Monocular vision large-size revolving body diameter dynamic measurement device and method

Abstract

The invention discloses a monocular vision large-size rotary body diameter dynamic measurement device and method, when measurement is not carried out, a first triangular reflector and a second triangular reflector are respectively close to a spectroscope and a third triangular reflector, the reading of a grating ruler is 0, and a monocular linear array camera obtains initial single-frame linear array images of two paths of parallel light; during measurement, the mobile platform longitudinally moves along the ball screw and the sliding rail, the measured revolving body is placed in an area defined by the mobile platform, the ball screw and the sliding rail, and the measured revolving body shields part of parallel light A and part of parallel light B between the first triangular reflector and the second triangular reflector. And the monocular linear array camera obtains shielded single-frame linear array images of the two paths of parallel light, and the diameter of the measured rotary body is calculated based on the initial single-frame linear array image and the shielded single-frame linear array images. The device has the advantages of good installation robustness, simple structure, high measurement precision, good synchronization, dynamic detection, no need of repeated calibration and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of rotary body size measurement, and particularly relates to a monocular vision large-size rotary body diameter dynamic measurement device and method. Background Art

[0002] In the automotive, bearing and national defense industries, the on-line detection of large rotary workpieces has always been a problem affecting accuracy. Scholars at home and abroad have conducted a lot of research on the measurement of the diameter and related parameters of rotary parts.

[0003] At present, the diameter measurement of large rotary bodies is mainly divided into two categories: contact measurement and non-contact measurement. Among them, contact measurement generally uses large calipers and callipers to manually measure the large outer diameter after the workpiece is processed. The means are backward, the operation is inconvenient, the efficiency is low, the accuracy is not high, the continuous measurement of the rotary body cannot be carried out, and the human factor has a great influence. Non-contact detection mainly includes laser sensor detection and machine vision detection. Laser measurement uses a dual-sensor distributed method, and the calibration solution is a split-type solution using two laser sensors. Before each use of the split-type detection device, a standard block of the same size as the measured rotary body needs to be used for calibration, and the synchronization of the two sensors is poor. The data collected by the two sensors are compared to obtain the diameter of the rotary body. The operation is complex, vulnerable to interference, and the accuracy is poor. Visual measurement uses a diameter measurement system constructed based on the principle of pinhole imaging. By calculating the backlight edge of the measured cylinder, the diameter measurement of cylindrical workpieces is realized. Its measurement accuracy is affected by factors such as the position of the measured workpiece and the quality of the collected image, and due to the resolution of the sensor, the measurement accuracy is low.

[0004] Mechanical displacement is the position change of a mechanical object in a certain direction. In mechanical motion, the axis of rotation deviates from the ideal position and there is a deviation. For this deviation, it is necessary to measure its displacement for index evaluation. Radial end play is a manifestation of displacement and is one of the most commonly used in mechanical quantity measurement. In the actual production process, it is necessary to monitor the radial end play of a high-speed rotating shaft so as to control the radial end play of the shaft within a predetermined range. Summary of the Invention

[0005] The purpose of the invention is to solve the deficiencies existing in the prior art, and provides a monocular vision large-size rotary body diameter dynamic measurement device and method, which solves the problems of complex operation and low accuracy in the existing rotary body diameter measurement process.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A monocular vision large-size rotary body diameter dynamic measurement device, comprising a parallel line light source, a beam splitter, a first triangular reflector, a second triangular reflector, a third triangular reflector, a monocular line array camera, a fixing device, a servo motor, a ball screw, a moving platform, a slide rail and a grating scale. The ball screw and the slide rail are respectively fixed on the left and right sides of the fixing device. The ball screw and the slide rail are longitudinally parallel and transversely arranged. One end of the horizontally arranged moving platform is connected to the nut of the ball screw, and the other end is slidably connected to the slide rail. The output shaft of the servo motor is connected to the screw rod of the ball screw. The parallel line light source is fixed on one side of the servo motor. The beam splitter is fixed behind the parallel line light source. The first triangular reflector and the second triangular reflector are respectively fixed at the left and right ends of the moving platform. The monocular line array camera is fixed at the front end of the slide rail. The third triangular reflector is arranged on one side of the monocular line array camera. The parallel line light source emits parallel line light, which is divided into two beams of parallel line light in the orthogonal direction by the beam splitter. One beam of parallel light A is the 90° reflected light of the beam splitter, and the other beam of parallel light B is the transmitted light of the beam splitter. The parallel light A directly enters the monocular line array camera. The parallel light B is reflected by the first triangular reflector, the second triangular reflector and the third triangular reflector in sequence and finally enters the monocular line array camera. The grating scale is used to obtain the distance between the beam splitter and the first triangular reflector.

[0007] The grating scale includes a scale grating and an indicating grating that cooperate with each other. The scale grating is fixed along the length direction of the ball screw, and the indicating grating is fixed at one end of the moving platform close to the scale grating.

[0008] Specifically, a monocular vision large-size rotary body diameter dynamic measurement device involved in the present invention further includes a first slide bar, a second slide bar, a first fixing block, a first slider, a second fixing block and a second slider. The first slide bar is arranged above the ball screw, and the second slide bar is arranged above the slide rail. The first slide bar and the second slide bar are parallel. One end of the first slide bar is fixed on the first fixing block, and the other end of the first slide bar passes through the through hole on the first slider and the first slider slides along the first slide bar. The beam splitter is fixed on the first fixing block, and the first triangular reflector is fixed on the first slider. One end of the second slide bar is fixed on the second fixing block, and the other end of the second slide bar passes through the through hole on the second slider and the second slider slides along the second slide bar. The second triangular reflector is fixed on the second slider, and the third triangular reflector is fixed on the second fixing block.

[0009] Specifically, the fixing device is a mechanical frame with a longitudinal length of H and a transverse width of L, where L > H. The diameter measurement range of the measured rotary body is S~H.

[0010] Further, a method for dynamically measuring the diameter of a large-sized rotary body using monocular vision according to the present invention further includes a turntable and an encoder. The rotary body to be measured is fixed on the turntable, and the encoder is arranged on the turntable. The turntable drives the rotary body to be measured to rotate, and the encoder is used to measure the rotation angle of the rotary body. Based on the diameter and the rotation angle, the outer contour of the rotary body to be measured can be determined.

[0011] Specifically, based on the diameter, the radial end jump of the rotary body to be measured can be detected.

[0012] The specific measurement method of a device for dynamically measuring the diameter of a large-sized rotary body using monocular vision according to the present invention includes the following steps: (1) Calibration: First, without placing the rotary body to be measured, move the platform close to the beam splitter. At this time, the reading of the grating scale is 0. The parallel light A is directly incident on the monocular linear array camera, and the parallel light B is reflected successively by the first triangular mirror, the second triangular mirror, and the third triangular mirror, and finally incident on the monocular linear array camera. The two beams of light form two light bands in the linear array camera. The monocular linear array camera obtains an initial single-frame linear array image containing two parallel light bands, removes the background and noise of the initial single-frame linear array image, and extracts the edge column coordinates P 0 1, P 0 2, P 0 3, P 0 4. Calculate the distance S between the two parallel light bands A and B and the sum W of the widths of the two parallel light bands A and B when the rotary body to be measured is not placed. S = P 0 3 – P 0 2, W = P 0 4 - P 0 1 - S.

[0013] Specifically, (101) The background and noise of the initial single-frame linear array image are removed by the threshold method, and only the information of the parallel light bands is retained.

[0014] (2)

[0015] In the formula, is the gray value of the initial single-frame linear array image after removing the background and noise, threshold is the threshold for background removal, is the gray value of the initial single-frame linear array image.

[0016] (102) Adopt a local edge search algorithm to obtain the four edge column coordinates P of the parallel light bands in the initial single-frame linear array image processed in step (101) 0 1, P 0 2, P 0 3, P 0 4. Calculate the distance S between the two parallel light bands A and B and the sum W of the widths of the two parallel light bands A and B when the rotary body to be measured is not placed.

[0017] (2) Single diameter measurement: The moving platform moves, and the rotating body to be measured is placed in the area enclosed by the moving platform, the ball screw, and the slide rail. The rotating body to be measured blocks part of the parallel light A and part of the parallel light B between the first triangular reflector and the second triangular reflector. The reading of the grating scale is G. The two blocked light beams also form two light bands in the linear array camera. The monocular linear array camera obtains a single-frame linear array image with two parallel light bands after occlusion. Remove the background and noise of the single-frame linear array image after occlusion, and use the bilateral centroid method to extract the edge column coordinates P 1 1, P 1 2, P 1 3, P 1 4, Calculate the width T1 of the parallel light A and the width T2 of the parallel light band B after placing the rotating body to be measured and blocking. T1 = P 1 2 - P 1 1, T2 = P 1 4 - P 1 3, T = T1 + T2, and calculate the diameter D of the rotating body to be measured according to the following formula.

[0018]

[0019] Specifically, (201) Use the threshold method to remove the background and noise of the single-frame linear array image after occlusion, and only retain the information of the parallel light bands.

[0020]

[0021] In the formula, is the gray value of the single-frame linear array image after occlusion with the background and noise removed, threshold is the threshold for background removal, is the gray value of the single-frame linear array image after occlusion.

[0022] (202) The linear array camera uses a lensless imaging method, which does not conform to the point spread model. The incident light is parallel light. Therefore, the black and white transition of the edge pixels does not conform to the Gaussian distribution, and the Gaussian fitting method cannot be used to obtain the sub-pixel coordinates. The present invention uses the bilateral centroid method to identify the transition center of the edge and uses the bilateral centroid method to extract the edge column coordinates P 1 2, P 1 3, and P 1 1 = P 0 1, P 1 4 = P 0 4.

[0023]

[0024] Among them, Lc is the central coordinate of the dark area between the two parallel light bands, mis the column coordinate for each row, is the gray value of the m-th column coordinate (pixel) after the processing in step (201), P 1 1, P 1 2, P 1 3, and P 1 4 are the edge column coordinates of the parallel light band in the single-frame linear array image after occlusion.

[0025] (3) Measurement of the diameter in one revolution: The measured rotating body is fixed on the turntable. The turntable drives the measured rotating body to rotate one revolution. The monocular linear array camera collects the spatio-temporal image of the measured rotating body rotating one revolution in real time. Each frame image in the spatio-temporal image is a row, which is a single-frame linear array image. According to step (2), calculate the diameter corresponding to each row of the single-frame linear array image, and then obtain the diameter of the measured rotating body in one revolution.

[0026] Furthermore, based on the diameter obtained in step (2) or (3), the radial runout of the measured rotating body can be detected.

[0027] Furthermore, based on the diameter of the rotating body in one revolution obtained in step (3) and the rotation angle of the rotating body, the outer contour of the measured rotating body can be determined.

[0028] The present invention provides a monocular vision large-size rotating body diameter measuring device that can solve the problems of large range, high precision, simple operation, and improve the real-time performance of the image processing algorithm.

[0029] The beneficial effects of the present invention are as follows: (1) It overcomes the deficiencies of the traditional method that requires multiple sensors and measurement accuracy problems. The monocular linear array camera receives the linear parallel light emitted by the same light source, and has good synchronization. According to the widths of the two parallel light bands obtained by the linear array camera and combined with the reading of the grating scale, the sub-pixel-level shaft diameter can be obtained, improving the detection accuracy; (2) Only need to perform initial calibration of the device with a standard diameter at the factory, without repeated calibration; (3) The linear array camera has a high frame rate. By using optical and image processing methods, using linear parallel light combined with an absolute grating as a reference, real-time dynamic measurement of the diameter, radial runout, and outer contour of a large rotating body can be achieved; (4) The mechanical movement accuracy requirements for the servo motor are low. Since the diameter of the rotating body is superimposed by the grating scale and the pixels of the linear array camera, and the parallel light band has a width, as long as the movement can cover the rotating body, the repeated coverage area does not affect the calculation of the rotating body diameter; (5) During measurement, only the rotating body needs to block the parallel light, without strict control of the position. The horizontal width L of the fixed device > the vertical length H, effectively preventing the parallel light between the second triangular mirror and the third triangular mirror from being blocked, and having high robustness. Description of the Drawings

[0030] Figure 1 is the axonometric view of the monocular vision large-size rotating body diameter dynamic measuring device involved in the present invention.

[0031] Figure 2 It is the top view of the monocular vision large-size rotary body diameter dynamic measurement device involved in the present invention.

[0032] Figure 3 It is the flowchart of the monocular vision large-size rotary body diameter dynamic measurement method involved in the present invention.

[0033] Figure 4 They are single-frame linear array images before and after the threshold method processing of the present invention. Among them, Figure 4 a in it is the single-frame linear array image before processing, Figure 4 b in it is the single-frame linear array image after processing.

[0034] Figure 5 It is the schematic diagram of the principle of the monocular vision large-size rotary body diameter dynamic measurement method of the present invention. Among them, Figure 5 a in it is the schematic diagram of the principle of single-diameter measurement in step (2), Figure 5 b in it is the initial single-frame linear array image obtained in step (1).

[0035] In the figure: 1 is a parallel light source; 2 is a beam splitter; 3 is a first triangular reflector; 4 is a second triangular reflector; 5 is a third triangular reflector; 6 is a monocular linear array camera; 7 is a fixing device; 8 is a servo motor; 9 is a ball screw; 10 is a moving platform; 11 is a slide rail; 12 is a grating scale; 13 is a first slide bar; 14 is a second slide bar; 15 is a first fixing block; 16 is a first slider; 17 is a second fixing block; 18 is a second slider; 1201 is a scale grating; 1202 is an indicating grating; A is parallel light A; B is parallel light B. Detailed implementation manners

[0036] To make the objectives, technical solutions and advantages of the present invention clearer, the following further explains a kind of the present invention in combination with the attached drawings and specific examples.

[0037] Embodiment

[0038] As Figure 1 and 2As shown in the figure, a monocular vision dynamic measurement device for the diameter of a large-sized rotating body according to this embodiment includes a parallel light source 1, a beam splitter 2, a first triangular mirror 3, a second triangular mirror 4, a third triangular mirror 5, a monocular linear array camera 6, a fixing device 7, a servo motor 8, a ball screw 9, a moving platform 10, a slide rail 11 and a grating scale 12. The ball screw 9 and the slide rail 11 are respectively fixed on the left and right sides of the fixing device 7. The ball screw 9 and the slide rail 11 are longitudinally parallel. One end of the horizontally arranged moving platform 10 is connected to the nut of the ball screw 9, and the other end is slidably connected to the slide rail 11. The output shaft of the servo motor 8 is connected to the screw of the ball screw 9. The parallel light source 1 is fixed on one side of the servo motor 8. The beam splitter 2 is fixed behind the parallel light source 1. The first triangular mirror 3 and the second triangular mirror 4 are respectively fixed at the left and right ends of the moving platform 10. The monocular linear array camera 6 is fixed at the front end of the slide rail 11. The third triangular mirror 5 is arranged on one side of the monocular linear array camera 6. The parallel light source 1 emits parallel light. After passing through the beam splitter 2, it is divided into two beams of parallel light in orthogonal directions. One beam of parallel light A is the 90° reflected light (horizontal) of the beam splitter 2, and the other beam of parallel light B is the transmitted light (longitudinal) of the beam splitter 2. The parallel light A is directly incident on the monocular linear array camera. The parallel light B is reflected by the first triangular mirror 3, the second triangular mirror 4 and the third triangular mirror 5 in sequence, and finally is incident on the monocular linear array camera. The grating scale 12 includes a matching scale grating (main grating) 1201 and an indicating grating (sub-grating) 1202. The scale grating 1201 is fixed along the length direction of the ball screw 9. The indicating grating 1202 is fixed at one end of the moving platform 10 close to the scale grating 1201. The grating scale 12 is used to obtain the distance between the beam splitter 2 and the first triangular mirror 3.

[0039] For the monocular vision dynamic measurement device for the diameter of a large-sized rotating body according to this embodiment, when not measuring, the first triangular mirror 3 and the second triangular mirror 4 are respectively close to the beam splitter 2 and the third triangular mirror 5. The reading of the grating scale 12 is 0, and the monocular linear array camera 6 obtains the initial single-frame linear array images of the two beams of parallel light. When measuring, driven by the servo motor 8, the moving platform 10 moves longitudinally along the ball screw 9 and the slide rail 11. The measured rotating body is placed in the area surrounded by the moving platform 10, the ball screw 9 and the slide rail 11. And the measured rotating body blocks part of the parallel light A and part of the parallel light B between the first triangular mirror 3 and the second triangular mirror 4. The monocular linear array camera 6 obtains the single-frame linear array images of the two beams of parallel light after occlusion. The diameter of the measured rotating body is calculated based on the initial single-frame linear array image and the single-frame linear array image after occlusion.

[0040] The parallel light source 1, the beam splitter 2, the first triangular mirror 3, the second triangular mirror 4, the third triangular mirror 5 and the monocular linear array camera 6 involved in this embodiment constitute an optical module.

[0041] The fixing device 7, servo motor 8, ball screw 9, moving platform 10, slide rail 11, slider, and grating scale 12 involved in this embodiment constitute a mechanical module.

[0042] The first triangular reflector 3, second triangular reflector 4, and third triangular reflector 5 involved in this embodiment constitute a triangular reflector module.

[0043] Specifically, a monocular vision large-size rotating body diameter dynamic measurement device involved in this embodiment further includes a first slide bar 13, second slide bar 14, first fixing block 15, first slider 16, second fixing block 17, and second slider 18. The first slide bar 13 is arranged above the ball screw 9, the second slide bar 14 is arranged above the slide rail 11, the first slide bar 13 and the second slide bar 14 are arranged in parallel. One end of the first slide bar 13 is fixed on the first fixing block 15, the other end of the first slide bar 13 passes through the through hole on the first slider 16 and the first slider 16 slides along the first slide bar 13. The beam splitter 2 is fixed on the first fixing block 15, the first triangular reflector 3 is fixed on the first slider 16. One end of the second slide bar 14 is fixed on the second fixing block 17, the other end of the second slide bar 14 passes through the through hole on the second slider 18 and the second slider 18 slides along the second slide bar 14. The second triangular reflector 4 is fixed on the second slider 18, and the third triangular reflector 5 is fixed on the second fixing block 17. This structure can improve the coaxiality among the beam splitter 2, the first triangular reflector 3, the second triangular reflector 4, and the third triangular reflector 5, reduce the influence of the movement of the moving platform 10 on the optical path structure through which the parallel light B passes, and improve the detection accuracy.

[0044] Specifically, the beam splitter 2 is a BS beam splitter 2.

[0045] Specifically, the grating scale 12 is an absolute grating scale.

[0046] Specifically, the fixing device 7 is a mechanical frame with a longitudinal length of H and a transverse width of L, where L > H, which can prevent the parallel light between the second triangular reflector 4 and the third triangular reflector 5 from being blocked. The diameter measurement range of the measured rotating body is S to H. For example, S is 10 mm and H can reach 1000 mm. The measurement range is from 10 to 1000 mm. On the premise of ensuring the measurement accuracy, it can measure both small diameters and large diameters.

[0047] Further, a monocular vision large-size rotating body diameter dynamic measurement device involved in the embodiment further includes a turntable and an encoder. The measured rotating body is fixed on the turntable, an encoder is arranged on the turntable, the turntable drives the measured rotating body to rotate, and the encoder is used to measure the rotation angle of the rotating body. Based on the diameter and the rotation angle, the outer contour of the measured rotating body can be determined.

[0048] Such as Figure 3As shown in the figure, a method for dynamically measuring the diameter of a large-sized rotating body using monocular vision according to this embodiment includes the following steps.

[0049] (1) Calibration: First, without placing the rotating body to be measured, move the platform 10 close to the beam splitter 2. At this time, the reading of the grating scale 12 is 0. The parallel light A is directly incident on the monocular linear array camera 6, and the parallel light B is reflected successively by the first triangular mirror 3, the second triangular mirror 4, and the third triangular mirror 5, and finally incident on the monocular linear array camera 6. The two beams of light (parallel light A and parallel light B) form two light bands in the linear array camera. The monocular linear array camera 6 obtains an initial single-frame linear array image containing two parallel light bands ( Figure 5 the light bands in b in the figure), remove the background and noise of the initial single-frame linear array image, and extract the column coordinates P 0 1, P 0 2, P 0 3, P 0 4, where P 0 1 and P 0 2 are respectively the column coordinates of the left and right edges of the light band formed by the parallel light A in the initial single-frame linear array image, and P 0 3 and P 0 4 are respectively the column coordinates of the left and right edges of the light band formed by the parallel light B in the initial single-frame linear array image. Calculate the distance S between the two parallel light bands A and B and the sum of the widths W of the two parallel light bands A and B when the rotating body to be measured is not placed. S = P 0 3 – P 0 2, W = P 0 4 - P 0 1 - S, W = W1 + W2, where W1 is the width of the parallel light band A and W2 is the width of the parallel light band B.

[0050] Specifically, (101) use the threshold method to remove the background and noise of the initial single-frame linear array image and only retain the information of the parallel light bands.

[0051] (2)

[0052] In the formula, is the gray value of the initial single-frame linear array image after removing the background and noise, and threshold is the threshold for background removal. For example, threshold = mean(gray) + 5, and mean(gray) is the average gray value of the background area between the parallel light bands. is the gray value of the initial single-frame linear array image. Figure 4 is the single-frame linear array image before and after the threshold method processing of the present invention, where Figure 4Among them, a is the single-frame linear array image before processing, Figure 4 Among them, b is the single-frame linear array image after processing. It can be found that two clear light bands can be obtained after threshold processing.

[0053] (102)Adopt the local edge search algorithm to obtain the four edge column coordinates P of the parallel light bands of the initial single-frame linear array image after the processing in step (101) 0 1, P 0 2, P 0 3, P 0 4. Calculate the distance S between the two parallel light bands A and B, and the sum W of the widths of the two parallel light bands A and B when the measured rotating body is not placed.

[0054] During calibration, there may be a fluctuation of one pixel at the edge, so the local edge search is used to find the edge coordinates. As Figure 5 shown in b, when the initial single-frame linear array image is placed horizontally, the specific local edge search algorithm is as follows: in the first step, starting from the left side of the initial single-frame linear array image collected by the monocular linear array camera, search to the right for the first edge pixel point of the parallel light band with a gray value step, and search down to judge that it is a step point. The column coordinate of this pixel point is P 0 1 ; in the second step, starting from the center of the initial single-frame linear array image, search to the left for the first edge pixel point of the parallel light band with a gray value step, and search down to judge that it is a step point. The column coordinate of this pixel point is P 0 2 ; in the third step, starting from the center of the initial single-frame linear array image, search to the right for the first edge pixel point of the parallel light band with a gray value step, and search down to judge that it is a step point. The column coordinate of this pixel point is P 0 3 ; starting from the right side of the initial single-frame linear array image collected by the linear array camera, search to the left for the first edge pixel point of the parallel light band with a gray value step, and search down to judge that it is a step point. The column coordinate of this pixel point is P 0 4 .

[0055] (2)Single diameter measurement: The moving platform 10 moves, and the measured rotating body is placed in the area surrounded by the moving platform 10, the ball screw 9 and the slide rail 11, and the measured rotating body blocks part of the parallel light A ( Figure 5 in a X 1 part), and blocks part of the parallel light B between the first triangular reflector 3 and the second triangular reflector 4 ( Figure 5 in a X 2Part), the reading of the grating scale 12 is G. After being blocked, the two beams of light (parallel light A and parallel light B) also form two light bands in the linear array camera. The monocular linear array camera 6 obtains a single-frame linear array image with two parallel light bands after occlusion ( Figure 5 the upper light band in a), remove the background and noise of the single-frame linear array image after removing the occlusion, and use the bilateral centroid method to extract the column coordinates P of the edges of the parallel light bands in the single-frame linear array image after occlusion 1 1, P 1 2, P 1 3, P 1 4， Among them, P 1 1 and P 1 2 are respectively the column coordinates of the left and right edges of the light band formed by parallel light A in the single-frame linear array image after occlusion. P 1 3 and P 1 4 are respectively the column coordinates of the left and right edges of the light band formed by parallel light B in the single-frame linear array image after occlusion. Calculate the width T1 of parallel light A and the width T2 of parallel light band B after placing the measured rotating body. T1 = P 1 2 - P 1 1, T2 = P 1 4 - P 1 3, T = T1 + T2. According to the following formula, calculate the diameter D of the measured rotating body

[0056] Figure 5 The light band in b) is the initial single-frame linear array image containing two parallel light bands obtained by the monocular linear array camera 6 when the reading of the grating scale 12 is 0 without placing the measured rotating body Figure 5 The lower light band in a) is the single-frame linear array image obtained by the monocular linear array camera 6 when the reading of the grating scale 12 is G and the rotating body is not placed. Since in both cases, the two parallel light beams are not blocked, the width of the strip formed by parallel light A in the monocular linear array camera 6, and the width of the strip formed by parallel light B reflected by the first triangular mirror 3, the second triangular mirror 4 and the third triangular mirror 5 in the monocular linear array camera 6 are the same. Also, since the positions of the third triangular mirror 5 and the beam splitter 2 remain unchanged, the width between parallel light A and B when entering the monocular linear array camera 6 is the same, that is, the distance between the two strips is the same. Therefore Figure 5 The lower single-frame linear array image in a) is the same as the initial single-frame linear array image, that is, the four edge column coordinates P 0 1 , P 0 2 , P 03 , P 0 4 , W1 and W2 are the same. Since the actual distance represented by the distance between the two parallel strips is the distance between the beam splitter 2 and the first triangular reflector 3, and this distance is measured by the grating scale 12, Figure 5 the actual distance represented by the distance between the two parallel strips in b of Figure 5 is S (the reading of the grating scale 12 is 0), Figure 5 the actual distance represented by the distance between the two lower parallel strips in a of Figure 5 is S + G (the reading of the grating scale 12 is G). Since Figure 5 the lower light strip in a of Figure 5 and Figure 5 the light strip in b of Figure 5 have the same structure and are not measured during the actual measurement process. Here, it is only for explaining the principle of the present invention.

[0057] Specifically, (201) uses the threshold method to remove the background and noise of the single-frame linear array image after occlusion, and only retains the information of the parallel light strips:

[0058]

[0059] In the formula, is the gray value of the single-frame linear array image after removing the background and noise of the occlusion, threshold is the threshold for background removal, is the gray value of the single-frame linear array image after occlusion.

[0060] (202) The linear array camera adopts a lensless imaging method, which does not conform to the point spread model. The incident light is parallel light. Therefore, the black-and-white transition of the edge pixels does not conform to the Gaussian distribution, and the Gaussian fitting method cannot be used to obtain the sub-pixel coordinates. The present invention uses the bilateral centroid method to identify the transition center of the edge and uses the bilateral centroid method to extract the column coordinates P 1 2, P 1 3, and P 1 1 = P 0 1, P 1 4 = P 0 4.

[0061]

[0062] Among them, Lc is the central column coordinate of the dark area between the two parallel light strips, m is the column coordinate in each row, is the gray value of the m-th column coordinate (pixel) after the processing in step (201).

[0063] (3) One-week diameter measurement: The rotating body to be measured is fixed on the turntable. The turntable drives the rotating body to be measured to rotate one week. The monocular linear array camera collects the spatio-temporal images of the rotating body to be measured rotating one week in real time. Each frame (row) of the spatio-temporal image is a single-frame linear array image. According to step (2), the diameter corresponding to each frame (row) of the single-frame linear array image can be calculated, and then the diameter of the rotating body to be measured for one week can be obtained.

[0064] Specifically, the rotating body to be measured rotates. The single-frame linear array images obtained on the monocular linear array camera 6 are arranged frame by frame in the time acquisition order to form a spatio-temporal image. Each frame of the spatio-temporal image is a row and is a single-frame linear array image. The horizontal and vertical coordinates of the spatio-temporal image represent space and time respectively. The single-frame linear array image is a one-dimensional image. The horizontal resolution is the spatial resolution, and the vertical resolution depends on the speed of the rotating body to be measured and the frame frequency of the linear array camera, which is the time resolution. Mainly according to the change of the angular velocity of the rotating body to be measured, the monocular linear array camera collects the spatio-temporal images of the rotating body to be measured rotating one week in real time. According to step (2), each frame of the single-frame linear array image of the spatio-temporal image is processed to obtain the diameter of the rotating body to be measured for one week.

[0065] In step (3), first, the threshold method is used to remove the background and noise of each row of the single-frame linear array image in the spatio-temporal image, and then the bilateral centroid method is used to extract the column coordinates of the light band edge of each row of the single-frame linear array image after removing the background and noise. P i 2 , P i 3 , and P i 1 = P 0 1 , P i 4 = P 0 4 .

[0066]

[0067] Among them, Lc is the central column coordinate of the dark area between two parallel light bands. m is the column coordinate in each row. is the gray value of the coordinate (pixel) of the m-th column in the i-th row of the spatio-temporal image after removing the background and noise. Among them, P i 1 and P i 2 are respectively the column coordinates of the left and right edges of the light band formed by the parallel light A in the single-frame linear array image of the i-th row in the spatio-temporal image, Pi 3 and P i 4 are respectively the column coordinates of the left and right edges of the light band formed by the parallel light B in the single-frame linear array image of the i-th row in the spatio-temporal image, P i 1 = P 0 1 , P i 4 = P 0 4 。

[0068] Furthermore, based on the diameter obtained in step (2) or (3), the radial end run of the measured rotary body can be detected.

[0069] Furthermore, based on the diameter of the rotary body obtained in step (3) and the rotation angle of the rotary body, the outer contour of the measured rotary body can be determined Of course, the above content is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of the embodiments of the present invention. The present invention is not limited to the above examples either. Equivalent changes and improvements made by those of ordinary skill in the art within the essence of the present invention shall fall within the scope covered by the patent of the present invention.

Claims

1. A monocular vision dynamic measurement device for the diameter of a large-sized rotating body, characterized in that, It includes a parallel line light source, a beam splitter, a first triangular mirror, a second triangular mirror, a third triangular mirror, a monocular line array camera, a fixing device, a servo motor, a ball screw, a moving platform, a slide rail and a grating scale. The ball screw and the slide rail are respectively fixed on the left and right sides of the fixing device. The ball screw and the slide rail are longitudinally parallel. One end of the horizontally arranged moving platform is connected to the nut of the ball screw, and the other end is slidably connected to the slide rail. The output shaft of the servo motor is connected to the screw of the ball screw. The parallel line light source is fixed on one side of the servo motor. The beam splitter is fixed behind the parallel line light source. The first triangular mirror and the second triangular mirror are respectively fixed at the left and right ends of the moving platform. The monocular line array camera is fixed at the front end of the slide rail. The third triangular mirror is arranged on one side of the monocular line array camera. The parallel line light source emits parallel line light, which is divided into two beams of parallel line light in the orthogonal direction by the beam splitter. One beam of parallel light A is the 90° reflected light of the beam splitter, and the other beam of parallel light B is the transmitted light of the beam splitter. The parallel light A directly enters the monocular line array camera. The parallel light B is reflected by the first triangular mirror, the second triangular mirror and the third triangular mirror in sequence, and finally enters the monocular line array camera. The grating scale is used to obtain the distance between the beam splitter and the first triangular mirror.

2. The monocular vision large-size rotary body diameter dynamic measurement device according to claim 1, characterized in that, The grating scale includes a scale grating and an indicating grating that cooperate with each other. The scale grating is fixed along the length direction of the ball screw, and the indicating grating is fixed at one end of the moving platform close to the scale grating.

3. The monocular vision large-size rotating body diameter dynamic measurement device according to claim 1, characterized in that, It also includes a first slide bar, a second slide bar, a first fixing block, a first slider, a second fixing block and a second slider. The first slide bar is arranged above the ball screw, and the second slide bar is arranged above the slide rail. The first slide bar and the second slide bar are parallel. One end of the first slide bar is fixed on the first fixing block, and the other end of the first slide bar passes through the through hole on the first slider and the first slider slides along the first slide bar. The beam splitter is fixed on the first fixing block, and the first triangular mirror is fixed on the first slider. One end of the second slide bar is fixed on the second fixing block, and the other end of the second slide bar passes through the through hole on the second slider and the second slider slides along the second slide bar. The second triangular mirror is fixed on the second slider, and the third triangular mirror is fixed on the second fixing block.

4. The monocular vision large-size rotary body diameter dynamic measurement device according to claim 1, characterized in that, The fixing device is a mechanical frame with a longitudinal length of H and a transverse width of L, where L > H. The diameter measurement range of the measured rotating body is S~H.

5. The monocular vision large-size rotary body diameter dynamic measurement device according to claim 1, characterized in that It also includes a turntable and an encoder. The measured rotating body is fixed on the turntable, and the encoder is arranged on the turntable. The turntable drives the measured rotating body to rotate, and the encoder is used to measure the rotation angle of the rotating body. Based on the diameter and the rotation angle, the outer contour of the measured rotating body can be determined.

6. A dynamic measurement method for the diameter of a large-sized rotating body using monocular vision, characterized in that, Using the device described in claim 1 for measurement, it includes the following steps: (1)Calibration: First, without placing the rotating body to be measured, move the platform close to the beam splitter. At this time, the reading of the grating scale is 0. Parallel light A directly enters the monocular linear array camera, and parallel light B is reflected successively by the first triangular mirror, the second triangular mirror, and the third triangular mirror, and finally enters the monocular linear array camera. The two beams of light form two light bands in the linear array camera. The monocular linear array camera obtains an initial single-frame linear array image containing two parallel light bands, removes the background and noise of the initial single-frame linear array image, and extracts the column coordinates of the edges of the parallel light bands. P 0 1 , P 0 2 , P 0 3 , P 0 4 , where P 0 1 and P 0 2 are the column coordinates of the left and right edges of the light band formed by parallel light A in the initial single-frame linear array image, and P 0 3 and P 0 4 are the column coordinates of the left and right edges of the light band formed by parallel light B in the initial single-frame linear array image. Calculate the distance S between the two parallel light bands A and B, and the sum of the widths of the two parallel light bands A and B when the rotating body to be measured is not placed. W , S = P 0 3 – P 0 2 , W = P 0 4 -P 0 1 -S ; (2)Single-diameter measurement: The moving platform moves, and the rotary body to be measured is placed in the area enclosed by the moving platform, the ball screw, and the slide rail. The rotary body to be measured blocks part of the parallel light A and part of the parallel light B between the first triangular reflector and the second triangular reflector. The reading of the grating ruler is G. After being blocked, the two beams of light also form two light bands in the linear array camera. The monocular linear array camera obtains a single-frame linear array image with two parallel light bands after occlusion. Remove the background and noise of the single-frame linear array image after occlusion, and use the bilateral centroid method to extract the column coordinates of the edges of the parallel light bands P 1 1 ，P 1 2 , P 1 3 , P 1 4 , where P 1 1 and P 1 2 are the column coordinates of the left and right edges of the light band formed by the parallel light A in the single-frame linear array image after occlusion, respectively. P 1 3 and P 1 4 are the column coordinates of the left and right edges of the light band formed by the parallel light B in the single-frame linear array image after occlusion, respectively. Calculate the width of the parallel light A T 1 and the width of the parallel light band B T 2 , T 1 = P 1 2 - P 1 1 , T 2 = P 1 4 - P 1 3 , T=T 1 +T 2 ， According to the following formula, calculate the diameter D of the rotary body to be measured: D = S + G + W - T ； (3) Measuring the diameter in one week: The measured rotating body is fixed on the turntable, and the turntable drives the measured rotating body to rotate one week. The monocular line array camera collects the spatio-temporal images of the measured rotating body rotating one week in real time. Each frame image in the spatio-temporal images is a row, which is a single-frame line array image. According to step (2), calculate the diameter corresponding to each row of the single-frame line array image, and then obtain the diameter of the measured rotating body in one week.

7. The monocular vision-based dynamic measurement method for the diameter of a large-sized rotating body according to claim 6, wherein Step (1) is specifically: (101) The threshold method is used to remove the background and noise of the initial single-frame linear array image, and only the information of the parallel light band is retained: （2）； In the formula, is the gray value of the initial single-frame linear array image after removing the background and noise, and threshold is the threshold for background removal. is the gray value of the initial single-frame linear array image; (102) Adopt a local edge search algorithm to obtain the four edge column coordinates of the parallel light bands in the initial single-frame linear array image processed in step (101). P 0 1 , P 0 2 , P 0 3 , P 0 4 , calculate the distance S between the two parallel light bands A and B, and the sum of the widths of the two parallel light bands A and B when the measured rotating body is not placed. W .

8. The monocular vision-based dynamic measurement method for the diameter of a large-sized rotating body according to claim 6, wherein Step (2) is specifically as follows: (201) The threshold method is used to remove the background and noise of the single-frame linear array image after occlusion, and only the information of the parallel light band is retained: ； In the formula, is the gray value of a single-frame linear array image after removing the occlusion of the background and noise, and threshold is the threshold for background removal. is the gray value of the single-frame linear array image after occlusion; (202) Identify the transition center of the edge using the bilateral centroid method and extract the column coordinates of the light band edge using the bilateral centroid method P 1 2 , P 1 3 , while P 1 1 = P 0 1 , P 1 4 = P 0 4 ; ； where Lc is the central column coordinate of the dark area between two parallel light bands, m is the column coordinate in each row, is the gray value of the m-th column coordinate after the processing of step (201).

9. The monocular vision-based dynamic measurement method for the diameter of a large-sized rotating body according to claim 6, wherein Based on the diameter obtained in step (2) or (3), the radial end run of the measured rotating body can be detected.

10. The monocular vision-based dynamic measurement method for the diameter of a large-sized rotating body according to claim 6, characterized in that, Based on the diameter of one week of the rotating body obtained in step (3) and the rotation angle of the rotating body, the outer contour of the measured rotating body can be determined.

Images