A cylindrical part positioning method based on double-line laser binocular vision

Abstract

The application discloses a cylindrical part positioning method based on double-line laser binocular vision. The method comprises the following steps: establishing an imaging model by using a binocular camera which has been calibrated; calculating the space equations of two straight lines by the imaging of double-line laser on the end surface of a cylindrical part in two cameras, and determining the space plane position of the end surface of the cylindrical part; establishing a binocular vision line-surface intersection model, calculating the space coordinates of four edge points by the four imaging points of double-line laser on the edge points of the cylindrical surface, and obtaining the center position of the circle of the end surface of the cylindrical part by the least square method, and then obtaining the three-dimensional pose of the cylindrical workpiece; and the application solves the three-dimensional high-precision positioning problem of the cylindrical workpiece.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cylindrical part positioning, in particular to a cylindrical part positioning method based on double-line laser binocular vision. BACKGROUND

[0002] In the textile chemical fiber industry, the large capacity of DTY spindles leads to a large demand for chemical fiber POY spindles, and the quality of a single POY spindles reaches 10-20 kg, which is difficult to recruit workers and increases labor costs. The three-dimensional space positioning of the cylindrical arc-shaped edge unwinding disc is a key problem restricting the automatic material changing of the spindles. At present, the loading process of the chemical fiber POY spindles is mainly manual, and the workload is huge. A single person needs to complete more than 20 tons of carrying per day, and the overall automation and intelligence level of the industry is low. In view of the space positioning problem of the unwinding disc of the chemical fiber bobbin, research is carried out on the 3D vision positioning system of the arc edge cylindrical part. The cylindrical barrel is a common carrier in the textile industry, and the three-dimensional fast and accurate positioning of the cylindrical barrel workpiece is the key to realizing the automatic material taking of such workpieces. The positioning of the cylindrical barrel workpiece includes the cylindrical direction positioning and the positioning of the center position of the cylindrical end face. For the three-dimensional space positioning of the arc edge cylindrical part, the conventional binocular stereo matching based on the corner feature points is difficult to achieve high positioning accuracy. The present application provides a cylindrical part positioning method based on double-line laser binocular vision. SUMMARY

[0003] The present application provides a cylindrical part positioning method based on double-line laser binocular vision. The three-dimensional high-precision positioning problem of the unwinding disc in the chemical fiber industry is solved.

[0004] The method comprises: establishing an imaging constraint model M of a space straight line under a binocular vision system; calculating the space equations of the two straight lines according to the imaging model M, and determining the space position of the plane where the cylindrical end face is located through the imaging of the double-line laser on the end face of the cylindrical part in the two cameras. A line-surface intersection model N of the binocular vision is established, and the space coordinates of the four edge points are calculated from the four groups of imaging points of the double-line laser on the edge of the cylindrical surface. The center position of the cylindrical end face circle is obtained through the least square method according to the space coordinates of the four edge points, and then the three-dimensional pose of the cylindrical workpiece is obtained, and the positioning is completed.

[0005] Optionally, the imaging model M of the space straight line under the binocular vision system comprises: the world coordinates of any two points on the to-be-measured space straight line in the imaging plane of the first camera are PA1 and PA2, and the world coordinates of the two points in the imaging plane of the second camera are PB1 and PB2; the coordinates of the origin of the first camera are TA, and the coordinates of the origin of the second camera are TB; the plane determined by TA, PA1 and PA2 is S1, and the plane determined by TB, PB1 and PB2 is S2; and the intersection line of the planes S1 and S2 is the space position of the to-be-measured space straight line.

[0006] Optionally, the spatial equations of the two straight lines are calculated according to the imaging model M through imaging of the double-line laser on the end face of the cylinder in the two cameras, and the spatial position of the plane where the end face of the cylinder is located is determined, including: the double-line laser is irradiated on the end face of the cylinder, and the binocular vision system acquires images; the world coordinates P11, P12 of the image points of the two edge points of the first laser line on the end face of the cylinder in the imaging plane of the first camera and the world coordinates P21, P22 of the image points of the two edge points of the first laser line on the end face of the cylinder in the imaging plane of the second camera are calculated through image processing, and the spatial position L1 of the first laser line on the end face of the cylinder is calculated according to the imaging model M; the world coordinates P13, P14 of the image points of the two edge points of the second laser line on the end face of the cylinder in the imaging plane of the first camera and the world coordinates P23, P24 of the image points of the two edge points of the second laser line on the end face of the cylinder in the imaging plane of the second camera are calculated through image processing, and the spatial position L2 of the first laser line on the end face of the cylinder is calculated according to the imaging model M; and the spatial position of the end face of the cylinder is calculated through the spatial straight lines L1 and L2.

[0007] Optionally, the spatial position of the end face of the cylinder is calculated through the spatial straight lines L1 and L2, including: two vertical feet V1 and V2 on the common perpendicular of the spatial straight lines L1 and L2 are calculated, and P=(V1+V2) / 2 is recorded. Since L1 and L2 are both on the end face of the cylinder, the P point can represent a feature point on the end face of the cylinder by ignoring the coplanar error. The direction vectors of the spatial straight lines L1 and L2 are recorded as n1 and n2, and the cross product of the two direction vectors is n3. The n3 is the direction vector of the end face of the cylinder. The point P and the direction vector n3 are the spatial position S of the end face of the cylinder.

[0008] Optionally, a binocular vision line-surface intersection model N is established, and the spatial coordinates of the four edge points are calculated from the four groups of imaging points of the double-line laser on the edges of the cylinder surface, including: the connecting lines of P11, P12, P13, P14 and the origin coordinates T1 of the first camera are recorded as L11, L12, L13, L14, and the intersection points of L11, L12, L13, L14 and the end face S of the cylinder are recorded as C11, C12, C13, C14. The connecting lines of P21, P22, P23, P24 and the origin coordinates T2 of the second camera are recorded as L21, L22, L23, L24, and the intersection points of L21, L22, L23, L24 and the end face S of the cylinder are recorded as C21, C22, C23, C24. The average of C11 and C21 is recorded as C1, the average of C12 and C22 is recorded as C2, the average of C13 and C23 is recorded as C3, and the average of C14 and C24 is recorded as C4. Then C1, C2, C3, C4 are the four edge points in the end face of the cylinder.

[0009] Optionally, the center position of the circle on the cylindrical end face is obtained, comprising: obtaining the center coordinate C of the circle on which C1, C2, C3 and C4 are located through the least square method, and completing the spatial positioning of the cylindrical end face.

[0010] The beneficial effects of the present application are:

[0011] The application discloses a cylindrical part positioning method based on double-line laser binocular vision. BRIEF DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and serve to explain the principles of the present application, and are not intended to limit the present application. In the drawings:

[0013] Figure 1 A flow chart of the cylindrical part positioning method based on double-line laser binocular vision.

[0014] Figure 2 An imaging constraint model diagram of a space straight line under a binocular vision system.

[0015] Figure 3 A space position diagram of double-line laser under the imaging constraint model. DETAILED DESCRIPTION

[0016] In order to make the personnel in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

[0017] According to the embodiment of the present application, an embodiment of a cylindrical part space positioning method based on double-line laser double-vision is provided. An imaging model is established using a double-vision camera which has been calibrated, the space equations of two straight lines are calculated through the imaging of the double-line laser lines on the end face of the cylindrical part in two cameras, and the space position of the cylindrical end face is determined; a double-vision line-surface intersection model is established, the space coordinates of four edge points are calculated through the four imaging points of the double-line laser on the edge points of the cylindrical surface, and the center position of the cylindrical end face circle is obtained through the least square method, and then the three-dimensional pose of the cylindrical workpiece is obtained; Figure 1 is a flow chart of a positioning method according to an embodiment of the present application, as shown in Figure 1 , the method comprises the following steps:

[0018] Step S102, an imaging constraint model M of a space straight line under a double-vision system is established.

[0019] Step S104, through the imaging of the double-line laser lines on the end face of the cylindrical part in two cameras, the space equations of two straight lines are calculated according to the imaging model M, and the space position of the plane where the cylindrical end face is located is determined.

[0020] Step S106, a double-vision line-surface intersection model N is established, the space coordinates of four edge points are calculated through four imaging points of the double-line laser on the edge of the cylindrical surface. According to the space coordinates of the four edge points, the center position of the cylindrical end face circle is obtained through the least square method, and then the three-dimensional pose of the cylindrical workpiece is obtained, and the positioning is completed.

[0021] The imaging model M of the space straight line under the double-vision system in step 102 is shown in Figure 2 , the world coordinates of any two points on the to-be-measured space straight line in the imaging plane of the first camera are PA1 and PA2, and the world coordinates of any two points on the to-be-measured space straight line in the imaging plane of the second camera are PB1 and PB2. The origin coordinates of the first camera are TA, and the origin coordinates of the second camera are TB. The plane determined by TA, PA1 and PA2 is S1, and the plane determined by TB, PB1 and PB2 is S2. The intersection line of the plane S1 and the plane S2 is the space position of the to-be-measured space straight line.

[0022] The specific steps for determining the space position of the plane where the cylindrical end face is located in step S104 are as follows: the double-line laser is irradiated on the cylindrical end face, and the double-vision system obtains an image; as Figure 3As shown, the world coordinates P11, P12 of the two edge points of the first laser line on the cylindrical end surface in the imaging plane of the first camera and the world coordinates P21, P22 of the two edge points of the second laser line on the cylindrical end surface in the imaging plane of the second camera are calculated by image processing, and the spatial position L1 of the first laser line on the cylindrical end surface is calculated according to the imaging model M; the world coordinates P13, P14 of the two edge points of the second laser line on the cylindrical end surface in the imaging plane of the first camera and the world coordinates P23, P24 of the two edge points of the second laser line on the cylindrical end surface in the imaging plane of the second camera are calculated by image processing, and the spatial position L2 of the first laser line on the cylindrical end surface is calculated according to the imaging model M; and the spatial position of the cylindrical end surface is calculated by the spatial straight lines L1 and L2.

[0023] The calculation of the spatial position of the cylindrical end surface by the spatial straight lines L1 and L2 includes: calculating two feet V1 and V2 on the common perpendicular of the spatial straight lines L1 and L2, and recording P=(V1+V2) / 2. Since L1 and L2 are both on the cylindrical end surface, the P point can be represented as a feature point on the cylindrical end surface by ignoring the coplanar error. The direction vectors of the spatial straight lines L1 and L2 are recorded as n1 and n2, and the cross product of the two direction vectors is n3. The n3 is the direction vector of the cylindrical end surface. The point P and the direction vector n3 are the spatial position S of the cylindrical end surface.

[0024] In step S106, a binocular vision line-surface intersection model N is established, and the spatial coordinates of the four edge points are calculated from the four imaging points of the double-line laser on the edge of the cylindrical surface. Including: the connecting lines of P11, P12, P13, P14 and the origin coordinates T1 of the first camera are recorded as L11, L12, L13, L14, and the intersection points of L11, L12, L13, L14 and the cylindrical end surface S are recorded as C11, C12, C13, C14. The connecting lines of P21, P22, P23, P24 and the origin coordinates T2 of the second camera are recorded as L21, L22, L23, L24, and the intersection points of L21, L22, L23, L24 and the cylindrical end surface S are recorded as C21, C22, C23, C24. The average of C11 and C21 is recorded as C1, the average of C12 and C22 is recorded as C2, the average of C13 and C23 is recorded as C3, and the average of C14 and C24 is recorded as C4. Then C1, C2, C3, C4 are the four edge points in the cylindrical end surface.

[0025] The center position of the circle on the cylindrical end surface is calculated according to the above four edge points, including: the center coordinates C of the circle in which C1, C2, C3, C4 are located are calculated by the least square method, and the spatial positioning of the cylindrical end surface is completed.

[0026] In the embodiment of the application, a binocular camera which has been calibrated is used to establish an imaging model; the spatial equations of two straight lines are calculated through the imaging of the double laser lines on the end face of the cylindrical part in two cameras, and the spatial plane position of the end face of the cylinder is determined; a binocular vision line-surface intersection model is established, the spatial coordinates of four edge points are calculated through the four imaging points of the double laser lines on the edge points of the cylindrical surface, and the center position of the circle of the end face of the cylinder is obtained through the least square method, and then the three-dimensional pose of the cylindrical workpiece is obtained; the three-dimensional high-precision positioning problem of the cylindrical workpiece is solved.

Claims

1. A cylindrical part positioning method based on double-line laser binocular vision, characterized in that, The method comprises the following steps: establishing an imaging constraint model M of a space straight line under a binocular vision system; calculating the space equations of the two straight lines according to the imaging constraint model M through the imaging of the double-line laser on the end face of the cylindrical part in the two cameras, and determining the space position of the plane where the end face of the cylinder is located; the step of calculating the space equations of the two straight lines according to the imaging constraint model M through the imaging of the double-line laser on the end face of the cylindrical part in the two cameras, and determining the space position of the plane where the end face of the cylinder is located, comprises: the double-line laser is irradiated on the end face of the cylinder, and the binocular vision system acquires images; calculating the world coordinates P11 and P12 of the two edge points of the first laser line on the end face of the cylinder in the imaging plane of the first camera and the world coordinates P21 and P22 of the two edge points in the imaging plane of the second camera through image processing, and calculating the space position L1 of the first laser line on the end face of the cylinder according to the imaging constraint model M; calculating the world coordinates P13 and P14 of the two edge points of the second laser line on the end face of the cylinder in the imaging plane of the first camera and the world coordinates P23 and P24 of the two edge points in the imaging plane of the second camera through image processing, and calculating the space position L2 of the first laser line on the end face of the cylinder according to the imaging constraint model M; calculating the space position S of the end face of the cylinder through the space straight lines L1 and L2; establishing a binocular vision line-surface intersection model N, and calculating the space coordinates of the four edge points through the four groups of imaging points of the double-line laser on the edge of the cylindrical surface; the step of establishing the binocular vision line-surface intersection model N and calculating the space coordinates of the four edge points through the four groups of imaging points of the double-line laser on the edge of the cylindrical surface, comprises: the connecting lines of P11, P12, P13 and P14 and the origin coordinates T1 of the first camera are recorded as L11, L12, L13 and L14, and the intersection points of L11, L12, L13 and L14 and the end face S of the cylinder are recorded as C11, C12, C13 and C14; the connecting lines of P21, P22, P23 and P24 and the origin coordinates T2 of the second camera are recorded as L21, L22, L23 and L24, and the intersection points of L21, L22, L23 and L24 and the end face S of the cylinder are recorded as C21, C22, C23 and C24; the average value of C11 and C21 is recorded as C1, the average value of C12 and C22 is recorded as C2, the average value of C13 and C23 is recorded as C3, and the average value of C14 and C24 is recorded as C4, so that C1, C2, C3 and C4 are the four edge points in the end face of the cylinder; the center position of the circle of the end face of the cylinder is obtained through the least square method according to the space coordinates of the four edge points, and then the three-dimensional pose of the cylindrical workpiece is obtained, and the positioning is completed.

2. The method of claim 1, wherein, the imaging constraint model M of a space straight line under a binocular vision system, comprises: The world coordinates of any two points on the space straight line to be measured on the imaging plane of the first camera are PA1 and PA2, and the world coordinates of the two points on the imaging plane of the second camera are PB1 and PB2. The coordinates of the origin of the first camera are TA, and the coordinates of the origin of the second camera are TB. A plane determined by the three points TA, PA1 and PA2 is denoted as S1, and a plane determined by the three points TB, PB1 and PB2 is denoted as S2. The intersection line of the plane S1 and the plane S2 is the spatial position of the space straight line to be measured.

3. The method of claim 1, wherein, The spatial position of the cylindrical end face is calculated according to the space straight lines L1 and L2, comprising: Two vertical feet V1 and V2 on the common perpendicular of the space straight lines L1 and L2 are calculated, and P=(V1+V2) / 2 is recorded. Since L1 and L2 are on the cylindrical end face, the common plane error is ignored, and the point P can represent a feature point on the cylindrical end face, The direction vectors of the space straight lines L1 and L2 are denoted as n1 and n2, and the cross product of the two direction vectors is n3. The direction vector n3 is the direction vector of the cylindrical end face, and the point P and the direction vector n3 are the spatial position S of the cylindrical end face.

Images