Accelerometer nonlinear coefficient identification method and device

Abstract

The invention belongs to the field of accelerometers, and particularly discloses an accelerometer nonlinear coefficient identification method and device, and the method comprises the steps: obtaining the amplitude-frequency response information of an accelerometer; the amplitude-frequency response information comprises gain information at different frequency points; the gain is the ratio of the accelerometer response corresponding to the acceleration input at the corresponding frequency point to the accelerometer response corresponding to the same-amplitude constant acceleration input; the gain of the under-damping accelerometer in a first frequency band is greater than 1, and the gain in a second frequency band is close to 1; setting a plurality of input accelerations in combination with the amplitude-frequency response information, so that a plurality of responses of the accelerometer reach responses of a plurality of preset target input accelerations in a second frequency band, and respectively obtaining a plurality of output signals; performing nonlinear coefficient identification according to the plurality of preset target input accelerations and the plurality of output signals; wherein the frequency of the at least one input acceleration is within a first frequency band. According to the invention, a nonlinear identification scheme of the under-damping accelerometer is provided.

Description

Technical Field

[0001] The present application belongs to the field of accelerometers, and more specifically, to a method and device for identifying nonlinear coefficients of an accelerometer. Background Art

[0002] In inertial navigation applications, the nonlinearity of the accelerometer is very important. The greater the nonlinearity, the greater the degree to which the accelerometer output deviates from the true acceleration input. When there is vibration acceleration input, the nonlinear coefficient of the accelerometer and the vibration acceleration work together to cause a DC offset in the accelerometer output, namely, the vibration rectification error (VRE), which is very unfavorable for the precise measurement of acceleration and seriously affects the accuracy of inertial navigation. Therefore, in order to compensate for the nonlinearity later, it is very important to identify the nonlinear coefficient of the accelerometer.

[0003] There are many methods for identifying the nonlinear coefficient of accelerometers. For example, the nonlinear coefficient of accelerometers can be identified by using the harmonic analysis method through multi-point tumbling of the dividing head in the gravity field. However, the maximum input acceleration is only one gravity acceleration ( g ), it is not possible to adjust the range to more than 1 g The nonlinear coefficient of the accelerometer is identified; the centrifuge is also often used to identify the nonlinear coefficient of the accelerometer. The angular velocity of the rotating turntable is used to generate a standard centripetal acceleration. By adjusting the angular velocity, the input acceleration can be flexibly adjusted to identify the nonlinear coefficient of the accelerometer. However, the disadvantage is also obvious. The single time cost is high. It may even take several hours to conduct a centrifuge experiment.

[0004] Identifying the nonlinear coefficient through a vibration table is a relatively mature solution, which takes into account the advantages of fast measurement speed, high accuracy and economy. However, for a high-precision vibration table, the mass of the moving parts and the test sensor needs to match, which means that the mass of the moving parts cannot be too small. Under the same thrust, the maximum output acceleration that can be achieved is insufficient, which affects the nonlinear identification of a large-range accelerometer. Therefore, it is of great significance to develop and improve the method of identifying the nonlinear coefficient of the vibration table. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of the present application is to provide a method and device for identifying the nonlinear coefficient of an accelerometer, aiming to solve the problem that the output acceleration of the excitation device used for the nonlinear identification of the existing accelerometer is insufficient, or the accuracy cannot be guaranteed when the input acceleration of the excitation device is large, thereby failing to achieve high-precision nonlinear identification of the accelerometer.

[0006] To achieve the above objectives, in a first aspect, the present application provides a method for identifying nonlinear coefficients of an accelerometer, which is applicable to an underdamped accelerometer, comprising: Acquire the amplitude-frequency response information of the accelerometer; the amplitude-frequency response information includes: gain information at different frequency points; the gain is the ratio of the accelerometer response corresponding to the acceleration input at the corresponding frequency point to the accelerometer response corresponding to the acceleration input of the same amplitude constant value; wherein, the gain of the underdamped accelerometer is greater than 1 in the first frequency range, and there is a maximum gain at the resonant frequency of the accelerometer, and the gain is flat and close to 1 in the second frequency range; In combination with the amplitude-frequency response information, the frequencies and amplitudes of the multiple input accelerations are set so that the multiple responses of the accelerometer reach the responses of the multiple preset target input accelerations within the second frequency band, and the multiple output signals of the accelerometer at the multiple responses are respectively obtained; The nonlinear coefficient of the accelerometer is identified according to the multiple preset target input accelerations and the multiple output signals; wherein the frequency of at least one input acceleration among the multiple input accelerations corresponding to the multiple preset target input accelerations is within the first frequency range.

[0007] It can be understood that since the gain in the first frequency band is greater than 1, the accelerometer response to be achieved by a large-amplitude target input acceleration can be achieved by utilizing a small-amplitude input acceleration with a frequency in the first frequency band, thereby obtaining an output signal corresponding to the preset target input acceleration and realizing the identification of the nonlinear coefficient of the accelerometer.

[0008] Furthermore, the present application utilizes a small-amplitude input acceleration of a high-precision excitation device to realize the identification of the nonlinear coefficient of the accelerometer, which can greatly ensure the accuracy of the nonlinear coefficient identification of the accelerometer and improve the reliability of the nonlinear identification of the accelerometer.

[0009] Furthermore, corresponding to a large-range accelerometer, facing the current excitation device with limited input acceleration amplitude, it is possible to realize the nonlinear coefficient identification of a large-range accelerometer by a small-thrust and high-precision excitation device through the solution provided in this application, which can solve the current technical difficulties and has broad application prospects.

[0010] In one possible implementation, when the accelerometer is an open-loop accelerometer, the accelerometer response refers to the displacement of the proof mass in the accelerometer; when the accelerometer is a closed-loop accelerometer, the accelerometer response refers to the feedback signal acting on the proof mass in the accelerometer to balance it at zero position.

[0011] In a possible implementation manner, when the frequency of the input acceleration is within a first frequency range, the amplitude of the input acceleration is smaller than the amplitude of the corresponding preset target input acceleration.

[0012] In a possible implementation, when the frequency of the input acceleration is within the first frequency range, the frequency and amplitude of the input acceleration are set in combination with the amplitude-frequency response information, including: determining a magnitude of a preset target input acceleration; Setting an input acceleration amplitude smaller than a preset target input acceleration amplitude, determining a ratio of the preset target input acceleration amplitude to the set input acceleration amplitude, searching for a frequency point whose gain is equal to the ratio in the first frequency range, and setting the frequency point as the frequency of the input acceleration; or Setting a frequency of input acceleration in the first frequency range, determining a gain of the corresponding frequency in the first frequency range based on the amplitude-frequency response information, and setting a value obtained by dividing the amplitude of the preset target input acceleration by the gain as the amplitude of the input acceleration; The ratio of the preset target input acceleration amplitude to the set input acceleration amplitude is used as the ratio of the accelerometer response corresponding to the preset target input acceleration amplitude and the set input acceleration amplitude in the second frequency range.

[0013] In one possible implementation, when the maximum output acceleration amplitude of the excitation device used to provide the input acceleration is smaller than the range of the accelerometer, if the amplitude of the maximum input acceleration that the excitation device can provide at the resonant frequency of the accelerometer is not less than the ratio of the accelerometer range to the maximum gain value, then the multiple input accelerations can all be provided by the excitation device.

[0014] In a possible implementation, the amplitude of the input acceleration required to obtain the amplitude-frequency response information of the accelerometer is smaller than the range of the accelerometer; and / or the amplitude of the input acceleration required to obtain the amplitude-frequency response information of the accelerometer is fixed.

[0015] It is understandable that when the nonlinear coefficient of the accelerometer is identified, it is necessary to obtain the output signal corresponding to the response of the accelerometer when the input acceleration is within the accelerometer range and the range. Therefore, when the scheme of the present application is used for identification, if the preset target input acceleration amplitude is small, an acceleration with equal or close corresponding amplitude can be directly input in the second frequency band to obtain the corresponding output signal, or an acceleration with a smaller corresponding amplitude can be input in the first frequency band to obtain the corresponding output signal; if the preset target input acceleration amplitude is large, an acceleration with a smaller corresponding amplitude can be input in the first frequency band to obtain the corresponding output signal.

[0016] In a second aspect, the present application provides an accelerometer nonlinear coefficient identification device, which is applicable to an underdamped accelerometer and includes: an excitation unit and a data processing unit; The data processing unit is used to obtain the amplitude-frequency response information of the accelerometer; the amplitude-frequency response information includes: gain information at different frequency points; the gain is the ratio of the accelerometer response corresponding to the acceleration input at the corresponding frequency point to the accelerometer response corresponding to the acceleration input of the same amplitude constant value; wherein, the gain of the underdamped accelerometer is greater than 1 in the first frequency range, and there is a maximum gain at the resonant frequency of the accelerometer, and the gain is flat and close to 1 in the second frequency range; The data processing unit is used to set the frequencies and amplitudes of multiple input accelerations in combination with the amplitude-frequency response information, so that the multiple responses of the accelerometer reach the responses of multiple preset target input accelerations within the second frequency range; wherein the frequency of at least one input acceleration among the multiple input accelerations corresponding to the multiple preset target input accelerations is within the first frequency range; The excitation unit is used to provide the plurality of input accelerations to the accelerometer; The data processing unit is used to respectively obtain multiple output signals of the accelerometers corresponding to the multiple responses; and to perform nonlinear coefficient identification on the accelerometers according to the multiple preset target input accelerations and the multiple output signals.

[0017] In a possible implementation, the excitation unit is further used to provide the accelerometer with a test acceleration input for obtaining the amplitude-frequency response information; the amplitude of the test acceleration input is smaller than the range of the accelerometer; and / or The amplitude of the test acceleration input is fixed, and the frequency varies between the first frequency range and the second frequency range.

[0018] In a possible implementation, when the frequency of the input acceleration is within a first frequency range, the amplitude of the input acceleration provided by the excitation unit is smaller than the amplitude of the corresponding preset target input acceleration.

[0019] In one possible implementation, when the data processing unit needs to set the input acceleration within the first frequency band, the data processing unit determines the amplitude of a preset target input acceleration; sets an input acceleration amplitude that is smaller than the preset target input acceleration amplitude, determines the ratio of the preset target input acceleration amplitude to the set input acceleration amplitude, searches for a frequency point whose gain is equal to the ratio within the first frequency band, and sets the frequency point as the frequency of the input acceleration; or sets an input acceleration frequency within the first frequency band, determines the gain of the corresponding frequency within the first frequency band based on the amplitude-frequency response information, and sets the value obtained by dividing the amplitude of the preset target input acceleration by the gain as the amplitude of the input acceleration; wherein the ratio of the preset target input acceleration amplitude to the set input acceleration amplitude is used as the ratio of the accelerometer response corresponding to the preset target input acceleration amplitude and the set input acceleration amplitude within the second frequency band.

[0020] In one possible implementation, when the maximum output acceleration amplitude of the excitation unit is smaller than the measuring range of the accelerometer, if the amplitude of the maximum input acceleration that the excitation unit can provide at the resonant frequency of the accelerometer is not smaller than the ratio of the measuring range of the accelerometer to the maximum gain value, then the multiple input accelerations can all be provided by the excitation unit.

[0021] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art: The present application provides a method and device for identifying the nonlinear coefficient of an accelerometer, which utilizes a small-amplitude input acceleration with a frequency within a first frequency band to realize the accelerometer response to be realized by a large-amplitude target input acceleration, thereby obtaining an output signal corresponding to a preset target input acceleration, and realizing the identification of the nonlinear coefficient of the accelerometer. Therefore, the present application utilizes a small-amplitude input acceleration of a high-precision excitation device to realize the identification of the nonlinear coefficient of the accelerometer, which can greatly ensure the accuracy of the identification of the nonlinear coefficient of the accelerometer and improve the reliability of the nonlinear identification of the accelerometer. For a large-range accelerometer, in the face of the current excitation device with limited input acceleration amplitude, the scheme provided by the present application can realize the identification of the nonlinear coefficient of a large-range accelerometer by a high-precision small-thrust excitation device, which can solve the current technical difficulties and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a flow chart of a method for identifying nonlinear coefficients of an accelerometer provided in an embodiment of the present application; Figure 2 It is a schematic diagram of the sensitive axis of the accelerometer and the main vibration direction of the vibration table provided in the embodiment of the present application; Figure 3It is a schematic diagram of the amplitude-frequency response of the underdamped second-order system of the accelerometer and the displacement amplification of the mass block provided in the embodiment of the present application; Figure 4 is a vibration rectification error diagram after displacement amplification of the accelerometer mass block provided in an embodiment of the present application; Figure 5 It is a structural diagram of an accelerometer nonlinear coefficient identification device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0024] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0025] In view of the problem of using an excitation device (such as a vibration table) to identify the nonlinear coefficient of an accelerometer, this application provides a method for identifying the nonlinearity of an accelerometer using underdamping characteristics. In the process of identifying the nonlinear coefficient of an accelerometer, the purpose is to solve the problem that the thrust of a high-precision excitation device is insufficient and cannot excite the nonlinear response of the accelerometer under large input acceleration.

[0026] Figure 1 The flowchart of the accelerometer nonlinear identification method provided in the embodiment of the present application is as follows: Figure 1 As shown, the following steps are included: Step S101, obtaining amplitude-frequency response information of the accelerometer; the amplitude-frequency response information includes: gain information at different frequency points; the gain is the ratio of the accelerometer response corresponding to the acceleration input at the corresponding frequency point to the accelerometer response corresponding to the acceleration input of the same amplitude constant; wherein, the gain of the underdamped accelerometer is greater than 1 in the first frequency range, and there is a maximum gain at the resonant frequency of the accelerometer, and the gain is flat and close to 1 in the second frequency range.

[0027] Among them, the close to 1 mentioned in the embodiments of the present application means that the absolute value of the difference with 1 is within 5%; greater than 1 means that the difference with 1 exceeds 5%.

[0028] It should be noted that when the accelerometer is an open-loop accelerometer, the accelerometer response refers to the displacement of the proof mass in the accelerometer; when the accelerometer is a closed-loop accelerometer, the accelerometer response refers to the feedback signal acting on the proof mass in the accelerometer to balance it at the zero position.

[0029] Further, when the frequency of the input acceleration is within the first frequency range, the amplitude of the input acceleration is smaller than the amplitude of the corresponding preset target input acceleration.

[0030] Step S102, combining the amplitude-frequency response information, setting the frequencies and amplitudes of multiple input accelerations so that multiple responses of the accelerometer reach responses of multiple preset target input accelerations within the second frequency band, and respectively obtaining multiple output signals of the accelerometer at the multiple responses.

[0031] It can be understood by those skilled in the art that, within the second frequency band, the larger the amplitude of the input acceleration, the higher the corresponding accelerometer response. And the ratio of the input acceleration amplitudes is equal to the ratio of the accelerometer responses, which is a linear relationship. It should be noted that the nonlinear coefficient that needs to be identified in this application corresponds to the second-order nonlinear relationship between the accelerometer input signal and the accelerometer output signal. Therefore, for multiple set input accelerations that respond to multiple preset target input accelerations within the second frequency band, the input signal can be considered to be the preset target input acceleration.

[0032] It can be understood that, referring to the above explanation, when the amplitude of the set input acceleration is relatively small and smaller than the preset target input acceleration amplitude, the response of the preset target input acceleration in the second frequency band cannot be determined from the above amplitude-frequency response information. At this time, the response corresponding to the small-amplitude acceleration input in the amplitude-frequency response information can be referred to, and the corresponding response can be amplified in combination with the multiple relationship between the preset target input acceleration amplitude and the small-amplitude acceleration amplitude to obtain the response corresponding to the preset target input acceleration.

[0033] To facilitate subsequent calculations, the response of the input acceleration in the second frequency band does not need to be directly calculated, and the calculation process here can be saved through the above linear relationship. For details, please refer to the relevant description in the following step S103.

[0034] Step S103, performing nonlinear coefficient identification on the accelerometer according to the multiple preset target input accelerations and the multiple output signals; wherein the frequency of at least one input acceleration among the multiple input accelerations corresponding to the multiple preset target input accelerations is within the first frequency range.

[0035] In one example, when the frequency of the input acceleration is within the first frequency range, the frequency and amplitude of the input acceleration are set in combination with the amplitude-frequency response information, including: determining a magnitude of a preset target input acceleration; Setting an input acceleration amplitude smaller than a preset target input acceleration amplitude, determining a ratio of the preset target input acceleration amplitude to the set input acceleration amplitude, searching for a frequency point whose gain is equal to the ratio in the first frequency range, and setting the frequency point as the frequency of the input acceleration; or Setting a frequency of input acceleration in the first frequency range, determining a gain of the corresponding frequency in the first frequency range based on the amplitude-frequency response information, and setting a value obtained by dividing the amplitude of the preset target input acceleration by the gain as the amplitude of the input acceleration; The ratio of the preset target input acceleration amplitude to the set input acceleration amplitude is used as the ratio of the accelerometer response corresponding to the preset target input acceleration amplitude and the set input acceleration amplitude in the second frequency range.

[0036] Further, it can be understood that when the maximum output acceleration amplitude of the excitation device used to provide input acceleration is smaller than the range of the accelerometer, if the amplitude of the maximum input acceleration that can be provided by the excitation device at the resonant frequency of the accelerometer is not less than the ratio of the accelerometer range to the maximum gain value mentioned in the above step S101, then the multiple input accelerations in the embodiments of the present application can all be provided by the above excitation device.

[0037] Further, for example, the amplitude of the input acceleration required to obtain the amplitude-frequency response information of the accelerometer is smaller than the range of the accelerometer; and / or the amplitude of the input acceleration required to obtain the amplitude-frequency response information of the accelerometer is fixed.

[0038] In a more specific embodiment, taking the excitation device as a vibration table as an example, to achieve the above purpose, this embodiment provides a method for identifying the nonlinearity of a large-range accelerometer using underdamping characteristics, including: Figure 2 As shown, the accelerometer is installed on a horizontal slide table of a horizontal vibration table, and the sensitive axis is parallel to the main vibration direction of the vibration table (it should be noted that the horizontal vibration table is only used to explain an embodiment of the present application. The method of installing the accelerometer on a vertical vibration table along the sensitive axis and testing the nonlinear coefficient of the accelerometer is also included in the content of the present application). In this state, a series of vibration frequency points are set, and the vibration frequency points should include the resonant frequency of the mechanical sensitive structure of the accelerometer; the resonant frequency is the frequency point corresponding to the maximum output of the accelerometer when the accelerometer is input with the same amplitude acceleration; the same amplitude acceleration input means that the vibration table output acceleration amplitudes at the series of vibration frequency points are all set to the same; if the accelerometer output is fully biased when the same amplitude acceleration input is set, the vibration table output acceleration amplitude at the resonant frequency point should be reasonably lowered.

[0039] According to the output of each frequency point of the accelerometer divided by the acceleration input at each set frequency point, the amplitude-frequency response of the accelerometer is normalized to obtain the gain of the accelerometer mechanical structure response at each set frequency point.

[0040] Figure 2A schematic diagram of the sensitive axis of the accelerometer and the main vibration direction of the vibration table provided in the embodiment of the present application. As shown in the figure, the accelerometer to be tested is installed on the table top of the vibration table, and the sensitive axis is parallel to the main vibration direction of the vibration table; in the present application, the sensitive axis of the accelerometer can be the sensitive axis of a single-axis accelerometer, or the sensitive axis of each axis in a three-axis accelerometer, such as the X-axis is parallel to the main vibration direction, and the same is true for the Y-axis and the Z-axis; the main vibration direction of the vibration table is the main direction of the electromagnetic force output by the vibration table; the electromagnetic force acts on the horizontal slide of the vibration table and the accelerometer fixed thereon, and according to Newton's second law, the accelerometer test mass will generate acceleration.

[0041] For example, the response gain of an accelerometer can be either the displacement magnification factor of the mechanical structure proof mass in an open-loop accelerometer or the magnification factor of the feedback output signal in a closed-loop accelerometer; the displacement magnification factor represents the ratio of the displacement of the mechanical structure proof mass of the accelerometer at the corresponding frequency point to the displacement at the same acceleration input at direct current (DC), characterizing the amplitude-frequency characteristics of the acceleration-displacement relationship in the accelerometer; in the present application, unless otherwise specified, the displacement magnification factor of the open-loop accelerometer will be used as the response gain to explain the present application.

[0042] Furthermore, the amplitude-frequency characteristic of the acceleration-displacement relationship in the accelerometer must be an underdamped characteristic; the underdamped characteristic is that the amplitude-frequency response curve of the accelerometer has a resonance peak at the resonance frequency point, which can be seen in Figure 3 shown.

[0043] Figure 3 It is a schematic diagram of the amplitude-frequency response of the underdamped second-order system of the accelerometer provided in the embodiment of the present application and the displacement amplification of the mass block. Figure 3 The scatter data and fitting curve of displacement magnification are included in the figure. The fitting curve can be obtained by fitting according to formula (1): (1) in, represents the displacement magnification, ω 0. ω They represent the inherent angular frequency of the accelerometer and the angular frequency (i.e. frequency) of the external input acceleration signal, respectively. Q It represents the quality factor, which characterizes the damping of the second-order accelerometer system. Its value corresponds to the angular frequency on the amplitude-frequency response curve. ω The highest point at 0 is the maximum gain, which means the displacement amplification factor is the largest.

[0044] When the angular frequency of the input acceleration signal is much smaller than the natural angular frequency of the accelerometer, that is, When the accelerometer checks the displacement of the mass With input acceleration The relationship can be expressed as: (2) Displacement magnification is a constant, accordingly, see Figure 3 As shown, in the low frequency band, the displacement of the test mass corresponds to the amplitude of the input acceleration, and the displacement magnification factor in this low frequency band changes flatly, close to 1; close to 1 here means that the absolute value of the difference from 1 is within 5%. In this low frequency band, the large displacement of the accelerometer test mass can only be achieved by a large acceleration input amplitude; see Figure 3 , in the high frequency band of the amplitude-frequency curve of the underdamped second-order system (the displacement magnification factor does not change flatly, and the difference from 1 exceeds 5%), formula (2) is no longer valid. The displacement magnification factor is related to the frequency. If the inspection quality is to achieve the same large displacement as in the low frequency band, only a smaller input acceleration amplitude is required. Table 1 lists the range of a certain type of ±30 g Parameter settings for full-scale nonlinear identification of the accelerometer, where X represents the displacement of the test mass, that is, the displacement of the test mass is the same under the three parameter settings.

[0045] It should be noted that Figure 3 The low frequency band in corresponds to the second frequency band mentioned in step S101, and the high frequency band corresponds to the first frequency band mentioned in step S101.

[0046] Table 1 Parameter settings for linear identification

[0047] Furthermore, the underdamped second-order system is expressed as Q For a second-order system when is greater than 0.5, further, in this application, Q The conditions to be met are: (3) in, A max ( ω 0) represents the maximum input acceleration amplitude that the vibration table can provide at the resonant frequency of the accelerometer. a FS Indicates the range of the accelerometer to be tested, that is, Q When the value satisfies formula (3), there is always a corresponding frequency and input acceleration combination in the setting parameters of the vibration table, so that the equivalent acceleration is greater than or equal to the range of the required test accelerometer; at this time, the above-mentioned high-precision and low-thrust vibration table can provide all the input accelerations required for the above-mentioned test accelerometer, because it can achieve the maximum response of the accelerometer greater than or equal to the required response under the full range of the accelerometer.

[0048] For high-precision vibration tables, the moving parts and the test sensor mass need to match. Therefore, for the calibration of the displacement nonlinearity of a large-range accelerometer, the high-precision vibration table usually shows insufficient thrust; the vibration table thrust corresponds to the acceleration acting on the accelerometer; further, to the displacement of the accelerometer mechanical structure inspection mass.

[0049] Furthermore, the displacement of the mechanical structure inspection mass can utilize the amplitude-frequency characteristics of the acceleration-displacement relationship in the accelerometer to amplify the displacement at the corresponding frequency point by setting a suitable acceleration amplitude; the amplified displacement is the same as the target displacement when the DC acceleration is input.

[0050] The nonlinear coefficient of the accelerometer can be obtained through a vibration rectification error; the vibration rectification error is generated by the combined action of a vibration acceleration signal and a second-order nonlinearity, and when there is a vibration acceleration input, it manifests as a DC offset in the accelerometer output.

[0051] Figure 4 The vibration rectification error diagram of the accelerometer inspection mass displacement amplification provided in the embodiment of the present application, wherein Vib.ON indicates that the vibration table continuously outputs the vibration signal, Vib.OFF indicates that the vibration table stops outputting the vibration signal, and VRE1 indicates the vibration rectification error of the accelerometer during the vibration acceleration input. In this example, the vibration table is set with two frequency points and corresponding amplitude points, the two frequency points are close to the accelerometer resonant frequency, and the amplitude points meet the displacement of the accelerometer mechanical structure inspection mass at the corresponding frequency points and the target acceleration at the DC (here 25 g with 30 g ) input. See Table 2 for specific parameter settings.

[0052] Table 2. Vibration test setting parameters for underdamped second-order system

[0053] The nonlinear coefficient is identified by calculating the vibration rectification error. The vibration rectification error is generated by the interaction of the second-order nonlinearity of the accelerometer and the vibration acceleration, and is manifested as the offset of the accelerometer zero bias when the vibration is input. The model equation containing the second-order nonlinear coefficient of the accelerometer is assumed to be: (4) in, y Represents the accelerometer output in units of g , input acceleration , K 1. K 2. K 0 refers to the accelerometer scale factor, second-order nonlinear coefficient and zero bias, G is the amplitude of the vibration acceleration input, is the angular frequency of the vibration acceleration input.

[0054] Then the zero bias offset of the accelerometer when vibration input occurs can be obtained: for: (5) The second-order nonlinear coefficient of the accelerometer can be calculated by formula (5).

[0055] It is understandable that when the accuracy of the excitation device for nonlinear identification of the accelerometer is higher (the smaller the maximum thrust output), the corresponding identification accuracy will also be higher. Therefore, the solution provided in the embodiment of the present application is not only applicable to the nonlinear identification of a large-range accelerometer by an excitation device with insufficient thrust, but also applicable to the nonlinear identification of any adapted accelerometer by an excitation device with small thrust output, so as to achieve high-precision nonlinear identification of the accelerometer.

[0056] In some embodiments, the present application also provides an accelerometer nonlinear coefficient identification device, such as Figure 5 As shown, it includes: an excitation unit 510 and a data processing unit 520; The data processing unit 520 is used to obtain the amplitude-frequency response information of the accelerometer; the amplitude-frequency response information includes: gain information at different frequency points; the gain is the ratio of the accelerometer response corresponding to the acceleration input at the corresponding frequency point to the accelerometer response corresponding to the acceleration input of the same amplitude constant value; wherein, the gain of the underdamped accelerometer is greater than 1 in the first frequency range, and there is a maximum gain at the resonant frequency of the accelerometer, and the gain is flat and close to 1 in the second frequency range; The data processing unit 520 is used to set the frequencies and amplitudes of the multiple input accelerations in combination with the amplitude-frequency response information, so that the multiple responses of the accelerometer reach the responses of the multiple preset target input accelerations within the second frequency range; wherein the frequency of at least one input acceleration among the multiple input accelerations corresponding to the multiple preset target input accelerations is within the first frequency range; An excitation unit 510, configured to provide the plurality of input accelerations to the accelerometer; The data processing unit 520 is used to respectively obtain a plurality of output signals of the accelerometers at the plurality of responses; and to perform nonlinear coefficient identification on the accelerometer according to the plurality of preset target input accelerations and the plurality of output signals.

[0057] The excitation unit 510 is also used to provide the accelerometer with a test acceleration input for obtaining the amplitude-frequency response information; the amplitude of the test acceleration input is less than the range of the accelerometer; and / or the amplitude of the test acceleration input is fixed and the frequency varies between the first frequency range and the second frequency range.

[0058] When the frequency of the input acceleration is within the first frequency range, the amplitude of the input acceleration provided by the excitation unit 510 is smaller than the amplitude of the corresponding preset target input acceleration.

[0059] When the data processing unit 520 needs to set the input acceleration within the first frequency band, the data processing unit 520 determines the amplitude of the preset target input acceleration; sets an input acceleration amplitude that is smaller than the preset target input acceleration amplitude, determines the ratio of the preset target input acceleration amplitude to the set input acceleration amplitude, searches for a frequency point whose gain is equal to the ratio within the first frequency band, and sets the frequency point as the frequency of the input acceleration; or sets an input acceleration frequency within the first frequency band, determines the gain of the corresponding frequency within the first frequency band based on the amplitude-frequency response information, and sets the value obtained by dividing the amplitude of the preset target input acceleration by the gain as the amplitude of the input acceleration; wherein the ratio of the preset target input acceleration amplitude to the set input acceleration amplitude is used as the ratio of the accelerometer response corresponding to the preset target input acceleration amplitude and the set input acceleration amplitude within the second frequency band.

[0060] When the maximum output acceleration amplitude of the excitation unit 510 is smaller than the measuring range of the accelerometer, if the amplitude of the maximum input acceleration that the excitation unit can provide at the resonant frequency of the accelerometer is not smaller than the ratio of the measuring range of the accelerometer to the maximum gain value, then the multiple input accelerations can all be provided by the excitation unit.

[0061] It should be noted that the excitation unit 510 can be implemented by any device, equipment or component that can provide variable-frequency acceleration input to the accelerometer.

[0062] The data processing unit 520 can be implemented by any unit, module, circuit or device with data processing function. In one example, it can be implemented by a processor, which can be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor can be a microprocessor or any conventional processor.

[0063] In addition, the method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0064] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence 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 "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0065] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0066] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0067] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0068] 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 who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for identifying nonlinear coefficients of an accelerometer, the method being applicable to an underdamped accelerometer, characterized in that: include: Obtain the amplitude-frequency response information of the accelerometer; The amplitude-frequency response information includes: gain information at different frequency points; the gain is the ratio of the accelerometer response corresponding to the acceleration input at the corresponding frequency point to the accelerometer response corresponding to the acceleration input of the same amplitude constant value; wherein, the gain of the underdamped accelerometer is greater than 1 in the first frequency range, and there is a maximum gain at the accelerometer resonant frequency, and the gain is flat and close to 1 in the second frequency range; In combination with the amplitude-frequency response information, the frequencies and amplitudes of the multiple input accelerations are set so that the multiple responses of the accelerometer reach the responses of the multiple preset target input accelerations within the second frequency range, and the multiple output signals of the accelerometer at the multiple responses are respectively obtained; wherein the frequency of at least one of the multiple input accelerations corresponding to the multiple preset target input accelerations is within the first frequency range; Nonlinear coefficient identification is performed on the accelerometer according to the plurality of preset target input accelerations and the plurality of output signals.

2. The method according to claim 1, characterized in that When the accelerometer is an open-loop accelerometer, the accelerometer response refers to the displacement of the proof mass in the accelerometer; when the accelerometer is a closed-loop accelerometer, the accelerometer response refers to the feedback signal acting on the proof mass in the accelerometer to balance it at the zero position.

3. The method according to claim 1, characterized in that When the frequency of the input acceleration is within the first frequency range, the amplitude of the input acceleration is smaller than the amplitude of the corresponding preset target input acceleration.

4. The method according to claim 1, characterized in that: When the frequency of the input acceleration is within the first frequency range, the frequency and amplitude of the input acceleration are set in combination with the amplitude-frequency response information, including: determining a magnitude of a preset target input acceleration; Setting an input acceleration amplitude smaller than a preset target input acceleration amplitude, determining a ratio of the preset target input acceleration amplitude to the set input acceleration amplitude, searching for a frequency point whose gain is equal to the ratio in the first frequency range, and setting the frequency point as the frequency of the input acceleration; or Setting a frequency of input acceleration in the first frequency range, determining a gain of the corresponding frequency in the first frequency range based on the amplitude-frequency response information, and setting a value obtained by dividing the amplitude of the preset target input acceleration by the gain as the amplitude of the input acceleration; The ratio of the preset target input acceleration amplitude to the set input acceleration amplitude is used as the ratio of the accelerometer response corresponding to the preset target input acceleration amplitude and the set input acceleration amplitude in the second frequency range.

5. The method according to any one of claims 1 to 4, characterized in that: When the maximum output acceleration amplitude of the excitation device used to provide the input acceleration is smaller than the measuring range of the accelerometer, if the amplitude of the maximum input acceleration that can be provided by the excitation device at the resonant frequency of the accelerometer is not less than the ratio of the measuring range of the accelerometer to the maximum gain value, then the multiple input accelerations can all be provided by the excitation device.

6. An accelerometer nonlinear coefficient identification device, the device is suitable for underdamped accelerometers, characterized in that: include: Excitation unit and data processing unit; The data processing unit is used to obtain the amplitude-frequency response information of the accelerometer; The amplitude-frequency response information includes: gain information at different frequency points; the gain is the ratio of the accelerometer response corresponding to the acceleration input at the corresponding frequency point to the accelerometer response corresponding to the acceleration input of the same amplitude constant value; wherein, the gain of the underdamped accelerometer is greater than 1 in the first frequency range, and there is a maximum gain at the accelerometer resonant frequency, and the gain is flat and close to 1 in the second frequency range; The data processing unit is used to set the frequencies and amplitudes of the multiple input accelerations in combination with the amplitude-frequency response information, so that the multiple responses of the accelerometer reach the responses of the multiple preset target input accelerations within the second frequency range; wherein the frequency of at least one input acceleration among the multiple input accelerations corresponding to the multiple preset target input accelerations is within the first frequency range; The excitation unit is used to provide the plurality of input accelerations to the accelerometer; The data processing unit is used to respectively obtain multiple output signals of the accelerometers corresponding to the multiple responses; and to perform nonlinear coefficient identification on the accelerometers according to the multiple preset target input accelerations and the multiple output signals.

7. The device according to claim 6, characterized in that The excitation unit is further used to provide the accelerometer with a test acceleration input for obtaining the amplitude-frequency response information; the amplitude of the test acceleration input is smaller than the range of the accelerometer; and / or The amplitude of the test acceleration input is fixed, and the frequency varies between the first frequency range and the second frequency range.

8. The device according to claim 6, characterized in that When the frequency of the input acceleration is within the first frequency range, the amplitude of the input acceleration provided by the excitation unit is smaller than the amplitude of the corresponding preset target input acceleration.

9. The device according to claim 6, characterized in that When the data processing unit needs to set the input acceleration within the first frequency band, the data processing unit determines the amplitude of the preset target input acceleration; An input acceleration amplitude smaller than a preset target input acceleration amplitude is set, a ratio of the preset target input acceleration amplitude to the set input acceleration amplitude is determined, a frequency point whose gain is equal to the ratio is found in the first frequency range, and the frequency point is set as the frequency of the input acceleration; or an input acceleration frequency is set in the first frequency range, a gain of the corresponding frequency in the first frequency range is determined based on the amplitude-frequency response information, and a value obtained by dividing the amplitude of the preset target input acceleration by the gain is set as the amplitude of the input acceleration; wherein the ratio of the preset target input acceleration amplitude to the set input acceleration amplitude is used as the ratio of the accelerometer response corresponding to the preset target input acceleration amplitude and the set input acceleration amplitude in the second frequency range.

10. The device according to any one of claims 6 to 9, characterized in that When the maximum output acceleration amplitude of the excitation unit is smaller than the measuring range of the accelerometer, if the amplitude of the maximum input acceleration that the excitation unit can provide at the resonant frequency of the accelerometer is not smaller than the ratio of the measuring range of the accelerometer to the maximum gain value, then the multiple input accelerations can all be provided by the excitation unit.

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