阅读说明：本技术 一种用于飞机数字化对接的部件锁紧视觉定位方法 (Part locking visual positioning method for airplane digital butt joint ) 是由 郭洪杰 崔伟 秦立 赵林 邵云丽 于 2020-07-21 设计创作，主要内容包括：本发明涉及飞机装配技术领域,特别涉及一种用于飞机数字化对接的部件锁紧视觉定位方法。首先将锁球装置安装在数控定位器上,其次将定位球安装在飞机部件上,接着使用锁球装置底部的工业相机拍摄定位球,然后通过视觉算法,计算出定位球相对于锁球装置球窝的偏差Δx,Δy,Δz,驱动锁球装置在x轴与y轴方向分别移动Δx与Δy的长度,在垂直z方向对准定位球,再在z轴方向运行Δz的长度,使锁球装置接住定位球并进行锁定,完成飞机部件与数控定位器的连接。本发明取代了定位器抱球是靠人的视觉判断,减少了部件锁紧后的内应力,防止飞机部件的损坏,节省了人力资源,方便操作与使用。(The invention relates to the technical field of airplane assembly, in particular to a part locking visual positioning method for airplane digital docking. Firstly, a ball locking device is installed on a numerical control positioner, secondly, a positioning ball is installed on an airplane component, secondly, an industrial camera at the bottom of the ball locking device is used for shooting the positioning ball, secondly, the deviation delta x, delta y and delta z of the positioning ball relative to a ball socket of the ball locking device are calculated through a visual algorithm, the ball locking device is driven to move the length delta x and the length delta y in the directions of an x axis and a y axis respectively, the positioning ball is aligned in the direction vertical to the z axis, and then the length delta z is operated in the direction of the z axis, so that the ball locking device receives and locks the positioning ball, and the connection of the airplane component and the numerical control positioner is completed. The invention replaces the visual judgment of a locator for holding the ball, reduces the internal stress of the locked part, prevents the damage of the airplane part, saves the human resource and is convenient to operate and use.)

1. A part locking visual positioning method for airplane digital docking is characterized in that: firstly, a ball locking device (3) is arranged on a numerical control positioner (4), secondly, a positioning ball (2) is arranged on an airplane component (1), secondly, an industrial camera (5) at the bottom of the ball locking device (3) is used for shooting the positioning ball (2), secondly, the deviation delta x, delta y and delta z of the positioning ball (2) relative to the ball socket center of the ball locking device (3) is calculated through a visual algorithm in a computer (6), a control system in the numerical control positioner (4) converts the deviation delta x, delta y and delta z into the movement length of x, y and z, drives the numerical control positioner (4) to respectively advance the length of delta x and delta y in the directions of x axis and y axis, so that the ball locking device (3) aligns the positioning ball (2) in the direction vertical z, and secondly, controls the ball locking device (3) to advance the length of delta z axis, the ball locking device (3) is enabled to receive the positioning ball (2) and lock the positioning ball to complete the connection of the airplane component (1) and the numerical control positioner (4).

2. The visual positioning method for component locking of airplane digital docking according to claim 1, characterized in that: the visual algorithm is as follows:

s1, an image formed by shooting a positioning ball (2) by an industrial camera (5) is an ellipse, and according to the pinhole imaging principle,

wherein X, Y, Z is the coordinate of the sphere center of the positioning sphere (2) in the coordinate system of the positioning sphere (2) with the optical center of the industrial camera (5) as the origin, f is the focal length of the industrial camera (5), b_x，b_yThe coordinate of the center of the projection ellipse in the imaging plane is shown as a, the long axis of the ellipse in the picture is shown as a, the diameter of the positioning ball (2) is shown as D, and f is an inherent parameter of the industrial camera (5) and can be obtained by a standard calibration method;

s2, calculating the ideal coordinates of the sphere center of the positioning sphere (2) as follows:

（2）

s3, processing the image to obtain a and b_x，b_y；

S4, in fact, a picture shot by the industrial camera (5) is deformed and does not completely accord with the pinhole imaging principle, and the following equation can be obtained in consideration of the deformation influence:

（3）

in the formula A_x，B_x，C_x，A_y，B_y，C_y，A_z，B_z，C_zThe unknown number is obtained by calibration, and the calibration process is as follows: the coordinates of the positioning ball (2) in the coordinate system of the industrial camera (5) are respectively taken as (X)₁，0，0），（X₂，0，0），（X₃，0，0），（0，Y₁，0），（0，Y₂，0），（0，Y₃，0），（0，0，Z₁），（0，0，Z₂），（0，0，Z₃) And the values of bx, by and a of the photograph taken at each coordinate are obtained using the method of S3, and are substituted into equation (3) to obtain

（4）

A can be obtained by solving equation (4)_x，B_x，C_x，A_y，B_y，C_y，A_z，B_z，C_zA value of (d);

s5, the A obtained in the S4_x，B_x，C_x，A_y，B_y，C_y，A_z，B_z，C_zSubstituting the value of (2) into the equation (3) to obtain the actual coordinates (x, y, z) of the center of the positioning ball (2) relative to the industrial camera (5);

s6, the coordinate of the center of the ball socket of the ball locking device (3) relative to the industrial camera (5) is (x)₀，y₀，z₀) The coordinates are ball locking devices3) A known quantity determined at design time of manufacture, Δ x = x-x₀，Δy=y-y₀，Δz=z-z₀。

3. The visual positioning method for component locking of airplane digital docking according to claim 2, characterized in that: the image processing procedure in S3 is as follows:

1) taking a picture of the positioning ball (2);

2) carrying out binarization on the image, and extracting the edge of the image by using a Canny algorithm;

3) and (5) finding the major axis a and the central point coordinates (bx, by) of the extracted elliptical edge.

4. The visual positioning method for component locking of airplane digital docking according to claim 2, characterized in that: and programming the visual algorithm to image processing and positioning control software, then automatically calculating the amount of movement, driving the numerical control positioner (4) to finish posture adjustment alignment, and lifting and locking the positioning ball (2).

Technical Field

The invention relates to the technical field of airplane assembly, in particular to a part locking visual positioning method for airplane digital docking.

Background

Each large component in the digital docking of the airplane is generally supported by more than 3 positioners, and the support mode adopts the joint connection of a positioning ball and a ball socket of a ball locking device. Each numerical control positioner has the function of moving in three axes of x, y and z which are perpendicular to each other, and the ordered movement of each numerical control positioner can ensure that a large component can complete the posture adjustment of six degrees of freedom in space, and the posture adjustment and the approaching movement of the two large components can realize the digital butt joint of the large components of the airplane. The conventional locator holding ball is judged by human vision, internal stress is released after holding, the holding ball is long in use, and large parts of an airplane are easy to break.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides an industrial camera arranged at the bottom of a ball socket of a ball locking device of a numerical control positioner, after the camera is calibrated, the positioning ball is shot upwards, and through a visual algorithm in a computer, can directly calculate the offset delta x, delta y and delta z of the positioning ball in the directions of x, y and z, a control system in the numerical control positioner converts the offset delta x, delta y and delta z into the movement length in the directions of x, y and z, drives the numerical control positioner to respectively advance the length of delta x and delta y in the directions of x axis and y axis, the ball socket of the ball locking device is aligned with the positioning ball in the direction vertical to the z direction, and then the length of the ball locking device advancing in the z axis direction is controlled, so that the ball locking device of the numerical control positioner receives and locks the positioning ball, three translational degrees of freedom are restrained, and the part locking visual positioning method for the airplane digital butt joint with three rotational degrees of freedom is released. The ball locking device is arranged above the numerical control positioner, and the lengths of ball socket operation delta x, delta y and delta z are completed by driving the numerical control positioner by a motion control system in the numerical control positioner.

The technical scheme for realizing the purpose of the invention is as follows:

a part locking visual positioning method for airplane digital butt joint includes installing a ball locking device on a numerical control positioner, installing a positioning ball on an airplane part, shooting the positioning ball by an industrial camera at the bottom of the ball locking device, calculating deviation delta x, delta y and delta z of the positioning ball relative to a ball socket of the ball locking device through a visual algorithm in a computer, converting the deviation delta x, delta y and delta z into movement lengths in three directions of x, y and z by a control system in the numerical control positioner, driving and controlling the numerical control positioner to respectively advance the length delta x and the length delta y in the directions of the x axis and the y axis to enable the ball locking device to align the positioning ball in the direction vertical to the z direction, and then operating the length delta z in the direction of the z axis to enable the ball locking device to receive and lock the positioning ball so as to complete connection of the airplane part and the numerical control positioner.

The visual algorithm is specifically as follows:

s1, an image formed by shooting a positioning ball by an industrial camera is an ellipse, and according to the pinhole imaging principle,

（1）

x, Y, Z is the coordinate of the sphere center of the positioning sphere in the coordinate system with the optical center of the industrial camera as the origin, f is the focal length of the industrial camera, b_x，b_yThe coordinate of the center of the projection ellipse in the imaging plane is shown as a, the long axis of the ellipse in the picture is shown as D, the diameter of the positioning ball is shown as D, and f is an inherent parameter of the industrial camera, which can be obtained by a standard calibration method.

S2, calculating the coordinates of the sphere center of the positioning sphere as follows:

（2）

s3, processing the image to obtain a and b_x，b_y。

S4, in fact, a picture shot by the industrial camera is deformed and does not completely accord with the pinhole imaging principle, and the following equation can be obtained in consideration of the deformation influence:

（3）

in the formula A_x，B_x，C_x，A_y，B_y，C_y，A_z，B_z，C_zThe unknown number is obtained by calibration, and the calibration process is as follows: the coordinates of the positioning ball in the coordinate system of the industrial camera are respectively taken as (X)₁，0，0），（X₂，0，0），（X₃，0，0），（0，Y₁，0），（0，Y₂，0），（0，Y₃，0），（0，0，Z₁），（0，0，Z₂），（0，0，Z₃) And the values of bx, by and a of the photograph taken at each coordinate are obtained using the method of S3, and are substituted into equation (3) to obtain

（4）

A can be obtained by solving equation (4)_x，B_x，C_x，A_y，B_y，C_y，A_z，B_z，C_zThe value of (c).

S5, the A obtained in the S4_x，B_x，C_x，A_y，B_y，C_y，A_z，B_z，C_zThe actual coordinates (x, y, z) of the center of the sphere (2) of the positioning sphere relative to the industrial camera (5) can be determined by substituting the values into equation (3).

S6, the coordinate of the center of the ball socket of the ball locking device (3) relative to the industrial camera (5) is (x)₀，y₀，z₀) The coordinates are known quantities determined when the ball locking device (3) is designed and manufactured, and delta x = x-x₀，Δy=y-y₀，Δz=z-z₀。

Further, the image processing procedure in S3 is as follows:

1) shooting a picture of the positioning ball;

2) carrying out binarization on the image, and extracting the edge of the image by using a Canny algorithm;

3) and (5) finding the major axis a and the central point coordinates (bx, by) of the extracted elliptical edge.

And programming the visual algorithm to image processing and positioning control software, then automatically calculating the amount of exercise, driving the numerical control positioner to finish posture adjustment and alignment, and lifting and locking the positioning ball.

After the technical scheme is adopted, the invention has the following positive effects:

the invention replaces the visual judgment of a locator for holding the ball, reduces the internal stress of the locked part, prevents the damage of the airplane part, saves the human resource and is convenient to operate and use.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which

FIG. 1 is a general schematic of the present invention;

FIG. 2 is a partial cross-sectional view of the ball locking device of the present invention;

FIG. 3 is a schematic diagram of the imaging principle of the pinhole according to the present invention.

Detailed Description

Referring to fig. 1 and 2, the invention relates to an aircraft component 1, a positioning ball 2, a ball locking device 3, a numerical control positioner 4, an industrial camera 5 and a computer 6; firstly, the ball locking device 3 is arranged on the numerical control positioner 4, secondly, the positioning ball 2 is arranged on the airplane component 1, then the positioning ball 2 is shot by using an industrial camera 5 at the bottom of the ball locking device 3, then wirelessly transmitting to a computer 6, calculating the deviation delta x, delta y and delta z of the positioning ball 2 relative to the ball socket of the ball locking device 3 through a visual algorithm in the computer 6, converting the deviation delta x, delta y and delta z into the movement lengths in the x direction, the y direction and the z direction by a control system in the numerical control positioner 4, driving and controlling the numerical control positioner 4 to respectively advance the lengths of delta x and delta y in the x axis direction and the y axis direction, the ball locking device 3 is aligned to the positioning ball 2 in the vertical z direction, and then the length of delta z is operated in the z axis direction, so that the ball locking device 3 receives the positioning ball 2 and locks, and the connection of the aircraft component 1 and the numerical control positioner 4 is completed.

Referring to fig. 3, the visual algorithm is embodied as follows:

s1, an image formed by shooting a positioning ball 2 by an industrial camera 5 is an ellipse, and according to the pinhole imaging principle,

（1）

wherein X, Y, Z is the coordinate of the sphere center of the positioning sphere 2 in the coordinate system of the positioning sphere 2 with the optical center of the industrial camera 5 as the origin, f is the focal length of the industrial camera 5, b is the focal length of the industrial camera 5_x，b_yThe coordinates of the center of the projected ellipse in the imaging plane, a is the long axis of the ellipse in the photograph, D is the diameter of the positioning sphere 2, and f is an intrinsic parameter of the industrial camera 5, which can be obtained by a standard calibration method.

S2, calculating the coordinates of the sphere center of the positioning sphere 2 as follows:

（2）

s3, processing the image to obtain a and b_x，b_y；

1) Taking a picture of the positioning ball;

2) carrying out binarization on the image, and extracting the edge of the image by using a Canny algorithm;

3) and (5) finding the major axis a and the central point coordinates (bx, by) of the extracted elliptical edge.

S4, in fact, a picture shot by the industrial camera 5 is deformed and does not completely accord with the pinhole imaging principle, and the following equation can be obtained in consideration of the deformation influence:

（3）

in the formula A_x，B_x，C_x，A_y，B_y，C_y，A_z，B_z，C_zThe unknown number is obtained by calibration, and the calibration process is as follows: the coordinates of the positioning ball 2 in the coordinate system of the industrial camera 5 are respectively taken as (X)₁，0，0），（X₂，0，0），（X₃，0，0），（0，Y₁，0），（0，Y₂，0），（0，Y₃，0），（0，0，Z₁），（0，0，Z₂），（0，0，Z₃) And the values of bx, by and a of the photograph taken at each coordinate are obtained using the method of S3, and are substituted into equation (3) to obtain

（4）

A can be obtained by solving equation (4)_x，B_x，C_x，A_y，B_y，C_y，A_z，B_z，C_zThe value of (c).

S5, the A obtained in the S4_x，B_x，C_x，A_y，B_y，C_y，A_z，B_z，C_zThe value of (2) is substituted into equation (3), and the actual coordinates of the center of the sphere of the positioning ball 2 can be obtained.

S6, the coordinate of the center of the ball socket of the ball locking device 3 relative to the industrial camera 5 is (x)₀，y₀，z₀) The coordinates are known quantities determined at the time of design and manufacture of the ball locking device 3, Δ x = x-x₀，Δy=y-y₀，Δz=z-z₀。

And programming a visual algorithm to image processing and positioning control software through a computer, then automatically calculating the amount of exercise, driving the numerical control positioner 4 to finish posture adjustment alignment, and lifting and locking the positioning ball 2.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.