A multi-line structured light projection device and coding and decoding method suitable for high temperature objects

Abstract

A kind of multi-line structured light projection device suitable for high-temperature object and coding and decoding method, through including laser array, motor shaft, servo motor, motor controller multi-line structured light projection device, using short wave laser array combined with motor, provide rich matching features for high-temperature object, reduce binocular matching difficulty, through combining the distance and topography depth of measured object, the placement position and mode of laser array are standardized, and the rapid decoding of multi-line structured light point is realized by projection ranging comparison, hardware structure is simple, the encoding and decoding process of structured light is also simple and clear, algorithm is easy to realize, greatly reduce the matching problem when using binocular vision technology to measure high-temperature object.

Description

TECHNICAL FIELD

[0001] The application relates to a multi-line structured light projection device suitable for a high-temperature object and a coding and decoding method, and belongs to the technical field of hypersonic speed test measurement and binocular stereo vision measurement. BACKGROUND

[0002] In the process of measuring the surface topography of a high-temperature object by using binocular stereo vision technology, the high-temperature image collected by the binocular camera is often in an overexposure state due to the interference of high-temperature radiation of the object, and lacks matching features, so that image processing is difficult, and the obtained three-dimensional topography has problems such as large data error and low resolution.

[0003] A conventional solution is to spray random speckles on the surface of the object to artificially increase the surface texture features of the object and reduce the difficulty of image matching. However, the artificial speckles change the real topography of the object, the material of the speckles may affect the high-temperature characteristics of the object to be measured, in addition, the adhesion of the speckles at high temperature will be reduced, and the falling off during the measurement process will also cause the actual application effect to be unsatisfactory. The active vision method of the dot matrix laser limits the data amount of the topography reconstruction point cloud. When the multi-line structured light method selected for the measurement of a normal-temperature object is used to measure a high-temperature object, the line structured light is covered by high-temperature light emission on the hardware, and the matching and recognition of the multi-line structured light image also need to be solved on the algorithm. SUMMARY

[0004] The application solves the technical problem that the conventional random speckle spraying method has many deficiencies in the prior art, and provides a multi-line structured light projection device suitable for a high-temperature object and a coding and decoding method.

[0005] The application solves the above technical problem by the following technical scheme:

[0006] A multi-line structured light projection device suitable for a high-temperature object, comprising a laser array, a motor shaft, a servo motor and a motor controller, the laser array is arranged directly above the motor shaft and is fixedly connected through a flange, the motor shaft is driven by the servo motor, the servo motor is controlled by the motor controller, and the laser array adjusts the projection angle to ensure that the projected laser covers the object to be measured within the corresponding measurement distance.

[0007] The servo motor and the motor controller are connected through a control line, the laser array is composed of two or more laser projectors, all the laser projectors are fixedly connected to the motor shaft through flanges, and the amplitude angle of each laser projector is adjusted according to the measurement distance between the object to be measured and the laser array, so that the projected laser can cover the object to be measured at different measurement distances.

[0008] The number of the laser is adjusted according to the corresponding measurement distance of the object to be measured, the projection line laser of the laser is a short wave band and the bandwidth is less than 20nm, the medium and long wave band light radiated by the object to be measured is compared through the non-physical bonding feature pattern of the projection line laser of the laser, and the laser measures the object to be measured through the short wave band projection line laser.

[0009] A multi-line structured light projection coding method suitable for high-temperature objects, comprising:

[0010] A multi-line structured light projection device is built, which includes a laser array, a motor shaft, a servo motor and a motor controller.

[0011] Before the test, the binocular stereo vision system is double-targeted to obtain the parameter information of the binocular stereo vision system, calculate the epipolar distance of the binocular stereo vision system, and determine the distance and the longitudinal depth of the object to be measured.

[0012] A plurality of line lasers for image matching are set, and under the premise of ensuring that the laser brightness exceeds the rest of the light on the surface of the measured object, the laser is adjusted so that the line laser projected on the surface of the measured object meets the requirements.

[0013] An ablation test is carried out, and a multi-line structured light scanning image of the object to be measured is obtained, and the center line of the light bar of the multi-line structured light scanning image is calculated through Gaussian filtering, image binarization and light bar thinning image processing.

[0014] The epipolar line constraint is used to calculate the epipolar line of the point on the light bar center line of the left image after image binarization on the right image, and the intersection point of the epipolar line and the light bar center line of the right image is defined as the matching candidate point set set1.

[0015] The three-dimensional point coordinates of all points in the candidate point set set1 are calculated to obtain a three-dimensional point cloud set set2.

[0016] All points in the three-dimensional point cloud set set2 are projected onto the Z axis and the epipolar distance straight line O l O r , and the vertical distance L i is calculated.

[0017] The three-dimensional point cloud coordinates of the points in the three-dimensional point cloud set set2 that meet the judgment condition are taken as correct three-dimensional point cloud coordinates, and the multi-line structured light projection coding of the object to be measured is completed.

[0018] The parameter information of the binocular stereo vision system includes an intrinsic matrix M l (M r ), a rotation matrix R, a translation vector T and an eigenmatrix F, wherein the epipolar distance B of the binocular stereo vision system is calculated as ||T||2, the distance L of the measured object to the measurement system is measured, and the field of view depth e1 of the measured object.

[0019] The linear laser is projected on the measured object, and is used for fine dense matching of an image, and the stripe width s is specifically set as:

[0020] s>k*Be1 / (L-e1), k is a relaxation coefficient, and the value range is (0.5, +infinity).

[0021] The judgment condition in the three-dimensional point cloud set set2 is specifically:

[0022] |L i -L|<s*L / (s+0.5B).

[0023] Before double target positioning, the servo motor position is zeroed, the positions, amplitudes and focal lengths of the lasers are adjusted, the object to be measured is completely covered by clear and uniform projected line lasers on any side of the object, and projection preview is performed; rotation instructions are sent to the servo motor through the motor controller until the projected line lasers uniformly sweep through the entire object to be measured, and the rotation angle and time of the servo motor when sweeping through the object to be measured are recorded.

[0024] After the projection preview is completed, the motor controller is parameter set, including the control parameter setting of the starting position and the ending position, the scanning speed and the pause time; after entering the projection working stage, the laser array is driven on the surface of the object to be measured through the preset control program to periodically and reciprocally scan and frame by frame collect the line structure light stripes, and the multi-line structure light projection encoding and decoding are performed.

[0025] The light stripe thinning process includes a gray center of gravity method, a skeleton thinning method and a steger method;

[0026] The three-dimensional coordinate system in which the candidate point set set1 and the three-dimensional point cloud set set2 are projected is a coordinate system of any camera required by double target positioning;

[0027] When all the points in the three-dimensional point cloud set set2 are projected on the Z axis, the x and y coordinates are forced to be zero;

[0028] In the process of calculating correct three-dimensional point cloud coordinates, if there are incorrect matching points that do not meet the judgment condition, the incorrect matching points are discarded.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] The multi-line structure light projection device and encoding and decoding method suitable for high-temperature objects provided by the present application can realize a non-physical bonding, high-contrast feature pattern on the surface of the measured object through the multi-line laser combined with the motor rapid scanning mode, the matching algorithm is simple and efficient and has a low error matching rate, meanwhile, the short-wave line laser can be applied to the visual measurement of the surface topography of the high-temperature object, and through the multi-line structure light rapid periodic scanning method, dense and fine point cloud data can be obtained in real time and dynamically. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The schematic diagram of the multi-line structured light projection device provided for the invention;

[0032] Figure 2 The measurement schematic diagram of the multi-line structured light projection device provided for the invention combined with two cameras;

[0033] Figure 3 The schematic diagram of the projection light path provided for the invention; DETAILED DESCRIPTION

[0034] A multi-line structured light projection device and coding and decoding method suitable for high-temperature objects, through the multi-line structured light projection device including a laser array, a motor shaft, a servo motor, and a motor controller, a short-wave laser array is combined with a motor to provide rich matching features for high-temperature objects, reduce the difficulty of binocular matching, through the combination of the distance and the topographic depth of the object to be measured, the placement position and mode of the laser array are standardized, and the rapid decoding of the multi-line structured light points is realized through the projection distance comparison, the hardware structure is simple, the coding and decoding process of the structured light is simple and clear, the algorithm is easy to implement, and the matching problem of the binocular vision technology when measuring high-temperature objects is greatly reduced.

[0035] The laser array is arranged directly above the click motor shaft and is fixedly connected through a flange, the motor shaft is driven by the servo motor, the servo motor is controlled by the motor controller, the laser array adjusts the projection angle to ensure that the projected laser covers the object to be measured within the corresponding measurement distance, the servo motor and the motor controller are connected through a control line, the laser array is composed of two or more line lasers, all the lasers are fixedly connected to the motor shaft through a flange, and the amplitude angle of each laser is adjusted according to the measurement distance of the object to be measured and the laser array to ensure that the projected laser can cover the object to be measured at different measurement distances;

[0036] The number of lasers is adjusted according to the corresponding measurement distance of the object to be measured, the projection line laser of the laser is a short-wave laser with a bandwidth less than 20 nm, the medium-long wave band light radiated by the object to be measured is compared through the non-physical bonding feature pattern of the projection line laser of the laser, and the laser performs visual measurement on the object to be measured through the short-wave projection line laser.

[0037] The multi-line structured light projection coding and decoding method suitable for high-temperature objects includes the following specific steps:

[0038] Before the test, the double targets of the binocular stereo vision system are calibrated, the parameter information of the binocular stereo vision system is obtained, the epipolar distance of the binocular stereo vision system is calculated, and the distance and the longitudinal depth of the object to be measured are determined;

[0039] The multiple linear lasers are projected on the measured object, and are used for fine dense matching of images.

[0040] An ablation test is carried out, a multi-line structured light scanning image of the measured object is obtained, and a light strip center line of the multi-line structured light scanning image is calculated through Gaussian filtering, image binarization and light strip thinning image processing;

[0041] The epipolar line of a point on the light strip center line of the left image after image binarization on the right image is calculated, and the intersection of the epipolar line and the light strip center line of the right image is defined as a matching candidate point set set1.

[0042] The three-dimensional point coordinates of all points in the candidate point set set1 are calculated to obtain a three-dimensional point cloud set set2.

[0043] The three-dimensional coordinate system in which the candidate point set set1 and the three-dimensional point cloud set set2 are projected is an arbitrary camera coordinate system required for binocular object positioning, that is, a coordinate system in which a left camera or a right camera of a binocular camera is located.

[0044] All points in the three-dimensional point cloud set set2 are projected onto the Z-axis and the epipolar distance straight line O l O r , and the perpendicular distance L i is calculated.

[0045] The three-dimensional point cloud coordinates of the three-dimensional point cloud set set2 that satisfy the judgment condition are taken as correct three-dimensional point cloud coordinates, and the multi-line structured light projection encoding and decoding of the measured object are completed.

[0046] The following further describes in combination with the drawings and preferred embodiments of the specification:

[0047] In the current embodiment, a structured light projection device suitable for high-temperature environments is composed of a servo motor system and a laser array. The servo motor system is composed of a controller and a motor and is connected through a control line. The laser array is located above the motor shaft and is fixedly connected with the shaft. Figure 1 As shown in the figure, the laser 1 and the flange 2 form a laser array, and the turntable 3 and the shaft 4 jointly form a motor shaft.

[0048] The laser array is composed of two or more lasers that can project linear lasers, and the number can be adjusted according to actual needs. The lasers are arranged in a radial manner, and the radial angle of each laser can be finely adjusted to ensure that the projected laser can cover objects at different measurement distances. The projection line laser of the laser is in the short-wave band, and the bandwidth is less than 20 nm, such as blue laser or purple laser. Since high-temperature objects radiate more light in the medium and long-wave bands, combined with narrowband filtering, the projection light of the laser can provide a non-physical bonding and high-contrast feature pattern for the measured object.

[0049] The initial preparation stage, the motor position to zero, adjust the laser position, amplitude angle, focal length, so that the object to be measured on one side (such as the left side) can be clearly and uniformly covered by the laser; projection preview stage, to the motor sends rotating instructions, so that the laser line uniform speed through the entire object to be measured, record the final scan object when the motor rotation angle and time; parameter setting stage, the motor controller input start position and end position, scanning speed, pause time and other control parameters; projection work stage, start the control program, so that the motor system driven laser array on the surface of the high temperature object for periodic reciprocating scanning, such as Figure 2 shown, each laser scans part of the surface of the model, and frame by frame acquires the line structure light stripe.

[0050] The multi-line structured light encoding and decoding method suitable for high temperature objects includes the following steps:

[0051] (1) Before the test, calibrate the binocular stereo vision system, obtain the intrinsic matrix M l (M r ), rotation matrix R, translation vector T and eigenmatrix F of the binocular stereo vision system, calculate the epipolar distance B = ||T||2 of the binocular stereo vision system, and keep the measured object and the measurement system basically parallel and facing each other, measure the estimated object distance L from the center of the measured object to the midpoint of the two cameras, and the field depth e1 of the measured object;

[0052] (2) According to the values of step (1), set the width of the stripe to s > k·Be1 / (L-e1), k is the relaxation coefficient, the value range is (0.5, +∞), and usually [0.6, 1] can be taken.

[0053] (3) Carry out ablation test, obtain multi-line structured light scanning image, and calculate light stripe center line through Gaussian filtering, image binarization, light stripe thinning and other image processing technologies. There are many public algorithms for light stripe thinning method, including gray centroid method, skeleton thinning method and steger method, which will not be described here;

[0054] (4) Use epipolar constraint to calculate the epipolar line on the right image of the point on the left image light stripe center line, and mark p l as any point on the left image light stripe center line. The parameter form of the corresponding epipolar line on the right image is Fp l , and the point on the right image light stripe center line closest to the epipolar line is taken as the intersection point of the epipolar line and the light stripe center line and form a matching candidate point set set1;

[0055] (5) Use the parameters obtained by calibration and p l , all in the candidate point set set1 to calculate each The corresponding three-dimensional point coordinates, and form a three-dimensional point cloud set set2;

[0056] (6) Project all points in the three-dimensional point cloud set set2 to the Z axis (x and y coordinates are forced to be set to zero), and project to the polar distance straight line O l O r Above, calculate L i ;

[0057] (7) The points in the three-dimensional point cloud set set2 |L i -L|<s·L / (s+0.5B) are taken as correct three-dimensional point cloud coordinates. The decoding principle is shown in Figure 3 Error matching points P1, P2 and P3, etc., the distance to the polar distance line will obviously deviate from the true position range of the object.

[0058] In the current embodiment, the multi-line structured light projection device structure is exquisite, and the non-physical bonding, high-contrast feature pattern on the surface of the measured object can be realized by the multi-line laser combined with the motor rapid scanning mode; the short-wave band line laser can be applied to the visual measurement of high-temperature objects.

[0059] Although the present application has been disclosed as above with the preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

[0060] The contents not described in detail in the specification of the present application belong to the known technology of those skilled in the art.

Claims

1. A multi-line structured light projection coding method suitable for high temperature objects, characterized in that The application relates to a multi-line structured light projection coding and decoding method suitable for high-temperature objects. The binocular stereo vision system is double-targeted before the test, parameter information of the binocular stereo vision system is acquired, the epipolar distance of the binocular stereo vision system is calculated, and the longitudinal depth of the distance measurement and the to-be-measured object is determined; A plurality of line lasers for image matching are arranged, the line lasers are adjusted on the premise that the laser brightness exceeds the rest of the light on the surface of the to-be-measured object, and the line lasers projected on the surface of the to-be-measured object are adjusted until the requirement is met; An ablation test is carried out, multi-line structured light scanning images of the to-be-measured object are acquired, and the center lines of the light strips of the multi-line structured light scanning images are calculated through Gaussian filtering, image binarization and light strip thinning image processing; The point on the light strip center line in the left image after image binarization is used to calculate the epipolar line of the point on the right image, and the intersection point of the epipolar line and the light strip center line of the right image is defined as a matching candidate point set set1; Three-dimensional point cloud set set2 is obtained by calculating the three-dimensional point coordinates of all points in the candidate point set set1. The points in the three-dimensional point cloud set set2 that meet the judgment condition are used as correct three-dimensional point cloud coordinates, and the multi-line structured light projection coding and decoding of the to-be-measured object are completed. Project all points in the three-dimensional point cloud set set2 onto the Z-axis and onto the polar distance straight line O l O r Above, calculate the perpendicular distance L i ; The line laser is projected on the measured object and used for fine dense matching of images, and the stripe width s is specifically set as follows: The parameter information of the binocular stereo vision system includes an intrinsic matrix M l 、 M r 、 a rotation matrix R, a translation vector T, and an essential matrix F, wherein a baseline B of the binocular stereo vision system is calculated as B = ||T||2, a distance L between the measured object and the measuring system is measured, and a field depth e1 of the measured object is obtained. s>k*Be1 / (L-e1), k is a relaxation coefficient, and the value range is (0.5, +infinity); The judgment condition in the three-dimensional point cloud set set2 is specifically as follows: Before double-targeting, the position of the servo motor is reset to zero, the positions, amplitudes and focal lengths of the lasers are adjusted, the to-be-measured object is completely covered by clear and uniform projected line lasers on any side of the to-be-measured object, and projection preview is carried out. |L i - L < s - L / (s + 0.5B); 2. The multi-line structured light projection coding and decoding method suitable for high-temperature objects according to claim 1, wherein: After the projection preview is completed, the parameters of the motor controller are set, including the control parameter setting of the starting position and the ending position, the scanning speed and the pause time, and after entering the projection working stage, the laser array is driven on the surface of the to-be-measured object through the preset control program, the line structured light stripes are periodically and reciprocally scanned and frame by frame collected, and the multi-line structured light projection coding and decoding are carried out.

3. The multi-line structured light projection coding and decoding method suitable for high-temperature objects according to claim 2, wherein: The light strip thinning processing includes the gray gravity center method, the skeleton thinning method and the steger method; The three-dimensional coordinate system in which the three-dimensional point cloud set set2 is projected is a coordinate system of any camera required by double-targeting; When all the points in the three-dimensional point cloud set set2 are projected onto the Z-axis, the x and y coordinates are forced to be zero; During the calculation of the correct three-dimensional point cloud coordinates, if there are incorrect matching points that do not meet the judgment condition, the incorrect matching points are discarded.

4. A multi-line structured light projection coding and decoding device for realizing the multi-line structured light projection coding and decoding method according to claim 3. ​ Including laser array, motor shaft, servo motor, motor controller, the laser array is arranged in the motor shaft directly above, and is fixedly connected through the flange, the motor shaft is driven through the servo motor, the servo motor is controlled by the motor controller, the laser array guarantees the projection laser to cover the object to be measured in the corresponding measurement distance through the adjustment projection angle; The servo motor and the motor controller are connected through the control line, the laser array is composed of more than two projective linear lasers, all the lasers are fixedly connected on the motor shaft directly above through the flange, the amplitude angle of each laser is adjusted according to the measurement distance of the object to be measured and the laser array, to ensure that the projected laser can cover the object to be measured at different measurement distances; The number of the laser is adjusted according to the corresponding measurement distance of the object to be measured, the projection linear laser of the laser is a short wave band and the bandwidth is less than 20nm, the medium and long wave band light radiated by the object to be measured is compared through the non-physical bonding feature pattern of the projection linear laser of the laser, and the laser is visually measured through the projection linear laser of the short wave band.

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