Wide-range eddy current displacement sensor with three-coil structure and displacement measurement method

Abstract

The invention provides a wide-range eddy current displacement sensor with a three-coil structure and a displacement measurement method, and belongs to the technical field of eddy current displacement sensing. The sensor comprises a three-coil structure eddy current sensor probe, a relay array, a signal processing circuit and an intelligent measurement module which are connected in sequence. The intelligent measurement module outputs an original excitation signal to the signal processing circuit to control the relay array to be switched among different working modes, so that the eddy current sensor probe with the three-coil structure collects an eddy current detection signal in different working modes; and after the detection signal is returned, the intelligent measurement module processes the detection signal and outputs a final displacement measurement result. According to the invention, the influence of unknown metal on the eddy current displacement sensor can be weakened, the output linearity of the sensor is improved, finally, the sensor has the capability of normally working in a complex environment, and the application range of the eddy current sensor is expanded.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of eddy current displacement sensing, and particularly relates to a three-coil structure large-range eddy current displacement sensor and a displacement measurement method, which are used to solve the problem of accurate displacement measurement in a complex metal environment. BACKGROUND

[0002] Eddy current sensors (ECS) are widely used in displacement measurement, vibration monitoring, metal thickness and defect detection, etc. due to their non-contact measurement, wide frequency response range, high resolution, high sensitivity and reliability in harsh environments.

[0003] Traditional eddy current displacement sensors (ECDS) usually adopt a single coil or double coil structure to measure the displacement of the sensor probe to the target metal by detecting the change of coil impedance or induced voltage.

[0004] For an eddy current displacement sensor with a single coil structure, only one coil is responsible for excitation and signal detection. When the metal target approaches, the coil impedance Z changes nonlinearly with the distance d. The impedance change is converted into voltage / current output by the transmitter to realize displacement measurement.

[0005] For an eddy current sensor with a double coil structure, one excitation coil generates a main magnetic field, and the other detection coil receives the eddy current feedback signal. When the displacement changes, the mutual inductance between the two coils and the equivalent circuit of the eddy current changes, which is then reflected in the amplitude of the received coil output signal and the displacement. The detection circuit converts the received signal output into a voltage output that is positively related to the displacement.

[0006] Specifically, the existing eddy current displacement sensors mainly have the following defects: Defect 1, limited range: the range of traditional ECDS is usually less than 1 / 2 of the diameter of its probe. Defect 2, low linearity: in a large-range test scenario, there is a significant nonlinear relationship between the sensor output and the displacement, and the sensitivity and measurement accuracy are insufficient at a larger displacement. Defect 3, susceptible to metal environment interference: the eddy current sensor is highly sensitive to the metal environment, and unknown metal objects other than the detection target will significantly affect the output signal of the sensor, causing system errors.

[0007] Therefore, the current eddy current sensors of any structure have obvious limitations when facing metal environments. The eddy current generated by the metal object will change the electromagnetic field of the sensor, resulting in system measurement errors. To reduce this interference, the traditional method usually maintains the distance between the sensor and the metal object, but this method is often not feasible for large-scale measurement.

[0008] In recent years, some improvement schemes have been proposed, mostly relying on complex hardware design, and poor adaptability to metal environment in practical application, which is difficult to meet the high-precision measurement demand in complex environment in industrial scene. Among them, for the above-mentioned defect 1, the three-coil differential feedback compensation method can expand the range of the eddy current sensor to more than 3 times the coil diameter. SUMMARY

[0009] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a three-coil structure large-range eddy current displacement sensor and a displacement measurement method. The present application can weaken the influence of unknown metal on the eddy current displacement sensor and improve the linearity of the sensor output, ultimately enabling the sensor to work normally in complex environment and expanding the application range of the eddy current sensor.

[0010] The present application provides a three-coil structure large-range eddy current displacement sensor, which comprises a three-coil structure eddy current sensor probe, a relay array, a signal processing circuit and an intelligent measurement module connected in sequence. The intelligent measurement module controls the relay array to switch between different working modes by outputting the original excitation signal to the signal processing circuit, so that the three-coil structure eddy current sensor probe collects eddy current detection signals in different working modes. The eddy current detection signals collected in different working modes are sent to the signal processing circuit through the relay array for conditioning, and finally returned to the intelligent measurement module. The intelligent measurement module processes the eddy current detection signals and outputs the final displacement measurement result.

[0011] In one specific embodiment of the present application, the three-coil structure eddy current sensor probe comprises a central main coil and two secondary coils symmetrically arranged opposite to the main coil, and the three coils have consistent parameters, each coil being connected to the relay array. The three-coil structure eddy current sensor probe is used to generate an alternating magnetic field in different working modes, induce an eddy current in the measured target, and then receive the detection signal of the eddy current from the coil and output it to the relay array.

[0012] In one specific embodiment of the present application, the relay array is connected to the excitation end and the receiving end of the signal processing circuit respectively. The relay array is used to change the connection mode between the excitation end and the receiving end of the signal processing circuit and the three coils in the three-coil structure eddy current sensor probe according to the received excitation signal, and output the excitation signal to the three-coil structure eddy current sensor probe, so as to generate different working modes.

[0013] In each working mode, the relay array selects two coils from the three coils of the three-coil structure eddy current sensor probe; one of the two coils is used as an excitation source to generate an excitation magnetic field, and the other coil is used as a detector to detect an eddy current signal; and six working modes are generated.

[0014] In one specific embodiment of the present application, the signal processing circuit is configured to receive the original excitation signal generated by the intelligent measurement module, amplify the power of the original excitation signal, and then output the power-amplified excitation signal to the relay array; the signal processing circuit is also configured to receive the eddy current detection signals in different working modes output by the relay array, filter and amplify the detection signals, and then output the filter-amplified detection signals to the intelligent measurement module.

[0015] In one specific embodiment of the present application, the intelligent measurement module receives the amplitudes of the detection signals in the six working modes, which is equivalent to obtaining the measurement results of six different position double-coil eddy current sensors, and the intelligent measurement module calculates the amplitudes of the detection signals in the six working modes using a preset intelligent compensation algorithm to obtain an estimated value of displacement.

[0016] In one specific embodiment of the present application, the signal processing circuit includes a power amplification circuit sub-module, an instrument amplification circuit sub-module, and a filter circuit sub-module; the power amplification circuit sub-module receives the original excitation signal output by the intelligent measurement module and amplifies the original excitation signal, and then outputs the power-amplified excitation signal to the relay array through the excitation end; the instrument amplification circuit sub-module receives the detection signals from the relay array through the receiving end and outputs the detection signals to the filter circuit sub-module; and the filter circuit sub-module filters the received detection signals and then outputs the filter-amplified detection signals to the intelligent measurement module.

[0017] The present application also provides a displacement measurement method of the above-mentioned three-coil structure large-range eddy current displacement sensor, which comprises:

[0018] 1) calibration stage;

[0019] 1-1) selecting a plurality of displacement values at equal intervals within the range of the sensor;

[0020] 1-2) based on the results of step 1-1), setting the displacement values x in the calibration process on a standard displacement table;

[0021] 1-3) the intelligent measurement module generates an original excitation signal, controls the relay array to switch six working modes in sequence through the signal control circuit, and then acquires the eddy current detection signals in the six working modes collected by the three-coil structure eddy current sensor probe;

[0022] 1-4) The amplitudes of the eddy current detection signals in the six working modes obtained in step 1-3) are taken as calibration measurement values to form a calibration measurement matrix Y0;

[0023] An intermediate value is obtained by matrix inversion of Y0

[0024] 1-5) The displacement value x is subjected to exponential transformation to obtain a mutual inductance approximation value M x = e x ;

[0025] 1-6) Steps 1-2) to 1-5) are repeated to obtain Z0 and M x combination for each displacement value x;

[0026] 1-7) Based on the results of step 1-6), a linear discriminant analysis (LDA) algorithm is run with Z0 as input and M x as output to fit a linear transformation matrix A;

[0027] Then, each Z0 is reduced to an intermediate variable L0 with a dimension of 3;

[0028] 1-8) A support vector regression (SVR) algorithm is run with L0 as input and M x as output to fit a linear transformation matrix B;

[0029] 2) Measurement phase;

[0030] 2-1) When measuring the target, the intelligent measurement module generates a raw excitation signal, and the signal control circuit controls the relay array to switch six working modes in turn, and then obtains the eddy current detection signals collected by the three-coil structure eddy current sensor probe in the six working modes;

[0031] 2-2) The amplitudes of the eddy current detection signals in the six working modes obtained in step 2-1) are taken as actual measurement values to form an actual measurement matrix Y1;

[0032] An intermediate value is obtained by matrix inversion of Y1

[0033] 2-3) Z1 is multiplied by the linear transformation matrix A to reduce Z1 to a three-dimensional vector L1:

[0034] L1 = AZ1

[0035] 2-4) L1 is multiplied by the linear transformation matrix B to obtain a mutual inductance estimate value

[0036]

[0037] 2-5) The actual measurement matrix Y1 is multiplied by the linear transformation matrix A to obtain a three-dimensional vector L1: Performing inverse exponential transformation to obtain the estimated value of displacement That is, the measurement result is:

[0038]

[0039] 2-6) The intelligent measurement module outputs the measurement result to the outside through the serial port, and the measurement is completed.

[0040] In one specific embodiment of the present application, it further comprises:

[0041] The calibration measurement matrix Where m 0i Is the calibration measurement value obtained under the working mode i, i = 1, 2, …, 6;

[0042] The actual measurement matrix Where m i Is the actual measurement value obtained under the working mode i, i = 1, 2, …, 6.

[0043] The characteristics and benefits of the present application are:

[0044] 1) The present application proposes a three-coil large-range eddy current displacement sensor, which adds a relay array to the three-coil structure eddy current displacement sensor, controls the circuit connection between the signal processing circuit and the three-coil structure eddy current sensor probe, obtains the measurement result under six different working modes, and outputs it to the intelligent measurement module. The intelligent measurement module executes an intelligent compensation algorithm, which can weaken the influence of unknown metals around the sensor on the sensor, so that the sensor can realize accurate measurement of displacement and improve the linearity of the sensor in large-range measurement.

[0045] 2) The present application can realize fast switching between different working modes of the sensor through the relay array.

[0046] 3) The present application obtains intelligent compensation algorithm parameters based on nonlinear transformation (exponential transformation, matrix inverse, etc.) and linear regression method (LDA, SVR, etc.), compensates the sensor output using the measurement results under six different working modes, eliminates the system error caused by unknown metals on displacement measurement, and enables the sensor to accurately measure displacement at a long distance.

[0047] 4) The present application can dynamically adapt to different metal environments, improve the adaptability and reliability of the sensor in complex environments. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 It is a structure diagram of a three-coil structure large-range eddy current displacement sensor of an embodiment of the present application.

[0049] Figure 2The control logic and circuit structure of the relay array of one specific embodiment of the present application.

[0050] Figure 3 The comparison chart of the sensor output results before and after running the intelligent compensation algorithm in one specific embodiment of the present application. DETAILED DESCRIPTION

[0051] The present application provides a three-coil structure large-range eddy current displacement sensor and a displacement measurement method, which will be described in detail below in combination with the drawings and specific embodiments.

[0052] The present application provides a three-coil structure large-range eddy current displacement sensor, which has a structure as shown in the figure. Figure 1 The three-coil structure eddy current sensor probe is connected with the relay array, the other end of the relay array is connected with the signal processing circuit, and the other end of the signal processing circuit is connected with the intelligent measurement module. In the present embodiment, the intelligent measurement module outputs the original excitation signal to the signal processing circuit to control the relay array to switch between different working modes, so that the three-coil structure eddy current sensor probe collects eddy current detection signals in different working modes; the eddy current detection signals collected in the different modes are sent to the signal processing circuit through the relay array for conditioning, and finally returned to the intelligent measurement module, which processes the eddy current detection signals using a preset intelligent compensation algorithm and outputs the final displacement measurement result.

[0053] Specifically:

[0054] The three-coil structure eddy current sensor probe includes a central main coil and two secondary coils symmetrically arranged opposite to the main coil, and the three coils have consistent parameters, and each coil is connected with the relay array. The three-coil structure eddy current sensor probe is used to generate an alternating magnetic field in different modes, induce an eddy current in the measured target, and then receive the detection signal of the eddy current from the coil and output it to the relay array. The present embodiment has no special requirements for the coil, and in one specific embodiment of the present application, the coil skeleton is made of nylon material, the coil is wound with copper enameled wire, the diameter is about 20 mm, the number of turns is about 120, the parameters of the main coil and the two secondary coils are consistent, and the distance is 20 mm.

[0055] The relay array is configured to change the connection mode between the excitation end and the receiving end of the signal processing circuit and the three coils of the three-coil structure eddy current sensor probe according to the received excitation signal, output the excitation signal to the three-coil structure eddy current sensor probe, and output the eddy current detection signals of the three-coil structure eddy current sensor probe in different working modes to the signal processing circuit.

[0056] In each working mode, the relay array selects two coils from the three coils of the three-coil structure eddy current sensor probe; one of the two coils is used as an excitation source to generate an excitation magnetic field, and the other coil is used as a detector to detect an eddy current signal; and the embodiment generates six working modes.

[0057] The intelligent measurement module is configured to embed an intelligent compensation algorithm in a field programmable gate array (FPGA) to generate a raw excitation signal and output the raw excitation signal to the signal processing circuit, the excitation signal being used to control the working state of the relays in the relay array, thereby changing the connection mode between the excitation end and the receiving end of the signal processing circuit and the three coils of the three-coil structure eddy current sensor probe to generate different working modes, and further enabling the three-coil structure eddy current sensor probe to collect eddy current detection signals in different working modes. The intelligent measurement module is also configured to run the embedded intelligent compensation algorithm according to the eddy current detection signals in different modes received from the signal processing circuit, calculate a displacement measurement result, and output the displacement measurement result to the outside through a serial port. In the embodiment, the intelligent measurement module outputs six different working mode electric signals to control the relay array. The intelligent measurement module has the computing capability required for running the intelligent compensation algorithm, and can use, but is not limited to, an MCU and an FPGA, and can perform analog / digital conversion to generate a raw excitation signal and digitize a detection signal. In a specific embodiment of the present application, the FPGA is used to implement the embedded implementation of the intelligent compensation algorithm.

[0058] The signal processing circuit is configured to receive a raw excitation signal generated by the intelligent measurement module, amplify the power of the raw excitation signal, and then output the power-amplified excitation signal to the relay array; the signal processing circuit is also configured to receive an eddy current detection signal in different working modes output by the relay array, filter and amplify the detection signal, and then output the filter-amplified detection signal to the intelligent measurement module. The signal processing circuit comprises a power amplification circuit sub-module, an instrument amplification circuit sub-module, and a filter circuit sub-module. The power amplification circuit sub-module receives the raw excitation signal output by the intelligent measurement module, amplifies the raw excitation signal, and then outputs the amplified excitation signal to the relay array through an excitation end; the instrument amplification circuit sub-module receives the detection signal from the relay array through a receiving end and outputs the detection signal to the filter circuit sub-module; and the filter circuit sub-module filters the received detection signal and then outputs the filtered detection signal to the intelligent measurement module. In this embodiment, the signal processing circuit is built using an OPA2227.

[0059] Further, in this embodiment, the basic principle of the intelligent compensation algorithm is that, by adjusting the relay array, the measurement results (i.e. the amplitudes of the detection signals) in six working modes are obtained, which are equivalent to the measurement results of a double-coil eddy current sensor in six different positions, and then the measurement results in the six working modes are solved into displacement values.

[0060] In this embodiment, the relay array comprises four relays, and the logic of controlling the on-off of the relays according to the electrical signals is as shown in Figure 2 Figure 2 In the logic, X represents that the input end of the relay is connected to the X output end and disconnected from the Y output end (denoted as being in the X state); Y represents that the input end of the relay is connected to the Y output end and disconnected from the X output end (denoted as being in the Y state); and O represents that the relay can be in either the X or Y state, without affecting the working effect of the relay array. As shown in the upper half of Figure 2 , in mode 1, the relays L1 and L2 are in the X state, and the relays L3 and L4 have no requirement on the state; in mode 2, the relays L1 and L4 are in the X state, the relay L2 is in the Y state, and the relay L3 has no requirement on the state; in mode 3, the relay L3 is in the X state, and the relays L1, L2, and L4 are in the Y state; in mode 4, the relays L1, L2, L3, and L4 are all in the Y state; in mode 5, the relays L3 and L4 are in the X state, and the relays L1 and L2 are in the Y state; and in mode 6, the relay L2 is in the X state, the relays L1 and L3 are in the Y state, and the relay L4 has no requirement on the state. The structure of the relay array in this embodiment is as shown in the lower half of Figure 2 . This embodiment has no special requirements on the number and specific connection mode of the relays, and mainly guarantees the connection mode between the excitation end, the receiving end of the signal processing circuit, and the three coils in the six states. The six working modes are as follows: ​

[0061] Mode 1: Primary coil as excitation source, secondary coil 1 as detector.

[0062] Mode 2: Primary coil as excitation source, secondary coil 2 as detector.

[0063] Mode 3: Secondary coil 1 as excitation source, primary coil as detector.

[0064] Mode 4: Secondary coil 2 as excitation source, primary coil as detector.

[0065] Mode 5: Secondary coil 1 as excitation source, secondary coil 2 as detector.

[0066] Mode 6: Secondary coil 2 as excitation source, secondary coil 1 as detector.

[0067] It should be noted that in a single measurement, the six modes are switched in turn by the relay array, and the corresponding measurement data are read by the intelligent measurement module and the displacement is calculated.

[0068] Further, the embodiment also proposes a displacement measurement method of the large-range eddy current displacement sensor based on the above three-coil structure, including a calibration stage and a measurement stage. In the calibration stage, the sensor is tested on a standard displacement table, and the measurement results under six different working modes at different displacements are collected, which are used to run the LDA algorithm and the SVR algorithm to fit the linear transformation matrix; in the measurement stage, based on the intelligent compensation algorithm, the linear transformation matrix fitted, the matrix inverse operation and the exponential transformation are used to calculate the displacement value from the measurement results obtained from the six different measurement modes. The specific steps of the method are as follows:

[0069] 1) Calibration stage.

[0070] This stage needs to be performed once on a standard displacement table after determining the measurement target to determine the related parameters of the intelligent compensation algorithm, and does not need to be repeated during use.

[0071] 1-1) Select several different displacement values at equal intervals in the required sensor range (the embodiment suggests that the number of displacement values is greater than 10).

[0072] 1-2) Based on the results of step 1), set the displacement value x in the calibration process on the standard displacement table, x being any displacement value selected in step 1-1).

[0073] 1-3) The intelligent measurement module generates a stable original excitation signal, controls the relay array to switch the six working modes in turn through the signal control circuit, and then acquires the eddy current detection signals under the six working modes collected by the three-coil structure eddy current sensor.

[0074] 1-4) The amplitudes of the eddy current detection signals in the six working modes obtained in step 1-3) are taken as calibration measurement values to form a calibration measurement matrix Y0, in the embodiment wherein m 0i is the calibration measurement value obtained in working mode i, i = 1, 2, …, 6.

[0075] The intermediate value is obtained by matrix inversion of Y0

[0076] 1-5) The displacement value x is subjected to exponential transformation to obtain the mutual inductance approximation value M x = e x ;

[0077] 1-6) Steps 1-2) to 1-5) are repeated to obtain Z0 and M x combination for each displacement value x.

[0078] 1-7) Based on the results of step 1-6), the LDA (Linear Discriminant Analysis) algorithm is run with Z0 as input and M x as output, and a linear transformation matrix A is fitted.

[0079] Then, each Z0 is reduced in dimension to an intermediate variable L0 of dimension 3.

[0080] 1-8) The SVR (Support Vector Regression) algorithm is run with L0 as input and M x as output, and a linear transformation matrix B is fitted.

[0081] The linear transformation matrices A, B are recorded for use in the subsequent measurement phase.

[0082] 2) Measurement phase.

[0083] 2-1) When measuring the target, the intelligent measurement module generates a stable original excitation signal, and the signal control circuit controls the relay array to switch the six working modes in turn, and then the eddy current detection signals in the six working modes collected by the three-coil structure eddy current sensor probe are obtained.

[0084] 2-2) The amplitudes of the eddy current detection signals in the six working modes obtained in step 2-1) are taken as actual measurement values to form an actual measurement matrix Y1, in the embodiment wherein m i is the actual measurement value obtained in working mode i, i = 1, 2, …, 6.

[0085] The intermediate value is obtained by matrix inversion of Y1

[0086] 2-3) multiply Z1 with the linear transformation matrix A obtained in the calibration stage, thereby reducing Z1 to a three-dimensional vector L1:

[0087] L1 = AZ1

[0088] 2-4) multiply L1 with the linear transformation matrix B obtained in the calibration stage to obtain the mutual inductance estimation value

[0089]

[0090] 2-5) perform inverse exponential transformation on to obtain the estimation value of displacement , which is the measurement result:

[0091]

[0092] 2-6) the intelligent measurement module outputs the measurement result to the outside through a serial port, and the measurement is completed.

[0093] In one specific embodiment of the present application, the output results of the sensor before and after running the intelligent compensation algorithm are compared as shown in Figure 3 . Among them, the horizontal coordinate is the displacement generated by the standard displacement table, the vertical coordinate is the displacement measurement value (unit: mm) output by the sensor, the output before compensation is marked with a cross, the output after compensation is marked with a dot, and the two straight lines are the linear fitting results corresponding to the output before compensation and the output after compensation. The results show that the three-coil structure large-range eddy current displacement sensor described in the present embodiment effectively eliminates the system error caused by unknown metal, and the linear fitting results between the sensor output and the displacement before and after compensation are y = 2.88x - 27.68, R 2 = 0.9332, y = 1.02 + 0.03, R 2 = 0.9945, thereby indicating that the intelligent compensation algorithm of the present embodiment significantly improves the linearity of the output.

Claims

1. A three-coil structure large-range eddy current displacement sensor, characterized in that: The invention comprises a three-coil structure eddy current sensor probe, a relay array, a signal processing circuit, and an intelligent measurement module connected in sequence; wherein the intelligent measurement module controls the relay array to switch between different working modes by outputting an original excitation signal to the signal processing circuit, so that the three-coil structure eddy current sensor probe collects eddy current detection signals in different working modes; the eddy current detection signals collected in different working modes are sent to the signal processing circuit through the relay array for conditioning, and finally returned to the intelligent measurement module, and the intelligent measurement module processes the eddy current detection signals and outputs the final displacement measurement results.

2. The sensor according to claim 1, characterized in that The three-coil structure eddy current sensor probe includes: a main coil located in the center and two secondary coils arranged symmetrically relative to the main coil. The three coils have consistent parameters, and each coil is connected to the relay array respectively. The three-coil structure eddy current sensor probe is used to generate an alternating magnetic field in different working modes, induce eddy currents in the target being measured, and then receive the coil's detection signal of the eddy current and output it to the relay array.

3. The sensor according to claim 2, characterized in that The relay array is respectively connected to the excitation end and the receiving end of the signal processing circuit; the relay array is used to change the connection mode between the excitation end and the receiving end of the signal processing circuit and the three coils in the three-coil structure eddy current sensor probe according to the received excitation signal, and output the excitation signal to the three-coil structure eddy current sensor probe, thereby generating different working modes; Among them, in each working mode, the relay array selects two coils from the three coils of the three-coil structure eddy current sensor probe; among the two coils, one coil is used as an excitation source to generate an excitation magnetic field, and the other coil is used as a detector to detect eddy current signals; a total of six working modes are generated.

4. The sensor according to claim 3, characterized in that The signal processing circuit is used to receive the original excitation signal generated by the intelligent measurement module and perform power amplification, and then output the power-amplified excitation signal to the relay array; the signal processing circuit is also used to receive the eddy current detection signal under different working modes output by the relay array and perform filtering and amplification, and then output the filtered and amplified detection signal to the intelligent measurement module.

5. The sensor according to claim 4, characterized in that The intelligent measurement module receives the amplitudes of the detection signals under the six working modes, which is equivalent to obtaining the measurement results of the dual-coil eddy current sensors in six different positions. The intelligent measurement module uses a preset intelligent compensation algorithm to calculate the amplitudes of the detection signals under the six working modes to obtain an estimated value of the displacement.

6. The sensor according to claim 4, characterized in that The signal processing circuit includes: a power amplifier circuit submodule, an instrument amplifier circuit submodule and a filter circuit submodule; the power amplifier circuit submodule receives and amplifies the original excitation signal output by the intelligent measurement module, and then outputs it to the relay array through the excitation terminal; the instrument amplifier circuit submodule receives a detection signal from the relay array through the receiving terminal and outputs it to the filter circuit submodule; the filter circuit submodule filters the received detection signal and then outputs it to the intelligent measurement module.

7. A displacement measurement method based on the sensor according to any one of claims 3 to 6, characterized in that: include: 1) Calibration stage; 1-1) Select several displacement values ​​equidistantly within the sensor range; 1-2) Based on the result of step 1-1), a displacement value x during the calibration process is set on the standard translation stage; 1-3) The intelligent measurement module generates the original excitation signal, controls the relay array to switch between six operating modes in sequence through the signal control circuit, and then obtains the eddy current detection signals under the six operating modes collected by the three-coil structure eddy current sensor probe; 1-4) using the amplitudes of the eddy current detection signals under the six working modes obtained in step 1-3) as calibration measurement values ​​to form a calibration measurement matrix Y0; Find the intermediate value by inverting the matrix of Y0 1-5) Perform exponential transformation on the displacement value x to obtain the mutual inductance approximation M x =e x ; 1-6) Repeat steps 1-2) to 1-5) to obtain Z0 and M at each displacement value x x combination; 1-7) Based on the result of step 1-6), take Z0 as input, M x As output, run the linear discriminant analysis LDA algorithm and fit the linear transformation matrix A; Then, each Z0 is reduced to an intermediate variable L0 with a dimension of 3; 1-8) Take L0 as input, M x As output, run the support vector regression SVR algorithm to fit the linear transformation matrix B; 2) Measurement phase; 2-1) When measuring the target, the intelligent measurement module generates an original excitation signal, controls the relay array through the signal control circuit to switch between six operating modes in sequence, and then obtains the eddy current detection signals collected by the three-coil eddy current sensor probe in each of the six operating modes; 2-2) The amplitudes of the eddy current detection signals under the six working modes obtained in step 2-1) are used as actual measurement values ​​to form an actual measurement matrix Y1; Find the intermediate value by inverting the matrix of Y1 2-3) Multiply Z1 by the linear transformation matrix A to reduce the dimension of Z1 to a three-dimensional vector L1: L1=AZ1 2-4) Multiply L1 by the linear transformation matrix B to obtain the mutual inductance estimate 2-5) Yes Perform an inverse exponential transform to get an estimate of the displacement The measurement result is: 2-6) The intelligent measurement module outputs the measurement results through the serial port, and the measurement is completed.

8. The method according to claim 7, characterized in that Also includes: The calibration measurement matrix where m 0i is the calibration measurement value obtained in working mode i, i = 1, 2, ..., 6; The actual measurement matrix where m i is the actual measurement value obtained in working mode i, i = 1, 2, ..., 6.

Images