into an automotive seat may simultaneously function as sensors. For example, the actuators may be used to sense the size, weight, and/or location of a passenger to adjust air vent direction and airbag activation. Using an array of HASEL sensors integrated into various areas of the automotive seat, typical passengers or drivers may be recognized based on their size and/or weight. This information may be used to determine correct seat position, mirror position, airbags, vent direction for climate systems, and suggested routes for navigation, such as suggesting the quickest route for a typical morning destination for a particular driver. Sensors may also be used to detect when someone has been sitting or driving too long and cause the passenger or driver to suggest a break by, for example, providing a vibration signal.

Beyond seating applications, many surfaces that a user touches may utilize HASEL actuators. For instance, HASEL actuators can be incorporated to surfaces to act as buttons that appear on demand, such as using the encapsulated actuator array shown inFIG.9. Such “buttons-on-demand” may normally be disguised as a completely flat surface and may pop-up when a user is in close proximity to the surface, thus reducing the number of static buttons on a center console1350, arm rests1352, dashboard1354, and steering wheel1356for more aesthetically pleasing appearance and fewer distractions for drivers and passengers. Further, HASEL actuators used as buttons-on-demand may simultaneously act as sensors to collect user input to replace buttons and other control features typically found in a vehicle (e.g., navigation, radio, entertainment, signaling, and ignition, to name a few examples). Optionally, a control system1390, such as the onboard computer of an automobile or a dedicated processing system for interfacing between the onboard computer of a vehicle and the various actuator systems integrated into the vehicle, may be used to provide centralized control of the actuators and actuator arrays used with the vehicle. As an example, the control system may control the activation of specific actuator functions according to user input from a central user interface in the vehicle.

WhileFIG.13illustrates use of these systems in an automobile, it should be appreciated that these features could be useful for a variety of vehicles, transportation modalities, as well as stationary seating systems, such as gaming seats, sofas, and seats used in simulators and training systems.

FIG.14shows a detailed illustration of a seat1400containing multiple arrays of HASEL actuators, in accordance with certain embodiments. For example, arrays of actuators14020of varying sizes may be integrated into seat cushion1404, bolster1408, and head rest1410. Similarly, encapsulated arrays of actuators1420may be distributed about the seat such as in lower seat back1424and upper seat back1426. It should be appreciated that any of the locations showing arrays of actuators may contain encapsulated arrays of actuators, and vice versa. Further, arrays of actuators contained within an encapsulating shell (e.g., as shown inFIG.9) may be integrated into the structure or into a surface covering of seat1400(e.g., within the seat cushion, bolster, or head rest), or separately attached to any surface within an automobile using an attachment mechanism such as, but not limited to, adhesives, tape, belts, hooks, snaps, and hook-and-loop attachments.

FIG.14also shows multiple buttons-on-demand located on side1430of seat1400. In an example, one button1432is deactivated so that the surface is essentially flat. Another button1436is activated to present as a raised surface. Conversely, a recessed button1438may be created by configuring the actuator integrated therein to pull into the surface at rest or upon activation. These buttons may be used, for example, to control seat position or activate other in car features such as navigation, heated seats, and/or activate massage functions in the seat, among others.

FIG.15shows a possible feedback loop for actuator systems for interacting with a user to provide tactile feedback and sensation. The feedback loop ofFIG.15begins with an input signal1500which is sent to a vehicle control unit1502. Vehicle control unit1502in turn sends a signal to a HV power supply (shown in this example as a multi-channel HVPS1504), which provides a signal (e.g., power output) to an array of actuators1506. Array of actuators1506provides a signal, in the form of a displacement, movement, or tactile feedback1508with which a user1510may interact. The user may then provide some force and displacement to the actuator which would result in a change of capacitance that would be detected by a capacitance sensing unit1512. Capacitance sensing unit1512sends a signal related to the detected capacitance change to a force and/or displacement unit1514, which in turn may provide a feedback signal1516toward vehicle control unit1502. It should be noted that force and/or displacement unit1514optionally calculates and provides calibrated data related to the sensed capacitance change to be integrated with any new input signal provided to vehicle control unit1502.

FIGS.16A and16Billustrate the exemplary operations of a surface containing several buttons on demand.FIG.16Ashows a flat, encapsulated actuator surface1600before a user's hand1602comes into contact with the encapsulated actuator surface. As an example, as the user's hand comes into contact or close proximity with encapsulated actuator surface1600, the self-sensing capability of the encapsulated actuators or external sensors may detect the user. Upon detection of the user's hand nearby or in contact with the encapsulated actuator surface, the actuators contained within the encapsulated actuator surface may be caused to expand, such that buttons1606,1608,1610, and1612protrude from encapsulated actuator surface1600′, as shown inFIG.16B. These “buttons on demand” may be configured to sense a user's touch to relay a signal to the electronic system controlling the buttons and/or provide tactile feedback to the user. Tactile feedback may include, for example, a haptic response such as an emulated button click or a vibration signal.

FIG.17illustrates a button-on-demand system1700based on expanding HASEL actuators suitable for use as part of encapsulated actuator surface1600, in accordance with an embodiment. Button-on-demand system1700is presented as a flat, surface1702in a top view on the left ofFIG.17. A cross-section A-A on the right ofFIG.17shows various components underneath surface1702. Surface1702may be formed of an elastic, stretchable or flexible material, a multiple layers of materials, or a variety of materials, depending on the desired mechanical properties. Optionally, surface1702may be textured to emulate leather or other natural materials typically found in a vehicle interior. One or more HASEL actuators1710are encapsulated within button-on-demand system1700. In an example, the one or more HASEL actuators may be sandwiched between a top plate1720and a bottom plate1722to aid in transmitting and/or distributing the force produced by the actuator when activated. Surface1702may optionally provide a restoring or compressive force to hold the actuator in place. Optionally, additional restoring force may be provided by a spring element1730such as an elastic band. In the example shown inFIG.17, the one or more actuators are encapsulated in a pocket within button-on-demand system1700so that surface1702is flat in an inactive state.

FIG.18illustrates an activated, button-on-demand system1700′, in which the one or more actuators encapsulated within the system has been activated such that surface1702′ now includes a raised button1802. As visible in cross-section A-A, activated HASEL actuators1710′ expand, causing button1802to protrude from surface1702′. The raised height of button1802may be varied based on the applied voltage to the one or more actuators1710′, as an example. Although a rectangular shape is shown for raised button1802, it should be appreciated that other button shapes are also contemplated and are considered a part of the present disclosure. Once activated, raised button1802provides tactile and/or visual cues to aid users in locating and interacting with the button. Optionally, button-on-demand system may include, for example, a light emitting diode (LED) or another small light source to light up the raised button, providing an additional visual indication of the activation of the button-on-demand. As another option, the activation of the actuator may cause the surface of raised button1802to be modified (e.g., imbued with a new texture or heated) as another indication of the button activation.

The systems described so far rely on HASEL actuators directly interacting with a user to provide tactile sensations or change shape of a surface. Alternatively, one or more HASEL actuators may also be used to indirectly control surfaces within automobile interiors. For example, traditional systems used in vehicles to modify the configuration of seat cushions and other equipment rely on inflatable bladders, in which the size of the bladders is controlled by pressurized air generated by a pump and controlled by systems of valves that modify the flow of air in and out of the bladders. Such pumps are generally driven by electric motors, and the valves are activated by a variety of technologies such as solenoids and piezoelectric actuator systems. HASEL actuators provide an advantageous alternative for both pumps and valves.

FIG.19illustrates a front view1900and a cross-sectional view1902of a seat containing a traditional inflatable bladder for lumbar adjustment. When empty, the bladder sits flat and a user in the seat is supported mostly by the seat cushion. Inflating a bladder1912changes the shape of the seat back and can provide more support for a user and may be adjustable to fit the needs and comfort of different drivers or passengers. In an example a tube1926leading from bladder1912connects to a valve block1928. Valve block1928modulates the flow of air from a pump1930and vents air contained in bladder1912. As shown inFIG.19, HASEL actuators may be used to replace valve block1928and pump1930. In other embodiments, HASEL actuators may also be used in place of bladder1912.

FIG.20shows a diaphragm pump2000which uses HASEL actuator to control fluid flow. The pump includes an actuator2001including a flexible dielectric film pouch filled with a dielectric fluid. The pump further includes a housing2002surrounding actuator2001, and a chamber2004which is separated from actuator2001by a diaphragm2003. Chamber2004is fluidly coupled with an inlet channel2006and an outlet channel2008. A first one-way valve2012is disposed between inlet channel2006and chamber2004, and a second one-way valve2016is disposed between chamber2004and outlet channel2008.

Actuation process of diaphragm pump2000is shown inFIGS.21A and21B, in conjunction withFIG.20. Referring toFIG.21A, a first step of actuating pump is shown in the top left figure. A voltage ϕ2is applied to actuator2001via electrodes. As described above with respect to HASEL actuator examples, the electrodes zip together along at least a portion of their lengths, thereby pushing dielectric fluid away from the electrodes to form a more circular or bulbous pocket having an increased height compared with the off-state. The pocket engages diaphragm2003and pushes the diaphragm into chamber2014. Fluid occupying chamber is pressurized due to the membrane taking up more volume within the chamber as more voltage is applied to the actuator. The application of an even higher voltage ϕ3further increases the height of the actuator to increase the pressure on the diaphragm to a first threshold pressure (for example, a pressure greater than pressure of fluid in outlet channel2008), as shown in the top right figure. Then, one-way valve2016unseats from the pump housing and allows fluid to pass from the chamber into the outlet channel2008. At the bottom right figure, applied voltage is decreased to ϕ4and dielectric fluid flows back toward the electrodes, thereby reducing height of the actuator and reducing pressure in chamber2004. Once the pressure within chamber2004drops below a second threshold pressure (for example, the pressure of fluid in inlet channel2006), one-way valve unseats from the pump housing and allows fluid to flow from inlet channel2006into chamber2004. Diaphragm pump2000may be returned to its resting state, with the applied voltage reduced to ϕ1=0, as shown in the bottom left figure inFIG.21A.

FIG.21Bshows pressure in chamber2004as a function of volume change of chamber2004for each of the steps in the four-step pumping cycle described inFIG.21A. Data is shown for both gas and liquid fluids. For an incompressible fluid, the path from state 1 to state 2 is a vertical line because the incompressibility of the fluid prevents deformation of the diaphragm, until the outlet valve opens (state 2) and the fluid can flow out of the chamber at constant pressure (state 2 to 3). The maximum volume (state 3) is limited by either the volume of the chamber2004(i.e., all fluid is pumped out of the chamber) or by the strength of the actuator at the voltage ϕ3, which is the difference of the force exerted by the HASEL actuator and the force required to deform the diaphragms divided by the area of the diaphragm (the curve Pactuator−Pdiaphragm). For an incompressible fluid, the path from state 3 to 4 is again a vertical line. When the inlet valve is open liquid flows into the chamber at constant pressure (state 4 to 1) until the pump reaches state 1.

For a compressible fluid, the volume of the chamber changes when the fluid is pressurized. In the pressure-volume plane, the process of pressurization is represented by a curved line from state 1 to state 2′, the shape of which is determined by the behavior of the fluid (e.g., ideal gas law). The pumping phase for a compressible fluid follows the horizontal line from state 2′ to state 3. During depressurization, a compressible fluid will expand before pressure in the chamber is low enough to cause the inlet valve to open (state 4′). This transition is again determined by the compressibility of the fluid within the chamber and is represented by the curved line from state 3 to state 4′ in the pressure-volume plane. When the inlet valve is open, fluid flows into the chamber at constant pressure (state 4 to 1) until state 1 is reached.

The area enclosed by the loops 1-2-3-4 and 1-2′-3-4′ represent the mechanical work output during one pumping cycle for an incompressible and a compressible fluid, respectively. More work per cycle is expected when pumping incompressible fluids such as water than when pumping a compressible fluid such as air. When pumping compressible fluids, the shape of paths from 1 to 2′ and 3 to 4′ depends on the ratio of the volumes of states 1 and 2′, and the ratio of the volumes of state 3 and 4′. Reducing the amount of dead space within the pump chamber will increase the slope of the paths from 1 to 2′ and 3 to 4′, which will result in more work per cycle when pumping a compressible fluid. Ultimately the work per cycle for the pump may be limited by the performance of the HASEL actuator (state 3).

The valve blocks of the bladder system shown inFIG.19requires a valve block or array of valves that control the flow of fluid into and out of the bladder. Such valve blocks are used for a variety of systems both pneumatic and hydraulic. In contrast, HASEL actuators can be used to create compact valves with either binary or analog control of fluid flow.

FIG.22illustrates a valve2200that is normally closed, i.e., meaning fluid does not flow when the valve is in the off-state. The valve opening is varied using an actuator2201which includes a pouch formed by at least a dielectric layer2214and a stretchable membrane2210. The pouch is filled with liquid dielectric2204and a pair of opposing electrodes2206,2208partially covering opposing sides of the pouch. The valve is controlled by applying a voltage across the electrodes. InFIG.22A, the applied voltage V0is small enough that the electrodes do not zip together.FIG.22Adepicts the off state of the valve. Stretchable membrane2210has sufficient pressure to force the pouch against a sealing surface, which prevents flow of fluid from inlet2216to outlet2218. The pouch itself may have additional layers or coatings in select positions to improve the quality of the seal between pouch2202and outlet2218.

FIG.22Bshows the valve in an on state, where the electrodes have zipped together with a voltage V1applied thereto. As the electrodes zip together, the pressure within the pouch increases and causes stretchable membrane2210to deform. This allows the lower portion of pouch2202to lift away from outlet2218, which enables fluid to flow through outlet2218. Control of the valve may be binary (i.e., either fully open or closed) or the state of the valve may be varied continuously in order to provide a variable flow rate through outlet2218. As the pressure and stretch characteristics of the membrane will be non-linear and may exhibit snap-through instabilities, these characteristics may be leveraged to achieve rapid opening and/or closing of the valve.

FIGS.23A and23Billustrate the operations of a valve2300which is normally open, meaning fluid flows when the valve is in the off state. The valve opening is varied using a HASEL actuator2301. One side of HASEL actuator2301sits on a surface2306while the other is fitted with a rigid or semi-rigid part2302that presses against a tube2308. Tube2308contains a flowing fluid such as a gas or liquid2310. Part2302pressing against tube2308may be viewed as a clamp, which presses against tube2308to control flow. In this case, the wall of tube2308closest to HASEL actuator2301should be soft and deformable, while the opposite wall is rigid or in direct contact with a rigid surface. Part2302may be wide at the end closest to HASEL actuator2301and narrower at the end furthest from HASEL actuator2301in order to concentrate the force output of the actuator onto a smaller area. Such an approach increases the contact pressure of the actuator which increases the pressure that can be blocked by a valve. As shown inFIG.23A, when the actuator is in an off state, fluid flows freely through tube2308from left to right.FIG.23Bshows the valve after the electrodes of the HASEL actuator have zipped together due to applied voltage V1. Actuator2301′ has expanded, causing part2302to deform tube2308′. If force and displacement of the clamp are large enough, the tube will be completely closed and the flow of fluid through tube2308′ will be blocked. Because the force and displacement of HASEL actuators can be modulated by changing the applied voltage, the valve can operate at any state between fully open and fully closed.

FIG.24shows a graph of peak-to-peak displacement performance of HASEL actuators of different layer structures as a function of frequency of the sinusoidal input signal, in accordance with an embodiment. Graph2400includes curves characterizing single layer (E-0015-01), four-layer (E-0015-04), and fourteen-layer (E-0015-14) actuators, each actuator layer having a configuration shown inFIG.30, which is described at the appropriate junction below. While all of the characterized actuators are generally circular with a nominal diameter of 3 cm, larger and smaller diameters are also contemplated and are considered to be a part of this disclosure. As can be seen inFIG.24, the peak-to-peak (Pk-Pk) displacement of the actuators is nearly constant, until it starts to roll-off at 10 to 30 Hz. As expected, actuators with more layers provide more displacement.

FIG.25shows a graph of peak-to-peak acceleration performance of HASEL actuators of different layer structures (same as those evaluated inFIG.24) as a function of frequency of the sinusoidal input signal, in accordance with an embodiment. As expected, the acceleration is essentially negligible at low driving frequencies. then, all of the actuators evaluated provide significant acceleration above 1 Hz. For instance, in the example shown inFIG.25, the fourteen-layer actuator (E-0015-14) provides greater than 1 G of acceleration in the frequency range of 4-100 Hz. The thinner actuators have higher maximum acceleration (e.g., >4 G inFIG.25) and operate at a higher frequency range. The higher frequency range of the single and four-layer actuators is likely enabled by the fact that each actuator presents a smaller electrical load on the power supply compared to the 14-layer actuator. That is, in cases where acceleration is more important than displacement, smaller actuator stacks may be preferable. Further, the range of performance as illustrated inFIGS.24and25highlights the ability to tune haptic performance with different actuator sizes.

FIG.26shows a graph of static force performance of HASEL actuators of different layer structures as a function of actuator stroke, in accordance with an embodiment. As shown inFIG.26, force output varies with stroke, starting with a maximum force (blocked force) at zero stroke and decreasing at higher stroke. Different actuator system parameters, such as actuator size (i.e., diameter in the case of the actuator systems evaluated inFIGS.24-26), the number of actuators in each stack, and the number of actuator stacks operated in parallel to meet the specific performance and size requirements of an application.

Actuator response time is another important factor for effectively transmitting haptic information. For low latency communication, the actuator should have a short response time to a changing input signal. Additionally, a short response time relates back to the actuator acceleration, as humans are more sensitive to haptic signals at higher acceleration.

FIG.27shows a graph of actuator response time overlaid on the square wave input voltage applied to the actuator, in accordance with an embodiment. The HASEL actuator configurations used with the embodiments described herein feature direct electrical control of the actuation with fast turn-on and turn-off times, as shown in graph2700. Both turn-on and turn-off times are quite fast for the actuator. This dynamic performance allows for precise timing of haptic information and provides a crisp actuation feel to the user.

It is noted that, while the above described examples describe expanding actuators, contracting actuators may also be utilized in certain applications, such as for kinesthetic haptic feedback. Additionally, other actuator geometries can be made to provide optimal performance for a specific application.FIGS.28-32show HASEL actuators of various shapes and sizes, suitable for use as haptic actuators in accordance with certain embodiments.

FIG.28shows an actuator system2800including a plurality of pouches2810, each pouch containing a fluid dielectric2812therein, in accordance with an embodiment. Each pouch is sandwiched between a pair of electrodes (only top electrodes2820are visible inFIG.28). A top connection2822extends from each top electrode2820, and a bottom connection2824extends from the bottom electrode (not visible inFIG.28). Each one of top connection2822and bottom connection2824is further connected with an electrical coupling2830, onto which an external power source may be connected to electrically address each pouch within actuator system2800. pouches, electrodes, and connections may optionally be held together by a skirt2840. In an embodiment, skirt2840may function as an encapsulating layer to provide electrical insulation, thermal insulation, cushioning, and/or electrical isolation between each actuator pouch in actuator system2800. Actuator system2800may be suitable, for example, for applications requiring a plurality of actuators disposed close together, such as for access by individual fingers within a glove.

FIG.29shows an alternative actuator system2900including a pouch2910containing a fluid dielectric2912therein, in accordance with an embodiment. Pouch2910is sandwiched between a pair of electrodes (only top electrode2920is visible inFIG.29). A top connection2922extends from top electrode2820, and a bottom connection2924extends from the bottom electrode (not visible inFIG.29). Top connection2922and bottom connection2924is further connected with electrical couplings2930, provide electrical access from an external power supply, for example. As shown inFIG.29, a skirt2940surrounds the pouch, electrodes, and connections. Actuator system2900is similar to actuator400shown inFIG.4.

FIG.30illustrates still another embodiment of an actuator system3000. As shown inFIG.30, actuator system3000including a pouch3010containing a fluid dielectric3012therein. Pouch3010is sandwiched between a pair of electrodes (only top electrode3020is visible inFIG.30). A top connection3022extends from top electrode3020, and a bottom connection3024extends from the bottom electrode (again, not visible inFIG.30). An end portion of each one of top connection3022and bottom connection3024is exposed to form an electrical coupling3030, onto which an external power source may be connected to electrically address actuator system3000. The entire actuator system, except for electrical couplings3030, may optionally be encapsulated by a skirt3040.

A two-pouch version of an actuator system is shown inFIG.31, in accordance with an embodiment. As shown inFIG.31, an actuator system3100includes a first pouch3110A and a second pouch3110B, each filled with fluid dielectric3112. While first and second pouches3110A and3110B are shown adjacent to each other, the pouches may be spaced apart, in certain embodiments. Again, each pouch is sandwiched between a pair of electrodes (only top electrodes3120A and3120B are visible inFIG.31). A top connection3122extends from each top electrode3120, and a bottom connection3124extends from the bottom electrode (not visible inFIG.31). In the embodiment illustrated inFIG.31, top connection3122is shown to be connected to both of the top electrodes3120A and3120B, and bottom connection3124is connected with the bottom electrodes on both pouches. A portion of top and bottom connections3122and3124may be exposed to enable electrical coupling with an external power source. In the illustrated embodiment, actuator system3100further includes a skirt3140surrounding the entire structure, except portions of top and bottom connections3122and3124intended to provide electrical access.

Still another exemplary embodiment of an actuator system is shown inFIG.32. As shown inFIG.32, an actuator system3200includes an elongated pouch3210filled with a fluid dielectric3212. A portion of elongated pouch3210is sandwiched between a pair of electrodes (again, only top electrode3220is visible). A top connection3222extends from top electrode3220, and a bottom connection3224extends from the bottom electrode (not visible) to enable electrical access to an external power supply. Actuator system3200may further includes a skirt3240surrounding the entire structure, except portions of top and bottom connections intended to interface with the external power supply.

While a variety of shapes of actuators are illustrated herein, still additional variations of actuator system shapes, pouch shapes, electrode shapes, and array arrangements (e.g., honeycomb array, offset row arrays, square arrays, and more) are contemplated and considered a part of the present disclosure. For instance, thinner pouch arrangements may be suitable for certain applications, while different widths or lengths of electrodes may be more suitable for certain applications. Different combinations of pouch shapes and electrode shapes may also be tailored for specific applications requiring, for example, fast switching or particularly high voltages.

As used herein, the recitation of “at least one of A, B and C” is intended to mean “either A, B, C or any combination of A, B and C.” The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. Each of the various elements disclosed herein may be achieved in a variety of manners. This disclosure should be understood to encompass each such variation, be it a variation of an embodiment of any apparatus embodiment, a method or process embodiment, or even merely a variation of any element of these. Particularly, it should be understood that the words for each element may be expressed by equivalent apparatus terms or method terms-even if only the function or result is the same. Such equivalent, broader, or even more generic terms should be considered to be encompassed in the description of each element or action. Such terms can be substituted where desired to make explicit the implicitly broad coverage to which this invention is entitled.

As but one example, it should be understood that all action may be expressed as a means for taking that action or as an element which causes that action. Similarly, each physical element disclosed should be understood to encompass a disclosure of the action which that physical element facilitates. Regarding this last aspect, by way of example only, the disclosure of a “protrusion” should be understood to encompass disclosure of the act of “protruding”—whether explicitly discussed or not—and, conversely, were there only disclosure of the act of “protruding”, such a disclosure should be understood to encompass disclosure of a “protrusion”. Such changes and alternative terms are to be understood to be explicitly included in the description.