CN110260813B - Bend pipe deflection laser detection method based on CCD image processing - Google Patents

Bend pipe deflection laser detection method based on CCD image processing Download PDF

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CN110260813B
CN110260813B CN201910428701.8A CN201910428701A CN110260813B CN 110260813 B CN110260813 B CN 110260813B CN 201910428701 A CN201910428701 A CN 201910428701A CN 110260813 B CN110260813 B CN 110260813B
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高峰
郭峥璐
郑建明
李艳
刘辰
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Xian University of Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
    • G01B11/27—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes
    • G01B11/272—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes using photoelectric detection means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0025—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings of elongated objects, e.g. pipes, masts, towers or railways
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0075—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by means of external apparatus, e.g. test benches or portable test systems
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/0002—Inspection of images, e.g. flaw detection
    • G06T7/0004—Industrial image inspection
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/70—Determining position or orientation of objects or cameras
    • G06T7/73—Determining position or orientation of objects or cameras using feature-based methods
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/30—Subject of image; Context of image processing
    • G06T2207/30108—Industrial image inspection
    • G06T2207/30164—Workpiece; Machine component

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  • Computer Vision & Pattern Recognition (AREA)
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Abstract

The invention discloses a bend deflection laser detection method based on CCD image processing, which comprises the steps of firstly, installing a laser on a positioning mechanism and placing the laser on one side of a pipe fitting, wherein the positioning mechanism is matched with the outer cylindrical surface of the pipe fitting to ensure that a collimated light beam emitted by the laser is vertical to the end surface of the bend; installing a receiving device consisting of a cross target and a CCD camera in a packaging device, wherein the cross target is coaxial with the CCD camera and is positioned in the focal distance range of the CCD camera, and the outer wall of the cross target is in transition fit with the inner wall of the packaging device to complete the connection of cables among a laser, the CCD camera, an image acquisition card, a computer and a controller; then after the laser beam is stably emitted, the computer controls the CCD camera to collect the target center of the cross target and the imaging light spot of the laser beam on the cross target, and the computer processes the image after collecting the image; and finally calculating the bending deflection and the direction. The invention solves the problems of complex process and poor accuracy of pipe straightness measurement in the prior art.

Description

Bend pipe deflection laser detection method based on CCD image processing
Technical Field
The invention belongs to the technical field of pipe straightness detection, and particularly relates to a bend pipe deflection laser detection method based on CCD image processing.
Background
The pipe structure has the characteristics of high strength and rigidity, material saving and attractive appearance, and has better forming and processing performance. The composite material is widely applied to the fields of aerospace, ships, vehicles, petrochemical industry, buildings, medical instruments, pressure containers and the like so as to meet the development trend and the requirement of industrial components for high strength, light weight and high performance complication. The straightness of the pipe fitting is used as an important geometric parameter of the pipe fitting, and if the straightness cannot meet the use requirement, the product performance of the pipe fitting is influenced, and the use safety of industrial equipment is directly related. The measurement of pipe straightness has two requirements: firstly, the accuracy requirement is that the measurement result must reach a certain credibility; secondly, the method has economic requirement, namely the measuring result is simple and economic on the premise of ensuring the accuracy of the measuring result.
At present, the lever method, the piston method, the laser collimation method and the like are adopted at home and abroad. They are both off-line contact or non-contact measurements and the measurement process is complicated. In recent years, machine vision technology is becoming an important technology for improving production efficiency and guaranteeing product quality in automated production due to development and application of the technology, and the technology is applied to the fields of production detection and processing control in industrially developed countries. The machine vision detection method is non-contact two-dimensional or three-dimensional measurement formed by using a CCD camera as an image sensor and combining the technologies of image processing, artificial intelligence, precision measurement and the like.
Disclosure of Invention
The invention aims to provide a bend pipe deflection laser detection method based on CCD image processing, and solves the problems of complex pipe straightness measurement process and poor accuracy in the prior art.
The invention adopts the technical scheme that a bending deflection laser detection method based on CCD image processing is implemented according to the following steps:
step 1, firstly, a laser is arranged on a positioning mechanism and placed on one side of a pipe fitting, and the positioning mechanism is matched with the outer cylindrical surface of the pipe fitting to ensure that a collimated light beam emitted by the laser is perpendicular to the end surface of a bent pipe;
and 2, mounting a receiving device consisting of the cross target and the CCD camera in the packaging device, wherein the cross target is coaxial with the CCD camera and is positioned in the focal range of the CCD camera, and the outer wall of the receiving device is in transition fit with the inner wall of the packaging device.
Step 3, completing the connection of cables among the laser, the CCD camera, the image acquisition card, the computer and the controller;
step 4, after the laser beam is stably emitted, the computer controls the CCD camera to collect the target center of the cross target and the imaging facula of the laser beam on the cross target, and the computer processes the image after collecting the image;
and 5, calculating the bending deflection and the direction.
The present invention is also characterized in that,
and 2, the cross target is in the focal distance range of the CCD camera, and clear and accurate images are acquired through focusing processing of the CCD camera.
The image processing in the step 4 is specifically implemented according to the following steps:
step 4.1, searching for a target, and obtaining pixel coordinates (u, v) of the cross target by using a search algorithm;
step 4.2, size calibration, namely reading the distance d between the two actual scale marks of the cross target and the pixel distance d between the two scales of the cross target in the corresponding acquired image0D and d0The ratio of (a) to (b) is the length of a unit pixel in the image in the actual physical space;
step 4.3, calculating offset, obtaining the offset (delta x, delta y) of the light spot point from the target center in the actual physical space according to the pixel offset (delta u, delta v) of the light spot point from the target center on the image, and obtaining the linear distance BP of the actual light spot point from the cross target center, namely:
Figure BDA0002068293340000031
step 5 is specifically implemented according to the following steps:
step 5.1, obtaining the transverse coordinate offset delta x and the longitudinal coordinate offset delta y of the central point of the facula, the length of the pipe 2l and the flexibility delta of the pipe fitting in the step 40The relation of (1):
Figure BDA0002068293340000032
step 5.2, substituting the formula (1) into the formula (2) to obtain the bending deflection delta of the bent pipe0；
Step 5.3, calculating the bending direction angle a of the pipe fitting according to the offset (delta x, delta y) of the spot point on the actual physical space from the target center obtained in the step 4:
a＝atan2(Δy,Δx) (3)。
the invention has the advantages that the laser detection method for the bending deflection of the elbow based on the CCD image processing adopts the measuring laser, the divergence angle is small, the service life is long, and the output power and the wavelength can be stably controlled; the receiving device adopts a visual method and has the characteristics of simple structure, non-contact and the like. The CCD camera receives the laser circular spot image, the laser circular spot image is converted into a digital signal by the image acquisition system, the digital signal enters the computer to be subjected to high-efficiency high-quality automatic analysis, the requirement on the size of a measured object is low, and the laser circular spot image analysis system is suitable for being used in factories.
Drawings
FIG. 1 is a working principle diagram of a bending pipe deflection laser detection system based on CCD image processing;
FIG. 2 is a schematic diagram of deflection measurement of a single-radian equal-curvature bent pipe;
fig. 3 is an imaging view of a cross target.
In the figure: 1, e-Ne laser, 2, positioning device, 3, cross target, 4, CCD camera, 5, packaging device.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
The invention relates to a bend pipe deflection laser detection method based on CCD image processing, which is implemented according to the following steps:
step 1, firstly, a laser 1 is arranged on a positioning mechanism 2 and is arranged on one side of a pipe fitting, and the positioning mechanism 2 is matched with the outer cylindrical surface of the pipe fitting to ensure that a collimated light beam emitted by the laser 1 is vertical to the end surface of a bent pipe;
step 2, installing a receiving device consisting of a cross target 3 and a CCD camera 4 in a packaging device 5, wherein the cross target 3 is coaxial with the CCD camera 4 and is positioned in the focal range of the CCD camera 4, the outer wall of the cross target is in transition fit with the inner wall of the packaging device 5, the cross target 3 is positioned in the focal range of the CCD camera 4, and clear and accurate images are acquired through focusing treatment on the CCD camera 4;
step 3, completing the connection of the laser 1, the CCD camera 4, the image acquisition card, the computer and the controller through cables;
step 4, after the laser beam is stably emitted, the computer controls the CCD camera 4 to collect the target center of the cross target 3 and the imaging facula of the laser beam on the cross target 3, the computer processes the image after collecting the image, and the image processing is specifically implemented according to the following steps:
step 4.1, searching for a target, and obtaining pixel coordinates (u, v) of the target of the cross target 3 by using a search algorithm;
step 4.2, size calibration, namely reading the distance d between the two actual scale marks of the cross target 3 and the pixel distance d between the two scales of the cross target 3 in the corresponding collected image0D and d0The ratio of (a) to (b) is the length of a unit pixel in the image in the actual physical space;
step 4.3, calculating offset, obtaining the offset (delta x, delta y) of the light spot point from the target center in the actual physical space according to the pixel offset (delta u, delta v) of the light spot point from the target center on the image, and obtaining the linear distance BP of the actual light spot point from the cross target center, namely:
Figure BDA0002068293340000051
step 5, calculating the bending deflection and the direction, and specifically implementing the following steps:
step 5.1, obtaining the transverse coordinate offset delta x and the longitudinal coordinate offset delta y of the central point of the facula, the length of the pipe 2l and the flexibility delta of the pipe fitting in the step 40The relation of (1):
Figure BDA0002068293340000052
step 5.2, substituting the formula (1) into the formula (2) to obtain the bending deflection delta of the bent pipe0；
Step 5.3, calculating the bending direction angle of the pipe fitting according to the offset (delta x, delta y) between the spot point on the actual physical space and the target center obtained in the step 4a：
a＝atan2(Δy,Δx) (3)。
The invention relates to a bending deflection laser detection method based on CCD image processing, which aims at the deformation detection of small deflection with equal curvature caused by the self weight of a pipe fitting and has the advantages of strong intuition, convenient control, high efficiency, nondestructive automatic detection and the like.
As shown in fig. 1 to 3, the bending deflection laser detection method based on CCD image processing of the present invention has the following working principle:
when the bending deflection of the bent pipe is measured, a He-Ne laser 1 is fixed on one side of the pipe fitting, and a receiving device consisting of a cross target 3 and a CCD camera 4 is arranged on the other side of the pipe fitting. After the laser beam is stabilized, the CCD camera 4 obtains the state image of the light spot position emitted by the laser 1, the image shot by the CCD camera 4 is converted into a numerical image after sampling and quantization through the image acquisition card and is transmitted to a computer, and then the image is processed. Acquiring coordinates of the cross bulls-eye by using a search algorithm to serve as a reference value; and calculating the center coordinates of the target area by extracting the light spot image, and comparing the coordinates with the target area.
When the pipe fitting is not bent, the coordinates of the central pixel of the light spot coincide with the coordinates of the central pixel of the target, namely: BP ═ 0, delta in physical space00; and a is 0 degree. When the pipe fitting is bent, as shown in fig. 2, the center of the light spot deviates from the center of the target in the actual physical space, and the deviation position of the light spot has a corresponding geometric relationship with the initial deflection and the bending direction of the pipe fitting. Therefore, the bending deflection delta of the pipe can be calculated by acquiring the pixel coordinates of the center of the facula and the pixel coordinates of the cross target in the acquired image, converting the pixel offset into the offset BP of the actual physical space according to the size calibration and driving the formula (1), the formula (2) and the formula (3)0And a bend direction angle.
The laser detection method for the bending deflection of the bent pipe based on the CCD image processing can obtain the bending direction and the deflection of the pipe with single-radian bending and equal bending curvature, and can be used for rapid and nondestructive detection of the straightness of the pipeline.

Claims (2)

1. A bend pipe deflection laser detection method based on CCD image processing is characterized by comprising the following steps:
step 1, firstly, a laser (1) is arranged on a positioning mechanism (2) and is arranged on one side of a pipe fitting, and the positioning mechanism (2) is matched with the outer cylindrical surface of the pipe fitting to ensure that a collimated light beam emitted by the laser (1) is perpendicular to the end surface of a bent pipe;
step 2, installing a receiving device consisting of a cross target (3) and a CCD camera (4) in a packaging device (5), wherein the cross target (3) is coaxial with the CCD camera (4) and is positioned in the focal range of the CCD camera (4), and the outer wall of the cross target is in transition fit with the inner wall of the packaging device (5);
step 3, completing the connection of cables among the laser (1), the CCD camera (4), the image acquisition card, the computer and the controller;
step 4, after the laser beam is stably emitted, the CCD camera (4) is controlled by the computer to collect the target center of the cross target (3) and the imaging light spot of the laser beam on the cross target (3), the computer processes the image after collecting the image, and the image processing in the step 4 is specifically implemented according to the following steps:
step 4.1, searching for a target, and obtaining pixel coordinates (u, v) of the target of the cross target (3) by using a search algorithm;
step 4.2, size calibration, namely reading the distance d between the two actual scale marks of the cross target (3) and the pixel distance d between the two scales of the cross target (3) in the corresponding acquired image0D and d0The ratio of (a) to (b) is the length of a unit pixel in the image in the actual physical space;
step 4.3, calculating offset, obtaining the offset (delta x, delta y) of the light spot point from the target center in the actual physical space according to the pixel offset (delta u, delta v) of the light spot point from the target center on the image, and obtaining the linear distance BP of the actual light spot point from the cross target center, namely:
Figure FDA0002855022520000021
step 5, calculating the deflection and the direction of the bent pipe, wherein the step 5 is implemented according to the following steps:
step 5.1, obtaining the beam of the light spot central point from the step 4Coordinate offset delta x, longitudinal coordinate offset delta y, pipe length 2l and bent pipe deflection delta0The relation of (1):
Figure FDA0002855022520000022
step 5.2, substituting the formula (1) into the formula (2) to obtain the bending deflection delta of the bent pipe0；
Step 5.3, calculating the bending direction angle a of the pipe fitting according to the offset (delta x, delta y) of the spot point on the actual physical space from the target center obtained in the step 4:
a＝atan2(Δy/Δx) (3)。
2. the laser detection method for elbow deflection based on CCD image processing according to claim 1, characterized in that in step 2, the cross target (3) is within the focal distance range of the CCD camera (4), and a clear and accurate image is acquired through the focusing processing of the CCD camera (4).
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CN113706489B (en) * 2021-08-18 2024-05-28 珠海格力智能装备有限公司 Elbow splicing processing method and device, storage medium and elbow splicing equipment
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