Apparatus and method for accelerometer resolution calibration

Abstract

The application discloses a device and method for accelerometer resolution calibration, which comprises airflow isolation structure, vibration isolation table structure and gravitational acceleration generation structure; the airflow isolation structure and the vibration isolation table are used for interference effect isolation, and the gravitational acceleration generation structure is used for generating stable and accurate change of gravitational acceleration. The application utilizes a pair of metal balls with equal mass to rotate at a certain frequency and radius, generates the required accurate change of gravitational acceleration, isolates the interference effects such as earthquakes, airflow and magnetic field through the vibration isolation table and the airflow isolation structure, stably and accurately excites the gravitational acceleration of the accelerometer placed on the vibration isolation table, then records the readout data of the accelerometer, and obtains the calibration result by difference processing of the data before and after excitation. The application is used for ground test of high-precision accelerometer, and can realize 10 ‑8 m / s 2 ~10 ‑10 m / s 2 order high-precision resolution calibration.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of precision measurement, and more particularly, to a device and method for accelerometer resolution calibration. BACKGROUND

[0002] High-precision accelerometers have important application significance in satellite gravity measurement and space wave detection. The resolution of electrostatic accelerometers in satellite gravity measurement needs to reach 10 -9 m / s 2 or more, and the resolution of electrostatic accelerometers in space gravitational wave detection needs to reach 10 -15 m / s 2 or more. The requirements for resolution testing of such instruments on the ground are becoming higher and higher. Since the ground vibration noise power spectral density is generally 10 -7 ~ 10 -8 m / s 2 / Hz 1 / 2 or more, far exceeding the current and future testing resolution requirements, new shock isolation testing methods must be developed to meet the future testing needs of high-precision accelerometers.

[0003] The current testing method for high-precision accelerometers is to generate the required input excitation by moving or tilting the measured object. Since the measured accelerometer needs to be accurately installed and powered, the installation and movement process may cause measurement errors. At present, most people believe that the resolution of the accelerometer is only limited by noise, and the resolution can be calculated by integrating the feedback control voltage noise power spectral density in the corresponding bandwidth. Although this view is correct, this method is not a direct measurement of the resolution. SUMMARY

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a device and method for accelerometer resolution calibration, which aims to solve the problems of low evaluation accuracy and inability to directly measure the resolution of the traditional accelerometer resolution testing method.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a device for accelerometer resolution calibration, comprising: an airflow isolation structure, a shock isolation table structure, and a gravitational acceleration generation structure.

[0006] The airflow isolation structure is used to isolate airflow disturbance and comprises a first isolation component and a second isolation component. The shock isolation table structure is placed inside the first isolation component, and the gravitational acceleration excitation generation structure is placed inside the second isolation component.

[0007] The shock isolation table structure is used to isolate ground vibration and carry the accelerometer to be calibrated, so that it is separated from the ground.

[0008] The gravity acceleration excitation generating structure is used to generate a gravity acceleration excitation for the accelerometer measurement to realize calibration of the acceleration resolution.

[0009] The isolation platform structure comprises a platform, a passive isolation component and an active isolation component; the passive isolation component is fixed to the ground and the platform is suspended by a pendulum, the platform is used to carry the accelerometer, the platform and the passive isolation component are used to attenuate ground vibration higher than the natural frequency of the pendulum, and the active isolation component is installed on both sides of the platform in the horizontal direction to control the horizontal movement of the platform to offset the horizontal vibration received by the platform.

[0010] The gravity acceleration excitation generating structure comprises a turntable, a tray and two metal balls; the two metal balls are fixed on both sides of the tray, the tray is fixed to the upper surface of the turntable, the turntable is used to drive the tray to rotate, so that the two metal balls are driven to rotate to generate a periodically changing gravity relative to the accelerometer, the difference between the maximum value and the minimum value of the periodically changing gravity is less than or equal to the gravity value corresponding to the resolution of the accelerometer; since it is double ball rotation, the rotation frequency of the turntable is equal to half of the test frequency of the accelerometer; at the test frequency, the acceleration amplitude spectrum processing result of the accelerometer measured when the tray has no metal ball and the turntable rotates is taken as a first measurement value, and the acceleration amplitude spectrum processing result of the accelerometer measured when the tray has a metal ball and the turntable rotates is taken as a second measurement value, the difference between the second measurement value and the first measurement value corresponds to the calibration result of the resolution of the accelerometer.

[0011] In one possible example, the first isolation component is a closed cavity, and the second isolation component is a shield.

[0012] In one possible example, the passive isolation component comprises a cubic frame.

[0013] The cubic frame is fixed to the ground; one end of the pendulum is suspended at the top of the cubic frame, and the other end is fixed to the platform.

[0014] In one possible example, the active isolation component comprises a vibration sensor, a controller and a feedback force actuator.

[0015] The vibration sensor is used to measure the vibration of the platform in the horizontal direction.

[0016] The controller is used to control the feedback force actuator to work according to the vibration measured by the vibration sensor in the horizontal direction, so that the platform moves in the opposite direction of the horizontal vibration.

[0017] The feedback force actuator is used to control the horizontal movement of the platform.

[0018] In one possible example, the mass of the metal balls is selected to be less than the limit bearing capacity of the turntable, and the maximum and minimum values of the gravitational acceleration required are determined according to the mass of the metal balls, the acceleration resolution of the accelerometer in a certain direction to be tested, the formula of universal gravitation and the formula of Newton's second law; wherein the difference between the maximum and minimum values of the gravitational acceleration is less than or equal to the acceleration resolution; for the direction along the line connecting the center of mass of the accelerometer and the center of the turntable, when the gravitational acceleration is maximum, the line connecting the two metal balls passes through the center of mass of the accelerometer, and when the gravitational acceleration is minimum, the line connecting the two metal balls is perpendicular to the line connecting the center of mass of the accelerometer and the center of the turntable.

[0019] The distance from the center of the turntable to the test mass of the accelerometer and the distance from the center of the turntable to the metal balls are determined according to the maximum and minimum values of the gravitational acceleration along the line connecting the center of mass of the accelerometer and the center of the turntable.

[0020] Specifically, it is necessary to ensure that the difference between the maximum and minimum values of the periodically varying gravitational acceleration is less than or equal to the resolution of the test required gravitational value.

[0021] It should be noted that in order to calibrate the acceleration resolution of the accelerometer to be calibrated, it is necessary to provide the accelerometer with a periodically varying acceleration excitation, and the difference between the maximum and minimum values of the periodically varying acceleration is equal to or less than its resolution. In the present application, the two metal balls are rotated to provide a periodically varying acceleration for the accelerometer. The law of acceleration change is related to the distance of the two metal balls relative to the accelerometer. When the accelerometer can measure the difference between the maximum and minimum values of the combined acceleration generated by the two metal balls, it is considered that the resolution of the accelerometer meets the requirements and is qualified.

[0022] In one specific example, for example, the design resolution of the accelerometer is 5×10 -9 m / s 2 , and it is necessary to design a periodically varying gravitational acceleration with a difference of 5×10 -9 m / s 2 (or less) to test whether it is qualified, wherein the acceleration difference is the difference between the maximum acceleration and the minimum acceleration.

[0023] In a second aspect, the present application provides a method for calibrating the resolution of an accelerometer, comprising the following steps:

[0024] The acceleration of the accelerometer is measured when the turntable is rotating under no load, and the amplitude spectrum processing result is taken as the first measurement value; the rotation frequency of the turntable is equal to half of the test frequency of the accelerometer;

[0025] The control turntable drives the two metal balls to rotate, so that the two metal balls are driven to rotate to generate a periodically changing gravity relative to the accelerometer; wherein the difference between the maximum value and the minimum value of the periodically changing gravity is less than or equal to the gravity value corresponding to the resolution of the accelerometer;

[0026] The control accelerometer measures the acceleration of the metal balls driven by the turntable to rotate, and the amplitude spectrum processing result is taken as a second measurement value;

[0027] The difference between the second measurement value and the first measurement value is taken as a calibration result of the resolution of the accelerometer.

[0028] In one possible example, the method further comprises the following steps:

[0029] The accelerometer is suspended by a vibration isolation platform structure to be separated from the ground and to isolate the ground vibration; wherein the vibration isolation platform structure comprises a platform, a passive vibration isolation component and an active vibration isolation component; the passive vibration isolation component is fixed to the ground and suspends the platform by a pendulum, the platform is used to carry the accelerometer, the platform and the passive vibration isolation component are used to attenuate the ground vibration higher than the natural frequency of the pendulum, and the active vibration isolation component is installed on both sides of the platform in the horizontal direction to control the horizontal movement of the platform to offset the horizontal vibration received by the platform.

[0030] In one possible example, the method further comprises the following steps:

[0031] The accelerometer and the turntable are placed inside a first isolation component;

[0032] The turntable and the metal balls carried by the turntable are placed inside a second isolation component; the first isolation component and the second isolation component are used to isolate the airflow disturbance and the magnetic field disturbance.

[0033] In one possible example, the mass of the metal balls is selected to be less than the limit carrying capacity of the turntable, the maximum value and the minimum value of the required gravitational acceleration are determined according to the mass of the metal balls, the acceleration resolution of the accelerometer in a certain direction to be tested, the universal gravitation formula and the second law of Newton; wherein the difference between the maximum value and the minimum value of the gravitational acceleration is less than or equal to the acceleration resolution; for the direction along the line connecting the center of mass of the accelerometer and the center of the turntable, when the gravitational acceleration is maximum, the line connecting the two metal balls passes through the center of mass of the accelerometer, and when the gravitational acceleration is minimum, the line connecting the two metal balls is perpendicular to the line connecting the center of mass of the accelerometer and the center of the turntable; the distance from the center of the turntable to the test mass of the accelerometer and the distance from the center of the turntable to the metal balls are determined according to the maximum value and the minimum value of the gravitational acceleration along the direction of the line connecting the center of mass of the accelerometer and the center of the turntable.

[0034] Overall, compared with the prior art, the above technical solutions conceived by the present application have the following beneficial effects:

[0035] The application provides an accelerometer resolution calibration device and method, which utilizes an isolation platform structure, cooperates active and passive isolation components, and can measure the noise floor of the measured accelerometer on the isolation platform to be 2*10 -9 m / s 2 / Hz 1 / 2 , and can realize the resolution test level of 10 -10 m / s 2 .

[0036] The application provides an accelerometer resolution calibration device and method, which only needs to adjust the gravity acceleration generation structure parameters when the ground resolution test of the accelerometer is carried out, and can obtain the high-precision gravity standard of 10 -8 m / s 2 to 10 -10 m / s 2 order according to the universal gravitation formula.

[0037] The application provides an accelerometer resolution calibration device and method, which utilizes the difference data processing method, can maximally reduce the influence of the environmental interference effect in the resolution test process, and can realize the direct test of the high-precision accelerometer horizontal axis based on the isolation swing platform by combining the isolation swing platform, the universal gravitation standard and the difference measurement method, and has the intuitive test result advantage. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 Fig. 1 is a structural schematic diagram of an accelerometer resolution calibration device provided by an embodiment of the application;

[0039] Figure 2 Fig. 2 is a flow chart of an accelerometer resolution calibration method provided by an embodiment of the application;

[0040] Figure 3 Fig. 3 is a relative position diagram of a metal ball and an accelerometer when the gravity acceleration is maximum;

[0041] Figure 4 Fig. 4 is a relative position diagram of a metal ball and an accelerometer when the gravity acceleration is minimum;

[0042] In all the drawings, the same reference signs are used to represent the same elements or structures, in which: 1 is a measured accelerometer, 2 is an inclination adjusting platform, 3 is a vacuum cavity, 4 is a shielding cover, 5 is a platform, 6 is a passive isolation component, 7 is an active isolation component, 8 is a turntable, 9 is a tray, 10 is a metal ball, and 11 is a turntable support. DETAILED DESCRIPTION

[0043] For the convenience of understanding, the English abbreviations and related technical terms involved in the embodiments of the present application are explained and described below.

[0044] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0045] The application discloses an accelerometer resolution calibration method and device, which comprises an airflow isolation structure, a shock isolation platform structure and a gravitational acceleration generation structure, wherein the airflow isolation structure further comprises a vacuum cavity and a shielding cover, the shock isolation platform structure further comprises a platform, a passive shock isolation component and an active shock isolation component, and the gravitational acceleration generation structure further comprises a turntable, a tray, a metal ball and a turntable support; the airflow isolation structure is used for isolating low-frequency airflow disturbance and magnetic field disturbance, the shock isolation platform is used for realizing ground vibration isolation, and the gravitational acceleration generation structure is used for generating stable and accurate change gravitational acceleration, and is used for high-precision resolution test of the accelerometer. -8 m / s 2 ~10 -10 m / s 2 order high-precision resolution calibration.

[0046] The application provides an accelerometer resolution test device, which comprises an airflow isolation structure A, a shock isolation platform structure B and a gravitational acceleration generation structure C; the airflow isolation structure A is used for realizing low-frequency airflow isolation and magnetic field disturbance isolation; the shock isolation platform structure B is used for realizing ground vibration isolation; and the gravitational acceleration generation structure C is used for generating resolution calibration gravitational standard signals.

[0047] Further, the airflow isolation structure A comprises a vacuum cavity and a shielding cover; the vacuum cavity is fixed on a flat shock isolation foundation and is used for isolating airflow generated by a laboratory air conditioner or personnel activities; the shielding cover is fixedly connected with the turntable support, covers the metal ball, the tray and the turntable and leaves a rotating space, the surface of the shielding cover is covered with magnetic shielding material, and the shielding cover is used for isolating airflow and magnetic field disturbance generated by rotation of the turntable.

[0048] The isolation platform structure B comprises a platform, a passive isolation component and an active isolation component; the platform is used for placing a vibration sensor and an instrument to be tested, such as a high-precision accelerometer; the passive isolation component is fixed to a flat ground and is used for supporting or suspending the test platform, and forms a passive isolation structure with the platform to attenuate vibration higher than the natural frequency; the active isolation component can be installed in two orthogonal directions around the platform in the horizontal direction, and comprises a vibration sensor, a controller and a feedback force actuator, and can intervene in work when needed, so that the isolation capacity of the isolation platform structure is improved.

[0049] The gravity acceleration generation structure C comprises a turntable, a tray, a metal ball and a turntable support. The turntable is installed on the turntable support, the tray is fixed to the upper surface of the turntable, and the metal ball is placed in the groove of the tray, is constrained on the tray by gravity and is convenient to take and place, and is used for generating a changing gravity when being driven to rotate by the turntable.

[0050] As an embodiment of the present application, a vacuum cavity is used for isolating air flow generated by a laboratory air conditioner or personnel activities; a shielding cover is placed above the turntable support, covers the metal ball, the tray and the turntable and leaves a rotating space, the surface of the shielding cover is covered with magnetic shielding material, and is used for isolating air flow and magnetic field disturbance generated by rotation of the turntable. The isolation platform structure B mainly comprises a passive isolation component composed of a four-wire pendulum or a tilt compensation pendulum, an active isolation component composed of a vibration sensor, a controller and a feedback force actuator, and a platform for bearing the tested accelerometer. The passive isolation component works alone or together with the active isolation component to realize isolation of the test platform. The turntable is fixed to the turntable support, the tray is fixed to the rotating surface of the turntable, the metal ball is placed in the groove of the tray, is constrained on the tray by gravity and is convenient to take and place, and is used for generating a changing gravity when being driven to rotate by the turntable.

[0051] The present application provides an accelerometer resolution calibration device, which uses an air flow isolation structure to isolate the influence of low-frequency air flow and magnetic field disturbance, an isolation platform structure to isolate vibration transmitted to a test platform from the ground at a certain isolation rate, and a gravity acceleration generation structure to generate a weak gravity acceleration required for testing. The tested accelerometer installed on the isolation platform can reach a test resolution of 10 -10 m / s 2 order in the 0.1Hz-1Hz frequency band under the condition that the performance of the accelerometer permits. The device can greatly improve the ground verification level of high-precision accelerometers such as electrostatically suspended accelerometers, and has important significance in the field of precise instrument evaluation.

[0052] Figure 1 A principle diagram of an accelerometer resolution calibration device provided by an embodiment of the present application is shown, and only parts related to the embodiment of the present application are shown for convenience of description.

[0053] The airflow isolation structure A includes, but is not limited to, a vacuum chamber 2 and a shield 10. The vacuum chamber 2 is used to isolate the airflow generated by the laboratory air conditioner or personnel activities, and can also be a closed cavity that is not evacuated. The shield 10 is placed above the turntable support, covering the metal ball, tray and turntable and leaving room for rotation. Its surface is covered with magnetic shielding material to isolate the airflow and magnetic field disturbances generated by the rotation of the turntable.

[0054] The vibration isolation table structure B includes, but is not limited to: an active vibration isolation component 3, a passive vibration isolation component 4, and a platform 5. The passive vibration isolation component 4 serves two purposes: supporting the platform 5 and attenuating vibrations above its natural frequency. The platform 5 is connected to the passive vibration isolation component 4 and is used to house the vibration sensor and the accelerometer under test, and to fix the force-bearing part of the feedback force actuator of the active vibration isolation component 3. The active vibration isolation component 3 includes, but is not limited to: a vibration sensor, a controller, and a feedback force actuator. The vibration sensor is placed on the platform 5 and connected to the controller to sense platform vibrations and transmit the vibration signal to the controller. The controller is placed on the platform or outside the platform and is electrically connected to the vibration sensor and the feedback force actuator. It is used to generate output control signals based on the vibration sensor input using a control algorithm to drive the feedback force actuator. The force-bearing end of the feedback force actuator is installed on the test platform, and the force-applying end is installed at the bottom of the vacuum chamber. It is electrically connected to the controller and generates corresponding feedback control force based on the control signal to counteract platform vibrations. A preferred example of a feedback force actuator is a voice coil motor.

[0055] The gravitational acceleration generating structure C includes, but is not limited to: a turntable, a tray, a metal sphere, and a turntable support. The turntable is fixed to the turntable support, the tray is fixed to the turntable's rotation surface, and the metal sphere is placed in a groove on the tray, constrained by gravity and easily accessible. When rotated by the turntable, it generates varying gravitational force. The turntable support, turntable, and tray, together with the metal sphere, achieve the generation of varying gravitational acceleration.

[0056] like Figure 2 As shown in the figure, this embodiment of the invention provides an accelerometer resolution calibration method for performing acceleration resolution tests. The specific process is as follows:

[0057] S1. Before testing, determine the corresponding test frequency and theoretical acceleration value R based on the accuracy level of the accelerometer 1 to be tested. theory For example, if the test frequency is 0.5Hz, the test acceleration magnitude is 5×10. -9 m / s 2 ;

[0058] In S1, based on the bias voltage V b The design curve for the noise power spectral density of the accelerometer under test 1 at 15V is shown. The noise spectral density at 0.1Hz is 10. -10 m / s2 / Hz 1 / 2 order of magnitude.

[0059] S2. Determine the mass of the metal ball 10 according to the performance of the turntable 8;

[0060] In S2, since the load bearing capacity of the turntable 8 device is limited, according to the relationship curve between the distance of the object placed on the table surface from the center and the maximum load bearing capacity of the turntable 8 at that distance in the manual of the turntable 8, a metal ball 10 with a mass of Mkg is selected as the attracting mass and placed in the circular hole on both sides of the flat aluminum plate fixed on the turntable 8.

[0061] S3. Determine the theoretical value of the test acceleration R according to the universal gravitation formula and the M value calculated in S2. theory The distance L of the test mass from the center of the turntable 8 and the distance R of the metal ball 10 from the center of the turntable 8 in the corresponding accelerometer under test;

[0062] In order to obtain a gravitational acceleration difference of 10 -9 m / s 2 order of magnitude generated by the two metal balls 10 on the accelerometer, it is necessary to first determine the maximum value a max and the minimum value a min of the gravitational acceleration, so as to obtain the distance L of the test mass from the center of the turntable 8 and the distance R of the metal ball 10 from the center of the turntable 8, the range being that the turntable can freely rotate without contacting the shielding cover, and the shielding cover does not contact the accelerometer, and their relationship is as follows:

[0063] As shown in Figure 3 , taking the component of the gravitational acceleration along the line connecting the accelerometer under test 1 and the center of the turntable 8 as an example, when the line connecting the two metal balls 10 is parallel to the direction of this gravitational acceleration component, the maximum value of the gravitational acceleration is:

[0064]

[0065] where G is the universal gravitational constant.

[0066] As shown in Figure 4 , when the line connecting the two metal balls 10 is perpendicular to the direction of this gravitational acceleration component, the minimum value of the gravitational acceleration is:

[0067]

[0068] where the distance of each metal ball from the center of the turntable is between centimeters and decimeters, and the distance from the center of the turntable to the center of the test mass is of the order of decimeters.

[0069] The required gravitational acceleration signal for testing is:

[0070] R theory = amax -a min

[0071] S4. Without placing the metal ball 10, rotate the turntable 8 at a set test frequency, and record the time-domain data of the accelerometer 1 to be tested;

[0072] The specific method of S4 is that after the pendulum isolation enters the optimal state and the output data of the accelerometer is stable, the computer remotely connects the turntable 8, runs the turntable 8 control program, and makes it rotate at a uniform speed according to the required rotation period of the calibration experiment, and records the output data of the horizontal axis of the accelerometer 1 to be tested;

[0073] S5. Keep other states unchanged, place the metal ball 10, still rotate the turntable 8 at a set test frequency in S4, and record the output data of the accelerometer 1 to be tested again;

[0074] The specific method of S5 is that the active isolation control is closed, the rotation of the turntable 8 is stopped, the shielding cap is removed, the two metal balls 10 are symmetrically placed, the pendulum isolation is started, and after the pendulum is stable for 0.5-1 hours, the rotation of the turntable 8 is remotely controlled and started, and the turntable 8 is rotated at a uniform speed according to the period set in S4, and the output data of the horizontal axis of the accelerometer is recorded;

[0075] S6. Process the data recorded twice in the frequency domain respectively, and subtract the processing result of the case without the ball from the processing result of the case with the ball, that is, the resolution test result R test ;

[0076] The specific method of S6 is:

[0077] S61. Obtain the time-domain data sequence (length N, generally even) from the accelerometer 1 to be tested;

[0078] S62. Fourier transform the time-domain data sequence to obtain the amplitude spectrum;

[0079] S63. Take the single-side amplitude spectrum, that is, take the first half data length (0-N / 2) after taking the modulus of the amplitude spectrum;

[0080] S64. Multiply the single-side amplitude spectrum by 2 / N to obtain the time-domain amplitude;

[0081] S65. Take the amplitude value corresponding to the test frequency point as the resolution test result R test .

[0082] S7. Compare the resolution test result R test with the theoretical calculation value R theory , if 0.5≤R test / R theory ≤1.5, the test is passed.

[0083] In the S7, the ratio of the measured output amplitude of the response acceleration of the to-be-tested accelerometer 1 to the theoretical output amplitude should be within the range of 50% to 150% according to the national metrological specification applicable to linear accelerometers.

[0084] It should be understood that expressions such as "include" and "may include" used in the present application indicate the presence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In the present application, terms such as "include" and / or "have" can be interpreted as indicating the presence of a specific characteristic, number, operation, constituent element, component, or combination thereof, but cannot be interpreted as excluding the presence or addition of one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0085] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed terms. For example, the expression "A and / or B" can include A, can include B, or can include both A and B.

[0086] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be understood broadly, for example, "connection" can be detachable connection, or can be non-detachable connection; can be direct connection, or can be indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative positional relationship after connection is unchanged. "Rotational connection" means that the relative rotation after connection is allowed. "Sliding connection" means that the relative sliding after connection is allowed. The orientation terms mentioned in the embodiments of the present application, such as "top", "bottom", "inner", "outer", "left", "right", etc., are only the directions of the drawings, therefore, the orientation terms used are for better and clearer illustration and understanding of the embodiments of the present application, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0087] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A device for calibrating accelerometer resolution, characterized in that, include: Airflow isolation structure, vibration isolation table structure and gravitational acceleration generation structure; The airflow isolation structure is used to isolate airflow disturbances and magnetic field disturbances. It includes a first isolation component and a second isolation component. The second isolation component is used to isolate the airflow and magnetic field disturbances generated by the rotation of the turntable. The vibration isolation table structure is placed inside the first isolation component, and the gravitational acceleration excitation generating structure is placed inside the second isolation component. The vibration isolation platform structure is used to isolate ground vibrations and to support the accelerometer to be calibrated, thus detaching it from the ground. The gravitational acceleration excitation generation structure is used to generate gravitational acceleration excitation for accelerometer measurement, so as to achieve the calibration of acceleration resolution; The vibration isolation table structure includes: a platform, a passive vibration isolation component, and an active vibration isolation component; wherein, the passive vibration isolation component is fixed to the ground and the platform is suspended by a cycloid, the platform is used to carry an accelerometer, the platform and the passive vibration isolation component are used to attenuate ground vibrations higher than the natural frequency of the cycloid, and the active vibration isolation component is installed on both sides of the platform in the horizontal direction to control the horizontal movement of the platform to counteract the horizontal vibrations received by the platform. The gravitational acceleration excitation generation structure includes: a turntable support, a turntable, a tray, and two metal balls of equal mass. The two metal balls are fixed to opposite sides of the tray and constrained by gravity. The tray is fixed to the upper surface of the turntable, and the turntable is fixed to the turntable support. The turntable drives the tray to rotate, causing the two metal balls to generate a periodically varying gravitational force relative to the accelerometer. The difference between the maximum and minimum values ​​of this periodically varying gravitational force is less than or equal to the gravitational force value corresponding to the accelerometer resolution. The rotation frequency of the turntable is equal to half the accelerometer testing frequency. At the testing frequency, the acceleration amplitude spectrum processing result when the accelerometer measures the tray without metal balls and the turntable rotating is taken as the first measurement value, and the acceleration amplitude spectrum processing result when the accelerometer measures the tray with metal balls and the turntable rotating is taken as the second measurement value. The difference between the second and first measurement values ​​corresponds to the accelerometer resolution calibration result.

2. The apparatus according to claim 1, characterized in that, The first isolation component is a closed cavity, and the second isolation component is a shield.

3. The apparatus according to claim 1, characterized in that, The passive isolation assembly includes a cubic frame; The cube frame is fixed to the ground; one end of the cycloid is suspended from the top of the cube frame, and the other end is fixed to the platform.

4. The apparatus according to claim 1, characterized in that, The active vibration isolation assembly includes: a vibration sensor, a controller, and a feedback force actuator; The vibration sensor is used to measure the horizontal vibration of the platform; The controller is used to control the feedback force actuator to work based on the horizontal vibration measured by the vibration sensor, so that the platform moves in the opposite direction of the horizontal vibration. The feedback force actuator is used to control the horizontal movement of the platform.

5. The apparatus according to any one of claims 1 to 4, characterized in that, Select a metal ball mass less than the turntable's ultimate load-bearing capacity. Determine the maximum and minimum values ​​of the required gravitational acceleration based on the metal ball mass, the acceleration resolution of the accelerometer in a certain direction to be tested, the universal gravitation formula, and Newton's second law formula. The difference between the maximum and minimum gravitational acceleration values ​​is less than or equal to the acceleration resolution. For the direction along the line connecting the accelerometer's center of mass and the turntable center, when the gravitational acceleration is maximum, the line connecting the two metal balls passes through the accelerometer's center of mass; when the gravitational acceleration is minimum, the line connecting the two metal balls is perpendicular to the line connecting the accelerometer's center of mass and the turntable center. The distance from the turntable center to the accelerometer test mass and the distance from the metal ball to the turntable center are determined based on the maximum and minimum values ​​of the gravitational acceleration along the line connecting the accelerometer's center of mass and the turntable center.

6. A method for accelerometer resolution calibration, the method being applied to the apparatus as described in any one of claims 1 to 5, characterized in that, Includes the following steps: The accelerometer is controlled to measure the acceleration of the turntable when it is rotating under no-load, and the amplitude spectrum processing result is used as the first measurement value; the rotation frequency of the turntable is equal to half of the accelerometer test frequency; The control turntable drives two metal balls to rotate, so that the two metal balls generate a periodically changing gravitational force relative to the accelerometer when they are driven to rotate; wherein the difference between the maximum and minimum values ​​of the periodically changing gravitational force is less than or equal to the gravitational force value corresponding to the resolution of the accelerometer; The accelerometer is controlled to measure the acceleration of the metal ball as the turntable rotates, and the amplitude spectrum processing result is used as the second measurement value. The difference between the second measurement and the first measurement is used as the calibration result of the accelerometer resolution.

7. The method according to claim 6, characterized in that, It also includes the following steps: An accelerometer is suspended off the ground using a vibration isolation platform structure, thus isolating it from ground vibrations. The vibration isolation platform structure includes a platform, a passive vibration isolation component, and an active vibration isolation component. The passive vibration isolation component is fixed to the ground and suspends the platform via a cycloid. The platform supports the accelerometer. The platform and the passive vibration isolation component attenuate ground vibrations higher than the natural frequency of the cycloid. The active vibration isolation component is installed on both sides of the platform in the horizontal direction to control the horizontal movement of the platform and counteract horizontal vibrations experienced by the platform.

8. The method according to claim 6 or 7, characterized in that, It also includes the following steps: The accelerometer and turntable are placed inside the first isolation assembly; The turntable and the metal ball it carries are placed inside the second isolation assembly; the first and second isolation assemblies are used to isolate airflow disturbances and magnetic field disturbances.

9. The method according to claim 6 or 7, characterized in that, Select a metal ball mass less than the turntable's ultimate load-bearing capacity. Based on the metal ball's mass, the accelerometer's acceleration resolution in a specific direction to be tested, the universal gravitation formula, and Newton's second law, determine the required maximum and minimum gravitational acceleration values. The difference between the maximum and minimum gravitational acceleration values ​​is less than or equal to the acceleration resolution. Along the line connecting the accelerometer's center of mass and the turntable's center, when the gravitational acceleration is maximum, the line connecting the two metal balls passes through the accelerometer's center of mass; when the gravitational acceleration is minimum, the line connecting the two metal balls is perpendicular to the line connecting the accelerometer's center of mass and the turntable's center. Determine the distance from the turntable's center to the accelerometer's test mass and the distance from the metal ball to the turntable's center based on the maximum and minimum gravitational acceleration values ​​along the line connecting the accelerometer's center of mass and the turntable's center.

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