Vibration isolation system and relative gravimeter

Abstract

This application relates to a vibration isolation system and a relative gravimeter. The vibration isolation system includes a base, a pendulum, and a magnetic levitation device. The magnetic levitation device includes two first magnets and a second magnet. The vibration isolation system of this application achieves near-zero stiffness by using a uniform magnetic field generated by each of the first magnets, ensuring that the second magnet experiences equal force everywhere within this uniform magnetic field. Furthermore, the static magnetic force generated by each first magnet on the second magnet balances the effective load of the second magnet and the pendulum, thus resolving the contradiction between load and vibration isolation—that is, the greater the load, the weaker the vibration isolation effect.

Description

Technical Field

[0001] This application relates to the field of measurement technology, and in particular to a vibration isolation system and a relative gravimeter. Background Technology

[0002] Gravitational acceleration is a crucial physical quantity in astrophysics and celestial mechanics. It is significant for understanding the origin and evolution of the universe, as well as in astrophysics and planetary science. The determination of gravitational acceleration typically involves measuring the displacement of a falling object relative to a reference prism and the time interval between these measurements to obtain the gravitational acceleration at the measurement point. However, ground vibrations can interfere with the reference prism during the measurement process, thus affecting the accuracy of the measurement.

[0003] In practical applications, vibration isolation devices with elastic structures of finite stiffness (such as springs) are typically used to reduce the interference of ground vibration on the reference prism when measuring gravitational acceleration.

[0004] However, using elastic structures for vibration isolation presents a contradiction between load and vibration isolation. Summary of the Invention

[0005] Therefore, it is necessary to provide a vibration isolation system and a relative gravimeter that can resolve the contradiction between load and vibration isolation in order to address the above-mentioned technical problems.

[0006] In a first aspect, this application provides a vibration isolation system. The vibration isolation system includes: a base, a pendulum rod, and a magnetic levitation device;

[0007] The pendulum is connected to the base, and the pendulum is parallel to the base;

[0008] The magnetic levitation device includes two first magnets and a second magnet. One first magnet is located on the side of the pendulum rod close to the base, and the other first magnet is located on the other side of the pendulum rod away from the base. The second magnet is located on the surface of the pendulum rod and between the two first magnets.

[0009] A uniform magnetic field is formed between the two first magnets, and the magnetic force generated by each first magnet on the second magnet is opposite to the direction of the gravity of the pendulum rod; the magnetic force is used to balance the effective load, which includes the second magnet and the pendulum rod.

[0010] In one embodiment, the two first magnets are the same size, and the size of the two first magnets is larger than the size of the second magnet.

[0011] In one embodiment, the two first magnets are identical in shape, and the two first magnets are any one of a ring magnet, a cylindrical magnet, and a wedge magnet.

[0012] In one embodiment, the second magnet is a cylindrical magnet.

[0013] In one embodiment, the vibration isolation system further includes a first coil wound around the surface of a first magnet;

[0014] The first coil is used to generate a changing first magnetic field, which in turn provides force to the second magnet.

[0015] In one embodiment, the vibration isolation system further includes a second coil wound around the surface of the second magnet;

[0016] The second coil is used to generate a changing second magnetic field, which in turn provides force to the second magnet.

[0017] In one embodiment, the second coil is a Helmholtz coil.

[0018] In one embodiment, the vibration isolation system further includes a displacement detection device and an adjustment device. The displacement detection device is disposed between the swing arm and the base, and the adjustment device is disposed between the swing arm and the base. The displacement detection device and the adjustment device are connected.

[0019] The displacement detection device is used to detect the displacement of the pendulum rod and transmit the displacement to the adjustment device;

[0020] The adjustment device is used to apply a compensating force to the pendulum based on the displacement, and the compensating force is used to move the pendulum to the equilibrium position.

[0021] In one embodiment, the vibration isolation adjustment device includes a voice coil motor.

[0022] In one embodiment, the vibration isolation system further includes a filter circuit, the input of which is connected to the displacement detection device, and the output of which is connected to the adjustment device.

[0023] In one embodiment, the vibration isolation system further includes a flexible connector disposed between the swing arm and the base for connecting the swing arm and the base.

[0024] In one embodiment, the flexible connector includes a flexible hinge.

[0025] Secondly, this application also provides a relative gravimeter. The relative gravimeter includes: a reference prism and the vibration isolation system described in the first aspect; the reference prism is disposed on the pendulum rod of the vibration isolation system.

[0026] The aforementioned vibration isolation system and relative gravimeter include: a base, a pendulum, and a magnetic levitation device; the pendulum is connected to the base and is parallel to the base; the magnetic levitation device includes two first magnets and a second magnet, one first magnet being disposed on the side of the pendulum closer to the base and the other first magnet being disposed on the side of the pendulum farther from the base; the second magnet is disposed on the surface of the pendulum and located between the two first magnets; a uniform magnetic field is formed between the two first magnets, and the magnetic force generated by each first magnet on the second magnet is opposite to the direction of gravity of the pendulum; the magnetic force is used to balance the effective load, which includes the second magnet and the pendulum. The vibration isolation system of this application embodiment achieves near-zero stiffness by using the uniform magnetic field generated by each first magnet to ensure that the second magnet experiences equal force everywhere in the uniform magnetic field. Furthermore, the static magnetic force generated by each first magnet on the second magnet can balance the effective load of the second magnet and the pendulum, thereby solving the contradiction between load and vibration isolation, i.e., the problem that the greater the load, the weaker the vibration isolation effect. Attached Figure Description

[0027] Figure 1 This is one of the schematic diagrams illustrating vibration isolation based on near-zero stiffness using permanent magnets in related technologies;

[0028] Figure 2 This is the second schematic diagram of vibration isolation based on near-zero stiffness using permanent magnets in related technologies;

[0029] Figure 3 This is a schematic diagram of an approximately zero-stiffness system based on a ring-shaped permanent magnet in related technologies;

[0030] Figure 4 This is a schematic diagram of a vibration isolation system in one embodiment;

[0031] Figure 5 This is a schematic diagram of the vibration isolation system in another embodiment;

[0032] Figure 6 This is a schematic diagram of a relative gravimeter in one embodiment.

[0033] Figure label:

[0034] Vibration isolation device: vibration isolation system 1; relative gravimeter 2; base 11; pendulum 12; magnetic levitation device 13; counterweight 14; displacement detection module 15; adjustment module 16; flexible connector 17; reference prism 18; first magnet 131; second magnet 132; reflector 151; beam splitter 151; photodetector 153; laser 154; voice coil motor 161. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0036] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0037] Furthermore, in the description of this application, the term "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0039] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0040] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0041] First, before introducing the technical solutions of the embodiments of this application in detail, the technical background on which the embodiments of this application are based will be introduced.

[0042] During the measurement of gravitational acceleration, ground vibrations can interfere with the reference prism, thus affecting measurement accuracy. Ultra-low frequency vertical vibration isolation systems can reduce the impact of ground vibrations on the reference prism, providing an inertial reference point for the system.

[0043] like Figure 1 As shown, in terms of vibration isolation based on near-zero stiffness of permanent magnets, there are currently methods that utilize paired permanent magnets to achieve six-degree-of-freedom vibration isolation. This involves using two ring magnets, one above the other, to create a magnetic field with a uniform central gradient. Figure 2 As shown, the central magnet experiences a force in a region with an approximate slope of zero in the middle. The experimental and theoretical resonant frequencies of the system in the X, Y, and Z directions are approximately 2.9 Hz, 3 Hz, 1.8 Hz and 3 Hz, 3 Hz, 1.6 Hz, respectively. However, this technique suffers from insufficient period length.

[0044] Near-zero stiffness systems based on toroidal permanent magnets, such as Figure 3 As shown, the principle is to use two axially magnetized magnetic rings to generate negative stiffness. The final vibration isolation frequency obtained by this system is about 15Hz. The vibration isolation frequency of this system is too high, and the use of elastic materials for vibration isolation creates a design contradiction between load-bearing capacity and vibration isolation performance, resulting in a short cycle of the vibration isolation system.

[0045] Alternatively, quasi-zero stiffness can be achieved by using linear electromagnetic springs (LES) in parallel with a traditional linear isolation system. The LES can generate linear negative stiffness to balance the positive stiffness of the traditional system, and its natural frequency can be tuned from 10Hz to as low as 2Hz. However, this system, which uses elastic materials for vibration isolation, presents a trade-off between stiffness and load.

[0046] As can be seen from the above-mentioned technologies, traditional passive vibration isolation devices often use finite stiffness elastic structures, which require complex geometric structures to solve the design contradiction between load-bearing capacity and vibration isolation performance, and also have shortcomings in temperature characteristics.

[0047] Based on this, this application provides a vibration isolation system and a relative gravimeter, aiming to solve the above-mentioned technical problems.

[0048] In one embodiment, such as Figure 4 As shown, a vibration isolation system 1 is provided, which includes: a base 11, a swing rod 12 and a magnetic levitation device 13.

[0049] The connection between the swing arm 12 and the base 11 can be optionally achieved through a hinge, riveting, or bearing. This embodiment does not specifically limit the connection method between the swing arm 12 and the base 11. The swing arm 12 is horizontally positioned and parallel to the base 11 and the ground. Springs or similar devices can be added to the swing arm 12 to increase its rigidity.

[0050] The magnetic levitation device 13 includes two first magnets 131 and a second magnet 132. In this embodiment, the first magnet 131 and the second magnet 132 are permanent magnets. The first magnet 131 may include one of a ring magnet, a cylindrical magnet, or a wedge magnet. The second magnet 132 may include a circular magnet or a cylindrical magnet.

[0051] One first magnet 131 is located on the side of the pendulum 12 closest to the base 11, and the other first magnet 131 is located on the other side of the pendulum 12 away from the base 11. That is, one first magnet 131 is above the second magnet 132, and the other first magnet 131 is below the second magnet 132. The first magnet 131 can be supported on the ground by pillars. This application does not specify the number of pillars. The second magnet 132 is located on the surface of the pendulum 12, between the two first magnets 131. The spacing can also be adjusted by adding or removing shims between the pillars and the upper and lower bases to adjust the force range and the instrument's stiffness. In the magnetic field of this structure, especially within the working range, the force exhibits excellent linearity.

[0052] Two first magnets 131 are used to form a uniform magnetic field, so that the second magnet 132 experiences the same force everywhere in the uniform magnetic field. Moreover, the magnetic force generated by each first magnet 131 on the second magnet 132 is opposite to the direction of the gravity of the pendulum 12.

[0053] Optionally, the N-pole of the first magnet 131 above the second magnet 132 faces upward and the S-pole faces downward; the N-pole of the first magnet 131 below the second magnet 132 faces downward and the S-pole faces upward; and the N-pole of the second magnet 132 in the middle faces upward and the S-pole faces downward. This makes the upper first magnet 131 and the second magnet 132 have the same polarization, generating an attractive force on the second magnet 132. Meanwhile, the lower first magnet 131 has the opposite magnetization direction to the second magnet 132, generating a repulsive force on the second magnet 132, thus exerting an upward force on the second magnet 132.

[0054] According to the formula for the force experienced by a magnetic dipole (the second magnet 132 in this embodiment) in a magnetic field, the force experienced by the magnetic dipole is equal everywhere in a magnetic field with a uniform gradient. In this magnetic field, a second magnet 132 is placed such that the magnetic force experienced by it is balanced by its own force, the pendulum 12, and the required devices, that is, the effective restoring force is zero everywhere.

[0055] The aforementioned vibration isolation system includes a base, a pendulum, and a magnetic levitation device. The pendulum is connected to the base and is parallel to it. The magnetic levitation device includes two first magnets and a second magnet. One first magnet is located on the side of the pendulum closer to the base, and the other is located on the side of the pendulum farther from the base. The second magnet is located on the surface of the pendulum and between the two first magnets. A uniform magnetic field is formed between the two first magnets, and the magnetic force generated by each first magnet on the second magnet is opposite to the direction of the gravity of the pendulum. The magnetic force is used to balance the effective load, which includes the second magnet and the pendulum. The vibration isolation system of this embodiment achieves near-zero stiffness by using the uniform magnetic field generated by each first magnet to ensure that the second magnet experiences equal force everywhere in the uniform magnetic field. Furthermore, the static magnetic force generated by each first magnet on the second magnet can balance the effective load of the second magnet and the pendulum, thereby solving the contradiction between load and vibration isolation, i.e., the problem that the greater the load, the weaker the vibration isolation effect.

[0056] In another embodiment, based on the above embodiment, the two first magnets 131 are the same size, and the size of the two first magnets 131 is larger than the size of the second magnet 132.

[0057] In this embodiment, the first magnet 131 is set to a larger size, and the second magnet 132 is set to a smaller size. This is to enable the first magnet 131 to generate a larger magnetic force, thereby balancing the gravity of the second magnet 132, the pendulum 12, and the counterweight 14. The specific sizes of the first magnet 131 and the second magnet 132 are determined by actual needs.

[0058] In the aforementioned vibration isolation system, the two first magnets are of the same size, which allows the first magnets to generate a uniformly gradient magnetic field. This ensures that the second magnets within the system are uniformly sized, achieving near-zero stiffness and effectively extending the vibration isolation period. Setting the size of the two first magnets to be larger than the size of the second magnet allows the magnetic force generated by the first magnets to balance the gravity of the second magnet, the pendulum rod, and the counterweight.

[0059] In one embodiment, the two first magnets 131 have the same shape, and the two first magnets 131 are any one of ring magnets, cylindrical magnets, and wedge magnets.

[0060] In this embodiment, since the first magnet 131 is a permanent magnet, it is theoretically known that a permanent magnet can generate a uniform magnetic field. Arranging two first magnets 131 of the same shape together can generate a magnetic field with a uniform gradient. The shape of the first magnet 131 can be various, including any one of ring magnets, cylindrical magnets, and wedge magnets. The specific shape of the first magnet 131 used is determined by actual needs.

[0061] The vibration isolation system 1 described above sets the two first magnets 131 to have the same shape, so that the first magnets 131 generate a magnetic field with a uniform gradient, thereby making the second magnets 132 therein equal everywhere, thus achieving near-zero stiffness and effectively extending the vibration isolation period.

[0062] In another embodiment, the type of the first magnet 131 can be varied and highly adaptable.

[0063] In one embodiment, the vibration isolation system 1 further includes a first coil wound around the surface of the first magnet 131.

[0064] In this embodiment, the first coil includes, but is not limited to, a Helmholtz coil, a saddle-shaped coil, or a coil capable of generating a uniform magnetic field. The generated uniform magnetic field is a first magnetic field that can vary. The first coil can be wound around the surface of the first magnet 131 or around either of the two second magnets 132; this embodiment does not impose specific limitations.

[0065] The vibration isolation system 1 described above also includes a first coil, which can generate a first magnetic field of uniform intensity. The first coil is wound around the surface of the first magnet 131. The first magnetic field can provide force to the second magnet 132, which can make the second magnet 132 obtain a better force curve.

[0066] In one embodiment, the vibration isolation system 1 further includes a second coil wound around the surface of the second magnet 132.

[0067] The second coil includes, but is not limited to, a Helmholtz coil, a saddle-shaped coil, or other coils capable of generating a uniform magnetic field. The generated uniform magnetic field can produce a varying second magnetic field. The second coil can be wound around the first magnet 131. Optionally, the second coil can be wound around both first magnets.

[0068] The vibration isolation system described above also includes a second coil, which can generate a second magnetic field of uniform intensity. The second coil is wound around the surface of the second magnet, and the second magnetic field can provide force to the first magnet, allowing the second magnet to obtain a better force curve.

[0069] In another embodiment, the second coil is a Helmholtz coil.

[0070] Among them, the Helmholtz coil is used to generate the magnetic field of a device that produces an almost uniform region, which can produce a region with a magnetic field strength closer to zero.

[0071] like Figure 5 As shown, the force change on the second magnet 132 is only on the order of a small magnitude over a relatively long range, thus basically meeting the vibration isolation requirements. Helmholtz coils can be added to either the upper or lower first magnet 131 or the second magnet 132 to obtain a better force curve or for compensation. Using a Helmholtz coil to fine-tune the magnetic field when the second magnet 132 deviates from the center can make the force at the off-center position closer to the force at the center position, thus expanding the working range and obtaining a better force curve. Simultaneously, energizing the coil wound on the first magnet 131 can generate a changing magnetic field through feedback control of the current flowing through the coil, fine-tuning the force on the second magnet 132 for compensation.

[0072] In the aforementioned vibration isolation system, setting the second coil as a Helmholtz sub-coil allows the second magnet to obtain a better force curve or to be compensated, thereby further improving the vibration isolation capability of the vibration isolation system.

[0073] In another embodiment, such as Figure 6 As shown, the vibration isolation system 1 also includes a displacement detection device 15 and an adjustment device 16.

[0074] In this embodiment, the displacement detection device 15 is a photoelectric detection circuit, disposed between the pendulum rod 12 and the base 11. The photoelectric detection circuit includes a reflector 151, a beam splitter 152, a photodetector 153, and a laser 154. The reflector 151 is disposed below the pendulum rod 12, and the beam splitter 152 and the four-quadrant photodetector 153 are disposed directly below the reflector 151. The four-quadrant photodetector 153 is disposed on the base 11, and the beam splitter 152 is disposed on the four-quadrant photodetector 153. The laser 154 is disposed on one side of the photodetector 153. The displacement detection device 15 is used to detect the displacement of the pendulum rod 12 and transmit the displacement to the adjustment device 16. The adjustment device 16 is used to apply a compensation force to the pendulum rod 12 according to the displacement, and the compensation force is used to move the pendulum rod 12 to the equilibrium position.

[0075] Optionally, the detector is a four-quadrant photodetector, which can accurately measure the motion state of an object.

[0076] Specifically, the laser 154 outputs a probe beam, which passes through the beam splitter 152 to the reflector 151. The probe beam then travels through the reflector 151 to the four-quadrant photodetector 153. Thus, if the pendulum 12 swings, the probe beam on the four-quadrant photodetector 153 will move. The displacement of the pendulum 12 can be calculated from the output of the four-quadrant photodetector 153. The photodetector 153 then transmits the displacement of the pendulum 12 to the adjustment device 16. The adjustment device 16 applies a compensating force to the pendulum 12 based on the displacement, causing the pendulum 12 to move to its equilibrium position.

[0077] The aforementioned vibration isolation system also includes a displacement detection device and an adjustment device. Based on the four-quadrant photoelectric detector in the displacement detection device, the displacement of the pendulum can be accurately calculated. Thus, the adjustment device can adjust the pendulum according to the displacement of the pendulum to compensate for the drift of the vibration isolation system, thereby further improving the vibration isolation capability of the vibration isolation system.

[0078] In another embodiment, see continue to see Figure 6 As shown, the vibration isolation adjustment device 16 includes a voice coil motor 161.

[0079] Among them, the voice coil motor 161 is a special type of direct drive motor. It features simple structure, small size, high speed, and fast response. Its working principle is that when a current-carrying coil (conductor) is placed in a magnetic field, a force is generated, the magnitude of which is proportional to the current applied to the coil.

[0080] In this embodiment, the vibration isolation adjustment device 16 uses a voice coil motor 161, which can generate a corresponding force based on the displacement of the pendulum 12 when it receives the displacement of the pendulum 12 output by the four-quadrant photodetector 153, and apply it to the pendulum 12.

[0081] The vibration isolation system described above uses a voice coil motor for its vibration isolation adjustment device. This motor is characterized by its simple structure, small size, high speed, and fast response. It can quickly adjust the displacement of the swing arm 12 by generating a corresponding force through the displacement of the swing arm.

[0082] In another embodiment, the vibration isolation system 1 further includes a filter circuit, the input of which is connected to the displacement detection device 15, and the output of which is connected to the adjustment device 16.

[0083] The filter circuit includes a PI (Power Integrity) circuit, which is connected to the photoelectric detection circuit and the voice coil motor 161.

[0084] In this embodiment, the PI circuit filters and amplifies the displacement signal received from the displacement detection device 15, and then transmits it to the voice coil motor 161.

[0085] The vibration isolation system described above also includes a filter circuit. The filter circuit can filter and amplify the received displacement signal, thereby making the displacement signal received by the voice coil motor more accurate.

[0086] In another embodiment, see continue to see Figure 6 As shown, the vibration isolation system 1 also includes a flexible connector 17, which is disposed between the swing arm 12 and the base 11 and is used to connect the swing arm 12 and the base 11.

[0087] The flexible connector 17 can be a hinge connection, a snap ring connection, a spring connection, etc. The flexible connector 17 can connect the swing arm 12 and the base 11, so that the swing arm 12 can move in the vertical direction.

[0088] The aforementioned vibration isolation system, by placing a flexible connector between the pendulum and the base, can restrict the pendulum to only perform one-dimensional motion, thereby limiting the system to only one degree of freedom in the vertical direction. This can reduce errors caused by other degrees of freedom.

[0089] In another embodiment, see continue to see Figure 6 As shown, the flexible connector 17 includes a flexible hinge.

[0090] Among them, the flexible hinge is a simple and relatively regular elastic support with a rotation center that coincides with the geometric central axis. It works by relying on the limited deformation of elastic sheets evenly distributed radially around the circumference. Under torsional load, it generates rotational motion around its rotation center within a limited angular range.

[0091] The flexible connector 17 in this embodiment adopts a flexible hinge, and the swing arm 12 can be connected to the base 11 through the flexible hinge, so that the swing arm 12 can move in the vertical direction.

[0092] The aforementioned vibration isolation system uses flexible hinges for the flexible connectors, meaning that the pendulum and the base are connected by flexible hinges. This allows for no mechanical friction between the pendulum and the base during rotation, thereby reducing system errors during the balancing process.

[0093] Secondly, embodiments of this application also provide a relative gravimeter 2. (See also...) Figure 6 As shown, the aforementioned relative gravimeter 2 includes: a reference prism 18 and the vibration isolation system 1 described in the first aspect; the vibration isolation system 1 is as follows: Figure 6As shown, the system includes: a base 11, a pendulum 12, and a magnetic levitation device 13; the pendulum 12 is connected to the base 11 and is parallel to the base 11; the magnetic levitation device 13 includes two first magnets 131 and a second magnet 132, one first magnet 131 is disposed on the side of the pendulum 12 near the base 11, and the other first magnet 131 is disposed on the other side of the pendulum 12 away from the base 11; the second magnet 132 is disposed on the surface of the pendulum 12 and is located between the two first magnets 131; a uniform magnetic field is formed between the two first magnets 131, and the magnetic force generated by each first magnet 131 on the second magnet 132 is opposite to the direction of the gravity of the pendulum 12; the magnetic force is used to balance the effective load, which includes the second magnet 132 and the pendulum 12. A reference prism 18 is disposed on the pendulum 12 in the vibration isolation system 1.

[0094] The aforementioned relative gravimeter includes a reference prism and a vibration isolation system. In this embodiment, the vibration isolation system utilizes the uniform magnetic field generated by each first magnet to ensure that the second magnet experiences equal force throughout the magnetic field, thus achieving near-zero stiffness. Furthermore, the static magnetic force generated by each first magnet on the second magnet balances the effective load of the second magnet and the pendulum rod, thereby resolving the contradiction between load and vibration isolation—specifically, the problem that the greater the load, the weaker the vibration isolation effect. Simultaneously, by using the vibration isolation system of this application to isolate the reference prism, the impact on the stability of the reference prism can be reduced when ground vibrations occur, thereby ensuring the measurement accuracy of the relative gravimeter.

[0095] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A vibration isolation system, characterized in that, The vibration isolation system includes: a base, a pendulum rod, and a magnetic levitation device; The swing arm is connected to the base, and the swing arm is parallel to the base; The magnetic levitation device includes two first magnets and a second magnet. One first magnet is disposed on the side of the pendulum rod close to the base, and the other first magnet is disposed on the other side of the pendulum rod away from the base. The second magnet is disposed on the surface of the pendulum rod and is located between the two first magnets. A uniform magnetic field is formed between the two first magnets, and the magnetic force generated by each first magnet on the second magnet is opposite to the direction of the gravity of the pendulum rod; the magnetic force is used to balance the effective load, which includes the second magnet and the pendulum rod.

2. The vibration isolation system according to claim 1, characterized in that, The two first magnets are the same size, and the size of the two first magnets is larger than the size of the second magnet.

3. The vibration isolation system according to claim 1, characterized in that, The two first magnets are identical in shape, and the two first magnets are any one of ring magnets, cylindrical magnets, and wedge magnets.

4. The vibration isolation system according to claim 1, characterized in that, The second magnet is a cylindrical magnet.

5. The vibration isolation system according to any one of claims 1-4, characterized in that, The vibration isolation system also includes a first coil wound around the surface of the first magnet; The first coil is used to generate a changing first magnetic field, which is used to provide force to the second magnet.

6. The vibration isolation system according to any one of claims 1-4, characterized in that, The vibration isolation system also includes a second coil wound around the surface of the second magnet; The second coil is used to generate a changing second magnetic field, which in turn provides force to the second magnet.

7. The vibration isolation system according to claim 6, characterized in that, The second coil is a Helmholtz secondary coil.

8. The vibration isolation system according to any one of claims 1-4, characterized in that, The vibration isolation system further includes a displacement detection device and an adjustment device. The displacement detection device is disposed between the swing arm and the base, and the adjustment device is disposed between the swing arm and the base. The displacement detection device is connected to the adjustment device. The displacement detection device is used to detect the displacement of the swing arm and transmit the displacement to the adjustment device; The adjustment device is used to apply a compensating force to the pendulum rod according to the displacement, and the compensating force is used to move the pendulum rod to the equilibrium position.

9. The vibration isolation system according to claim 8, characterized in that, The adjustment device includes a voice coil motor.

10. The vibration isolation system according to claim 8, characterized in that, The vibration isolation system also includes a filter circuit, the input of which is connected to the displacement detection device, and the output of which is connected to the adjustment device.

11. The vibration isolation system according to any one of claims 1-4, characterized in that, The vibration isolation system also includes a flexible connector disposed between the swing arm and the base for connecting the swing arm and the base.

12. The vibration isolation system according to claim 11, characterized in that, The flexible connector includes a flexible hinge.

13. A relative gravimeter, characterized in that, The relative gravimeter includes: a reference prism and a vibration isolation system as described in any one of claims 1-12; The reference prism is mounted on the pendulum in the vibration isolation system.

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