A magnetic-static hybrid suspension accelerometer and its measurement method

Abstract

The present invention discloses an anti-magnetic electrostatic hybrid suspension accelerometer and a measurement method thereof. The accelerometer includes a support frame, a permanent magnet array, a suspension element, a non-magnetic metal sheet, a driving electrode, a photoelectric displacement sensor, a driving electrode controller, and a high-voltage amplifier; the non-magnetic metal sheet is glued to both ends of the suspension element; the suspension element is located at the center of the groove of the permanent magnet array; the driving electrode is placed directly opposite the non-magnetic metal sheet, adopts a differential structure, and the photoelectric displacement sensor is arranged at both ends of the suspension element; the non-magnetic metal sheet is controlled by the voltage in the driving electrode to induce an electrostatic force, and the position of the non-magnetic metal sheet is controlled by the resultant force to change until the non-magnetic metal sheet stabilizes at a preset position, thereby achieving stable suspension in the direction of the measuring axis. The steps of the measurement method include: carrying out the installation of the accelerometer; carrying out the debugging of the accelerometer; and carrying out the actual test of the accelerometer. The present invention realizes high-precision measurement of tiny accelerations.

Description

Technical Field

[0001] The present invention relates to the field of precision instruments and meters, and in particular to an anti-magnetic electrostatic hybrid suspension accelerometer and a measurement method thereof. Background Art

[0002] As one of the core measurement components of inertial systems, accelerometers are widely used in fields such as inertial navigation, planetary geophysics, and space experiments. These applications include gravity field measurements, seismic wave detection, topography and landform changes, drag-free spacecraft control, and guided missile strikes. With the increasing number of planetary physics missions exploring Earth and outer space, the development of advanced accelerometers is of great significance. This is especially true for gravity field measurements, topography and landform changes, and other research exploring the inner and outer structure, physical processes, and evolutionary history of Earth and other planets. The measurement accuracy of accelerometers directly impacts the accuracy of these planetary physics experiments. Currently, various high-precision accelerometers are being developed, and they are a hot topic in future fundamental planetary physics research.

[0003] An accelerometer typically consists of a stator, a sensitive element, a conversion element, and a conversion circuit. It measures the acceleration of the object by measuring the relative motion between the sensitive element and the stator as the stator moves with the object being measured and converting this motion into an electrical signal. Traditional accelerometers, including quartz flexure accelerometers, fiber optic accelerometers, and silicon micromachined accelerometers, suffer from unavoidable friction between the sensitive element and the stator, hindering further improvements in measurement accuracy. Suspended accelerometers, by suspending the inertial element, theoretically offer the highest accuracy.

[0004] Current suspension accelerometers primarily include electrostatic, magnetic, and superconducting suspension accelerometers. Electrostatic and magnetic suspension accelerometers utilize fully active suspension, offering high precision and a wide range. However, they suffer from severe vibration coupling between degrees of freedom, significantly impacting key performance indicators such as the accelerometer's measurement system stability, response speed, and accuracy. They also place high demands on the control of sensitive components. Superconducting suspension accelerometers achieve passive, stable suspension, minimizing the impact of vibration coupling between degrees of freedom and resulting in higher measurement accuracy. However, they impose strict requirements on ambient temperature and possess a complex structure.

[0005] Compared to the aforementioned methods, diamagnetic levitation utilizes the diamagnetic effect of materials to achieve passive, frictionless, and statically stable suspension at room temperature. Its simple structure and high sensitivity to stator vibrations make it highly promising for high-precision and ultra-high-precision acceleration measurement due to its low stiffness and self-stabilizing suspension. However, the limited diamagnetic force severely restricts the expansion of its measurement range.

[0006] Prior to this invention, in terms of the measurement of tiny vibration signals, most domestic research focused on single electrostatic suspension measurement and passive anti-magnetic suspension measurement. There has not been any invention related to a hybrid suspension accelerometer based on the combination of anti-magnetic suspension principle and electrostatic suspension principle similar to this patent. Summary of the Invention

[0007] In order to address the deficiencies of the prior art, the present invention discloses an anti-magnetic electrostatic hybrid suspension accelerometer and a measurement method thereof; the measurement accuracy and measurement range of tiny vibration signals can be improved, meeting the physical measurement requirements of high-precision and ultra-high-precision instruments.

[0008] The technical solution for implementing the present invention is:

[0009] A diamagnetic electrostatic hybrid suspension accelerometer, comprising: a support frame, a permanent magnet array, a suspension element, a non-magnetic metal sheet, a drive electrode, a photoelectric displacement sensor, a drive electrode controller, and a high-voltage amplifier; the permanent magnet array is a groove-type permanent magnet array composed of three groups of single pairs of permanent magnet arrays with exactly the same shape and magnetization, each group of single pairs of permanent magnet arrays consisting of two axially magnetized rectangular permanent magnets of the same size, opposite magnetization directions, and equal size; the suspension element and the non-magnetic metal sheet are assembled together by glue; the suspension element is made of three rectangular pieces made of diamagnetic material. The non-magnetic metal sheet is a rectangular sheet with a length larger than the distance between the two side plates, which connects the side plates of the suspension element together; the suspension element is located inside the groove of the permanent magnet array, and the permanent magnet array generates a force that hinders the relative motion of the suspension element in the non-measurement axis direction, thereby realizing passive stable suspension of the suspension element and the non-magnetic metal sheet in the non-measurement axis direction; the driving electrode is placed opposite to the non-magnetic metal sheet, and the driving electrode adopts a differential structure, that is, two sets of driving electrodes are placed at both ends of the inertial element, symmetrically distributed, and when the driving electrodes are energized, they both exert force on the suspension element in the middle. Generates attractive force; photoelectric displacement sensors are located at both ends of the suspension element to measure its position signal. The photoelectric displacement sensors convert the collected position signal of the suspension element into electrical signals in real time and transmit them to the drive electrode controller. The drive electrode controller generates a control variable based on the difference between the electrical signal measured by the photoelectric displacement sensor and a preset electrical signal to reduce the difference to zero. This control variable is input into the drive electrodes. The preset position electrical signal is the electrical signal set when the suspension element is located at the center of the two sets of drive electrodes when the permanent magnet array is not subjected to external vibration. A high-voltage amplifier amplifies the control voltage, generating two output signals with a difference of twice the control variable. These signals are then input into the front and rear sets of drive electrodes. The control voltage in the drive electrodes induces an electrostatic force on the non-magnetic metal sheet. The forces exerted on the non-magnetic metal sheet by the two sets of drive electrodes are in opposite directions, and the net force acting on the non-magnetic metal sheet is the difference between the two forces. This causes the position of the suspension element and the non-magnetic metal sheet to change until the non-magnetic metal sheet achieves active and stable suspension along the measurement axis at the preset position. The hybrid suspension accelerometer is completely sealed.

[0010] Furthermore, the permanent magnet array pole arrangement adopts an axially magnetized permanent magnet array with a mixed arrangement of "Opposite" and "Halbach". Each single pair of "Opposite" arrays is composed of two axially magnetized rectangular permanent magnets of the same size, opposite magnetization strength directions and equal size, and are arranged according to the "Halbach" array at the combination position of the single pair of "Opposite" permanent magnet arrays.

[0011] Furthermore, the suspension element and the non-magnetic metal sheet are assembled together by glue. The suspension element is made of three rectangular thin sheets made of anti-magnetic material. The rectangular thin sheets have the same width. One of them is longer and serves as the bottom plate of the suspension element. The other two pieces of equal length constitute the side plates of the suspension element. The non-magnetic metal sheet is a rectangular thin sheet, and its length is larger than the distance between the two side plates. The side plates are connected together to make the overall structure compact and firm.

[0012] Furthermore, the ratio of the sum of the volumes of the side plates and the non-magnetic metal sheets of the suspension element to the volume of the bottom plate of the suspension element is less than 3:2 when thin sheets of the same thickness are selected.

[0013] A measurement method for a diamagnetic electrostatic hybrid suspension accelerometer specifically includes the following three steps:

[0014] Step S1: Installing the anti-magnetic electrostatic hybrid suspension accelerometer. First, symmetrically install the driving electrodes on the support frame, place the suspension element on the permanent magnet array, and use a thin rope to limit the displacement of the suspension element on the x-axis. By adjusting the position between the permanent magnet array and the suspension element, wait until the non-magnetic metal sheet is facing the driving electrodes. Adjust the position of the photoelectric displacement sensor so that its emitted laser is aligned with the bottom plate of the anti-magnetic suspension element, and ensure that the distance between the photoelectric displacement sensor and the anti-magnetic suspension element is within the linear working area of ​​the photoelectric sensor, thereby completing the installation of the anti-magnetic electrostatic hybrid suspension accelerometer.

[0015] Step S2, debugging the anti-magnetic electrostatic hybrid suspension accelerometer; by adjusting the exciter to change the magnitude and frequency of the acceleration signal, measuring and recording characteristic parameters such as the amplitude and frequency of the output voltage difference signal of the high-voltage amplifier at this time, drawing a curve of the output voltage amplitude changing with the characteristic parameters of the acceleration signal, repeating the experiment multiple times to obtain an average curve, revealing the performance parameters of the hybrid suspension accelerometer such as the measurement range, linear region, linearity, sensitivity, resolution, response time, and repetition rate, thereby completing the debugging of the anti-magnetic electrostatic hybrid suspension accelerometer.

[0016] Step S3, carry out actual testing of the anti-magnetic electrostatic hybrid suspension accelerometer; by adjusting the exciter, change and record the characteristic parameters of the actual acceleration signal, and at the same time record the characteristic parameters of the acceleration signal measured by the anti-magnetic electrostatic hybrid suspension accelerometer based on the performance parameters determined during the debugging process, compare and analyze the actual acceleration signal and the test signal, obtain measurement accuracy, and complete the actual testing of the anti-magnetic electrostatic hybrid suspension accelerometer.

[0017] Furthermore, the specific measurement principle is as follows: taking the measured object performing simple harmonic oscillation along a horizontal line as an example, the measured object drives the permanent magnet array to move, causing relative motion between the inertial element and the permanent magnet array. The anti-magnetic levitation force on the suspension element is evenly distributed along the direction of motion, so that the inertial element always has a tendency to perform horizontal linear motion relative to the permanent magnet array at a certain suspension height. After the photoelectric displacement sensor detects the position signal in real time, when the position of the non-magnetic metal sheet shifts, the drive electrode generates a corresponding control voltage, which is amplified by the high-voltage amplifier and acts on the drive electrode controller, inducing an electrostatic force to act on the non-magnetic metal sheet until it reaches the preset position.

[0018] At this time, the force balance equation between the suspension element and the non-magnetic metal sheet is:

[0019] mx=-kx r -f x x r +F d

[0020] Where m is the mass of the inertial element composed of the suspension element and the non-magnetic metal sheet, x r is the relative displacement of the inertial element relative to the permanent magnet array, x is the absolute displacement of the inertial element, F d is the electrostatic driving force, which is the x-direction component of the total electrostatic force exerted by the driving electrode on the non-magnetic metal sheet; k is the x-direction negative stiffness of the suspension element made of diamagnetic material in the permanent magnet array; f x It is the electromagnetic damping caused by motion in a magnetic field.

[0021] For the electrostatic driving force F d ,have:

[0022]

[0023] F d =-K x x+K vx V com

[0024]

[0025]

[0026] Where ε0 is the absolute dielectric constant, ε r is the relative dielectric constant, K x , K vx is the equivalent stiffness of electrostatic force, V ref is the preset voltage, V con The feedback voltage is applied to the drive controller, A is the electrode area, d is the nominal gap between the electrodes, and F dThe size is determined by the voltage applied to the driving electrode by the driving electrode controller. The relative dielectric constant is related to the distance between the non-magnetic metal sheet and the driving electrode. When the non-magnetic metal sheet is not large relative to the preset position during the vibration of the measured object, and the control voltage is small relative to the preset voltage, K x , K vx can be considered as a constant.

[0027] At this time, the measurement principle of the accelerometer is:

[0028]

[0029] Where G s (s) is the transfer function of the measurement link, G c (s) is the transfer function of the control box, G a (s) is the transfer function of the high-voltage amplifier. The acceleration signal measured by the accelerometer and the control signal from the control box exhibit the transfer function relationship shown above. During the debugging phase of the anti-magnetic electrostatic hybrid suspension accelerometer, the input and output curves of the anti-magnetic electrostatic hybrid suspension accelerometer are experimentally tested. When measuring performance parameters such as range, sensitivity, and resolution, the control voltage is the input of the anti-magnetic electrostatic hybrid suspension accelerometer, and the acceleration signal is the output of the anti-magnetic electrostatic hybrid suspension accelerometer. After debugging, when the accelerometer is used in actual applications, the determined performance parameters are used as a carrier, and the corresponding acceleration signal is output based on the voltage changes caused by the acceleration signal to be measured.

[0030] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0031] (1) The present invention realizes the function of measuring tiny vibration signals; anti-magnetic suspension overcomes the friction problem commonly existing in existing high-precision accelerometers, realizes the free response of the sensor's sensitive elements, and the low stiffness characteristic makes the sensor extremely sensitive, which has a natural advantage in measuring tiny vibration signals.

[0032] (2) The present invention can realize the measurement of severe vibration signals; the anti-magnetic electrostatic hybrid suspension accelerometer breaks through the bottleneck of the traditional anti-magnetic suspension accelerometer due to the limitation of the anti-magnetic force level, which restricts the amplitude range of the accelerometer. The proposed hybrid anti-magnetic suspension accelerometer no longer relies on anti-magnetic force to compensate for the displacement of the inertial element. The electrostatic suspension system generates controllable electrostatic force compensation to ensure the stable suspension of the inertial element under severe vibration, thereby realizing the measurement of severe vibration signals.

[0033] (3) The present invention can achieve high-precision signal measurement; the anti-magnetic electrostatic hybrid suspension accelerometer realizes passive suspension of the inertial element in the non-measurement axis direction by introducing anti-magnetic suspension technology, thereby reducing the degree of vibration coupling between the multiple degrees of freedom in the measurement axis direction, improving the key performance of the accelerometer measurement system such as stability, response speed and accuracy, and facilitating the control of sensitive elements;.

[0034] (4) The anti-magnetic levitation in the present invention is not limited by Earnshaw's theorem and does not require any energy input, that is, it can achieve room temperature, passive, frictionless, static stable suspension, greatly simplifying the structure and cost of the sensor system.

[0035] (5) The present invention is simple and easy to implement, has high reliability and strong fault tolerance, and can well achieve high-precision measurement of weak acceleration signals. It is suitable for basic planetary physics research occasions with high reliability and high performance requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the overall structure of an anti-magnetic electrostatic hybrid suspension accelerometer.

[0037] Figure 2 Schematic diagram of the mechanical system suspension of an anti-magnetic electrostatic hybrid suspension accelerometer.

[0038] Figure 3 Schematic diagram of the three-dimensional magnetic field of an axially magnetized permanent magnet array in a mixed arrangement of "Opposite" and "Halbach".

[0039] Figure 4 Schematic diagram of the overall three-dimensional anti-magnetic force between the suspension element and the non-magnetic metal sheet.

[0040] Figure 5 Schematic diagram of the force conditions and measurement principle of the suspension element and non-magnetic metal sheet.

[0041] Figure 6 Schematic diagram of the input and output curves of an anti-magnetic electrostatic hybrid suspension accelerometer.

[0042] Figure 7 A schematic diagram of the input-to-output amplitude ratio versus frequency for a diamagnetic electrostatic hybrid suspension accelerometer. The following components are labeled: support frame 1, permanent magnet array 2, suspension element made of diamagnetic material 3, non-magnetic metal sheet 4, drive electrode 5, photoelectric displacement sensor 6, drive electrode controller 7, and high-voltage amplifier 8. DETAILED DESCRIPTION

[0043] The present invention will be further explained below with reference to the accompanying drawings.

[0044] Figure 1The present invention is a schematic diagram of the overall structure of an anti-magnetic electrostatic hybrid suspension accelerometer. The hybrid suspension method is composed of an active suspension control method based on the electrostatic suspension principle and a passive suspension method based on the anti-magnetic suspension principle. The driving electrode (5) generates an electrostatic force that acts on the non-magnetic metal sheet (4) in real time to offset the vibration of the inertial element composed of the suspension element (3) and the non-magnetic metal sheet (4) in the horizontal measurement axis direction relative to the permanent magnet base under different vibrations, thereby achieving active stable suspension of the acceleration inertial element in the horizontal measurement axis direction; the permanent magnet array (2) generates an anti-magnetic force that acts on the suspension element (3), offsets the gravity on the inertial element composed of the suspension element (3) and the non-magnetic metal sheet (4), thereby achieving passive stable suspension of the acceleration inertial element in the non-measurement axis direction. The main mechanical structure of an anti-magnetic electrostatic hybrid suspension accelerometer is as follows: Figure 2 shown.

[0045] The present invention provides an anti-magnetic electrostatic hybrid suspension accelerometer, comprising a support frame (1), a permanent magnet array (2), a suspension element (3), a non-magnetic metal sheet (4), a drive electrode (5), a photoelectric displacement sensor (6), a drive electrode controller (7), and a high-voltage amplifier (8).

[0046] In mechanical structures, such as Figure 3 As shown, the permanent magnet array (2) has an "Opposite" and "Halbach" arrangement of magnetic poles, which consists of three pairs of long permanent magnets in an "Opposite" arrangement. Each "Opposite" permanent magnet array consists of two axially magnetized permanent magnets that are magnetized in opposite directions. The three groups of "Opposite" permanent magnets are arranged in a "Halbach" arrangement, and each permanent magnet is made of neodymium iron boron (NdFeB). The size of a single permanent magnet is 5mm×5mm×30mm; the suspension element (3) is made of anti-magnetic material pyrolytic graphite, with a base plate size of 4mm×20mm×0.5mm and a side plate size of 4mm×10mm×0.5mm; the non-magnetic metal sheet (4) is made of non-magnetic metal aluminum, with a size of 4mm×2mm×0.5mm.

[0047] like Figure 4 As shown, within the bottom plate suspension plane of the suspension element (3), the permanent magnet array (2) can spontaneously generate a sawtooth magnetic field in the y direction, a uniform magnetic field that slowly decays from the center line to both sides in the x direction, and a rapidly decaying magnetic field along the z direction. The suspension element (3) excites position-dependent magnetic potential energy in the steady-state magnetic field generated by the permanent magnet array (2). Figure 5As shown, the total potential energy (composed of the magnetic potential energy and the gravitational potential energy) of the suspension element (3) and the non-magnetic metal sheet (4) has a minimum point along the z-axis direction. According to the principle of minimum potential energy, the suspension element (3) and the non-magnetic metal sheet (4) can be passively and stably suspended at the minimum point of the total potential energy, that is, the anti-magnetic force is equal to the gravity of the suspension element (3) and the non-magnetic metal sheet (4), thereby ensuring the realization of the stable suspension function of the anti-magnetic electrostatic hybrid suspension accelerometer in the z-axis direction. At the same time, the distribution of the magnetic potential energy along the y-axis direction ensures that the suspension element (3) and the non-magnetic metal sheet (4) can achieve passive stable suspension at the center position of the permanent magnet array (2) in the y-axis direction. However, there is no minimum point in the total potential energy in the x-direction. The anti-magnetic electrostatic hybrid suspension accelerometer cannot achieve passive stable suspension using the anti-magnetic suspension principle. It is necessary to introduce active electrostatic suspension through the non-magnetic metal sheet (4) to achieve the suspension function of the anti-magnetic electrostatic hybrid suspension accelerometer, avoid the negative impact caused by friction, and ensure the free response of the inertial element of the accelerometer.

[0048] The suspension element (3) is located inside the groove of the permanent magnet array (2). The permanent magnet array (2) generates a force that hinders relative motion on the suspension element (3) in the non-measurement axis direction, thereby realizing passive stable suspension of the suspension element (3) and the non-magnetic metal sheet (4) in the non-measurement axis direction. The driving electrode (5) is placed opposite to the non-magnetic metal sheet (4). The driving electrode (5) adopts a differential structure, that is, two groups of driving electrodes (5) are respectively placed at both ends of the inertial element and are symmetrically distributed. When the driving electrodes (5) are energized, they both generate an attractive force on the middle non-magnetic metal sheet (4). The driving electrodes (5) are fixed by a support frame (1). The photoelectric displacement sensor (6) is arranged at both ends of the suspension element (3) to measure The photoelectric displacement sensor (6) converts the collected position signal of the suspended element (3) into an electrical signal in real time and transmits the signal to the driving electrode controller (7). The driving electrode controller (7) calculates the difference between the electrical signal measured by the photoelectric displacement sensor (6) and the electrical signal measured by the suspended element (3) at a preset position to generate a control quantity that offsets the difference and inputs the control quantity into the high-voltage amplifier (8). The preset position is a position where the suspended element (3) is equidistant from the two photoelectric displacement sensors (6). The high-voltage amplifier (8) generates a corresponding control voltage through the amplification effect of the control quantity, and the bias signal provided by the circuit is processed by the addition circuit and the subtraction circuit to generate two signals with a difference of twice the control voltage.

[0049] like Figure 5As shown, the differential principle of the drive electrode (5) of the differential structure is that for the same control quantity output by the controller, two output signals with a difference of twice the control quantity are generated by the addition circuit and the subtraction circuit respectively. The two signals are input to the upper and lower groups of drive electrodes (5) respectively. The directions of the forces generated by the non-magnetic metal sheet (4) are opposite. The resultant force on the non-magnetic metal sheet (4) is the difference between the two forces, and the size of the difference is related to the control quantity. The differential structure can offset the influence of the reference value brought by the bias voltage.

[0050] The photoelectric displacement sensor (6) converts the position signal of the non-magnetic metal sheet (4) into an electrical signal in real time and transmits it to the driving electrode controller (7). The driving electrode controller (7) generates a control quantity to make the difference zero based on the difference between the electrical signal measured by the photoelectric displacement sensor (6) and the preset electrical signal, and inputs it into the high-voltage amplifier (8). The corresponding control voltage is generated by the amplification effect of the high-voltage amplifier (8) and inputted into the driving electrode (5). According to the principle of electrostatic suspension, the non-magnetic metal sheet (4) is induced by the control voltage on the driving electrode (5) to induce a corresponding electrostatic force, causing the position of the non-magnetic metal sheet (4) to change until the non-magnetic metal sheet (4) stabilizes at the preset position, that is, the difference between the electrical signal measured by the photoelectric displacement sensor (6) and the preset electrical signal is zero.

[0051] The size of the metal surface of the driving electrode (5) is selected based on the non-magnetic metal sheet (4), which is 4 mm × 2 mm. The distance between the driving electrode (5) and the non-magnetic metal sheet (4) can also be selected inversely using the control variable method, that is, when other conditions remain unchanged, the distance is selected with the best electromagnetic force linearity and the maximum electromagnetic force as the goal. In this example, 5 mm is selected.

[0052] The selection of the photoelectric displacement sensor (6) depends on the application background. For fields with high accelerometer resolution requirements, a high-resolution photoelectric displacement sensor (6) is selected, but it must be ensured that it works in the linear working area of ​​the photoelectric displacement sensor (6). The design of the controller depends on the application background. For fields with high accelerometer measurement range requirements, a neural network controller is waiting to be developed, and for fields with low measurement range requirements, an adaptive PID controller is waiting to be developed.

[0053] A measurement method for a diamagnetic electrostatic hybrid suspension accelerometer includes the following three steps:

[0054] Step S1, carrying out the installation of the anti-magnetic electrostatic hybrid suspension accelerometer. First, the driving electrode (5) is symmetrically installed on the support frame (1), the suspension element (3) is placed on the permanent magnet array (2), and the displacement of the suspension element (3) on the x-axis is limited by a thin rope. By adjusting the position between the permanent magnet array (2) and the suspension element (3), the non-magnetic metal sheet (4) is directly opposite the driving electrode (5); the position of the photoelectric displacement sensor (6) is adjusted so that the laser it emits is aligned with the bottom plate of the anti-magnetic suspension element (3), and the distance between the photoelectric displacement sensor (6) and the anti-magnetic suspension element (3) is ensured to be within the linear working area of ​​the photoelectric displacement sensor (6), thereby completing the installation of the anti-magnetic electrostatic hybrid suspension accelerometer.

[0055] Step S2, debugging the anti-magnetic electrostatic hybrid suspension accelerometer. By adjusting the exciter to change the magnitude and frequency of the acceleration signal, the amplitude and frequency and other characteristic parameters of the voltage difference signal output by the high-voltage amplifier (8) are measured and recorded, and a curve showing the change of the output voltage amplitude with the characteristic parameters of the acceleration signal is drawn. The experiment is repeated many times to obtain an average curve, revealing the performance parameters of the anti-magnetic electrostatic hybrid suspension accelerometer, such as the measurement range, linear region, linearity, sensitivity, resolution, response time, and repetition rate, thereby completing the debugging of the anti-magnetic electrostatic hybrid suspension accelerometer.

[0056] Step S3: Conduct actual testing of the anti-magnetic electrostatic hybrid suspension accelerometer. By adjusting the exciter, the characteristic parameters of the actual acceleration signal are changed and recorded. Simultaneously, the characteristic parameters of the acceleration signal measured by the anti-magnetic electrostatic hybrid suspension accelerometer, which uses the performance parameters determined during the debugging process as a carrier, are recorded. The actual acceleration signal and the test signal are compared and analyzed to determine the measurement accuracy, completing the actual testing of the anti-magnetic electrostatic hybrid suspension accelerometer.

[0057] A measuring method for an anti-magnetic electrostatic hybrid suspension accelerometer, the specific principle of which is as follows: taking a measured object performing simple harmonic oscillation along a horizontal line as an example, the measured object drives a permanent magnet array (2) to move, causing relative motion between an inertial element and the permanent magnet array (2), and the anti-magnetic suspension force exerted on a suspension element (3) is evenly distributed along the motion direction, so that the inertial element always has a tendency to perform horizontal linear motion relative to the permanent magnet array (2) at a determined suspension height; after a photoelectric displacement sensor (6) detects a position signal in real time, when the position of a non-magnetic metal sheet (4) shifts, a drive electrode controller (7) generates a corresponding control voltage, which is amplified by a high-voltage amplifier (8) and acts on a drive electrode (5), inducing an electrostatic force to act on the non-magnetic metal sheet (4) until it reaches a preset position.

[0058] At this time, the force balance equation between the suspension element (3) and the non-magnetic metal sheet (4) is:

[0059] mx=-kxr -f x x r +F d

[0060] Where m is the mass of the inertial element composed of the suspension element (3) and the non-magnetic metal sheet (4), x r is the relative displacement of the inertial element relative to the permanent magnet array (2), x is the absolute displacement of the inertial element, F d is the electrostatic driving force, which is the x-direction component of the total electrostatic force exerted by the driving electrode (5) on the non-magnetic metal sheet (4); k is the x-direction negative stiffness exerted on the suspension element (3) made of diamagnetic material in the permanent magnet array (2); f x It is the electromagnetic damping caused by motion in a magnetic field.

[0061] For the electrostatic driving force F d ,have

[0062]

[0063] F d =-K x x+K vx V com

[0064]

[0065]

[0066] Where ε0 is the absolute dielectric constant, ε r is the relative dielectric constant, K x , K vx is the equivalent stiffness of electrostatic force, V ref is the preset voltage, V con Feedback voltage is applied to the driving electrode controller (7), A is the electrode area, d is the nominal gap between the electrodes, F d The magnitude is determined by the voltage applied by the controller to the driving electrode (5). The relative dielectric constant is related to the distance between the non-magnetic metal sheet (4) and the driving electrode (5). When the non-magnetic metal sheet (4) is not large relative to the preset position during the vibration of the measured object, and the control voltage is small relative to the preset voltage, K x , K vx can be considered as a constant.

[0067] The measurement principle of the accelerometer is:

[0068]

[0069] Where G s (s) is the transfer function of the measurement link, G c(s) is the transfer function of the control box, G a (s) is the transfer function of the high-voltage amplifier (8), and the acceleration signal measured by the accelerometer and the control signal of the control box present the above quantitative relationship. During the debugging phase of the anti-magnetic electrostatic hybrid suspension accelerometer, that is, when experimentally testing the input and output curves of the anti-magnetic electrostatic hybrid suspension accelerometer and measuring performance parameters such as range, sensitivity, and resolution, the control voltage is the input of the anti-magnetic electrostatic hybrid suspension accelerometer, and the acceleration signal is the output of the anti-magnetic electrostatic hybrid suspension accelerometer; after the debugging is completed and used in actual applications, the determined performance parameters are used as a carrier, and the corresponding acceleration signal is output according to the voltage change caused by the acceleration signal to be measured, such as Figure 6 Shown is a schematic diagram of input signal and output signal curves; Figure 7 Schematic diagram of the curve showing the amplitude ratio of input and output signals changing with frequency.

[0070] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A diamagnetic electrostatic hybrid suspension accelerometer, characterized in that: It comprises a support frame (1), a permanent magnet array (2), a suspension element (3) made of diamagnetic material, a non-magnetic metal sheet (4), a driving electrode (5), a photoelectric displacement sensor (6), a driving electrode controller (7), and a high-voltage amplifier (8); The permanent magnet array (2) is a groove-type permanent magnet array (2) composed of three groups of single pairs of permanent magnets with exactly the same shape and magnetization. Each group of single pairs of permanent magnet arrays (2) is composed of two axially magnetized rectangular permanent magnets of the same size, opposite magnetization strength directions, and equal size. The suspension element (3) and the non-magnetic metal sheet (4) are assembled together by glue. The suspension element (3) is made of three rectangular thin sheets made of diamagnetic material, which have the same width. One of the rectangular thin sheets is longer and serves as the suspension element bottom plate. The other two are of equal length and constitute the suspension element (3) side plates. The non-magnetic metal sheet (4) is a rectangular thin sheet with a length greater than the distance between the two side plates, connecting the suspension element (3) side plates together. The suspension element (3) is located inside the groove of the permanent magnet array (2). The permanent magnet array (2) generates a force on the suspension element (3) that points to the minimum value point of the total potential energy inside the groove, thereby realizing passive stable suspension of the suspension element (3) and the non-magnetic metal sheet (4) in the non-measurement axis direction. The driving electrode (5) is placed opposite to the non-magnetic metal sheet (4). The driving electrode (5) adopts a differential structure and is placed at both ends of the suspension element (3) in a symmetrical distribution. When the driving electrode (5) is energized, it generates an attractive force on the non-magnetic metal sheet (4) in the middle. The photoelectric displacement sensor (6) is arranged at both ends of the suspension element (3) to measure the position signal of the suspension element (3). The photoelectric displacement sensor (6) converts the collected position signal of the suspension element (3) into an electrical signal in real time and transmits it to the driving electrode controller (7). The driving electrode controller (7) generates a control quantity to make the difference zero based on the difference between the electrical signal measured by the photoelectric displacement sensor (6) and a preset electrical signal, and inputs the control quantity into the driving electrode (5). The preset position signal is then generated. The signal is amplified by a high-voltage amplifier (8) to generate a corresponding control voltage. The control voltage in the high-voltage amplifier (8) is processed by an addition circuit and a subtraction circuit to generate two output signals with a difference of twice the control amount, which are respectively input into the front and rear groups of driving electrodes (5). The non-magnetic metal sheet (4) is induced to generate a corresponding electrostatic force by the control voltage in the driving electrodes (5). The directions of the forces generated by the two groups of driving electrodes (5) on the non-magnetic metal sheet (4) are opposite. The resultant force on the non-magnetic metal sheet (4) is the difference between the two forces, so that the positions of the suspension element (3) and the non-magnetic metal sheet (4) change until the non-magnetic metal sheet (4) stabilizes at a preset position, so that the suspension element (3) in the measurement axis direction is actively and stably suspended.

2. The antimagnetic electrostatic hybrid suspension accelerometer according to claim 1, characterized in that: The magnetic pole arrangement of the permanent magnet array (2) adopts an axially magnetized permanent magnet in a mixed arrangement of "Opposite" and "Halbach", and each single pair of "Opposite" arrays is composed of two axially magnetized rectangular permanent magnets of the same size, opposite magnetization strength directions and equal size, and the relative positions are arranged according to the "Halbach" array.

3. The antimagnetic electrostatic hybrid suspension accelerometer according to claim 1, characterized in that: The ratio of the sum of the volumes of the side plates and the non-magnetic metal sheets (4) of the suspension element (3) to the volume of the bottom plate of the suspension element (3) is less than 3:2 when thin sheets of the same thickness are selected.

4. The measurement method of a diamagnetic electrostatic hybrid suspension accelerometer according to claim 1, characterized in that: The accelerometer measurement method mainly includes the following three steps: Step S1, carrying out the installation of an anti-magnetic electrostatic hybrid suspension accelerometer; first, a driving electrode (5) is symmetrically installed on a support frame (1), a suspension element (3) is placed on a permanent magnet array (2), and a thin rope is used to limit the displacement of the suspension element (3) on the x-axis, and the position between the permanent magnet array (2) and the suspension element (3) is adjusted so that the non-magnetic metal sheet (4) is facing the driving electrode (5); The position of the photoelectric displacement sensor (6) is adjusted so that the laser light it emits is aligned with the bottom plate of the suspension element (3) made of the diamagnetic material, and the distance between the photoelectric displacement sensor (6) and the suspension element (3) made of the diamagnetic material is within the linear working area of ​​the photoelectric displacement sensor (6), thereby completing the installation of the diamagnetic electrostatic hybrid suspension accelerometer; Step S2, carrying out debugging of an anti-magnetic electrostatic hybrid suspension anti-magnetic suspension accelerometer, changing the magnitude and frequency of the acceleration signal by adjusting the exciter, measuring and recording the amplitude and frequency of the voltage difference signal output by the high-voltage amplifier (8) at this time, drawing a curve of the output voltage amplitude changing with the characteristic parameters of the acceleration signal, repeating the experiment multiple times, obtaining an average curve, obtaining the measurement range, linear region, linearity, sensitivity, resolution, response time, and repetition rate of the anti-magnetic electrostatic hybrid suspension accelerometer, and completing the debugging of the anti-magnetic electrostatic hybrid suspension accelerometer; Step S3: Conduct an actual test of an anti-magnetic electrostatic hybrid suspension accelerometer. By adjusting the exciter, the characteristic parameters of the actual acceleration signal are changed and recorded. At the same time, the characteristic parameters of the acceleration signal measured by the anti-magnetic electrostatic hybrid suspension accelerometer based on the performance parameters determined during the debugging process are recorded. The actual acceleration signal and the test signal are compared and analyzed to obtain the measurement accuracy, thereby completing the actual test of the anti-magnetic electrostatic hybrid suspension accelerometer.

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