Variable-area capacitive sensor displacement measurement method for suppressing interference

Abstract

The invention discloses a variable-area capacitive sensor displacement measurement method for suppressing interference, and relates to the technical field of precision displacement detection, and the method comprises the steps: S1, obtaining a differential capacitor array through a variable-area capacitive sensor; s2, acquiring a capacitance change signal by using the differential capacitor array; and S3, performing differential processing on the capacitance change signal to obtain a displacement measurement result of the variable-area capacitive sensor. According to the invention, a plurality of groups of differential capacitor pairs are arranged in the same direction, and differential output is carried out after odd-even grouping parallel connection, so that the output signal of the sensor is linearly increased along with the increase of the number of the differential capacitor pairs, and the measurement sensitivity is effectively improved. The structure not only can make quick and accurate response to infinitesimal displacement change, but also can realize higher-precision detection capability on the premise of not obviously increasing system complexity.

Description

Technical Field

[0001] The present invention relates to the technical field of precision displacement detection, and in particular to a displacement measurement method of a variable-area capacitive sensor for suppressing interference. Background Art

[0002] Capacitive sensors are common sensing devices that detect changes in capacitance to reflect measured physical quantities (such as displacement, pressure, acceleration, etc.). Their operating principle is to exploit changes in the measured object to cause changes in the geometric parameters of the capacitor (such as plate area, spacing, or dielectric properties), resulting in changes in capacitance. Due to their simple structure, non-contact measurement, low power consumption, and fast response, capacitive sensors have found widespread application in a variety of fields, including consumer electronics, industrial control, medical equipment, and aerospace.

[0003] Among various capacitive sensors, variable-area capacitive sensors are often used for precision displacement measurement due to their high sensitivity to displacement changes. These sensors typically consist of two metal plates: one fixed and the other movable. When an external physical quantity acts on the movable plate, the overlapping area between the two plates changes, causing a corresponding change in capacitance. By measuring this capacitance change, the magnitude of the measured displacement can be deduced, enabling non-contact, high-precision detection. However, in practical applications, traditional single-capacitive sensors have numerous limitations. Because they rely solely on a single capacitance unit for measurement, the output signal amplitude is small and easily affected by parasitic capacitance and environmental noise, resulting in a low overall signal-to-noise ratio, limiting measurement accuracy and stability. Furthermore, these sensors lack effective common-mode rejection mechanisms and are sensitive to external interference factors such as temperature drift and power supply voltage fluctuations. Performance degradation can occur over long-term use, impacting system reliability.

[0004] Therefore, there is an urgent need for a variable area capacitive sensor displacement measurement method for suppressing interference to meet the needs of the field of precision displacement detection. Summary of the Invention

[0005] The purpose of the present invention is to propose a displacement measurement method of a variable-area capacitive sensor for suppressing interference. By arranging multiple capacitor pairs in the same plane and the same direction and processing data differentially, the sensitivity of the system is improved and the anti-interference ability is enhanced.

[0006] To achieve the above object, the present invention provides a displacement measurement method of a variable-area capacitive sensor for suppressing interference, comprising the following steps: S1. Obtain a differential capacitance array using a variable area capacitive sensor; S2. Obtaining a capacitance change signal using the differential capacitor array; S3. Perform differential processing on the capacitance change signal to obtain a displacement measurement result of the variable area capacitive sensor.

[0007] Optionally, the variable area capacitive sensor includes a plurality of differential capacitor pairs, and each of the differential capacitor pairs is composed of a plurality of fixed electrode plates and moving electrode plates.

[0008] Optionally, S1 uses a variable area capacitive sensor to obtain a differential capacitance array, including: Based on the variable area capacitive sensor, a plurality of differential capacitor pairs are arranged along a straight line on the same plane, wherein the moving plates of the plurality of differential capacitor pairs are integrated and arranged on the same sliding layer, and the moving plates of the plurality of capacitor pairs move synchronously under the action of an external force; The moving electrode plates of the odd groups and the moving electrode plates of the even groups in the plurality of differential capacitor pairs are arranged alternately to obtain a differential capacitor array.

[0009] Optionally, S2, using the differential capacitor array to obtain a capacitance change signal, includes: Connecting the moving plates of the odd-numbered groups in the differential capacitor array in parallel to obtain a first output end; Connecting the moving plates of the even group in the differential capacitor array in parallel to obtain a second output end; Obtaining a total capacitance change of an odd array and a total capacitance change of an even array based on the first output end and the second output end according to a displacement of a power plate of the variable-area capacitive sensor under an external force; The total capacitance change of the odd array and the total capacitance change of the even array are acquired as capacitance change signals.

[0010] Optionally, the calculation formula for the change in total capacitance of the odd-numbered array is as follows:

[0011] Among them, ∆ C odd is the total capacitance change of the odd array, odd is an odd number, C R,i For the i The capacitance formed by the moving plate in the odd-numbered group and the fixed plate on the right, C L,i For the i The capacitance formed by the moving plate in the odd-numbered group and the fixed plate on the left, N odd is the number of odd-number differential capacitor pairs, k is the proportionality coefficient, ∆ x is the displacement of the moving plate under the action of external force.

[0012] Optionally, the calculation formula for the total capacitance change of the even array is as follows:

[0013] Among them, ∆ C even is the total capacitance change of the even array, even is an even number, C R,i For the i The capacitance formed by the moving plate in the odd-numbered group and the fixed plate on the right, C L,i For the i The capacitance formed by the moving plate in the odd-numbered group and the fixed plate on the left, N even is the number of differential capacitor pairs in an even array, k is the proportionality coefficient, ∆ x is the displacement of the moving plate under the action of external force.

[0014] Optionally, S3, performing differential processing on the capacitance change signal to obtain a displacement measurement result of the variable-area capacitive sensor, includes: performing differential processing on the capacitance change signal to obtain a capacitance change amount as a differential output; Based on the capacitance change of the differential output and the sensitivity, a displacement measurement result of the variable area capacitive sensor is obtained.

[0015] Optionally, differential processing is performed on the capacitance change signal to obtain a capacitance change amount of the differential output, and the calculation formula is as follows:

[0016] Among them, ∆ C diff is the capacitance change of the differential output, ∆ C odd is the total capacitance change of the odd array, ∆ C even is the total capacitance change of the even array, N is the number of differential capacitor pairs, k is the proportionality coefficient, ∆ x is the displacement of the moving plate under the action of external force.

[0017] Optionally, the sensitivity calculation formula is as follows:

[0018] in, S is the sensitivity, ∆ C diff is the capacitance change of the differential output, ∆ x is the displacement of the moving plate under the action of external force.

[0019] Compared with the closest prior art, the present invention has the following beneficial effects: This invention incorporates innovative improvements in structural design and signal processing, significantly enhancing the sensor's overall performance. By arranging multiple differential capacitor pairs in the same direction and employing a process that parallels them in odd-even groups before performing differential output, the sensor's output signal increases linearly with the number of differential capacitor pairs, effectively improving measurement sensitivity. This structure not only enables rapid and accurate response to minute displacement changes, but also achieves higher-precision detection capabilities without significantly increasing system complexity.

[0020] Furthermore, due to its differential output mechanism, the present invention exhibits excellent immunity to common-mode interference factors such as temperature drift, power supply voltage fluctuations, and material thermal expansion. These external interferences typically have similar effects on all capacitor cells, but they are offset by the differential output process, significantly improving system stability and long-term reliability. This makes it particularly suitable for applications with complex working environments and high stability requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a flow chart of a method for measuring displacement of a variable-area capacitive sensor for suppressing interference according to an embodiment of the present invention; Figure 2 A schematic diagram of a capacitive sensor plate according to an embodiment of the present invention; Figure 3 This is a structural diagram of the differential bian3 area capacitance sensor proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] The terms used in the embodiments of the present invention are only used to explain the specific embodiments of the present invention and are not intended to limit the present invention.

[0025] like Figure 1 As shown, an embodiment of the present invention provides a variable area capacitive sensor displacement measurement method for suppressing interference, comprising: S1. Obtain a differential capacitance array using a variable area capacitive sensor; When using variable area capacitive sensors to obtain differential capacitance arrays, they need to be arranged in a straight line on the same plane. N Each pair of differential capacitors consists of two fixed plates and one movable plate, and all movable plates are integrated into the same sliding layer and can move synchronously, while the odd and even groups of movable plates are staggered to form a symmetrical physical layout. This process is achieved by increasing the number of differential capacitor pairs. N , laying the foundation for subsequent sensitivity improvement, and the symmetrical layout design helps to suppress common-mode interference in the future, providing structural support for the high precision and high stability of the overall measurement system.

[0026] S2. Obtaining a capacitance change signal using the differential capacitor array; When acquiring capacitance change signals using the differential capacitor array constructed above, all odd-numbered moving plates are connected in parallel as output terminal A, and all even-numbered moving plates are connected in parallel as output terminal B. When the moving plates move due to displacement, the area facing the fixed plates changes, resulting in corresponding capacitance change signals at terminals A and B, respectively. By connecting multiple capacitor pairs in parallel, the output signal amplitude is greater than that of traditional single-capacitive sensors, reducing the impact of parasitic capacitance and environmental noise, improving the signal-to-noise ratio, and providing a more reliable signal source for subsequent precise measurements.

[0027] S3. Perform differential processing on the capacitance change signal to obtain a displacement measurement result of the variable area capacitive sensor.

[0028] The capacitance change signals obtained from output terminals A and B are differentially processed, that is, the difference between the two signals is calculated to obtain the final capacitance change, and then the displacement measurement result is derived according to the sensitivity formula. This differential processing process makes the system sensitivity and the number of differential capacitance pairs N ( N is an even number), significantly improving the measurement sensitivity and enabling a quick and accurate response to tiny displacement changes. At the same time, common-mode interferences such as temperature drift and power supply voltage fluctuations are completely offset in the differential processing, effectively enhancing the system's anti-interference capability, ensuring the accuracy and stability of the measurement results, and improving the long-term reliability of the system.

[0029] Furthermore, the variable area capacitive sensor includes a plurality of capacitor pairs, and each of the capacitor pairs is composed of a plurality of fixed electrodes and moving electrodes.

[0030] Specifically, the differential variable area capacitance sensor consists of a fixed electrode and a moving electrode, and the initial capacitance value is C 0 is:

[0031] in, ε is the total dielectric constant, A is the area facing the two plates, d is the plate spacing; The variable area capacitive sensor includes a plurality of capacitor pairs, and each capacitor pair consists of two fixed plates and one moving plate.

[0032] As a possible implementation, in the above embodiment, step S1 may specifically include the following steps: Based on the variable area capacitive sensor, a plurality of differential capacitor pairs are arranged along a straight line on the same plane, wherein the moving plates of the plurality of differential capacitor pairs are integrated and arranged on the same sliding layer, and the moving plates of the plurality of capacitor pairs move synchronously under the action of an external force; The moving electrode plates of the odd groups and the moving electrode plates of the even groups in the plurality of differential capacitor pairs are arranged alternately to obtain a differential capacitor array.

[0033] Specifically, all the moving pole plates are integrated on the same sliding layer and can move synchronously under the action of external force.

[0034] In the initial state, the moving electrode is located in the center, and the area facing the two fixed electrodes on the left and right is equal. Figure 2 As shown, the corresponding capacitance value is: C L = C R = C 0 in, C L is the capacitance formed by the moving plate and the left fixed plate, C R It is the capacitance formed by the moving plate and the fixed plate on the right.

[0035] Arranged along a straight line on the same plane N The differential capacitor array is constructed by staggering the odd and even groups of differential capacitors, with a symmetrical physical layout to achieve spatial periodic sampling of the target signal.

[0036] As a possible implementation, in the above embodiment, step S2 may specifically include the following steps: S2-1, connecting the moving plates of the odd-numbered groups in the differential capacitor array in parallel to obtain a first output end; S2-2, connecting the moving plates of the even group in the differential capacitor array in parallel to obtain a second output end; S2-3. Obtain a total capacitance change of the odd array and a total capacitance change of the even array based on the first output end and the second output end according to the displacement of the power plate under the action of the external force, wherein the capacitance change corresponding to the first output end is the total capacitance change of the odd array, and the capacitance change corresponding to the second output end is the total capacitance change of the even array; S2-4. Obtain the total capacitance change of the odd array and the total capacitance change of the even array as capacitance change signals.

[0037] Specifically, all odd-numbered moving plates are connected in parallel to form one output terminal A; all even-numbered moving plates are connected in parallel to form another output terminal B. When the moving plate moves to the right ∆ x , causing the facing area to change, which in turn causes the capacitance to change. The calculation formula is as follows:

[0038] Among them, ∆ C is the capacitance change, k is the proportionality factor (depending on plate size, dielectric constant, etc.), which represents the change in capacitance per unit displacement, ∆ x is the displacement of the moving plate under the action of external force.

[0039] Total capacitance change of odd group ∆ C odd for:

[0040] in, odd is an odd number, C R,i For the i The capacitance formed by the moving plate in the odd-numbered group and the fixed plate on the right, C L,i For the i The capacitance formed by the moving plate in the odd-numbered group and the fixed plate on the left, N odd is the number of odd-number differential capacitor pairs.

[0041] Total capacitance change of even array ∆ C even for:

[0042] in, even is an even number, Neven is the number of differential capacitor pairs in an even array.

[0043] As a possible implementation, in the above embodiment, step S3 may specifically include the following steps: S3-1, performing differential processing on the capacitance change signal to obtain a capacitance change amount as a differential output; S3-2. Obtain a displacement measurement result of the variable-area capacitive sensor based on the capacitance change of the differential output in combination with sensitivity.

[0044] Specifically, the A and B signals are differentially processed to obtain the final output signal, such as Figure 3 shown.

[0045] N is an even number, then: N odd = N even = N / 2; Perform differential processing on the final output signal to obtain the capacitance change ∆ of the differential output C diff for:

[0046] Sensitivity S It is defined as the ratio of the change in output signal to the change in input displacement:

[0047] Substituting the above results:

[0048] It can be seen that the sensitivity is related to the number of differential capacitor pairs. N Using more differential capacitor pairs can significantly improve the sensitivity, and the sensitivity increases linearly with each additional group.

[0049] Introducing common mode interference δC , indicating that all capacitor pairs are subject to the same external disturbance (such as temperature drift, voltage fluctuation, etc.). N For example, for an even number,

[0050] Among them, ∆ C cm is the change in common-mode capacitance.

[0051] The total capacitance change of the odd array is:

[0052] The total capacitance change of the even array is:

[0053] The differential output is:

[0054] It can be seen that the common mode interference term δC They are completely offset in the differential process, achieving good anti-interference ability.

[0055] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0056] The present invention is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0057] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0058] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A displacement measurement method for a variable area capacitive sensor for suppressing interference, characterized in that: include: S1. Using a variable area capacitive sensor to obtain a differential capacitance array; The variable area capacitive sensor includes a plurality of differential capacitor pairs, each of which is composed of a plurality of fixed electrodes and a plurality of moving electrodes; S2. Obtaining a capacitance change signal using the differential capacitor array; S2. Obtaining a capacitance change signal using the differential capacitor array, including: Connecting the moving plates of the odd-numbered groups in the differential capacitor array in parallel to obtain a first output end; Connecting the moving plates of the even group in the differential capacitor array in parallel to obtain a second output end; Obtaining a total capacitance change of an odd array and a total capacitance change of an even array based on the first output end and the second output end according to a displacement of a power plate of the variable-area capacitive sensor under an external force; Acquire the total capacitance change of the odd array and the total capacitance change of the even array as capacitance change signals; S3. Perform differential processing on the capacitance change signal to obtain a displacement measurement result of the variable area capacitive sensor.

2. The method for measuring displacement of a variable area capacitive sensor for suppressing interference according to claim 1, characterized in that: S1. Using a variable area capacitive sensor to obtain a differential capacitance array, including: Based on the variable area capacitive sensor, a plurality of differential capacitor pairs are arranged along a straight line on the same plane, wherein the moving plates of the plurality of differential capacitor pairs are integrated and arranged on the same sliding layer, and the moving plates of the plurality of capacitor pairs move synchronously under the action of an external force; The moving electrode plates of the odd groups and the moving electrode plates of the even groups in the plurality of differential capacitor pairs are arranged alternately to obtain a differential capacitor array.

3. The method for measuring displacement of a variable area capacitive sensor for suppressing interference according to claim 1, wherein: The calculation formula for the total capacitance change of the odd-numbered array is as follows: Among them, ∆ C odd is the total capacitance change of the odd array, odd is an odd number, C R,i For the i The capacitance formed by the moving plate in the odd-numbered group and the fixed plate on the right, C L,i For the i The capacitance formed by the moving plate in the odd-numbered group and the fixed plate on the left, N odd is the number of odd-number differential capacitor pairs, k is the proportionality coefficient, ∆ x is the displacement of the moving plate under the action of external force.

4. The method for measuring displacement of a variable area capacitive sensor for suppressing interference according to claim 1, wherein: The calculation formula for the total capacitance change of the even array is as follows: Among them, ∆ C even is the total capacitance change of the even array, even is an even number, C R,i For the i The capacitance formed by the moving plate in the odd-numbered group and the fixed plate on the right, C L,i For the i The capacitance formed by the moving plate in the odd-numbered group and the fixed plate on the left, N even is the number of differential capacitor pairs in an even array, k is the proportionality coefficient, ∆ x is the displacement of the moving plate under the action of external force.

5. The method for measuring displacement of a variable area capacitive sensor for suppressing interference according to claim 1, characterized in that: S3. performing differential processing on the capacitance change signal to obtain a displacement measurement result of the variable-area capacitive sensor, including: performing differential processing on the capacitance change signal to obtain a capacitance change amount as a differential output; Based on the capacitance change of the differential output and the sensitivity, a displacement measurement result of the variable area capacitive sensor is obtained.

6. The method for measuring displacement of a variable area capacitive sensor for suppressing interference according to claim 5, characterized in that: The capacitance change signal is differentially processed to obtain the capacitance change of the differential output, which is calculated as follows: Among them, ∆ C diff is the capacitance change of the differential output, ∆ C odd is the total capacitance change of the odd array, ∆ C even is the total capacitance change of the even array, N is the number of differential capacitor pairs, k is the proportionality coefficient, ∆ x is the displacement of the moving plate under the action of external force.

7. The method for measuring displacement of a variable area capacitive sensor for suppressing interference according to claim 5, characterized in that: The sensitivity calculation formula is as follows: in, S is the sensitivity, ∆ C diff is the capacitance change of the differential output, ∆ x is the displacement of the moving plate under the action of external force.

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