Seismometer based on inverted pendulum structure and capacitive displacement sensor
By combining an inverted pendulum structure with a capacitive displacement sensor, a differential capacitance sensor was constructed, which solved the problem of low measurement accuracy of seismographs and enabled high-precision detection of low-frequency signals and measurement of rotational degrees of freedom.
Patent Information
- Application Number
- CN202522106277.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-29
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-09-29
AI Technical Summary
Existing seismographs have low measurement sensitivity, making it impossible to obtain high-precision seismic noise measurement results, which affects measurement accuracy.
The design employs an inverted pendulum structure and a capacitive displacement sensor. Differential capacitance sensors are used to construct first and second capacitors. The displacement and rotation of the metal mass block are obtained by detecting the change in capacitance. Magnetic components are combined to reduce noise and improve measurement accuracy.
It exhibits minimal noise around 1 Hz, improving measurement accuracy and demonstrating excellent sensitivity to low-frequency signals. It can detect low-frequency signals and expand its application range to the measurement of rotational degrees of freedom.
Smart Images
Figure CN224682414U_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of terminal technology, and in particular to a seismograph based on an inverted pendulum structure and a capacitive displacement sensor. Background Technology
[0002] In the field of high-precision measurement, seismic noise often directly affects the accuracy of measurements, and the accuracy of seismic noise measurement also affects the measurement results. Existing measurement technologies have relatively low sensitivity and cannot obtain high-precision seismic noise measurement results. Utility Model Content
[0003] This disclosure provides a seismograph based on an inverted pendulum structure and a capacitive displacement sensor to address the shortcomings of related technologies.
[0004] According to embodiments of this disclosure, a seismograph is provided, comprising:
[0005] Square frame;
[0006] A base plate, which is disposed on the bottom side of the square frame;
[0007] A flexible support rod, which is connected to the base plate and located within the square frame;
[0008] First capacitor plate;
[0009] The second capacitor plate, the first capacitor plate and the second capacitor plate are disposed inside the square frame and are disposed opposite to each other in a first direction;
[0010] A metal mass block is connected to one end of the flexible support rod away from the base plate, and the metal mass block is located between the first capacitor plate and the second capacitor plate. The metal mass block and the first capacitor plate form a first capacitor, and the metal mass block and the second capacitor plate form a second capacitor. The initial capacitance values of the first capacitor and the second capacitor are equal.
[0011] A power source, which is electrically connected to the metal mass block;
[0012] The processor is electrically connected to the first capacitor plate and the second capacitor plate respectively, and the processor is used to obtain the displacement of the metal mass block in a first direction based on the initial capacitance and capacitance change of the first capacitor and the second capacitor.
[0013] Optional, also includes:
[0014] The third capacitor plate, the first capacitor plate and the third capacitor plate are arranged side by side with a gap in the vertical direction;
[0015] The fourth capacitor plate, the third capacitor plate and the fourth capacitor plate are disposed inside the square frame and are disposed opposite to each other in the second direction. The second capacitor plate and the fourth capacitor plate are spaced apart and arranged side by side in the vertical direction, and the vertical direction is parallel to the length direction of the flexible support rod.
[0016] The metal mass block is located between the third capacitor plate and the fourth capacitor plate. The metal mass block forms a third capacitor with the third capacitor plate and a fourth capacitor with the fourth capacitor plate. The initial capacitance values of the third capacitor and the fourth capacitor are equal.
[0017] The processor is electrically connected to the third capacitor plate and the fourth capacitor plate respectively. The processor is used to obtain the displacement of the metal mass block in a first direction and the rotation in a second direction based on the initial capacitance and capacitance change of the first capacitor and the second capacitor, and the initial capacitance and capacitance change of the first capacitor and the second capacitor, wherein the second direction, the first direction and the vertical direction are perpendicular to each other.
[0018] Optional, also includes:
[0019] Fifth capacitor board;
[0020] The sixth capacitor plate, the fifth capacitor plate and the sixth capacitor plate are disposed inside the square frame and are disposed opposite to each other in the second direction. The metal mass block is located between the fifth capacitor plate and the sixth capacitor plate. The metal mass block and the fifth capacitor plate form a fifth capacitor and the sixth capacitor plate form a sixth capacitor. The initial capacitance values of the fifth capacitor and the sixth capacitor are equal.
[0021] The seventh capacitor board;
[0022] The eighth capacitor plate, the seventh capacitor plate and the eighth capacitor plate are disposed inside the square frame and are disposed opposite to each other in the second direction, the fifth capacitor plate and the seventh capacitor plate are spaced apart and arranged side by side in the vertical direction, and the sixth capacitor plate and the eighth capacitor plate are spaced apart and arranged side by side in the vertical direction.
[0023] The metal mass block is located between the seventh capacitor plate and the eighth capacitor plate. The metal mass block forms a seventh capacitor with the seventh capacitor plate and an eighth capacitor with the eighth capacitor plate. The initial capacitance values of the seventh capacitor and the eighth capacitor are equal.
[0024] The processor is electrically connected to the fifth capacitor plate, the sixth capacitor plate, the seventh capacitor plate, and the eighth capacitor plate, respectively. The processor is used to obtain the displacement of the metal mass block in the second direction and the rotation in the first direction based on the initial capacitance and capacitance change of the fifth and sixth capacitors, as well as the initial capacitance and capacitance change of the seventh and eighth capacitors.
[0025] Optionally, the distance between the metal mass block and each capacitor plate is equal;
[0026] The processor is based on the following formula: the displacement of the metal mass block in the first direction and the amount of rotation in the second direction:
[0027]
[0028] |C1-C2|=2ΔC1
[0029]
[0030] |C3-C4|=2ΔC2
[0031]
[0032] Δd1=x u ;
[0033] Δd2=x l ;
[0034] Wherein, C0 is the initial capacitance of the first capacitor, the second capacitor, the third capacitor, and the fourth capacitor;
[0035] d0 is the initial spacing between the first capacitor plate, the second capacitor plate, the third capacitor plate, and the fourth capacitor plate and the metal mass block;
[0036] C1 is the capacitance value of the first capacitor after the metal mass block moves;
[0037] C2 is the capacitance value of the second capacitor after the metal mass block moves;
[0038] C3 is the capacitance value of the third capacitor after the metal mass block moves;
[0039] C4 is the capacitance value of the fourth capacitor after the metal mass block moves;
[0040] Δd1 is the integral of the distance change of the metal mass block in the first direction within the size range corresponding to the first capacitor plate in the vertical direction;
[0041] Δd2 is the integral of the distance change of the metal mass block in the first direction within the size range corresponding to the third capacitor plate in the vertical direction;
[0042] U S1 The voltage values detected by the processor for the first and second capacitors;
[0043] U S2 The voltage values detected by the processor for the third and fourth capacitors;
[0044] U M This refers to the power supply voltage.
[0045] x g Let be the displacement of the metal mass block in the first direction;
[0046] θ yg This represents the amount of rotation of the metal mass block in the second direction;
[0047] M tot The transfer matrix is known.
[0048] Optionally, it also includes magnetic components disposed on the base plate, wherein in the vertical direction, the projection of the metal mass block is located between two adjacent magnetic components;
[0049] M tot =M tot (k el ,l b ,γ 11 ,γ 12 ,γ 21 ,γ 22 )
[0050] Where, k el This is the equivalent stiffness coefficient;
[0051] l b Given the bending length;
[0052] γ 11 The damping coefficient is known.
[0053] γ 12 The damping coefficient is known.
[0054] γ 21 The damping coefficient is known.
[0055] γ 22 The damping coefficient is known.
[0056] Optionally, a transmission circuit is also included, wherein the transmission circuit is disposed between each group of differential capacitors and the processor, the transmission circuit being used to convert the capacitance signal of the differential capacitor into a voltage signal, and the processor acquiring the voltage signal as a voltage value detected for the first capacitor and the second capacitor, or a voltage value detected for the third capacitor and the fourth capacitor.
[0057] Optionally, the transmission circuit includes a transformer, an amplifier, a filter, and a demodulator. The two ends of the transformer are connected to the first capacitor and the second capacitor, respectively. The amplifier is connected to the other side of the transformer. The filter is connected to the amplifier. The demodulator is connected to the filter and the processor.
[0058] Optionally, it may also include multiple leveling screws, each of which is threadedly connected to the base plate.
[0059] Optionally, it also includes a fixed base and multiple isolation covers. The square frame is fixedly connected to the fixed base, and each layer of the isolation cover covers the square frame and is fixedly connected to the fixed base. The multiple isolation covers are arranged at intervals from the inside out.
[0060] Optionally, the base plate and the square frame are movably connected in the first direction and the second direction, respectively;
[0061] The seismograph also includes a first operating element and a second operating element. The movement of the first operating element drives the base plate to move relative to the square frame in a first direction, and the movement of the second operating element drives the base plate to move relative to the square frame in a second direction.
[0062] The technical solutions provided by the embodiments of this disclosure may include the following beneficial effects:
[0063] As can be seen from the above embodiments, in the technical solution of this disclosure, the first capacitor plate and the second capacitor plate are respectively used with the metal mass block to construct the first capacitor and the second capacitor, which is conducive to constructing a differential capacitance sensor, thereby reducing electronic noise, improving measurement accuracy, and exhibiting extremely low noise effect near 1Hz, which reflects the excellent sensitivity of the differential capacitance sensor to low frequency signals, which is beneficial to the seismograph for detecting low frequency signals.
[0064] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description
[0065] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.
[0066] Figure 1 This is a schematic cross-sectional view of a seismograph according to an exemplary embodiment.
[0067] Figure 2 This is a schematic diagram of a partial cross-section of a seismograph according to an exemplary embodiment.
[0068] Figure 3 yes Figure 2 Another partial schematic diagram of the seismograph.
[0069] Figure 4 This is a partial circuit equivalent diagram of a seismograph according to an exemplary embodiment.
[0070] Figure 5 It is a background noise power spectral density curve shown in an exemplary embodiment, with a frequency range of 0.01Hz-10Hz.
[0071] Figure 6 This is a mechanical model of a seismograph according to an exemplary embodiment.
[0072] Figure 7 These are theoretical and measured curves of a transfer function illustrated according to an exemplary embodiment. Detailed Implementation
[0073] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.
[0074] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.
[0075] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."
[0076] Figure 1 This is a schematic cross-sectional view of a seismograph according to an exemplary embodiment. Figure 2 This is a partial cross-sectional schematic diagram of a seismograph according to an exemplary embodiment. Figure 3 yes Figure 2 Another partial schematic diagram of the seismograph Figure 4 This is a partial circuit equivalent diagram of a seismograph according to an exemplary embodiment. For example... Figures 1-3 As shown, the seismograph includes a square frame 1, a base plate 2, a flexible support rod 3, a first capacitor plate 4, a second capacitor plate 5, a metal mass block 6, a power supply 7, and a data acquisition card 8. The base plate 2 is located on the bottom side of the square frame 1 to seal the bottom of the frame 1. The square frame 1 can be a quartz frame. The flexible support rod 3 is fixedly connected to the base plate 2 and is located in the middle region of the square frame 1. The first capacitor plate 4 and the second capacitor plate 5 are both located inside the square frame 1, and are positioned opposite each other and spaced apart in a first direction, for example... Figure 2 As shown, the first capacitor plate 4 and the second capacitor plate 5 are in the first direction, that is... Figure 2 The projection overlap setting in the X direction.
[0077] In order to compensate for the height defects of the placement surface, the seismograph does not include multiple leveling screws. Each leveling screw passes through the base plate 2 and is threadedly connected to the base plate 2. In this way, the height defects of the placement surface can be compensated by the positional differences between the multiple leveling screws and the base plate 2, ensuring that the base plate 2 is set horizontally and improving the accuracy of the seismograph.
[0078] A metal mass block 6 is connected to the end of the flexible support rod 3 facing away from the base plate 2. This metal mass block 6 can be an aluminum alloy cube measuring 88mm × 88mm × 80mm, with a mass of approximately 1.67kg. The flexible support rod 3 can be an aluminum alloy flexible rod with a length of approximately 65mm and a radius of approximately 1.2mm. The flexible support rod 3 and the metal mass block 6 form an inverted pendulum structure, achieving a low resonant frequency and improving low-frequency sensitivity. Furthermore, the metal mass block 6 is located between the first capacitor plate 4 and the second capacitor plate 5. The power supply 7 is electrically connected to the metal mass block 6, thus enabling the construction of a first capacitor using the first capacitor plate 4 and the metal mass block 6, and a second capacitor using the second capacitor plate 5 and the metal mass block 6. The initial capacitance values of the first and second capacitors are equal, meaning the distance between the first capacitor plate 4 and the metal mass block 6 is equal to the distance between the second capacitor plate 5 and the metal mass block 6. Of course, allowable errors due to processing and assembly can be ignored. The processor is electrically connected to the first capacitor plate 4 and the second capacitor plate 5 respectively. The processor can be used to obtain the displacement of the metal mass block 6 in the first direction based on the initial capacitance of the first capacitor and the second capacitor and the amount of capacitance change.
[0079] For example, such as Figure 4 As shown, a differential capacitance induction bridge can be constructed using the first and second capacitors. After the metal mass block 6 moves, the following condition is met:
[0080]
[0081] |C1-C2|=2ΔC1;
[0082]
[0083] Where C1 is the capacitance value of the first capacitor after the metal mass block moves;
[0084] C2 is the capacitance value of the second capacitor after the metal mass block moves;
[0085] C0 is the initial capacitance of the first capacitor and the second capacitor;
[0086] d0 is the initial interval between the first capacitor plate, the second capacitor plate and the metal mass block;
[0087] Δd1 is the integral of the distance change of the metal mass block in the first direction within the size range corresponding to the first capacitor plate and the second capacitor plate in the vertical direction;
[0088] U S1 The voltage values detected by the processor for the first and second capacitors;
[0089] U M This refers to the power supply voltage.
[0090] Therefore, based on the above formula, Δd1 can be calculated, and thus the displacement of the metal mass block 6 in the first direction can be obtained.
[0091] Moreover, such as Figure 5 The image shows the power spectral density curves of the background noise in the frequency range of 0.01Hz-10Hz, where the blue curve represents the actual measured local noise and the red dashed line represents the fitted model. According to... Figure 5 It is known that the noise floor within this frequency range is below 10 pm / sqrt(Hz), compared to the noise levels of traditional capacitive displacement sensors, which are in the hundreds of pm / sqrt(Hz). This solution achieves higher accuracy and lower noise by constructing a differential capacitor. Therefore, in this disclosed technical solution, a first capacitor plate 4 and a second capacitor plate 5 are respectively used with a metal mass block 6 to construct the first and second capacitors, facilitating the construction of a differential capacitance sensor. This reduces electronic noise, improves measurement accuracy, and exhibits extremely low noise near 1Hz, demonstrating the excellent sensitivity of this differential capacitance sensor to low-frequency signals, which is beneficial for the detection of low-frequency signals by seismographs.
[0092] Furthermore, the seismograph also includes a third capacitor plate 9 and a fourth capacitor plate 10. The first capacitor plate 4 and the third capacitor plate 9 are arranged vertically at intervals and side by side. The third capacitor plate 9 and the fourth capacitor plate 10 are both located inside the square frame 1 and are arranged at intervals and opposite to each other on the second square, as shown below. Figure 3 As shown, the third capacitor plate 9 and the fourth capacitor plate 10 are arranged opposite each other in the Y direction, and the fourth capacitor plate 10 and the second capacitor plate 5 are arranged side by side and spaced apart in the vertical direction. The vertical direction is parallel to the length direction of the flexible support rod, and the vertical direction, the first direction and the second direction are arranged perpendicular to each other.
[0093] Metal mass block 6 is located between the third capacitor plate 9 and the fourth capacitor plate 10. Metal mass block 6 and the third capacitor plate 9 form the third capacitor, and metal mass block 6 and the fourth capacitor plate 10 form the fourth capacitor. The initial capacitance values of the third and fourth capacitors are equal, meaning the distance between the third capacitor plate 9 and the metal mass block 6 is equal to the distance between the fourth capacitor plate 10 and the metal mass block 6. Allowable errors due to processing and assembly can be ignored. The initial capacitance values of the third capacitor and the first capacitor are equal. Data acquisition card 8 is electrically connected to the third capacitor plate 9 and the fourth capacitor plate 10 respectively. This data acquisition card 8 can be used to obtain the displacement of metal mass block 6 in a first direction and the rotation in a second direction based on the initial capacitance and capacitance change of the first and second capacitors, respectively. The second direction is perpendicular to both the first and vertical directions.
[0094] For example, referring to the formula above, we can obtain:
[0095]
[0096] |C3-C4|=2ΔC2
[0097]
[0098] Where C3 is the capacitance value of the third capacitor after the metal mass block moves;
[0099] C4 is the capacitance value of the second capacitor after the metal mass block moves;
[0100] C0 is the initial capacitance of the third and fourth capacitors;
[0101] d0 is the initial interval between the third capacitor plate 9 and the fourth capacitor plate 10 and the metal mass block 6.
[0102] Δd2 is the integral of the distance change of the metal mass block 6 in the first direction within the size range corresponding to the third capacitor plate 9 and the fourth capacitor plate 10 in the vertical direction;
[0103] U S1 The voltage values detected by the processor for the third and fourth capacitors;
[0104] U M This is the power supply voltage.
[0105] Furthermore:
[0106]
[0107] Δd1=x u
[0108] Δd2=x l
[0109] Where, x g The displacement of the metal mass block in the first direction, i.e. Figure 3 Displacement in the X direction;
[0110] θ yg The rotation of the metal mass block in the second direction, i.e. Figure 3 The amount of rotation about the Y-axis;
[0111] M tot [1,1] and M tot [2,1] describes the transmission relationship between the actual displacement in the first direction and the reading parameters of the first and second capacitors;
[0112] M tot [2,1]M tot [2,2] describes the relationship between the amount of rotation in the second direction and the reading parameters of the first and second capacitors.
[0113] Based on the known transfer matrix, the displacement changes detected by the first and second capacitors, as well as the displacement changes detected by the third and fourth capacitors, are decoupled. This allows us to obtain the displacement of the metal mass block 6 in the first direction and the rotation in the second direction. Thus, the motion in the rotational degree of freedom can be measured using a seismograph, which expands the application scope compared to seismographs in related technologies that can only measure the translational degree of freedom.
[0114] Regarding the known transfer matrix M tot The results can be obtained by calculation based on the dynamic model of the flexible support rod 3 and the metal mass block 6.
[0115] In some examples, the seismograph may also include magnetic components mounted on the base plate 2, with the projection of the metal mass 6 located between two adjacent magnetic components in the vertical direction. For instance, the seismograph may include four magnetic components, with two opposite each other along the X-direction and two opposite each other along the Y-direction, and the projection of the metal mass 6 located between any pair of magnetic components in the vertical direction. Thus, when the metal mass 6 moves, it cuts the magnetic field constructed by each pair of magnetic components, utilizing the eddy current effect to achieve system damping, which helps reduce detection noise and improve detection sensitivity.
[0116] Furthermore, the known transfer matrix satisfies:
[0117] M tot =M tot (k el ,l b ,γ 11 ,γ 12 ,γ 21 ,γ 22 )
[0118] in,
[0119] k el Given the effective stiffness of the flexible support rod;
[0120] l b Given the bending length;
[0121] γ 11 The damping coefficient is known.
[0122] γ 12 The damping coefficient is known.
[0123] γ 21 The damping coefficient is known.
[0124] γ 22 The damping coefficient is known.
[0125] The values are shown in the table below:
[0126]
[0127] For this functional relationship, we can take an example based on... Figure 6 The mechanical model is used to establish the dynamic model, and the geometric relationship can be expressed as follows:
[0128]
[0129] in,
[0130] h0 represents the distance between the bottom of the flexible support rod and the platform;
[0131] L represents the length of the curved section;
[0132] l b This indicates the distance between the two bending points and the upper and lower ends of the flexible support rod;
[0133] α and β are the bending angles;
[0134] x tm This represents the displacement of the metal mass block 6;
[0135] θ tm The tilt angle of the metal mass block 6;
[0136] h cm This indicates the distance between the center of mass of the metal mass block 6 and the bottom of the flexible support rod 3;
[0137] x g Displacement representing ground motion;
[0138] θ yg It indicates the angle of the ground tilting motion.
[0139] Due to α, β and θ yg Since it is much smaller than 1, the following approximation can be obtained:
[0140]
[0141] Write gravitational potential energy as x tm θ tm x g and θ yg The function, expanded into a second-order approximation, yields:
[0142]
[0143] The equivalent stiffness coefficients at the other two bending points are k el Elasticity can be expressed as:
[0144]
[0145] Given a mass M and a moment of inertia I about the y-axis (second direction), the kinetic energy can be expressed as:
[0146]
[0147] The Lagrange can be written as:
[0148] L = TV k -V g
[0149] According to Lagrange's equations, the force and torque can be obtained as follows:
[0150]
[0151] Constructing the matrix:
[0152]
[0153] Furthermore:
[0154] x u =x tm -x g -h u θ yg +(h u -h cm -h0)θ tm
[0155] x l =x tm -x g -h l θ yg +(hl-h cm -h0)θ tm
[0156] Define two matrices to express mathematical relationships:
[0157]
[0158] The eddy current damping generated by the magnetic components added to the base plate 2 can be represented by the following damping matrix:
[0159]
[0160] The air damping and eddy current damping are directly related to the relative motion of the metal mass block 6, and can be expressed by the following relationship to obtain the damping matrix:
[0161]
[0162] Furthermore:
[0163] M At =M A -iΩM γ M Cγ M Bt =M B -iΩM γ M Dγ
[0164] The transfer matrix can be represented as:
[0165] M tot =M C [M I -M At ] -1 M Bt +MD
[0166]
[0167] Where Ω is the angular frequency.
[0168] Furthermore, Figure 7 M is shown in tot [1,1]、M tot [2,1]、M tot [1,2] and M tot The theoretical curve of the transfer function [2,2] and M tot [1,1] and M tot [1,2] The measurement curves of the transfer function. The solid line represents M. tot [1,1] and M tot The measurement curve of the transfer function [2,1] is shown in the image. Figure 7 It can be seen that M tot [1,1] and M tot The measured curve of [2,1] shows extremely high agreement with the theoretical curve. However, given the current low sensitivity of laboratory tiltmeters, there is no M... tot [2,1] and M tot The measurement curve of the transfer function [2,2], but based on M tot [1,1] and M tot The minimal error between the theoretical and measured curves of [2,1] can also, to some extent, infer M. tot [2,1] and M tot The theoretical and measured curves of [2,2] show very small errors.
[0169] At the same time, based on Figure 7 The curves shown indicate that resonance occurs at two peaks, approximately 0.86 Hz and 3.75 Hz. The low resonance frequencies demonstrate the excellent sensitivity of the seismograph in this disclosure to low-frequency signals, which is helpful for detecting low-frequency seismic signals. At the same time, it can be seen that the seismograph in this disclosure has a synchronous response to translational and rotational degrees of freedom, realizing the measurement and decoupling of translation and rotation, thus making up for the current technical deficiencies in this regard.
[0170] Based on the above embodiments, the seismograph may further include a fifth capacitor plate 11, a sixth capacitor plate 12, a seventh capacitor plate 13, and an eighth capacitor plate 14. The fifth capacitor plate 11 and the sixth capacitor plate 12 are disposed inside the square frame 1 and are disposed opposite to each other in the second direction. The metal mass block 6 is located between the fifth capacitor plate 11 and the sixth capacitor plate 12. The metal mass block 6 forms a fifth capacitor with the fifth capacitor plate 11 and a sixth capacitor with the sixth capacitor plate 12. The initial capacitance values of the fifth capacitor and the sixth capacitor are equal.
[0171] The seventh capacitor plate 13 and the eighth capacitor plate 14 are disposed inside the square frame 1 and are disposed opposite each other in the second direction. The fifth capacitor plate 11 and the seventh capacitor plate 13 are disposed side by side with a gap in the vertical direction. The sixth capacitor plate 12 and the eighth capacitor plate 14 are disposed side by side with a gap in the vertical direction. The metal mass block 6 is located between the seventh capacitor plate 13 and the eighth capacitor plate 14. The metal mass block 6 and the seventh capacitor plate 13 form the seventh capacitor and the metal mass block 6 and the eighth capacitor plate 14 form the eighth capacitor. The initial capacitance values of the seventh capacitor and the eighth capacitor are equal.
[0172] The data acquisition card 8 is electrically connected to the fifth capacitor plate 11, the sixth capacitor plate 12, the seventh capacitor plate 13, and the eighth capacitor plate 14, respectively. The data acquisition card 8 is used to acquire the displacement of the metal mass block 6 in the second direction and the rotation in the first direction based on the initial capacitance and capacitance change of the fifth and sixth capacitors, as well as the initial capacitance and capacitance change of the seventh and eighth capacitors. For specific implementation details, please refer to the aforementioned embodiments. In this way, the motion of the metal mass block 6 in four degrees of freedom—movement and rotation in the first direction and movement and rotation in the second direction—can be measured. For specific implementation details, please refer to the implementation methods of the first and second capacitors; these will not be elaborated upon here.
[0173] Based on the above embodiments, such as Figure 4 As shown, the seismograph may also include a transmission circuit, and this transmission circuit is provided between each group of differential capacitors and the acquisition card 8. This transmission circuit can be used to convert the capacitance signals of the differential capacitors into voltage signals. The processor acquires the voltage signals as the voltage values detected for the first and second capacitors, or the voltage values detected for the third and fourth capacitors, thereby calculating Δ. d1 , and Δ d2 .
[0174] Taking the transmission circuit between the first capacitor and the second capacitor as an example, let's continue with... Figure 4 As shown, the transmission circuit includes a transformer, an amplifier G, a filter BP, and a demodulator. The transformer is connected to a differential capacitor formed by a first capacitor and a second capacitor. The front end of the differential capacitor is connected to a power supply 7 via the filter BP. The first capacitor and the second capacitor are connected... Figure 4 Amplifier G is connected to the other side of the transformer, filter BP is connected to amplifier G, and demodulators (including AD630 and LP) are connected to filter BP and acquisition card 8. The transformer transmits the unbalanced voltage transmitted by the differential capacitance sensor to the filter for filtering. After filtering, it enters the lock-in amplifier, and then passes through a second-order low-pass filter to transmit the low-frequency components generated by the movement of the metal mass block 6 to acquisition card 8.
[0175] The seismograph also includes a fixed base 15 (a platform placed on the bottom surface) and a multi-layered isolation enclosure 16, such as Figure 1 The diagram shows a three-layer isolation enclosure 16. A square frame 1 is fixedly connected to a fixed base 15. Each layer of the isolation enclosure 16 covers the square frame 1 and is fixedly connected to the fixed base 15. The multiple layers of isolation enclosures 16 are arranged alternately from the inside out. In this way, the multiple layers of isolation enclosures 16 help to achieve sound insulation and heat insulation within the square frame 1, reduce the impact of external atmospheric pressure disturbances, and reduce the impact of external environmental factors on the seismograph detection.
[0176] In the above embodiments, the base plate 2 and the square frame 1 are movably connected to the first square and the second square, respectively. The seismograph also includes a first operating member and a second operating member. The movement of the first operating member drives the base plate 2 to move relative to the square frame 1 in a first direction, thereby adjusting the distance between the first capacitor plate 4, the second capacitor plate 5, the third capacitor plate 9, and the fourth capacitor plate 10 and the metal mass block 6. This helps to compensate for assembly or processing errors, so that the capacitance values of the first capacitor, the second capacitor, the third capacitor, and the fourth capacitor are equal in the initial stage. Similarly, the movement of the second operating member drives the base plate 2 to move relative to the square frame 1 in a second direction, thereby adjusting the distance between the fifth capacitor plate 11, the sixth capacitor plate 12, the seventh capacitor plate 13, and the eighth capacitor plate 14 and the metal mass block 6. This helps to compensate for assembly or processing errors, so that the capacitance values of the fifth capacitor, the sixth capacitor, the seventh capacitor, and the eighth capacitor are equal in the initial stage.
[0177] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.
[0178] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.
Claims
1. A seismograph based on an inverted pendulum structure and a capacitive displacement sensor, characterized in that, include: Square frame; A base plate, which is disposed on the bottom side of the square frame; A flexible support rod, which is connected to the base plate and located within the square frame; First capacitor plate; The second capacitor plate, the first capacitor plate and the second capacitor plate are disposed inside the square frame and are disposed opposite to each other in a first direction; A metal mass block is connected to one end of the flexible support rod away from the base plate, and the metal mass block is located between the first capacitor plate and the second capacitor plate. The metal mass block and the first capacitor plate form a first capacitor, and the metal mass block and the second capacitor plate form a second capacitor. The initial capacitance values of the first capacitor and the second capacitor are equal. A power source, which is electrically connected to the metal mass block; The processor is electrically connected to the first capacitor plate and the second capacitor plate respectively, and the processor is used to obtain the displacement of the metal mass block in a first direction based on the initial capacitance and capacitance change of the first capacitor and the second capacitor.
2. The seismograph according to claim 1, characterized in that, Also includes: The third capacitor plate, the first capacitor plate and the third capacitor plate are arranged side by side with a gap in the vertical direction; The fourth capacitor plate, the third capacitor plate and the fourth capacitor plate are disposed inside the square frame and are disposed opposite to each other in the second direction. The second capacitor plate and the fourth capacitor plate are spaced apart and arranged side by side in the vertical direction, and the vertical direction is parallel to the length direction of the flexible support rod. The metal mass block is located between the third capacitor plate and the fourth capacitor plate. The metal mass block forms a third capacitor with the third capacitor plate and a fourth capacitor with the fourth capacitor plate. The initial capacitance values of the third capacitor and the fourth capacitor are equal. The processor is electrically connected to the third capacitor plate and the fourth capacitor plate respectively. The processor is used to obtain the displacement of the metal mass block in a first direction and the rotation in a second direction based on the initial capacitance and capacitance change of the first capacitor and the second capacitor, and the initial capacitance and capacitance change of the first capacitor and the second capacitor, wherein the second direction, the first direction and the vertical direction are perpendicular to each other.
3. The seismograph according to claim 2, characterized in that, Also includes: Fifth capacitor board; The sixth capacitor plate, the fifth capacitor plate and the sixth capacitor plate are disposed inside the square frame and are disposed opposite to each other in the second direction. The metal mass block is located between the fifth capacitor plate and the sixth capacitor plate. The metal mass block and the fifth capacitor plate form a fifth capacitor and the sixth capacitor plate form a sixth capacitor. The initial capacitance values of the fifth capacitor and the sixth capacitor are equal. The seventh capacitor board; The eighth capacitor plate, the seventh capacitor plate and the eighth capacitor plate are disposed inside the square frame and are disposed opposite to each other in the second direction, the fifth capacitor plate and the seventh capacitor plate are spaced apart and arranged side by side in the vertical direction, and the sixth capacitor plate and the eighth capacitor plate are spaced apart and arranged side by side in the vertical direction. The metal mass block is located between the seventh capacitor plate and the eighth capacitor plate. The metal mass block forms a seventh capacitor with the seventh capacitor plate and an eighth capacitor with the eighth capacitor plate. The initial capacitance values of the seventh capacitor and the eighth capacitor are equal. The processor is electrically connected to the fifth capacitor plate, the sixth capacitor plate, the seventh capacitor plate, and the eighth capacitor plate, respectively. The processor is used to obtain the displacement of the metal mass block in the second direction and the rotation in the first direction based on the initial capacitance and capacitance change of the fifth and sixth capacitors, as well as the initial capacitance and capacitance change of the seventh and eighth capacitors.
4. The seismograph according to claim 2, characterized in that, It also includes magnetic components disposed on the base plate, wherein in the vertical direction, the projection of the metal mass block is located between two adjacent magnetic components; in, This is the equivalent stiffness coefficient; Given the bending length; The damping coefficient is known. The damping coefficient is known. The damping coefficient is known. The damping coefficient is known.
5. The seismograph according to claim 3, characterized in that, It also includes a transmission circuit, which is disposed between each group of differential capacitors and the processor. The transmission circuit is used to convert the capacitance signal of the differential capacitor into a voltage signal. The processor acquires the voltage signal as a voltage value detected for the first capacitor and the second capacitor, or a voltage value detected for the third capacitor and the fourth capacitor.
6. The seismograph according to claim 5, characterized in that, The transmission circuit includes a transformer, an amplifier, a filter, and a demodulator. The two ends of the transformer are connected to the first capacitor and the second capacitor, respectively. The amplifier is connected to the other side of the transformer. The filter is connected to the amplifier. The demodulator is connected to the filter and the processor.
7. The seismograph according to claim 1, characterized in that, It also includes multiple leveling screws, each of which is threadedly connected to the base plate.
8. The seismograph according to claim 1, characterized in that, It also includes a fixed base and multiple isolation covers. The square frame is fixedly connected to the fixed base, and each layer of the isolation cover covers the square frame and is fixedly connected to the fixed base. The multiple isolation covers are arranged at intervals from the inside out.
9. The seismograph according to claim 1, characterized in that, The base plate and the square frame are movably connected in a first direction and a second direction, respectively. The seismograph also includes a first operating element and a second operating element. The movement of the first operating element drives the base plate to move relative to the square frame in a first direction, and the movement of the second operating element drives the base plate to move relative to the square frame in a second direction.