CN113466492B - Device and method for measuring accelerometer model parameter magnetic vector sensitivity - Google Patents
Device and method for measuring accelerometer model parameter magnetic vector sensitivity Download PDFInfo
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Abstract
The invention discloses a device and a method for measuring the sensitivity of a magnetic vector of a model parameter of an accelerometer, wherein the device comprises the following steps: the acceleration generating module is fixedly connected with the magnetic field generating module and provides variable and quantifiable acceleration input for the accelerometer; the magnetic field generation module provides a variable and stable magnetic field environment for the accelerometer; when the acceleration generating module is used, the magnetic field generating module has the same pose change as the acceleration generating module, so that the magnetic field environment of the accelerometer to be measured is unchanged when the input acceleration is changed. The invention ensures that the angle relation between the sensitive axis of the accelerometer and the magnetic field direction is unchanged in the detection process by keeping the space angle relation between the magnetic vector direction generated by the magnetic field generating device and the accelerometer testing device unchanged; therefore, when the input acceleration along each axis of the accelerometer is changed, the magnetic field environment where each axis of the accelerometer is located is not changed, and errors caused by the fact that the direction of the accelerometer relative to a magnetic field is changed are avoided.
Description
Technical Field
The invention belongs to the technical field of accelerometer testing, and particularly relates to a device and a method for measuring the sensitivity of a magnetic vector of a parameter of an accelerometer model.
Background
The accelerometer is an inertial instrument for detecting the motion acceleration of an object, and is widely applied to the aspects of inertial navigation guidance, microseismic measurement, precision gravity measurement and the like. The magnetic sensitivity of the accelerometer represents the physical quantity of the influence of an external environment magnetic field on the accelerometer, and is used for representing the influence of unit magnetic field strength on the output of the accelerometer, which can directly influence the authenticity of a detection signal of the accelerometer. When the accelerometer is applied, if the magnetic sensitivity of the accelerometer is high, the target signal may be submerged by the output signal caused by the change of the magnetic field, or the output change caused by the change of the magnetic field may be mistaken for the target signal to be detected, so that the detection is abnormal. This requires that the magnetic sensitivity of the accelerometer be detected in order to, in use, in combination with the ambient magnetic field, subtract the error signal caused by the magnetic field and thereby improve the performance of the accelerometer.
The current method for testing the magnetic sensitivity of the accelerometer is a method for testing the magnetic sensitivity of an analog vibration and impact sensor, the sensor is placed in a uniform magnetic field, the maximum output value of the sensor in the magnetic field is found by fixing the magnetic field to rotate the sensor or fixing the sensor to rotate the magnetic field, and the ratio of the maximum output value to the current magnetic induction intensity is used as the magnetic sensitivity of the sensor. This is based primarily on improvements made in or on GB/T13823.4 or ISO 5347-19.
The existing method has the defects that firstly, the existing method can only measure the maximum response of the total output of the accelerometer about the magnetic field, although the test result of the method can provide guidance for the magnetic shielding requirement of the accelerometer, the model parameters of the accelerometer are not separated, for example, in the application of a rotating accelerometer gravity gradiometer, the respective magnetic field responses of the zero offset and the scale factor of the accelerometer need to be discussed respectively, but in the separation process, the direction of the accelerometer relative to the geomagnetic field is also changed continuously, and the geomagnetic field can influence the detection result; secondly, because the magnetic field is a directional vector, the existing method does not consider that the magnetic sensitivity of the accelerometer changes when the angular relationship between the accelerometer and the direction of the magnetic field changes.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method for measuring the magnetic vector sensitivity of the accelerometer model parameters, which aims to separate the magnetic vector sensitivity of the accelerometer model parameters and solve the problem of low separation precision caused by the interference of factors such as accelerometer low-frequency drift, environmental noise, geomagnetic field relative to the direction change of the accelerometer and the like in the prior art on the test result.
In order to achieve the above object, the present invention provides an apparatus for measuring sensitivity of magnetic vector of accelerometer model parameters, comprising: the acceleration generation module is used for providing variable and quantifiable acceleration input for the accelerometer; the magnetic field generation module is used for providing a variable and stable magnetic field environment for the accelerometer; when the acceleration generating module is used, the magnetic field generating module has the same pose change as the acceleration generating module, so that the magnetic field environment of the accelerometer to be tested arranged in the magnetic field generating module is unchanged when the input acceleration is changed.
Further, the acceleration generating module and the magnetic field generating module are fixedly connected by screws.
The invention also provides a method for measuring the sensitivity of the magnetic vector of the accelerometer model parameter based on the device, which comprises the following steps:
s1: generating an alternating magnetic field with a first amplitude and a first frequency by a magnetic field generating device, and collecting the output of an accelerometer as a first output;
by changing the amplitude of the magnetic field, the magnetic field generating device generates an alternating magnetic field with a second amplitude and a first frequency, and the output of the accelerometer is collected as a second output;
Repeating the steps M times and obtaining accelerometer outputs under M groups of alternating magnetic fields with different amplitudes under the first frequency, wherein M is an integer more than or equal to 2;
s2: and carrying out orthogonal demodulation processing on corresponding output by using the magnetic field frequency, carrying out low-pass filtering on demodulated data, taking a frequency doubling amplitude after the low-pass filtering as accelerometer output, bringing acceleration input corresponding to an accelerometer testing device into an output model of the accelerometer, carrying out least square fitting on the accelerometer output to obtain accelerometer model parameters corresponding to the group of output, and fitting each model parameter respectively about the magnetic field amplitude to obtain the respective magnetic vector sensitivity of the accelerometer model parameters under the first magnetic field frequency.
Further, considering that the accelerometer may have different responses to magnetic fields of different frequencies, after step S2, the method further includes:
s3: generating an alternating magnetic field with a first amplitude and a second frequency by a magnetic field generating device, and collecting the output of the accelerometer as a first output;
changing the amplitude of the magnetic field to enable the magnetic field generating device to generate an alternating magnetic field with a second amplitude and a second frequency, and collecting the output of the accelerometer as a second output;
Repeating the process for M times to obtain M groups of accelerometer outputs under the alternating magnetic fields with different amplitudes under the second frequency, wherein M is an integer more than or equal to 2;
s4: and performing orthogonal demodulation processing on the corresponding output obtained in the step S3 by using the magnetic field frequency used in the step S3, performing low-pass filtering on the demodulated data, performing data processing on the low-pass filtered frequency multiplication amplitude according to a method corresponding to the accelerometer testing device to obtain accelerometer model parameters corresponding to the group of outputs, and fitting each model parameter with respect to the magnetic field amplitude respectively to obtain the respective magnetic vector sensitivity of the accelerometer model parameters under the second magnetic field frequency.
Further, by changing the magnetic field frequency and sequentially setting the magnetic field frequency to the third frequency, the fourth frequency and the fifth frequency … …, repeating the steps S3 and S4N times, the magnetic vector sensitivities of the accelerometer model parameters at N sets of magnetic field frequencies are obtained, where N is an integer greater than or equal to 2.
Further, the first frequency is set as the frequency of the alternating magnetic field in the environment where the accelerometer is applied, the first amplitude is set as a smaller amplitude larger than zero, the Mth amplitude is set as the amplitude of the magnetic field intensity in the environment where the accelerometer is applied, and the second amplitude, the third amplitude and the … … Mth amplitude are sequentially increased step by step at equal intervals.
Further, before step S1, the method further includes: the accelerometer is arranged in a mode that a sensitive shaft and an output shaft are parallel to a mounting surface, a pendulum shaft is perpendicular to the mounting surface, and the sensitive shaft is parallel to the direction of a magnetic field.
Further, the arrangement of the accelerometer sensitivity axis relative to the magnetic field direction change is achieved by rotating the accelerometer 90 ° about the tilt axis or rotating the magnetic field direction 90 °.
Further, in step S1, the multi-position static test is performed after the accelerometer testing apparatus is tilted to a fixed angle within the range of the accelerometer.
Further, in step S1, the sampling frequency at which the accelerometer outputs is greater than the magnetic field change frequency.
Compared with the prior art, the measuring method provided by the invention has the following technical advantages:
(1) according to the invention, a magnetic field is used as a vector to be researched, a space angle relation between a magnetic vector direction generated by a magnetic field generating device and an accelerometer testing device is added into a testing condition, and the influence of the magnetic vector direction on the accelerometer is taken into consideration. One of the characteristics of the invention is as follows: the spatial angle relation between the direction of the magnetic vector generated by the magnetic field generating device and the accelerometer testing device is kept unchanged, so that the angle relation between the sensitive axis of the accelerometer and the direction of the magnetic field is kept unchanged in the detection process; therefore, when the input acceleration along each axis of the accelerometer is changed, the magnetic field environment where each axis of the accelerometer is located is not changed, and errors caused by the change of the direction of the accelerometer relative to the magnetic field are avoided.
(2) According to the invention, the respective magnetic vector sensitivities of the accelerometer model parameters are separated from the magnetic field response of the total output of the accelerometer, and the accelerometer model parameters can be used for data compensation; the requirements of the accelerometer on magnetic shielding in an application environment are reduced, and the output accuracy of the accelerometer is improved.
(3) The magnetic vector sensitivity of the accelerometer model parameters under the magnetic fields with different frequencies can be obtained by changing the frequency of the magnetic field, so that more accurate data support is provided for the application of the accelerometer; the problem that the frequency response of the accelerometer to the environmental magnetic field is not considered in the traditional test method is solved.
Drawings
FIG. 1 is a flowchart of a method for separating sensitivity of a parameter vector of an accelerometer model according to an embodiment of the present invention;
FIG. 2 is a schematic view of an accelerometer assembly according to an embodiment of the invention;
FIG. 3 is a schematic diagram of the coordinate system and the rotation relationship according to the present invention, wherein (a) is the initial installation coordinate system of the accelerometer, (b) is the coordinate system of the accelerometer following the inclination angle γ of the testing device, and (c) is the rotation angle θ in the inclined planejThe latter coordinate system.
In the figure, the same reference numerals denote the same physical quantities, 1 denotes an accelerometer, 2 denotes the directions of an Input Axis (IA), an Output Axis (OA), and a Pivot Axis (PA) of the accelerometer, 3 denotes a magnetic field generating device, 4 denotes a magnetic field direction, 5 denotes a mounting table of a magnetic field uniform region, and 6 denotes an accelerometer testing device.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
The method for measuring the magnetic vector sensitivity of the accelerometer model parameters can be applied to various high-resolution accelerometers, and is particularly suitable for testing the magnetic vector sensitivity of ng-grade accelerometers.
The device for measuring the sensitivity of the magnetic vector comprises two modules: the device comprises an acceleration generation module and a magnetic field generation module, wherein the acceleration generation module is used for providing variable and quantifiable acceleration input for an accelerometer; the magnetic field generation module is used for providing a variable and stable magnetic field environment for the accelerometer.
The acceleration generation module can be a dividing head, a precision centrifuge or a precision line vibration table, and the magnetic field generation module can be a Helmholtz coil or a solenoid.
The test device adopted by the method for measuring the sensitivity of the magnetic vector of the accelerometer model parameter provided by the embodiment of the invention fixedly connects the acceleration generation module and the magnetic field generation module together through the screw or other mounting clamps, and innovatively realizes that when the acceleration generation module is used, the magnetic field generation module has the same pose change as the acceleration generation module, so that the magnetic field environment of the accelerometer to be measured arranged in the magnetic field generation module is unchanged when the input acceleration is changed. When the direction of the magnetic field changes relative to the accelerometer, the magnetic field components along the sensitive axis of the accelerometer and the sensitive axis of the vertical accelerometer change at the same time, so that the effect caused by the change of the magnetic sensitivity and the external magnetic field cannot be separated. The invention avoids the problem that once the input acceleration on the accelerometer is changed, the direction of the magnetic field relative to the accelerometer is also changed in the existing magnetic sensitivity testing device, thereby eliminating the coupling between the response of the accelerometer about the direction of the magnetic field and the magnetic sensitivity of the accelerometer in the testing process.
The invention provides a method for measuring the sensitivity of a magnetic vector of a parameter of an accelerometer model, which comprises the following steps:
(1) the magnetic field generating device is fixed on the accelerometer testing device, for example, the spiral coil magnetic field generating device is fixed on the dividing head, and the accelerometer is arranged in a magnetic field uniform area in the magnetic field generating device so as to avoid the response of the accelerometer to the magnetic field gradient and improve the testing precision of the magnetic vector sensitivity;
(2) the method comprises the steps that a magnetic field generating device generates an alternating magnetic field with an amplitude value of a first amplitude value and a frequency of the first frequency, then an accelerometer testing device is tested according to the using rules of the alternating magnetic field, the magnetic field generating device and the accelerometer testing device are fixedly connected through screws, and an accelerometer to be tested and the magnetic field generating device are fixedly connected, so that the magnetic field generating device and the accelerometer to be tested can be guaranteed to follow the pose state of the accelerometer testing device, the relation between the direction of a magnetic vector generated by the magnetic field generating device and the space angle between the accelerometers to be tested is guaranteed to be unchanged during testing, and the output of the accelerometer is collected as first output; changing the amplitude of the magnetic field to enable the magnetic field generating device to generate an alternating magnetic field with a second amplitude and a first frequency, collecting the output of the accelerometer as a second output, repeating for M times, and collecting the output of the accelerometer under M groups of alternating magnetic fields with different amplitudes and the first frequency, wherein M is an integer greater than or equal to 2;
Wherein the first frequency may be set to the frequency of the alternating magnetic field at the environment in which the accelerometer is applied, or other user-interested frequencies, such as 0.5 Hz; the first amplitude may be set to some small amplitude greater than zero, such as 1Gs, and the mth amplitude may be set to the amplitude of the magnetic field strength at the environment where the accelerometer is applied, or other magnetic field strength of interest to the user, such as 10Gs, the second amplitude, the third amplitude, etc., in steps that are incrementally increased at equal intervals as compared to the first amplitude.
(3) Performing orthogonal demodulation processing on the corresponding output obtained in the step (2) by using the magnetic field frequency used in the step (2), performing low-pass filtering on demodulated data, taking a frequency doubling amplitude after the low-pass filtering as an accelerometer output, bringing the acceleration input corresponding to the accelerometer testing device into an output model of the accelerometer, performing least square fitting on the accelerometer output to obtain accelerometer model parameters corresponding to the group of outputs, and fitting each model parameter with respect to the magnetic field amplitude respectively to obtain the respective magnetic vector sensitivity of the accelerometer model parameters under the first magnetic field frequency;
further, considering that the accelerometer may have different responses to magnetic fields of different frequencies, the following steps are proposed in the detection process:
(4) Enabling the magnetic field generating device to generate an alternating magnetic field with a first amplitude and a second frequency, enabling the accelerometer testing device to test according to the using rule of the alternating magnetic field, keeping the spatial angle relation between the direction of a magnetic vector generated by the magnetic field generating device and the accelerometer testing device unchanged during the testing, and collecting the output of the accelerometer as a first output; changing the amplitude of the magnetic field to enable the magnetic field generating device to generate an alternating magnetic field with a second amplitude and a second frequency, collecting the output of the accelerometer as a second output, repeating for M times, and collecting the output of the accelerometer under M groups of alternating magnetic fields with different amplitudes and second frequencies, wherein M is an integer greater than or equal to 2;
(5) performing orthogonal demodulation processing on the corresponding output obtained in the step (4) by using the magnetic field frequency used in the step (4), performing low-pass filtering on demodulated data, performing data processing on a frequency doubling amplitude value after the low-pass filtering according to a method corresponding to an accelerometer test device to obtain accelerometer model parameters corresponding to the group of output, and fitting each model parameter with respect to the magnetic field amplitude value respectively to obtain the respective magnetic vector sensitivity of the accelerometer model parameters under the second magnetic field frequency;
(6) In the step (4), changing the magnetic field frequency to be a third frequency, repeating the steps (4) and (5) for N times, wherein N is an integer greater than or equal to 2, and then obtaining the magnetic vector sensitivity of the accelerometer model parameters under N groups of magnetic field frequencies.
Wherein the first frequency may be set to the frequency of the alternating magnetic field in the environment where the accelerometer is applied, or other user-interested frequency, such as 1Hz, the nth frequency may be set to some smaller frequency greater than zero, such as 0.1Hz, the second amplitude, the third amplitude, etc., and gradually decreased at equal intervals compared to the first amplitude.
In the embodiment of the present invention, before step (1), the following steps are further included: the accelerometer is arranged in a mode that a sensitive shaft and an output shaft are parallel to a mounting surface, a pendulum shaft is perpendicular to the mounting surface, and the sensitive shaft is parallel to the direction of a magnetic field.
As an embodiment of the present invention, in step (2) and step (4), for the ng-class accelerometer, because its range limitation cannot be rolled in the 1-g gravity field or tested on the centrifuge, the accelerometer testing device, such as the index head, can be tilted to a fixed angle within the range of the accelerometer, and then the multi-position static test is performed.
In addition, in the step (2) and the step (4), the sampling frequency when the output of the accelerometer is collected is greater than the magnetic field change frequency, so as to avoid the occurrence of aliasing phenomenon
In the embodiment of the invention, the cut-off frequency of the low-pass filtering is smaller than the magnetic field change frequency so as to eliminate other alternating current signals when a frequency doubling amplitude value is obtained.
In the embodiment of the present invention, step (7) is further included after step (6): and (4) arranging the accelerometer in a manner that a sensitive axis and an output axis are parallel to the mounting surface, a pendulum axis is perpendicular to the mounting surface and the sensitive axis is perpendicular to the direction of the magnetic field, and repeating the steps (1) to (6) to obtain the respective magnetic vector sensitivities of the model parameters when the sensitive axis of the accelerometer is perpendicular to the direction of the magnetic field.
The arrangement of the change of the sensitive axis of the accelerometer relative to the direction of the magnetic field is realized by rotating the accelerometer by 90 degrees around the pendulum axis or rotating the direction of the magnetic field by 90 degrees.
The method changes the input acceleration of the accelerometer in the magnetic field environment through the step (2), and solves the model parameters of the accelerometer under different magnetic field conditions through the step (3). Compared with the existing magnetic sensitivity test method, the method innovatively separates the magnetic vector sensitivity of each model parameter of the accelerometer, and refines the overall response rule of the accelerometer to the magnetic field into the response rule of each model parameter to the magnetic field. In addition, the magnetic sensitivity of the accelerometer in external magnetic fields with different frequencies can be obtained by supplementing the steps (4) and (5), and compared with a single magnetic field frequency used in the existing test method, the method can distinguish the magnetic induction phenomenon (related to the magnetic field frequency) of the accelerometer due to the alternating magnetic field from the magnetic sensitivity effect of the accelerometer. The magnetic shielding requirement of the accelerometer can be more accurately provided according to the test result of the scheme, or each model parameter is compensated with respect to the magnetic field, so that the response of the accelerometer to the magnetic field is reduced.
The invention provides a method for measuring the sensitivity of a magnetic vector of a parameter of an accelerometer model. The method comprises the steps of installing a magnetic field generating device on an accelerometer testing device, installing an accelerometer in a uniform magnetic field region generated by the magnetic field generating device, keeping a spatial angle relation between a magnetic vector direction generated by the magnetic field generating device and the accelerometer testing device unchanged, testing by using the accelerometer testing device under different magnetic field amplitudes, separately setting accelerometer model parameters under a magnetic field, detecting magnetic vector sensitivity of model parameters of the accelerometer by using the dependency relation between the model parameters and the magnetic field amplitudes, and changing magnetic field frequencies to repeat the steps to obtain the magnetic vector sensitivity under different magnetic field frequencies.
To further illustrate the present invention, reference will now be made in detail to the following examples, taken in conjunction with the accompanying drawings, in which: as shown in fig. 1, taking a dividing head as an example of an accelerometer test device, the specific method steps are as follows:
(1) the accelerometer is installed in the uniform magnetic field area of the magnetic field generating device according to the installation mode shown in figure 2, and the magnetic field generating device is installed on the dividing head according to the installation mode shown in figure 2, so that a rigid whole is formed.
(2) The magnetic field generator is mainly used to realize an alternating magnetic field with variable amplitude a and frequency f, for example, a is set to [1, 7] Gs and f is set to 0.25 Hz. The index head is mainly used for realizing biaxial angle positioning and indexing functions, the inclined shaft of the index head is adjusted to be inclined at an angle gamma of 0.01 degrees or 90 degrees with the horizontal plane, the rotating shaft is arranged to stop at every 360 degrees/n angle positions, and n is a multiple of 4, for example, n is 12.
The accelerometer is mounted in the manner shown in fig. 2 with the sensitive axis (IA) and the Output Axis (OA) of the accelerometer in the mounting plane, with IA along the magnetic field direction, OA perpendicular to the magnetic field direction, and the yaw axis (PA) perpendicular to the mounting plane. Taking the IA along the magnetic field direction as an example, the mounting manner of the IA perpendicular to the magnetic field direction can be obtained by rotating the accelerometer around PA by 90 °.
As shown in (a), (b) and (c) in FIG. 3, wherein OX is defined0Y0Z0For an initial mounting coordinate system of the accelerometer, the sensitive axis IA of the accelerometer is set along OY0In the direction of the output axis OA along OX0Direction, pendulum axis PA along OZ0In the opposite direction of (OX)1Y1Z1For tilting the index head to the coordinate system of the gamma rear accelerometer, the index head is set around OX1Tilt, OX2Y2Z2For indexing heads around OZ1The rotating coordinate system has a rotation angle thetajN is a multiple of 4, for example, n is set to 12. In the above process, the magnetic field generating device and the accelerometer rotate together with the index head as a whole.
From the changing relationship between the coordinate systems, the coordinate system OX can be derived0Y0Z0To a coordinate system OX2Y2Z2The transformation of (a):
gravity on each axis of accelerometer (coordinate system OX)2Y2Z2) The component above is:
(3) setting accelerometer outputSampling frequency fsSaid sampling frequency fsMuch higher than the magnetic field frequency in step (1), e.g. setting fs＝100Hz，f＝0.25Hz。
(4) The dividing head drives the magnetic field generating device and the accelerometer to start n-position static test at a set rotary angle position, and the spatial angle relationship between the direction of the magnetic vector generated by the magnetic field generating device and the accelerometer test device is kept unchanged during the period, and a formula is output through the accelerometer:
the output of the accelerometer at different rotational angle positions can be written:
E＝K0+K1gsinγsinθj+K2g2sin2γsin2θj+K4g2sinγcosγsinθj+K6g2sin2γsinθjcosθj+K8g2sinγcosγcosθj+K5g2sin2γcos2θj+K7g2cos2γ-δPgsinγcosθj+δOgcosγ
the rotation angle position is changed every t minutes until the set rotation angle is completed.
In particular, for the case where zero bias and scaling factor are simply required, a simplified accelerometer output formula can be used:
or a further simplified output formula:
E＝K0+K1aI
when a further simplified output formula is used, n may be set to 4 to shorten the total detection time period.
(5) Orthogonal demodulation is carried out on the output signal of the accelerometer at the corresponding magnetic field frequency, a frequency doubling (including sine and cosine signals) about the magnetic field frequency in the output of the accelerometer is screened out, then low-pass filtering is carried out, the filtering cutoff frequency is far smaller than f, and a frequency doubling amplitude of the accelerometer under different magnetic field amplitudes is obtained.
(6) And (5) fitting the result obtained in the step (4) with respect to the accelerometer output equation obtained in the step (3) to obtain model parameters of the accelerometer under the corresponding magnetic field amplitude. And fitting the model parameters under each magnetic field amplitude with respect to the corresponding magnetic field amplitude respectively to obtain a coefficient, namely the magnetic vector sensitivity of each model parameter of the accelerometer.
(7) The setting magnetic field generating device realizes the alternating magnetic field of the second frequency, for example, setting a to [1, 7] Gs and f to 0.5Hz, while maintaining the accelerometer attachment mode of step (1). And (5) repeating the steps (2) to (6) to obtain the magnetic vector sensitivity of the accelerometer model parameters under the second magnetic field frequency.
(8) Changing the alternating magnetic field frequency realized by the magnetic field generating device, repeating the step (7) until the set magnetic field frequency is completely tested, and obtaining the magnetic vector sensitivity of the accelerometer model parameters under different magnetic field frequencies
(9) And (3) arranging the accelerometer in a manner that a sensitive axis and an output axis are parallel to the mounting surface, a pendulum axis is perpendicular to the mounting surface and the sensitive axis is perpendicular to the direction of the magnetic field, and repeating the steps (2) to (8) to obtain the respective magnetic vector sensitivities of the model parameters when the sensitive axis of the accelerometer is perpendicular to the direction of the magnetic field.
In summary, the invention has the following advantages:
(1) the sensitivity of the accelerometer to all directions of magnetic vectors is considered, the magnetic response caused by the change of an included angle between a sensitive axis of the accelerometer and the direction of the magnetic field in the detection process is avoided by keeping the spatial angle relationship between the direction of the magnetic vectors generated by the magnetic field generating device and the accelerometer testing device unchanged, the angle relationship between the sensitive axis of the accelerometer and the direction of the magnetic field is added into the testing condition, the response of the accelerometer to the magnetic fields in different directions can be given more specifically, and compared with the maximum response of the accelerometer in the magnetic field, the testing result of the invention can reduce the requirement of the accelerometer on magnetic shielding in some directions;
(2) the respective magnetic vector sensitivities of the accelerometer model parameters are separated, and the accelerometer model parameters can be used for data compensation;
(3) magnetic vector sensitivity of the accelerometer under magnetic fields of different frequencies can be obtained.
It will be understood by those skilled in the art that the foregoing is only an exemplary embodiment of the present invention, and is not intended to limit the invention to the particular forms disclosed, since various modifications, substitutions and improvements within the spirit and scope of the invention are possible and within the scope of the appended claims.
Claims (8)
1. A method for realizing measurement of accelerometer model parameter magnetic vector sensitivity based on a measuring device is characterized in that,
The measuring device comprises an acceleration generating module and a magnetic field generating module which are fixedly connected, wherein the acceleration generating module is used for providing variable and quantifiable acceleration input for the accelerometer; the magnetic field generation module is used for providing a variable and stable magnetic field environment for the accelerometer; when the acceleration generating module is used, the magnetic field generating module has the same pose change as the acceleration generating module, so that the magnetic field environment of an accelerometer to be tested arranged in the magnetic field generating module is unchanged when the input acceleration is changed;
the method comprises the following steps:
s1: generating an alternating magnetic field with a first amplitude and a first frequency through a magnetic field generating module, and collecting the output of an accelerometer as a first output;
by changing the amplitude of the magnetic field, the magnetic field generation module generates an alternating magnetic field with a second amplitude and a first frequency, and acquires the output of the accelerometer as a second output;
repeating the steps M times and obtaining accelerometer outputs under M groups of alternating magnetic fields with different amplitudes under the first frequency, wherein M is an integer more than or equal to 2;
s2: and carrying out orthogonal demodulation processing on corresponding output by utilizing the first frequency, carrying out low-pass filtering on demodulated data, taking a frequency doubling amplitude after the low-pass filtering as accelerometer output, bringing acceleration input corresponding to the measuring device into an output model of the accelerometer, carrying out least square fitting on the accelerometer output to obtain accelerometer model parameters corresponding to the group of output, and fitting each model parameter respectively about the magnetic field amplitude to obtain the respective magnetic vector sensitivity of the accelerometer model parameters under the first frequency.
2. The method of claim 1, further comprising, after step S2:
s3: generating an alternating magnetic field with a first amplitude and a second frequency by a magnetic field generating module, and collecting the output of the accelerometer as a first output;
changing the amplitude of the magnetic field to enable the magnetic field generation module to generate an alternating magnetic field with a second amplitude and a second frequency, and collecting the output of the accelerometer as a second output;
repeating the steps for M times to obtain M groups of accelerometer outputs under the alternating magnetic fields with different amplitudes under the second frequency, wherein M is an integer more than or equal to 2;
s4: and performing orthogonal demodulation processing on the corresponding output obtained in the step S3 by using the second frequency used in the step S3, performing low-pass filtering on the demodulated data, performing data processing on the low-pass filtered frequency multiplication amplitude according to a method corresponding to the measuring device to obtain accelerometer model parameters corresponding to the group of outputs, and fitting each model parameter with respect to the magnetic field amplitude to obtain the respective magnetic vector sensitivity of the accelerometer model parameters under the second frequency.
3. The method of claim 2, wherein the magnetic vector sensitivities of the accelerometer model parameters at N sets of magnetic field frequencies are obtained after repeating steps S3 and S4N times by changing the magnetic field frequency and sequentially setting to the third frequency, the fourth frequency, and the fifth frequency … …, where N is an integer greater than or equal to 2.
4. A method according to any one of claims 1 to 3, wherein the first frequency is set to the frequency of the alternating magnetic field at the environment of application of the accelerometer, the first amplitude is set to a smaller amplitude greater than zero, the mth amplitude is set to the amplitude of the magnetic field at the environment of application of the accelerometer, and the second amplitude, the third amplitude and the … … mth amplitude are sequentially incremented at equal intervals.
5. The method according to any of claims 1-3, further comprising, before step S1: the accelerometer is arranged in a mode that a sensitive shaft and an output shaft are parallel to a mounting surface, a pendulum shaft is perpendicular to the mounting surface, and the sensitive shaft is parallel to the direction of a magnetic field.
6. A method according to claim 5, wherein the setting of the change in the sensitivity axis of the accelerometer relative to the direction of the magnetic field is achieved by rotating the accelerometer 90 ° about the tilt axis or by rotating the direction of the magnetic field by 90 °.
7. The method of any of claims 1-3, wherein the multi-position static test is performed after the accelerometer is tilted to a fixed angle within the range of the accelerometer in step S1.
8. The method of claim 3, wherein in step S1, the sampling frequency at which the accelerometer outputs is greater than the magnetic field frequency.
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Citations (3)
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| SU924583A1 (en) * | 1978-07-10 | 1982-04-30 | Московский Ордена Ленина Авиационный Институт Им.С.Орджоникидзе | Pendulum acceleration meter |
| CN205808544U (en) * | 2016-06-02 | 2016-12-14 | 长沙湘计海盾科技有限公司 | A kind of fibre optic hydrophone acceleration sensitivity test system |
| CN109782023A (en) * | 2019-01-25 | 2019-05-21 | 华中科技大学 | A method of accelerometer higher order term number system number is measured by rotation modulation method |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU924583A1 (en) * | 1978-07-10 | 1982-04-30 | Московский Ордена Ленина Авиационный Институт Им.С.Орджоникидзе | Pendulum acceleration meter |
| CN205808544U (en) * | 2016-06-02 | 2016-12-14 | 长沙湘计海盾科技有限公司 | A kind of fibre optic hydrophone acceleration sensitivity test system |
| CN109782023A (en) * | 2019-01-25 | 2019-05-21 | 华中科技大学 | A method of accelerometer higher order term number system number is measured by rotation modulation method |
Non-Patent Citations (1)
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| 压电加速度传感器磁灵敏度的多维测试方法的研究;黄志煌;《计量与测试技术》;20191130;第46卷(第11期);第52页 * |
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