An electrostatic accelerometer based on data fusion to reduce measurement errors

Abstract

The present application provides an electrostatic accelerometer for reducing measurement errors based on data fusion, which belongs to the field of acceleration sensor testing; the electrostatic accelerometer includes: a sensitive probe, a measurement control module and a data processing module; one end of the sensitive probe is connected to the measurement control module; the measurement control module is connected to the data processing module; the measurement control module is used to collect the displacement of the inspection mass in the sensitive probe, and convert the displacement signal into a feedback voltage signal and apply it to the capacitor plate in the sensitive probe to generate an electrostatic force; the data processing module is used to collect the feedback voltage signal in the measurement control module and the residual voltage related to the inspection mass displacement and perform analog-to-digital conversion and then fuse it, compensate for the input acceleration measurement error term related to the relative position, and extract the measurement result of the external input acceleration. The present application improves the measurement speed of the electrostatic accelerometer.

Description

Technical Field

[0001] The present application belongs to the field of acceleration sensor testing, and more specifically, relates to an electrostatic accelerometer for reducing measurement errors based on data fusion. Background Art

[0002] High-precision electrostatic accelerometers, as indispensable payloads in key missions such as satellite gravity measurement, have achieved remarkable and extensive application results in international space exploration. In space science research, the continuous improvement of inertial sensor accuracy has become a key issue that needs to be solved urgently. The core operating mechanism of the electrostatic accelerometer relies on the test mass in its sensitive probe. As the benchmark for inertial measurement, the test mass plays a vital role. When the spacecraft is disturbed by external non-conservative forces, the test mass will deviate from its equilibrium position, thereby causing a change in the capacitance value between it and the corresponding plate. The capacitance difference is accurately measured by the capacitive displacement sensing circuit and converted into the displacement information of the test mass relative to the equilibrium point, that is, the residual signal.

[0003] Subsequently, the residual signal is processed by the controller and converted into a corresponding feedback voltage, which acts on the electrostatic actuator to generate a suitable electrostatic force to accurately pull the test mass back to the equilibrium position. In this process, the acceleration generated by the electrostatic actuator structure matches the acceleration of the spacecraft. This equilibrium relationship can be described by the following expression:

[0004]

[0005] Among them, a in is the external input acceleration; a n,dir is the direct disturbance acceleration of the test mass; a f is the feedback acceleration generated on the test mass by the electrostatic force; x is the relative position between the test mass and the capacitor plate; is the electrostatic negative stiffness represented by angular frequency; s represents the first differential link.

[0006] Traditional electrostatic accelerometers will feedback acceleration a f As the external input acceleration a in The approximate measurement result of f It can be calculated from the feedback voltage data. The calculation process is shown in formula (2):

[0007] a f =H a ·V f (2)

[0008] Among them, H a is the feedback actuator transfer function, V f is the feedback voltage;

[0009] As the core device in the inertial system, the electrostatic accelerometer has high requirements for its accuracy and response speed. However, under the existing measurement method, when the spacecraft is in a maneuvering state, the electrostatic accelerometer is sensitive to the external input acceleration a. in The measurement results have a certain tracking delay and cannot meet the response speed requirements. Summary of the invention

[0010] In view of the defects of the prior art, the purpose of this application is to provide an electrostatic accelerometer based on data fusion to reduce measurement errors, aiming to solve the problem that the existing electrostatic accelerometers have tracking delays and cannot meet the requirements of fast response tasks.

[0011] To achieve the above-mentioned purpose, in a first aspect, the present application provides an electrostatic accelerometer, comprising: a sensitive probe, a measurement control module and a data processing module;

[0012] One end of the sensitive probe is connected to the measurement control module; the measurement control module is connected to the data processing module;

[0013] The measurement control module is used to collect the displacement of the inspection mass in the sensitive probe, convert the displacement signal into a feedback voltage signal and apply it to the capacitor plate in the sensitive probe to generate electrostatic force; the data processing module is used to collect the feedback voltage signal in the measurement control module and the residual voltage related to the inspection mass displacement and perform analog-to-digital conversion and then fuse them, compensate for the input acceleration measurement error term related to the relative position, and extract the measurement result of the external input acceleration;

[0014] Here, the relative position is the relative position between the test mass and the capacitor plates.

[0015] Further preferably, the measurement control module comprises: a capacitive displacement sensing circuit, a controller and a feedback actuator;

[0016] The input end of the capacitive displacement sensing circuit is connected to the capacitive plate in the sensitive probe, and the output end thereof is connected to the controller; the input end of the feedback actuator is connected to the controller, and the output end thereof is connected to the capacitive plate;

[0017] The test mass is used to generate displacement relative to the equilibrium position under the action of external interference force; the capacitive displacement sensing circuit is used to measure the position of the test mass in the capacitor plate and convert the displacement signal into a voltage signal; the controller is used to convert the displacement signal into a feedback voltage and transmit it to the feedback actuator; the feedback actuator is used to apply the feedback voltage obtained by the controller to the capacitor plate to generate electrostatic force.

[0018] Further preferably, the data processing module includes a first analog-to-digital converter, a second analog-to-digital converter and a data fusion processor;

[0019] The input end of the first analog-to-digital converter is connected to the capacitive displacement sensing circuit, and the output end thereof is connected to the data fusion processor; the input end of the second analog-to-digital converter is connected to the output end of the feedback actuator, and the output end thereof is connected to the data fusion processor;

[0020] The first analog-to-digital converter and the second analog-to-digital converter are used to convert the residual voltage signal and the feedback voltage signal from analog signals into digital signals respectively; the data fusion processor is used to fuse the residual voltage signal and the feedback voltage signal of the digital signal to extract the measurement result of the accelerometer.

[0021] Further preferably, the measurement result expression of the external input acceleration is:

[0022]

[0023] Among them, a mea Represents the measurement result of external input acceleration; H sx is the capacitance sensitivity; H sc is the transfer function of the capacitive displacement sensing circuit; V err is the residual voltage; s 2 For the residual voltage V err The second derivative of is the electrostatic negative stiffness characterized by angular frequency; H a is the feedback actuator transfer function; V f is the feedback voltage.

[0024] Further preferably, a linear tracking differentiator is provided in the data fusion processor to obtain a first differential expression of the residual voltage so as to calculate the residual voltage V err The transfer function of the linear tracking differentiator is:

[0025]

[0026] Where y represents V err The first differential of Instead of S; T1 and T2 are the time constants of the two inertial links respectively; among them, the linear tracking differentiator consists of two inertial links The difference between the forward gain Connected.

[0027] In a second aspect, the present application provides a method for acquiring acceleration based on the above-mentioned electrostatic accelerometer, which specifically comprises the following steps:

[0028] The displacement of the inspection mass in the sensitive probe is collected, and the displacement signal is converted into a feedback voltage signal and applied to the capacitor plate in the sensitive probe to generate an electrostatic force;

[0029] The feedback voltage signal and the residual voltage related to the displacement of the inspection mass are collected and fused after analog-to-digital conversion, the input acceleration measurement error term related to the relative position is compensated, and the measurement result of the external input acceleration is extracted;

[0030] Here, the relative position is the relative position between the test mass and the capacitor plates.

[0031] Further preferably, the measurement result expression of the external input acceleration is:

[0032]

[0033] Among them, a mea Represents the measurement result of external input acceleration; H sx is the capacitance sensitivity; H sc is the transfer function of the capacitive displacement sensing circuit; V err is the residual voltage; s 2 For the residual voltage V err The second derivative of is the electrostatic negative stiffness characterized by angular frequency; H a is the feedback actuator transfer function; V f is the feedback voltage.

[0034] Further preferably, a linear tracking differentiator is used to obtain a first differential expression of the residual voltage, and the transfer function of the linear tracking differentiator is:

[0035]

[0036] Where y represents V err The first differential of Instead of s; T1 and T2 are the time constants of the two inertial links respectively; among them, the linear tracking differentiator consists of two inertial links The difference between the forward gain Connected.

[0037] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art:

[0038] The present application provides an electrostatic accelerometer based on data fusion to reduce measurement errors. The traditional electrostatic accelerometer measurement scheme ignores the input acceleration measurement error term related to the relative position x. When the spacecraft is in a maneuvering state, the relative position x has rapid and large fluctuations, resulting in This acceleration measurement error term also has rapid and large fluctuations, which ultimately leads to certain tracking errors and delays in the electrostatic accelerometer measurement results. Based on the traditional electrostatic accelerometer, this application adds a data fusion processor to correlate the residual voltage data with the feedback voltage data, compensating for the input acceleration measurement error term related to the relative position x of the test mass and the plate. This improves the measurement speed of the accelerometer; at the same time, it is proposed to use a linear tracking differentiator to realize the secondary differential of the residual voltage 2 , thereby effectively reducing the noise interference in the process of implementing the data fusion processing module technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 1 is a control schematic diagram of an electrostatic accelerometer for implementing plate pair control provided in an embodiment of the present application; wherein the serial numbers in the figure represent: 1-test mass; 2-capacitor plate; 3-capacitor displacement sensing circuit; 4-controller; 5-feedback actuator; 6-signal driver: bias voltage and carrier driver; 7-data fusion processor;

[0040] Figure 2 is a closed-loop schematic diagram of an electrostatic accelerometer provided in an embodiment of the present application, which includes: probe capacitance sensitivity H sx , the displacement sensing circuit transfer function H sc , controller transfer function K sus and feedback actuator transfer function H a ;

[0041] Figure 3 is a schematic diagram of a linear tracking differentiator provided in an embodiment of the present application;

[0042] Figure 4 are the measurement results of the electrostatic accelerometer under different schemes provided in the embodiments of the present application, wherein the yellow dotted line is the external input acceleration a in , the blue solid line is the feedback acceleration a f The red and purple solid lines are the output results of the electrostatic accelerometer using the linear tracking differentiator and the classical differential link for data fusion processing. mea , DETAILED DESCRIPTION

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

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

[0045] The present application provides an electrostatic accelerometer for reducing measurement errors based on data fusion, and can improve the measurement speed of the electrostatic accelerometer by fusing feedback voltage and residual voltage data.

[0046] Implementation example Figure 1 As shown, the present application provides an electrostatic accelerometer for reducing measurement errors based on data fusion, comprising: a test mass 1, a capacitor plate 2, a capacitive displacement sensing circuit 3, a controller 4, a feedback actuator 5, a signal driver 6, a data fusion processor 7 and an analog-to-digital converter ADC; the sensitive probe comprises a test mass 1 and a capacitor plate 2;

[0047] Two capacitor plates 2 are arranged in parallel on each side of the inspection mass 1; the input end of the capacitance displacement sensing circuit 3 is connected to the capacitor plate 2, and the output end thereof is connected to the controller 4; the output end of the controller 4 is connected to the feedback actuator 5; the output end of the feedback actuator 5 is connected to the capacitor plate 2; the output end of the signal driver 6 is connected to the inspection mass 1 through a gold wire;

[0048] The sensitive probe includes a capacitor plate and a test mass; the test mass is used to generate displacement relative to the equilibrium position under the action of external interference force; the capacitive displacement sensing circuit is used to test the position of the test mass in the capacitor plate and convert the displacement signal into a voltage signal; the controller is used to convert the displacement signal into a feedback voltage and transmit it to the feedback actuator, wherein the feedback voltage is used to control the test mass; the feedback actuator is used to apply the feedback voltage obtained by the controller to the capacitor plate to generate electrostatic force; the signal driver is used to provide a carrier signal and a DC bias voltage to the test mass, wherein the carrier is used to modulate the capacitance difference signal generated by the displacement of the test mass to a preset frequency, and the bias voltage is used to linearize the feedback actuator; the data fusion processor is used to fuse the feedback voltage and the residual voltage signal, compensate for the input acceleration measurement error term related to the relative position of the test mass and the capacitor plate, and extract the measurement result of the accelerometer; the analog-to-digital converter ADC is used to convert the feedback voltage signal and the residual voltage signal from analog signals to digital signals.

[0049] Traditional electrostatic accelerometers use feedback voltage data to calculate feedback acceleration and use it as the measurement result of external input acceleration. In order to improve the response characteristics of the electrostatic accelerometer, this application introduces residual voltage data related to the displacement of the test mass on the basis of the feedback voltage, and performs fusion processing. A new input acceleration measurement result is obtained through correction calculation. This measurement result can quickly reflect the acceleration information of the spacecraft.

[0050] Based on the feedback voltage V f and the residual voltage V err The measurement principle of electrostatic accelerometer with data fusion processing is as follows Figure 2 As shown by Figure 2It can be seen that the external input acceleration measurement results are as follows:

[0051]

[0052] Among them, a mea It represents the output result of the electrostatic accelerometer after data fusion processing, H sx is the capacitance sensitivity, H sc is the transfer function of the capacitive displacement sensing circuit, V err is the residual voltage; s 2 Represents the residual voltage V err The second derivative of

[0053] From the comparison with the traditional measurement scheme (Formula 2), it can be seen that the new measurement result is obtained by fusion processing of feedback voltage and residual voltage data, and the input acceleration measurement error term related to the relative position x of the test mass and the plate can be Compensate for it, thereby reducing the gap between the measured value of the electrostatic accelerometer and the true value;

[0054] Formula (3) is a theoretical formula. In practical applications, the residual voltage V err is contaminated by noise. If we directly use the second derivative to realize the second differential s 2 , it will amplify the noise and affect the measurement stability of the accelerometer. In order to reasonably extract the secondary differential signal from the residual voltage signal contaminated by noise, a linear tracking differentiator is used, which has the function of noise suppression and rapid extraction of the required differential signal.

[0055] The principle of linear tracking differentiator is as follows Figure 3 As shown, there are two inertial links The difference between the forward gain connected, T1 and T2 are the time constants of the inertia link.

[0056] The total transfer function of the linear tracking differentiator is as follows:

[0057]

[0058] Where y represents V err The first approximate differential of ; Approximately replace s; T1 and T2 are the time constants of the two inertia links respectively.

[0059] In order to facilitate processor programming, it is necessary to discretize formula (4) and convert the noise-contaminated residual voltage V err (k)= err (k)+ n Substituting (t) into the discretized y expression, we get:

[0060]

[0061] Where k is a time series; x1 and x2 are state variables in the discrete process; V n (t) is the noise signal superimposed on the residual voltage; h is the sampling time; the noise amplification of the approximate differential signal is given by The noise suppression effect can be enhanced by reducing the sampling time h or increasing the time constants T1 and T2 of the inertia link;

[0062] The method provided by this application ( Figure 4 The red and purple solid lines) improve the response speed of the electrostatic accelerometer compared to the traditional measurement method (blue solid line). At the same time, in the technical implementation process of the method provided in this application, it is proposed to use a linear tracking differentiator to improve the noise suppression capability.

[0063] In summary, in order to improve the measurement speed of the electrostatic accelerometer, this application adds a data fusion processing module on the basis of the traditional electrostatic accelerometer, and performs correlation fusion processing on the residual voltage data and the feedback voltage data, thereby compensating for the input acceleration measurement error term related to the relative position x of the inspection mass and the plate frame. The measurement speed of the accelerometer is improved. At the same time, it is proposed to use a linear tracking differentiator to realize the secondary differential of the residual voltage S 2 , thereby effectively reducing the noise interference in the process of implementing the data fusion processing module technology.

[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 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.

[0066] 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. An electrostatic accelerometer, characterized in that: include: Sensitive probe, measurement control module and data processing module; One end of the sensitive probe is connected to the measurement control module; The measurement control module is connected to the data processing module; The measurement control module is used to collect the displacement of the inspection mass in the sensitive probe, convert the displacement signal into a feedback voltage signal and apply it to the capacitor plate in the sensitive probe to generate an electrostatic force; the data processing module is used to collect the feedback voltage signal in the measurement control module and the residual voltage related to the inspection mass displacement and perform analog-to-digital conversion and then fuse them, compensate for the input acceleration measurement error term related to the relative position, and extract the measurement result of the external input acceleration; The relative position is the relative position between the inspection mass and the capacitor plate.

2. The electrostatic accelerometer according to claim 1, characterized in that: The measurement control module includes: a capacitive displacement sensing circuit, a controller and a feedback actuator; The input end of the capacitive displacement sensing circuit is connected to the capacitive plate in the sensitive probe, and the output end thereof is connected to the controller; the input end of the feedback actuator is connected to the controller, and the output end thereof is connected to the capacitive plate; The test mass is used to generate displacement relative to the equilibrium position under the action of external interference force; the capacitive displacement sensing circuit is used to measure the position of the test mass in the capacitor plate and convert the displacement signal into a voltage signal; the controller is used to convert the displacement signal into a feedback voltage and transmit it to the feedback actuator; the feedback actuator is used to apply the feedback voltage obtained by the controller to the capacitor plate to generate electrostatic force.

3. The electrostatic accelerometer according to claim 2, characterized in that: The data processing module includes a first analog-to-digital converter, a second analog-to-digital converter and a data fusion processor; The input end of the first analog-to-digital converter is connected to the capacitive displacement sensing circuit, and the output end thereof is connected to the data fusion processor; the input end of the second analog-to-digital converter is connected to the output end of the feedback actuator, and the output end thereof is connected to the data fusion processor; The first analog-to-digital converter and the second analog-to-digital converter are used to convert the residual voltage signal and the feedback voltage signal from analog signals into digital signals respectively; the data fusion processor is used to fuse the residual voltage signal and the feedback voltage signal of the digital signal to extract the measurement result of the accelerometer.

4. The electrostatic accelerometer according to claim 2 or 3, characterized in that: The measurement result expression of external input acceleration is: Among them, a mea Represents the measurement result of external input acceleration; H sx is the capacitance sensitivity; H sc is the transfer function of the capacitive displacement sensing circuit; V err is the residual voltage; s 2 For the residual voltage V err The second derivative of is the electrostatic negative stiffness characterized by angular frequency; H a is the feedback actuator transfer function; V f is the feedback voltage.

5. The electrostatic accelerometer according to claim 4, characterized in that: A linear tracking differentiator is set in the data fusion processor to obtain a first differential expression of the residual voltage, so as to calculate the residual voltage V err The second derivative of The transfer function of the linear tracking differentiator is: Where y represents V err The first differential of Instead of s; T1 and T2 are the time constants of the two inertial links respectively; among them, the linear tracking differentiator consists of two inertial links The difference between the forward gain Connected.

6. A method for acquiring acceleration based on the electrostatic accelerometer according to claim 1, characterized in that: The following steps are involved: The displacement of the inspection mass in the sensitive probe is collected, and the displacement signal is converted into a feedback voltage signal and applied to the capacitor plate in the sensitive probe to generate an electrostatic force; The feedback voltage signal and the residual voltage related to the displacement of the inspection mass are collected and fused after analog-to-digital conversion, the input acceleration measurement error term related to the relative position is compensated, and the measurement result of the external input acceleration is extracted; Here, the relative position is the relative position between the test mass and the capacitor plates.

7. The acceleration acquisition method according to claim 6, characterized in that: The measurement result expression of external input acceleration is: Among them, a mea Represents the measurement result of external input acceleration; H sx is the capacitance sensitivity; H sc is the transfer function of the capacitive displacement sensing circuit; V err is the residual voltage; s 2 For the residual voltage V err The second derivative of is the electrostatic negative stiffness characterized by angular frequency; H a is the feedback actuator transfer function; V f is the feedback voltage.

8. The acceleration acquisition method according to claim 7, characterized in that: A linear tracking differentiator is used to obtain the first differential expression of the residual voltage. The transfer function of the linear tracking differentiator is: Where y represents V err The first differential of Instead of s; T1 and T2 are the time constants of the two inertial links respectively; among them, the linear tracking differentiator consists of two inertial links The difference between the forward gain Connected.

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