Method for reverse calibration of the quality of the inspection based on capacitive sensing

Abstract

The application relates to the field of electronic information technology, in particular to a quality inspection reverse calibration method based on a capacitance sensing circuit, wherein the capacitance sensing circuit inputs an excitation voltage to a calibrated quality inspection simulator, and reads an output voltage value in the capacitance sensing circuit to obtain a circuit gain of the capacitance sensing circuit; the quality inspection is placed in an electrode cage, so that the quality inspection is located at a central position of the electrode cage; the capacitance sensing circuit is controlled to input the excitation voltage to the quality inspection, and an output voltage value of the electrode cage is read in the capacitance sensing circuit; according to the circuit gain and the output voltage value, an input tolerance of the capacitance sensing circuit is obtained; the posture of the electrode cage is adjusted, so that the electrode cage and the quality inspection have a relative distance change, a relative distance is obtained, and a calibration relationship between the capacitance formed between the quality inspection and the electrode cage and the capacitance size is obtained. The application takes the capacitance sensing circuit as a standard to reversely calibrate the quality inspection, reduces measurement error and is simple to operate.

Description

Technical Field

[0001] This invention belongs to the field of electronic information technology, and in particular relates to a reverse calibration method for inspection quality based on capacitance sensing. Background Technology

[0002] In space gravitational wave detection, capacitive sensing is the primary method for measuring changes in the position of the test mass in inertial sensors. Before testing the performance of the capacitive sensing circuit, it is necessary to determine the magnitude of the capacitance formed by the test mass and the sensing electrodes in at least one of the X, Y, or Z directions. This is a prerequisite for verifying the performance of the capacitive sensing circuit and for calibrating the distance between the test mass and the sensing electrodes, the capacitance size, and the output of the capacitive sensing circuit. Only by calibrating the system and clarifying the correspondence between test mass displacement, capacitance, and output can the position of the test mass be decoupled.

[0003] Currently, the commonly used methods for determining the capacitance of the inspection mass and electrode cage are modeling calculation and direct measurement. The modeling calculation method calculates the capacitance by modeling the inspection mass and electrode cage, using the capacitance calculation formula for a parallel-plate capacitor, and substituting the structural parameters of the sensing electrodes into the model. However, due to factors such as the surface finish of the inspection mass, the coating process, and the parallelism of the plates on the electrode cage, there will be an uncompensated error between the ideal calculation result obtained from the modeling calculation and the actual capacitance.

[0004] The direct measurement method measures capacitance using a measuring instrument. Currently, the AH2700 capacitance meter is a commonly used, high-precision capacitance measuring instrument in industry, achieving an accuracy of 0.8af, which meets measurement requirements. However, this method introduces new problems. Unlike traditional parallel-plate capacitor configurations, the excitation signal is injected into the excitation electrode of the electrode cage and then electrostatically coupled to the test mass. The voltage coupled to the test mass is unknown, meaning there is an unknown attenuation coefficient between the two voltages. Therefore, a further optimization of this method involves leading a metal wire from the test mass to connect the capacitance meter's excitation input to the test mass. This method avoids the voltage attenuation coefficient problem. However, due to system complexity, when testing a single capacitor, the coupling of other parasitic capacitances can cause significant discrepancies between the measurement results and the actual situation. Furthermore, as a precision instrument, the capacitance meter requires cable switching and signal shielding. The test object has extremely high precision; even cable bending can cause capacitance changes that affect the results. Multiple cable replacements are necessary during testing, significantly increasing system complexity. Summary of the Invention

[0005] In view of this, the present invention aims to provide a reverse calibration method for inspection quality based on capacitance sensing. By using a standard transfer, the capacitance sensing circuit is used as a standard reverse calibration suspension structure for inspection quality. Compared with direct measurement using a capacitance meter, this method improves calibration efficiency, is simple to operate, and is easy to implement.

[0006] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0007] A reverse calibration method for inspection quality based on capacitive sensing, comprising:

[0008] S1: The capacitive sensing circuit inputs the excitation voltage to the calibrated inspection quality simulator and reads the output voltage value in the capacitive sensing circuit to obtain the circuit gain of the capacitive sensing circuit.

[0009] S2: Place the inspection mass in the electrode cage so that the inspection mass is located at the center of the electrode cage;

[0010] S3: Control the capacitive sensing circuit in step S1 to input the same excitation voltage as in step S1 to the inspection quality in step S2, and read the output voltage value of the electrode cage in step S2 in the capacitive sensing circuit.

[0011] S4: Based on the circuit gain in step S1 and the output voltage value obtained in step S3, obtain the input tolerance of the capacitive sensing circuit.

[0012] S5: Adjust the posture of the electrode cage to change the relative distance between the electrode cage and the inspection quality.

[0013] S6: Repeat steps S3~S5 to obtain the input tolerance under different relative distances, and then obtain the calibration relationship between the relative distance, the inspection quality and the capacitance formed between the electrode cages.

[0014] Furthermore, the capacitance sensing circuit includes: an excitation generating circuit that outputs an excitation voltage; and a capacitance sensing readout circuit for reading the output voltage value.

[0015] Furthermore, in step S1, a capacitance meter is used to calibrate the inspection quality simulator, which is a capacitor composed of two sets of parallel plates.

[0016] Furthermore, in step S1, the circuit gain is obtained using the following formula:

[0017] ;

[0018] Where G represents the circuit gain, C1 represents the tolerance of the test quality simulator, and V1 represents the output voltage value of the test quality simulator after being excited by the excitation voltage.

[0019] Furthermore, in step S2, both the electrode cage and the inspection mass are hexahedral structures; the two faces of the electrode cage in the X direction each include two sensing electrodes; the two faces of the electrode cage in the Y direction each include two sensing electrodes and one excitation electrode, with the excitation electrode placed between the two sensing electrodes; the two faces of the electrode cage in the Z direction each include two sensing electrodes and two excitation electrodes, with the two excitation electrodes placed between the two sensing electrodes, and the two excitation electrodes located on a straight line.

[0020] Furthermore, in step S4, the input tolerance of the capacitive sensing circuit is obtained using the following formula:

[0021] ;

[0022] Where C2 represents the input tolerance of the capacitive sensing circuit, V2 represents the output voltage value of the electrode cage after the quality is excited by the excitation voltage, and G represents the circuit gain.

[0023] Furthermore, in step S5, the orientation of the electrode cage is adjusted so that the distance between the sensing electrode in the electrode cage and the inspection quality changes.

[0024] Furthermore, in step S6, steps S3 to S5 are repeated to obtain the input tolerance of the capacitive sensing circuit under the distance between each sensing electrode and the inspection mass, and to obtain the calibration relationship between the distance between the sensing electrode and the inspection mass and the capacitance between the inspection mass and the sensing electrode.

[0025] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0026] The present invention presents a reverse calibration method for inspection quality based on capacitance sensing. This method, grounded in the concept of standard transfer, offers advantages such as simple operation, ease of implementation, and accurate results. Specifically, the invention proposes a method for reverse calibration of the capacitance between the inspection quality and the sensing electrodes in an inertial sensor using a capacitance sensing circuit. This method simplifies the analysis process by incorporating various parasitic capacitances during the testing process into the results, directly obtaining the relationship between tolerance and output voltage. Furthermore, the invention transforms the test object of the capacitance meter by replacing it with a simpler inspection quality simulator. This avoids the additional unpredictable interference introduced to the measuring instrument by the complexity of the inspection quality suspension structure, reducing measurement errors and simplifying the tedious and repetitive measurement process. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1A schematic flowchart of the reverse calibration method for inspection quality based on capacitive sensing as described in the embodiments of the present invention;

[0029] Figure 2 A schematic diagram of the implementation circuit of the reverse calibration method for inspection quality based on capacitive sensing described in the embodiment of the present invention;

[0030] Figure 3 A schematic diagram of the capacitive sensing circuit described in an embodiment of the present invention;

[0031] Figure 4 A three-dimensional structural schematic diagram of the electrode cage described in an embodiment of the present invention;

[0032] Figure 5 (a) A schematic diagram of the electrode cage in the X direction according to an embodiment of the present invention;

[0033] Figure 5 (b) A schematic diagram of the electrode cage in the Y direction according to an embodiment of the present invention;

[0034] Figure 5 (c) is a schematic diagram of the electrode cage in the Z direction according to an embodiment of the present invention.

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Capacitive sensing circuit; 2. Quality inspection; 3. Electrode cage; 4. Sensing electrode; 5. Excitation electrode; 6. Wire. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0038] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] like Figure 1 and Figure 2 As shown in the embodiment of the present invention, the reverse calibration method for inspection quality based on capacitive sensing includes:

[0043] S1: The capacitive sensing circuit 1 inputs the excitation voltage to the calibrated inspection quality simulator and reads the output voltage value in the capacitive sensing circuit 1 to obtain the circuit gain of the capacitive sensing circuit 1.

[0044] In some embodiments, a capacitance meter is used to calibrate an inspection quality simulator, which is a capacitor composed of two sets of parallel plates. The capacitance meter is a high-precision electronic device for measuring capacitance values. It outputs an excitation signal through a BNC connector at one end and receives signals through another BNC connector at the other. In this embodiment, during calibration, the excitation input and capacitance output terminals of the inspection quality simulator are connected respectively, and the capacitance meter test parameters are set to read the capacitance value being tested. Furthermore, in this embodiment, each set of parallel plates includes three parallel plates arranged side-by-side. The middle plate and the left plate form one capacitor, and the middle plate and the right plate form another capacitor. The middle plate is a common excitation electrode used for inputting the excitation signal, while the left and right plates are capacitance signal output electrodes.

[0045] This invention employs a standard air capacitor-based inspection quality simulator, which has a simple configuration consisting of two sets of parallel plate capacitors. This invention uses a capacitance meter as a standard to calibrate the inspection quality simulator, achieving standard transfer. Compared to suspended inspection quality simulators, there is no secondary coupling voltage division of the excitation electrodes, and no extra parasitic capacitance is generated. The test results are accurate, and the capacitance meter is easy to calibrate.

[0046] In some embodiments, the capacitance sensing circuit 1 includes an excitation generating circuit and a capacitance sensing readout circuit. The excitation generating circuit outputs an excitation voltage, and the capacitance sensing readout circuit reads the output voltage value. Understandably, the excitation generating circuit inputs an excitation voltage to the inspection quality simulator, and the capacitance sensing readout circuit senses the output voltage value of the inspection quality simulator.

[0047] In this embodiment of the invention, the capacitive sensing circuit 1 is as follows: Figure 3 As shown, the excitation generation circuit generates a stable 100kHz sinusoidal excitation signal as a carrier signal, which is applied to the excitation electrode of the capacitor under test. The capacitance sensing readout circuit includes a transformer, preamplifier, signal conditioning, demodulation, and analog-to-digital converter, which converts the capacitance signal into a voltage signal. After passing through the capacitor, the excitation signal is input to the capacitance sensing readout circuit, which processes and demodulates the signal to obtain a voltage signal corresponding to the capacitance value.

[0048] The circuit gain is obtained using the following formula:

[0049] ;

[0050] Where G represents the circuit gain, and V1 represents the output voltage value of the quality simulator after being excited by the excitation voltage.

[0051] Then, using the capacitive sensing circuit 1 as a standard, the tolerance between the inspection quality 2 and the electrode cage 3 is calibrated in reverse.

[0052] S2: Place the inspection mass 2 in the electrode cage 3 so that the inspection mass 2 is located at the center of the electrode cage 3.

[0053] In some embodiments, both the electrode cage 3 and the inspection mass 2 are hexahedral structures, and the structure of the electrode cage 3 is as follows: Figure 4 and Figure 5 As shown, each of the two faces of the electrode cage 3 in the X direction includes two sensing electrodes 4; each of the two faces of the electrode cage 3 in the Y direction includes two sensing electrodes 4 and one excitation electrode 5, with the excitation electrode 5 positioned between the two sensing electrodes 4; each of the two faces of the electrode cage 3 in the Z direction includes two sensing electrodes 4 and two excitation electrodes 5, with the two excitation electrodes 5 positioned between the two sensing electrodes 4, and the two excitation electrodes 5 lying in a straight line. It can be understood that the six faces of the inspection mass 2 and the sensing electrodes 4 on the electrode cage 3 will form 12 capacitors.

[0054] In this embodiment of the invention, a metal rod is used instead of a metal suspension wire to form a rigid, insulated connection with the inspection mass 2, keeping the inspection mass 2 at a fixed position at the center of the electrode cage 3. A wire 6 is led out from the inspection mass 2; to reduce impedance and increase conductivity, the wire 6 is preferably made of gold wire. Furthermore, in this embodiment, the electrode cage 3 is insulated and placed on a six-axis positioning stage. By adjusting the six-axis positioning stage, the relative position of the electrode cage 3 and the inspection mass 2 is changed, keeping the inspection mass 2 at a fixed position at the center of the electrode cage 3.

[0055] S3: The capacitive sensing circuit 1 in control step S1 inputs the same excitation voltage as in step S1 to the inspection quality 2 in step S2, and reads the output voltage value of the electrode cage 3 in step S2 in the capacitive sensing circuit 1.

[0056] In this embodiment of the invention, the excitation generating circuit in the capacitive sensing circuit 1 injects an excitation voltage into the inspection mass 2 through the wire 6, and the capacitive sensing readout circuit is connected to the electrode cage 3 to read the output voltage value of the electrode cage 3.

[0057] S4: Based on the circuit gain in step S1 and the output voltage value obtained in step S3, the input tolerance of the capacitive sensing circuit 1 is obtained.

[0058] Since the circuit gain of the capacitive sensing circuit 1 is only related to the parameters of the capacitive sensing circuit 1, the circuit gain is a fixed value when the capacitive sensing circuit 1 remains unchanged. Therefore, under the same capacitive sensing circuit 1 and precise tuning, the circuit gain G remains unchanged. Therefore, the capacitive sensing circuit 1 is used as a standard to reverse calibrate and test the tolerance between the mass 2 and the sensing electrode 4.

[0059] In some embodiments, the input tolerance of the capacitive sensing circuit 1 is obtained by the following formula:

[0060] ;

[0061] Where C2 represents the input tolerance of the capacitive sensing circuit 1, and V2 represents the output voltage value of the electrode cage 3 after the inspection mass 2 is excited by the excitation voltage.

[0062] S5: Adjust the orientation of the electrode cage 3 to change the relative distance between the electrode cage 3 and the inspection mass 2. Specifically, keep the orientation of the inspection mass 2 fixed, and adjust the orientation of the electrode cage 3 to change the distance between the sensing electrode 4 in the electrode cage 3 and the inspection mass 2. In this embodiment of the invention,

[0063] The inspection mass 2 is suspended by a metal rod, and its posture is kept fixed. The posture of the electrode cage 3 is adjusted using a six-axis positioning table, so that the distance between the sensing electrode 4 in the electrode cage 3 and the inspection mass 2 changes.

[0064] S6: Repeat steps S3~S5 to obtain the input tolerance under different relative distances, and then obtain the calibration relationship between the relative distance and the capacitance formed between the inspection quality 2 and the electrode cage 3.

[0065] Specifically, in step S6, steps S3 to S5 are repeated to obtain the voltage of the capacitor readout circuit at different relative distances. The input tolerance at different relative distances can be calculated, and thus the capacitance between the inspection mass 2 and the electrode cage 3 can be obtained. The distance is obtained through a six-axis positioning stage and is a known quantity controlled manually. The capacitance corresponding to different distances is recorded, and the calibration relationship (i.e., the calibration relationship between the distance between the sensing electrode 4 and the inspection mass 2, and the capacitance between the inspection mass 2 and the sensing electrode 4) can be obtained through fitting.

[0066] Understandably, the capacitance value is related to the distance between the two electrodes of the capacitor. Therefore, when the distance between the sensing electrode 4 and the inspection mass 2 changes, the 12 capacitors formed by the inspection mass 2 and the 12 sensing electrodes 4 also change. Thus, by adjusting the posture of the electrode cage 3 each time, the calibration relationship between the distance between the 12 sensing electrodes 4 and the inspection mass 2 and the corresponding 12 capacitors can be obtained. Furthermore, by repeating steps S3~S5 N times, N×12 sets of calibration relationships can be obtained.

[0067] This invention uses a standard transfer mechanism, employing the capacitance sensing circuit 1 as a standard reverse calibration inspection quality suspension structure. The final test result incorporates the effects of the surface finish, coating process, and parallelism of the upper plates of the electrode cage 3 on the inspection quality 2. Compared to direct measurement using a capacitance meter, which requires frequent wiring changes, capacitance testing, and tolerance calculation, using the capacitance sensing circuit 1 directly calibrates the tolerance, reducing the amount of work by half and improving calibration efficiency. It is also simple and easy to implement. Most importantly, this invention can implicitly include errors such as parasitic capacitance between test cables, between sensing electrodes 4, and between the electrode cage 3 and ground in the results, simplifying the analysis process and improving test accuracy.

[0068] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0069] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A reverse calibration method for inspection quality based on capacitive sensing, characterized in that, include: S1: The capacitive sensing circuit inputs the excitation voltage to the calibrated inspection quality simulator and reads the output voltage value in the capacitive sensing circuit to obtain the circuit gain of the capacitive sensing circuit. S2: Place the inspection mass in the electrode cage so that the inspection mass is located at the center of the electrode cage; S3: Control the capacitive sensing circuit in step S1 to input the same excitation voltage as in step S1 to the inspection quality in step S2, and read the output voltage value of the electrode cage in step S2 in the capacitive sensing circuit. S4: Based on the circuit gain in step S1 and the output voltage value obtained in step S3, obtain the input tolerance of the capacitive sensing circuit. S5: Adjust the posture of the electrode cage to change the relative distance between the electrode cage and the inspection quality. S6: Repeat steps S3~S5 to obtain the input tolerance under different relative distances, and then obtain the calibration relationship between the relative distance, the inspection quality and the capacitance formed between the electrode cages.

2. The reverse calibration method for inspection quality based on capacitive sensing according to claim 1, characterized in that, The capacitive sensing circuit includes: Excitation generation circuit, used to output excitation voltage; The capacitive sensing readout circuit is used to read the output voltage value.

3. The reverse calibration method for inspection quality based on capacitive sensing according to claim 1, characterized in that, In step S1, a capacitance meter is used to calibrate the inspection quality simulator, which is a capacitor consisting of two sets of parallel plates.

4. The reverse calibration method for inspection quality based on capacitive sensing according to claim 1, characterized in that, In step S1, the circuit gain is obtained using the following formula: ； Where G represents the circuit gain, C1 represents the tolerance of the test quality simulator, and V1 represents the output voltage value of the test quality simulator after being excited by the excitation voltage.

5. The reverse calibration method for inspection quality based on capacitive sensing according to claim 1, characterized in that, In step S2, both the electrode cage and the inspection mass are hexahedral structures. The electrode cage has two sensing electrodes on each of its two faces in the X direction; two sensing electrodes and one excitation electrode on each of its two faces in the Y direction, with the excitation electrode placed between the two sensing electrodes; and two sensing electrodes and two excitation electrodes on each of its two faces in the Z direction, with the two excitation electrodes placed between the two sensing electrodes and the two excitation electrodes located on a straight line.

6. The reverse calibration method for inspection quality based on capacitive sensing according to claim 1, characterized in that, In step S4, the input tolerance of the capacitive sensing circuit is obtained using the following formula: ； Where C2 represents the input tolerance of the capacitive sensing circuit, V2 represents the output voltage value of the electrode cage after the quality is excited by the excitation voltage, and G represents the circuit gain.

7. The reverse calibration method for inspection quality based on capacitive sensing according to claim 5, characterized in that, In step S5, the orientation of the electrode cage is adjusted so that the distance between the sensing electrode in the electrode cage and the inspection quality changes.

8. The reverse calibration method for inspection quality based on capacitive sensing according to claim 7, characterized in that, In step S6, steps S3 to S5 are repeated to obtain the input tolerance of the capacitive sensing circuit under the distance between each sensing electrode and the inspection mass, and to obtain the calibration relationship between the distance between the sensing electrode and the inspection mass and the capacitance between the inspection mass and the sensing electrode.

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