Single code channel absolute type linear displacement encoder and measuring method

Abstract

The invention relates to the technical field of measuring sensors, in particular to a single-code-channel absolute linear displacement encoder and a measuring method. The fixed ruler and the reading head are arranged in parallel, a gap is reserved between the fixed ruler and the reading head, the fixed ruler is composed of a fixed ruler base body and a closed plane coil attached to the top face of the fixed ruler, the fixed ruler is a rectangular long ruler with the length L, the width W and the thickness H, and the length direction is the encoder measuring direction; the reading head consists of a sensing unit and a shell; the sensing unit is a rectangular short ruler with the length of Lm, the width of Wm and the thickness of Hm, and each direction is parallel to the corresponding direction of the fixed ruler. According to the invention, high-precision absolute linear measurement can be realized only by means of a single excitation channel in a large range, and measurement errors caused by interference between coils of a traditional fine machine and a coarse machine are effectively avoided; and meanwhile, the structure is simplified, the size is smaller, the sizing base body does not need a lead, the applicability and the measurement precision are improved, and the device is suitable for high-precision linear displacement detection occasions.

Description

Technical Field

[0001] This invention relates to the field of measurement sensor technology, and in particular to a single-track absolute linear displacement encoder and measurement method. Background Technology

[0002] Precision linear displacement measurement technology is widely used in precision testing instruments, national defense weaponry, aerospace, semiconductor manufacturing, and medical devices—fields with extremely high requirements for motion control accuracy. Displacement measurement is divided into incremental and absolute measurement. Incremental encoders are less expensive and easier to install and maintain, but their measurements are susceptible to interference, require consistent motion, and are affected by accumulated errors. Absolute encoders, on the other hand, offer unique position information for each output, require no memory of position information, and do not require finding a zero reference point. Position information can be read as needed during measurement. Therefore, absolute encoders possess advantages such as excellent anti-interference capabilities, high data reliability, direct position information reading, no loss of position information when power is off, and no error accumulation, giving them broad market application potential and unique technological advantages.

[0003] In existing technologies, magnetic induction absolute displacement sensors often employ a dual-row structure for encoding. However, improving the signal-to-noise ratio requires high-frequency excitation signals, which limits the improvement of resolution and results in a large sensor size, making it difficult to meet the requirements of small-volume installation. Capacitive grating sensors are sensitive to the environment and suffer from temperature drift. Furthermore, most of the above sensors require separate leads for the moving and fixed scales, which also significantly limits their effective measurement range. Therefore, we propose a single-track absolute linear displacement encoder and measurement method. Summary of the Invention

[0004] The purpose of this invention is to provide a single-track absolute linear displacement encoder and measurement method to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A single-track absolute linear displacement encoder includes a fixed scale and a reading head arranged parallel to each other with a pre-reserved gap between them. The fixed scale consists of a fixed scale base and a closed planar coil attached to the top surface of the fixed scale. The fixed scale is a rectangular ruler with a length L, a width W, and a thickness H, and the length direction is the measurement direction of the encoder.

[0007] The reading head consists of a sensing unit and a housing; the sensing unit is a rectangular short ruler with a length of Lm, a width of Wm, and a thickness of Hm, and all directions are parallel to the corresponding directions of the fixed ruler.

[0008] Preferably, the sensing unit includes an excitation winding, two coarse machining induction windings, and two fine machining induction windings.

[0009] Preferably, the closed planar coil on the top surface of the fixed-length coil is composed of:

[0010] Line segment X1: Curve S1: T1 is the precision coefficient, which is determined by the precision pitch L1. T2 is the roughing coefficient, which is determined by the roughing mill pitch L2. ;

[0011] Line segment X2: Curve S2: The configuration consists of L1, L2, and T1 and T2 being coprime. Parameter A1 corresponds to the precision machining proportional coefficient, and parameter A2 corresponds to the rough machining proportional coefficient, thus ensuring that each position within the sensor's range has a unique correspondence.

[0012] Preferably, the excitation winding is a set of planar rectangular helical coils, the length and width directions of which are parallel to the length and width directions of the sensing unit, respectively. The planar rectangular helical coils have ≥1 turn. The planar rectangular helical coils are distributed on a single plane or on multiple parallel planes spaced 0.05mm~0.2mm apart, parallel to the bottom surface of the sensing unit. The inlet and outlet ends of the planar rectangular helical coils are a and b, respectively. The area contained in the innermost loop of the planar rectangular helical coil is a rectangle with length Le and width We, where Le>xx and We>Ws.

[0013] Preferably, the two precision induction windings are arranged in the area surrounded by the innermost coil of the spiral coil on the bottom surface of the sensing unit, and are respectively the first precision induction winding and the second precision induction winding.

[0014] The first precision induction winding includes four coils j 11 j 12 j 13 j 14 The second precision induction winding also includes four coils. 21 j 22 j 23 j 24 The eight coils of the first and second precision induction windings are identical in size and shape, with a length of L. j Width is W j The rectangle has eight coils whose length and width directions are parallel to the length and width directions of the sensing unit, respectively, where: L j For any value that is not an integer multiple of L1, Wj >Ws and W j <We; The 8 rectangular coils of the precision machine induction winding are flush in the length direction.

[0015] Preferably, the j of the precision machine induction winding 11 and j 12 are connected in reverse series, and j 11 and j 12 Two rectangles are arranged at positions with an odd multiple interval of L1 / 2 in the length direction from the center; j of the first precision machine induction winding 13 and j 14 are connected in reverse series, and j 13 and j 14 Two rectangles are arranged at positions with an odd multiple interval of L1 / 2 in the length direction from the center; j of the first precision machine induction winding 12 and j 13 are connected in the same direction in series, j 11 and j 13 Two rectangles are arranged at positions with an integer multiple interval of L2 in the length direction from the center; j of the second precision machine induction winding 21 and j 22 are connected in reverse series, and j 21 and j 22 Two rectangles are arranged at positions with an odd multiple interval of L1 / 2 in the length direction from the center; j of the second precision machine induction winding 23 and j 24 are connected in reverse series, and j 23 and j 24 Two rectangles are arranged at positions with an odd multiple interval of L1 / 2 in the length direction from the center, and j of the second precision machine induction winding 22 and j 23 are connected in the same direction in series, j 21 and j 23 Two rectangles are arranged at positions with an odd multiple interval of L1 / 4 in the length direction from the center; j of the first precision machine induction winding 11 and j of the second precision machine induction winding 21 Two rectangles are arranged at positions with an odd multiple interval of L1 / 4 in the length direction from the center.

[0016] Preferably, the two rough machine induction windings are arranged on a plane parallel to the bottom surface of the sensing unit and spaced 0.05 - 0.1 mm apart, and within the area enclosed by the innermost coil of the excitation winding, which are the first rough machine induction winding and the second rough machine induction winding respectively;

[0017] The first rough machine induction winding includes four coils C 11 , C 12 , C 13 , C 14, the second rough machine induction winding also includes four coils C 21 , C 22 , C 23 , C 24 , the 8 coils of the first rough machine induction winding and the second rough machine induction winding are of the same size and shape, with a length of L c , and a width of W c The rectangle, the length and width directions of the 8 coils are parallel to the length and width directions of the sensing unit respectively, where L c is an arbitrary value that is not an integer multiple of L2, and W c >Ws and W c <We; the 8 rectangular coils of the rough machine induction winding are flush in the length direction.

[0018] Preferably, the C of the first rough machine induction winding 11 and C 12 are connected in reverse series, and C 11 and C 12 The two rectangles are arranged at positions with an odd multiple interval of L2 / 2 in the length direction; C of the first rough machine induction winding 13 and C 14 are connected in reverse series, and C 13 and C 14 The two rectangles are arranged at positions with an odd multiple interval of L2 / 2 in the length direction; C of the first rough machine induction winding 12 and C 13 are connected in the same direction in series, C 11 and C 13 The two rectangles are arranged at positions with an integer multiple interval of L1 in the length direction;

[0019] The C of the second rough machine induction winding 21 and C 22 are connected in reverse series, and C 21 and C 22 The two rectangles are arranged at positions with an odd multiple interval of L2 / 2 in the length direction; C of the second rough machine induction winding 23 and C 24 are connected in reverse series, and C 23 and C 24 The two rectangles are arranged at positions with an odd multiple interval of L2 / 2 in the length direction; C of the second rough machine induction winding 22 and C 23 are connected in reverse series, C 21 and C 23 The two rectangles are arranged at positions with an integer multiple interval of L1 in the length direction;

[0020] The C of the first rough machine induction winding 11C of the second coarse machine induction winding 21 Two rectangles are arranged at their centers at odd multiples of L2 / 4 in the length direction.

[0021] A measurement method for a single-track absolute linear displacement encoder, applicable to a single-track absolute linear displacement encoder, includes the following steps:

[0022] S1: During measurement, a high-frequency sinusoidal excitation signal is applied to the excitation coil on the moving scale base, and the secondary excitation coil on the fixed scale base generates a corresponding induced current.

[0023] S2: The coarse machine induction pole and the fine machine induction pole independently output four signals: SIN+, SIN-, COS+ and COS-. The COS+ and COS- signals are digitally phase-shifted to make them orthogonal to the SIN+ and SIN- signals in both space and time. Then, the fine machine position sensing traveling wave signal and the coarse machine position sensing traveling wave signal are obtained by superposition and synthesis.

[0024] S3: Process the traveling wave signals from the precision and roughing machines to obtain the absolute displacement value of the sensor within the displacement measurement range.

[0025] It is clear without a doubt that the technical solution described above in this application can solve the technical problem that this application aims to address.

[0026] Meanwhile, through the above technical solutions, the present invention has at least the following beneficial effects:

[0027] 1. This invention ensures the uniqueness of all positions of the encoder within the set measurement range by attaching a closed planar coil with a specific shape to the top surface of the fixed-length substrate. This fundamentally eliminates the mutual inductance phenomenon between the excitation coils caused by the dual excitation channel encoding method of traditional absolute encoders, effectively reduces crosstalk in the encoder system, and improves the accuracy of absolute measurement and the integration of the encoder.

[0028] 2. The precision induction winding and coarse induction winding of the encoder achieve effective acquisition of precision induction signals and coarse induction signals through specific shapes, sizes and arrangements, which effectively reduces the size of the encoder in the horizontal or vertical direction, so as to adapt to the more confined measurement space.

[0029] 3. A leadless, specific planar coil is used on the top surface of the fixed-length base, which enables the encoder to adapt to more measurement environments and realize passive sensing of sensor signals, making the installation and maintenance of the encoder more convenient.

[0030] 4. The precision induction winding and coarse induction winding of the encoder of the present invention are arranged and wound in a specific manner, which can effectively eliminate superimposed interference and common mode signals and improve the signal-to-noise ratio of the encoder system.

[0031] 5. This invention only requires one high-frequency sinusoidal excitation signal to be supplied to a single-track absolute displacement encoder, which avoids the problem of the traditional phase detection method requiring two excitation signals to be input to the encoder system to obtain the encoder rotation angle, resulting in the inability to achieve absolute orthogonality between the two signals and the inability to keep the frequencies consistent in real time, thus reducing the requirements for the excitation signal and improving the accuracy of encoder measurement.

[0032] 6. The encoder of the present invention has a compact overall structure and is suitable for various industrial measurement and control applications, especially for high-precision CNC machine tools, semiconductor equipment, automated production lines and precision testing devices. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a three-dimensional structural diagram of the measuring scale and reading head of the present invention;

[0035] Figure 2 For the present invention Figure 1 Enlarged view of point A in the middle;

[0036] Figure 3 This is a schematic diagram of the fixed-length structure of the present invention;

[0037] Figure 4 This is a schematic diagram of the reading head of the present invention;

[0038] Figure 5 This is a schematic diagram of the sensing unit of the present invention;

[0039] Figure 6 This is a spatial schematic diagram of the excitation coil and the reading head induction coil on the fixed-length base of the present invention.

[0040] The attached diagram lists the components represented by each number as follows:

[0041] In the diagram: 1. Fixed length; 11. Planar closed coil; 2. Reading head; 21. Coarse machining induction winding; 22. Fine machining induction winding; 23. Excitation winding; 24. Housing. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] Example 1

[0044] Reference Figure 1-6 A single-track absolute linear displacement encoder includes a fixed scale 1 and a reading head 2 arranged parallel to each other with a pre-difference gap. The fixed scale base has a length of 542.4 mm, a width of 13.3 mm, and a thickness of 1.6 mm. A closed planar coil 11 with a specific shape is attached to its top surface. This closed planar coil 11 is formed by stacking the coils along the centerline of its length direction. The closed planar coil 11 with a specific shape is composed of line segment X1y. X1 =6mm, curve S1 line segment X2y X2 =6.66mm, curve S2 The configuration is as follows: A1 and A2 are both 1, L1 is 4.11, L2 is 5.57, and N is 3. Analysis easily shows that the encoder position is unique within the encoder's range of 0 to 540 mm. The fixed-length base is manufactured using PCB technology, and the closed coil on its top surface is made of copper wire.

[0045] The reading head 2 is a rectangular short ruler with a length of 62.5 mm, a width of 25.7 mm, and a thickness of 1.6 mm. The reading head 2 is parallel to the corresponding direction of the fixed ruler 1 in all directions. The reading head 2 includes a sensing unit and a housing 24. The bottom surface of the sensing unit and the top surface of the fixed ruler are parallel and directly opposite each other, separated by a distance of 0.5 mm. The sensing unit includes an excitation winding 23, two precision induction windings 22, and two roughing induction windings 21. The excitation winding 23 is a set of planar rectangular helical coils, each with three turns distributed on the same plane. The input and output ends of the parallel rectangular helical coils are a and b, respectively, with a distance of 2 mm between a and b. The outermost layer of the planar rectangular coil has a length of 64 mm and a rectangular width of 13 mm. Two precision induction windings 22 are arranged in the area surrounded by the innermost coil of the excitation winding 23 on the bottom surface of the sensing unit. They are the first precision induction winding and the second precision induction winding, respectively. The first precision induction winding contains four coils j. 11 j 12 j 13 j 14 The second precision induction winding also contains four coils. 21 j 22 j 23 j 24The first and second precision induction windings each have eight coils that are identical in size and shape, measuring 5.57 mm in length and 12 mm in width. The length and width directions of these eight coils are parallel to the length and width directions of the sensing unit, respectively. The eight rectangular coils of the precision induction windings are aligned along their length. The first precision induction winding... 11 and j 12 Reverse serial connection, and j 11 and j 12 Two rectangles are arranged at the center, 6.17 mm apart in the longitudinal direction. The first precision induction winding's j... 13 and j 14 Reverse serial connection, and j 13 and j 14 Two rectangles are arranged at the center, 6.17 mm apart in the longitudinal direction; j of the first precision induction winding 12 and j 13 Series in the same direction, j 11 and j 13 Two rectangles are arranged at the center, 13.93 mm apart along their length. The second precision induction winding j... 21 and j 22 Reverse serial connection, and j 21 and j 22 Two rectangles are arranged at the center, 6.17 mm apart in the longitudinal direction, and the second precision induction winding j 23 and j 24 Reverse serial connection, and j 23 and j 24 Two rectangles are arranged at the center, 6.17 mm apart in the longitudinal direction, and the second precision induction winding j 22 and j 23 Series in the same direction, j 21 and j 23 Two rectangles are arranged at the center, 13.93 mm apart in the longitudinal direction. The j-shaped winding of the first precision induction winding... 11 j of the second precision machine induction winding 21 Two rectangles are arranged at their centers, 29.79 mm apart along their length. Two coarse machining windings 21 are arranged on a plane parallel to the bottom surface of the sensing unit and spaced 0.5 mm apart, tangent to the area enclosed by the innermost coil of the excitation winding 23. These are the first and second coarse machining induction windings, respectively. The first coarse machining induction winding contains four coils C. 11 C 12 C 13 C 14 The second coarse-rolled induction winding also contains four coils C. 21 C 22 C 23 C 24The first and second coarse-machine induction windings each have eight coils that are identical in size and shape, measuring 4.11 mm in diameter and 12 mm in width. The length and width directions of these eight coils are parallel to the length and width directions of the sensing unit, respectively. The eight rectangular coils of the coarse-machine induction windings are aligned along their length, according to the C-shape of the first coarse-machine induction winding. 11 and C 12 Reverse series connection, and C 11 and C 12 Two rectangles are arranged at the center, 8.36 mm apart in the longitudinal direction. The C of the first roughing winding... 13 and C 14 Reverse series connection, and C 13 and C 14 Two rectangles are arranged at the center, 8.36 mm apart in the longitudinal direction. The C of the first roughing winding... 12 and C 14 Reverse series, C 11 and C 13 Two rectangles are arranged at the center, 14.385 mm apart in the longitudinal direction; the C of the second coarse-grained induction winding. 23 and C 24 Reverse series connection, and C 23 and C 24 Two rectangles are arranged at the center, 8.36 mm apart in the longitudinal direction, and the C of the second coarse-coated induction winding. 22 and C 23 Reverse series, C 21 and C 23 Two rectangles are arranged at the center, 8.36 mm apart in the longitudinal direction. The C of the first roughing winding... 11 C of the second coarse machine induction winding 21 Two rectangles are placed at the center, 14.385 mm apart in the longitudinal direction.

[0046] The induction poles A and C generate signals SIN+(J) and SIN-(J), respectively, while the induction poles B and D generate signals COS+(J) and COS-(J), respectively. By digitally shifting terms, the signals COS+(J) and COS-(J) generated by the induction poles B and D are kept at a time-domain difference of π / 2 from the signals SIN+(J) and SIN-(J) generated by the induction poles A and C, respectively. This ensures that the four induction signals are pairwise orthogonal in both the time and spatial domains. Superimposing SIN+(J) and SIN-(J), and then superimposing the digitally shifted signals COS+(J) and COS-(J), finally yields the traveling wave signal of the induced electromotive force of the machinery through data processing.

[0047] Coarse machine induction poles A and C generate signals SIN+(C) and SIN-(C), respectively, while fine machine induction poles B and D generate signals COS+(C) and COS-(C), respectively. By digitally shifting terms, the signals COS+(C) and COS-(C) generated by fine machine induction poles B and D are kept at a time-domain difference of π / 2 from the signals SIN+(C) and SIN-(C) generated by fine machine induction poles A and C, respectively. This ensures that the four induction signals are pairwise orthogonal in both the time and spatial domains. Superimposing SIN+(C) and SIN-(C), and then superimposing the digitally shifted signals COS+(C) and COS-(C), finally, through data processing, yields the traveling wave signal of the fine machine induced electromotive force.

[0048] Example 2

[0049] A measurement method for a single-track absolute linear displacement encoder, applicable to a single-track absolute linear displacement encoder, includes the following steps: S1: During measurement, a high-frequency sinusoidal excitation signal is applied to the excitation coil on the moving scale base, and the secondary excitation coil on the fixed scale base generates a corresponding induced current.

[0050] S2: The coarse machine induction pole and the fine machine induction pole independently output four signals: SIN+, SIN-, COS+ and COS-. The COS+ and COS- signals are digitally phase-shifted to make them orthogonal to the SIN+ and SIN- signals in both space and time. Then, the fine machine position sensing traveling wave signal and the coarse machine position sensing traveling wave signal are obtained by superposition and synthesis.

[0051] S3: Process the traveling wave signals from the precision and roughing machines to obtain the absolute displacement value of the sensor within the displacement measurement range; during measurement, apply an excitation current signal to the excitation winding 23 on the reading head 2. Among them, the excitation current 0.5A, frequency f=4MHz, angular frequency =2πf=8π×10^6, the frequencies of the induced signal and the excitation signal are kept consistent.

[0052]

[0053]

[0054] in Let be the electric field induction coupling coefficient, and x be the displacement measurement quantity. Absolute displacement measurement, through a signal processing system, can obtain the phase values ​​generated by the roughing machine track displacement measurement unit and the precision machine track displacement measurement unit during displacement by calibrating the initial position and extracting the phase change information of the traveling wave from the obtained induced traveling wave signal. The phase angle difference between the roughing machine track displacement measurement unit and the precision machine track displacement measurement unit is... Based on the fact that the tooth pitch of the precision machine guide and the tooth pitch of the roughing machine guide are coprime, displacement measurement is achieved, and its calculation expression is as follows:

[0055]

[0056] K is an integer.

[0057] In summary:

[0058] This invention addresses the following technical problems: In existing technologies, magnetic induction absolute displacement sensors often employ a dual-row structure for encoding, but improving the signal-to-noise ratio relies on high-frequency excitation signals, which limits the improvement of resolution and results in a large sensor size, making it difficult to meet the requirements of small-volume installation. Capacitive grating sensors are sensitive to the environment and suffer from temperature drift. Furthermore, most of the above-mentioned sensors require separate leads for the moving and fixed scales, which also significantly limits their effective measurement range. By adopting the technical solutions of the above embodiments and through the aforementioned settings, this application can certainly solve the above-mentioned technical problems and achieve the following technical effects:

[0059] 1. This invention ensures the uniqueness of all positions of the encoder within the set measurement range by attaching a closed planar coil 11 with a specific shape to the top surface of the fixed-length substrate. This fundamentally eliminates the mutual inductance phenomenon between the excitation coils caused by the dual excitation channel encoding method of traditional absolute encoders, effectively reduces crosstalk in the encoder system, and improves the accuracy of absolute measurement and the integration of the encoder.

[0060] 2. The precision induction winding 22 and the coarse induction winding 21 of the encoder achieve effective acquisition of precision induction signals and coarse induction signals through specific shapes, sizes and arrangements, effectively reducing the size of the encoder in the horizontal or vertical direction to adapt to smaller measurement spaces.

[0061] 3. A leadless, specific planar coil is used on the top surface of the fixed-length base, which enables the encoder to adapt to more measurement environments and realize passive sensing of sensor signals, making the installation and maintenance of the encoder more convenient.

[0062] 4. The precision induction winding 22 and coarse induction winding 21 of the encoder of the present invention are arranged and wound in a specific manner, which can effectively eliminate superimposed interference and common mode signals and improve the signal-to-noise ratio of the encoder system.

[0063] 5. This invention only requires one high-frequency sinusoidal excitation signal to be supplied to a single-track absolute displacement encoder, which avoids the problem of the traditional phase detection method requiring two excitation signals to be input to the encoder system to obtain the encoder rotation angle, resulting in the inability to achieve absolute orthogonality between the two signals and the inability to keep the frequencies consistent in real time, thus reducing the requirements for the excitation signal and improving the accuracy of encoder measurement.

[0064] 6. The encoder of the present invention has a compact overall structure and is suitable for various industrial measurement and control applications, especially for high-precision CNC machine tools, semiconductor equipment, automated production lines and precision testing devices.

[0065] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] Obviously, the embodiments described above are merely some embodiments of the present invention, not all embodiments. The accompanying drawings show preferred embodiments of the present invention, but do not limit the patent scope of the present invention. The present invention can be implemented in many different forms; rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this invention.

Claims

1. A single-track absolute linear displacement encoder, comprising a fixed scale (1) and a reading head (2) arranged parallel to each other with a pre-difference gap between them, characterized in that: The fixed ruler (1) consists of a fixed ruler base and a closed planar coil (11) attached to the top surface of the fixed ruler (1). The fixed ruler (1) is a rectangular ruler with a length L, a width W, and a thickness H. The length direction is the encoder measurement direction. The reading head (2) consists of a sensing unit and a housing (24); the sensing unit is a rectangular short ruler with a length of Lm, a width of Wm, and a thickness of Hm, and each direction is parallel to the corresponding direction of the fixed ruler (1).

2. A single-track absolute linear displacement encoder according to claim 1, characterized in that, The sensing unit includes an excitation winding (23), two coarse machining induction windings (21) and two fine machining induction windings (22).

3. A single-track absolute linear displacement encoder according to claim 1, characterized in that, The closed planar coil (11) on the top surface of the fixed length (1) is made of: Line segment X1: Curve S1: T1 is the precision coefficient, which is determined by the precision pitch L1. T2 is the roughing coefficient, which is determined by the roughing mill pitch L2. ; line segment X2 curve S2 The configuration consists of L1, L2, and T1 and T2 being coprime. Parameter A1 corresponds to the precision machining proportional coefficient, and parameter A2 corresponds to the rough machining proportional coefficient, thus ensuring that each position within the sensor's range has a unique correspondence.

4. A single-track absolute linear displacement encoder according to claim 2, characterized in that, The excitation winding (23) is a set of planar rectangular spiral coils. The length and width directions of the planar rectangular spiral coils are parallel to the length and width directions of the sensing unit, respectively. The number of turns of the planar rectangular spiral coils is ≥1. The planar rectangular spiral coils are distributed on a plane or on multiple planes that are parallel to each other and spaced 0.05mm~0.2mm apart and parallel to the bottom surface of the sensing unit. The inlet and outlet ends of the planar rectangular spiral coils are a and b, respectively. The area contained in the innermost loop of the planar rectangular spiral coil is a rectangle with a length of Le and a width of We, where Le>xx and We>Ws.

5. A single-track absolute linear displacement encoder according to claim 4, characterized in that, The two precision induction windings (22) are arranged in the area surrounded by the innermost coil of the spiral coil of the excitation winding (23) on the bottom surface of the sensing unit, namely the first precision induction winding and the second precision induction winding. The first precision machine induction winding includes four coils j 11 , j 12 , j 13 , j 14 , and the second precision machine induction winding also includes four coils j 21 , j 22 , j 23 , j 24 . The eight coils of the first precision machine induction winding and the second precision machine induction winding are the same in size and shape, with a length of L j and a width of W j . The eight coils are rectangles, and the length and width directions of the eight coils are parallel to the length and width directions of the sensing unit respectively. Among them: L j is an arbitrary value that is not an integer multiple of L1, W j > Ws and W j < We; the eight rectangular coils of the precision machine induction winding (22) are flush in the length direction.

6. A single-track absolute linear displacement encoder according to claim 5, characterized in that, The j of the precision induction winding (22) 11 and j 12 Reverse serial connection, and j 11 and j 12 Two rectangles are arranged at their centers at odd multiples of L1 / 2 in the length direction; j of the first precision induction winding 13 and j 14 Reverse serial connection, and j 13 and j 14 Two rectangles are arranged at their centers at odd multiples of L1 / 2 in the length direction; j of the first precision induction winding 12 and j 13 Series in the same direction, j 11 and j 13 Two rectangles are arranged at the center, with a distance of L2 integer multiples between them in the length direction; the j of the second precision induction winding 21 and j 22 Reverse serial connection, and j 21 and j 22 Two rectangles are arranged at their centers at odd multiples of L1 / 2 in the length direction; the j of the second precision induction winding 23 and j 24 Reverse serial connection, and j 23 and j 24 Two rectangles are arranged at their centers at odd multiples of L1 / 2 in the length direction, and the j of the second precision induction winding... 22 and j 23 Series in the same direction, j 21 and j 23 Two rectangles are placed at their centers at intervals that are multiples of L2 along their length. j of the first precision machine induction winding 11 j of the second precision machine induction winding 21 Two rectangles are arranged at their centers at odd multiples of L1 / 4 apart along their length.

7. A single-track absolute linear displacement encoder according to claim 5, characterized in that, The two coarse mechanical induction windings (21) are arranged on a plane parallel to the bottom surface of the sensing unit and spaced 0.05~0.1mm apart. They are the first coarse mechanical induction winding and the second coarse mechanical induction winding, respectively, within the area surrounded by the innermost coil of the excitation winding (23). The first roughing machine induction winding includes four coils C 11 , C 12 , C 13 , C 14 , and the second roughing machine induction winding also includes four coils C 21 , C 22 , C 23 , C 24 , and the 8 coils of the first roughing machine induction winding and the second roughing machine induction winding are the same in size and shape, with a length of L c and a width of W c . The 8 coils are rectangles, and the length and width directions of the 8 coils are parallel to the length and width directions of the sensing unit respectively. Among them, L c is an arbitrary value that is not an integer multiple of L2, W c > Ws and W c < We; the 8 rectangular coils of the roughing machine induction winding (21) are flush in the length direction.

8. A single-track absolute linear displacement encoder according to claim 7, characterized in that, C of the first coarse-grained induction winding 11 and C 12 Reverse series connection, and C 11 and C 12 Two rectangles are arranged at points on the center that are at odd multiples of L2 / 2 in the length direction; C of the first coarse-rolled induction winding 13 and C 14 Reverse series connection, and C 13 and C 14 Two rectangles are arranged at points on the center that are at odd multiples of L2 / 2 in the length direction; C of the first coarse-rolled induction winding 12 and C 13 Series in the same direction, C 11 and C 13 Two rectangles are placed at their centers at intervals that are multiples of L1 along their length. C of the second coarse-coated induction winding 21 and C 22 Reverse series connection, and C 21 and C 22 Two rectangles are arranged at points at which they are spaced apart by an odd multiple of L2 / 2 along their length; the C of the second coarse-coated induction winding 23 and C 24 Reverse series connection, and C 23 and C 24 Two rectangles are arranged at points at which they are spaced apart by an odd multiple of L2 / 2 along their length; the C of the second coarse-coated induction winding 22 and C 23 Reverse series, C 21 and C 23 Two rectangles are placed at their centers at intervals that are multiples of L1 along their length. C of the first coarse-grained induction winding 11 C of the second coarse machine induction winding 21 Two rectangles are arranged at their centers at odd multiples of L2 / 4 in the length direction.

9. A measurement method for a single-track absolute linear displacement encoder, applicable to the single-track absolute linear displacement encoder described in any one of claims 1-8, characterized in that, Includes the following steps: S1: During measurement, a high-frequency sinusoidal excitation signal is applied to the excitation coil on the moving scale base, and the secondary excitation coil on the fixed scale base generates a corresponding induced current. S2: The coarse machine induction pole and the fine machine induction pole independently output four signals: SIN+, SIN-, COS+ and COS-. The COS+ and COS- signals are digitally phase-shifted to make them orthogonal to the SIN+ and SIN- signals in both space and time. Then, the fine machine position sensing traveling wave signal and the coarse machine position sensing traveling wave signal are obtained by superposition and synthesis. S3: Process the traveling wave signals from the precision and roughing machines to obtain the absolute displacement value of the sensor within the displacement measurement range.

Images