Phase Synchronization Monitoring and Adjustment Method for Multi-Channel Excitation Signals

Abstract

The present invention belongs to the technical field of space inertial sensors, and particularly relates to a method for phase synchronization monitoring and adjustment of multi-channel excitation signals. It includes: S1: Build a test platform, which includes a sensitive probe and capacitive sensing electronics; S2: Make the center of the electrode cage have a small displacement in the X-axis direction of the detection plate relative to the center of the detection plate, and the capacitive sensing electronics transmits different excitation signals to each excitation plate; S3: Iteratively adjust the initial phases of the excitation signals based on an optimization algorithm; S4: When the induced voltages output by the measured induced plate pairs satisfy the iteration stop condition after adjusting the initial phases twice in succession, the phase synchronization monitoring and adjustment of the multi-channel excitation signals are completed. The present invention can offset the influence of factors such as the sensitive probe structure design and line delay of the capacitive displacement sensor on the phase delay of the multi-channel excitation signals, and improve the sensitivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of space inertial sensors, and in particular relates to a method for monitoring and adjusting the phase synchronization of multi-channel excitation signals. Background Art

[0002] Differential capacitance displacement sensors are widely used in fields such as aerospace, especially in the measurement of weak forces, such as inertial sensors, electrostatic accelerometers, and electrostatic torsion balances. A differential capacitance displacement sensor is a non-contact sensor. Its basic principle is to form multiple differential capacitances by using a detection electrode plate and an induction electrode plate. An AC excitation signal is applied to the detection electrode plate, and the voltage of the induction electrode plate is read through a bridge circuit and a demodulation circuit, thereby converting the capacitance signal into a voltage signal.

[0003] Due to special design requirements or installation conditions, the excitation signal of the differential capacitance displacement sensor cannot be directly applied to the detection electrode plate, and the excitation signal needs to be indirectly applied through an excitation electrode. At the same time, considering the system symmetry and excitation injection efficiency issues, multiple excitation signals need to be externally applied.

[0004] However, the phase delays caused by factors such as line delay, electronics, and structural design differences make the phases of the excitation signals not aligned, resulting in the amplitude of the composite signal acting on the detection electrode plate not reaching the designed maximum value, causing the capacitance sensing scale factor to be less than the theoretical value, and further reducing the sensitivity of capacitance sensing.

[0005] In the research field of space inertial sensors, Zhu Sheng from Huazhong University of Science and Technology proposed an online measurement and correction scheme for the amplitude and phase of four-channel injection excitation signals based on FFT in his doctoral thesis "Research on Capacitance Extraction and Injection Optimization of Sensitive Probes for High-Precision Capacitance Displacement Sensors" published in 2023, and carried out simulations and related experiments. This research only focuses on the electronics single machine, without connecting the sensitive probe, without considering the influence of line delay and the sensitive probe structure on the phase of the excitation signal acting on the detection electrode, and other research has not considered this problem, directly theoretically calculating the capacitance sensing scale factor.

[0006] The Chinese invention patent named "Method for Measuring Amplitude-Phase Frequency Characteristics and De-embedding of Multi-channel Capacitance Displacement Sensing Circuit" (publication number: CN117368583A, publication date: January 9, 2024) can remove the influence of the calibration auxiliary test unit on the measurement result. The results obtained by this method can improve the actual transmission characteristics of each displacement sensing channel and improve the overall performance of the circuit. The problem it considers is to solve the problem of testing the frequency characteristics of capacitance sensing signals between multiple induction electrode plates, rather than the phase difference of multiple excitation signals. Summary of the Invention

[0007] In view of this, the present invention aims to provide a method for phase synchronization monitoring and adjustment of multi-channel excitation signals, so as to solve the problem of phase delay caused by factors such as line delay, differences in electronics and structural design in the prior art, resulting in misalignment of the phases of each excitation signal, the amplitude of the combined signal acting on the detection plate not reaching the designed maximum value, and the capacitance sensing scale factor being less than the theoretical value, thereby reducing the sensitivity of capacitance sensing. The present invention optimizes the algorithm to adjust the initial phase of the multi-channel excitation signals, cancels the influence of factors such as the sensitive probe structure design and line delay of the capacitance displacement sensor on the phase delay of the multi-channel excitation signals, and thereby increases the scale factor of the capacitance displacement sensor and improves the sensitivity.

[0008] To achieve the above object, the technical solution of the present invention is realized as follows:

[0009] A method for phase synchronization monitoring and adjustment of multi-channel excitation signals, which is used to realize the phase synchronization monitoring and adjustment of the multi-channel excitation signals of a capacitance displacement sensor, specifically includes the following steps:

[0010] S1: Build a test platform, which includes a sensitive probe and capacitance sensing electronics;

[0011] The sensitive probe includes an electrode cage, a six-legged adjustment platform, a plurality of excitation plates and a plurality of induction plates fixed to the electrode cage in an insulating manner, and a detection plate located inside the electrode cage. The six-legged adjustment platform drives the electrode cage to move relative to the detection plate in six degrees of freedom;

[0012] S2: In a vacuum environment, move the electrode cage along the X-axis direction of the detection plate, so that the center of the electrode cage has a small displacement relative to the center of the detection plate in the X-axis direction of the detection plate. The capacitance sensing electronics transmits different excitation signals to each excitation plate, so that the detection plate and each pair of induction plates generate induced voltages. The relationship between the amplitudes of the induced voltages output by each pair of induction plates and the induced voltage output by the detection plate is:

[0013] ;

[0014] ;

[0015] Wherein, is the induced voltage output by each pair of induction plates, is the gain of the capacitance sensing circuit of the capacitance sensing electronics, is the amplitude of the induced voltage output by the detection plate, is the phase shift caused by the line delay of the i-th excitation signal and the sensitive probe structure design, is the voltage division ratio from the i-th excitation plate to the detection plate, is the amplitude of the i-th excitation signal, is the initial phase of the i-th excitation signal, n = 6;

[0016] S3: Arbitrarily select an induction electrode pair in the X-axis direction of the detection electrode plate as the to-be-tested induction electrode pair, and iteratively adjust the initial phases of each excitation signal based on the optimization algorithm, so that the initial phases of two adjacent adjustments satisfy the following formula:

[0017] ;

[0018] where, is the initial phase of the i-th excitation signal during the -th adjustment, is the initial phase of the i-th excitation signal during the -th adjustment, is the phase shift caused by the line delay of the i-th excitation signal and the sensitive probe structure design, is the learning rate, is the induced voltage output by the to-be-tested induction electrode pair;

[0019] S4: Use capacitive sensing electronics to measure the induced voltage output by the to-be-tested induction electrode pair in real time. When the induced voltages output by the to-be-tested induction electrode pair measured after two adjacent adjustments of the initial phase satisfy the following formula, stop the iteration and complete the phase synchronization monitoring and adjustment of the multi-channel excitation signals:

[0020] ;

[0021] where, is the induced voltage output by the to-be-tested induction electrode pair during the -th adjustment, is the induced voltage output by the to-be-tested induction electrode pair during the -th adjustment, is the iteration stop parameter.

[0022] Furthermore, in step S1, the capacitive sensing electronics includes a capacitive sensing circuit and a data processing device connected in sequence. The capacitive sensing circuit is used to transmit excitation signals to each excitation electrode plate and measure the induced voltage output by the to-be-tested induction electrode pair, and the data processing device is used to run the optimization algorithm;

[0023] The sensitive probe further includes a fixing device and a vacuum chamber. Among them, the fixing device, the electrode cage, the six-legged adjustment platform, several excitation electrode plates, several induction electrode plates, the electrode cage, and the detection electrode plate are all placed in the vacuum chamber;

[0024] The fixing device suspends the detection electrode plate inside the electrode cage. A number of induction electrode plates are evenly distributed around the detection electrode plate on the electrode cage in an insulating form. A number of excitation electrode plates are symmetrically arranged on the electrode cage along the Y-axis direction and the Z-axis direction of the detection electrode plate in an insulating form.

[0025] Further, the detection electrode plate is a cube, the electrode cage is a cube with a hollow interior, and the capacitance sensing circuit is connected to the to-be-detected induction electrode plate and the excitation electrode plate respectively through cables.

[0026] Further, in step S2, the frequencies of different excitation signals are the same, and the initial phases are different.

[0027] Further, in step S2, the induced voltage output by the detection electrode plate has the following expression:

[0028] ;

[0029] where is the phase shift caused by the line delay of the i-th excitation signal and the sensitive probe structure design, is the voltage division ratio from the i-th excitation electrode plate to the detection electrode plate, is the amplitude of the i-th excitation signal, is the initial phase of the i-th excitation signal, is the angular frequency of the excitation signal, and n = 6.

[0030] Further, in step S2, the smaller displacement amount takes any value between 10 microns and 20 microns.

[0031] Further, in step S3, the optimization algorithm is the gradient ascent algorithm, Newton's method, or the neural network method.

[0032] Further, in step S3:

[0033] .

[0034] Further, in step S4, the output voltage of the to-be-detected induction electrode plate pair is:

[0035] ;

[0036] where represents the gain of the capacitance sensing circuit, represents the input of the differential capacitance of the induction electrode plate pair, K is the scale factor, is the amplitude of the i-th excitation signal, is the voltage division ratio from the i-th excitation electrode plate to the detection electrode plate.

[0037] Compared with the prior art, the invention can achieve the following beneficial effects:

[0038] (1) The phase synchronization monitoring and adjustment method of the multi-channel excitation signal created by the present invention takes into account the influence of factors such as sensitive probe structure design and line delay on the phase delay of the multi-channel excitation signal. Compared with existing research, it is closer to practical application and fills the gap in the research field.

[0039] (2) The phase synchronization monitoring and adjustment method of the multi-channel excitation signal created by the present invention does not directly measure the phase delay, but changes the initial phase of the excitation signal by fixing the detection electrode, and finds the maximum value of the capacitive sensor output signal to offset the influence of the line delay, thereby achieving the purpose of synchronizing the phase of the excitation signal, and finally improving the sensitivity of the capacitive sensor measurement. The present invention is simple and efficient, and does not require the addition of additional monitoring equipment.

[0040] (3) The phase synchronization monitoring and adjustment method of the multi-channel excitation signal created by the present invention takes into account the characteristic that the excitation plate is not distributed in the x-axis direction in the structural design of the sensitive probe, and selects the x-axis capacitive sensing output voltage signal as the target signal, thereby reducing the influence of the excitation plate on the sensing plate and improving the accuracy of the test. At the same time, the slight position offset in the x-axis direction has little effect on the capacitance distribution of the excitation plate in the sensitive probe, so that the voltage divider ratio from the voltage applied on the excitation plate to the detection plate remains basically unchanged, thereby increasing the applicability and accuracy of the test method. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0042] Figure 1 A schematic diagram of the structure of a capacitive displacement sensor according to an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the distribution of electrode plates of the sensitive probe according to an embodiment of the present invention;

[0044] Figure 3 A flow chart of a method for synchronously monitoring and adjusting phases of multi-channel excitation signals according to an embodiment of the present invention;

[0045] Figure 4 A phase convergence diagram of each excitation signal described in the embodiment of the present invention;

[0046] Figure 5 The invention creates a convergence diagram of the output voltage of the induction plate to be tested according to the embodiment of the invention.

[0047] Description of the reference numerals in the drawings:

[0048] 1. Electrode cage; 2. Inductive electrode plate; 3. Detection electrode plate; 4. Hexapod adjustment platform; 5. Excitation electrode plate; 6. Fixing device; 7. Vacuum tank; 8. Capacitance sensing circuit; 9. Data processing device. Detailed implementation manners

[0049] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention.

[0050] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0051] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0052] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0053] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0054] As Figure 1As shown in the figure, the test platform (i.e., the capacitive displacement sensor) includes a sensitive probe and capacitive sensing electronics; the sensitive probe includes an electrode cage 1, a six-legged adjustment platform 4, a plurality of excitation plates 5 and a plurality of induction plates 2 fixed to the electrode cage 1 in an insulating manner, a detection plate 3 located inside the electrode cage 1, a fixing device 6 and a vacuum chamber 7. The fixing device 6, the electrode cage 1, the six-legged adjustment platform 4, a plurality of excitation plates 5 (where the plurality mentioned here is greater than 2), a plurality of induction plates 2, the electrode cage 1 and the detection plate 3 are all placed inside the vacuum chamber 7; the fixing device 6 suspends the detection plate 3 inside the electrode cage 1, and a plurality of induction plates 2 are evenly distributed around the detection plate 3 on the electrode cage 1 in an insulating form. A plurality of excitation plates 5 are symmetrically arranged on the electrode cage 1 along the Y-axis direction and the Z-axis direction of the detection plate 3 in an insulating form. The six-legged adjustment platform 4 drives the electrode cage 1 to move relative to the detection plate 3 in six degrees of freedom. The X-axis direction, Y-axis direction and Z-axis direction of the detection plate 3 satisfy the right-hand rule.

[0055] The capacitive sensing electronics includes a capacitive sensing circuit 8 and a data processing device 9 connected in sequence. The capacitive sensing circuit 8 is used to transmit excitation signals to each excitation plate 5 and measure the induced voltage output by the to-be-measured induction plate pair. The data processing device 9 is used to run an optimization algorithm.

[0056] In some embodiments, the detection plate 3 is a cube, the electrode cage 1 is a cube with a hollow interior, and the capacitive sensing circuit 8 is connected to the to-be-measured induction plate and the excitation plates 5 through cables.

[0057] Figure 2 The relative positional relationship among the detection plate 3, the induction plates 2 and the excitation plates 5 in the sensitive probe is shown in the figure. The detection plate 3 is a cube and is located at the center of the sensitive probe; the induction plates 2 are symmetrically distributed around the detection plate 3 and are distributed along the positive and negative directions of the X-axis at equal intervals. The induction plates are distributed along the positive and negative directions of the Y-axis at equal variable intervals. The induction plates are distributed along the positive and negative directions of the Z-axis at equal intervals. The excitation electrodes J are symmetrically distributed relative to the detection plate 3, and the excitation plates are distributed along the positive and negative directions of the Y-axis at equal intervals. The excitation plates are distributed along the positive and negative directions of the Z-axis at equal intervals. .

[0058] As Figure 3 shown in the figure, the multi-channel excitation signal phase synchronization monitoring and adjustment method of the present invention is used to realize the multi-channel excitation signal phase synchronization monitoring and adjustment of a capacitive displacement sensor, and specifically includes the following steps: S1: Build a test platform, and the test platform includes a sensitive probe and capacitive sensing electronics;

[0059] The sensitive probe includes an electrode cage 1, a six-legged adjustment platform 4, a plurality of excitation plates 5 and a plurality of induction plates 2 fixed to the electrode cage 1 in an insulating manner, and a detection plate 3 located inside the electrode cage 1. The six-legged adjustment platform 4 drives the electrode cage 1 to move relative to the detection plate 3 in six degrees of freedom.

[0060] S2: In a vacuum environment, move the electrode cage 1 along the X-axis direction of the detection plate 3 so that there is a small displacement of the center of the electrode cage 1 relative to the center of the detection plate 3 in the X-axis direction of the detection plate 3. The capacitive sensing electronics transmits different excitation signals to each excitation plate 5, causing induced voltages to be generated in both the detection plate 3 and each pair of induction plates. The relationship between the induced voltages output by each pair of induction plates and the amplitude of the induced voltage output by the detection plate 3 is:

[0061] ;

[0062] ;

[0063] Among them, is the induced voltage output by each pair of induction plates, is the gain of the capacitive sensing circuit 8 of the capacitive sensing electronics, is the amplitude of the induced voltage output by the detection plate 3, is the phase shift caused by the line delay of the i-th excitation signal and the sensitive probe structure design, is the voltage division ratio from the i-th excitation plate 5 to the detection plate 3, is the amplitude of the i-th excitation signal, is the initial phase of the i-th excitation signal, n = 6;

[0064] S3: Arbitrarily select a pair of induction plates as the pair of induction plates to be measured in the X-axis direction of the detection plate 3. Based on the optimization algorithm, iteratively adjust the initial phases of each excitation signal so that the initial phases of adjacent two adjustments satisfy the following formula:

[0065] ;

[0066] Among them, is the initial phase of the i-th excitation signal during the -th adjustment, is the initial phase of the i-th excitation signal during the -th adjustment, is the phase shift caused by the line delay of the i-th excitation signal and the sensitive probe structure design, is the learning rate, is the induced voltage output by the pair of induction plates to be measured;

[0067] S4: Use capacitive sensing electronics to measure the induced voltage output by the induced electrode plate to be measured in real time. When the induced voltages output by the induced electrode plate to be measured measured after two adjacent initial phase adjustments satisfy the following formula, stop the iteration and complete the phase synchronization monitoring and adjustment of the multi-channel excitation signals:

[0068] ;

[0069] where, is the induced voltage output by the induced electrode plate to be measured during the th adjustment, is the induced voltage output by the induced electrode plate to be measured during the th adjustment, is the iteration stop parameter.

[0070] It should be noted that in practical applications, it is very difficult for the positions of the centers of the electrode cage 1 and the detection electrode plate 3 to coincide, and there will be an offset during the assembly process. Generally speaking, the smaller displacement is any value between 10 μm and 20 μm.

[0071] In some embodiments, in step S2, the frequencies of different excitation signals are the same, but the initial phases are different.

[0072] It should be noted that the i-th excitation signal is:

[0073] ;

[0074] where, is the amplitude of the i-th excitation signal, is the initial phase (controllable) of the i-th excitation signal, is the signal angular frequency which is a fixed value.

[0075] In some embodiments, the expression of the induced voltage output by the detection electrode plate 3 is:

[0076] ;

[0077] where, is the phase shift caused by the line delay of the i-th excitation signal and the sensitive probe structure design, is the voltage division ratio from the i-th excitation electrode plate 5 to the detection electrode plate 3, and its magnitude is related to the capacitance distribution of the sensitive probe, is the amplitude of the i-th excitation signal, is the initial phase of the i-th excitation signal, is the angular frequency of the excitation signal, n = 6.

[0078] Theoretically, when the initial phase When the following formula is satisfied, the induced voltage on the detection electrode plate 3 is detected has the maximum amplitude:

[0079] ;

[0080] At this time, the amplitude of the induced voltage on the detection electrode plate 3 can be expressed as:

[0081] ;

[0082] At this time, the scale factor of the capacitance sensing circuit 8 is the largest; it is

[0083] ;

[0084] At this time, the output voltage of the capacitance sensing circuit 8 for the induced electrode plate pair to be measured is at most:

[0085] ;

[0086] Among them, represents the gain of the capacitance sensing circuit 8, represents the input of the differential capacitance of the induced electrode plate pair, K is the scale factor, is the amplitude of the i-th excitation signal, is the voltage division ratio from the i-th excitation electrode plate 5 to the detection electrode plate 3.

[0087] It should be noted that considering the influence of measurement noise, the induced voltage output by the induced electrode plate pair to be measured fluctuates. When the induced voltages output by the induced electrode plate pair to be measured before and after satisfy the formula iteration stop parameter, the iteration stops. The iteration stop parameter is related to the output voltage fluctuation of the capacitance sensing circuit 8 and can be set according to specific situations.

[0088] In some embodiments, in step S3, the optimization algorithm is the gradient ascent algorithm, Newton's method or neural network method.

[0089] In the present invention, the detection electrode plate 3 is first fixed to deviate from the center position of the electrode cage 1 by a small displacement, and the output voltage of the capacitive displacement sensor is recorded. An optimization algorithm is designed to adjust the initial phases of the excitation signals of each channel, so that the output voltage of the capacitive displacement sensor is maximized, thereby making the initial phases of the excitation signals cancel the phase delay generated by factors such as line delay, achieving the purpose of synchronizing the phases of the excitation signals, and further making the composite signal acting on the detection electrode plate 3 reach the designed maximum value, ensuring that the capacitive sensing sensitivity is consistent with the designed value. Here, the initial phases of the multi-channel excitation signals are adjusted through an optimization algorithm to cancel the influence of factors such as the structural design of the sensitive probe of the capacitive displacement sensor and line delay on the phase delay of the multi-channel excitation signals, thereby increasing the scale factor of the capacitive displacement sensor and improving the sensitivity.

[0090] The core idea of the present invention is to solve the problem that the sensitivity of the capacitive displacement sensor is lower than the designed value by adjusting the phases of the multi-channel excitation signals in real time. The phase synchronization of the excitation signals mentioned in the present invention does not refer to the phase synchronization when the excitation signals are output from the DA, but the phase synchronization when they act on the detection electrode plate 3.

[0091] Embodiment 1

[0092] The method for synchronously monitoring and adjusting the phases of the multi-channel excitation signals of the capacitive displacement sensor of the present invention is applied to an inertial sensor of a certain model. Taking the capacitive sensing unit of the cube-shaped sensitive probe as an example, the specific embodiments of the present invention are introduced in detail.

[0093] A test platform is built to keep the vacuum chamber 7 in a high-vacuum environment, turn on the temperature control and environmental monitoring (implemented by the vacuum system 7), and control the center of the electrode cage 1 to approach the center of the detection electrode plate 3 through the six-legged adjustment platform 4 and maintain a small offset.

[0094] Considering that there is no excitation electrode plate 5 arranged in the x-axis direction of the detection electrode plate 3, that is, there is no excitation electrode plate 5 arranged in the x-axis direction of the sensitive probe (the sensitive probe is composed of all components in the vacuum chamber 7), only a small offset is maintained in the x-axis direction (the center of the electrode cage 1 relative to the center of the detection electrode plate 3), reducing the influence of the position offset of the detection electrode plate 3 on the capacitance of the excitation electrode plate 5 and reducing the voltage division ratio of the excitation electrode plate voltage caused by the detection electrode plate deviating from the center position. Subsequently, the induction electrode plate 2 in the x-axis direction is also selected to read the voltage data of the capacitive displacement sensor to improve the test accuracy.

[0095] Step 2:

[0096] The capacitive sensing electronics (the combination of the capacitive sensing circuit 8 and the data processing device 9) outputs 6-channel voltage excitation signals acting on the excitation electrode plate 5.

[0097] Each excitation signal has the same frequency and different initial phases. The expression of the excitation signal is:

[0098] ;

[0099] where is the amplitude of the i-th excitation signal, is the initial phase (controllable) of the i-th excitation signal, is the angular frequency of the excitation signal, which is a fixed value, is the i-th excitation signal.

[0100] At this time, the induced voltage on the detection plate 3 obtained by the combined action of each excitation voltage is:

[0101] ;

[0102] where is the phase shift caused by the line delay of the i-th excitation signal and the structural design of the sensitive probe, is the voltage division ratio from the i-th excitation plate 5 to the detection plate 3, and its magnitude is related to the capacitance distribution of the sensitive probe. When the relative position of the detection plate 3 and the electrode cage 1 is fixed, is a fixed value.

[0103] Step 3:

[0104] The capacitive sensing electronics continuously measures the differential capacitive sensing output voltage .

[0105] The output voltage of the capacitive sensing is expressed as:

[0106] ;

[0107] where is the gain of the capacitive sensing circuit 8 corresponding to a pair of sensing plates (the pair of sensing plates to be measured) in the X-axis direction, represents the differential capacitance input of a pair of sensing plates 2 in the X-axis direction.

[0108] Step 4:

[0109] Design an optimization algorithm to iteratively adjust the initial phases of each excitation signal .

[0110] In practical applications, the gradient ascent method can be selected for solution, and the same purpose can also be achieved by using other optimization algorithms.

[0111] Take the partial derivative of the initial phases of each excitation signal and calculate the gradient as follows:

[0112] ;

[0113] Among them, is the input of the differential capacitance of the induction electrode pair.

[0114] Initial phase is updated according to the following rules:

[0115] ;

[0116] Among them, is the learning rate, which controls the amplitude of each update, is the induced voltage corresponding to the current excitation signal, and k is the number of iterations.

[0117] Figure 4 is the phase convergence diagram of each excitation signal. Figure 4 In, the learning rate is selected as 0.05, and the phase offset of each excitation signal is a random value. When the visible iteration exceeds 500 times, the initial phase converges to a fixed value .

[0118] Step 5:

[0119] The capacitive sensing electronics continuously measures the output voltage of the induction electrode 2 , samples the output voltage . When the sampling of the capacitive sensing circuit 8 in the previous and subsequent times satisfies the following formula, the iteration stops, where represents the iteration stop condition, which is related to the output voltage fluctuation of the capacitive sensing circuit 8 and can be set according to specific situations.

[0120] ;

[0121] Figure 5 is the output voltage convergence diagram of the capacitive sensing. Figure 4 In, the stop condition is taken as . After the iteration reaches 200 times, the stop condition is satisfied.

[0122] Considering the fluctuation of the output voltage of the capacitive transmission, a filtering function is designed to filter the output voltage to improve the accuracy of the optimization algorithm. For example, mean filtering is adopted, and the iteration cut-off condition is:

[0123] ;

[0124] Among them, is the mean filtering sliding window length, is the offset within the current mean filter sliding window, and the same effect can be achieved by other similar processing methods.

[0125] Considering that the readout voltage of the capacitive displacement sensor fluctuates due to the influence of various noises, filtering the readout voltage of the capacitive displacement sensor (the output voltage of the sensing electrode plate 2) can achieve better results. Here, the mean filter algorithm is used, and the same effect can be achieved by other filtering algorithms.

[0126] In addition, in the design of the sensitive probe structure of the present invention, considering the characteristic that the excitation electrode plate is not distributed in the x-axis direction, the output voltage signal of the capacitive displacement sensor on the x-axis is selected as the target signal, which reduces the influence of the excitation electrode plate 5 on the sensing electrode plate 2 and improves the test accuracy. If two differential capacitances in the x-axis direction are selected for simultaneous detection, the accuracy of the test results can be improved, but the idea is the same as that of this method.

[0127] At the same time, a small position offset in the x-axis direction has little influence on the capacitance distribution of the excitation electrode plate 5 in the sensitive probe, which makes the voltage division ratio from the voltage applied to the excitation electrode plate 5 to the detection electrode plate 3 basically unchanged, increasing the applicability and accuracy of the test method. If the position offset of the detection electrode plate 3 is changed to measure the voltage division ratio and initial phase at different positions and a lookup table is designed to compensate for the phase, the test effect can also be improved, and the basic idea is the same as that of the present invention.

[0128] It should be understood that various forms of the processes shown above can be used, reordering, adding, or deleting steps. For example, the steps described in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present invention can be achieved, and no limitations are imposed herein.

[0129] The above specific embodiments do not constitute a limitation to the protection scope of the present 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 principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for phase synchronization monitoring and adjustment of multi-channel excitation signals, which is used to realize the phase synchronization monitoring and adjustment of multi-channel excitation signals of a capacitive displacement sensor, and is characterized in that: The specific steps include: S1: Build the test platform, which includes sensitive probes and capacitive sensing electronics; The sensitive probe includes an electrode cage, a six-legged adjustment platform, a plurality of excitation plates and a plurality of induction plates fixed on the electrode cage in an insulated manner, and a detection plate located in the electrode cage, wherein the six-legged adjustment platform drives the electrode cage to move with six degrees of freedom relative to the detection plate; S2: In a vacuum environment, the electrode cage is moved along the X-axis direction of the detection electrode plate, so that the center of the electrode cage has a small displacement in the X-axis direction of the detection electrode plate relative to the center of the detection electrode plate. The capacitive sensing electronics transmits different excitation signals to each excitation electrode plate, so that the detection electrode plate and each induction electrode plate pair generate an induced voltage. The relationship between the amplitude of the induced voltage output by each induction electrode plate pair and the induced voltage output by the detection electrode plate is: ； ； Among them, is the induced voltage output by each pair of induction plates, is the gain of the capacitance sensing circuit of the capacitance sensing electronics, is the amplitude of the induced voltage output by the detection plate, is the phase shift caused by the line delay of the i-th excitation signal and the structural design of the sensitive probe, is the voltage division ratio from the i-th excitation plate to the detection plate, is the amplitude of the i-th excitation signal, is the initial phase of the i-th excitation signal, n = 6, represents the input of the differential capacitance of the pair of induction plates; S3: randomly select a sensing plate pair in the X-axis direction of the detection plate as the sensing plate pair to be tested, and iteratively adjust the initial phase of each excitation signal based on the optimization algorithm so that the initial phases of two adjacent adjustments satisfy the following formula: ； wherein, is the initial phase of the i-th excitation signal during the -th adjustment, is the initial phase of the i-th excitation signal during the -th adjustment, is the phase shift caused by the line delay of the i-th excitation signal and the sensitive probe structure design, is the learning rate, is the induced voltage output by the induced electrode plate to be measured; S4: Use capacitive sensing electronics to measure the induced voltage output by the inductive plate pair to be tested in real time. When the induced voltage output by the inductive plate pair to be tested measured after two consecutive initial phase adjustments satisfies the following formula, the iteration is stopped to complete the phase synchronization monitoring and adjustment of the multi-channel excitation signal: ； Among them, is the induced voltage output by the induction plate under test during the th adjustment, is the induced voltage output by the induction plate under test during the th adjustment, and is the iteration stop parameter.

2. The method for phase synchronization monitoring and adjustment of multi-channel excitation signals according to claim 1, characterized in that: In step S1, the capacitive sensing electronics includes a capacitive sensing circuit and a data processing device connected in sequence, the capacitive sensing circuit is used to transmit an excitation signal to each excitation plate and measure the induced voltage output by the induction plate pair to be tested, and the data processing device is used to run an optimization algorithm; The sensitive probe also includes a fixing device and a vacuum tank, wherein the fixing device, the electrode cage, the six-legged adjustment platform, a plurality of excitation plates, a plurality of induction plates, the electrode cage and the detection plates are all placed in the vacuum tank; The fixing device suspends the detection electrode plate in the electrode cage, a plurality of induction electrodes are uniformly distributed on the electrode cage in an insulated form around the detection electrode plate, and a plurality of excitation electrodes are symmetrically arranged on the electrode cage in an insulated form along the Y-axis direction and the Z-axis direction of the detection electrode plate.

3. The method for phase synchronization monitoring and adjustment of multi-channel excitation signals according to claim 2, characterized in that: The detection electrode plate is a cube, the electrode cage is a cube with a hollow interior, and the capacitive sensing circuit is connected to the sensing electrode plate to be detected and the excitation electrode plate respectively through cables.

4. The phase synchronization monitoring and adjustment method for multi-channel excitation signals according to claim 1, characterized in that: In step S2, different excitation signals have the same frequency but different initial phases.

5. The method for phase synchronization monitoring and adjustment of multi-channel excitation signals according to claim 1, characterized in that: In step S2, the induced voltage output by the electrode plate is detected The expression of which is: ； Among them, is the line delay of the i-th excitation signal and the phase shift caused by the sensitive probe structure design, is the voltage division ratio from the i-th excitation plate to the detection plate, is the amplitude of the i-th excitation signal, is the initial phase of the i-th excitation signal, is the angular frequency of the excitation signal, n = 6.

6. The method for phase synchronization monitoring and adjustment of multi-channel excitation signals according to claim 1, characterized in that: In step S2, the smaller displacement is any value between 10 micrometers and 20 micrometers.

7. The method for phase synchronization monitoring and adjustment of multi-channel excitation signals according to claim 1 or 2, characterized in that: In step S3, the optimization algorithm is a gradient ascent algorithm, Newton's method or a neural network method.

8. The phase synchronization monitoring and adjustment method for multi-channel excitation signals according to claim 1, characterized in that: In step S3: 。 9. The phase synchronization monitoring and adjustment method for multi-channel excitation signals according to claim 2, characterized in that: In step S4, the output voltage of the induction electrode plate pair to be measured : ； Among them, represents the gain of the capacitance sensing circuit, represents the input of the differential capacitance of the induction plate pair, and K is the scale factor. is the amplitude of the i-th excitation signal, is the voltage division ratio from the i-th excitation plate to the detection plate.

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