CN116087284A - Method and system for acquiring sensing depth of coplanar capacitive sensor - Google Patents
Method and system for acquiring sensing depth of coplanar capacitive sensor Download PDFInfo
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Abstract
The invention relates to a method and a system for acquiring sensing depth of a coplanar capacitive sensor, belongs to the field of nondestructive detection, and solves the problem that the acquired sensing depth cannot effectively reflect the effective detection distance of the coplanar capacitive sensor due to incomplete consideration or inconsistent result in the acquisition method in the prior art. The method of the invention comprises the following steps: determining the sensing depth of the target sensor according to the change of the sensitivity data of the measuring domain of the target sensor in the depth direction; wherein the depth direction is a direction away from and perpendicular to a surface of the target sensor. The sensing depth obtained by the method is consistent in result, and the effect of effectively measuring the effective detection distance of the target sensor and accurately reflecting the performance of the target sensor is realized.
Description
Technical Field
The invention relates to the technical field of nondestructive testing, in particular to a method and a system for acquiring sensing depth of a coplanar capacitive sensor.
Background
The coplanar capacitive detection technique is a novel non-destructive testing (NDT) technique developed from capacitive tomography (electrical capacitance tomography, ECT). The coplanar capacitive sensor provides more flexible electrode design and single-sided detection capability on the basis of inheriting the advantages of low ECT cost, quick response, no radiation, non-invasiveness and the like. The same-surface capacitance detection technology has shown wide research value and application potential in nondestructive detection fields such as composite material damage, moisture content, surface defects, concrete flaw detection and the like.
The sensing depth (also called penetration depth) is an important index for measuring the effective detection distance of the co-planar capacitive sensor, and is one of the key factors influencing the performance of the co-planar capacitive sensor. However, due to the complexity of fringe fields and the diversity of parameter designs, the sensing depth of the current coplanar capacitive sensor does not have a uniform acquisition standard.
The current sensing depth acquisition method comprises three steps: (1) Defining a position where the electric field intensity attenuation of the center of the sensor is close to zero as a sensing depth; (2) Placing a test sample which is gradually thickened on the sensor, and defining the height corresponding to 97% of the capacitance change quantity caused by the test sample approaching the maximum value as the sensing depth; (3) A thin plate test sample of a fixed thickness was placed on the sensor, and the height at which the amount of change caused by the stepwise elevation of the sample was approximately 3% of the maximum value was defined as the sensing depth. The above three methods have certain drawbacks, specifically, the method (1) only focuses on the central electric field intensity of the sensor, and does not consider other positions of the measuring field of the sensor, so that the investigation is not comprehensive enough, and meanwhile, since the electric field intensity is vector and has directivity, the direction of the electric field intensity at each position of the measuring field is not consistent, the sensing depth cannot be obtained comprehensively according to the electric field intensity, and thus the effective detection distance of the sensor cannot be effectively measured. The method (2) and the method (3) are used for obtaining the sensing depth through experiments by testing samples, wherein the method (2) has larger difficulty in sample preparation and experimental operation, the method (3) is easy to realize by means of a displacement platform, but the sensing depth obtained by the method (2) and the method (3) is inconsistent and lacks uniformity due to the difference between the test samples (size, materials and the like) and experimental conditions (displacement precision, capacitance measurement precision and the like), so that the effective detection distance of the sensor cannot be effectively measured by determining the sensing depth according to the experimental method.
Therefore, a method for acquiring the sensing depth of the in-plane array sensor, which can overcome the defects, is important to research and development of in-plane capacitance detection technology.
Disclosure of Invention
In view of the above analysis, the embodiment of the invention aims to provide a method and a system for acquiring sensing depth of a coplanar capacitive sensor, which are used for solving the technical problem that the acquired sensing depth cannot effectively measure the effective detection distance of the coplanar capacitive sensor due to incomplete consideration or inconsistent result in the existing method.
In one aspect, an embodiment of the present invention provides a method for acquiring a sensing depth of a coplanar capacitive sensor, where the method includes:
acquiring the sensing depth of the target sensor according to the change of the sensitivity data of the measuring domain of the target sensor in the depth direction;
wherein the depth direction is a direction away from and perpendicular to a surface of the target sensor.
Based on a further improvement of the above method, the sensitivity data comprises: the surface layers of different depths of the measurement domain respectively correspond to the average sensitivity,
wherein the average sensitivity of the facing for each depth is the average of the sensitivities of all locations in the designated area of the facing.
Based on a further improvement of the above method, the designated area is a part or all of the area on the facing layer.
Based on a further improvement of the above method, the method comprises the steps of:
acquiring a sensitivity matrix of a measurement domain of the target sensor in a three-dimensional space;
calculating average sensitivities respectively corresponding to the surface layers with different depths of the measuring domain according to the sensitivity matrix;
obtaining the maximum value in the calculated average sensitivity corresponding to the surface layer of each depth of the measurement domain;
searching a target surface layer, wherein the ratio of the average sensitivity corresponding to the target surface layer to the maximum value is a preset ratio;
the distance between the target surface layer and the surface of the target sensor is calculated as the sensing depth of the target sensor.
Based on a further improvement of the above method, the preset ratio is 2% to 5%.
Based on the further improvement of the method, the measurement domain of the target sensor is subjected to finite element meshing on a three-dimensional space, and a sensitivity matrix of the measurement domain of the target sensor in the three-dimensional space is obtained based on a finite element analysis method.
Based on a further improvement of the above method, the sensitivity matrix is calculated according to the following formula:
wherein S is a sensitivity matrix;
a potential distribution of the measurement domain when the first electrode is energized and the second electrode is grounded; />
A potential distribution of the measurement domain when the second electrode is energized and the first electrode is grounded; v (V) 1 A voltage at which the first electrode is energized; v (V) 2 A voltage at which the second electrode is energized; I. j and K are the total number of divisions of the measurement domain in the X direction, the Y direction and the Z direction, and i, J and K are the coordinates of the solution unit in the X direction, the Y direction and the Z direction;
wherein the first electrode and the second electrode are two electrodes in any electrode pair of the target sensor respectively; the Z direction is the depth direction, the X direction, the Y direction are two directions perpendicular to the Z direction, and X, Y and Z satisfy the right hand rule.
Based on a further improvement of the above method, the average sensitivity of the layers of the measurement domain is calculated according to the following formula:
wherein M is k S (I, j, k) is the sensitivity corresponding to the solving unit with coordinates (I, j, k) and is the average sensitivity corresponding to the kth layer, I 0 And I 1 Respectively the starting point coordinate and the end point coordinate of the appointed region of the kth layer in the X direction, J 0 And J 1 The start point coordinates and the end point coordinates of the designated region of the k-th layer in the Y direction, respectively.
Based on a further improvement of the method, the finite element meshing of the measurement domain of the target sensor in three-dimensional space comprises:
and carrying out hexahedral mesh division on the measurement domain of the target sensor in a three-dimensional space.
In another aspect, embodiments of the present invention provide an acquisition system of a sensing depth of a coplanar capacitive sensor, the acquisition system including:
the first solving module is used for acquiring a sensitivity matrix of a measurement domain of the target sensor in a three-dimensional space;
a first calculation module for calculating the average sensitivity corresponding to each height layer of the measurement domain according to the sensitivity matrix;
the searching module is used for obtaining the maximum value in the calculated average sensitivities corresponding to all the height layers and searching a target surface layer, wherein the ratio of the average sensitivities corresponding to the target surface layer to the maximum value is a preset ratio;
a second calculation module for calculating a distance between the target surface layer and a surface of the target sensor as a sensing depth of the target sensor.
Compared with the prior art, the invention has at least one of the following beneficial effects:
1. according to the method, the sensing depth is acquired according to the change of the sensitivity data of the measuring domain of the target sensor in the depth direction, and the sensitivity data is unique and is independent of the test sample and experimental conditions, so that the problem that the acquired sensing depth results are inconsistent due to the difference of the test sample and/or the experimental conditions can be solved, and the consistency of the acquired results is ensured.
2. According to the invention, the sensing depth of the target sensor is determined through the change of the average sensitivity corresponding to the surface layer of each depth of the measuring domain in the depth direction, and the acquired sensing depth can fully consider different positions of the measuring domain, so that the problem that the acquired sensing depth cannot effectively measure the effective detection distance of the sensor due to incomplete consideration is avoided, and the performance of the sensor can be accurately reflected.
In the invention, the technical schemes can be mutually combined to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, like reference numerals being used to refer to like parts throughout the several views.
Fig. 1 is a flowchart of a method for acquiring a sensing depth of a co-planar capacitive sensor according to an embodiment of the present invention.
FIG. 2 is a schematic diagram of a coplanar capacitive sensor and measurement fields thereof according to an embodiment of the present invention;
FIG. 3 is a finite element meshing schematic of the measurement domain of a coplanar capacitive sensor according to an embodiment of the present invention;
fig. 4 is a graph showing a variation trend of average sensitivity in a depth direction corresponding to each surface layer according to an embodiment of the present invention.
Reference numerals:
1-a measurement domain; 2-a first electrode; 3-a second electrode; 4-substrate.
Detailed Description
Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and together with the description serve to explain the principles of the invention, and are not intended to limit the scope of the invention.
The invention discloses a method for acquiring sensing depth of a coplanar capacitive sensor. The acquisition method comprises the following steps: the sensing depth of the target sensor is acquired according to the change of the sensitivity data of the measuring field 1 of the target sensor in the depth direction.
Wherein the depth direction is a direction away from and perpendicular to a surface of the target sensor.
Specifically, the sensitivity data of the measurement domain 1 of the target sensor directly reflects the ability of the target sensor to measure the smallest measured at different locations of the measurement domain 1. In general, the sensitivity distribution of the measuring field 1 is variable, the sensitivity is different at different locations, wherein the sensitivity is smaller at locations farther from the surface of the sensor than at locations nearer to the surface of the sensor, in other words, the sensitivity of the measuring field 1 of the sensor is gradually decaying in its depth direction, i.e. the ability to measure the smallest measured is gradually decreasing in the depth direction. Therefore, the sensing depth of the target sensor can be determined from the change in the depth direction of the sensitivity data thereof.
Compared with the prior art, in the method provided by the embodiment of the invention, the sensing depth is determined according to the change of the sensitivity data of the measuring field 1 of the target sensor in the depth direction, and the sensitivity data is unique and independent of the test sample and experimental conditions, so that the problem that the obtained sensing depth results are inconsistent due to the difference of the test sample and/or the experimental conditions can be solved, and the consistency of the obtained results is ensured.
The target sensor is a coplanar capacitive sensor whose sensing depth is to be obtained. The coplanar capacitive sensor comprises a shell and a plurality of electrodes, wherein the electrodes are arranged in the shell, and the surface of the target sensor is the surface of the shell of the target sensor. In addition, all electrodes of the coplanar capacitive sensor are arranged on the same plane, so that single-sided detection is realized.
In a preferred embodiment of the present invention, the sensitivity data includes: the surface layers with different depths of the measuring domain 1 respectively correspond to average sensitivities, wherein the average sensitivity corresponding to the surface layer with each depth is the average value of the sensitivities of all positions in a designated area of the surface layer.
In this embodiment, the sensing depth of the target sensor is determined by measuring the change of the average sensitivity corresponding to the surface layer of each depth of the domain 1 in the depth direction, and the acquired sensing depth can fully consider different positions of the domain 1, so that the problem that the acquired sensing depth cannot effectively measure the effective detection distance of the sensor due to incomplete consideration is avoided, and thus the performance of the sensor can be accurately reflected.
Specifically, the designated area is a part or all of the area on the surface layer. In practice, the sensitivity of the surface layer may be calculated from the sensitivity of each position in the entire region of the surface layer, or the average sensitivity of the surface layer may be calculated from the sensitivity of each position in a partial region, preferably the central region, of the surface layer.
For example, if the sensitivity of the edge region of the surface layer is greatly different from the sensitivity of the center region thereof, the average sensitivity of the surface layer can be calculated only by the sensitivity of each position of the center region of the surface layer of each depth, so as to improve the accuracy of the calculation result.
Generally, when calculating the average sensitivity corresponding to each of the surface layers of each depth, the size and position of the selected designated area on the surface layer of each depth should be consistent.
As shown in fig. 1, in a specific embodiment of the present invention, the method includes the steps of:
step 1: and acquiring a sensitivity matrix of the measuring domain 1 of the target sensor in a three-dimensional space.
Step 2: and calculating the average sensitivities respectively corresponding to the surface layers with different depths of the measuring domain 1 according to the sensitivity matrix.
Step 3: and acquiring the maximum value in the calculated average sensitivity corresponding to the surface layer of each depth of the measurement domain 1.
Step 4: and searching the target surface layer. The ratio of the average sensitivity corresponding to the target surface layer to the maximum value is a preset ratio.
Step 5: the distance between the target surface layer and the surface of the target sensor is calculated as the sensing depth of the target sensor.
In this embodiment, in step 1, the sensitivity distribution of the measurement domain 1 of the target sensor in the three-dimensional space is represented by a sensitivity matrix. In step 2, calculating the average sensitivity corresponding to each surface layer with different depths according to the sensitivity matrix. Steps 3 to 5 are steps of determining the sensing depth of the target sensor according to the change (attenuation trend) of the average sensitivity corresponding to each surface layer in the depth direction.
The average sensitivity of the surface layers closer to the surface of the target sensor is larger, and in general, the maximum value of the average sensitivities of the respective surface layers may occur in the first to third layers in the depth direction, for example, the average sensitivity of the first layer is the largest.
Specifically, in step 4, the preset ratio may take a value in a range of 1% to 5%. Preferably, the preset ratio is 3%.
One embodiment of the invention discloses that the measuring domain 1 of the target sensor is subjected to finite element meshing on a three-dimensional space, and a sensitivity matrix of the measuring domain 1 of the target sensor on the three-dimensional space is obtained based on a finite element analysis method.
Wherein the sensitivity matrix is calculated according to the following formula:
wherein S is a sensitivity matrix;
a potential distribution of the measurement domain 1 when the first electrode 2 is excited and the second electrode 3 is grounded; />
A potential distribution of the measurement domain 1 when the second electrode 3 is excited and the first electrode 2 is grounded; v (V) 1 A voltage at which the first electrode 2 is energized; v (V) 2 A voltage at which the second electrode 3 is energized; I. j and K are the total number of divisions of the measurement domain 1 in the X direction, the Y direction, and the Z direction, respectively, and i, J, and K are the coordinates of the solution unit in the X direction, the Y direction, and the Z direction, respectively;
wherein the first electrode 2 and the second electrode 3 are two electrodes in any electrode pair of the target sensor respectively; the Z direction is the depth direction, the X direction, the Y direction are two directions perpendicular to the Z direction, and X, Y, Z satisfies the right hand rule.
The average sensitivity of the layers of the measurement domain 1 is calculated according to the following formula:
wherein M is k S (I, j, k) is the sensitivity corresponding to the solving unit with coordinates (I, j, k) and is the average sensitivity of the kth layer, I 0 And I 1 Respectively the starting point coordinate and the end point coordinate of the appointed region of the kth layer in the X direction, J 0 And J 1 The start point coordinates and the end point coordinates of the designated region of the k-th layer in the Y direction, respectively.
S (i, j, k) is a specific element in the sensitivity matrix S, and S (i, j, k) can be known from the sensitivity matrix.
Preferably, the finite element meshing of the measurement domain 1 of the target sensor in three dimensions includes: and carrying out hexahedral mesh division on the measurement domain 1 of the target sensor in a three-dimensional space. Wherein, the convergence rate is high by adopting hexahedron calculation.
On the other hand, the embodiment of the invention also provides the acquisition system. The acquisition system includes: the system comprises a first solving module, a first calculating module, a searching module and a second calculating module. The first solving module is used for acquiring a sensitivity matrix of the measuring domain 1 of the target sensor in a three-dimensional space; the first calculation module is used for calculating average sensitivities respectively corresponding to the surface layers with different depths of the measurement domain 1 according to the sensitivity matrix; the searching module is used for obtaining the maximum value in the calculated average sensitivity corresponding to the surface layer of each depth of the measuring domain 1 and searching a target surface layer, wherein the ratio of the average sensitivity corresponding to the target surface layer to the maximum value is a preset ratio; the second calculation module is used for calculating the distance between the target surface layer and the surface of the target sensor to serve as the sensing depth of the target sensor.
The following specifically describes a specific flow of a method for acquiring a sensing depth of a co-planar capacitive sensor according to an embodiment of the present invention.
step 101: finite element meshing is performed on the measurement field 1 of the target sensor.
Illustratively, as shown in FIG. 2, the in-plane capacitive sensor includes: a first electrode 2, a second electrode 3 and a substrate 4. The first electrode 2 and the second electrode 3 are made of copper materials, the substrate 4 is made of FR-4 materials, shielding is arranged between the two electrodes, around the two electrodes and at the bottoms of the two electrodes, the shielding is made of copper materials, and the shielding is used for grounding when the coplanar capacitive sensor works.
The measuring domain 1 of the coplanar capacitive sensor is a cuboid, and the length, the width and the height of the measuring domain are 6.6cm, 3cm and 5cm respectively. In the three-dimensional space, the length direction of the measurement field 1 is set as the X direction, the width direction is set as the Y direction, and the height direction is set as the Z direction, i.e., the depth direction.
Dividing the length, width, and height of the measurement domain 1 equally by 1mm intervals, respectively, the total number of divisions i=66 in the X direction, the total number of divisions j=30 in the Y direction, and the total number of divisions k=50 in the Z direction of the measurement domain 1. The measurement domain 1 is divided into 50 layers in the depth direction, and is divided into i×j×k=99000 meshes, each of which is a solution unit, as shown in fig. 3.
Step 102: and acquiring a sensitivity matrix of the measurement domain 1 of the target sensor in a three-dimensional space based on a finite element analysis method.
Specifically, after the finite element meshing of the measurement domain 1 in step 101 is completed, firstly, the electric field distribution of the measurement domain 1 under the boundary condition that the first electrode 2 is excited and the second electrode 3 is grounded is solved, then, the electric field distribution of the measurement domain 1 under the boundary condition that the second electrode 3 is excited and the first electrode 2 is grounded is solved, and finally, the sensitivity matrix S of the coplanar sensor is obtained through calculation according to the formula (1).
In implementation, a three-dimensional model with the same size and material as the sensor in fig. 2 is built at COMSOL Multiphysics, the electric field distribution of the measuring field 1 of the coplanar capacitive sensor under the boundary condition that the first electrode 2 is excited and the second electrode 3 is grounded is solved by using a COMSOL Multiphysics steady-state calculation module, the electric field distribution of the measuring field 1 under the boundary condition that the second electrode 3 is excited and the first electrode 2 is grounded is calculated by using a formula (1), and then a sensitivity matrix S is obtained.
Wherein S is a sensitivity matrix;
a potential distribution of the measurement domain 1 when the first electrode 2 is excited and the second electrode 3 is grounded; />
A potential distribution of the measurement domain 1 when the second electrode 3 is excited and the first electrode 2 is grounded; v (V) 1 A voltage at which the first electrode 2 is energized; v (V) 2 A voltage at which the second electrode 3 is energized; I. j and K are the total number of divisions of the measurement domain 1 in the X direction, the Y direction, and the Z direction, respectively, and i, J, and K are the coordinates of the solution unit in the X direction, the Y direction, and the Z direction, respectively.
Step 2: and calculating the average sensitivity corresponding to each surface layer (1 st layer to K th layer) of different depths of the measuring domain 1 according to the sensitivity matrix.
In the present embodiment, the measurement domain 1 is divided into 50 layers in the depth direction, and accordingly, the sensitivity matrix also has 50 layers, and the average sensitivity M of each layer is calculated according to the formula (2) k ，k＝1,2,...K。
Wherein M is k S (I, j, k) is the sensitivity corresponding to the solving unit with coordinates (I, j, k) and is the average sensitivity corresponding to the kth layer, I 0 And I 1 Respectively the starting point coordinate and the end point coordinate of the appointed region of the kth layer in the X direction, J 0 And J 1 The start point coordinates and the end point coordinates of the designated region of the k-th layer in the Y direction, respectively.
In this embodiment, the average value corresponding to the kth layerThe sensitivity is the average of the sensitivity of the entire region of the kth layer, i.e. 0 ＝1，I 1 ＝66,J 0 ＝1，J 1 ＝30。
Step 3: obtaining the maximum value M in the calculated average sensitivity corresponding to the surface layer of each depth of the measuring domain 1 max 。
Wherein, according to the calculated average sensitivity corresponding to the surface layers of the respective depths, a change trend curve of the average sensitivity corresponding to the surface layers in the depth direction can be drawn, as shown in fig. 4. According to fig. 4, the average sensitivity of each facing layer gradually decreases in the depth direction.
Step 4: and searching a target surface layer (a gamma layer), wherein the ratio of the average sensitivity corresponding to the target surface layer to the maximum value is a preset ratio.
Specifically, the average sensitivity M corresponding to the target surface layer (the gamma-th layer) γ ＝3％M max 。
Step 5: the distance between the target surface layer and the surface of the target sensor is calculated as the sensing depth of the target sensor.
As shown in fig. 4, depth d of target surface layer (gamma-th layer) γ I.e. the sensing depth of the object sensor.
Those skilled in the art will appreciate that all or part of the flow of the methods of the embodiments described above may be accomplished by way of a computer program to instruct associated hardware, where the program may be stored on a computer readable storage medium. Wherein the computer readable storage medium is a magnetic disk, an optical disk, a read-only memory or a random access memory, etc.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention.
Claims (10)
1. A method for acquiring a sensing depth of a coplanar capacitive sensor, the method comprising:
acquiring the sensing depth of the target sensor according to the change of the sensitivity data of the measuring domain of the target sensor in the depth direction;
wherein the depth direction is a direction away from and perpendicular to a surface of the target sensor.
2. The acquisition method of claim 1, wherein the sensitivity data comprises: the surface layers of different depths of the measurement domain respectively correspond to the average sensitivity,
wherein the average sensitivity of the facing for each depth is the average of the sensitivities of all locations in the designated area of the facing.
3. The method of claim 2, wherein the designated area is a portion or all of the area on the facing.
4. A method of acquisition according to claim 2 or 3, characterized in that it comprises the steps of:
acquiring a sensitivity matrix of a measurement domain of the target sensor in a three-dimensional space;
calculating average sensitivities respectively corresponding to the surface layers with different depths of the measuring domain according to the sensitivity matrix;
obtaining the maximum value in the calculated average sensitivity corresponding to the surface layer of each depth of the measurement domain;
searching a target surface layer, wherein the ratio of the average sensitivity corresponding to the target surface layer to the maximum value is a preset ratio;
the distance between the target surface layer and the surface of the target sensor is calculated as the sensing depth of the target sensor.
5. The method of claim 4, wherein the predetermined ratio is 3%.
6. The acquisition method according to claim 4, characterized in that the measurement domain of the target sensor is subjected to finite element meshing in a three-dimensional space, and a sensitivity matrix of the measurement domain of the target sensor in the three-dimensional space is acquired based on a finite element analysis method.
7. The method of claim 6, wherein the sensitivity matrix is calculated according to the following formula:
wherein S is a sensitivity matrix;
a potential distribution of the measurement domain when the first electrode is energized and the second electrode is grounded; />
A potential distribution of the measurement domain when the second electrode is energized and the first electrode is grounded; v (V) 1 A voltage at which the first electrode is energized; v (V) 2 A voltage at which the second electrode is energized; I. j and K are the total number of divisions of the measurement domain in the X direction, the Y direction and the Z direction, and i, J and K are the coordinates of the solution unit in the X direction, the Y direction and the Z direction;
wherein the first electrode and the second electrode are two electrodes in any electrode pair of the target sensor respectively; the Z direction is the depth direction, the X direction, the Y direction are two directions perpendicular to the Z direction, and X, Y and Z satisfy the right hand rule.
8. The acquisition method according to claim 7, characterized in that the average sensitivity of each layer of the measurement domain is calculated according to the following formula:
wherein M is k S (I, j, k) is the sensitivity corresponding to the solving unit with coordinates (I, j, k) and is the average sensitivity corresponding to the kth layer, I 0 And I 1 Respectively the starting point coordinate and the end point coordinate of the appointed region of the kth layer in the X direction, J 0 And J 1 The start point coordinates and the end point coordinates of the designated region of the k-th layer in the Y direction, respectively.
9. The acquisition method according to claim 4, characterized in that the finite element meshing of the measurement domain of the target sensor in three-dimensional space comprises:
and carrying out hexahedral mesh division on the measurement domain of the target sensor in a three-dimensional space.
10. An acquisition system for sensing depth of a co-planar capacitive sensor, the acquisition system comprising:
the solving module is used for acquiring a sensitivity matrix of a measurement domain of the target sensor in a three-dimensional space;
the first calculation module is used for calculating average sensitivities respectively corresponding to the surface layers with different depths of the measurement domain according to the sensitivity matrix;
the searching module is used for obtaining the maximum value in the calculated average sensitivity corresponding to the surface layer of each depth of the measuring domain and searching a target surface layer, wherein the ratio of the average sensitivity corresponding to the target surface layer to the maximum value is a preset ratio;
a second calculation module for calculating a distance between the target surface layer and a surface of the target sensor as a sensing depth of the target sensor.
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