Bistable dielectric elastomer actuators and multistable dielectric elastomer actuators
By using bistable and multistable dielectric elastomer actuators and taking advantage of the properties of low-melting-point alloys and dielectric elastomers, multiple deformations and multiple degrees of freedom functions of soft mechanical grippers are realized, solving the problem of narrow applicability in existing technologies and enhancing the applicability and ease of control of the gripper.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TAIYUAN UNIVERSITY OF TECHNOLOGY
- Filing Date
- 2023-11-21
- Publication Date
- 2026-07-31
AI Technical Summary
Existing soft mechanical grippers cannot simultaneously achieve variable stiffness and multiple degrees of freedom, thus limiting their applicability.
Bistable and multistable dielectric elastomer actuators are employed, utilizing the properties of low-melting-point alloys and dielectric elastomers. Through low-current and high-voltage control, combined with a constraint structure, various deformations of the actuators are achieved, including curling and bending.
It enables multiple gripping postures of the soft mechanical gripper, increasing its applicability. The control process is simple, suitable for harsh scenarios, and has variable stiffness and multiple degrees of freedom.
Smart Images
Figure CN117283607B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of soft robot technology, and more particularly to a bistable dielectric elastomer actuator and a multistable dielectric elastomer actuator. Background Technology
[0002] Soft mechanical grippers are mechanical devices constructed from flexible materials that can continuously deform. They mimic the softness and agility of living organisms, offering greater safety and adaptability compared to traditional rigid mechanical devices. They provide significant advantages in confined spaces, complex object grasping, and human-machine interaction. Dielectric elastomers, with their high energy density, rapid response, and significant deformation, have become a major research focus in the field of soft mechanical grippers. With continuous societal development, the demand for soft mechanical devices is increasingly evident, and dielectric elastomer actuators have broad application prospects in rehabilitation, detection, and rescue fields.
[0003] The working methods of soft mechanical grippers on the market are relatively simple, highly targeted, and have a narrow range of applications. They are difficult to achieve both variable stiffness and multiple degrees of freedom at the same time. Summary of the Invention
[0004] To overcome the technical shortcomings of existing soft mechanical grippers that cannot simultaneously achieve variable stiffness and multiple degrees of freedom, this invention provides a bistable dielectric elastomer actuator and a multistable dielectric elastomer actuator.
[0005] This invention provides a bistable dielectric elastomer actuator, comprising a driving structure and a constraint structure. The constraint structure includes an unstretched rectangular dielectric elastomer film and a non-expandable layer. A long U-shaped groove is formed on the front side of the unstretched rectangular dielectric elastomer film, the length direction of which is aligned with the length direction of the film, and the groove is located at the midpoint of the film's width. The U-shaped groove is filled with a low-melting-point alloy. The non-expandable layer is adhered to the back side of the unstretched rectangular dielectric elastomer film. The driving structure includes a pre-stretched rectangular dielectric elastomer film, two first flexible electrodes, and one second flexible electrode. The dielectric elastomer rectangular film is a dielectric elastomer initially stretched to elastic deformation in both the length and width directions, with the tensile force in the length direction being greater than that in the width direction. Two first flexible electrodes are located on the unstretched dielectric elastomer rectangular film on both sides of the U-shaped groove, and the two first flexible electrodes are connected to the low melting point alloy in the U-shaped groove through wires. The pre-stretched dielectric elastomer rectangular film is pasted to the front side of the unstretched dielectric elastomer rectangular film, with the two first flexible electrodes sandwiched between them. The second flexible electrode is pasted to the outer surface of the pre-stretched dielectric elastomer rectangular film, and the second flexible electrode corresponds to the two first flexible electrodes.
[0006] The drive structure is the power source for the actuator, controlling the deformation of the brake. The constraint structure limits the deformation of the actuator and, together with the drive structure, controls the movement of the actuator. The U-shaped groove is a low-melting-point alloy channel. Utilizing the solid-liquid transition characteristics of the low-melting-point alloy, different functions of the actuator are achieved. When the low-melting-point alloy is connected to a low-voltage current through two first flexible electrodes (i.e., when the two first flexible electrodes are connected to the live wire and neutral wire of the power supply respectively and a low current is input, the low current range is 1~2A, which is within the safe range), the first flexible electrodes, the live wire, the neutral wire, and the low-melting-point alloy form a closed circuit. The low-melting-point alloy generates a certain Joule heat, thus changing from a solid to a liquid state. When the low-voltage current is disconnected, the low-melting-point alloy will return from the liquid state to the solid state. When the low-melting-point alloy is in the solid state, it will limit the unstretched dielectric elastomer rectangular film from curling and deforming along its length. The pre-stretched rectangular dielectric elastomer film is made of dielectric elastomer. A key characteristic of dielectric elastomers is that when a high driving voltage is applied externally (a high voltage is applied to the second flexible electrode, creating a high voltage difference between the second and first flexible electrodes; this high voltage difference is the driving voltage, which is protected against energization to ensure user safety), the thickness of the dielectric elastomer film decreases, and its area increases, thus achieving deformation. Under the constraint of a non-expandable layer, the stress on the plane of the dielectric elastomer film is converted into torque, causing the film to change from in-plane contraction to out-of-plane bending. When the low-melting-point alloy is solid, it restricts the movement of the unstretched dielectric elastomer rectangular film along its length. Therefore, the pre-stretched dielectric elastomer rectangular film causes the unstretched dielectric elastomer rectangular film to curl inward along its width. When the low-melting-point alloy is liquid, the unstretched dielectric elastomer rectangular film can deform under the traction of the pre-stretched dielectric elastomer rectangular film. Since the basic tensile force in the length direction of the pre-stretched dielectric elastomer rectangular film is greater than the basic tensile force in the width direction, the unstretched dielectric elastomer rectangular film will only preferentially curl along its length under the drive of the pre-stretched dielectric elastomer rectangular film. Specifically, the wire connecting the first flexible electrode and the low-melting-point alloy is a conductive silver wire. The second flexible electrode corresponding to the two first flexible electrodes means that the edges of the two first flexible electrodes are considered as a whole, and the edges of this whole are aligned with the long and wide edges of the second flexible electrode.
[0007] Preferably, symmetrical cuts perpendicular to the length direction are made on the two long sides of the unstretched dielectric elastomer rectangular film. The two cuts are located at the bottom of the unstretched dielectric elastomer rectangular film. The size of the prestretched dielectric elastomer rectangular film is equal to the size of the plate above the cuts of the unstretched dielectric elastomer rectangular film. The second flexible electrode is located inside the plate of the prestretched dielectric elastomer rectangular film, and the area of the second flexible electrode is slightly smaller than the area of the prestretched dielectric elastomer rectangular film. As is easily understood, the two cuts do not completely divide the unstretched rectangular dielectric elastomer film into two parts; the unstretched rectangular dielectric elastomer film remains a single unit. The portion above the cuts serves as the movable part of the unstretched rectangular dielectric elastomer film, while the portion below the cuts serves as the fixed part. The dimensions of the pre-stretched rectangular dielectric elastomer film are consistent with the dimensions of the movable part of the unstretched rectangular dielectric elastomer film. Therefore, the pre-stretched rectangular dielectric elastomer film can completely cover the movable part of the unstretched rectangular dielectric elastomer film. This is so that the pre-stretched rectangular dielectric elastomer film, acting as the driving structure, only drives the deformation of the movable part that completely covers the unstretched rectangular dielectric elastomer film without affecting its fixed part. The area of the second flexible electrode is slightly smaller than the area of the pre-stretched rectangular dielectric elastomer film, meaning that both the length and width edges of the second flexible electrode are recessed inward by 3-5 mm. This allows the corresponding areas of the second and first flexible electrodes to cover most of the area of the pre-stretched rectangular dielectric elastomer film. The reserved space at the edge serves two main purposes: first, it makes the deformation at the edge more obvious; second, it prevents the edges of the first and second flexible electrodes from directly crossing the pre-stretched dielectric elastomer rectangular film and causing air breakdown after a high-voltage electric field is applied.
[0008] Preferably, the non-expandable layer is a thin film tape.
[0009] This invention also provides another multistable dielectric elastomer actuator, comprising two non-expandable layers and a square driving structure. The driving structure includes two corresponding square flexible electrodes and a pre-stretched dielectric elastomer square film stretched proportionally in both the length and width directions. The two corresponding square flexible electrodes are respectively attached to the middle of the two sides of the pre-stretched dielectric elastomer square film. The area of the square flexible electrodes is smaller than the side area of the pre-stretched dielectric elastomer square film. The portions of the two sides of the pre-stretched dielectric elastomer square film not covered by the square flexible electrodes are respectively attached with square annular non-expandable layers. The non-expandable layer located on the front side of the pre-stretched dielectric elastomer square film has notches in the middle of the four sides, and shape memory alloy layers or shape memory polymer layers are disposed in the notches. A high voltage differential is applied to the square flexible electrodes on both sides of the pre-stretched dielectric elastomer square film, driving the pre-stretched dielectric elastomer square film to deform. The pre-stretched dielectric elastomer square film is stretched proportionally to ensure that the stress in both the length and width directions of the square is equal. Shape memory alloy layers or shape memory polymer layers are placed at the four notches. When a low current is passed through the shape memory alloy layer or shape memory polymer layer, it can deform. It can either deform along with the pre-stretched dielectric elastomer square film or restrict its deformation at the corresponding positions. The principle is the same as that of the previous bistable dielectric elastomer actuator. The overall shape change of the actuator is controlled by controlling the modulus change of the shape memory alloy layer or shape memory polymer layer at the four positions.
[0010] Preferably, a notch is provided in the middle of each of the four sides of the non-expandable layer located on the back side of the pre-stretched dielectric elastomer square film, and a shape memory alloy layer or a shape memory polymer layer is disposed in the notch. Similarly, since this structure uses proportional stretching, the same function can be achieved on both sides. When four notches are provided in the non-expandable layer on the back side, the actuator as a whole can achieve more shape changes by controlling the modulus changes of the shape memory alloy layer or shape memory polymer layer at eight positions.
[0011] Compared with the prior art, the technical solution provided by this invention has the following advantages: The actuator of this invention has a simple structure. As a soft mechanical gripper, it can change to a variety of different gripping postures. It is relatively easy to manufacture and has a small overall space ratio, making it suitable for more demanding scenarios and highly practical. Moreover, this invention controls the actuator through low-current heating and high-voltage control, which simplifies the control process. The soft mechanical gripper adopts a bistable structure with variable stiffness, and can change its shape to achieve different functions through different control methods during use, effectively increasing its applicability. Attached Figure Description
[0012] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.
[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0014] Figure 1 This is a schematic diagram of the initial state of a bistable dielectric elastomer actuator as described in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the second state of a bistable dielectric elastomer actuator according to a certain embodiment of the present invention; Figure 3 This is a schematic diagram of the third state of a bistable dielectric elastomer actuator according to a certain embodiment of the present invention; Figure 4 This is a schematic diagram of the fourth state of a bistable dielectric elastomer actuator according to a certain embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of a multistable dielectric elastomer actuator as described in Embodiment 2 of the present invention (where the non-expandable layer on the front side is provided with four notches). Figure 6 This is a schematic diagram of another structure of a multistable dielectric elastomer actuator as described in Embodiment 2 of the present invention (where four notches are provided in the non-expandable layers on the front and back sides, respectively). Figure 7 This is a schematic diagram of the exploded structure of a bistable dielectric elastomer actuator as described in Embodiment 1 of the present invention; Figure 8 This is the external power supply wiring diagram for a bistable dielectric elastomer actuator described in Embodiment 1 of the present invention; Figure 9 for Figure 5 Exploded view; Figure 10 for Figure 6 Exploded view.
[0015] In the figure: 1. Non-expandable layer; 2. Unstretched rectangular dielectric elastomer film; 3. First flexible electrode; 4. Prestretched rectangular dielectric elastomer film; 5. Second flexible electrode; 6. U-shaped groove; 7. Cutout; 8. Notch; 9. Square flexible electrode; 10. Prestretched square dielectric elastomer film. Detailed Implementation
[0016] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.
[0017] In this description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. It should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joint" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.
[0018] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.
[0019] The following is in conjunction with the appendix Figures 1 to 10 Specific embodiments of the present invention will be described in detail below.
[0020] In Example 1, as Figure 7 As shown, a bistable dielectric elastomer actuator is disclosed, including a driving structure and a constraint structure. The constraint structure includes an unstretched rectangular dielectric elastomer film 2 and a non-expandable layer 1. A long U-shaped groove 6 is formed on the front side of the unstretched rectangular dielectric elastomer film 2, with the length direction of the U-shaped groove 6 aligned with the length direction of the unstretched rectangular dielectric elastomer film 2 and located at the middle of the width direction of the unstretched rectangular dielectric elastomer film 2. The U-shaped groove 6 is filled with a low-melting-point alloy. The non-expandable layer 1 is adhered to the back side of the unstretched rectangular dielectric elastomer film 2. The driving structure includes a pre-stretched rectangular dielectric elastomer film 4, two first flexible electrodes 3, and one second flexible electrode 5. The dielectric elastomer rectangular film 4 is initially a dielectric elastomer stretched to elastic deformation in both the length and width directions, with the stretching force in the length direction being greater than that in the width direction. Two first flexible electrodes 3 are located on the unstretched dielectric elastomer rectangular film 2 on both sides of the U-shaped groove 6, and the two first flexible electrodes 3 are connected to the low melting point alloy in the U-shaped groove 6 through wires. The pre-stretched dielectric elastomer rectangular film 4 is pasted to the front side of the unstretched dielectric elastomer rectangular film 2, with the two first flexible electrodes 3 sandwiched between them. The second flexible electrode 5 is pasted to the outer surface of the pre-stretched dielectric elastomer rectangular film 4, and the second flexible electrode 5 corresponds to the two first flexible electrodes 3.
[0021] The actuator is a flexible structure. The drive structure is the power source for the actuator, controlling its deformation, while the constraint structure limits the deformation and, together with the drive structure, controls the actuator's movement. The U-shaped groove 6 is a low-melting-point alloy channel. The low-melting-point alloy (LMPA) is a phase change material that exhibits both good variable stiffness characteristics and high conductivity. In this embodiment, the low-melting-point alloy used is a tin-indium-bismuth alloy with a melting point of 38°C. Utilizing the solid-liquid phase transition characteristics of the low-melting-point alloy, different functions of the actuator are achieved. In this embodiment, the external wiring diagram of the bistable dielectric elastomer actuator is as follows: Figure 8 As shown, when the low-melting-point alloy is connected to a low-voltage current through the two first flexible electrodes 3, that is, when the two first flexible electrodes 3 are respectively connected to the live wire and the neutral wire of the power supply and a low current is input, the range of the low current is 0~2A, which is within the safe range; the first flexible electrodes 3, the live wire, the neutral wire and the low-melting-point alloy form a closed circuit, and the low-melting-point alloy generates a certain Joule heat, so it changes from solid to liquid. When the low-voltage current is disconnected, the low-melting-point alloy will return from the liquid state to the solid state. When the low-melting-point alloy is solid, it will restrict the unstretched dielectric elastomer rectangular film 2 from curling and deforming in its length direction. The pre-stretched rectangular dielectric elastomer film 4 is made of dielectric elastomer. The dielectric elastomer's inherent characteristic is that when a high driving voltage is applied externally (a high voltage is applied to the second flexible electrode 5, creating a high voltage difference between the second flexible electrode 5 and the first flexible electrode 3, which is the driving high voltage, ranging from 0 to 8KV), the thickness of the dielectric elastomer film decreases, thus increasing its area and achieving deformation. Under the constraint of the non-expandable layer 1, the stress on the plane of the dielectric elastomer film is converted into torque, causing the elastomer film to change from in-plane contraction to out-of-plane bending. When the low-melting-point alloy is solid, it limits the unstretched rectangular dielectric elastomer film 2 in its... The pre-stretched rectangular dielectric elastomer film 4 moves along the length direction, causing the unstretched rectangular dielectric elastomer film 2 to curl inwards along its width direction. When the low-melting-point alloy is liquid, the unstretched rectangular dielectric elastomer film 2 can deform under the traction of the pre-stretched rectangular dielectric elastomer film 4. Since the basic tensile force in the length direction of the pre-stretched rectangular dielectric elastomer film 4 is greater than the basic tensile force in the width direction, the unstretched rectangular dielectric elastomer film 2 will only preferentially curl along the length direction under the drive of the pre-stretched rectangular dielectric elastomer film 4. Specifically, the wire connecting the first flexible electrode 3 and the low-melting-point alloy is a conductive silver wire. The second flexible electrode 5 corresponding to the two first flexible electrodes 3 means that the two first flexible electrodes 3 are considered as a whole, and the edge of this whole is aligned with the long and wide edges of the second flexible electrode 5.
[0022] Based on the above embodiment 1, in a preferred embodiment, symmetrical cuts 7 perpendicular to the length direction are made on the two long sides of the unstretched dielectric elastomer rectangular film 2. The two cuts 7 are located at the lower part of the unstretched dielectric elastomer rectangular film 2. The size of the prestretched dielectric elastomer rectangular film 4 is equal to the size of the plate above the cuts 7 of the unstretched dielectric elastomer rectangular film 2. The second flexible electrode 5 is located inside the plate of the prestretched dielectric elastomer rectangular film 4. The area of the second flexible electrode 5 is slightly smaller than the area of the prestretched dielectric elastomer rectangular film 4. As is easily understood, the two cuts 7 do not completely divide the unstretched rectangular dielectric elastomer film 2 into two parts. The unstretched rectangular dielectric elastomer film 2 remains a single unit. The upper part of the cut 7 serves as the movable part of the unstretched rectangular dielectric elastomer film 2, and the two corners of the movable part of the unstretched rectangular dielectric elastomer film 2 near the cut 7 can be chamfered. The lower part of the cut 7 serves as the fixed part of the unstretched rectangular dielectric elastomer film 2. The size of the pre-stretched rectangular dielectric elastomer film 4 is consistent with the size of the movable part of the unstretched rectangular dielectric elastomer film 2. Thus, the pre-stretched rectangular dielectric elastomer film 4 can completely cover the movable part of the unstretched rectangular dielectric elastomer film 2. This is so that the pre-stretched rectangular dielectric elastomer film 4, as a driving structure, only drives the movable part that can completely cover the unstretched rectangular dielectric elastomer film 2 to deform without affecting its fixed part. The area of the second flexible electrode 5 is slightly smaller than the area of the pre-stretched dielectric elastomer rectangular film 4. This means that the long and wide edges of the second flexible electrode 5 are both recessed inward by 3-5 mm. In this way, the corresponding areas of the second flexible electrode 5 and the first flexible electrode 3 can cover most of the area of the pre-stretched dielectric elastomer rectangular film 4. The reserved space at the edges serves two main purposes: first, it makes the deformation at the edges more obvious; second, it prevents the edges of the first flexible electrode 3 and the second flexible electrode 5 from directly crossing the pre-stretched dielectric elastomer rectangular film 4 and causing air breakdown after a high-voltage electric field is applied.
[0023] In Example 1, the specific working process of the bistable dielectric elastomer actuator is as follows: the length direction of the unstretched dielectric elastomer rectangular film 2 is regarded as the Y-axis, and the width direction is regarded as the X-axis.
[0024] The initial state of the pre-stretched dielectric elastomer rectangular film 4 is that it is stretched to elastic deformation in both the X-axis and Y-axis directions, with the tensile force in the Y-axis direction being greater than that in the X-axis direction. Based on this, when neither the first flexible electrode 3 nor the second flexible electrode 5 is connected to the circuit, the low-melting-point alloy is solid, which restricts the unstretched dielectric elastomer rectangular film 2 from curling in the Y-axis direction. Therefore, the stretching of the pre-stretched dielectric elastomer rectangular film 4 in the Y-axis is restricted. The entire brake, driven by the drive structure, exhibits deformation in the X-axis, and is in its initial state. Figure 1 As shown.
[0025] By changing the conditions and applying a high voltage to the drive structure, the pre-stretched dielectric elastomer rectangular film 4 will stretch in both the Y and X axes. At this point, the overall deformation of the brake in the X-axis will return to its flat state. However, the low-melting-point alloy, without current flowing through it, remains solid, continuously limiting the unstretched dielectric elastomer rectangular film 2 from curling in the Y-axis direction. Therefore, the pre-stretched dielectric elastomer rectangular film 4 remains unchanged, and the actuator is in its second state. Figure 2 As shown.
[0026] Continuing to change the conditions, the high voltage is disconnected from the drive structure, and a low current is applied to the low-melting-point alloy. The low-melting-point alloy changes from a solid to a liquid state, and the constraint of the low-melting-point alloy on the unstretched dielectric elastomer rectangular film 2 in the Y-axis disappears. At this time, the pre-stretched dielectric elastomer rectangular film 4 returns to its initial state, that is, the tensile force in the Y-axis direction is greater than the tensile force in the X-axis direction. Therefore, the deformation of the pre-stretched dielectric elastomer rectangular film 4 in the initial state is greater in the Y-axis than in the X-axis. So the actuator as a whole can only exhibit deformation in the Y-axis. At this time, the actuator is in the third state, such as... Figure 3 As shown.
[0027] Continuing to change the conditions, a high voltage is applied to the drive structure while a low current is applied to the low-melting-point alloy. The entire drive structure expands along both the Y and X axes. Since the low-melting-point alloy is in a liquid state, the constraint imposed by the low-melting-point alloy on the unstretched dielectric elastomer rectangular film 2 along the Y axis disappears. Therefore, the entire actuator is in a flat state along both the Y and X axes. This is the fourth state. Figure 4 As shown.
[0028] Continuing to change the conditions, the high voltage input to the drive structure is disconnected, and the low current connected to the low-melting-point alloy is also disconnected. The pre-stretched dielectric elastomer rectangular film 4 contracts, but the low-melting-point alloy gradually changes from a liquid to a solid state. The unstretched dielectric elastomer rectangular film 2 is once again constrained by the low-melting-point alloy on the Y-axis. The pre-stretched dielectric elastomer rectangular film 4 returns to its initial state, and the entire drive structure deforms on the X-axis. The actuator returns to its initial state, as shown below. Figure 1 As shown.
[0029] Embodiment 2 of the present invention also provides another type of multistable dielectric elastomer actuator, such as... Figure 5 and Figure 9As shown, the structure includes two non-expandable layers 1 and a square driving structure. The driving structure includes two corresponding square flexible electrodes 9 and a pre-stretched dielectric elastomer square film 10 that has been stretched proportionally in both the length and width directions. The two corresponding square flexible electrodes 9 are respectively attached to the middle of the two sides of the pre-stretched dielectric elastomer square film 10. The area of the square flexible electrode 9 is smaller than the side area of the pre-stretched dielectric elastomer square film 10. The parts of the two sides of the pre-stretched dielectric elastomer square film 10 that are not covered by the square flexible electrodes 9 are respectively attached with square annular non-expandable layers 1. The non-expandable layer 1 located on the front side of the pre-stretched dielectric elastomer square film 10 has notches 8 in the middle of the four sides, and a shape memory alloy layer or a shape memory polymer layer is disposed in the notches 8. A high voltage differential is applied to the square flexible electrodes 9 on both sides of the pre-stretched dielectric elastomer square film 10, driving the pre-stretched dielectric elastomer square film 10 to deform. The pre-stretched dielectric elastomer square film 10 is stretched proportionally, ensuring that the stress in the length and width directions of the square is equal. Shape memory alloy layers or shape memory polymer layers are placed at the four notches 8. When a low current is passed through the shape memory alloy layer or shape memory polymer layer, it can deform. It can deform along with the pre-stretched dielectric elastomer square film 10, or its deformation at the corresponding position can be limited. The principle is the same as that of the previous bistable dielectric elastomer actuator. The overall shape change of the actuator is controlled by controlling the modulus change of the shape memory alloy layer or shape memory polymer layer at the four positions.
[0030] Based on the above embodiments, in a preferred embodiment, notches 8 are respectively provided in the middle of the four sides of the non-expandable layer 1 located behind the pre-stretched dielectric elastomer square film 10, such as... Figure 6 and Figure 10 As shown, a shape memory alloy layer or a shape memory polymer layer is disposed in the notch 8. Similarly, since this structure uses proportional stretching, the same function can be achieved on both sides. When four notches 8 are provided in the non-expandable layer 1 on the rear side, by controlling the modulus change of the shape memory alloy layer or shape memory polymer layer at each of the eight positions, the actuator as a whole can achieve more shape changes. Specifically, the shape memory alloy layer is made of SMA, and the shape memory polymer layer is made of SMP.
[0031] Based on Embodiments 1 and 2 above, in a preferred embodiment, the non-expandable layer 1 is a thin film tape. The non-expandable layer 1 is a thin film that theoretically will not deform, and it has a limiting effect on the driving force of the driving structure.
[0032] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.
Claims
1. A bistable dielectric elastomer actuator, characterized in that, The structure includes a driving structure and a constraint structure. The constraint structure includes an unstretched rectangular dielectric elastomer film (2) and a non-expandable layer (1). The front side of the unstretched rectangular dielectric elastomer film (2) has a long U-shaped groove (6). The length direction of the U-shaped groove (6) is consistent with the length direction of the unstretched rectangular dielectric elastomer film (2), and the U-shaped groove (6) is located in the middle of the width direction of the unstretched rectangular dielectric elastomer film (2). The U-shaped groove (6) is filled with a low melting point alloy. The non-expandable layer (1) is attached to the back side of the unstretched rectangular dielectric elastomer film (2). The driving structure includes a pre-stretched rectangular dielectric elastomer film (4), two first flexible electrodes (3) and one second flexible electrode (5). (4) is an initial state in which the dielectric elastomer is stretched to elastic deformation in both the length and width directions, and the stretching force in the length direction is greater than the stretching force in the width direction. Two first flexible electrodes (3) are located on the unstretched dielectric elastomer rectangular films (2) on both sides of the U-shaped groove (6), and the two first flexible electrodes (3) are connected to the low melting point alloy in the U-shaped groove (6) through wires. The pre-stretched dielectric elastomer rectangular film (4) is pasted to the front of the unstretched dielectric elastomer rectangular film (2) and the two first flexible electrodes (3) are sandwiched between them. The second flexible electrode (5) is pasted to the outer surface of the pre-stretched dielectric elastomer rectangular film (4) and the second flexible electrode (5) corresponds to the two first flexible electrodes (3).
2. The bistable dielectric elastomer actuator according to claim 1, characterized in that, The two long sides of the unstretched dielectric elastomer rectangular film (2) are symmetrically cut with slits (7) perpendicular to the length direction. The two slits (7) are located at the bottom of the unstretched dielectric elastomer rectangular film (2). The size of the prestretched dielectric elastomer rectangular film (4) is equal to the size of the plate above the slits (7) of the unstretched dielectric elastomer rectangular film (2). The second flexible electrode (5) is located inside the plate of the prestretched dielectric elastomer rectangular film (4). The area of the second flexible electrode (5) is slightly smaller than the area of the prestretched dielectric elastomer rectangular film (4).
3. The bistable dielectric elastomer actuator according to claim 1, characterized in that, The non-expandable layer (1) is a thin film tape.
4. A multistable dielectric elastomer actuator, characterized in that, The device includes two non-expandable layers (1) and a square driving structure. The driving structure includes two corresponding square flexible electrodes (9) and a pre-stretched dielectric elastomer square film (10) that has been stretched proportionally in both length and width directions. The two corresponding square flexible electrodes (9) are respectively attached to the middle of the two sides of the pre-stretched dielectric elastomer square film (10). The area of the square flexible electrode (9) is smaller than the side area of the pre-stretched dielectric elastomer square film (10). The parts of the two sides of the pre-stretched dielectric elastomer square film (10) that are not covered by the square flexible electrodes (9) are respectively attached with square annular non-expandable layers (1). The non-expandable layer (1) located on the front side of the pre-stretched dielectric elastomer square film (10) has a notch (8) in the middle of the four sides. A shape memory alloy layer or a shape memory polymer layer is provided in the notch (8).
5. The multistable dielectric elastomer actuator according to claim 4, characterized in that, The non-expandable layer (1) located behind the pre-stretched dielectric elastomer square film (10) has a notch (8) in the middle of each of its four sides, and a shape memory alloy layer or a shape memory polymer layer is provided in the notch (8).