Absolute type planar two-dimensional time grating displacement sensor based on alternating electric field and measuring method

Abstract

The invention discloses an absolute type planar two-dimensional time grating displacement sensor based on an alternating electric field and a measuring method. Excitation signals are applied to X excitation pairs in sequence, when an induction electrode generates an induction signal, the excitation signals are stopped from being applied to the remaining X excitation pairs, and four paths of electric signals generated by an induction group are processed, so that the absolute type planar two-dimensional time grating displacement sensor based on the alternating electric field is obtained. Obtaining the X excitation antipode of the movable ruler base body and the displacement position of the movable ruler base body in the X excitation antipode so as to obtain the two-dimensional time grating absolute displacement value of the movable ruler base body relative to the fixed ruler base body in the X direction; similarly, a two-dimensional time grating absolute displacement value of the movable ruler base body in the Y direction is obtained; and then taking the two-dimensional time grating absolute displacement values in the XY direction as the coordinates of the movable ruler base body in the XY direction to obtain the absolute displacement of the movable ruler base body. The absolute positions in the X direction and the Y direction are obtained in a scanning mode so as to achieve planar two-dimensional absolute displacement measurement, accumulated errors and random errors can be reduced, the measurement precision can be improved, and wide-range high-precision measurement can be achieved.

Description

Technical Field

[0001] The present invention relates to an improvement in linear displacement sensor measurement technology, and more particularly to an absolute planar two-dimensional time grating displacement sensor and a measurement method based on an alternating electric field, belonging to the field of planar two-dimensional displacement precision measurement sensing technology. Background Art

[0002] Precision displacement measurement technology is widely used in various precision motion control fields such as numerical control machine tools, chip manufacturing, metrology and testing, aerospace, and national defense industries. Existing planar two-dimensional displacement sensors can be mainly divided into three types: optical, capacitive, and inductive. Among them, the optical planar two-dimensional displacement sensor is relatively mature, but it overly relies on ultra-precision scribing technology and has weak resistance to oil contamination and shock vibration; the capacitive planar two-dimensional time grating sensor consists of a fixed scale and a moving scale. The dielectric constant of the capacitive planar two-dimensional displacement sensor is easily affected by external environments such as temperature, and its anti-interference ability is weak. Currently, the developed planar two-dimensional time grating displacement sensors are mainly incremental type, which has disadvantages such as cumulative error, manual zeroing required after power-on, and data loss after power-off.

[0003] The applicant applied for a patent for invention named "A Self-Calibration Method Based on a Planar Two-Dimensional Time Grating Sensor" on November 22, 2024. In it, the excitation electrodes are arranged in 2m rows side by side on the upper surface of the fixed scale substrate. Each row of excitation electrodes is composed of the same n square excitation electrode pieces evenly arranged along the X-axis direction. The starting positions of adjacent two rows of excitation electrodes are staggered by a certain distance along the X-axis direction; the starting positions of the odd rows of excitation electrodes are the same along the X-axis direction, and the starting positions of the even rows of excitation electrodes are the same along the X-axis direction; n = 4k1, m = 4k2;

[0004] In the excitation electrode array composed of all odd rows of excitation electrodes, all the excitation electrodes in each row are respectively connected to form a row excitation group, thus forming m 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;

[0005] In the excitation electrode array composed of all even rows of excitation electrodes, all the excitation electrodes in each column are respectively connected to form a column excitation group, thus forming m 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;

[0006] All the X1 column excitation groups are connected to all the Y1 row excitation groups to form the A-phase excitation electrode group; all the X2 column excitation groups are connected to all the Y2 row excitation groups to form the B-phase excitation electrode group; all the X3 column excitation groups are connected to all the Y3 row excitation groups to form the C-phase excitation electrode group; all the X4 column excitation groups are connected to all the Y4 row excitation groups to form the D-phase excitation electrode group. During operation, sinusoidal excitation voltages with the same amplitude and frequency and a phase difference of π / 2 are sequentially applied to the A, B, C, and D-phase excitation electrode groups; by correspondingly processing the output of the induction electrodes, self-calibration and displacement measurement can be achieved.

[0007] The above-mentioned sensor is an incremental type, and it also has disadvantages such as cumulative error, the need for manual zeroing after power-on, and data loss after power-off, so self-calibration is required. Summary of the Invention

[0008] Aiming at the above-mentioned deficiencies in existing displacement measurement, the purpose of the present invention is to provide an absolute planar two-dimensional time grating displacement sensor and a measurement method based on an alternating electric field. The structure of the present invention is simple. By separately obtaining the absolute positions in the x-direction and y-direction, the measurement of planar two-dimensional absolute displacement can be realized, which can reduce cumulative error and random error, improve measurement accuracy, and can achieve high-precision measurement with a large measurement range.

[0009] The technical solution of the present invention is realized as follows:

[0010] An absolute planar two-dimensional time grating displacement sensor based on an alternating electric field, including a fixed scale base body and a moving scale base body. The lower surface of the moving scale base body is installed parallel and facing the upper surface of the fixed scale base body with a gap left; on the upper surface of the fixed scale base body, 2m rows of excitation electrodes are arranged side by side. Each row of excitation electrodes is composed of the same n square excitation pole pieces evenly arranged along the X-axis direction. The distance Ie between adjacent two square excitation pole pieces is greater than the width Le of a square excitation pole piece. The distance between adjacent two rows of excitation electrodes along the Y-axis direction is (Ie - Le) / 2, and the starting position along the X-axis direction is staggered by (Ie + Le) / 2: the starting positions of odd rows of excitation electrodes along the X-axis direction are the same, and the starting positions of even rows of excitation electrodes along the X-axis direction are the same; where n = 4k1, m = 4k2, and k1 and k2 are both positive integers;

[0011] The lower surface of the moving scale base body is provided with induction electrodes, and the induction electrodes on the moving scale base body are directly opposite to the excitation electrodes on the fixed scale base body; the induction electrodes are composed of r induction units arranged in a matrix, and the distance between two adjacent induction units is Ii; each induction unit is composed of 4 identical square induction electrodes a, b, c, and d arranged in a 2x2 manner. The side length of each induction electrode is Li, and the distance between two adjacent induction electrodes is Ii. Li + Ii = 2(Le + Ie); the induction electrodes a in all induction units are connected together to form an a induction group, the induction electrodes b in all induction units are connected together to form a b induction group, the induction electrodes c in all induction units are connected together to form a c induction group, and the induction electrodes d in all induction units are connected together to form a d induction group;

[0012] In the excitation electrode array composed of excitation electrodes in all odd rows, all the excitation electrodes in each row are respectively connected together to form a Y excitation unit, and thus m Y excitation units are formed; starting from the first one, every four Y excitation units successively form a Y excitation pair stage, and there are a total of k2 Y excitation pair stages; the four Y excitation units in each Y excitation pair stage are successively called a YA excitation unit, a YB excitation unit, a YC excitation unit, and a YD excitation unit;

[0013] In the excitation electrode array composed of excitation electrodes in all even rows, all the excitation electrodes in each column are respectively connected together to form an X excitation unit, and thus n X excitation units are formed; starting from the first one, every four X excitation units successively form an X excitation pair stage, and there are a total of k1 X excitation pair stages; the four X excitation units in each X excitation pair stage are successively called an XA excitation unit, an XB excitation unit, an XC excitation unit, and an XD excitation unit;

[0014] It further includes a drive circuit, and the drive circuit is used to sequentially drive k1 X excitation pair stages and k2 Y excitation pair stages to generate excitation signals; when driving each X excitation pair stage, sinusoidal excitation signals with the same amplitude and frequency and phases successively differing by π / 2 are respectively applied to the XA excitation unit, the XB excitation unit, the XC excitation unit, and the XD excitation unit; when driving each Y excitation pair stage, sinusoidal excitation signals with the same amplitude and frequency and phases successively differing by π / 2 are respectively applied to the YA excitation unit, the YB excitation unit, the YC excitation unit, and the YD excitation unit; when electric field coupling occurs between the moving scale base body and the fixed scale base body, the a, b, c, and d induction groups respectively generate four-way induction signals for the X excitation pair stage and the Y excitation pair stage, and after being respectively processed, the linear displacement of the moving scale base body relative to the fixed scale base body in the X-axis direction and the linear displacement in the Y-axis direction are obtained.

[0015] Let the width of the induction unit be W, and it satisfies W = 2(Li + Ii) = 4(Le + Ie).

[0016] The present invention also provides an absolute planar two-dimensional time grating displacement measurement method based on an alternating electric field, which is realized by using the aforementioned absolute planar two-dimensional time grating displacement sensor based on an alternating electric field; during measurement,

[0017] An excitation signal is sequentially applied to k1 X excitation pair stages. When the induction electrodes on the moving scale base generate induction signals due to electric field coupling, the application of the excitation signal to the remaining X excitation pair stages is stopped. By processing the four-channel electrical signals generated by the a, b, c, and d induction groups, it is obtained which X excitation pair pole the moving scale base is located in and the displacement position within the X excitation pair pole, thereby obtaining the absolute displacement value of the moving scale base relative to the fixed scale base in the X direction of the two-dimensional time grating;

[0018] An excitation signal is sequentially applied to k2 Y excitation pair stages. When the induction electrodes on the moving scale base generate induction signals due to electric field coupling, the application of the excitation signal to the remaining Y excitation pair stages is stopped. By processing the four-channel electrical signals generated by the a, b, c, and d induction groups, it is obtained which Y excitation pair pole the moving scale base is located in and the displacement position within the Y excitation pair pole, thereby obtaining the absolute displacement value of the moving scale base relative to the fixed scale base in the Y direction of the two-dimensional time grating;

[0019] Then, the absolute displacement value of the two-dimensional time grating in the X direction and the absolute displacement value of the two-dimensional time grating in the Y direction are used as the coordinates of the moving scale base in the X direction and the Y direction, that is, the absolute displacement of the moving scale base is obtained.

[0020] Further, if the excitation signal is applied to the X excitation pair stages from left to right, the induction signals of the induction group composed of the induction pole pieces corresponding to the left column where each induction unit is located are taken for resolution processing; if the excitation signal is applied to the X excitation pair stages from right to left, the induction signals of the induction group composed of the induction pole pieces corresponding to the right column where each induction unit is located are taken for resolution processing;

[0021] If the excitation signal is applied to the Y excitation pair stages from top to bottom, the induction signals of the induction group composed of the induction pole pieces in the upper row of each induction unit are taken for resolution processing; if the excitation signal is applied to the Y excitation pair stages from bottom to top, the induction signals of the induction group composed of the induction pole pieces in the lower row corresponding to each induction unit are taken for resolution processing.

[0022] The present invention can apply the excitation signal to the k1 X excitation pair stages and the k2 Y excitation pair stages simultaneously; or the excitation signal can be applied to the k1 X excitation pair stages and the k2 Y excitation pair stages separately.

[0023] Through software control, the present invention sequentially applies excitation signals (sin+, cos+, sin-, cos-) to the excitation pole pieces of the scale base along the X direction and the Y direction: along the X direction, the excitation signals are sequentially applied from the counter electrode X1 to the counter electrode Xn; along the Y direction, the excitation signals are sequentially applied from the counter electrode Y1 to the counter electrode Yn. When scanning the Mth path in the X direction, if the induction pole piece on the moving scale base is electrically coupled with the excitation pole piece on the fixed scale base to generate an induction signal and feedback it to the host computer, the position of the moving scale base within which counter electrode and the displacement position within the counter electrode can be obtained, and thus the absolute displacement value of the two-dimensional time grating in the X direction can be obtained; similarly, when scanning the Nth path in the Y direction, if the induction pole piece on the moving scale base is electrically coupled with the excitation pole piece on the fixed scale base to generate an induction signal and feedback it to the host computer, the position of the moving scale base within which counter electrode and the displacement position within the counter electrode can be obtained, and thus the absolute displacement value of the two-dimensional time grating in the Y direction can be obtained. Finally, by adding the two position quantities, the absolute displacement value of the two-dimensional time grating can be obtained, thereby realizing the absolute displacement measurement of the planar two-dimensional time grating displacement sensor in the XOY plane.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. On the premise of ensuring the stability, real-time performance, and high resolution of the sensor, it realizes the integrated planar two-dimensional absolute linear displacement measurement. Compared with the incremental measurement method, the present invention can obtain the current absolute planar position when powered on, and has the advantages of eliminating the cumulative error of the sensor, not requiring manual zeroing when powered on, and the data not being lost when powered off.

[0026] 2. The absolute planar two-dimensional displacement sensor adopts a non-contact measurement method, has strong anti-interference ability, can adapt to relatively harsh working environments, and has a low cost.

[0027] 3. The sensor of the present invention has a simple structure, a wide measurement range, and a more extensive application. Description of the Drawings

[0028] Figure 1 It is a schematic diagram of the corresponding relationship between the fixed scale base and the moving scale base in Embodiment 1.

[0029] Figure 2 It is a schematic diagram of the arrangement of the excitation pole pieces on the fixed scale base in Embodiment 1.

[0030] Figure 3 It is a schematic diagram of the arrangement of the induction units on the moving scale base in Embodiment 1.

[0031] Figure 4 For Figure 3 It is a schematic diagram of the structure of a single induction unit in

[0032] Figure 5 It is a schematic diagram of the measurement method of the present invention.

[0033] Figures 6 to 9 It is a state diagram of the moving scale base on the fixed scale base in other embodiments. Specific embodiments

[0034] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0035] As Figures 1 to 4 shown, the absolute planar two-dimensional time grating displacement sensor based on an alternating electric field of the present invention includes a fixed scale base 1 and a moving scale base 2. The lower surface of the moving scale base 2 is installed parallel and facing the upper surface of the fixed scale base 1, with a gap of d = 1 mm left.

[0036] As Figure 2 shown, 32 rows of excitation electrodes (i.e., m = 16, that is, k2 = 4) are arranged side by side on the upper surface of the fixed scale base 1. Each row of excitation electrodes is composed of 16 identical square excitation electrode plates 15 (i.e., n = 16, that is, k1 = 4) evenly arranged along the X-axis direction. The distance Ie between adjacent two square excitation electrode plates 15 is 6 mm, and the width Le of one square excitation electrode plate 15 is 4 mm. The distance between adjacent two rows of excitation electrodes along the Y-axis direction is equal to 1 mm. The starting positions of the odd-numbered rows of excitation electrodes (i.e., the 1st row, the 3rd row,..., the 29th row, the 31st row of excitation electrodes) along the X-axis direction are the same, and the starting positions of the even-numbered rows of excitation electrodes (i.e., the 2nd row, the 4th row,..., the 30th row, the 32nd row of excitation electrodes) along the X-axis direction are the same. The starting position of the odd-numbered rows of excitation electrodes along the X-axis direction is offset by 5 mm from the starting position of the even-numbered rows of excitation electrodes along the X-axis direction.

[0037] In the 16x16 excitation electrode array composed of all the even-numbered rows of excitation electrodes, all the excitation electrodes (16 excitation electrode plates) in each column are respectively connected in series through excitation signal leads to form an X excitation unit, thus forming 16 X excitation units; starting from the first one, every four X excitation units successively form an X excitation pair stage, with a total of 4 X excitation pair stages; the four X excitation units in each X excitation pair stage are successively called XA excitation unit, XB excitation unit, XC excitation unit, and XD excitation unit. The 16 X excitation units are numbered 1, 2, 3,..., 16 in sequence along the positive X-axis direction. Then the 1st, 5th, 9th, and 13th X excitation units are XA excitation units, the 2nd, 6th, 10th, and 14th X excitation units are XB excitation units, the 3rd, 7th, 11th, and 15th X excitation units are XC excitation units, and the 4th, 8th, 12th, and 16th X excitation units are XD excitation units.

[0038] In the 16x16 excitation electrode array composed of excitation electrodes in all odd rows, all the excitation electrodes (16 excitation pole pieces) in each row are respectively connected through excitation signal leads to form Y excitation units, thus forming 16 Y excitation units; starting from the first one, every four Y excitation units successively form a Y excitation pair stage, with a total of 4 Y excitation pair stages; the four Y excitation units in each Y excitation pair stage are successively called YA excitation unit, YB excitation unit, YC excitation unit, and YD excitation unit. The 16 Y excitation units are numbered 1, 2, 3, …, 16 in sequence along the positive Y-axis direction. Then, the 1st, 5th, 9th, and 13th Y excitation units are YA excitation units, the 2nd, 6th, 10th, and 14th Y excitation units are YB excitation units, the 3rd, 7th, 11th, and 15th Y excitation units are YC excitation units, and the 4th, 8th, 12th, and 16th Y excitation units are YD excitation units.

[0039] In this embodiment, the width of the opposed pole W = 4(Le + Ie) = 40 mm, and there are 4 opposed poles in the X-axis direction and also 4 opposed poles in the Y-axis direction.

[0040] See Figure 3 and Figure 4 , an induction electrode is provided on the lower surface of the moving scale base body, and the induction electrode on the moving scale base body is opposite to the excitation electrode on the fixed scale base body. The induction electrode is composed of r induction units arranged in a matrix, and the distance between adjacent two induction units is Ii; each induction unit is composed of 4 identical square induction pole pieces a, b, c, and d arranged in a 2x2 manner, the side length of each induction pole piece is Li, the distance between adjacent two induction pole pieces is Ii, and Li + Ii = 2(Le + Ie); the induction pole pieces a in all induction units are connected to form an a induction group, the induction pole pieces b in all induction units are connected to form a b induction group, the induction pole pieces c in all induction units are connected to form a c induction group, and the induction pole pieces d in all induction units are connected to form a d induction group.

[0041] Figure 3 In the embodiment shown in

[0042] The present invention further includes a driving circuit, which is used to drive 4 X excitation pairs and 4 Y excitation pairs in sequence to generate excitation signals. When driving each X excitation pair, sinusoidal excitation signals with the same amplitude and frequency and with phases successively differing by π / 2 are respectively applied to the XA excitation unit, the XB excitation unit, the XC excitation unit, and the XD excitation unit; when driving each Y excitation pair, sinusoidal excitation signals with the same amplitude and frequency and with phases successively differing by π / 2 are respectively applied to the YA excitation unit, the YB excitation unit, the YC excitation unit, and the YD excitation unit. When electric field coupling occurs between the moving scale base and the fixed scale base, the a, b, c, d induction groups respectively generate four induction signals Ua, Ub, Uc, Ud for the X excitation pairs and the Y excitation pairs, and by respectively processing the four induction signals generated by the X excitation pairs and the Y excitation pairs, the linear displacement of the moving scale base relative to the fixed scale base in the X-axis direction and the linear displacement in the Y-axis direction can be obtained.

[0043] A coupling capacitor is formed between the induction unit on the lower surface of the moving scale base 2 and the square excitation pole piece 15 on the upper surface of the opposed fixed scale base 1. During measurement, along the X direction, sinusoidal excitation signals U j3 、XB j3 、XC j3 、XD j3 are successively applied to the excitation units, where U A =U m sinωt, U B =U m cosωt, U C =-U m sinωt, U D =-U m cosωt, and j3 successively takes all integers from 1 to k1. Along the Y direction, sinusoidal excitation signals U j4 、YB j4 、YC j4 、YD j4 are successively applied to the excitation units, where U A =U m sinωt, U B =U m cosωt, U C =-U m sinωt, U D =-U m cosωt, and j4 successively takes all integers from 1 to k2 (which is equivalent to respectively determining the position of the moving scale base in the XY direction by scanning in the XY directions). In the embodiment, the amplitude U m of the excitation signal is 5V, the frequency f = 40KHz, and the angular frequency ω = 2πf = 8×10 4 π.

[0044] When the moving scale base 2 moves relative to the fixed scale base 1 along the X-axis direction, the a, b, c, d induction groups respectively generate U a 、U b 、U c 、U d four-way induction electrical signals, and the expressions are:

[0045]

[0046] When the moving scale base 2 moves relative to the fixed scale base 1 along the Y-axis direction, the a, b, c, d induction groups respectively generate U a 、U b 、U c 、U d four-way induction electrical signals, and the expressions are:

[0047]

[0048] In the formula, Ke is the electric field coupling coefficient, and x and y are the linear displacements of the moving scale base 2 relative to the fixed scale base 1 in the X-axis direction and in the Y-axis direction respectively.

[0049] When the induction electrodes on the moving scale base generate induction signals due to electric field coupling, it indicates that the position of the moving scale base has been scanned. At this time, the excitation signals are stopped from being applied to the remaining X or Y excitation pair stages. Next, the above four-way electrical signals are processed respectively to obtain the X-axis sine wave signal U x and the Y-axis sine wave signal U y . After the X-axis sine wave signal U x and the Y-axis sine wave signal U y are shaped into square waves by the shaping circuit, they are simultaneously sent into the FPGA for phase discrimination processing, compared with a co-frequency reference square wave, and the phase difference is represented by the number of high-frequency clock pulses interpolated. After conversion, the linear displacement x of the moving scale base 2 relative to the fixed scale base 1 in the X-axis direction and the linear displacement y in the Y-axis direction can be obtained. The measurement process of the present invention can be referred to simultaneously in Figure 5 .

[0050] The present invention sequentially applies sinusoidal excitation signals with the same frequency and equal amplitude and a phase difference of 90° to four excitation units of a scale base along the X direction and the Y direction in sequence. When an electric field coupling occurs with the induction pole pieces of a moving scale base, the induction pole pieces output induction signals, thereby locating in which pair of poles the moving scale base is located in the fixed scale base. Then, the upper computer judges the position of the moving scale base within the pair of poles, and finally obtains the absolute displacement value of the two-dimensional time grating. Since one pair of excitation poles has a fixed length W, and the excitation pole pieces and the spacing within the pair of poles also have widths Le and Ie, the linear displacement x in the X-axis direction is x = x1W + x2Le + x3Ie, where x1 is the number of complete pairs of poles scanned in the X-axis direction, and x2 and x3 are the numbers of the pole pieces / gaps within the next pair of poles except for the complete pairs of poles.

[0051] If, as shown in Figure 2 , the excitation signal is applied to the X excitation pair of poles from left to right, then the induction signals of the induction group composed of the induction pole pieces corresponding to the left column where each induction unit is located (i.e., the Figure 4 a and b induction pole pieces shown) are taken for resolution processing; if the excitation signal is applied to the X excitation pair of poles from right to left, then the induction signals of the induction group composed of the induction pole pieces corresponding to the right column where each induction unit is located (i.e., the Figure 4 c and d induction pole pieces shown) are taken for resolution processing;

[0052] If, as shown in Figure 2 , the excitation signal is applied to the Y excitation pair of poles from top to bottom, then the induction signals of the induction group composed of the induction pole pieces in the row above each induction unit (i.e., the Figure 4 b and d induction pole pieces shown) are taken for resolution processing; if the excitation signal is applied to the Y excitation pair of poles from bottom to top, then the induction signals of the induction group composed of the induction pole pieces in the row below each induction unit (i.e., the Figure 4 a and c induction pole pieces shown) are taken for resolution processing.

[0053] During actual measurement, the excitation signal can be applied to k1 X excitation pairs of poles and k2 Y excitation pairs of poles simultaneously, that is, the displacement measurements in the X-axis and Y-axis directions are realized simultaneously. Or the excitation signal can be applied to k1 X excitation pairs of poles and k2 Y excitation pairs of poles separately, that is, the displacement measurements in the X-axis and Y-axis directions are realized successively.

[0054] Figures 6 to 9 The state diagrams of the moving scale base on the fixed scale base in another four embodiments of the present invention are shown.

[0055] 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 them. Although the applicant has described the present invention in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present invention without departing from the purpose and scope of the present technical solution should be covered within the scope of the claims of the present invention.

Claims

1. An absolute planar two-dimensional time grating displacement sensor based on an alternating electric field, comprising a fixed scale base body and a moving scale base body. The lower surface of the moving scale base body is installed parallel and facing the upper surface of the fixed scale base body with a gap left. On the upper surface of the fixed scale base body, 2m rows of excitation electrodes are arranged side by side. Each row of excitation electrodes is composed of the same n square excitation pole pieces evenly arranged along the X-axis direction. The distance Ie between two adjacent square excitation pole pieces is greater than the width Le of one square excitation pole piece. The distance between two adjacent rows of excitation electrodes along the Y-axis direction is (Ie - Le) / 2, and the starting positions along the X-axis direction are staggered by (Ie + Le) / 2: the starting positions of the odd-numbered rows of excitation electrodes along the X-axis direction are the same, and the starting positions of the even-numbered rows of excitation electrodes along the X-axis direction are the same. Among them, n = 4k1, m = 4k2, where k1 and k2 are both positive integers; The lower surface of the moving scale base body is provided with induction electrodes, and the induction electrodes on the moving scale base body are opposite to the excitation electrodes on the fixed scale base body; the induction electrodes are composed of r induction units arranged in a matrix, and the distance between adjacent two induction units is Ii; each induction unit is composed of the same 4 square induction poles a, b, c, and d arranged in a 2x2 manner, the side length of each induction pole is Li, the distance between adjacent two induction poles is Ii, and Li + Ii = 2(Le + Ie); the induction poles a in all induction units are connected together to form an a induction group, the induction poles b in all induction units are connected together to form a b induction group, the induction poles c in all induction units are connected together to form a c induction group, and the induction poles d in all induction units are connected together to form a d induction group; characterized in that: In the excitation electrode array composed of all odd-row excitation electrodes, all the excitation electrodes in each row are respectively connected together to form a Y excitation unit, thus forming m Y excitation units; starting from the first one, every four Y excitation units successively form a Y excitation pair stage, with a total of k2 Y excitation pair stages; the four Y excitation units in each Y excitation pair stage are successively called a YA excitation unit, a YB excitation unit, a YC excitation unit, and a YD excitation unit; In the excitation electrode array composed of all even-row excitation electrodes, all the excitation electrodes in each column are respectively connected together to form an X excitation unit, thus forming n X excitation units; starting from the first one, every four X excitation units successively form an X excitation pair stage, with a total of k1 X excitation pair stages; the four X excitation units in each X excitation pair stage are successively called an XA excitation unit, an XB excitation unit, an XC excitation unit, and an XD excitation unit; It further includes a drive circuit, and the drive circuit is used to sequentially drive k1 X excitation pair stages and k2 Y excitation pair stages to generate excitation signals; when driving each X excitation pair stage, sinusoidal excitation signals with equal amplitude and the same frequency and with phases successively differing by π / 2 are respectively applied to the XA excitation unit, the XB excitation unit, the XC excitation unit, and the XD excitation unit; when driving each Y excitation pair stage, sinusoidal excitation signals with equal amplitude and the same frequency and with phases successively differing by π / 2 are respectively applied to the YA excitation unit, the YB excitation unit, the YC excitation unit, and the YD excitation unit; when electric field coupling occurs between the moving scale base body and the fixed scale base body, the a, b, c, and d induction groups respectively generate four-way induction signals for the X excitation pair stage and the Y excitation pair stage, and after being processed respectively, the linear displacement of the moving scale base body relative to the fixed scale base body in the X-axis direction and the linear displacement in the Y-axis direction are obtained.

2. The absolute planar two-dimensional time grating displacement sensor based on an alternating electric field according to claim 1, characterized in that: Let the width of the induction unit be W, and it satisfies W = 2(Li + Ii) = 4(Le + Ie).

3. An absolute planar two-dimensional time grating displacement measurement method based on an alternating electric field, characterized in that: It is implemented by using the absolute two-dimensional planar time grating displacement sensor based on alternating electric field described in any one of claims 1 - 2; during measurement, Apply the excitation signal to k1 X excitation pair stages in sequence. When the induction electrode on the moving scale base generates an induction signal due to electric field coupling, stop applying the excitation signal to the remaining X excitation pair stages. By processing the four-channel electrical signals generated by the a, b, c, and d induction groups, obtain which X excitation pair pole the moving scale base is located in and the displacement position within the X excitation pair pole, so as to obtain the two-dimensional time grating absolute displacement value of the moving scale base relative to the fixed scale base in the X direction; Apply the excitation signal to k2 Y excitation pair stages in sequence. When the induction electrode on the moving scale base generates an induction signal due to electric field coupling, stop applying the excitation signal to the remaining Y excitation pair stages. By processing the four-channel electrical signals generated by the a, b, c, and d induction groups, obtain which Y excitation pair pole the moving scale base is located in and the displacement position within the Y excitation pair pole, so as to obtain the two-dimensional time grating absolute displacement value of the moving scale base relative to the fixed scale base in the Y direction; Then, take the two-dimensional time grating absolute displacement value in the X direction and the two-dimensional time grating absolute displacement value in the Y direction as the coordinates of the moving scale base in the X direction and Y direction, that is, obtain the absolute displacement of the moving scale base.

4. The absolute planar two-dimensional time grating displacement measurement method based on an alternating electric field according to claim 3, characterized in that: If the excitation signal is applied to the X excitation pair stages from left to right, then take the induction signals of the induction group composed of the induction pole pieces corresponding to the left column where each induction unit is located for calculation and processing; if the excitation signal is applied to the X excitation pair stages from right to left, then take the induction signals of the induction group composed of the induction pole pieces corresponding to the right column where each induction unit is located for calculation and processing; If the excitation signal is applied to the Y excitation pair stages from top to bottom, then take the induction signals of the induction group composed of the induction pole pieces in the upper row of each induction unit for calculation and processing; if the excitation signal is applied to the Y excitation pair stages from bottom to top, then take the induction signals of the induction group composed of the induction pole pieces corresponding to the lower row of each induction unit for calculation and processing.

5. A method for measuring the absolute planar two-dimensional time grating displacement based on an alternating electric field according to claim 3, characterized in that: Apply the excitation signal to the k1 X excitation pair stages and the k2 Y excitation pair stages simultaneously.

6. The absolute planar two-dimensional time grating displacement measurement method based on an alternating electric field according to claim 3, wherein: Apply the excitation signal to the k1 X excitation pair stages and the k2 Y excitation pair stages separately.

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