CN-121994120-A - Method for realizing XYZ displacement measurement on grid sensor in same plane

CN121994120ACN 121994120 ACN121994120 ACN 121994120ACN-121994120-A

Abstract

The invention discloses a method for realizing XYZ displacement measurement on a grid sensor in the same plane, belonging to the technical field of measurement and sensing, the planar time grating sensor comprises a movable ruler substrate and a fixed ruler substrate, wherein an excitation electrode is arranged on the fixed ruler substrate, and an induction electrode is arranged on the movable ruler substrate. And carrying out phase detection processing on the traveling wave signals output by the movable ruler matrix relative to the fixed ruler matrix when moving in the XY plane, thereby realizing displacement measurement in the XY direction. When the movable rule base body is displaced along the Z direction to cause the capacitance change, the amplitude of the displacement output signal along the Z direction is changed, so that an amplitude-modulated alternating current signal is formed, and the alternating current signal is solved, so that the displacement value of the movable rule base body along the Z direction is obtained. The invention realizes displacement measurement by utilizing the phase and the amplitude of the output signal of the planar time grating sensor, can realize simultaneous measurement of three degrees of freedom of XYZ, has simple structure and high measurement precision, and is suitable for multi-degree-of-freedom precision displacement measurement occasions such as precision machine tools, positioning platforms and the like.

Inventors

PENG KAI
XU XIAOHU
TIAN YUXIN
WANG HEWEN
FAN XINGCHEN

Assignees

重庆理工大学

Dates

Publication Date: 20260508
Application Date: 20260407

Claims (7)

1. The method for realizing XYZ displacement measurement on the grid sensor in the same plane comprises a movable ruler substrate and a fixed ruler substrate which are arranged in parallel up and down with gaps, wherein a plurality of excitation electrodes with the same shape and size and the same interval are arranged on the upper surface of the fixed ruler substrate, the excitation electrodes in the X direction are arranged in a staggered mode, a plurality of excitation groups formed by the arrangement of the excitation electrodes in the X direction are correspondingly connected with a plurality of excitation groups formed by the arrangement of the excitation electrodes in the Y direction, so that A, B, C, D four-phase excitation electrode groups are formed, four induction electrodes A, B, C, D arranged in a 2X 2 matrix are arranged on the lower surface of the movable ruler substrate, the shape and the size of each induction electrode are the same, the distance between adjacent induction electrodes is the same, the induction electrodes on the movable ruler substrate are opposite to the excitation electrodes on the fixed ruler substrate, and the method is characterized in that: When displacement measurement is carried out, sinusoidal excitation signals S + =A 0 sin(ωt)、C + =A 0 cos(ωt)、S - =-A 0 sin(ωt)、C - =-A 0 cos(ωt), with the same amplitude and frequency and phase difference pi/2 are sequentially applied to A, B, C, D four-phase excitation electrode groups, wherein A 0 is the amplitude of the applied excitation signals, omega is the frequency of the applied excitation signals, and t is time; When the movable ruler substrate moves on the XY plane, the sensing electrodes A, B, C, D respectively output displacement measurement signals U A 、U B 、U C 、U D , obtain displacement output signals U X in the X direction and displacement output signals U Y in the Y direction through calculation, and further calculate the phase values of the displacement output signals U X and U Y to obtain displacement values X in the X direction and displacement values Y in the Y direction; When the movable ruler substrate moves along the Z direction, the sensing electrodes A, B, C, D respectively output displacement measurement signals U A 、U B 、U C 、U D , and because capacitive coupling is formed between the sensing electrodes and the exciting electrodes, the sensing voltage signals generated by the sensing electrodes are related to the capacitance values, and the displacement output signals U Z in the Z direction are expressed as: Wherein A m is the amplitude which has a function relation with the capacitance value, and the amplitude is the same as the amplitude of the U X and U Y displacement output signals obtained by the calculation at the moment; the phase of the output signal is related to the position of the movable ruler matrix on the XY plane; When the capacitance changes due to the displacement of the movable ruler matrix along the Z direction, the amplitude of the displacement output signal U Z along the Z direction changes to form an amplitude modulated alternating current signal, the alternating current signal is synchronously demodulated after being amplified and modulated into a direct current component through a filter circuit to obtain a direct current voltage signal in direct proportion to the capacitance change, the direct current voltage signal is acquired through an analog-to-digital converter to obtain a corresponding digital signal, and the displacement value of the movable ruler matrix along the Z direction is obtained according to the proportional relation between the pre-calibrated digital signal and the displacement value along the Z direction.
2. The method for realizing XYZ displacement measurement on the grid sensor in the same plane as that of claim 1, wherein the excitation electrodes are arranged in parallel along the upper surface of the fixed-length substrate, each row of excitation electrodes is composed of n identical square excitation pole pieces uniformly distributed along the X direction, the distance I 2 between every two adjacent square excitation pole pieces is larger than the width I 1 of one square excitation pole piece, the distance between every two adjacent rows of excitation electrodes along the Y axis direction is (I 2 -I 1 )/2, the starting positions along the X direction are staggered by (I 2 +I 1 )/2, the starting positions along the X direction of the odd-numbered row excitation electrodes are the same, the starting positions along the X direction of the even-numbered row excitation electrodes are the same, and n=4k 1 、m＝4k 2 ,k 1 、k 2 is a positive integer; In the excitation electrode array formed by all odd-numbered excitation electrodes, all the excitation electrodes in each row are respectively connected to form a row excitation group, thereby forming m row excitation groups, and from the first row, each four rows are respectively called a Y1 row excitation group, a Y2 row excitation group, a Y3 row excitation group and a Y4 row excitation group in a cycle; In the excitation electrode array formed by all even-numbered row excitation electrodes, all the excitation electrodes in each column are respectively connected to form column excitation groups, thereby forming n column excitation groups; All X1 column excitation groups and all Y1 row excitation groups are connected to form an A-phase excitation electrode group, all X2 column excitation groups and all Y2 row excitation groups are connected to form a B-phase excitation electrode group, all X3 column excitation groups and all Y3 row excitation groups are connected to form a C-phase excitation electrode group, and all X4 column excitation groups and all Y4 row excitation groups are connected to form a D-phase excitation electrode group.
3. The method for realizing XYZ displacement measurement on a planar grating sensor according to claim 1, wherein the displacement values X and Y in the X direction are obtained by the following method, The method comprises the steps of respectively carrying out phase comparison on U X and U Y through a shaping circuit after shaping Cheng Fangbo signals and an on-frequency reference square wave signal U R , carrying out interpolation counting on the phase difference by adopting a high-frequency pulse square wave signal U T , wherein the signal phase period corresponding to the period width W of one excitation electrode is 2 pi, the corresponding count value is c m , the high-frequency pulse square wave signal U T starts counting when recognizing the rising edge of the reference square wave signal U R , the output count value c t when recognizing the rising edge of the square wave signal U X , the output count value of a sensor at the t moment position is c t , the output count value at the t+1 moment position is c m corresponding to one period when c t+1 ,c t is full, and the corresponding displacement value is expressed as follows: , 。
4. The method for realizing XYZ displacement measurement on a planar grating sensor according to claim 1, wherein the proportional relationship between the digital signal and the displacement value in the Z direction is obtained by pre-calibrating in the following way, 1) The movable ruler substrate is arranged on a high-precision Z-direction displacement adjusting device, and the plane time grating sensor is in a normal working state; 2) Collecting a digital signal of a Z-direction displacement output signal U Z0 ,U Z0 subjected to synchronous demodulation, low-pass filtering and analog-digital conversion at an initial reference position as U 0 , and setting a Z-direction displacement value Z 0 =0 at the position; 3) Controlling the movable ruler substrate to move in a multi-point displacement manner along the Z direction according to a preset step length, and respectively collecting corresponding digital signals at each displacement position to obtain a plurality of groups of displacement values in the Z direction and corresponding data of the corresponding digital signals; 4) And establishing a functional mapping relation between the displacement value in the Z direction and the digital signal obtained by resolving the displacement output signal in the Z direction according to the plurality of groups of corresponding data, namely obtaining the proportional relation between the digital signal and the displacement value in the Z direction.
5. The method for realizing XYZ displacement measurement on a planar grating sensor according to claim 4, wherein the function mapping relationship is established by adopting a least square method for linear fitting, polynomial fitting, piecewise linear fitting or lookup table interpolation.
6. The method of claim 4, wherein the pre-calibration further comprises repeating the calibration process under different temperature conditions to build a temperature correction model for temperature compensation of the displacement value in the Z direction.
7. The method for measuring XYZ displacement on a planar grating sensor according to claim 1, wherein the displacement measurement signal U A 、U B 、U C 、U D output from the sensing electrode A, B, C, D is calculated as follows, Wherein A is the amplitude of the output signal, f s (x)、f c (x)、f s (y)、f c (y) is the phase function related to XY displacement in the output signal, f s (x)=cos(2πx/W),f c (x)=sin(2πx/W),f s (y)=cos(2πy/W),f c (y)=sin(2πy/W),W is the excitation electrode period width, U X =U A +U B -(U C +U D ), and further solving ; U Y =U A +U D -(U C +U B ) and further calculate to obtain 。

Description

Method for realizing XYZ displacement measurement on grid sensor in same plane Technical Field The invention relates to precise displacement measurement, in particular to a method for realizing XYZ displacement measurement on a grid sensor in the same plane, and belongs to the technical field of measurement and sensing. Background The precision displacement measurement technology is an important foundation in the industrial fields of large-scale integrated circuit manufacturing, precision machine tool machining, high-end equipment manufacturing and the like. Along with the continuous improvement of the requirements of ultra-precision machining and high-precision positioning, higher requirements are put on the measurement precision and multi-degree-of-freedom measurement of a displacement sensor in a positioning system. Therefore, the development of the multi-degree-of-freedom displacement measurement method with high precision, multiple dimensions and relatively simple structure has important engineering application value. At present, a relatively common three-degree-of-freedom displacement measurement method mainly comprises a grating and laser interferometer combined measurement method and a Hall sensor resolving method based on a magnetic field. The combined measurement mode of the grating and the laser interferometer can achieve higher measurement precision, but the combined measurement mode of the grating and the laser interferometer is subjected to multiple sensor combination type measurement, so that a light path contains spectral filtering interference, measurement output of multiple dimensions is inconsistent, and meanwhile, the laser interferometer is easily influenced by factors such as an ambient light source, temperature change and the like, and nonlinear errors are introduced. In addition, the combination of the two sensors makes the measurement system complex in structure, large in size and high in system construction and maintenance cost. The magnetic field type three-degree-of-freedom measuring method based on the Hall sensor has the advantages of high response speed, strong anti-interference capability and the like, but the measuring precision is limited by the magnetic field coil structure and the interference of an external environment magnetic field, and the requirement of high-precision displacement measurement is difficult to meet. The capacitive plane two-dimensional time grating displacement sensor (such as the technical scheme disclosed by the publication number CN 109631735A) has good application prospect in the fields of machine tool precision machining, workpiece table precision positioning measurement and the like because of the advantages of high precision, high resolution, non-contact measurement and the like. However, the current time grating displacement sensor can only realize measurement in two-dimensional directions, namely only can realize measurement in XY directions, and cannot realize measurement in XYZ directions at the same time. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide a method for realizing XYZ displacement measurement on a grid sensor in the same plane, and the invention realizes high-precision displacement measurement of a movable ruler in three directions X, Y, Z by carrying out cooperative detection and calculation on displacement signals of an XY plane and displacement signals of a Z direction, thereby greatly simplifying the system structure and improving the positioning precision, measurement dimension and engineering applicability of a measurement system. The technical scheme of the invention is realized as follows: The method for realizing XYZ displacement measurement on the grid sensor in the same plane comprises a movable ruler substrate and a fixed ruler substrate which are arranged in parallel up and down with a gap left, wherein a plurality of excitation electrodes with the same shape and size and the same interval are arranged on the upper surface of the fixed ruler substrate in a staggered manner along the X direction and the Y direction, a plurality of excitation groups formed by arranging the excitation electrodes in the X direction are correspondingly connected with a plurality of excitation groups formed by arranging the excitation electrodes in the Y direction, thereby forming A, B, C, D four-phase excitation electrode groups; When displacement measurement is carried out, sinusoidal excitation signals S+=A0sin(ωt)、C+=A0cos(ωt)、S-=-A0sin(ωt)、C-=-A0cos(ωt), with the same amplitude and frequency and phase difference pi/2 are sequentially applied to A, B, C, D four-phase excitation electrode groups, wherein A 0 is the amplitude of the applied excitation signals, and omega is the frequency of the applied excitation signals; When the movable ruler substrate moves on the XY plane, the sensing electrodes A, B, C, D respectively output displacement measurement signals U A、UB、UC、UD, obtain displaceme