Magnetic drive bistable actuator and manufacturing method thereof

Abstract

The invention provides a magnetically-driven bistable actuator and a manufacturing method thereof, and relates to the field of flexible drivers, and the actuator comprises a magnetic frame and a pre-stretched film; the magnetic frame is in a buckling shape and is fixed to the pre-stretching film, when external magnetic field excitation is applied to the magnetic frame, the magnetic frame generates torque and magnetic force, and the buckling direction changes. The pre-stretched film enables the whole to form a bistable structure, and the bistable structure provides the rapid deformation capability of the actuator. The actuator is driven by a magnetic field, is flexible and high in adaptability, can achieve cable-free driving, and has the advantages of being high in output, rapid in driving, low in cost, simple in manufacturing process and the like.

Description

Technical Field

[0001] The present invention belongs to the field of flexible actuators, and particularly relates to a magnetically driven bistable actuator and a manufacturing method thereof. Background Art

[0002] Magnetically driven bistable actuators represent an important innovation in the development of responsive and energy-efficient systems, with potential applications in various fields such as soft robotics, biomedical devices, and adaptive structures. Bistable actuators are characterized by their ability to maintain two stable positions without continuous power supply, enabling efficient energy utilization and rapid switching between these states when triggered by an external force. For example, the "reconfigurable bistable device" disclosed in Chinese Invention Patent Publication CN 103035427 A, which uses a shape memory alloy to fix both ends, has the disadvantages of slow speed response and the need for fixation.

[0003] The combination of magnetic drive and bistable mechanisms offers unique advantages such as precise control, rapid response, and remote wireless control. Magnetic drive specifically utilizes the force generated by a magnetic field to cause the movement or deformation of the actuator. This mechanism has many advantages as it enables remote control, rapid actuation, and the possibility of miniaturization, making it suitable for applications in narrow or inaccessible environments. Integrating a bistable mechanism into a magnetic drive system adds another level of versatility, enabling the actuator to efficiently switch between stable configurations, thus expanding its potential application scenarios. For example, in soft robotics, bistable actuators can facilitate complex multi-mode movements such as crawling, flipping, or climbing, enabling highly adaptable navigation across various terrains. However, existing magnetic field-driven bistable actuators still require fixation and cannot achieve cable-free operation. Summary of the Invention

[0004] In order to at least address one of the deficiencies existing in the prior art, the present invention provides a magnetically driven bistable actuator that combines a pre-stretched film and a magnetic frame, is driven by a magnetic field, and is a flexible and adaptable actuator capable of achieving cable-free drive.

[0005] To achieve the object of the present invention, a magnetically driven bistable actuator provided by the present invention includes a magnetic frame and a pre-stretched film;

[0006] The magnetic frame is in a buckled shape and fixed on the pre-stretched film. When an external magnetic field excitation is applied to the magnetic frame, the magnetic frame generates torque and magnetic force, and the buckling direction changes.

[0007] The pre-stretched film is fixed on the magnetic frame, and the pre-stretched film is in a stretched state. Due to the pre-stretching of the film, the magnetic frame is in a buckled shape, and a bistable configuration can be formed, enabling the actuator to maintain two stable states.

[0008] Further, the magnetic frame includes a first fixing member, a second fixing member, and a buckling member. The first fixing member and the second fixing member are disposed opposite to each other. The buckling member is located between the first fixing member and the second fixing member. The first fixing member and the second fixing member are connected by a pre-stretched film.

[0009] Further, the buckling member is U-shaped. When the buckling direction changes, the buckling member becomes an inverted U-shape. The actuator can switch between two stable states: U-shape and inverted U-shape.

[0010] Further, the magnetic frame is an elastic soft body, and magnetic particles are provided on the elastic soft body. Preferably, the magnetic particles can be made of rare earth permanent magnet particles such as neodymium iron boron particles.

[0011] Further, the outer shape of the magnetic frame is in the shape of "I".

[0012] Further, the magnetization direction of the magnetic frame is along the thickness direction of the magnetic frame.

[0013] Further, the elastic soft body is any one of polydimethylsiloxane, natural rubber, and silica gel.

[0014] Further, the material of the pre-stretched film is any one of stretchable silica gel and hydrogel.

[0015] Further, an external magnetic field excitation is applied by a magnetic field generator. More preferably, the magnetic field generator can be an electromagnet or a permanent magnet.

[0016] Further, there are multiple magnetic drive bistable actuators, and the multiple magnetic drive bistable actuators are connected in series or in parallel.

[0017] Further preferably, two-stage drivers are connected in series, and one of the drivers can be individually stimulated by a small permanent magnet.

[0018] Further, the actuator is used to switch the power supply.

[0019] The present invention also provides a manufacturing method of a magnetic drive bistable actuator, including the following steps:

[0020] Hard magnetic particles are provided on an elastic soft body to obtain a magnetic frame;

[0021] The pre-stretched film is stretched to a set length;

[0022] The magnetic frame is fixed to the pre-stretched film.

[0023] Magnetic Frame Structure: The magnetic frame is a key component of the system. The magnetic frame enables it to generate torque and magnetic force under the action of an external magnetic field, realizing the transformation of form (the principle of magnetic drive). The pre-stretched film is integrated into the magnetic frame to provide additional elasticity and energy storage capacity. During the process of form transformation, the pre-stretched film can store and release energy (both the pre-stretched film and the buckled magnetic field frame store energy), thereby improving the efficiency and responsiveness of the system. The pre-stretched design of the film enables it to provide additional restoring force when the state of the actuator changes, enhancing the overall performance of the system (due to the energy in the stretched film). Therefore, this actuator can be applied to a variety of fields. For example, in soft robots, the bistable actuator can facilitate complex multi-mode motions such as jumping, crawling, flipping, or climbing, enabling it to highly adapt to navigation on various terrains.

[0024] Compared with the prior art, the beneficial effects that the present invention can achieve include:

[0025] (1) Traditional bistable mechanisms often rely on fixed structures or cables to maintain stability or transmit power, which limits the flexibility of the system. In the present invention, through magnetic drive combined with a bistable structure, the actuator can self-maintain a stable state without external fixing devices, avoiding the dependence on physical fixation or cables in the traditional solution.

[0026] Specifically, the bistable magnetic frame can switch between two different stable states. When an external excitation causes it to switch, the magnetic field provides the necessary driving force to quickly reach the deformation threshold force instead of slowly loading to the deformation threshold force, which can avoid uncertainties during the loading process. It can not only get rid of the bondage of traditional cables, but also due to the magnetic force and bistable characteristics, the actuator can continuously work without complex physical connections, reducing the complexity of installation and maintenance.

[0027] (2) The magnetically driven bistable actuator utilizes the instantaneous acting force of the magnetic field and can quickly achieve driving and response by precisely controlling the change of the magnetic field. The combination of the bistable structure enables the actuator to quickly switch between two stable states without traditional driving methods, such as the form of fixing both ends in the form of a shape memory alloy.

[0028] Specifically, magnetic drive can perform rapid adjustment without mechanical contact, reducing energy loss and mechanical response time. The bistable structure itself has high switching efficiency and can achieve state conversion in a short time, thereby improving the dynamic response performance of the system. Essentially, magnetic drive and the bistable structure complement each other to achieve faster and more stable driving. Description of the Drawings

[0029] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings, where:

[0030] Figure 1 is a schematic structural diagram of a magnetic-driven bistable actuator provided by an embodiment of the present invention.

[0031] Figure 2 is a schematic diagram of the internal magnetic field distribution of the magnetic-driven bistable actuator in an embodiment of the present invention.

[0032] Figure 3 is a schematic manufacturing diagram of the magnetic-driven bistable actuator in an embodiment of the present invention.

[0033] Figure 4 is a schematic working diagram of the magnetic-driven bistable actuator in an embodiment of the present invention.

[0034] Figure 5 is a schematic structural diagram of the series connection of two-stage drivers in an embodiment of the present invention.

[0035] In the figure, 1 is a magnetic frame, and 2 is a pre-stretched film. Detailed implementation manners

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts are within the scope of protection of the present invention.

[0037] In addition, in the present invention, descriptions such as "first" and "second" are only for descriptive purposes, and do not particularly refer to the order or sequence. Nor are they used to limit the present invention. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features.

[0038] Please refer to Figure 1, A magnetic-driven bistable actuator provided by the present invention includes a magnetic frame 1 and a pre-stretched film 2. The magnetic frame 1 is in a buckled shape and is fixed on the pre-stretched film 2. When an external magnetic field excitation is applied to the magnetic frame 1, the magnetic frame 1 generates torque and magnetic force, and the buckling direction changes.

[0039] The magnetic frame 1 enables the entire actuator to achieve different morphological transformations under the control of an external magnetic field, thereby having diverse motion capabilities in a complex environment. The pre-stretched film 2 provides additional elasticity, enabling the actuator to store and release energy during morphological changes, further improving the driving efficiency.

[0040] In some embodiments of the present invention, the magnetic frame 1 includes a first fixing member, a second fixing member, and a buckling member. The first fixing member and the second fixing member are arranged opposite to each other. The buckling member is located between the first fixing member and the second fixing member. There are two pieces of the pre-stretched film 2, and the first fixing member and the second fixing member are connected by the pre-stretched film 2.

[0041] In some embodiments of the present invention, the buckling member is in a U shape, and when the buckling direction changes, the buckling member is in an inverted U shape.

[0042] The magnetic-driven bistable actuator has bistable characteristics and has two stable states. For example, if the buckling member of the magnetic-driven bistable actuator is maintained on the table in a U shape, when a magnetic field stimulus is given, the buckling member can be switched to an inverted U shape and can maintain its shape without external force. The magnetic frame 1 thus forms a buckling structure, and the pre-stretched film 2 remains in a stretched state). The pre-stretched film 2 is used to maintain the buckling structure of the magnetic frame 1.

[0043] The magnetic-driven bistable actuator can generate a magnetic torque under the action of an external magnetic field. The generation of the magnetic torque promotes the sudden change force of the magnetic frame 1 from the first stable state (U shape) to the second stable state (inverted U shape), causing the magnetic frame 1 to deform. The control is simple and convenient to operate, as Figure 4 shown. During operation, assume that the current magnetic-driven bistable actuator is in a U shape, and the magnetic distribution is as shown in the right figure of Figure 4 . First, an upward external magnetic field is instantaneously applied. Under the action of the magnetic torque, the magnetic-driven bistable actuator will instantaneously change to an inverted U shape. During this period, the buckling member of the magnetic frame 1 will instantaneously contact the ground and bounce, and will always maintain an inverted U shape without the action of the magnetic field. Therefore, this actuator can be applied to multiple fields. For example, in soft robots, the bistable actuator can promote complex multi-mode motions such as jumping, crawling, flipping, or climbing, enabling the robot to efficiently adapt to and navigate various complex terrains.

[0044] The magnetic frame 1 is an elastic soft body, and hard magnetic particles are provided on the elastic soft body. In some embodiments of the present invention, the elastic soft body is any one of polydimethylsiloxane, natural rubber, and silica gel.

[0045] In some embodiments of the present invention, the magnetic frame 1 is in an I shape. The buckling member is rectangular. In other embodiments, the buckling member can also be of other shapes. The structure of the magnetic frame has high adaptability and can be set into different shapes and sizes according to application requirements to adapt to different needs.

[0046] In some embodiments of the present invention, the material of the pre-stretched film 2 is any one of silica gel and hydrogel.

[0047] An external magnetic field excitation can be applied through a magnetic field generator. In some embodiments of the present invention, an external magnetic field excitation is applied through a permanent magnet.

[0048] There can be multiple magnetic drive bistable actuators, and multiple magnetic drive bistable actuators are connected in series or in parallel. In some embodiments of the present invention, multiple magnetic drive bistable actuators are connected in series to achieve simultaneous operation of multiple stages in series and form a multi-stable configuration. Further, each stage of the actuator only needs to be stimulated once by a permanent magnet to deform and does not require continuous magnetic field stimulation. The meaning of simultaneous operation is not that each needs to deform, but rather to maintain a specific shape according to the actual situation. For example, there are three actuators, the first actuator and the third actuator are U-shaped, and the second actuator is an inverted U-shaped, similar to a W shape. They can be stimulated in sequence as needed by a permanent magnet, and the number of actuators can be equal to or unequal to the number of permanent magnets.

[0049] In some embodiments of the present invention, a manufacturing method of a magnetic field-driven bistable structure is provided. Please refer to Figure 3 , including the following steps:

[0050] Step 1: Manufacture the magnetic frame 1 and magnetize it along the thickness direction of the magnetic frame 1.

[0051] Among them, the matrix of the magnetic frame 1 can adopt elastic soft bodies with low stretchability such as polydimethylsiloxane (pdms), natural rubber, and silica gel, and the magnetic particles adopt hard magnetic particles. Preferably, liquid PDMS and magnetic particles are mixed and then solidified into shape, and the magnetic field particles are uniformly embedded inside the PDMS. The hard magnetic particles have a relatively high maximum magnetic energy product, which means that they can store and release a larger magnetic energy per unit volume. In addition, the hard magnetic particles also have a relatively high coercivity, a relatively high residual magnetic flux density, and a relatively large residual magnetization intensity, further improving their performance and stability. As a preference, the hard magnetic particles are set as neodymium iron boron magnetic powder.

[0052] Step 2: Use a laser cutting machine to cut the magnetic frame into a "worker" shape to obtain the magnetic frame 1.

[0053] Step 3: Stretch the stretchable film to a set length.

[0054] The stretchable film is made of materials with high stretchability such as silicone (commercial, Ecoflex, etc.), hydrogel, etc. Ecoflex series silicone materials are preferred because they can be highly stretched.

[0055] Step 4: Paste and fix the magnetic frame 1 onto the stretchable film.

[0056] Step 5: Use a laser cutting machine to cut the stretchable film to obtain an actuator including the magnetic frame 1 and the pre-stretched film 2.

[0057] This manufacturing method can transform a two-dimensional structure into a three-dimensional structure.

[0058] In some embodiments of the present invention, the magnetic drive bistable actuator is used for switching the power supply. Specifically, the actuator can be controlled by a magnetic field to enter a narrow space to switch the power supply, and the shape of the buckling member can be controlled by a magnetic field. For example, when the U-shaped is energized and the inverted U-shaped is de-energized, the power supply is switched by changing the buckling direction of the buckling member.

[0059] The bistable actuator provided in the foregoing embodiments of the present invention can achieve precise coupling of the magnetic field and the bistable mechanical mechanism, thereby realizing enhanced drive control and utilization of energy efficiency. The actuator of the present invention does not need to be fixed and can be driven by a magnetic field to achieve cable-free control, can achieve precise movement and high responsiveness, and can solve problems such as slow response speed of existing flexible drivers. And the bistable driver can be expanded into multiple ones to obtain a multi-stable robot.

[0060] The present invention not only improves the functional capabilities of the actuator but also expands its applications in advanced robotic systems and intelligent devices.

[0061] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A magnetically driven bistable actuator, characterized in that: It comprises a magnetic frame (1) and a pre-stretched film (2); The magnetic frame (1) is in a bent shape and is fixed on a pre-stretched film (2). When an external magnetic field excitation is applied to the magnetic frame (1), the magnetic frame (1) generates torque and magnetic force, and the bending direction changes.

2. A magnetically driven bistable actuator according to claim 1, characterized in that: The magnetic frame (1) comprises a first fixing member, a second fixing member and a bending member, the first fixing member and the second fixing member are arranged opposite to each other, the bending member is located between the first fixing member and the second fixing member, and the first fixing member and the second fixing member are connected via a pre-stretched film (2).

3. A magnetically driven bistable actuator according to claim 2, characterized in that: The buckling piece is U-shaped, and when the buckling direction changes, the buckling piece is inverted U-shaped.

4. The magnetically driven bistable actuator according to claim 1, characterized in that: The magnetic frame (1) is an elastic soft body, and magnetic particles are arranged on the elastic soft body.

5. A magnetically driven bistable actuator according to claim 4, characterized in that: The elastic soft body is any one of polydimethylsiloxane, natural rubber and silicone.

6. The magnetically driven bistable actuator according to claim 1, characterized in that: The material of the pre-stretched film (2) is any one of silica gel and hydrogel.

7. The magnetically driven bistable actuator according to claim 1, characterized in that: The external magnetic field excitation is applied by a magnetic field generator.

8. The magnetically driven bistable actuator according to claim 1, characterized in that: There are multiple magnetically driven bistable actuators, and the multiple magnetically driven bistable actuators are connected in series or in parallel.

9. A magnetically driven bistable actuator according to any one of claims 1 to 8, characterized in that: The actuator is used to switch power.

10. A method for manufacturing a magnetically driven bistable actuator according to any one of claims 1 to 9, characterized in that: The following steps are involved: Arranging hard magnetic particles on an elastic soft body to obtain a magnetic frame (1); stretching the pre-stretched film (2) to a set length; The magnetic frame (1) is fixed to the pre-stretched film (2).

Images