CN107121079B - A device and method for measuring surface height information based on monocular vision - Google Patents

Abstract

The invention belongs to the related field of machine vision imaging technology, and discloses a device and method for measuring the height information of a curved surface based on monocular vision, including a measuring frame, a parallel light source assembly, a detection camera and a distance sensor, wherein the parallel light source assembly consists of a mounting box , a collimator and a transmission grating, and the transmission grating is engraved with alternate wide and narrow parallel notches, so that the parallel light beam emitted by the collimator can be projected on the surface to be tested to form parallel stripes of light and dark; in addition, the detection The number of the camera is only one and it cooperates with the parallel light source component, so that the parallel stripes formed on the surface to be tested are captured to obtain an image. The invention also discloses a corresponding method for measuring the height information of the curved surface. Through the present invention, not only only a single camera can be used to complete the height information measurement of the curved surface with high efficiency, but also the overall structure is compact and reasonable, easy to operate, strong adaptability, and at the same time, the final obtainable measurement accuracy is significantly improved.

Description

A device and method for measuring surface height information based on monocular vision

technical field

The invention belongs to the related field of machine vision imaging technology, and more specifically relates to a device and method for measuring curved surface height information based on monocular vision.

Background technique

In vision technology, in order to measure the height information of a curved surface, at least multiple images of the measured curved surface need to be obtained from multiple angles. Existing methods usually use two or more cameras to collect images, and use geometric constraints to obtain three-dimensional information of the measured surface; or use only one camera to collect images from multiple angles. However, for the former, since it is necessary to use multiple cameras, while increasing the cost, there is also the problem of very cumbersome calibration of the internal and external parameters of the camera in a multi-camera system, and it often has a great impact on the final measurement accuracy. For the latter, although only one camera is used, the spatial position of the camera usually needs to be changed frequently during operation. The operation is cumbersome and often cannot guarantee the precise moving position, which will also be detrimental to the final measurement accuracy.

Through searching, it is found that CN201510248456.4 discloses a monocular vision sensor with triangular ranging function, which emits a laser beam from a laser, forms a collimated laser beam after passing through a focusing lens group, and forms a laser spot on the surface of the measured target The imaging lens group images the measured target (together with the laser spot) on the surface of the imaging device, and then obtains the two-dimensional information and distance information of the measured target through calculation, thereby realizing the use of the monocular vision sensor to obtain the measured target. three-dimensional information.

However, further studies have shown that the above-mentioned existing solutions are only suitable for the measurement of planar objects, and it is difficult to use them effectively in the application of curved surface object measurement; in particular, it can only measure the distance information from the measured object to the camera, but cannot Obtain the deformation information of the measured object in the out-of-plane direction, and the latter is a very critical indicator for surface measurement applications. Correspondingly, there is an urgent need in the art to seek a more complete solution to the above technical problems so as to meet the current increasing technological requirements.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention provides a device and method for measuring curved surface height information based on monocular vision, in which, in combination with the specific requirements of various curved surface measurement applications and the characteristics of actual working conditions, the measurement The overall structural layout of the device, as well as the specific composition and setting methods of multiple key components, etc. have been redesigned, and the measurement algorithm has been researched and improved. Compared with the existing surface measurement scheme, not only Using a single camera can efficiently complete the measurement of surface height information, and the overall structure is compact and reasonable, easy to operate, strong adaptability, and at the same time significantly improve the final measurement accuracy, so it is especially suitable for the application of surface information measurement.

In order to achieve the above object, according to one aspect of the present invention, a device for measuring surface height information based on monocular vision is provided, which device includes a measuring frame, a parallel light source assembly, a detection camera and a distance sensor, and is characterized in that:

The measuring frame is in the form of a symmetrical cross frame arranged horizontally and serves as the installation basis for other components;

The number of the parallel light source components is four, and they are respectively installed under the ends of the four identical arm structures of the measurement rack, and can be driven to rotate by matching motors to change the projection angle; each The parallel light source components are respectively composed of an installation box, and a collimator and a transmission grating respectively arranged inside the installation box, wherein the collimator is used to emit parallel light beams to the transmission grating, and the transmission grating is engraved with width The two alternate parallel notches also have light-transmitting slits alternated in width and width, so that the parallel light beams emitted by the collimator can be projected on the surface to be measured to form parallel stripes of light and dark;

The number of the detection camera is only one, which is fixedly installed under the center of the measurement frame, and cooperates with each of the parallel light source components, and is used to collect images of the parallel stripes formed on the surface to be measured to obtain the desired 2D image;

In addition, a camera Cartesian coordinate system XYZ is established with the lens optical center of the detection camera as the origin, wherein the Z axis of the camera Cartesian coordinate system coincides with the optical axis of the detection camera and points below the detection camera, and its X axis , the Y-axis satisfies the right-hand rule, and two of the four parallel light source assemblies remain symmetrically on this X-axis, and the remaining two also remain symmetrically on this Y-axis; similarly, with the detection camera The center of the imaging plane is the origin to establish an image Cartesian coordinate system X'Y'Z, wherein the Z axis of the image Cartesian coordinate system coincides with the Z axis of the camera Cartesian coordinate system, and its X' axis and Y' axis are the same Satisfy the right-hand rule; then, establish a reference rectangular coordinate system X"Y"Z directly below the detection camera, wherein the Z axis of the reference rectangular coordinate system coincides with the optical axis of the detection camera, and its X" axis , Y "axis also satisfies the right-hand rule, and its X"Y" plane remains parallel to the XY plane of the Cartesian coordinate system of the camera;

The distance sensors are arranged corresponding to each of the parallel light source components, and when the height of the measurement frame is adjusted so that the detection camera can obtain a clear two-dimensional image, it is used to measure the distance at this position. The vertical distance H between the optical center of the lens of the detection camera and the X"Y" plane is measured, and is used to detect the parallelism between the imaging plane of the detection camera and the X"Y" plane.

As a further preference, for each of the parallel light source components, the initial projection angle α between its optical axis and the XY plane is preferably calculated by the following formula:

α＝sin ^-1 (d/d ₀ )

In the formula, d represents the grating constant of the transmission grating of each of the parallel light source components; d ₀ represents the distance between two adjacent stripes in the parallel stripes formed on the X"Y" plane. center distance.

As further preferably, for the two parallel light source assemblies on the X-axis, the fringes formed by the two projections on the curved surface to be measured are parallel to each other and form a first fringe group; for the two parallel light source assemblies on the Y-axis For the two parallel light source components above, the fringes formed by the two projections on the curved surface to be measured are also parallel to each other and constitute the second fringe group; in addition, the difference between the first fringe group and the second fringe group perpendicular to each other.

As further preferably, for the light-transmitting wide slits and light-transmitting narrow slits in the light-transmitting slits respectively provided by the transmission gratings, their positions are coded and sorted in n-bit binary mode, and preferably the n×2 ⁿ The number of light-transmitting slits is encoded; the value of n is determined according to the field of view of the detection camera, and it is ensured that the number of stripes in the image obtained by the detection camera should satisfy m>3n-1; in addition, the The width ratio between the light-transmitting narrow slit d ₂ and the light-transmitting wide slit d ₁ preferably satisfies the formula d ₁ /d ₂ ≥2.

As a further preference, for the two parallel light source components on the X-axis, the X-axis coordinate x of any point P on the stripe formed by projection on the curved surface to be measured is preferably calculated by the following formula out:

x=x'×(D×tana _x )/(f-x'tana _x )

In the formula, D represents the distance between the optical center of the lens of the collimator of each of the parallel light source components and the optical center of the lens of the detection camera; _f is the focal length of the detection camera; The projection angle between the optical axis of each parallel light source assembly on the axis and the XY plane; x' respectively represents the pixel point P' corresponding to the point P in the two-dimensional image obtained by the detection camera The X' axis coordinate value of .

As a further preference, for the two parallel light source components on the Y-axis, the Y-axis coordinate y of any point P projected on the curved surface to be measured to form stripes is preferably calculated by the following formula out:

y=y'×(D×tana _y )/(f-y'tana _y )

In the formula, D represents the distance between the optical center of the lens of the collimator of each of the parallel light source components and the optical center of the lens of the detection camera; _f is the focal length of the detection camera; The projection angle between the optical axis of each parallel light source assembly on the axis and the XY plane; y' respectively represents the pixel point P' corresponding to the point P in the two-dimensional image obtained by the detection camera The Y' axis coordinate value of .

As a further preference, for the two parallel light source components on the X axis, the deformation amount h _x of any point P on the stripes formed on the curved surface to be measured in the direction of the Z axis preferably passes through The following formula is calculated:

h _x ＝|x–{(H cota _x -D)±(k _x ×d/sina _x )}|×tana _x

In the formula, x represents the X-axis coordinate value of any point P on the stripe formed by each parallel light source component located on the X-axis projected on the curved surface to be measured; H represents when the detection camera can obtain a clear image of the two dimensional image, the vertical distance between the lens center of the detection camera and the X"Y"plane; a _x respectively represent the distance between the optical axis of each parallel light source assembly on the X axis and the XY plane Projection angle; D represents the distance between the optical center of the lens of the collimator of each of the parallel light sources and the optical center of the lens of the detection camera; d represents the grating constant of the transmission grating of each of the parallel light source components; in addition , k _x represents the serial number of the fringe that includes point P among the multiple parallel fringes formed by the projection of each parallel light source component on the X-axis on the surface to be measured, k _x is a natural number, and starts from the most central point along the X-axis Streaks start counting.

As further preferably, for the two parallel light source components on the Y axis, the deformation amount h _y of any point P on the stripe formed on the curved surface to be measured in the direction of the Z axis preferably passes through The following formula is calculated:

h _y ＝|y–{(H cota _y -D)±(k _y ×d/sina _y )}|×tana _y

In the formula, y represents the Y-axis coordinate value of any point P on the stripe formed by each parallel light source component located on the Y-axis projected on the curved surface to be measured; H represents when the detection camera can obtain a clear image of the two dimensional image, the vertical distance between the lens center of the detection camera and the X"Y"plane; a and _y respectively represent the distance between the optical axis of each parallel light source assembly on the Y axis and the XY plane Projection angle; D represents the distance between the optical center of the lens of the collimator of each of the parallel light sources and the optical center of the lens of the detection camera; d represents the grating constant of the transmission grating of each of the parallel light source components; in addition , k _y represents the serial number of the fringe that includes point P among the multiple parallel fringes formed by the projection of each parallel light source component on the Y-axis on the surface to be measured, k _y is a natural number, and starts from the centermost point along the Y-axis Streaks start counting.

According to another aspect of the present invention, a corresponding method for measuring curved surface height information is also provided, characterized in that the method includes the following steps:

Step 1: first use the four distance sensors to measure the distance information to the X"Y" plane respectively, and adjust the X"Y" plane pose according to the obtained distance information so that it is kept in line with the imaging plane of the detection camera Parallel; at the same time, compensate the difference in the Z-axis direction between the distance sensor and the optical center of the detection camera, and then measure and determine the distance between the optical center of the detection camera and the X"Y" plane The vertical distance H;

Step 2: Use the set of parallel light source components to project bright stripes with alternate widths and narrow widths on the surface to be tested, and use the motor to drive the parallel light source components to rotate, so that the stripes slowly sweep across the entire area to be tested; the detection camera Take a picture, and write down the projection angle α of each image; then, use the remaining three groups of parallel light source components in turn, repeat the above steps, and obtain four images of the region to be measured under the stripes projected by the four groups of parallel light source components. group image;

Step 3: For the obtained four sets of images, calculate the deformation of any point P in the Z-axis direction on the stripes formed by each of the parallel light source components projected on the surface to be measured, and then calculate the average value by weighting method to calculate the actual deformation;

Step 4: Move the measurement rack, traverse the entire surface to be measured in sequence, and repeat steps 1 to 3 until the height information of all points on the entire surface to be measured is obtained, thereby completing the overall surface height measurement process.

Generally speaking, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

1. In the present invention, the overall structural layout of the curved surface height information measuring device is redesigned, especially the specific composition and arrangement of some key components such as the measurement frame, parallel light source components and detection cameras are improved. Correspondingly, not only can The overall measurement process of surface height information can be completed by using a single camera, and compared with existing equipment, its structure is more compact and reasonable, easy to operate, and significantly improves the final measurement accuracy;

2. The parameter selection of each component in the present invention can be selected according to the required measurement accuracy, correspondingly, in practical applications, it has strong applicability and is convenient for efficient operation according to working conditions; for example, when the measurement accuracy is not high, it can be selected by The operation is carried out by increasing the fringe spacing of the parallel light source assembly according to the present invention, thus reducing the measurement data and improving the measurement speed, and at the same time, it is also beneficial to increase the field of view of the camera, which greatly improves the measurement speed; and when the measurement accuracy requires When it is high, it can be operated by reducing the fringe spacing, the measurement data increases, and the accuracy is improved; at the same time, it is also beneficial to reduce the field of view of the camera and increase the image pixels, which also greatly improves the measurement accuracy;

3. In the present invention, the fringe encoding method is also optimized in combination with the structural characteristics of the parallel light source assembly, so that each fringe can be quickly identified in the image processing process, and the detection speed is accelerated; in addition, in the present invention, groups of parallel The light source can form multiple groups of stripes, which not only avoids the problem that the stripes on one side cannot be projected due to large changes in the curved surface, but also can measure the same point multiple times, and obtain more accurate height information through calculation;

4. In the present invention, combined with the characteristics of the above-mentioned device structure design, the coordinate values and deformation calculation formulas of each measurement point on the XYZ multi-axis are further targeted for measurement. Actual tests show that not only the calculation process can be simplified, but also the calculation formula can be calculated. Compared with the actual data, the obtained data has the characteristics of high precision and convenient subsequent processing, so compared with the traditional processing algorithm, the final precision of the surface height measurement can be significantly improved.

Description of drawings

1 is a schematic diagram of the overall structure of a monocular vision-based surface height information measuring device constructed according to a preferred embodiment of the present invention;

Fig. 2 is a schematic diagram of the specific layout of the measuring frame shown in Fig. 1 and the parallel light source assembly, the distance sensor and the detection camera installed thereon;

FIG. 3 is a schematic diagram for exemplarily illustrating multiple coordinate systems constructed to facilitate post-calculation processing;

4 is a schematic diagram of the composition and structure of a parallel light source assembly designed according to a preferred embodiment of the present invention;

FIG. 5 is a schematic diagram for exemplarily illustrating the formation of multiple stripes by projection of parallel light source components;

Fig. 6 is a schematic diagram obtained by encoding a plurality of stripes formed by parallel light source components according to the preferred implementation of the present invention;

Fig. 7 is a schematic diagram for explaining the measurement of the height information of the curved surface with the detection camera as the center and using the geometric principle of triangulation;

Fig. 8 is a schematic diagram for exemplarily illustrating fringes projected on the X"Y" plane by the above measuring device according to the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

Fig. 1 is a schematic diagram of the overall structure of a monocular vision-based surface height information measuring device constructed according to a preferred embodiment of the present invention, and Fig. 2 is a measurement frame shown in Fig. 1 and a parallel light source assembly, a distance sensor and a parallel light source assembly installed thereon. Schematic diagram of the specific layout of the detection camera. As shown in FIGS. 1 and 2 , the deflection corrector mainly includes components such as a measuring frame 10 , a parallel light source assembly 30 , a detection camera 20 , and a distance sensor 40 , which will be described in detail below.

The measurement frame 10 in the present invention can be designed in the form of a horizontally arranged symmetrical cross frame, and serves as the installation basis for other components.

The number of parallel light source assemblies 30 is four, and they are respectively installed under the ends of the four identical arm structures of the measurement frame 10, and can be driven to rotate through the matching motor 50 to change the projection angle, Wherein, the motor 50 is fixed on the measuring frame, and the parallel light source assembly 30 is connected to the motor shaft, that is, the motor 50 can drive the parallel light source assembly 30 to rotate; more specifically, as shown in FIG. 2 . As one of the key improvements of the present invention, each collimated light source assembly is composed of an installation box 31, and a collimator 32 and a transmission grating 33 respectively arranged inside the installation box, wherein the collimator 32 is used to The transmission grating 33 emits monochromatic parallel light beams, and the transmission grating 33 is engraved with two kinds of parallel notches with alternate widths and narrow ones, that is, it has light transmission slits with alternate widths and narrow ones, so that the parallel light beams emitted by the collimator 32 It can be projected to form light and dark parallel stripes on the surface to be tested.

Referring to FIG. 4 at the same time, it can be seen that in the parallel light source assembly 30 , the collimator 32 and the transmission grating 33 are fixed in the installation box 30 . The collimator 32 can generate parallel monochromatic light beams; the transmission grating 33 is engraved with opaque parallel notches as shown in FIG. 5 , thereby forming light-transmitting slits with different widths between the notches. The distance between the center line of the light-transmitting slit and the center line of the adjacent notch is the grating constant d, the width of the light-transmitting wide slit is d ₁ , and the width of the light-transmitting narrow slit is d ₂ . The parallel light emitted by the collimator 32 passes through the transmission grating 33 to form stripes with different widths on the curved surface to be measured. In order to avoid light diffraction, the monochromatic light wavelength λ of the collimator 32 should be selected according to the width of the light transmission slit, but must be smaller than the width of the light transmission slit, that is, λ<min{d ₁ ,d ₂ }. Then choose according to the accuracy requirements, the smaller the wavelength λ, the less obvious the diffraction phenomenon.

In addition, according to a preferred embodiment of the present invention, as shown in FIG. 6, the streaked light beam generated by the parallel light source assembly 30 can form a plurality of stripes on the X"Y" plane, where "1" is used to represent the thin stripes, and "0" is used to represent the stripes. ” indicates thick stripes. Through this encoding method, the corresponding relationship between the fringes on the curved surface to be measured and the fringes on the X"Y" plane in the image captured by the detection camera 20 can be identified. When the detection camera 20 captures that the stripe on the surface to be tested is "001010011", there are three possible results: "0", "010", "100", "11", "00", "101", "001", "1" and "001""010" and "011" respectively correspond to serial numbers "x ₁ 23x ₂ ", "x ₃ 51x ₄ ", and "123". Among them, x ₁ is not 1 and x ₂ is greater than 4, so the first group is wrong; the second group of sequences is also wrong; therefore, only the third group of sequences remains, and it conforms to the coding rules. Every fringe in the field of view is correctly identified.

As another key improvement of the present invention, the number of detection cameras 20 is only one, which is fixedly installed under the center of the measurement frame 10, and cooperates with each of the parallel light source assemblies 30 to be used on the curved surface to be measured. The formed parallel fringes perform imaging to obtain the desired two-dimensional image.

In addition, as exemplarily shown in FIG. 3 , a camera Cartesian coordinate system XYZ can be established with the optical center of the lens of the detection camera 20 as the origin, wherein the Z axis of the camera teaching coordinate system coincides with the optical axis of the detection camera 20 and Pointing to the bottom of the detection camera, its X-axis and Y-axis satisfy the right-hand rule, and two of the four parallel light source assemblies 30 remain symmetrically located on this X-axis, and the remaining two remain symmetrically located on this Y-axis on the axis; similarly, an image Cartesian coordinate system X'Y'Z is established with the center of the imaging plane of the detection camera 20 as the origin, wherein the Z axis of the image Cartesian coordinate system and the Z axis of the camera teaching coordinate system coincides with each other, its X' axis and Y' axis also meet the right-hand rule; then, a reference rectangular coordinate system X"Y"Z is established directly below the detection camera 20, wherein the Z axis of the reference rectangular coordinate system is the same as The optical axes of the detection camera are coincident, and its X" axis and Y" axis also satisfy the right-hand rule, and its X"Y" plane remains parallel to the XY plane of the camera Cartesian coordinate system.

Referring again to Fig. 2, four distance sensors 40 are respectively arranged corresponding to each of the parallel light source assemblies 30, and when the height of the measuring frame 10 is adjusted so that the detection camera (20) can obtain a clear image of the two In the case of a three-dimensional image, it is used to measure the vertical distance H between the optical center of the lens of the detection camera 20 and the X"Y" plane at this position, and it is used to measure the imaging plane of the detection camera 20 and the The parallelism between the X"Y" planes is tested. The motor shaft of the motor 50 and the optical center of the detection camera 20 are on the parallel plane of the XY plane, and the lens optical center of the collimator 32 is on the straight line where the motor shaft is located, thereby ensuring that when the motor 50 rotates and changes the projection angle α angle , the relative position of the optical center of the lens of the collimator 32 and the optical center of the detection camera 20 remains unchanged, so the horizontal distance D thereof remains unchanged.

The measurement process according to the present invention will be explained more specifically below.

First, as shown in Fig. 7, it shows a schematic diagram of measuring the height information of a surface with the detection camera as the center and using the geometric principle of triangulation. Among them, only the parallel light source assembly 30 on the X-axis is drawn, and the stripes projected on the curved surface to be measured are parallel to the Y-axis, so only the X-axis coordinate information is needed; and the two groups of parallel light source assemblies 30 on the Y-axis , the stripes projected on the surface to be measured are parallel to the X-axis, so only the Y-axis coordinate information is required. The parallel light beams emitted by the collimator 32 pass through the transmission grating 33 to form coded stripes with alternating light and dark on the surface to be tested, covering the entire area to be tested. One of the stripes is used for illustration, and the center line of the stripe passes through the point P. At this time, the projection angle α is formed between the optical axis of the parallel light source assembly 30 on the X-axis and the XY plane.

Assuming that the camera coordinates of point P are (x, y, z), the image coordinates P′ of point P in the two-dimensional image captured by the detection camera 20 are (x′, y′). Then the coordinates of the point P on the stripe projected by the parallel light source assembly 30 on the X-axis on the curved surface to be measured in the X-axis direction are:

x=x'×(D×tana _x )/(f-x'tana _x ) (1-1)

In the formula, D represents the distance between the optical center of the lens of the collimator of each of the parallel light source components and the optical center of the lens of the detection camera; _f is the focal length of the detection camera; The projection angle between the optical axis of each parallel light source assembly on the axis and the XY plane; x' respectively represents the pixel point P' corresponding to the point P in the two-dimensional image obtained by the detection camera The X' axis coordinate value of .

The coordinates of the point P on the stripes projected by the parallel light source assembly 30 on the Y-axis in the Y-axis direction on the curved surface to be measured are:

y=y'×(D×tana _y )/(f-y'tana _y ) (1-2)

In the formula, D represents the distance between the optical center of the lens of the collimator of each of the parallel light source components and the optical center of the lens of the detection camera; _f is the focal length of the detection camera; The projection angle between the optical axis of each parallel light source assembly on the axis and the XY plane; y' respectively represents the pixel point P' corresponding to the point P in the two-dimensional image obtained by the detection camera The Y' axis coordinate value of .

Fig. 8 is a schematic diagram for exemplarily illustrating fringes projected on the X"Y" plane by the above measuring device according to the present invention. Further, it is also necessary to separately calculate the deformation amount of any point P on the stripes formed on the curved surface to be measured for the two parallel light source components on the X-axis and Y-axis in the direction of the Z-axis .

As shown in Figure 8, only the parallel light source assembly 30 on the X-axis is drawn on the curved surface to be measured to project stripes, which are parallel to the Y-axis, so only its X-axis coordinate information is needed; The stripes projected by the light source assembly 30 on the curved surface to be measured are parallel to the X-axis, so only the Y-axis coordinate information is required. Assuming that a certain fringe of the transmission grating 33 in the parallel light source assembly 30 on the X-axis is the central fringe, the coordinates of the point on the projected fringe in the X-axis direction are:

x ₀ ＝H×cota _x -D (1-3)

In the parallel light source assembly 30 on the Y axis, a certain stripe of the transmission grating 33 is the central stripe, and the coordinates of the point on the projected stripe in the direction of the Y axis are:

y ₀ ＝H×cota _y -D (1-4)

Since the stripes on the transmission grating 33 are equally spaced (i.e. the grating constant d), the X-axis coordinates of the stripes projected by the parallel light source assembly 30 on the X-axis on the X"Y" plane are:

x _k ＝x ₀ ±(k×d/sina _x ) (1-5)

In the formula, d is the grating constant; k is the kth stripe from the center zero stripe, the positive direction of the X axis is +, and the negative direction is -;

And then the Y-axis coordinates of each stripe projected by the parallel light source assembly 30 on the Y-axis on the X"Y" plane are:

y _k =y ₀ ±(k×d/sina _y ) (1-6)

Combining the above calculation formulas, correspondingly, for the two parallel light source components on the X-axis, the deformation of any point P on the stripes formed on the curved surface to be measured in the Z-axis direction The quantities h _x are preferably calculated by the following formulas, respectively:

h _x ＝|x–{(H cota _x -D)±(k _x ×d/sina _x )}|×tana _x

In the formula, x represents the X-axis coordinate value of any point P on the stripe formed by each parallel light source assembly located on the X-axis projected on the curved surface to be measured; H represents that when the detection camera (20) can obtain a clear During the two-dimensional image, the vertical distance between the lens center of the detection camera and the X"Y"plane; a _x respectively represent the optical axis of each parallel light source assembly on the X axis and the XY plane D represents the distance between the optical center of the lens of the collimator of each of the parallel light sources and the optical center of the lens of the detection camera; d represents the grating of the transmission grating of each of the parallel light source components. constant; in addition, k _x represents the sequence number of the fringe that includes point P among the multiple parallel fringes formed by the projection of each parallel light source component on the X-axis on the surface to be measured, and k _x is a natural number, and from along the X-axis The centermost stripe starts counting.

Similarly, for the two parallel light source components on the Y-axis, the deformation amount h _y of any point P on the stripes formed on the curved surface to be measured in the Z-axis direction is preferably respectively expressed by the following formulas Calculated:

h _y ＝|y–{(H cota _y -D)±(k _y ×d/sina _y )}|×tana _y

In the formula, y represents the Y-axis coordinate value of any point P on the stripe formed by each parallel light source assembly located on the Y-axis projected on the curved surface to be measured; H represents that when the detection camera (20) can obtain a clear During the two-dimensional image, the vertical distance between the lens center of the detection camera and the X"Y"plane; a and _y respectively represent the optical axis of each parallel light source assembly on the Y axis and the XY plane D represents the distance between the optical center of the lens of the collimator of each of the parallel light sources and the optical center of the lens of the detection camera; d represents the grating of the transmission grating of each of the parallel light source components. constant; in addition, k _y represents the sequence number of the fringe that includes point P among the multiple parallel fringes formed by the projection of each parallel light source component on the Y-axis on the surface to be measured, and k _y is a natural number, and from along the Y-axis The centermost stripe starts counting.

The above surface height information measurement process method can be summarized as follows main steps:

Step 1: First, use the four distance sensors 40 to measure the distance information to the X"Y" plane respectively, and adjust the pose of the X"Y" plane according to the obtained distance information to make it image with the detection camera 20 The planes remain parallel; at the same time, the difference in the Z-axis direction is compensated between the distance sensor 40 and the optical center of the detection camera 20, and then measured and determined from the optical center of the detection camera 20 to the X, Y "The vertical distance H between the planes;

Step 2: using the set of parallel light source assemblies 30 to project bright stripes with alternate widths and narrow widths on the surface to be measured, and using the motor 50 to drive the parallel light source assemblies 30 to rotate, so that the stripes slowly sweep across the entire area to be measured; The detection camera 20 captures a picture, and writes down the projection angle α of each image; then, uses the remaining three groups of parallel light source assemblies 30 in sequence, repeats the above steps, and obtains the stripes projected by the four groups of parallel light source assemblies 30 respectively Four sets of images of the area to be tested;

Step 3: For the obtained four sets of images, calculate the deformation of any point P in the Z-axis direction on the stripes formed by each of the parallel light source components projected on the surface to be measured, and then calculate the average value by weighting method to calculate the actual deformation;

Step 4: Move the measurement rack 10, traverse the entire surface to be measured in sequence, and repeat steps 1 to 3 until the height information of all points on the entire surface to be measured is obtained, thereby completing the overall surface height measurement process.

To sum up, the curved surface height information measuring device according to the present invention can not only use a single camera to complete the overall measurement process of curved surface height information, but also has a more compact and reasonable structure and is easier to manipulate than existing equipment, and significantly improves At the same time, it has a wider range of applications, which is convenient for efficient adjustment of operating parameters under various working conditions, so it is more suitable for various high-efficiency and high-precision surface height measurement applications.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (5)

1. a kind of curved surface elevation information measuring device based on monocular vision, which includes measurement rack (10), source of parallel light Component (30), detection camera (20) and range sensor (40), it is characterised in that:

The measurement rack (10) is in the form of horizontally disposed symmetrical cross frame, and the installation foundation as other assemblies；

The quantity of the source of parallel light component (30) is four, and it is identical that each is mounted on four for measuring rack (10) Below the end of arm configuration, and it can drive rotated so that its projected angle changes via matched motor (50) respectively Become；Each source of parallel light component sets up the parallel light tube inside this mounting box separately by mounting box (31) and successively respectively (32) it is collectively constituted with transmission grating (33), wherein the parallel light tube (32) is used to emit in parallel to the transmission grating (33) Homogeneous beam is then carved with opaque parallel scores on the transmission grating (33) and forms the different light penetrating slit of width between indentation Namely light transmission it is wide seam and light transmission narrow slit so that the parallel light tube (32) issue collimated light beam can be thrown on curved surface to be measured It penetrates to form light and dark parallel stripes；

The quantity of detection camera (20) is only one, it is fixedly mounted on the center lower section of measurement rack (10), and Matched with each source of parallel light component (30), for be formed by curved surface to be measured parallel stripes execution adopt figure to obtain Obtain required two dimensional image；

In addition, establish a camera rectangular coordinate system XYZ as origin using the optical center of lens of the detection camera (20), the wherein phase The Z axis of machine rectangular coordinate system and the optical axis coincidence of detection camera (20) and the lower section for being directed toward the detection camera, X-axis, Y-axis Meet the right-hand rule, and two holdings in four source of parallel light components (30) are symmetrically in this X-axis, residue two A same holding is symmetrically in this Y-axis；Similarly, it is built using the center of the imaging plane of detection camera (20) as origin An image rectangular coordinate system X ' Y ' Z is found, wherein the Z axis of the Z axis of the image rectangular coordinate system and the camera rectangular coordinate system It coincides, X ' axis, Y ' axis equally meet the right-hand rule；Then, a ginseng is established immediately below the detection camera (20) Rectangular coordinate system X " Y " Z is examined, wherein the optical axis coincidence of the Z axis with reference to rectangular coordinate system and the detection camera, X " axis, Y " Axis equally meets the right-hand rule, and its X " Y " plane keeps being parallel to each other with the X/Y plane of the camera rectangular coordinate system；

The range sensor (40) corresponds respectively to each source of parallel light component (30) and is arranged, and when by adjusting When the height of measurement rack (10) makes the detection camera (20) can get the clearly two dimensional image, for herein The optical center of lens of detection camera (20) is measured to the vertical range H between the X " Y " plane under position, simultaneously It is detected for the depth of parallelism between the imaging plane and X " Y " plane to this detection camera (20)；The motor (50) Motor shaft is on the parallel surface of the X/Y plane together with the optical center of detection camera (20), and the parallel light tube (32) optical center of lens is in the motor shaft institute on straight line, to guarantee to rotate when the motor (50) to change projected angle Angle when, the optical center of lens of the parallel light tube (32) and it is described detection camera (20) optical center between keep relative position not Become；

In addition, in two source of parallel light components in the X-axis, the two projected shape on curved surface to be measured At striped it is parallel to each other and constitute the first striped group；For in two source of parallel light components in the Y-axis, It is same parallel to each other and constitute the second striped group that the two projects the striped formed on curved surface to be measured, and first striped It is mutually perpendicular between group and the second striped group；For seam wide for the light transmission with for light transmission narrow slit, their position presses n Binary mode carries out coding and sorting order, and to this n × 2ⁿLight penetrating slit is encoded, and wherein the value of n is according to the detection phase The visual field size of machine determines, and ensures so that fringe number m should meet m > 3n-1 in detection camera image obtained；This Outside, the light transmission narrow slit d₂With the wide seam d of the light transmission₁Between wide-to-narrow ratio meet formula d₁/d₂≥2。

2. a kind of curved surface elevation information measuring device based on monocular vision as described in claim 1, which is characterized in that for For each source of parallel light component (30), the initial projections angle α between optical axis and the X/Y plane is counted by following formula It calculates and obtains:

α=sin^-1(d/d₀)

In formula, d indicates the grating constant that the transmission grating itself of each source of parallel light component has；d₀Indicate the X " Y " Be formed by plane in light and dark parallel stripes, the center between two stripeds adjacent to each other away from.

3. a kind of curved surface elevation information measuring device based on monocular vision as claimed in claim 2, which is characterized in that for For two source of parallel light components in the X-axis, any to be formed on striped is projected on curved surface to be measured The X axis coordinate x of point P is calculated by following equation respectively:

X=x ' × (D × tana_x)/(f-x’tana_x)

In formula, D indicates the optical center of lens of the parallel light tube of each source of parallel light component to the lens light of the detection camera The distance between heart；F is the focal length of the detection camera；a_xRespectively indicate each source of parallel light component being located in the X-axis Optical axis and the X/Y plane between projected angle；X ' is illustrated respectively in detection camera two dimensional image obtained, with The point P keeps the X ' axial coordinate value of corresponding pixel P '；

And in two source of parallel light components in the Y-axis, it projects to form item on curved surface to be measured The Y axis coordinate y of any point P on line is calculated by following equation respectively:

Y=y ' × (D × tana_y)/(f-y’tana_y)

In formula, D indicates the optical center of lens of the parallel light tube of each source of parallel light component to the lens light of the detection camera The distance between heart；F is the focal length of the detection camera；a_yRespectively indicate each source of parallel light component being located in the Y-axis Optical axis and the X/Y plane between projected angle；Y ' is illustrated respectively in detection camera two dimensional image obtained, with The point P keeps the Y ' axial coordinate value of corresponding pixel P '.

4. a kind of curved surface elevation information measuring device based on monocular vision as claimed in claim 3, which is characterized in that for For two source of parallel light components in the X-axis, any point P on curved surface to be measured on formed striped exists Deflection h in Z-direction_xIt is calculated respectively by following equation:

h_x=| x-{ (H cota_x-D)±(k_x×d/sina_x)}|×tana_x

In formula, x indicates that each source of parallel light component being located in the X-axis projects to form appointing on striped on curved surface to be measured The X axis coordinate value of one point P；H expression is when the detection camera (20) can get the clearly two dimensional image, the detection camera Lens centre to the vertical range between the X " Y " plane；a_xRespectively indicate each source of parallel light being located in the X-axis Projected angle between the optical axis of component and the X/Y plane；D indicates the optical center of lens of the parallel light tube of each source of parallel light To the distance between the optical center of lens of the detection camera；D indicates transmission grating itself tool of each source of parallel light component Standby grating constant；In addition, k_xIndicate that each source of parallel light component being located in the X-axis projects formation on curved surface to be measured Multiple parallel stripes in comprising P point striped serial number, k_xFor natural number, and started counting from the striped along X-axis bosom；

And in two source of parallel light components in the Y-axis, on curved surface to be measured on formed striped Any point P deflection h in the Z-axis direction_yIt is calculated respectively by following equation:

h_y=| y-{ (H cota_y-D)±(k_y×d/sina_y)}|×tana_y

In formula, y indicates that each source of parallel light component being located in the Y-axis projects to form appointing on striped on curved surface to be measured The Y axis coordinate value of one point P；H expression is when the detection camera (20) can get the clearly two dimensional image, the detection camera Lens centre to the vertical range between the X " Y " plane；a_yRespectively indicate each source of parallel light being located in the Y-axis Projected angle between the optical axis of component and the X/Y plane；D indicates the optical center of lens of the parallel light tube of each source of parallel light To the distance between the optical center of lens of the detection camera；D indicates transmission grating itself tool of each source of parallel light component Standby grating constant；In addition, k_yIndicate that each source of parallel light component being located in the Y-axis projects formation on curved surface to be measured Multiple parallel stripes in comprising P point striped serial number, k_yFor natural number, and started counting from the striped along Y-axis bosom.

5. a kind of method for executing the measurement of curved surface elevation information using device as claimed in claim 4, which is characterized in that should Method includes the following steps:

Step 1: measuring its range information for arriving the X " Y " plane first with four range sensors (40) respectively, X " Y " plane pose is adjusted according to gained range information, makes itself and detection camera (20) the imaging plane keeping parallelism；Together When, the difference between the range sensor (40) and described detection camera (20) optical center in Z-direction is compensated, then It measures and determines the optical center for detecting camera (20) to the vertical range H between the X " Y " plane；

Step 2: projecting the alternate bright fringes of width using one group of source of parallel light component (30) on curved surface to be measured, And drive the source of parallel light component (30) to rotate using the motor (50), so that the slow inswept entire region to be measured of striped；Institute It states detection camera (20) and adopts figure, and write down the projected angle α of each image；Then, successively using source of parallel light group described in three groups of residue Part (30), repeats the above steps, and respectively obtains the region to be measured under the striped that four groups of source of parallel light components (30) are projected Four groups of images；

Step 3: obtained four groups of images are directed to, calculate separately to obtain each source of parallel light component on curved surface to be measured Any point P to be formed on striped is projected in the deflection of Z-direction, and then ask in such a way that weighting is averaged to calculate Practical distortion amount out；

Step 4: traverse measurement rack 10, successively complete curved surface to be measured of traversal repeat step 1 to step 3, until Until the elevation information for obtaining entire curved surface all the points to be measured, whole curved surface height measurement process is thus completed.