A multi-stage coarse high-precision novel translational-rotational platform photoelectric encoding measurement method

Abstract

The application discloses a kind of multi-stage coarse high-precision novel translational rotary platform photoelectric encoding measurement methods.The application relates to engineering surveying technology, precision machining and other fields, solve the problem that the measurement accuracy of existing photoelectric translational rotary encoder needs to be improved.Cameras are fixed on rotating or translating devices, and the encoding device of the encoder is fixed on a stationary frame.The encoding device of the encoder is composed of uniformly distributed encoding arrays and fine measurement spots.During the rotation or translation of the motion device, the camera captures the encoding array image and fine measurement spot image of the encoder.According to the encoding array image, the coarse-precision absolute position measurement value of the rotation angle is identified.According to the number of displacement pixels in the fine measurement spot image, the coarse-precision absolute position measurement value is subdivided to one-tenth of the total number of column pixels of the camera for measurement accuracy.According to the barycentric algorithm, the high-precision measurement value of the rotation angle or translation amount is calculated, which can significantly improve the photoelectric encoding measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of engineering measurement technology, and in particular to a novel photoelectric coding measurement method for a multi-level coarse and high precision translational and rotating platform. Background Technology

[0002] In many fields, such as precision instrument manufacturing, automation control, and aerospace, there are extremely high requirements for the angle measurement accuracy of rotating platforms. Currently, photoelectric rotary encoders, as commonly used sensors for rotation angle measurement, mainly include incremental encoders and absolute encoders. However, existing technologies have many limitations on improving measurement accuracy. Traditional measurement platforms rely on grating rulers, laser interferometers, or capacitive sensors to achieve multidimensional displacement and angle detection, but their performance is subject to multiple physical limitations: traditional photoelectric rotary encoders mostly use a method of engraving a grating code disk on a circular plane perpendicular to the motor axis. During motor operation, unavoidable vibrations will cause a certain amount of radial runout, which is very likely to cause a small displacement of the code track on the grating code disk. When the radial displacement reaches a certain amplitude, it will cause encoder reading errors, seriously affecting the accuracy of the measurement results. Furthermore, for circular grating encoder disks, existing technologies have difficulties in improving the moiré fringe subdivision accuracy. While higher magnification can be achieved by increasing the grating line density or the number of photosensitive elements, in practice, the current common grating line density is 50-100 lines within a 1mm range, and it is difficult to place multiple photosensitive elements while maintaining accurate phase difference. Furthermore, for absolute binary code disks, increasing the number of encoding bits is necessary to improve resolution, which not only greatly complicates the disk's manufacturing but also means that even minor manufacturing errors in binary code disks can lead to output signal errors.

[0003] Therefore, developing a novel high-precision photoelectric coding measurement method for multi-stage translation and rotation platforms that can effectively overcome the above problems has extremely important application value. Summary of the Invention

[0004] The purpose of this invention is to provide a novel multi-level coarse-to-high precision photoelectric coding measurement method for translational and rotary platforms, so as to solve the problem that the measurement accuracy of existing photoelectric rotary encoders needs to be improved.

[0005] This invention provides a novel multi-level coarse-to-high precision photoelectric coding measurement method for translational and rotating platforms, comprising:

[0006] Step 1: Acquire the coded array image and the precision measurement spot image; wherein, the camera is fixed on the rotating device or the translation device, and the encoder is fixed on the stationary frame. For the rotating measurement camera, the optical axis extension line passes through the rotation axis of the rotating device, and the central axis of the circular coded ring is coaxial with the rotation axis of the rotating device; for the translation measurement camera, it is fixed on the translation device, and the linear coded ruler is fixed on the stationary frame; the circular coded ring or the linear coded ruler consists of a uniformly distributed coded array and a precision measurement spot; during the rotation of the rotating device or the translation of the translation device, the camera acquires the coded array image and the precision measurement spot image of the circular coded ring or the linear coded ruler.

[0007] Step 2: Based on the encoded array image, identify the coarse-precision absolute position measurement value of the rotation angle or translation displacement;

[0008] Step 3: Based on the number of displacement pixels in the precision measurement spot image, the coarse-precision absolute position measurement value is subdivided to a measurement accuracy of one-tenth of the total number of pixels in the camera column. The rotation angle or translation displacement is calculated according to the centroid algorithm, and the distance resolution reaches 0.1 pixels, and the measurement accuracy reaches several times the measurement accuracy of one-tenth of the total number of pixels in the column.

[0009] Furthermore, the encoding array uses a preset base value of spectral colors for encoding; the circular encoding ring is divided into 360 evenly distributed parts; three-color LEDs are used as a group of light sources to form a light source group, and the color spectrum is set according to the requirements, and the color combination of each group of light sources in the circular encoding ring is planned according to the preset base value.

[0010] Furthermore, the encoding array encodes text characters with preset spacing, such as Arabic or other language characters, or patterns of different sizes and shapes.

[0011] Furthermore, the encoding array uses the size of the light spot for encoding; different sizes of light spots are encoded as transmitted light spots or diffuse reflection light spots, and the size of the light spot is calculated in the image captured by the camera to achieve encoding; using the combination of light spot sizes, the combination of light spots can be arbitrary base. In the decimal case, two light spots form 0 to 99, three light spots form 0 to 999, four light spots form 0 to 9999, and so on, to complete the encoding combination within the measurement range.

[0012] Furthermore, in step three, the calculation is performed according to the following formula:

[0013] sinθ=L0 / R

[0014] L0 = n * μ / M

[0015]

[0016] In the formula, n is the number of displacement pixels in the precision measurement spot image, μ is the pixel size, M is the optical magnification, θ is the rotation angle of the rotating device, R is the radius of the rotating device, and L0 is the image offset of the precision measurement spot of the circular coding ring at a radius of R when the rotating device rotates by an angle θ.

[0017] Furthermore, when n=1, R=100mm, μ=1 micrometer, and M=2, the angular resolution θ0 of one pixel is:

[0018]

[0019] θ0 = 1.03 seconds

[0020] Based on the total number of pixels n of the camera 总 =8000, calculate the angle range θ of a single image from the camera. 单幅量程 :

[0021] θ 单幅量程 =n 总 *θ0 = 8000 * 1.03 = 8250 seconds, which exceeds 2 degrees; let θ0 be... Derivation

[0022] Furthermore, the circular coding ring at the 0-mark position of the rotating device is set to 000, and the circular coding ring is sequentially spaced L apart. 粗刻度单幅量程 The rotation length is set to 001, 002, ..., 010, 011, ..., 098, 099, 100, 101, ..., 998, 999 for the circular encoding ring light source; the rotation angle is 2 degrees, corresponding to L. 粗刻度单幅量程 It is 3.49mm;

[0023] The absolute rotation angle of the rotating device is obtained from the encoded N of the camera image:

[0024]

[0025] In the formula, θ 绝对 denoted as the absolute rotation angle of the rotating device, N as the encoding of the circular-coded light source obtained from the camera image, n as the number of displacement pixels in the precision measurement spot image, μ as the pixel size, M as the optical magnification, and R as the radius of the rotating device.

[0026] Furthermore, in the total number of pixels n of the camera 总 =8000 pixels, each pixel at 1 arcsecond, the encoding calculation and switching method is as follows:

[0027] The N-1th coding group is designed to be 7200 pixels apart from the Nth coding group, corresponding to an angle of 2 degrees. First, the centroid of the left coding spot is calculated. If the number of pixels at the centroid of the left coding spot increases during movement, when the coordinates of the centroid of the left coding spot (nn)(N-1)0 When the number of pixels is less than 7200, the centroid calculation result of the left-side coded spot shall prevail:

[0028]

[0029] In the formula, (N-1) encoding group is N-1 coarse scale encoding data, and n is the centroid (pixel) value of the precision measurement spot in N-1 coarse scale encoding group; n (N-1)0 This refers to the pixel value of the centroid of the precision measurement spot in the N-1 code group (decimal base), which has an angle of 7200 pixels for the previous code group (N-2) during calibration. μ is the pixel size, M is the optical magnification, and R is the radius of the rotating device.

[0030] If the number of pixels at the centroid position of the light spot decreases during movement, and the initial value is greater than 7200, then when (N-1) the coordinates of the centroid of the encoded light spot (n (N-1)0 When -n) is less than 7200 pixels, the centroid calculation result of the left (N-1) encoded spot shall prevail:

[0031]

[0032] If the number of pixels at the centroid position of the light spot increases during movement, then the left (N-1) encoded light spot centroid coordinates (nn) (N-1)0 When the number of pixels is greater than 7200, switch to the right encoder N to encode the centroid coordinates of the light spot, and use the result of this encoding calculation. The calculation result is:

[0033]

[0034] n (N)0 For (nn) (N-1)0 When ) = 7200, the pixel value of the centroid of the precision measurement spot is obtained by using the right-hand encoding group N when using decimal carry.

[0035] If the number of pixels at the centroid position of the light spot decreases when moving, then the left (N-1) encoded light spot centroid coordinates (nn) (N-1)0 When the number of pixels is greater than 7200, switch to the right encoder N to encode the centroid coordinates of the light spot, and use the result of this encoding calculation. The calculation result is:

[0036]

[0037] n (N)0 For (n (N-1)0 When -n)=7200, the pixel value of the centroid of the precision measurement spot is obtained by using the right-hand encoding N groups when using decimal carry.

[0038] Furthermore, the method also includes:

[0039] Using the spot centroid algorithm, two fine measurement spots are designed, one above the other. By measuring the centroid of the fine measurement spots, the displacement of the centroids of the two fine measurement spots is analyzed to determine whether there is a vertical deviation in the rotation of the rotating device. If there is a vertical deviation, the deviation is corrected by the algorithm.

[0040] Furthermore, the circular coding ring is provided with at least two levels of coding array;

[0041] The first-level coding array has a spacing of 2mm, covering the entire field of view. The coding array achieves a coarse-precision positioning accuracy of 2mm for absolute displacement at this level. The number of light spot displacement pixels achieves a measurement accuracy of one-tenth of the total number of pixels in a 2mm camera column.

[0042] The spacing between the second-level coding arrays is 10 to 100 times that of the full field of view of the first level. The second-level coding array achieves coarse positioning accuracy of 10 to 100 times that of an absolute displacement of 2 mm. The number of light spot displacement pixels achieves a measurement accuracy of 10 to 100 times that of one-tenth of the total number of pixels in the camera's array, which is 2 mm.

[0043] This invention offers the following advantages: A novel multi-level coarse-to-high precision photoelectric coding measurement method for a translational and rotating platform. By changing the optical magnification, the coarse precision value is altered. Simultaneously, in image recognition, a spot centroid algorithm is used to measure the spot centroid with a precision of 0.1 pixels, allowing for the design of angle and displacement measurement systems with arbitrary precision as needed. This invention can use spectral colors to encode values ​​in any base, designing the number of bits to meet encoding requirements within the measurement range. Encoding can also be achieved using spot size, text, or patterns of different sizes and shapes. Given the limitations of camera measurement frequency, to improve measurement speed, this invention can also add multiple levels of cameras to achieve rapid encoding and recognition of large-range coarse scales, utilizing a multi-level large field of view to enhance measurement speed. Attached Figure Description

[0044] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the spectral colors of the present invention;

[0046] Figure 2 This is a schematic diagram of angle calculation according to the present invention;

[0047] Figure 3 This is a schematic diagram of the light-transmitting hole of the turntable in this invention;

[0048] Figure 4 This is the system logic diagram of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The technical solutions provided by various embodiments of this invention will be described in detail below with reference to the accompanying drawings.

[0050] Please see Figures 1 to 4 The present invention provides a novel photoelectric encoding measurement method for a multi-level coarse-to-high precision translation and rotation platform, comprising:

[0051] Step 1: Acquire the coded array image and the precision measurement spot image; wherein, the camera is fixed on the rotating device or the translation device, and the encoder is fixed on the stationary frame. For the rotating measurement camera, the optical axis extension line passes through the rotation axis of the rotating device, and the central axis of the circular coded ring is coaxial with the rotation axis of the rotating device; for the translation measurement camera, it is fixed on the translation device, and the linear coded ruler is fixed on the stationary frame; the circular coded ring or the linear coded ruler consists of a uniformly distributed coded array and a precision measurement spot; during the rotation of the rotating device or the translation of the translation device, the camera acquires the coded array image and the precision measurement spot image of the circular coded ring or the linear coded ruler.

[0052] Specifically, the camera rotates along with the rotating device. For example, within a rotating device with a design radius of 100mm, the camera's focal length and magnification are adjusted. The magnification is calculated according to design requirements. The effect is that within the camera's acquisition range, at most two sets of coded arrays will appear, used to calculate the coded range of the rotating device's movement. The coded arrays can use preset base values ​​of spectral colors for encoding; the circular coded ring is divided into 180 evenly distributed parts; three LEDs are used as a group of light sources to form a light source group. Based on the color spectrum, the color combination of each group of light sources in the circular coded ring is planned according to the decimal values ​​of the encoding. Alternatively, binary, quinary, and other base encoding methods can also be used.

[0053] Encoding arrays can also utilize text with preset spacing or patterns of different sizes and shapes for encoding. For example, text can be encoded using Arabic numerals 1, 2, or other characters such as Chinese or English to directly encode coarse scale values.

[0054] Encoding arrays can also utilize light spot size for encoding; by planning the size of the light-transmitting aperture on the rotating device facing the light source, the size of the light spot in the camera-captured image is controlled to achieve encoding; three LED light sources are grouped together, and the light spot sizes are combined to complete the encoding combination within the measurement range. The processing method for the translation platform is the same, except that the measurement is not on a rotating axis, but on a sliding axis that can be translated, with the light source arranged on it, and the encoding combination method is consistent with that of the rotating platform.

[0055] Based on the design measurement accuracy requirements and ease of understanding, a decimal encoding method is used to meet the encoding requirements, which can be used to achieve coarse scale position recognition measurement. Taking decimal as an example, the encoding rules are as follows: ten colors represent 0 to 9; different spot sizes represent 0 to 9; characters 0 to 9 represent 0 to 9; the coarse scale disk of the encoding array is distributed at the end of an arc with a radius R = 100 mm, and every coarse scale L... 粗刻度单幅量程 Set up a coding array, with a rotation angle of 2 degrees corresponding to L. 粗刻度单幅量程 The thickness is 3.49mm, which can be determined based on the number of camera pixels and the final angular resolution and accuracy. This coarse scale encoding array consists of three vertically arranged encoding points. This encoding is achieved by setting the color, spot size, or text of each encoding point from 0 to 9. This allows for coarse scale encoding from 000, 001, 002...999, achieving a translational encoding of 3.49 * 999 = 3486.51mm. A 360-degree rotation actually only requires 360 / 2 = 180 encoding arrays, i.e., encoding from 000 to 180.

[0056] Step 2: Based on the encoded array image, identify the coarse scale absolute position measurement value under coarse precision for rotation angle or translation displacement.

[0057] Reference Figure 2 The diagram shows the geometric principle of angle calculation. By using the known radius R of the rotating device and the image offset L0 of the fine measurement spot of the circular encoder ring at the radius R when the rotating device rotates by an angle θ calculated by the algorithm, the rotation angle θ of the rotating device can be calculated.

[0058] The principle of the translation platform is similar to that of the rotary platform. The difference is that the translation platform directly calculates the translation displacement by using a camera to encode the light spot during translation, identifying the coarse light spot encoding scale and the fine pixel offset L0, without having to calculate the angle to complete the measurement.

[0059] Step 3: Based on the number of displacement pixels in the precision measurement spot image, the coarse-precision absolute position measurement value is subdivided to a measurement accuracy of one-tenth of the total number of pixels in the camera column. The rotation angle or translation displacement is calculated according to the centroid algorithm, and the distance resolution reaches 0.1 pixels, and the measurement accuracy reaches several times the measurement accuracy of one-tenth of the total number of pixels in the column.

[0060] By utilizing the multi-pixel count and optical magnification of a high-resolution camera, angle measurements with arbitrary precision can be achieved. The calculation is performed according to the following formula:

[0061] sinθ=L0 / R

[0062] L0 = n * μ / M

[0063]

[0064] In the formula, n is the number of displacement pixels in the precision measurement spot image, μ is the pixel size, M is the optical magnification, θ is the rotation angle of the rotating device, R is the radius of the rotating device, and L0 is the image offset of the precision measurement spot of the circular coding ring at a radius of R when the rotating device rotates by an angle θ. According to the above formula, as long as the number of displacement pixels n in the precision measurement spot image is measured, the rotation angle θ of the rotating device can be calculated.

[0065] When n=1, R=100mm, μ=1 micrometer, and M=2, the angular resolution θ0 of one pixel is:

[0066]

[0067] θ0 = 1.03 seconds

[0068] Based on the total number of pixels n of the camera 总 =8000, calculate the angle range θ of a single image from the camera. 单幅量程 :

[0069] θ 单幅量程 =n 总 *θ0 = 8000 * 1.03 = 8250 seconds, exceeding 2 degrees; considering the size of the encoding array and the light spot, the measurement range will be designed to be smaller. Let θ0 be... Inverse derivation

[0070] Based on the above algorithm, the absolute rotation angle of the rotating device can be obtained. The circular coding ring at the 0-mark position of the rotating device is set to 000, and the circular coding ring is sequentially spaced L... 粗刻度单幅量程 The rotation length is set to 001, 002, ..., 010, 011, ..., 098, 099, 100, 101, ..., 998, 999 for the circular and ring encoding light sources; the rotation angle is 2 degrees, corresponding to L. 粗刻度单幅量程 It is 3.49mm.

[0071] Based on the code N obtained from the camera image, taking 025 as an example with a coarse scale of 50 degrees, the absolute rotation angle of the rotating device is obtained as follows:

[0072]

[0073] In the formula, θ 绝对 denoted as the absolute rotation angle of the rotating device, N as the encoding of the circular-coded light source obtained from the camera image, n as the number of displacement pixels in the precision measurement spot image, μ as the pixel size, M as the optical magnification, and R as the radius of the rotating device.

[0074] In the total number of pixels n of the camera 总 =8000 pixels, each pixel at 1 arcsecond, the encoding calculation and switching method is as follows:

[0075] The N-1th coding group is designed to be 7200 pixels apart from the Nth coding group, corresponding to an angle of 2 degrees. First, the centroid of the left coding spot is calculated. If the number of pixels at the centroid of the left coding spot increases during movement, when the coordinates of the centroid of the left coding spot (nn) (N-1)0 When the number of pixels is less than 7200, the centroid calculation result of the left-side coded spot shall prevail:

[0076]

[0077] In the formula, (N-1) encoding group is N-1 coarse-scale encoded data, and n is the pixel value of the centroid of the precision measurement spot in the N-1 coarse-scale encoding group; n (N-1)0 The pixel value of the centroid of the precision measurement spot of the N-1 encoding group when using decimal carry-over for the previous encoding group (N-2) with an angle of 7200 pixels during calibration. μ is the pixel size, M is the optical magnification, and R is the radius of the rotating device;

[0078] If the number of pixels at the centroid position of the light spot decreases during movement, and its initial value is greater than 7200, then when the (N-1) encoded light spot centroid coordinates (n (N-1)0 When -n) is less than 7200 pixels, the centroid calculation result of the left (N-1) encoded spot shall prevail:

[0079]

[0080] If the number of pixels at the centroid position of the light spot increases during movement, then the left (N-1) encoded light spot centroid coordinates (nn) (N-1)0 When the number of pixels is greater than 7200, switch to the right encoder N to encode the centroid coordinates of the light spot, and use the result of this encoding calculation. The calculation result is:

[0081]

[0082] n (N)0 For (nn) (N-1)0 When ) = 7200, the pixel value of the centroid of the precision measurement spot is obtained by using the right-hand encoding group N when using decimal carry.

[0083] If the number of pixels at the centroid position of the light spot decreases when moving, then the left (N-1) encoded light spot centroid coordinates (nn)(N-1)0 When the number of pixels is greater than 7200, switch to the right encoder N to encode the centroid coordinates of the light spot, and use the result of this encoding calculation. The calculation result is:

[0084]

[0085] n (N)0 For (n (N-1)0 When -n)=7200, the pixel value of the centroid of the precision measurement spot is obtained by using the right-hand encoding N groups when using decimal carry.

[0086] The measured rotation angle can be displayed in real time in the display area of ​​the rotating device. The measurement results can be output through the communication interface.

[0087] This invention can also accurately compensate for rotational offset. It utilizes a spot centroid algorithm to design two fine measurement spots, one above the other. By measuring the centroid of these fine measurement spots, the displacement of the centroids in the two spots is analyzed to determine if there is a vertical deviation in the rotation of the rotating device. If there is a vertical deviation, the algorithm corrects the deviation, thereby improving accuracy.

[0088] Given the measurement frequency limitations of cameras, this method can also incorporate multiple levels of cameras to achieve rapid encoding and recognition of large-range coarse scales in order to improve measurement speed. Multi-level large field-of-view angles are utilized to enhance measurement speed. The circular encoding ring is equipped with at least two levels of encoding arrays.

[0089] The first-level coding array has a spacing of 2mm, covering the entire field of view. The coding array achieves a coarse-precision positioning accuracy of 2mm for absolute displacement at this level. The number of light spot displacement pixels achieves a measurement accuracy of one-fifth of the total number of pixels in a 2mm camera column; for example, it can achieve a measurement accuracy of 0.25 micrometers, one-fifth of 8000 pixels.

[0090] The spacing between the second-level coding arrays is 10 to 100 times that of the first-level full field of view. The second-level coding array achieves coarse positioning accuracy of 10 to 100 times that of an absolute displacement of 2 mm; the number of light spot displacement pixels achieves a measurement accuracy of 10 to 100 times that of one-tenth of the total number of pixels in the camera's array, which is 2 mm. For example, taking 100x as an example, a measurement accuracy of 1 / 8000 pixels, or 25 micrometers, can be achieved.

[0091] If the measurement speed of rotation angle and translation displacement is to be further improved, a third-level coding array can be designed. The spacing of the coding array is 10 to 100 times that of the second-level full-view array, and the maximum can reach 20m. This can greatly improve the measurement speed.

[0092] The embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention.

Claims

1. A novel photoelectric coding measurement method for a multi-level coarse-to-high precision translational-rotation platform, characterized in that, include: Step 1: Acquire the coded array image and the precision measurement spot image; wherein, the camera is fixed on the rotating device or the translation device, and the encoder is fixed on the stationary frame. For the rotating measurement camera, the optical axis extension line passes through the rotation axis of the rotating device, and the central axis of the circular coded ring is coaxial with the rotation axis of the rotating device; for the translation measurement camera, it is fixed on the translation device, and the linear coded ruler is fixed on the stationary frame; the circular coded ring or the linear coded ruler consists of a uniformly distributed coded array and a precision measurement spot; during the rotation of the rotating device or the translation of the translation device, the camera acquires the coded array image and the precision measurement spot image of the circular coded ring or the linear coded ruler. Step 2: Based on the encoded array image, identify the coarse-precision absolute position measurement value of the rotation angle or translation displacement; Step 3: Based on the number of displacement pixels in the precision measurement spot image, the coarse-precision absolute position measurement value is subdivided to a measurement accuracy of one-tenth of the total number of pixels in the camera column. The rotation angle or translation displacement distance is calculated according to the centroid algorithm, and the resolution reaches 0.1 pixels, and the measurement accuracy reaches several times the measurement accuracy of one-tenth of the total number of pixels in the column. In step three, the calculation is performed according to the following formula: = = n m / M In the formula, n is the number of displacement pixels in the precision measurement spot image, μ is the pixel size, and M is the optical magnification. R is the rotation angle of the rotating device, and R is the radius of the rotating device. Rotate the rotating device The image shift of the fine measurement spot of the circular coding ring at a radius of R when the angle is measured; When n=1, R=100mm, μ=1 micrometer, and M=2, the angular resolution of 1 pixel is... for: 1.03 seconds Based on the total number of pixels in the camera =8000, calculate the angle range of a single image from the camera. : 1.03 = 8250 seconds, exceeding 2 degrees; take = Degree, derivation = 2.0626 times; The circular coding ring at the 0-mark position of the rotating device is set to 000, and the circular coding ring is sequentially set to 000 at intervals of... The rotation length is set to 001, 002, ... 010, 011, ... 098, 099, 100, 101 ... 998, 999 for the circular encoding ring light source; the rotation angle is 2 degrees, corresponding to... It is 3.49mm; The absolute rotation angle of the rotating device is obtained from the encoded N of the camera image: In the formula, The absolute rotation angle of the rotating device is given by , N is the code of the circular-coded and ring-coded light source obtained from the camera image, n is the number of displacement pixels in the precision measurement spot image, μ is the pixel size, M is the optical magnification, and R is the radius of the rotating device. Total number of pixels in the camera =8000 pixels, each pixel at 1 arcsecond, the encoding calculation and switching method is as follows: The N-1th coding group is designed to be 7200 pixels apart from the Nth coding group, corresponding to an angle of 2 degrees. First, the centroid of the left coding spot is calculated. If the number of pixels at the centroid position of the left coding spot increases during movement, then the coordinates of the left coding spot's centroid will be... When the number of pixels is less than 7200, the centroid calculation result of the left-side coded spot shall prevail: In the formula, N-1 coarse-scale encoded data, The pixel value of the centroid of the precision measurement spot for the N-1 coarse scale coding group; The pixel value of the centroid of the precision measurement spot of the N-1 code group with a decimal base of 7200 pixels in the previous code group (N-2) during calibration; μ is the pixel size, M is the optical magnification, and R is the radius of the rotating device. If the number of pixels at the centroid position of the light spot decreases during movement, and the initial value is greater than 7200, then when (N-1) encoded light spot centroid coordinates... When the number of pixels is less than 7200, the centroid calculation result of the left (N-1) coded spot shall be used: If the number of pixels at the centroid position of the light spot increases during movement, then the left (N-1) encoded light spot centroid coordinates When the number of pixels is greater than 7200, switch to the right encoder N-encoded spot centroid coordinates, and use the calculation result of this encoding as the standard; the calculation result is: for The pixel value of the centroid of the precision measurement spot when using the right-hand encoding N groups in decimal carry; If the number of pixels at the centroid position of the light spot decreases during movement, then the left (N-1) encoded light spot centroid coordinates When the number of pixels is greater than 7200, switch to the right encoder N-encoded spot centroid coordinates, and use the calculation result of this encoding as the standard; the calculation result is: for The right-hand side of the N-group is the pixel value of the centroid of the precision measurement spot.

2. The photoelectric encoding measurement method for a novel multi-stage coarse-to-high precision translational-rotation platform as described in claim 1, characterized in that, The encoding array uses a preset base value of spectral colors for encoding; the circular encoding ring is divided into 360 evenly distributed parts; three-color LEDs are used as a group of light sources to form a light source group, and the color spectrum is set according to the requirements. The color combination of each group of light sources in the circular encoding ring is planned according to the preset base value.

3. The photoelectric encoding measurement method for a novel multi-stage coarse-to-high precision translational-rotation platform as described in claim 1, characterized in that, The encoding array encodes text or patterns of different sizes and shapes with preset spacing.

4. The photoelectric encoding measurement method for a novel multi-stage coarse-to-high precision translational-rotation platform as described in claim 1, characterized in that, The encoding array uses the size of the light spot for encoding; different sizes of light spots are encoded as either transmitted light spots or diffuse reflection light spots. The size of the light spot is calculated in the image captured by the camera to achieve encoding; the combination of light spot sizes is used, and the combination of light spots can be arbitrary base. In the decimal case, two light spots form 0 to 99, three light spots form 0 to 999, four light spots form 0 to 9999, and so on, to complete the encoding combination within the measurement range.

5. The photoelectric encoding measurement method for a novel multi-stage coarse-to-high precision translational-rotation platform as described in claim 1, characterized in that, The method further includes: Using the spot centroid algorithm, two fine measurement spots are designed, one above the other. By measuring the centroid of the fine measurement spots, the displacement of the centroids of the two fine measurement spots is analyzed to determine whether there is a vertical deviation in the rotation of the rotating device. If there is a vertical deviation, the deviation is corrected by the algorithm.

6. The photoelectric encoding measurement method for a novel multi-stage coarse-to-high precision translational-rotation platform as described in claim 1, characterized in that, The circular coding ring is provided with at least two levels of coding array; The first-level coding array has a spacing of 2mm, covering the entire field of view. The coding array achieves a coarse-precision positioning accuracy of 2mm for absolute displacement at this level. The number of light spot displacement pixels achieves a measurement accuracy of one-tenth of the total number of pixels in a 2mm camera column. The spacing between the second-level coding arrays is 10 to 100 times that of the full field of view of the first level. The second-level coding array achieves coarse positioning accuracy of 10 to 100 times that of an absolute displacement of 2 mm. The number of light spot displacement pixels achieves a measurement accuracy of 10 to 100 times that of one-tenth of the total number of pixels in the camera's array, which is 2 mm.

Images