M-shaped low-frequency vibration isolation structure simulating arthropod leg structure

Abstract

The invention discloses an M-shaped low-frequency vibration isolation structure simulating an arthropod leg structure, and belongs to the technical field of vibration isolation. A design method of a bionic M-shaped structure is provided, the bionic M-shaped structure is constructed by using components such as a connecting rod, a bearing, a spring and a guide device thereof, the connecting rod simulates the geometrical shape and structure of the leg of an arthropod, and the spring and the component thereof approximately simulate the leg muscle structure. The structural rigidity design method of the bionic M-shaped structure is provided, the method comprises nonlinear positive rigidity design and nonlinear negative rigidity design, the special nonlinear positive rigidity characteristic of the bionic M-shaped structure is utilized, negative rigidity can be better adapted, and therefore the quasi-zero rigidity range is remarkably widened. Furthermore, the relationship between the effective vibration isolation load and the structural parameters of the bionic M-shaped structure is given. Finally, the quasi-zero stiffness condition of the bionic M-shaped structure is given, and the result shows that the structure can effectively reduce the vibration isolation starting frequency and improve the low-frequency vibration isolation performance.

Description

Technical Field

[0001] The invention relates to the technical field of vibration isolation, and in particular to a bionic M-type low-frequency vibration isolation structure based on an arthropod leg structure. Background Art

[0002] With the increasing frequency of space activities, the requirements for pointing accuracy and stability of spacecraft are constantly increasing. For example, tasks such as space laser communication, space-to-earth remote sensing, and space astronomical observation all require high-precision pointing performance. The normal operation of the transmission device on the spacecraft will produce micro-vibration, which has the characteristics of wide frequency band, small amplitude, and difficult to control. Micro-vibration will have a great impact on the pointing accuracy and stability of the spacecraft. For example, the micro-vibration of remote sensing satellites is caused by moving parts, which stimulates structural vibration and is transmitted to the installation part of the remote sensor, resulting in a decrease in imaging quality. When there is no micro-vibration interference, the focusing accuracy of the camera is 5μm; after being disturbed by micro-vibration, the focusing accuracy exceeds 14.97μm, and the image becomes blurred. The low-frequency vibration isolation technology on the spacecraft is mainly active vibration isolation, which requires energy input and has lower stability than passive vibration isolation. In order to isolate low-frequency micro-vibrations on spacecraft, researchers proposed a quasi-zero stiffness isolator based on the theory of nonlinear dynamics. The principle of quasi-zero stiffness is to combine positive and negative stiffness to make the quasi-zero stiffness structure have the characteristics of "high static and low dynamic", while ensuring the bearing capacity of the structure and having a lower vibration isolation frequency.

[0003] The prior art discloses a three-spring structure, in which one vertical spring provides positive stiffness, and the other two inclined springs provide negative stiffness. Compared with a linear isolator composed of a positive stiffness spring, the three-spring structure can achieve quasi-zero stiffness at the static equilibrium position and obtain a lower starting vibration isolation frequency. However, its quasi-zero stiffness range is very limited, so under strong excitation conditions, the starting frequency of vibration isolation will increase rapidly. In order to widen the quasi-zero stiffness range, researchers have made improvements on the original quasi-zero stiffness structure. Technicians in this field introduced nonlinearity and pre-compression into the inclined springs of the three-spring quasi-zero stiffness system. Theoretical research results show that this method can widen the quasi-zero stiffness range, but the introduction of spring pre-compression and nonlinearity makes it difficult to perform in practice.

[0004] In nature, arthropods such as spiders and mantises live on low-frequency vibrating webs or leaves. Compared with the body of the arthropod, the leaves and webs shake more, so their leg structure has the function of isolating large-amplitude vibrations and maintaining the stability of the trunk. Combining the shape of the arthropod's legs with the design of the quasi-zero stiffness vibration isolation node, an M-type low-frequency vibration isolation structure imitating the leg structure of the arthropod is proposed. Although the positive stiffness spring of the M-type structure itself is not nonlinear, due to the position of the positive stiffness spring of the M-type structure, its equivalent stiffness is nonlinear. After the positive and negative stiffnesses are offset, the structure has a wider quasi-zero stiffness range, which can improve the vibration isolation performance under large excitation, and this improvement method is easier to implement. Summary of the invention

[0005] The present invention designs a quasi-zero stiffness structure with a large quasi-zero stiffness range based on the shape of the leg structure of arthropods such as spiders and mantises. For the classic quasi-zero stiffness vibration isolation structure, when the excitation amplitude is large, the displacement of the isolated object will exceed the quasi-zero stiffness range. This causes the equivalent stiffness of the structure to increase significantly when the excitation is large, and the low-frequency vibration isolation performance of the structure decreases. The reason why the quasi-zero stiffness range of the classic quasi-zero stiffness structure is limited is that the positive stiffness is provided by the vertical spring as a constant value, and the inclined spring can only provide negative stiffness within a limited range near the equilibrium position. Outside this range, the inclined spring provides positive stiffness, so that the equivalent stiffness of the structure is even higher than that of the vertical spring.

[0006] In order to solve the problem that the range of quasi-zero stiffness in classical structures is small and the existing improvement methods are difficult to implement, the present invention proposes a bionic M-type quasi-zero stiffness structure; the negative stiffness of the bionic M-type quasi-zero stiffness structure is provided by an inclined spring, and the positive stiffness is provided by a horizontal spring, and the horizontal spring is arranged in a position so that the M-type structure has nonlinear positive stiffness. When the negative stiffness of the M-type structure increases with the increase of displacement, the positive stiffness decreases with the increase of displacement, which expands the range of positive and negative stiffness offset, so the range of quasi-zero stiffness is widened. At the same time, the problem that needs to be solved for the proposed M-type bionic structure to achieve quasi-zero stiffness is to give the relationship between the structural parameters, that is, the quasi-zero stiffness design criteria.

[0007] The present invention is achieved in that:

[0008] An M-type low-frequency vibration isolation structure imitating the leg structure of an arthropod. The structure of the present invention improves the vibration isolation performance by broadening the range of quasi-zero stiffness by imitating the geometric nonlinearity of the arthropod structure itself. The structure of the present invention is an arthropod-like structure; it includes four interconnected rods, namely one rod, two rods, three rods, and four rods, and the connection points of the one rod, the two rods, the three rods, and the four rods are connected by horizontal springs, and the two ends of the horizontal spring are first spring guides and second spring guides;

[0009] The first tilt spring is between the first and second rods; the second tilt spring is between the third and fourth rods; the third and fourth spring guides are at both ends of the first tilt spring; the fifth and sixth spring guides are at both ends of the second tilt spring;

[0010] One rod, two rods, three rods and four rods are hinged in sequence to form an M shape, and one rod, two rods, three rods and four rods constitute the leg structure of an arthropod; the horizontal spring constitutes the back muscle of an arthropod, and the first inclined spring and the second inclined spring constitute the leg muscle of an arthropod.

[0011] Furthermore, the one rod and the four rods are connected to the first base and the second base respectively. The third spring guide device is connected to the hinge between the first base and the one rod; the fourth spring guide device is connected to the hinge between the two rods and the three rods; the second tilt spring is fixed to the fifth spring guide device and the sixth spring guide device, the fifth spring guide device is connected to the hinge between the two rods and the three rods, and the sixth spring guide device is connected to the hinge between the four rods and the second base.

[0012] Furthermore, the first spring guide device and the second spring guide device, the third spring guide device and the fourth spring guide device, the fifth spring guide device and the sixth spring guide device constitute three groups of spring guide devices; the rod, the spring guide device and the base are all drilled at the connection to install bearings, and bolts are used to pass through the inner ring of the bearing to connect the various components.

[0013] Furthermore, the stiffness of the first inclined spring and the second inclined spring is k1; the stiffness of the horizontal spring is k2; the load mass simulates the weight of the arthropod body and is located at the hinge of the two middle rods of the M-shaped structure, namely the second rod and the third rod; the vibration-isolated object of the M-shaped structure is the load mass, the mass size is m, and the low-frequency vibration originates from the first base and the second base on the same horizontal plane;

[0014] The length between the hinge points at both ends of the one-bar, two-bar, three-bar, and four-bar is l, and the distance between the support at one end and the symmetry axis of the M-shaped structure is s. Due to the limitation of geometric relationship, the size relationship between s and l must satisfy l <s<2l;

[0015] When the structure has no load mass, the horizontal spring, the first inclined spring, and the second inclined spring are all in their original lengths. The lengths of the first inclined spring and the second inclined spring are l1; the length of the horizontal spring is l2; the relationship between l1 and l2 is:

[0016]

[0017] In the M-type structure, the sizes of l, s, and l1 can be determined according to the installation environment, and l2 can be calculated according to formula (1).

[0018] Furthermore, the bearing capacity of the structure is determined by the horizontal spring; the coordinate y is defined as the displacement of the mass block in the vertical direction, and the coordinate z is defined as the displacement of the foundation in the vertical direction. The origin of the coordinates is the midpoint of the two supports and the positive direction is upward; the displacement of the load mass relative to the foundation can be expressed as x=yz;

[0019] The vertical restoring force f2 generated by the horizontal spring is:

[0020]

[0021] The system is in static equilibrium when x=0. The gravity of the structural load mass is borne by the horizontal spring, that is, mg=f2(x=0). The mass m that the structure can bear is:

[0022]

[0023] After the mass m of the vibration isolation object is determined, the corresponding relationship between the mass m of the vibration isolation object supported by the structure and the stiffness k2 of the horizontal spring is obtained according to formula (2), thereby determining the stiffness k1 of the horizontal spring.

[0024] Furthermore, near x=0, the first inclined spring and the second inclined spring provide equivalent negative stiffness, and the horizontal spring of the M-shaped structure provides equivalent positive stiffness; after combining the two, the total stiffness of the system at x=0 is close to zero; the equivalent stiffness K of the structure is:

[0025]

[0026] At the equilibrium position x = 0, let K = 0 and we can get

[0027]

[0028] When the ratio of the stiffness of the first inclined spring, the second inclined spring and the horizontal spring and the structural parameters satisfy the relationship given in formula (5), the equivalent stiffness of the system at the equilibrium position and the nearby area of ​​the isolated object is close to 0, thereby achieving the effect of low-frequency vibration isolation; according to formula (5), the corresponding relationship between k1 and k2 can be obtained, thereby determining the stiffness k1 of the inclined spring.

[0029] The beneficial effects of the present invention compared with the prior art are:

[0030] The negative stiffness of the bionic M-type quasi-zero stiffness structure of the present invention is provided by an inclined spring, and the positive stiffness is provided by a horizontal spring. The horizontal spring is arranged in a position so that the M-type structure has nonlinear positive stiffness. When the negative stiffness of the M-type structure increases with the increase of displacement, the positive stiffness decreases with the increase of displacement, which expands the range of the positive and negative stiffness offset, so the range of the quasi-zero stiffness is widened. At the same time, the problem that needs to be solved in order to achieve the quasi-zero stiffness of the proposed M-type bionic structure is to provide the relationship between the structural parameters, that is, the quasi-zero stiffness design criteria.

[0031] The present invention broadens the quasi-zero stiffness range, reduces the vibration isolation starting frequency, and improves the vibration isolation performance in the working frequency band. The specific effect can be determined by comparing and analyzing the stiffness-displacement curves and the transmission rate curves of the bionic M-type quasi-zero stiffness structure and the traditional quasi-zero stiffness structure. When the rod length l of the M-type structure is 80mm, the distance s between the support and the symmetry axis of the M-type structure is 120mm, the tilt spring stiffness k1 is 400N / m, the length is 123.7mm, and the horizontal spring length is 144.6mm. According to the quasi-zero stiffness design criteria of the M-type structure, the stiffness of the horizontal spring is calculated to be 31.7N / mm, and the mass that the structure can bear is 70.1g. The corresponding quasi-zero stiffness range of the M-type structure is increased by 23.45%. When the excitation acceleration is 1m / s 2 The response peak of the bionic M-type quasi-zero stiffness structure is at 2.448Hz, which is 16.45% lower than that of the traditional quasi-zero stiffness structure. This verifies that the M-type quasi-zero stiffness structure reduces the starting vibration isolation frequency. At the same time, the M-type structure has better vibration isolation performance in the working frequency band. For example, when f=3Hz, the transmission rate of the M-type quasi-zero stiffness is -42.085dB, which is 6.6dB lower than that of the traditional quasi-zero stiffness structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure provided by an embodiment of the present invention;

[0033] Figure 2 A structural dimension diagram provided for an embodiment of the present invention;

[0034] Figure 3 For articulated specific detail drawings;

[0035] Figure 4 It is the equivalent stiffness-displacement curve diagram of the traditional quasi-zero stiffness structure and the M-type quasi-zero stiffness structure;

[0036] Figure 5 It is the transmissibility curve of the traditional quasi-zero stiffness structure and the M-type quasi-zero stiffness structure;

[0037] Among them, 1-one rod, 2-two rods, 3-three rods, 4-four rods, 5-horizontal spring, 6-first inclined spring, 7-second inclined spring, 8-load mass, 9-first base, 10-second base, 11-first spring guide device, 12-second spring guide device, 13-third spring guide device, 14-fourth spring guide device, 15-fifth spring guide device, 16-sixth spring guide device, 17-bearing, 18-bolt. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail by enumerating examples below. It should be noted that the specific implementation described here is only used to explain the present invention and is not used to limit the present invention.

[0039] The present invention broadens the range of quasi-zero stiffness and improves vibration isolation performance by imitating the geometric nonlinearity of the arthropod structure itself. Figures 1-2 As shown, it mainly consists of four rods, namely, rod 1, rod 2, rod 3, rod 4, a horizontal spring 5, two inclined springs (first inclined spring 6, second inclined spring 7), load mass 8, first base 9 connected to the foundation, and second base 10. Three groups of spring guide devices, first spring guide device 11, second spring guide device 12, third spring guide device 13, fourth spring guide device 14, fifth spring guide device 15, and sixth spring guide device 16, as well as bearings and bolts used for connection. The rods, spring guide devices, and bases are all drilled at the connection to install bearings, and bolts are used to pass through the inner ring of the bearing to connect the various components.

[0040] The specific connection method of the bionic M-type quasi-zero stiffness structure is as follows: Figure 3 As shown, at the connection between the first rod 1, the second rod 2 and the first spring guide device 11, holes are punched in the rod and the spring guide device to install bearings respectively, and the bearing 17 includes 5 coaxial bearings. Finally, the first rod 1, the second rod 2 and the first spring guide device 11 are connected by bolts 18.

[0041] The one rod 1, the second rod 2, the third rod 3, and the fourth rod 4 of the present invention simulate the leg structure of a spider, and the four rods are hinged in sequence to form an M shape. The horizontal spring 5 simulates the back muscles of the spider, the first inclined spring 6 and the second inclined spring 7 simulate the leg muscles of the spring, the stiffness of the first inclined spring 6 and the second inclined spring 7 is k1, and the stiffness of the horizontal spring 5 is k2. The load mass 8 simulates the weight of the arthropod body and is located at the hinge of the two middle rods of the M-shaped structure. The vibration-isolated object of the M-shaped structure is the load mass 8, and the mass size is m. The low-frequency vibration originates from the first base 9 and the second base 10 on the same horizontal plane.

[0042] like Figure 1As shown, the lengths between the hinge points at both ends of the first rod 1, the second rod 2, the third rod 3, and the fourth rod 4 are all l. The distance between one end support and the symmetry axis of the M-shaped structure is s. Due to geometric constraints, the relationship between s and l needs to satisfy l < s < 2l. When the structure has no load mass, the horizontal spring 5, the first inclined spring 6, and the second inclined spring 7 are all in their original length states. The length of the first inclined spring 6 and the second inclined spring 7 is l1; the length of the horizontal spring is l2. The relationship between l1 and l2 is:

[0043]

[0044] In the M-shaped structure, l, s, and l1 can be determined according to the installation environment, and l2 can be calculated according to formula (1).

[0045] The load-bearing capacity of the structure of the present invention is determined by the horizontal spring. Define the coordinate y as the displacement of the mass block in the vertical direction, the coordinate z as the displacement of the foundation in the vertical direction, and the origin of the coordinates is the midpoint of the two supports, and the positive direction is upward. The displacement of the load mass relative to the foundation can be expressed as x = y - z.

[0046] The restoring force f2 generated by the horizontal spring 5 in the vertical direction is:

[0047]

[0048] When x = 0, the system is in the static equilibrium position. The gravity of the vibration isolation object 8 is borne by the horizontal spring, that is, mg = f2(0). The mass m that the structure can bear is

[0049]

[0050] After the mass m of the vibration isolation object is determined, according to formula (3), the corresponding relationship between the mass m of the vibration isolation object borne by the structure and the stiffness k2 of the horizontal spring can be obtained, and thus the stiffness k2 of the horizontal spring is determined.

[0051] In order to achieve quasi-zero stiffness at the equilibrium position of the vibration isolation object, the quasi-zero stiffness design criterion of the M-shaped structure of the present invention is: near x = 0, the first inclined spring 6 and the second inclined spring 7 provide equivalent negative stiffness, while the horizontal spring 5 of the M-shaped structure provides equivalent positive stiffness. After combining the two, the total stiffness of the system at x = 0 is close to zero. The equivalent stiffness K of the structure is:

[0052]

[0053] At the equilibrium position x = 0, let K = 0, and we can get

[0054]

[0055] When the ratio of the stiffness of the first inclined spring 6, the second inclined spring 7 and the horizontal spring 5 and the structural parameters satisfy the relationship given in formula (5), the equivalent stiffness of the system at the equilibrium position and the vicinity of the vibration-isolated object is close to 0, thereby achieving the effect of low-frequency vibration isolation. According to formula (5), the corresponding relationship between k1 and k2 can be obtained, thereby determining the stiffness k1 of the inclined spring.

[0056] When the rod length l of the M-type structure is 80mm, the distance s between the support and the symmetry axis of the M-type structure is 120mm, the tilt spring stiffness k1 is 400N / m, the length l1 is 123.7mm, and the horizontal spring length l2 is 144.6mm. According to the quasi-zero stiffness design criteria of the M-type structure, the stiffness of the horizontal spring k2 is 31.7N / mm, and the mass carried by the structure is 70.1g.

[0057] Figure 4 The stiffness-displacement curves of the M-type quasi-zero stiffness structure and the traditional quasi-zero stiffness structure are given. The length and stiffness of the inclined spring in the M-type structure are consistent with those of the inclined spring in the traditional quasi-zero stiffness. The displacement range corresponding to the equivalent stiffness of the system is defined as the quasi-zero stiffness range when it is less than 1 / 50 of the inclined spring stiffness, that is, 8N / m. At this time, the quasi-zero stiffness range of the traditional three-spring quasi-zero stiffness structure is [-9.69 9.68] mm, and the quasi-zero stiffness width is 19.37 mm; while the quasi-zero stiffness range of the M-type structure is [-14.23 9.684] mm, and the quasi-zero stiffness width is 23.914 mm, which is an increase of 23.45%, verifying that the M-type quasi-zero stiffness structure has a wider quasi-zero stiffness range.

[0058] Figure 5 When the excitation acceleration is 1m / s 2 The transmissibility curves of the M-type quasi-zero stiffness structure and the traditional quasi-zero stiffness structure are shown in Figure 1. The peak response of the traditional quasi-zero stiffness structure is at 2.93Hz, and the peak response of the bionic M-type quasi-zero stiffness structure is at 2.448Hz, which is 16.45% lower than the former. This verifies that the M-type quasi-zero stiffness structure reduces the starting vibration isolation frequency. At the same time, in the frequency band where both have vibration isolation effects, taking f=3Hz as an example, the transmissibility of the traditional quasi-zero stiffness structure is -35.476dB, and the transmissibility of the M-type quasi-zero stiffness is -42.085dB, which is 6.6dB lower than the former. This shows that the M-type structure has better vibration isolation performance in the working frequency band.

[0059] Specific embodiments are listed below:

[0060] This embodiment specifically provides a bionic M-type quasi-zero stiffness low-frequency vibration isolation structure, such as Figure 1As shown, it includes: a rod 1, a second rod 2, a third rod 3, a fourth rod 4, a horizontal spring 5, a first inclined spring 6, a second inclined spring 7, a load mass 8, a first base 9 connected to the foundation, a second base 10, three sets of spring guides, a first spring guide 11, a second spring guide 12, a third spring guide 13, a fourth spring guide 14, a fifth spring guide 15, and a sixth spring guide 16, as well as bearings and bolts used for connection. The rod, spring guide and base are processed by 3D printing, and the material is resin. The spring needs to be customized according to the required length and stiffness. Bolts and bearings use standard parts, so when designing the reserved circular holes at the hinge, attention should be paid to the matching of the circular hole diameter and the selected bearing.

[0061] like Figure 1 As shown, the first rod 1, the second rod 2, the third rod 3, and the fourth rod 4 are connected in sequence, and the other ends of the first rod 1 and the fourth rod 4 are connected to the first base 9 and the second base 10. One end of the horizontal spring 5 is fixed on the first spring guide device 11, and the other end is fixed on the second spring guide device 12;

[0062] The first spring guide device 11 is connected to the hinge of the first rod 1 and the second rod 2, and the second spring guide device 12 is connected to the hinge of the third rod 3 and the fourth rod 4. The first tilt spring 6 is fixed to the third spring guide device 13 and the fourth spring guide device 14. The third spring guide device 13 is connected to the hinge of the first base 9 and the first rod 1, and the fourth spring guide device 14 is connected to the hinge of the second rod 2 and the third rod 3. The second tilt spring 7 is fixed to the fifth spring guide device 15 and the sixth spring guide device 16. The fifth spring guide device 15 is connected to the hinge of the second rod 2 and the third rod 3, and the sixth spring guide device 16 is connected to the hinge of the fourth rod 4 and the second base 10. The load mass 8 is installed at the hinge of the second rod 2 and the third rod 3. The connection methods of the bionic M-shaped structure are as follows. Figure 2 As shown in the figure, holes are reserved at the hinges and bearings are installed in the holes. Spacers are placed between each contact surface to reduce the contact area, and finally bolts are used to connect.

[0063] like Figure 1As shown in the figure, the lengths between the hinge points of the first rod 1, the second rod 2, the third rod 3, and the fourth rod 4 are all l, and the distance between one end support and the symmetry axis of the M-shaped structure is s. Due to the limitation of geometric relationships, the size relationship between s and l needs to satisfy l < s < 2l; when there is no load on the structure, the horizontal spring 5, the first inclined spring 6, and the second inclined spring 7 are all in their original length states. The lengths of the first inclined spring 6 and the second inclined spring 7 are l1, and the length of the horizontal spring is l2. After the installation environment and the vibration isolation object are determined, l, s, l1, and m in the structural parameters are determined fixed values. The stiffness k2 of the horizontal spring 5 is calculated from the formula (3) according to the determined structural parameters. The stiffness k1 of the first inclined spring 6 and the second inclined spring 7 is calculated according to the formula (5).

[0064] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements can be made, and these improvements should also be regarded as the protection scope of the present invention.

Claims

1. An M-type low-frequency vibration isolation structure imitating the leg structure of an arthropod, characterized in that: The structure is an arthropod-like structure; it comprises four rods connected in sequence, namely, a first rod (1), a second rod (2), a third rod (3), and a fourth rod (4); a horizontal spring (5) is provided between the connection points of the first rod (1), the second rod (2), the third rod (3), and the fourth rod (4); and two ends of the horizontal spring (5) are a first spring guide device (11) and a second spring guide device (12); The first spring guide device (11) is connected to the hinge of the first rod (1) and the second rod (2), and the second spring guide device (12) is connected to the hinge of the third rod (3) and the fourth rod (4); the first inclined spring (6) is between the first rod (1) and the second rod (2); the second inclined spring (7) is between the third rod (3) and the fourth rod (4); The two ends of the first inclined spring (6) are a third spring guide device (13) and a fourth spring guide device (14); The two ends of the second inclined spring (7) are a fifth spring guide device (15) and a sixth spring guide device (16); The load mass (8) is installed at the hinge between the second rod (2) and the third rod (3); One rod (1), two rods (2), three rods (3), and four rods (4) constitute an M-shaped leg structure similar to that of an arthropod; a horizontal spring (5) constitutes back muscles similar to that of an arthropod, and a first inclined spring (6) and a second inclined spring (7) constitute leg muscles similar to that of an arthropod.

2. The M-type low-frequency vibration isolation structure imitating the leg structure of an arthropod according to claim 1, characterized in that: The other ends of the one rod (1) and the four rods (4) are connected to the first base (9) and the second base (10) respectively; the third spring guide device (13) is connected to the hinge between the first base (9) and the one rod (1); the fourth spring guide device (14) is connected to the hinge between the two rods (2) and the three rods (3); the second inclined spring (7) is fixed to the fifth spring guide device (15) and the sixth spring guide device (16); the fifth spring guide device (15) is connected to the hinge between the two rods (2) and the three rods (3), and the sixth spring guide device (16) is connected to the hinge between the four rods (4) and the second base (10).

3. The M-type low-frequency vibration isolation structure imitating the leg structure of an arthropod according to claim 1, characterized in that: The first spring guide device (11), the second spring guide device (12), the third spring guide device (13), the fourth spring guide device (14), the fifth spring guide device (15) and the sixth spring guide device (16) constitute three groups of spring guide devices; the rod, the spring guide device and the base are all drilled at the connection to install bearings (17), and bolts (18) are used to pass through the inner ring of the bearing to connect the various components.

4. The M-type low-frequency vibration isolation structure imitating the leg structure of an arthropod according to claim 1, characterized in that: The stiffness of the first inclined spring (6) and the second inclined spring (7) is k1; the stiffness of the horizontal spring (5) is k2; the load mass (8) simulates the weight of the arthropod body and is located at the hinge of the two middle rods of the M-shaped structure, namely the second rod (2) and the third rod (3); the vibration-isolated object of the M-shaped structure is the load mass (8), the mass size is m, and the low-frequency vibration originates from the first base (9) and the second base (10) on the same horizontal plane; The length between the hinge points at both ends of the one-bar (1), two-bar (2), three-bar (3), and four-bar (4) is l, and the distance between the support at one end and the symmetry axis of the M-shaped structure is s. Due to the limitation of geometric relationship, the size relationship between s and l must satisfy l <s<2l; When the structure has no load mass, the horizontal spring (5), the first inclined spring (6), and the second inclined spring (7) are all in their original length states, and the length of the first inclined spring (6) and the second inclined spring (7) is l1; The length of the horizontal spring (5) is l2; the relationship between l1 and l2 is: In the M-type structure, the sizes of l, s, and l1 can be determined according to the installation environment, and l2 can be calculated according to formula (1).

5. The M-type low-frequency vibration isolation structure imitating the leg structure of an arthropod according to claim 1, characterized in that: The bearing capacity of the structure is determined by the horizontal spring (5); the coordinate y is defined as the displacement of the mass block in the vertical direction, and the coordinate z is defined as the displacement of the foundation in the vertical direction. The origin of the coordinates is the midpoint of the two supports and the positive direction is upward; the displacement of the load mass (8) relative to the foundation can be expressed as x=yz; The restoring force f2 in the vertical direction generated by the horizontal spring (5) is: The system is in static equilibrium when x = 0. The gravity of the structural load mass (8) is borne by the horizontal spring, that is, mg = f2(0). The mass m that the structure can bear is: After the mass m of the vibration isolation object is determined, the corresponding relationship between the mass m of the vibration isolation object supported by the structure and the stiffness k2 of the horizontal spring is obtained according to formula (3), thereby determining the stiffness k2 of the horizontal spring.

6. The M-type low-frequency vibration isolation structure imitating the leg structure of an arthropod according to claim 1, characterized in that: Near x=0, the first inclined spring (6) and the second inclined spring (7) provide equivalent negative stiffness, and the horizontal spring (5) of the M-shaped structure provides equivalent positive stiffness. After combining the two, the total stiffness of the system at x=0 is close to zero. The equivalent stiffness K of the structure is: At the equilibrium position x = 0, let K = 0 and we can get When the ratio of the stiffness of the first inclined spring (6), the second inclined spring (7) and the horizontal spring (5) and the structural parameters satisfy the relationship given in formula (5), the equivalent stiffness of the system at the equilibrium position of the isolated object and the nearby area is close to 0, thereby achieving the effect of low-frequency vibration isolation; according to formula (5), the corresponding relationship between k1 and k2 can be obtained, thereby determining the stiffness k1 of the inclined spring.

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