Active variable-stiffness micro-displacement actuator based on magnetostrictive driving and method

Abstract

According to the active variable-stiffness micro-displacement actuator based on magnetostrictive driving and the method, magnetostrictive materials are used as actuating elements, and dynamic adjustment of structural stiffness is achieved based on the delta E effect of the magnetostrictive materials. Comprising a magnetostrictive driving unit, a permanent magnet, an exciting coil, a framework and a rhombic pre-pressing mechanism. Wherein the permanent magnets at the two ends of the magnetostriction driving unit provide a bias magnetic field, and the excitation coil provides an alternating magnetic field. The strength and frequency of the alternating magnetic field are controlled by changing the current in the coil, the material elasticity modulus of the magnetostriction driving unit is adjusted, and dynamic adjustment of the structural rigidity of the actuator is achieved. The diamond-shaped pre-pressing mechanism provides pre-pressing force for the magnetostrictive material, and meanwhile magnetic flux loops of the magnetostrictive driving unit and the permanent magnet can be closed. The active variable-stiffness elastic micro-displacement actuator has the advantages of being compact in structure, small in size, high in frequency response block, low in driving voltage, easy to install and the like. The method is suitable for the fields of aerospace, ultra-precision driving, structural vibration control and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-vibration isolation in precision machinery environments, and in particular to an active variable-stiffness elastic micro-displacement actuator based on magnetostrictive drive and a control method thereof. Background Art

[0002] With the rapid development of precision machining and measurement technologies, micro-vibration has become a key factor affecting the accuracy of precision machining and precision instrument measurement. In real-world engineering environments, external disturbances such as equipment startup and shutdown, operation, and personnel activities inevitably transmit vibration interference through the ground. Although the displacement amplitude of this vibration is typically in the micrometer range, its frequency components range from low to medium-high frequencies. At the very least, this can reduce the machining accuracy and measurement sensitivity of precision machinery and instruments. At worst, it can cause equipment malfunctions and lead to major production accidents.

[0003] Magnetostrictive materials are intelligent materials that exhibit bidirectional magnetic-mechanical coupling. Compared to piezoelectric materials, shape memory alloys, and electrostrictive materials, they offer advantages such as high energy conversion efficiency, large magnetostrictive strain, high Curie temperature, short dynamic response time, excellent frequency response characteristics, and high energy density. These characteristics give magnetostrictive materials potential advantages in vibration control and sensor applications. Actuators made from magnetostrictive materials offer advantages such as low drive voltage, low noise, and high driving force. However, they are also bulky, generate high heat, and have low output displacement, which reduces their efficiency and makes them unsuitable for industrial applications. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide an active variable-stiffness micro-displacement actuator and control method based on magnetostrictive drive, which uses electric drive control to achieve in-situ stiffness adjustment or stiffness switching of the structure. By improving the dynamic response capability and bandwidth of the magnetostrictive material, it can better adapt to complex vibration environments.

[0005] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] An active variable-stiffness micro-displacement actuator based on magnetostrictive drive comprises a diamond-shaped preload mechanism 1, an upper permanent magnet 2, a magnetostrictive drive unit 3, a lower permanent magnet 4, a coil bobbin 5, and an excitation coil 6. The upper and lower ends of the magnetostrictive drive unit 3 are rigidly connected to the upper and lower permanent magnets 2 and 4, respectively, and are mounted inside the diamond-shaped preload mechanism 1. The end surfaces of the upper and lower permanent magnets 2 and 4, respectively, that contact the magnetostrictive drive unit 3, are grooved, allowing the magnetostrictive drive unit 3 to be embedded in the upper and lower permanent magnets 2 and 4. The diamond-shaped preload mechanism 1 forms an interference fit with the magnetostrictive drive unit 3, the upper and lower permanent magnets 2, and the lower permanent magnets 4, providing preload to the magnetostrictive drive unit 3. The coil bobbin 5 is mounted outside the magnetostrictive drive unit 3 and is wound around the excitation coil 6.

[0007] Preferably, arched beams are symmetrically arranged on the upper and lower sides of the diamond preloading mechanism 1, and the inner cavity length of the diamond preloading mechanism 1 is smaller than the length of the magnetostrictive drive unit 3, so that the diamond preloading mechanism 1 has an interference fit with the magnetostrictive drive unit 3, the upper permanent magnet 2 and the lower permanent magnet 4.

[0008] Preferably, a mounting hole is provided at the bottom of the diamond-shaped pre-pressing mechanism 1 for easy installation.

[0009] Preferably, the diamond-shaped pre-stressing mechanism 1 uses a magnetic conductive material with a high elastic modulus to provide high structural rigidity and realize the closure of the magnetic circuit of the magnetostrictive drive unit.

[0010] Preferably, the magnetic conductive material with a high elastic modulus is spring steel, silicon steel or alloy structural steel.

[0011] Preferably, the upper permanent magnet 2 and the lower permanent magnet 4 are made of neodymium iron boron material and are magnetized in the vertical direction, with the top being the N pole and the bottom being the S pole; the magnetization direction must remain consistent during the installation process.

[0012] In a control method for an active variable-stiffness micro-displacement actuator based on magnetostrictive drive, a diamond-shaped preload mechanism 1 provides preload to the magnetostrictive drive unit 3 through an interference fit, placing the magnetostrictive drive unit 3 in a compressed state. The magnetic flux generated by the upper permanent magnet 2 and the lower permanent magnet 4 at both ends of the magnetostrictive drive unit 3 passes through the diamond-shaped preload mechanism 1, forming a closed magnetic circuit and providing a bias magnetic field to the magnetostrictive drive unit 3, placing the magnetostrictive drive unit 3 in a magnetic bias state. Current is passed through the excitation coil 6, generating an axial magnetic field. Adjusting the amplitude and frequency of the current causes the generated axial magnetic field to vary with the current. This magnetic field variation, combined with the bias magnetic field generated by the upper permanent magnet 2 and the lower permanent magnet 4, changes the internal magnetic field state of the magnetostrictive drive unit 3. The elastic modulus of the material of the magnetostrictive drive unit 3 varies under different magnetic field states. Rapid switching of the material elastic modulus is achieved by electrically controlling the magnetic field, thereby achieving dynamic adjustment of the actuator structural stiffness.

[0013] Compared with existing technologies, this invention offers the following advantages: It utilizes electric drive control to achieve in-situ stiffness adjustment or switching of the structure. By improving the dynamic response and bandwidth of the magnetostrictive material, it can better adapt to complex vibration environments. The present invention integrates the magnetic flux circuit structure with the preload mechanism, making the actuator structure more compact, effectively reducing the actuator's size and improving the device's space utilization. It eliminates the need for additional heat dissipation devices such as water or oil cooling, reducing the actuator's structural complexity and facilitating fabrication, installation, and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the overall structure of the actuator of the present invention.

[0015] Figure 2 It is a cross-sectional view of the structure of the present invention.

[0016] Figure 3 This is a schematic diagram of the magnetostrictive drive unit and permanent magnet structure of the present invention.

[0017] Figure 4 Schematic diagram of the magnetic flux circuit structure of the actuator of the present invention.

[0018] Figure 5 This is a schematic diagram of the excitation coil and skeleton structure of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described in detail below with reference to the accompanying drawings and specific implementations.

[0020] like Figure 1 and Figure 2 As shown, the present invention discloses an active variable-stiffness micro-displacement actuator based on magnetostrictive drive, comprising a diamond-shaped preload mechanism 1, an upper permanent magnet 2, a magnetostrictive drive unit 3, a lower permanent magnet 4, a coil bobbin 5, and an excitation coil 6. The magnetostrictive drive unit 3 is rigidly connected to the upper and lower permanent magnets 2 and 4 at its upper and lower ends, respectively, and is mounted inside the diamond-shaped preload mechanism 1. The end surfaces of the upper and lower permanent magnets 2 and 4 that contact the magnetostrictive drive unit 3 each have grooves, allowing the magnetostrictive drive unit 3 to fit within the upper and lower permanent magnets 2 and 4. The diamond-shaped preload mechanism 1 forms an interference fit with the magnetostrictive drive unit 3, the upper and lower permanent magnets 2, and 4, providing preload to the magnetostrictive drive unit 3. The coil bobbin 5 is mounted outside the magnetostrictive drive unit 3 and is wound around the excitation coil 6.

[0021] like Figure 2As shown, the present invention presents an active variable-stiffness micro-displacement actuator based on magnetostrictive drive. Arched beams are symmetrically arranged on the upper and lower sides of the diamond-shaped preload mechanism 1. The inner cavity length of the diamond-shaped preload mechanism 1 is shorter than the magnetostrictive drive unit 3, resulting in an interference fit between the diamond-shaped preload mechanism 1, the magnetostrictive drive unit 3, the upper permanent magnet 2, and the lower permanent magnet 4. A mounting hole is provided at the bottom of the diamond-shaped preload mechanism 1 for easy installation.

[0022] As a preferred embodiment of the present invention, the diamond preloading mechanism 1 uses a magnetic material with a high elastic modulus, such as spring steel, silicon steel or alloy structural steel, which can withstand large stress without plastic deformation and has good magnetic conductivity.

[0023] like Figure 3 As shown in the figure, as a preferred embodiment of the present invention, the upper permanent magnet 2 and the lower permanent magnet 4 are made of neodymium iron boron material and are magnetized axially, with the bottom pole being the north pole and the top pole being the south pole. During installation, the magnetization direction must be kept consistent to keep the magnetostrictive drive unit 3 in a prepolarized state, avoiding frequency doubling and ensuring operation in the linear region.

[0024] like Figure 4 As shown, the working principle of the present invention is as follows: the diamond-shaped preload mechanism 1 applies preload to the magnetostrictive drive unit 3 through an interference fit, placing the magnetostrictive drive unit 3 in a compressed state. The magnetic flux generated by the permanent magnets at both ends of the magnetostrictive drive unit 3 passes through the diamond-shaped preload mechanism 1, forming a closed magnetic circuit and providing a bias magnetic field to the magnetostrictive drive unit 3, placing the magnetostrictive drive unit 3 in a magnetic bias state. Current is passed through the excitation coil 6, generating an axial magnetic field. Adjusting the amplitude and frequency of the current also causes the generated axial magnetic field to vary with the current. This magnetic field variation, combined with the bias magnetic field generated by the permanent magnets, alters the internal magnetic field state of the magnetostrictive drive unit 3. The elastic modulus of the material of the magnetostrictive drive unit 3 varies under different magnetic field conditions. By electrically controlling the magnetic field, this material elastic modulus is rapidly switched, enabling dynamic adjustment of the actuator structural stiffness, thereby achieving vibration suppression.

[0025] In the present invention, the permanent magnets at both ends of the magnetostrictive drive unit provide a bias magnetic field, and the excitation coil provides an alternating magnetic field. By varying the current in the coil to control the intensity and frequency of the alternating magnetic field, the material elastic modulus of the magnetostrictive drive unit is adjusted, enabling dynamic regulation of the actuator's structural stiffness. The diamond-shaped preload mechanism provides preload to the magnetostrictive material while closing the magnetic flux loop between the magnetostrictive drive unit and the permanent magnet. The active variable stiffness elastic micro-displacement actuator of the present invention has the advantages of a compact structure, small size, low frequency response, low drive voltage, and ease of installation. It is suitable for applications in aerospace, ultra-precision drive, and structural vibration control.

Claims

1. An active variable stiffness micro-displacement actuator based on magnetostrictive drive, characterized by: The invention comprises a rhombus pre-pressing mechanism (1), an upper permanent magnet (2), a magnetostrictive drive unit (3), a lower permanent magnet (4), a coil frame (5) and an excitation coil (6); the upper end and the lower end of the magnetostrictive drive unit (3) are rigidly connected to the upper permanent magnet (2) and the lower permanent magnet (4) respectively, and are installed on the inner side of the rhombus pre-pressing mechanism (1); the end surfaces of the upper permanent magnet (2) and the lower permanent magnet (4) respectively contacting the magnetostrictive drive unit (3) are provided with grooves, so that the magnetostrictive drive unit (3) can be embedded in the upper permanent magnet (2) and the lower permanent magnet (4); the rhombus pre-pressing mechanism (1) is interference-fitted with the magnetostrictive drive unit (3), the upper permanent magnet (2) and the lower permanent magnet (4), and provides pre-pressing force to the magnetostrictive drive unit (3); the coil frame (5) is installed on the outer side of the magnetostrictive drive unit (3) and is wound around the excitation coil (6).

2. The active variable stiffness micro-displacement actuator based on magnetostrictive drive according to claim 1, characterized in that: Arched beams are symmetrically arranged on the upper and lower sides of the diamond-shaped pre-stressing mechanism (1), and the inner cavity length of the diamond-shaped pre-stressing mechanism (1) is shorter than the length of the magnetostrictive drive unit (3), so that the diamond-shaped pre-stressing mechanism (1) is interference-fitted with the magnetostrictive drive unit (3), the upper permanent magnet (2), and the lower permanent magnet (4).

3. The active variable stiffness micro-displacement actuator based on magnetostrictive drive according to claim 1, characterized in that: The bottom of the diamond-shaped pre-pressing mechanism (1) is provided with a mounting hole.

4. The active variable stiffness micro-displacement actuator based on magnetostrictive drive according to claim 1, characterized in that: The diamond-shaped pre-stressing mechanism (1) adopts a magnetic conductive material with a high elastic modulus, provides high structural rigidity, and realizes the closure of the magnetic circuit of the magnetostrictive drive unit.

5. The active variable stiffness micro-displacement actuator based on magnetostrictive drive according to claim 4, characterized in that: The magnetic conductive material with high elastic modulus is made of spring steel, silicon steel or alloy structural steel.

6. The active variable stiffness micro-displacement actuator based on magnetostrictive drive according to claim 1, characterized in that: The upper permanent magnet (2) and the lower permanent magnet (4) are made of neodymium iron boron material and are magnetized in a vertical direction, with the top being the N pole and the bottom being the S pole; the magnetization direction must remain consistent during the installation process.

7. The control method of the active variable stiffness micro-displacement actuator based on magnetostrictive drive according to any one of claims 1 to 6, characterized in that: The rhombus pre-stressing mechanism (1) provides pre-stressing force to the magnetostrictive drive unit (3) through interference fit, so that the magnetostrictive drive unit (3) is in a compressed state; the magnetic flux generated by the upper permanent magnet (2) and the lower permanent magnet (4) at both ends of the magnetostrictive drive unit (3) passes through the rhombus pre-stressing mechanism (1), forming a closed magnetic circuit, and providing a bias magnetic field to the magnetostrictive drive unit (3), so that the magnetostrictive drive unit (3) is in a magnetic bias state; current is passed through the excitation coil (6), and the excitation coil (6) generates an axial magnetic field. The amplitude and frequency of the current are adjusted, and the generated axial magnetic field also changes with the current; the magnetic field change is superimposed on the bias magnetic field generated by the upper permanent magnet (2) and the lower permanent magnet (4), which changes the internal magnetic field state of the magnetostrictive drive unit (3); the elastic modulus of the material of the magnetostrictive drive unit (3) is different under different magnetic field states, and the rapid switching of the elastic modulus of the material is completed by electrically controlling the magnetic field, thereby realizing dynamic adjustment of the structural stiffness of the actuator.

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