CN109855520B - Micro-nano precision measurement displacement sensor, system and preparation method - Google Patents

Abstract

The invention discloses a micro-nano precision measurement displacement sensor, which comprises a compliant mechanism with reverse gain, a displacement measurement electrode and a sensor shell for integral packaging; the compliant mechanism is connected to the sensor shell by adopting an integrated processing and forming technology, the head end of the compliant mechanism is provided with a measured displacement contact input end, and the tail end of the compliant mechanism is provided with an output end moving electrode; the displacement measuring electrode comprises a first electrode, a second electrode, a third electrode and a fourth electrode, the first electrode and the second electrode are respectively arranged above and below the left end of the moving electrode, the third electrode and the fourth electrode are respectively arranged above and below the right end of the moving electrode, the first electrode, the second electrode, the third electrode and the fourth electrode are fixedly connected with the sensor shell, the moving electrode, the first electrode, the second electrode, the third electrode and the fourth electrode jointly form two groups of differential displacement measuring circuits, and micro-nano displacement measurement is realized through an external reading processing circuit.

Description

A kind of micro-nano precision measurement displacement sensor, system and preparation method

technical field

The invention relates to the technical field of sensors, in particular to a micro-nano precision measuring displacement sensor.

Background technique

Displacement sensors can be divided into various types according to different measurement principles. Among them, capacitive displacement sensors are widely used in the displacement measurement of mechanisms; traditional capacitive sensors can achieve accurate displacement measurement by adjusting the installation and arrangement of electrodes; but For the measurement of micro-nano displacement, the traditional capacitive sensor cannot measure the displacement at the micro-nano level due to the large accuracy error. Therefore, to achieve accurate measurement of micro-nano displacement, not only the installation of capacitive electrodes has great requirements, but also And it also has great challenges for circuit design.

SUMMARY OF THE INVENTION

The invention provides a micro-nano precision measurement displacement sensor, a system and a preparation method, so as to solve the technical problem that the traditional sensor cannot accurately measure the micro-nano displacement, so as to realize the precise measurement of the micro-nano level displacement.

In order to solve the above technical problems, the embodiments of the present invention provide a micro-nano precision measurement displacement sensor, including a compliance mechanism with reverse gain, a displacement measurement electrode, and a sensor housing for integral packaging;

The compliance mechanism is connected to the sensor housing by integrated processing and molding technology, the head end of the compliance mechanism has a measured displacement contact input end, and the end of the compliance mechanism has an output end moving electrode;

The displacement measuring electrode includes a first electrode, a second electrode, a third electrode and a fourth electrode, the first electrode and the second electrode are respectively arranged above and below the left end of the moving electrode, the third electrode and the The fourth electrodes are respectively arranged above and below the right end of the moving electrode, the first electrode, the second electrode, the third electrode and the fourth electrode are all fixedly connected to the sensor housing, so the The moving electrodes together with the first and second electrodes and the third and fourth electrodes form two sets of differential displacement measurement circuits, and the micro-nano displacement measurement is realized by connecting an external reading processing circuit.

As a preferred solution, the moving electrode is a metal sheet.

Correspondingly, the embodiment of the present invention also provides a micro-nano precision measurement system, including a signal processing module, a display, and the sensor of the present invention;

The first electrode, the second electrode, the third electrode, the fourth electrode and the moving electrode are connected to the input end of the signal processing module through wires, and the output end of the signal processing module is connected to the input end of the display, The signal processing module is used to receive two sets of differential capacitor voltage signals, convert the signals into displacement magnitudes of the input terminals through analysis and processing, and transmit the displacement magnitudes to the display for display.

As a preferred solution, the measurement system further includes a server, the server has a control system interface, the output end of the signal processing module is connected to the control system interface, and the displacement can be controlled through the server, Realize the function of human-computer interaction.

Correspondingly, an embodiment of the present invention also provides a method for preparing the sensor of the present invention, comprising:

Optimize the preparation of the geometric model, use a rectangular plate to divide the unit mesh, and use the SIMP method to build the model for the divided mesh;

Optimize and iterate the established model to obtain a compliant mechanism with maximized reverse gain;

The compliant mechanism is fixedly connected to the sensor housing by using integrated processing and molding technology;

Four displacement measuring electrodes are arranged on the sensor housing, and the four displacement measuring electrodes are respectively arranged on the upper and lower left ends and the upper and lower right ends of the moving electrodes of the compliance mechanism.

As a preferred solution, the established model is:

find(x ₁ ,x ₂ ,...,x _n )

min u _out /u _in

stV/V ₀ =f

In the formula: x _n (n=1,2,…,,n) is the element density of the design area, u _out is the displacement of the output end of the compliance mechanism, u _in is the displacement of the input end of the compliance mechanism, v is the current volume of the design area, v ₀ is the initial volume of the design area, and f is the allowed material volume fraction to be retained.

As a preferred solution, the optimization iteration uses an optimization criterion algorithm to perform the optimization iteration.

As a preferred solution, the length and width of the rectangular plate vary according to the application and the size of the measured displacement model.

Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

By using a compliant mechanism with reverse gain, the technical problem that traditional sensors cannot accurately measure the micro-nano displacement can be solved, so that the micro-nano level displacement can be accurately measured.

Description of drawings

FIG. 1 is a schematic structural diagram of a micro-nano precision displacement measurement system in an embodiment of the present invention;

Wherein, the reference signs of the drawings in the description are as follows:

1. Compliant mechanism with reverse gain, 2. Displacement measuring electrode, 3. Sensor housing, 4. The measured displacement contacts the input end, 5. The output end moves the electrode.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Please refer to FIG. 1 , a preferred embodiment of the present invention provides a micro-nano precision measurement displacement sensor, including a compliance mechanism 1 with reverse gain, a displacement measurement electrode 2 and a sensor housing 3 for integral encapsulation;

The compliance mechanism 1 is connected to the sensor housing 3 by means of integrated processing and molding technology. ;

The displacement measuring electrode 2 includes a first electrode, a second electrode, a third electrode and a fourth electrode. The first electrode and the second electrode are respectively arranged above and below the left end of the moving electrode 5. The electrode and the fourth electrode are respectively arranged above and below the right end of the moving electrode 5, and the first electrode, the second electrode, the third electrode and the fourth electrode are all fixedly connected to the sensor housing 3, the moving electrode 5 together with the first and second electrodes and the third and fourth electrodes constitute two sets of differential displacement measurement circuits, which can realize micro-nano displacement measurement by connecting an external reading processing circuit.

In this embodiment, the moving electrode 5 is a metal sheet.

Correspondingly, a preferred embodiment of the present invention also provides a micro-nano precision measurement system, including a signal processing module, a display, and the sensor of the present invention;

The first electrode, the second electrode, the third electrode, the fourth electrode and the moving electrode 5 are connected to the input end 4 of the signal processing module through wires, and the output end of the signal processing module is connected to the input end of the display. 4 is connected, the signal processing module is used to receive two sets of differential capacitor voltage signals, convert the signal into the displacement size of the input terminal 4 through analysis and processing, and transmit the displacement size to the display for display.

In this embodiment, the measurement system further includes a server, the server has a control system interface, the output end of the signal processing module is connected to the control system interface, and the displacement size can be measured by the server. control, realize the function of human-computer interaction.

Correspondingly, a preferred embodiment of the present invention also provides a method for preparing the sensor of the present invention, comprising:

Optimize the preparation of the geometric model, use a rectangular plate to divide the unit mesh, and use the SIMP method to build the model for the divided mesh;

Optimize and iterate the established model to obtain a compliant mechanism with maximized reverse gain;

The compliant mechanism is fixedly connected to the sensor housing by using integrated processing and molding technology;

Four displacement measuring electrodes are arranged on the sensor housing, and the four displacement measuring electrodes are respectively arranged on the upper and lower left ends and the upper and lower right ends of the moving electrodes of the compliance mechanism.

In this embodiment, the established model is:

find(x ₁ ,x ₂ ,...,x _n )

min u _out /u _in

stV/V ₀ =f

In the formula: x _n (n=1,2,…,,n) is the element density of the design area, u _out is the displacement of the output end of the compliance mechanism, u _in is the displacement of the input end of the compliance mechanism, v is the current volume of the design area, v ₀ is the initial volume of the design area, and f is the allowed material volume fraction to be retained.

In this embodiment, the optimization iteration is performed using an optimization criterion algorithm to perform the optimization iteration.

In this embodiment, the length and width of the rectangular plate vary according to the application and the size of the measured displacement model.

The present invention will be described in detail below with reference to specific embodiments.

The technical solution adopted in the present invention is a method combining mechanical structure displacement amplification and displacement detection, which is mainly divided into three parts:

The first is the compliance mechanism, which is different from the way traditional mechanisms transmit motion, force and energy. The compliance mechanism is realized by elastic deformation of its own structural components. In the present invention, the compliance mechanism is designed by the topology optimization method. Constrained by the volume of the mechanism, a displacement amplifying mechanism with a given reverse gain coefficient is obtained. The design steps are as follows:

1. Optimization model preparation

The optimized geometric model adopts a rectangular plate with length and width of a and b respectively (a and b are given according to the application of the sensor and the size of the measured displacement model), and the finite element grid is divided, and the SIMP method is used for the divided grid. Modeled as follows:

find(x ₁ ,x ₂ ,...,x _n )

min u _out /u _in

stV/V ₀ =f

In the formula: x _n (n=1,2,…,,n) is the element density of the design area, u _out is the displacement of the output end of the compliance mechanism, u _in is the displacement of the input end of the compliance mechanism, v is the current volume of the design area, v ₀ is the initial volume of the design area, and f is the allowed material volume fraction to be retained.

2. Optimization calculation

The OC algorithm is used to optimize and iterate the above model, and a compliant mechanism with maximized reverse gain is obtained, and the compliant mechanism shown in Figure 1 is obtained by extracting the optimized model. The mechanism is composed of a single part and has a definite gain relationship between the displacement input end and the output end. The advantage of this design is that the movement of the compliant mechanism does not require lubrication, and at the same time, the error caused by the installation and positioning gap is avoided, and the displacement from the input end to the output is greatly improved. The transfer efficiency and accuracy of the end-point provide a guarantee for the measurement of micro-nano displacement;

The second is displacement measurement. The end of the compliance mechanism is bonded with a metal sheet, and its movement mode is the same as that of the output end under the action of input. The metal sheet is used as the moving electrode of the capacitor. The upper and lower first electrodes and second electrodes on the left end) and the fixed electrodes (the third electrodes and fourth electrodes respectively arranged on the upper and lower sides of the moving electrodes) together constitute two sets of differential capacitors. The four fixed electrodes and the moving electrode 5 are led out to the outside of the sensor through wires and connected to the external signal processing module;

The third is the external signal processing module: this module is mainly used to detect the changes of the two sets of differential capacitor voltage signals, and through analysis and processing, the signal is converted into the displacement of the input terminal and displayed. At the same time, the signal can also be It is further sent to the control system to facilitate the control of the input displacement. Its signal processing process is:

When ε _r and S of the capacitive sensor are constants and the distance between the two plates is d ₀ , it can be known that the initial capacitance C ₀ of the capacitor is:

When the displacement of the input end of the compliance mechanism changes, causing the displacement of the output end to change, the plate distance between the two polar plates of the capacitor changes, causing the capacitance to change. The total capacitance C of the capacitor after the change is:

It is composed of the moving electrode 5, the fixed electrode (the first electrode and the second electrode respectively arranged above and below the left end of the moving electrode) and the fixed electrode (the third electrode and the fourth electrode respectively arranged above and below the right end of the moving electrode) The two groups of differential capacitors are expanded from the above formula, and the relationship between the change of capacitance under the differential capacitor and the change of the distance between the capacitor electrodes is:

Since there are two sets of differential capacitors, the distance variation Δd between the two electrodes can be calculated separately, and the average value of the two Δd is taken as the displacement variation of the output end of the compliance mechanism to reduce errors. The displacement of the input end, that is, the measured displacement, can be obtained by calculating the average displacement through the reverse gain coefficient of the compliance mechanism.

Using this sensor to measure micro-nano displacement has certain guiding significance for designing a precise positioning mechanism with a specific movement mode; the compliant mechanism obtained by the above design method is processed and manufactured in an integrated manner with the sensor shell, and is also manufactured in an integrated manner. There are four fixed electrodes, and the integrated manufacturing ensures the connection between the various components of the sensor, there is no installation gap, and the overall accuracy is improved. The input of the measured displacement; the five electrodes inside the sensor are respectively drawn out of wires and connected to the external data processing module to realize the collection of displacement data; in the process of displacement measurement, the sensor needs to be properly installed to realize the measured displacement. The input acting on the membrane in the displacement direction.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the protection scope of the present invention. . It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims (8)

1. a micro-nano precision measurement displacement sensor, is characterized in that, comprises the compliant mechanism with reverse gain, displacement measurement electrode and the sensor housing for integral encapsulation; The compliance mechanism is connected to the sensor housing by integrated processing and molding technology, the head end of the compliance mechanism has a measured displacement contact input end, and the end of the compliance mechanism has an output end moving electrode; The displacement measuring electrode includes a first electrode, a second electrode, a third electrode and a fourth electrode, the first electrode and the second electrode are respectively arranged above and below the left end of the moving electrode, the third electrode and the The fourth electrodes are respectively arranged above and below the right end of the moving electrode, the first electrode, the second electrode, the third electrode and the fourth electrode are all fixedly connected to the sensor housing, so the The moving electrodes together with the first and second electrodes and the third and fourth electrodes form two sets of differential displacement measurement circuits, and the micro-nano displacement measurement is realized by connecting an external reading processing circuit. 2. The sensor of claim 1, wherein the moving electrode is a thin metal sheet. 3. A micro-nano precision measurement system, comprising a signal processing module, a display and the sensor according to any one of claims 1 or 2; The first electrode, the second electrode, the third electrode, the fourth electrode and the moving electrode are connected to the input end of the signal processing module through wires, and the output end of the signal processing module is connected to the input end of the display, The signal processing module is used to receive two sets of differential capacitor voltage signals, convert the signals into displacement magnitudes of the input terminals through analysis and processing, and transmit the displacement magnitudes to the display for display. 4. The measurement system according to claim 3, wherein the measurement system further comprises a server, the server has a control system interface, the output end of the signal processing module is connected to the control system interface, and can The displacement size is controlled by the server to realize the human-computer interaction function. 5. A method for preparing a sensor as claimed in any one of claims 1 to 2, comprising: Optimize the preparation of the geometric model, use a rectangular plate to divide the unit mesh, and use the SIMP method to build the model for the divided mesh; Optimize and iterate the established model to obtain a compliant mechanism with maximized reverse gain; The compliant mechanism is fixedly connected to the sensor housing by using integrated processing and molding technology; Four displacement measuring electrodes are arranged on the sensor housing, and the four displacement measuring electrodes are respectively arranged on the upper and lower left ends and the upper and lower right ends of the moving electrodes of the compliance mechanism. 6. preparation method as claimed in claim 5, is characterized in that, described established model is: find(x ₁ ,x ₂ ,...,x _n ) min u _out /u _in stV/V ₀ =f Where: x _n (n=1,2,…,n) is the element density of the design area, u _out is the displacement of the output end of the compliance mechanism, u _in is the displacement of the input end of the compliance mechanism, v is the current volume of the design area, v ₀ is the initial volume of the design area, and f is the volume fraction of the material allowed to remain. 7 . The preparation method according to claim 5 , wherein the optimization iteration is performed by using an optimization criterion algorithm to perform the optimization iteration. 8 . 8 . The preparation method according to claim 5 , wherein the length and width of the rectangular plate are changed according to the application and the size of the measured displacement model. 9 .

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