An absolute planar two-dimensional time-grating displacement sensor and measurement method based on photoelectric combination measurement
By combining photoelectric measurement with electric and optical field measurements, absolute measurement of a two-dimensional planar time grating is achieved, solving the problems of large size and low accuracy in existing technologies, and making it suitable for high-precision, large-range measurements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING UNIV OF TECH
- Filing Date
- 2026-06-03
- Publication Date
- 2026-06-30
AI Technical Summary
Existing grating displacement sensors suffer from problems such as large size, difficulty in achieving large-range absolute positioning, and compromised measurement accuracy when performing absolute measurements.
The photoelectric combined measurement method is adopted. The precise measurement position is determined by electric field measurement and coarse measurement is performed by combining it with optical field measurement. This enables absolute measurement of a two-dimensional planar time grating. The optical measurement and electric field measurement are independent of each other and do not interfere with each other.
It improves measurement accuracy, reduces processing difficulty and system implementation cost, is suitable for mass production, and achieves a balance between large measurement range and high precision.
Smart Images
Figure CN122305897A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to an improvement in time-grating displacement measurement technology, specifically to an absolute planar two-dimensional time-grating displacement sensor and measurement method using photoelectric combination measurement, belonging to the field of precision measurement and sensing technology. Background Technology
[0002] High-precision and large-range linear displacement sensors are widely used in precision equipment, such as precision machine tools, military weapons, automobiles, medical devices, and high-precision worktables, serving as key functional units in these devices. Absolute sensors enable absolute displacement measurement, effectively solving the problem of data loss during power outages. They also allow for fully closed-loop control and feedback, reducing interference from external factors such as temperature, and improving sensor measurement accuracy, thus broadening their application range.
[0003] Currently, absolute measurement of grating displacement sensors is mainly achieved by using differential pole or coprime methods. Although absolute measurement is achieved, there are also drawbacks.
[0004] 1. When using differential or coprime positioning to achieve absolute positioning, two rows of sensors need to be set up. For example, two rows of excitation electrodes and two rows of sensing electrodes need to be set up on the fixed scale base and the moving scale base respectively, which increases the size of the sensor, especially the lateral width of the sensor, which is not conducive to compactness and miniaturization.
[0005] 2. When using a differential pole structure, the difficulty of achieving absolute positioning over a large range increases significantly, mainly due to positioning errors. Where l is the length of the sensor, and N and N-1 are the number of cycles of the two rows of sensors, respectively. As the range increases, the number of cycles required increases, the requirements for positioning error become higher, and the more difficult it is to achieve.
[0006] 3. When using differential or coprime sensors to achieve absolute positioning, there is mutual interference between the two rows of sensors, which will affect the measurement accuracy and is not conducive to high-precision, large-range measurement. Summary of the Invention
[0007] To address the aforementioned shortcomings of existing technologies, the purpose of this invention is to provide an absolute planar two-dimensional time-grating displacement sensor and measurement method using photoelectric combined measurement. This invention employs electric field measurement as a fine measurement and optical field measurement as a coarse measurement to determine the location of the fine measurement. The combination of the two can achieve absolute measurement of planar linear displacement, and the fine and coarse measurements do not interfere with each other, resulting in high measurement accuracy, simple structure, and ease of implementation.
[0008] The technical solution of this invention is implemented as follows:
[0009] An absolute planar two-dimensional time-grating displacement sensor for photoelectric combined measurement includes a sensor body, a signal acquisition module, a hardware circuit module, and a digital signal processing module. The sensor body includes a moving scale base and a fixed scale base arranged in parallel with a gap. The upper surface of the fixed scale base is arranged with 2K columns of excitation electrodes uniformly arranged along the X direction, where K = 4n, and n is a natural number greater than 1. All excitation electrodes are square with a side length of W. The number of excitation electrodes in each column is L, and L is a multiple of 4, with the multiple being greater than or equal to 2. The distance between adjacent excitation electrodes in each column is I, where I > W. All odd-numbered columns of excitation electrodes are aligned at their top and bottom ends, and all even-numbered columns are aligned at their top and bottom ends. The odd and even columns are staggered by a distance equal to I. The distance between two adjacent odd columns and two adjacent even columns is I.
[0010] In the K×L odd array of excitation electrodes composed of all odd-numbered columns of excitation electrodes, all excitation electrodes in each column are connected to form column excitation groups, thus forming K column excitation groups; starting from the first column, every four columns form a cycle, which are respectively called X1 column excitation group, X2 column excitation group, X3 column excitation group and X4 column excitation group;
[0011] In the K×L excitation electrode even array composed of all even-numbered excitation electrodes, all excitation electrodes in each row are connected to form row excitation groups, thus forming L rows of row excitation groups; starting from the first row, every four rows form a cycle, which are respectively called Y1 row excitation group, Y2 row excitation group, Y3 row excitation group and Y4 row excitation group;
[0012] The lower surface of the moving scale base is provided with four sensing electrodes arranged in a 2×2 matrix to form a sensing unit. Each sensing electrode is a square of the same size with a side length of g. The distance between two adjacent sensing electrodes is m; g+m=2(W+I). The sensing electrodes on the moving scale base are directly opposite the excitation electrodes on the fixed scale base.
[0013] The odd array and even array of excitation electrodes are respectively divided into multiple identical odd sub-arrays and even sub-arrays of excitation electrodes arranged in the same matrix e×f. Each odd sub-array of excitation electrodes and the corresponding even array of excitation electrodes form an excitation electrode group, resulting in an e×f arrangement of excitation electrode groups. Each excitation electrode is provided with encoded information, which consists of two markers. One marker is used to characterize the excitation electrode group to which the excitation electrode belongs, called the first marker, and the other marker is used to characterize the position of the excitation electrode in the odd sub-array or the even array of excitation electrodes, called the second marker. Two photosensitive sensors are arranged on the moving scale substrate at diagonal positions of the sensing unit. The width of the photosensitive sensors is W+I. The two photosensitive sensors are used to scan the encoded information on the excitation electrodes and output optical field signals when the moving scale substrate moves relative to the fixed scale substrate.
[0014] The signal acquisition module is used to acquire the electric field signal output by the sensing electrode and the light field signal output by the photosensitive sensor;
[0015] The hardware circuit module is used to amplify, shape, and filter the signal transmitted from the signal acquisition module and output it to the digital signal processing module.
[0016] The digital signal processing module is used to process the electric field signal and extract the displacement values in the X and Y directions; it also processes the optical field signal and extracts the position information of the moving scale substrate relative to the fixed scale substrate. The position information and displacement values are combined to output the absolute displacement values in the X and Y directions.
[0017] Preferably, n=2; K=L=8.
[0018] Preferably, the odd-numbered array and the even-numbered array of the excitation electrodes are i×j arrays and i = j = 4.
[0019] Preferably, the surface of each excitation electrode is divided into multiple regions arranged in an a×b matrix, where a≥i and b≥j; the first mark is set at the corresponding coordinate position in the region according to the coordinate position of the excitation electrode group to which the excitation electrode belongs in all excitation electrode groups; the second mark is set at the corresponding coordinate position in the region according to the coordinate position of the excitation electrode in the odd or even array of excitation electrodes in the corresponding excitation electrode group; if the coordinate positions of the first mark and the second mark are the same, then they share a common coordinate position.
[0020] Preferably, both markings are black light-absorbing patterns, and the rest of the excitation electrode surface, except for the markings, is a white reflective pattern.
[0021] This invention also provides an absolute planar two-dimensional time-grating displacement measurement method using photoelectric combination measurement, wherein the aforementioned absolute planar two-dimensional time-grating displacement sensor using photoelectric combination measurement is obtained in advance; the measurement steps are as follows:
[0022] 1) First, power on the sensor. The two photosensitive sensors on the moving scale substrate scan the encoding information of the excitation electrodes on the fixed scale substrate and generate corresponding light field signals. The excitation electrode group where the center of the moving scale substrate is located is determined by the two light field signals, and the initial position of the moving scale substrate when powered on is obtained.
[0023] 2) Then disconnect the power supply of the photosensitive sensor. While keeping the moving scale base stationary, sequentially apply four equal-amplitude and same-frequency sinusoidal excitation signals with a 90° phase difference to the X1-X4 columns of the excitation electrode odd array, and sequentially apply four equal-amplitude and same-frequency sinusoidal excitation signals with a 90° phase difference to the Y1-Y4 rows of the excitation electrode even array. The four sensing electrodes generate four sensing signals in the X and Y directions respectively. The initial values of the X-direction precision measurement x0 and Y-direction precision measurement y0 are obtained by solving the sensing signals.
[0024] 3) Based on the initial position of the moving scale base obtained in step 1) when powered on and the initial values of X-direction precision measurement x0 and Y-direction precision measurement y0 obtained in step 2), determine the initial absolute position of the moving scale base in the X-direction and the initial absolute position in the Y-direction.
[0025] 4) While maintaining the application of the X-direction sinusoidal excitation signal and the Y-direction sinusoidal excitation signal, when the moving scale base moves parallel to the fixed scale base, the four induction electrodes generate four induction signals in the X and Y directions respectively. The precise displacement values in the X and Y directions are obtained by solving the induction signals.
[0026] 5) Based on the initial absolute position in the X direction and the initial absolute position in the Y direction obtained in step 3), and by summing the precise displacement values in the X direction and the precise displacement values in the Y direction obtained in step 4), the absolute displacement value x in the X direction and the absolute displacement value y in the Y direction are obtained, thus realizing the absolute displacement measurement.
[0027] Furthermore, the excitation electrode groups arranged in an e×f pattern are placed in the first quadrant of the XOY plane coordinate system. For each excitation electrode group, its coordinates are defined according to its column in the X direction and its row in the Y direction. The coordinates (p, q) of the excitation electrode group corresponding to the initial position of the moving scale base when powered on indicate that the excitation electrode group is located in the p-th column and q-th row. The coordinates (p, q) represent the initial position of the moving scale base when powered on. Then, the initial absolute position x of the moving scale base in the X direction is... 初绝 and the initial absolute position y in the Y direction 初绝 Represented as,
[0028] x 初绝 = S×(p - 1) + x0; y 初绝 = S×(q -1)+y0;
[0029] In the formula, S is the length of a single excitation electrode group.
[0030] Compared with the prior art, the present invention has the following beneficial effects:
[0031] This invention employs a photoelectric combined measurement method, utilizing time-division image positioning and electric field displacement measurement. Optical field measurement serves as the coarse measure to determine the precise measurement location, while electric field displacement measurement serves as the fine measure. The combination of these two methods enables absolute measurement of a two-dimensional planar time grating. Absolute positioning measurement is achieved simply by adding a photoelectric coding structure with group and intra-group coding on the electrode plate, based on the original electric field displacement measurement sensor. Furthermore, optical and electric field measurements operate independently without interference, reducing random errors and improving measurement accuracy, achieving a balance between a large measurement range and high precision. Secondly, compared to some complex coding methods, this optical coding method has advantages in terms of algorithm complexity, processing accuracy requirements, and system cost. Its coding method is simple, with a regular graphic structure, lower requirements for processing resolution and alignment accuracy, making it easy to implement using conventional processes and suitable for mass production. It can reduce processing difficulty and system implementation costs while ensuring measurement performance, and also reduces the demand for processor computing power and storage resources.
[0032] In this invention, the initial absolute position of the moving scale is determined only when the power is first applied. Once the initial absolute position of the moving scale is determined, the optical field power supply can be turned off. Subsequently, when an excitation signal is applied, as the moving scale moves relative to the stationary scale, the electric field achieves precise measurement of the relative displacement. This precise measurement value is continuously accumulated at the initial absolute position, thus achieving absolute displacement measurement. Attached Figure Description
[0033] Figure 1 This is a schematic diagram of the fixed-length base structure of the present invention.
[0034] Figure 2 This is a schematic diagram of the moving ruler base structure of the present invention.
[0035] Figure 3 This is a schematic diagram of the measurement process of the fixed-length base and the moving-length base of the present invention.
[0036] Figure 4 This is a flowchart of the measurement method of the present invention.
[0037] Note: Figure 1 and Figure 3 The XYZ coordinate system in the diagram represents the same coordinate system, with X, Y, and Z representing three mutually perpendicular directions in space, namely the X, Y, and Z directions. Detailed Implementation
[0038] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.
[0039] This invention discloses an absolute planar two-dimensional time-grating displacement sensor for photoelectric combined measurement, comprising a sensor body, a signal acquisition module, a hardware circuit module, and a digital signal processing module. For example... Figures 1-3As shown, the sensor body includes a moving scale base and a fixed scale base arranged in parallel with a gap between them. The upper surface of the fixed scale base has 2K columns of excitation electrodes uniformly arranged along the X direction, where K = 4n, and n is a natural number greater than 1. All excitation electrodes are square with a side length of W; the number of excitation electrodes in each column is L, and L is a multiple of 4, with the multiple being greater than or equal to 2. The distance between adjacent excitation electrodes in each column is I, where I > W. All odd-numbered columns of excitation electrodes are aligned at their top and bottom ends, and all even-numbered columns are aligned at their top and bottom ends. The odd and even columns are staggered by a distance of I; the distance between two adjacent odd columns and two adjacent even columns is I.
[0040] In the K×L odd array of excitation electrodes composed of all odd-numbered columns of excitation electrodes, all excitation electrodes in each column are connected to form column excitation groups, thus forming K column excitation groups; starting from the first column, every four columns form a cycle, which are respectively called the X1 column excitation group, X2 column excitation group, X3 column excitation group and X4 column excitation group.
[0041] In the K×L excitation electrode pair array composed of all even-numbered excitation electrodes, all excitation electrodes in each row are connected to form row excitation groups, thus forming L rows of row excitation groups; starting from the first row, every four rows form a cycle, which are respectively called Y1 row excitation group, Y2 row excitation group, Y3 row excitation group and Y4 row excitation group.
[0042] See Figure 2 The lower surface of the moving scale base is provided with four sensing electrodes 1-1 arranged in a 2×2 matrix to form a sensing unit. Each sensing electrode 1-1 is a square of the same size with a side length of g. The distance between two adjacent sensing electrodes is m; g+m=2(W+I). The sensing electrodes on the moving scale base are directly opposite the excitation electrodes on the fixed scale base.
[0043] The electric field measurement scheme composed of the excitation electrode and the induction electrode described above can only achieve precise measurement of the relative displacement of the moving scale, which is called fine measurement. Although the relative displacement measurement accuracy is relatively high, it cannot achieve absolute displacement measurement. To achieve absolute displacement measurement, existing technologies usually design a coarse measurement scheme. The coarse measurement is used to determine the period in which the fine measurement is performed, and the combination of fine measurement and coarse measurement achieves absolute displacement measurement. This invention proposes a coarse measurement scheme that is completely different from the existing technology. Without changing the original electric field structure of the sensor, this invention only needs to perform optical encoding on the excitation electrode plate of the sensor, and perform coarse positioning through optical measurement. Compared with the original differential positioning or coprime method, it can effectively reduce crosstalk between coarse and fine levels. Moreover, the optical encoding method of this invention is simpler than the existing encoding methods, with a regular graphic structure, lower requirements for processing resolution and alignment accuracy, and is easy to implement using conventional processes. It has certain advantages in terms of algorithm complexity, processing accuracy requirements, and system cost. See below for details. Figure 1The excitation electrode odd array and excitation electrode even array are respectively divided into multiple identical excitation electrode odd sub-arrays and excitation electrode even arrays arranged with the same matrix e×f. Each excitation electrode odd sub-array and the corresponding excitation electrode even array form an excitation electrode group, resulting in an e×f arranged excitation electrode group. To determine the position of the moving scale, the present invention provides coded information on each excitation electrode. The coded information consists of two marks. One mark is used to characterize the excitation electrode group to which the excitation electrode belongs, called the first mark. The other mark is used to characterize the position of the excitation electrode in the excitation electrode odd sub-array or excitation electrode even array, called the second mark. Two photosensitive sensors 1-2 are arranged on the moving scale substrate at diagonal positions of the sensing unit. The width of the photosensitive sensors 1-2 is W+I. The two photosensitive sensors are used to scan the coded information on the excitation electrodes and output optical field signals when the moving scale substrate moves relative to the fixed scale substrate. Different coding information represents the location of each excitation electrode. The different coding information scanned by the photosensitive sensor on the moving scale substrate indicates the different positions that the moving scale substrate has moved to. Combining the precise measurement value with the positioning information yields the absolute displacement value.
[0044] In this embodiment, W + I = 2.5mm, and the gap d between the moving scale base and the fixed scale base is 2mm.
[0045] The signal acquisition module is used to acquire the electric field signal output by the sensing electrode and the light field signal output by the photosensitive sensor.
[0046] The hardware circuit module is used to amplify, shape, and filter the signals transmitted from the signal acquisition module and output them to the digital signal processing module.
[0047] The digital signal processing module processes the electric field signal to extract the X-direction and Y-direction displacement values, thus obtaining the precise measurement values. Simultaneously, it processes the optical field signal to extract the position information of the moving scale base relative to the fixed scale base. Combining this position information with the precise displacement values outputs the absolute displacement values in the X and Y directions.
[0048] As an example, such as Figure 1 As shown, n=2; K=L=8; that is, there are a total of 16 columns of excitation electrodes, 8 columns of odd-numbered columns and 8 columns of even-numbered columns; the number of excitation electrodes in each column is 8; the odd array of excitation electrodes composed of all odd-numbered columns is an 8×8 array; similarly, the even array of excitation electrodes is also an 8×8 array.
[0049] The odd-numbered array and even-numbered array of the excitation electrodes are i×j arrays (4×4 in the embodiment shown in the figure). Therefore, each excitation electrode group in this embodiment has 32 excitation electrodes, and there are a total of 4 excitation electrode groups.
[0050] As one implementation method, the specific coding rules of this invention are as follows: each excitation electrode surface is divided into a×b ( Figure 1 The above embodiment uses a 4×4 matrix arrangement of multiple regions, where a≥i and b≥j. The first mark is set at the corresponding coordinate position in the region according to the coordinate position of the excitation electrode group within all excitation electrode groups; for example, if the coordinate position of the excitation electrode group is (1, 2), it indicates that the excitation electrode group is located in the first column and second row among all excitation electrode groups, and the region corresponding to the first column and second row in the excitation electrode division region is marked. The second mark is set at the corresponding coordinate position in the region according to the coordinate position of the excitation electrode in the corresponding odd-numbered array or even-numbered array of excitation electrodes; the principle is the same as the first mark.
[0051] Therefore, according to the coding rules of this invention, the first mark position is the same for all excitation electrodes in the same excitation electrode group, while the second mark positions are all different. However, the marks of all excitation electrodes in the odd-numbered array and the marks of all excitation electrodes in the even-numbered array correspond to the same value. Because of this, this invention uses two photosensitive sensors, which, when combined, can determine the center position of the moving scale substrate. This invention only requires locating the moving scale substrate to a certain excitation electrode group, rather than to a specific excitation electrode, which reduces measurement requirements and makes it easier to implement.
[0052] According to the above coding rules, it is possible that the first and second markers are located at the same coordinate position. In this case, they share the same coordinate position, that is, they share the same marker. In other words, if there is only one sensing marker on the excitation electrode, it means that both the first and second markers are at that position.
[0053] In this embodiment, both markers are black light-absorbing patterns; simply coloring the corresponding areas black is sufficient. Apart from the markers, the remaining surface of the excitation electrode is a white reflective pattern. The photosensitive sensor consists of a light source and a receiver. Light emitted from the light source illuminates the excitation electrode. Because the black patterns absorb the light, reflected light is generated outside the markers. Therefore, different excitation electrodes will reflect different amounts of light, which is then received by the receiver. The different reflected light due to different encodings results in different optical field signals output by the receiver. By subsequently processing and analyzing these optical field signals, the position of the excitation electrode group can be determined.
[0054] The displacement measurement steps for the absolute planar two-dimensional time-grating displacement sensor described above, which can be found in the following references: Figure 4 ,
[0055] 1) First, power on the sensor. The two photosensitive sensors on the moving scale base scan the encoded information of the excitation electrodes on the fixed scale base and generate corresponding light field signals. The relevant image positioning signals are obtained through the light field information and input to the hardware circuit module. The hardware circuit module amplifies and filters the image signals and outputs them to the digital signal processing module. Then, through image analysis and decoupling analysis of multiple photosensitive probes, the excitation electrode group where the center of the moving scale base is located is determined, and the initial positioning position information of the moving scale base when powered on is obtained.
[0056] 2) Then, disconnect the power supply to the photosensitive sensor. While keeping the moving scale base stationary, sequentially apply four equal-amplitude, same-frequency X-axis sinusoidal excitation signals (90° phase difference) to the X1-X4 columns of the odd array of excitation electrodes via the excitation circuit. Similarly, sequentially apply four equal-amplitude, same-frequency Y-axis sinusoidal excitation signals (90° phase difference) to the Y1-Y4 rows of the even array of excitation electrodes. The four X-axis and four Y-axis sinusoidal excitation signals are applied simultaneously. Since they are all sinusoidal excitation signals, their expressions are the same. The four sinusoidal excitation signals are shown below:
[0057]
[0058] In the formula, For AC signal amplitude, Angular frequency, For time.
[0059] Four sensing electrodes generate four sensing signals in the X and Y directions respectively. The signal acquisition module collects and processes each of the four sensing signals in the X and Y directions and inputs them to the hardware circuit module. The hardware circuit module amplifies, shapes, and filters the signals and outputs them to the digital signal processing module. Then, the displacement analysis of the signals is performed using time interpolation technology to finally obtain the initial value x0 in the X direction and the initial value y0 in the Y direction.
[0060] 3) Based on the initial positioning position of the moving scale base obtained in step 1) when powered on and the initial precision measurement values x0 and y0 in the X and Y directions obtained in step 2), determine the initial absolute position of the moving scale base in the X and Y directions.
[0061] 4) While maintaining the application of the X-direction sinusoidal excitation signal and the Y-direction sinusoidal excitation signal, when the moving scale base moves parallel to the fixed scale base, the four induction electrodes generate four induction signals in the X and Y directions respectively. The precise displacement values in the X and Y directions are obtained by solving the induction signals.
[0062] 5) Inside the digital signal processing module, based on the initial absolute position in the X direction and the initial absolute position in the Y direction obtained in step 3), and by summing the precise displacement values in the X direction and the precise displacement values in the Y direction obtained in step 4), the absolute displacement values in the X direction x and Y direction y are obtained and output to the host computer to realize the absolute displacement measurement.
[0063] Step 3) The initial absolute positions in the X and Y directions can be determined as follows: Place the excitation electrode groups arranged in an e×f pattern in the first quadrant of the XOY plane coordinate system. For each excitation electrode group, define its coordinates according to its column in the X direction and its row in the Y direction. The coordinates (p, q) of the excitation electrode group corresponding to the initial position of the moving scale base when powered on indicate that the excitation electrode group is located in the p-th column and q-th row. The coordinates (p, q) represent the initial position of the moving scale base when powered on. Therefore, the initial absolute position x of the moving scale base in the X direction is... 初绝 and the initial absolute position y in the Y direction 初绝 Represented as,
[0064] x 初绝 = S×(p - 1) + x0; y 初绝 = S×(q -1)+y0;
[0065] In the formula, S is the length of a single excitation electrode group.
[0066] This invention employs a photoelectric combined measurement method, utilizing time-division image positioning and electric field displacement measurement. Optical field measurement serves as the coarse measurement to determine the precise measurement location, while electric field displacement measurement serves as the fine measurement. The combination of these two methods enables absolute measurement of a two-dimensional planar time grating. This invention achieves absolute positioning measurement simply by adding a photoelectric coding structure with group coding and intra-group coding on the electrode plate, based on the original electric field displacement measurement sensor. Optical and electric field measurements operate independently without interference, reducing random errors and improving measurement accuracy, achieving a balance between a large measurement range and high precision. Compared to some complex coding methods, the optical coding method of this invention has advantages in terms of algorithm complexity, processing accuracy requirements, and system cost. Its coding method is simple, with a regular graphic structure, lower requirements for processing resolution and alignment accuracy, and is easy to implement using conventional processes. It is suitable for mass production, reducing processing difficulty and system implementation costs while ensuring measurement performance, and minimizing the demand for processor computing power and storage resources.
[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the applicant has described the present invention in detail with reference to preferred embodiments, those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.
Claims
1. An absolute planar two-dimensional time-grating displacement sensor for photoelectric combined measurement, comprising a sensor body, a signal acquisition module, a hardware circuit module, and a digital signal processing module; the sensor body comprises a moving scale base and a fixed scale base arranged in parallel with a gap, wherein the upper surface of the fixed scale base is provided with 2K columns of excitation electrodes uniformly arranged along the X direction, where K=4n, and n is a natural number greater than 1; all excitation electrodes are square with a side length of W; the number of excitation electrodes in each column is L, and L is a multiple of 4, and the multiple is greater than or equal to 2; the spacing between adjacent excitation electrodes in each column is I, where I>W; all odd-numbered columns of excitation electrodes are aligned at their top and bottom ends, all even-numbered columns of excitation electrodes are aligned at their top and bottom ends, and the odd and even columns are staggered by a distance equal to I; the spacing between two adjacent odd columns and two adjacent even columns is I; In the K×L odd array of excitation electrodes composed of all odd-numbered columns of excitation electrodes, all excitation electrodes in each column are connected to form column excitation groups, thus forming K column excitation groups; starting from the first column, every four columns form a cycle, which are respectively called X1 column excitation group, X2 column excitation group, X3 column excitation group and X4 column excitation group; In the K×L excitation electrode even array composed of all even-numbered excitation electrodes, all excitation electrodes in each row are connected to form row excitation groups, thus forming L rows of row excitation groups; starting from the first row, every four rows form a cycle, which are respectively called Y1 row excitation group, Y2 row excitation group, Y3 row excitation group and Y4 row excitation group; The lower surface of the movable scale base is provided with four sensing electrodes arranged in a 2×2 matrix to form a sensing unit. Each sensing electrode is a square of the same size with a side length of g, and the distance between any two adjacent sensing electrodes is m; g+m=2(W+I). The sensing electrodes on the movable scale base are directly opposite the excitation electrodes on the fixed scale base. Its characteristic is that: The odd array and even array of excitation electrodes are respectively divided into multiple identical odd sub-arrays and even sub-arrays of excitation electrodes arranged in the same matrix e×f. Each odd sub-array of excitation electrodes and the corresponding even array of excitation electrodes form an excitation electrode group, resulting in an e×f arrangement of excitation electrode groups. Each excitation electrode is provided with encoded information, which consists of two markers. One marker is used to characterize the excitation electrode group to which the excitation electrode belongs, called the first marker, and the other marker is used to characterize the position of the excitation electrode in the odd sub-array or the even array of excitation electrodes, called the second marker. Two photosensitive sensors are arranged on the moving scale substrate at diagonal positions of the sensing unit. The width of the photosensitive sensors is W+I. The two photosensitive sensors are used to scan the encoded information on the excitation electrodes and output optical field signals when the moving scale substrate moves relative to the fixed scale substrate. The signal acquisition module is used to acquire the electric field signal output by the sensing electrode and the light field signal output by the photosensitive sensor; The hardware circuit module is used to amplify, shape, and filter the signal transmitted from the signal acquisition module and output it to the digital signal processing module. The digital signal processing module is used to process the electric field signal and extract the displacement values in the X and Y directions; it also processes the optical field signal and extracts the position information of the moving scale substrate relative to the fixed scale substrate. The position information and displacement values are combined to output the absolute displacement values in the X and Y directions.
2. The absolute planar two-dimensional time-grating displacement sensor for photoelectric combined measurement according to claim 1, characterized in that: The values are n=2; K=L=8.
3. The absolute planar two-dimensional time-grating displacement sensor for photoelectric combined measurement according to claim 1, characterized in that: The odd-numbered array and even-numbered array of the excitation electrodes are i×j arrays and i = j = 4.
4. The absolute planar two-dimensional time-grating displacement sensor for photoelectric combined measurement according to claim 3, characterized in that: Each excitation electrode surface is divided into multiple regions arranged in an a×b matrix, where a≥i and b≥j. The first mark is set at the corresponding coordinate position in the region according to the coordinate position of the excitation electrode group to which the excitation electrode belongs in all excitation electrode groups. The second mark is set at the corresponding coordinate position in the region according to the coordinate position of the excitation electrode in the odd or even array of excitation electrodes in the corresponding excitation electrode group. If the first mark and the second mark are at the same coordinate position, they share the same coordinate position.
5. The absolute planar two-dimensional time-grating displacement sensor for photoelectric combined measurement according to claim 1, characterized in that: Both markings are black light-absorbing patterns, while the rest of the excitation electrode surface, apart from the markings, is a white reflective pattern.
6. A method for absolute planar two-dimensional time-grating displacement measurement using photoelectric combination measurement, characterized in that: The following steps are taken to obtain an absolute planar two-dimensional time-grating displacement sensor for photoelectric combined measurement as described in any one of claims 1-5: 1) First, power on the sensor. The two photosensitive sensors on the moving scale substrate scan the encoding information of the excitation electrodes on the fixed scale substrate and generate corresponding light field signals. The excitation electrode group where the center of the moving scale substrate is located is determined by the two light field signals, and the initial position of the moving scale substrate when powered on is obtained. 2) Then disconnect the power supply of the photosensitive sensor. While keeping the moving scale base stationary, sequentially apply four equal-amplitude and same-frequency sinusoidal excitation signals with a 90° phase difference to the X1-X4 columns of the excitation electrode odd array, and sequentially apply four equal-amplitude and same-frequency sinusoidal excitation signals with a 90° phase difference to the Y1-Y4 rows of the excitation electrode even array. The four sensing electrodes generate four sensing signals in the X and Y directions respectively. The initial values of the X-direction precision measurement x0 and Y-direction precision measurement y0 are obtained by solving the sensing signals. 3) Based on the initial position of the moving scale base obtained in step 1) when powered on and the initial values of X-direction precision measurement x0 and Y-direction precision measurement y0 obtained in step 2), determine the initial absolute position of the moving scale base in the X-direction and the initial absolute position in the Y-direction. 4) While maintaining the application of the X-direction sinusoidal excitation signal and the Y-direction sinusoidal excitation signal, when the moving scale base moves parallel to the fixed scale base, the four induction electrodes generate four induction signals in the X and Y directions respectively. The precise displacement values in the X and Y directions are obtained by solving the induction signals. 5) Based on the initial absolute position in the X direction and the initial absolute position in the Y direction obtained in step 3), and by summing the precise displacement values in the X direction and the precise displacement values in the Y direction obtained in step 4), the absolute displacement value x in the X direction and the absolute displacement value y in the Y direction are obtained, thus realizing the absolute displacement measurement.
7. The absolute planar two-dimensional time grating displacement measurement method of photoelectric combined measurement according to claim 6, characterized in that: The excitation electrode groups arranged in an e×f pattern are placed in the first quadrant of the XOY plane coordinate system. For each excitation electrode group, its coordinates are defined according to its column in the X direction and its row in the Y direction. The coordinates (p, q) of the excitation electrode group corresponding to the initial position of the moving scale base when powered on indicate that the excitation electrode group is located in the p-th column and q-th row. The coordinates (p, q) represent the initial position of the moving scale base when powered on. Then the initial absolute position x of the moving scale base in the X direction is... 初绝 and the initial absolute position y in the Y direction 初绝 Represented as, x 初绝 = S×(p -1)+x0;y 初绝 = S×(q -1)+y0; In the formula, S is the length of a single excitation electrode group.