CN115585736A

CN115585736A - Internal thread tooth form geometric parameter measuring method and device based on binocular vision

Info

Publication number: CN115585736A
Application number: CN202110692282.6A
Authority: CN
Inventors: 刘大猛; 胡香敏
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2023-01-10
Anticipated expiration: 2041-06-22
Also published as: CN115585736B

Abstract

The invention discloses a binocular vision-based internal thread tooth form geometric parameter measuring method and device, wherein the method comprises the steps of utilizing an endoscope probe to shoot a first group of internal thread local images in a stepping mode at a first preset shooting angle according to stepping length, and shooting a second group of internal thread local images in a stepping mode at a second preset shooting angle; determining a first internal thread image and a light and dark stripe width of the binaryzation light and dark stripe width of a second internal thread image; determining tooth form image parameters of the internal thread by utilizing the corresponding relation between the tooth form stripe width and the tooth form image parameters at a shooting angle according to the first internal thread image and the binaryzation light and dark stripe width of the second internal thread image; and determining the actual tooth form parameters of the internal thread according to the tooth form image parameters and the pitch length of the internal thread. The invention utilizes the endoscope probe to shoot the internal thread image, and realizes the measurement of the small-size deep hole of the internal thread; and the statistical average is carried out along the trend of the internal thread, so that the measurement precision of the thread form parameters of the internal thread is improved.

Description

Internal thread tooth form geometric parameter measuring method and device based on binocular vision

Technical Field

The invention relates to the technical field of thread vision detection, in particular to a method and a device for measuring geometric parameters of an internal thread profile based on binocular vision.

Background

This section is intended to provide a background or context to the embodiments of the invention that are recited in the claims. The description herein is not admitted to be prior art by inclusion in this section.

The quality detection of the internal thread is important to the industrial fields of mechanical fastening, sealing, high-precision transmission and the like, and the detection items mainly involved comprise the detection of surface appearance defects, form and position tolerances, geometric parameters and the like of the internal thread. At present, contact type measuring methods are still widely used in the industrial field, and comprise a thread go-no-go gauge, a micrometer and a measuring needle scanning detection method. In recent years, with the development of industrial intelligence, industrial quality inspection is moving towards a nondestructive and rapid non-contact measurement method. At present, methods such as an industrial microscope, an eddy current inspection, a laser inspection, a machine vision and the like are adopted for non-contact inspection. Machine vision inspection techniques have been primarily used in the field of thread inspection. For external threads, a photograph is usually taken of the thread flank using back illumination, and the geometric parameters of the tooth form are obtained by image processing; for the internal thread, the best existing technology is to use laser-line illumination, a camera shoots a wavy bright line on the thread from a specific angle, and the thread profile geometric parameters of the internal thread are calculated based on the trigonometry measurement principle.

The traditional contact type measurement can only measure one section of the internal thread, and cannot obtain full-size measurement; in addition, in a large amount of industrial quality tests, the quality of threads can only be checked qualitatively and randomly through thread passing and stopping rules, and all threads cannot be detected accurately and quantitatively, so that the traditional contact type measurement is complex in work and low in efficiency. However, the existing thread visual detection technology is complex in equipment, cannot penetrate into an inner hole by illumination, and is difficult to detect the thread form of the internal thread of a small-size deep hole.

Disclosure of Invention

The embodiment of the invention provides an internal thread profile geometric parameter measuring method based on binocular vision, which is used for measuring internal thread profile geometric parameters and small-size deep holes and comprises the following steps:

using an endoscope probe to respectively take a first group of internal thread local images in a stepping mode at a first preset shooting angle and a second group of internal thread local images in a stepping mode at a second preset shooting angle according to the stepping length;

respectively determining the binaryzation bright-dark stripe width of the first internal thread image with the bright-dark stripe width and the binaryzation bright-dark stripe width of the second internal thread image with the bright-dark stripe width; the first internal thread image is formed by splicing a first group of internal thread local images, and the second internal thread image is formed by splicing a second group of internal thread local images;

determining the tooth form image parameters of the internal thread by utilizing the projection relation between the tooth form stripe width of the internal thread and the tooth form image parameters of the internal thread under a shooting angle according to the binaryzation bright and dark stripe width of the first internal thread image and the binaryzation bright and dark stripe width of the second internal thread image;

and determining the actual tooth form parameters of the internal thread according to the tooth form image parameters and the pitch length of the internal thread.

The embodiment of the invention also provides an internal thread tooth form geometric parameter measuring device based on binocular vision, which is used for realizing the measurement of the internal thread tooth form geometric parameters and small-size deep holes, and comprises:

the local image shooting module is used for shooting a first group of internal thread local images in a stepping mode at a first preset shooting angle and shooting a second group of internal thread local images in a stepping mode at a second preset shooting angle according to the stepping length by using the endoscope probe;

the stripe width determining module is used for respectively determining the binaryzation bright and dark stripe width of the first internal thread image with the bright and dark stripe width and the binaryzation bright and dark stripe width of the second internal thread image with the bright and dark stripe width; the first internal thread image is formed by splicing a first group of internal thread local images, and the second internal thread image is formed by splicing a second group of internal thread local images;

the image parameter determining module is used for determining the tooth form image parameters of the internal thread according to the binaryzation light and shade stripe width of the first internal thread image and the binaryzation light and shade stripe width of the second internal thread image by utilizing the projection relation between the tooth form stripe width of the internal thread and the tooth form image parameters of the internal thread under the shooting angle;

and the thread form parameter determining module is used for determining actual thread form parameters of the internal thread according to the thread form image parameters and the thread pitch length of the internal thread.

The embodiment of the invention also provides computer equipment which comprises a memory, a processor and a computer program which is stored on the memory and can run on the processor, wherein the processor executes the computer program to realize the internal thread tooth geometry parameter measuring method based on the binocular vision.

An embodiment of the present invention further provides a computer-readable storage medium, which stores a computer program for executing the above binocular vision-based internal thread geometric parameter measurement method.

In the embodiment of the invention, an endoscope probe is utilized to respectively take a first group of internal thread local images in a stepping mode at a first preset taking angle and take a second group of internal thread local images in a stepping mode at a second preset taking angle according to the stepping length; respectively determining the binaryzation bright-dark stripe width of the first internal thread image with the bright-dark stripe width and the binaryzation bright-dark stripe width of the second internal thread image with the bright-dark stripe width; determining the tooth form image parameters of the internal thread by utilizing the projection relation between the tooth form stripe width of the internal thread and the tooth form image parameters of the internal thread under a shooting angle according to the binaryzation bright and dark stripe width of the first internal thread image and the binaryzation bright and dark stripe width of the second internal thread image; and determining the actual tooth form parameters of the internal thread according to the tooth form image parameters and the pitch length of the internal thread. According to the embodiment of the invention, the endoscope probe is used for shooting the image of the internal thread, so that the measurement of the small-size deep hole of the internal thread is realized; and the statistics is average along the trend of the internal thread, the credible tooth form parameters can still be obtained for the thread defects, and the measurement precision of the internal thread tooth form parameters is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts. In the drawings:

FIG. 1 is a flowchart of an implementation of a binocular vision-based method for measuring geometric parameters of internal thread profiles according to an embodiment of the present invention;

FIG. 1-1 is a schematic view of a camera for capturing internal threads provided by an embodiment of the present invention;

fig. 1-2 are schematic views of partial images of internal threads at certain viewing angles according to embodiments of the present invention;

fig. 1-3 are schematic views of partial images of an internal thread at a shooting angle greater than 0 ° according to an embodiment of the present invention;

fig. 1 to 4 are schematic views of partial images of an internal thread when a shooting angle is less than 0 ° according to an embodiment of the present invention;

fig. 1 to 5 are schematic diagrams illustrating a correspondence relationship between a thread pattern stripe width of an internal thread and a thread pattern image parameter of the internal thread according to an embodiment of the present invention;

fig. 2 is a flowchart illustrating the implementation of step 101 in the binocular vision-based method for measuring geometric parameters of internal thread forms according to the present invention;

fig. 3 is a flowchart illustrating the implementation of step 102 in the binocular vision-based internal thread geometric parameter measurement method according to the embodiment of the present invention;

FIG. 4 is a flowchart illustrating the implementation of step 103 in the binocular vision-based method for measuring geometric parameters of internal thread forms according to the present invention;

fig. 5 is a flowchart illustrating the implementation of step 104 in the binocular vision-based method for measuring geometric parameters of internal thread forms according to an embodiment of the present invention;

FIG. 6 is a functional block diagram of an apparatus for measuring geometric parameters of internal thread profile based on binocular vision according to an embodiment of the present invention;

fig. 7 is a block diagram of a local image capturing module 601 in the binocular vision-based internal thread tooth geometry parameter measuring apparatus according to the embodiment of the present invention;

fig. 8 is a block diagram illustrating a structure of a stripe width determining module 602 in the binocular vision-based internal thread tooth geometry parameter measuring apparatus according to the embodiment of the present invention;

fig. 9 is a structural block diagram of an image parameter determining module 603 in the binocular vision-based internal thread geometric parameter measuring apparatus according to the embodiment of the present invention;

fig. 10 is a block diagram illustrating a thread form parameter determining module 604 of the binocular vision-based internal thread form geometric parameter measuring apparatus according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention, but not to limit the present invention.

Fig. 1 shows a flow of implementing the binocular vision-based internal thread geometric parameter measurement method provided by the embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and detailed descriptions are as follows:

as shown in fig. 1, the binocular vision-based internal thread tooth form geometric parameter measuring method includes:

step 101, using an endoscope probe to respectively take a first group of internal thread local images in a stepping mode at a first preset taking angle and a second group of internal thread local images in a stepping mode at a second preset taking angle according to stepping lengths;

step 102, determining the binaryzation bright and dark stripe width of a first internal thread image with the bright and dark stripe width and the binaryzation bright and dark stripe width of a second internal thread image with the bright and dark stripe width respectively; the first internal thread image is formed by splicing a first group of internal thread local images, and the second internal thread image is formed by splicing a second group of internal thread local images;

103, determining tooth pattern image parameters of the internal thread by utilizing a projection relation between the tooth pattern stripe width of the internal thread and the tooth pattern image parameters of the internal thread at a shooting angle according to the binarization bright and dark stripe width of the first internal thread image and the binarization bright and dark stripe width of the second internal thread image;

and step 104, determining the actual tooth form parameters of the internal thread according to the tooth form image parameters and the pitch length of the internal thread.

When measuring the geometric parameters of the internal thread, the internal thread can be shot by using an endoscope probe. Generally speaking, the internal thread hole is relatively small, the small-diameter endoscope probe only needs to be manufactured for the small threaded hole to realize the measurement of the geometric parameters of the small-diameter internal thread, and the laser-linear line is used for shooting at a variable angle outside the threaded hole after the projection outside the screw inner hole, so that the measurement of the geometric parameters of the small-diameter internal thread cannot be realized. Fig. 1-1 shows an internal thread shooting schematic provided by an embodiment of the present invention, when an endoscope probe is used to shoot an internal thread, a first group of local images of the internal thread are shot in a stepping manner at a first preset shooting angle α 1 according to a stepping length, and then a second group of local images of the internal thread are shot in a stepping manner at a second preset shooting angle α 2 according to the stepping length. Fig. 1-2 show a schematic view of a local image of an internal thread at a certain viewing angle provided by an embodiment of the present invention, and it can be seen from fig. 1-2 that the intensity of reflected light is high and the intensity of reflected light on the tooth flank is low because the tooth crest and the tooth flank are nearly perpendicular to the direction of incident light, and the local image of the internal thread is actually represented as stripes with alternate light and dark. The bending direction of the bright and dark stripes is shown in fig. 1-3 and fig. 1-4 according to the difference between the shooting angle and the size relationship of 0 °. Fig. 1 to 3 show partial image representations of the internal thread at a shooting angle greater than 0 °, and fig. 1 to 4 show partial image representations of the internal thread at a shooting angle less than 0 °.

In a preferred embodiment, in order to improve the accuracy of capturing the internal thread image and further improve the measurement accuracy of the internal thread geometric parameters, the step length is set according to the number of threads included in the captured internal thread local image. If the internal thread comprises N threads and the step length progress is set to be M, the number of the threads contained in the shot internal thread local image is N/M, and the step length progress M is set on the basis that the step length progress M and the number of the threads contained in the internal thread local image are integers as much as possible. The specific value of the step length progress may be specifically set according to the number of the thread bars and the number of the thread bars included in the shot internal thread local image, which is not particularly limited in the embodiment of the present invention.

In a preferred embodiment, in order to further improve the measurement accuracy of the geometric parameter of the internal thread, the first preset shooting angle α 1 and the second preset shooting angle α 2 are the same in angle and opposite in direction. When the first preset shooting angle α 1 and the second preset shooting angle α 2 are set, the first preset shooting angle α 1 and the second preset shooting angle α 2 are preferably used, that is, the first preset shooting angle α 1 is the same as the second preset shooting angle α 2, and the directions are opposite. First preset shooting angle alpha 1 and second preset shooting angle alpha 2 are symmetrical, can promote as far as possible and detect the internal thread geometric parameters measuring precision under the prerequisite of avoiding the angle to shelter from, reduce the influence of angle error.

In a preferred embodiment, in order to improve the accuracy of the internal thread image stitching and further improve the accuracy of the internal thread geometric parameter measurement, the overlapping portion of two adjacent frames of internal thread local images in the first set of internal thread local images is smaller than the thread pitch of the internal thread, and the overlapping portion of two adjacent frames of internal thread local images in the second set of internal thread local images is smaller than the thread pitch of the internal thread. The overlapping part of two adjacent frames of internal thread local images in the internal thread local image is smaller than the thread pitch of the internal thread, so that the internal thread local images can be spliced conveniently, the accuracy of splicing the internal thread images is improved, and the accuracy of measuring the geometric parameters of the internal thread is further improved.

In a preferred embodiment, in order to further improve the measurement accuracy of the geometric parameter of the internal thread, the sum of the flank angle of the internal thread and the absolute value of the first preset shooting angle α 1 is not more than 90 °, and the sum of the flank angle of the internal thread and the absolute value of the second preset shooting angle α 2 is not more than 90 °. The first preset shooting angle alpha 1 and the second preset shooting angle alpha 2 are symmetrical as much as possible, and in order to avoid that the visual angle of the endoscope probe deviates from the side surface direction of the thread to the greatest extent and two tooth sides are shielded during imaging, the sum of the tooth side angle and the shooting angle is not more than 90 degrees. For example, the internal thread with a flank angle of 60 ° may select the first predetermined photographing angle α 1 and the second predetermined photographing angle α 2 to be 20 ° and-20 ° respectively during photographing.

In a preferred embodiment, in order to facilitate the switching of the view angle of the endoscope probe and further improve the measurement accuracy of the geometric parameters of the internal thread, the variable angle plane reflecting mirror of the endoscope probe comprises two limiting angles, and the view angle of the variable angle plane reflecting mirror of the endoscope probe is switched through the link mechanism. The variable angle range of the variable angle plane reflecting mirror of the endoscope probe is limited by the two limit angles, and meanwhile, the visual angle of the variable angle plane reflecting mirror of the endoscope probe is conveniently switched by utilizing the connecting rod mechanism, so that the measurement precision of the geometric parameters of the internal thread is further improved.

After a first group of internal thread local images and a second group of internal thread local images are respectively shot by using an endoscope probe, the first group of internal thread local images are spliced to form a first internal thread image, the second group of internal thread local images are spliced to form a second internal thread image, and then the binaryzation light and dark stripe width of the first internal thread image and the binaryzation light and dark stripe width of the second internal thread image with the light and dark stripe width are respectively determined through image processing.

After the binaryzation bright-dark stripe width of the first internal thread image with the bright-dark stripe width and the binaryzation bright-dark stripe width of the second internal thread image with the bright-dark stripe width are obtained respectively, the tooth form image parameters of the internal threads are determined by utilizing the projection relation between the tooth form image parameters of the internal threads and the stripe widths under the shooting angle. Fig. 1 to 5 are schematic diagrams illustrating correspondence between a thread pattern stripe width of an internal thread and a thread pattern image parameter of the internal thread provided by an embodiment of the present invention. As can be seen from FIGS. 1-5, there is a specific projection relationship between the stripe width of the internal thread, the photographing angle and the tooth pattern image parameters of the internal thread. Therefore, the projection relationship shown in FIGS. 1-5 can be used to determine the tooth-shape image parameters of the internal thread based on the binary bright-dark stripe width. Tooth form image parameters defined by the binaryzation bright-dark stripe width of the first internal thread width first internal thread image, the binaryzation bright-dark stripe width of the second internal thread image, the binaryzation bright-dark stripe width of the first internal thread image, the binaryzation bright-dark stripe width of the second internal thread image comprise Ll, lt, lr, ld and Lh which respectively represent image parameters of the left tooth side, the crest, the right tooth side, the root and the tooth height of the internal thread and mean the pixel width of each part of the tooth form after projection transformation.

Wherein, the relationship between the tooth-pattern stripe width (Ll ', lt', lr ', and Ld') of the internal thread and the tooth-pattern image parameters (Ll, lt, lr, ld, lh) of the internal thread can be expressed by the following formula:

Ll'＝(Ll-Lh×tan(α))×cos(α)；Lt'＝Lt×cos(α)；

Lr'＝(Lr+Lh×tan(α))×cos(α)；Ld'＝Ld×cos(α)；

wherein, ll ', lt', lr 'and Ld' respectively represent the left flank stripe width, the crest stripe width, the right flank stripe width and the root stripe width of the internal thread; ll, lt, lr and Ld respectively represent left flank image parameters, crest image parameters, right flank image parameters and root image parameters of the internal thread, and Lh represents tooth height image parameters of the internal thread; alpha is a shooting angle.

The tooth form image parameters and the tooth form actual parameters are simple proportional relations, a proportionality coefficient a represents the actual length of a millimeter corresponding to one pixel in a picture, and the proportionality coefficient a can be calculated by utilizing a thread pitch, because the thread pitch length L corresponds to the sum of the tooth bottom, left tooth side, tooth top and right tooth side image parameters of one tooth form: l = a × (Ld + Ll + Lt + Lr)

Therefore, when the thread form image parameter of the internal thread is determined, the proportionality coefficient between the thread form image parameter and the thread form actual parameter is determined based on the thread pitch length L and the sum of the thread form, left thread side, thread top and right thread side image parameters of the thread form, and the thread form actual parameter of the internal thread is determined based on the thread form image parameter and the proportionality coefficient.

In the embodiment of the invention, an endoscope probe is utilized to respectively take a first group of local images of the internal thread in a stepping mode at a first preset shooting angle and take a second group of local images of the internal thread in a stepping mode at a second preset shooting angle according to the stepping length; respectively determining the binaryzation bright-dark stripe width of the first internal thread image with the bright-dark stripe width and the binaryzation bright-dark stripe width of the second internal thread image with the bright-dark stripe width; determining the tooth form image parameters of the internal thread by utilizing the corresponding relation between the tooth form stripe width of the internal thread and the tooth form image parameters of the internal thread under a shooting angle according to the binaryzation bright and dark stripe width of the first internal thread image and the binaryzation bright and dark stripe width of the second internal thread image; and determining the actual parameters of the thread form according to the thread form image parameters and the thread pitch length of the internal thread.

According to the embodiment of the invention, the endoscope probe is used for shooting the image of the internal thread, so that the measurement of the small-size deep hole of the internal thread is realized; and the statistics is average along the trend of the internal thread, the credible tooth form parameters can still be obtained for the thread defects, and the measurement precision of the internal thread tooth form parameters is improved.

Fig. 2 shows a flow of implementing step 101 in the binocular vision-based internal thread geometric parameter measurement method provided by the embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and the detailed description is as follows:

in one embodiment of the invention, the head of the endoscopic probe is fitted with a variable angle plane mirror. In order to improve the shooting accuracy of the local images of the internal thread and further improve the measurement accuracy of the geometric parameters of the internal thread, as shown in fig. 2, step 101, using an endoscope probe to respectively shoot a first group of local images of the internal thread at a first preset shooting angle step by step and a second group of local images of the internal thread at a second preset shooting angle step by step according to the step length includes:

step 201, shooting a first group of local images of the internal thread from the initial position to the end position of the internal thread in a stepping mode at a first preset shooting angle according to the stepping length by using an endoscope probe with a variable-angle plane reflecting mirror mounted on the head; the first preset shooting angle is an acute angle included angle formed by the intersection of a reflection light plane on a variable angle plane reflector of the endoscope probe and a vertical middle axial plane of the internal thread along a first incident light plane from the initial position to the final position of the horizontal middle axial plane of the internal thread, and the included angle formed by the first incident light plane and a normal plane of the variable angle plane reflector is an acute angle;

step 202, shooting a second group of local images of the internal thread from the termination position to the initial position of the internal thread in a stepping mode at a second preset shooting angle according to stepping length by using an endoscope probe with a variable-angle plane reflecting mirror mounted on the head; the second preset shooting angle is an acute angle included angle formed by the intersection of a reflection light plane of a second incident light plane from the termination position to the starting position of the horizontal middle axial plane of the internal thread on a variable angle plane reflector of the endoscope probe and the vertical middle axial plane of the internal thread; the included angle between the second incident light plane and the normal plane of the variable angle plane reflector is an acute angle.

The head of the endoscope probe is provided with a variable angle plane reflector, and the angle of the plane reflector can be changed to adjust the shooting angle (visual angle) of the variable angle plane reflector of the endoscope probe. Referring to fig. 1-2, when an endoscope probe is used to capture a first group of local images of internal threads and a second group of local images of internal threads, the angle of the variable angle plane mirror at the head of the endoscope probe is adjusted, and the first preset capturing angle α 1 is used to capture the first group of local images of internal threads by stepping from the start position to the end position of the internal threads according to the set stepping length. The first preset shooting angle alpha 1 is an acute angle included angle formed by the intersection of a reflection light plane on a variable angle plane reflector of the endoscope probe and a vertical middle axial plane of the internal thread along a first incident light plane from the starting position to the ending position of the horizontal middle axial plane of the internal thread. The included angle between the first incident light plane and the normal plane of the variable angle plane reflector is an acute angle.

Then, the angle of the variable-angle plane mirror of the head of the endoscope probe is adjusted, and the step shooting is started from the ending position of the internal thread to the starting position at a second preset shooting angle alpha 2 according to the set step length, so that a second group of local images of the internal thread are obtained. The second preset shooting angle alpha 2 is an acute angle included angle formed by the intersection of a reflection light plane of a second incident light plane from the termination position to the starting position of the horizontal middle axial plane of the internal thread on the variable-angle plane reflector of the endoscope probe and the vertical middle axial plane of the internal thread. Namely, the first preset shooting angle α 1 is symmetrical to the second preset shooting angle α 2. And the included angle between the second incident light plane and the normal plane of the variable angle plane reflector is an acute angle.

In the embodiment of the invention, an endoscope probe with a variable-angle plane reflector mounted on the head is used for shooting a first group of local images of the internal thread in a stepping mode from the starting position to the ending position of the internal thread at a first preset shooting angle alpha 1 according to the stepping length; the first preset shooting angle alpha 1 is an acute angle included angle formed by the intersection of a reflecting light plane of a first incident light plane from the initial position to the final position of the horizontal middle axial plane of the internal thread on a variable-angle plane reflector of an endoscope probe and the vertical middle axial plane of the internal thread; and step-shooting a second group of local images of the internal thread from the termination position to the starting position of the internal thread by a second preset shooting angle alpha 2 according to the step length by utilizing the endoscope probe with the head provided with the variable-angle plane reflector, wherein the second preset shooting angle alpha 2 is an acute angle included angle formed by the intersection of a reflection light plane of a second incident light plane from the termination position to the starting position of the horizontal middle axial plane of the internal thread on the variable-angle plane reflector of the endoscope probe and the vertical middle axial plane of the internal thread. In the embodiment of the invention, the first preset shooting angle alpha 1 and the second preset shooting angle alpha 2 are symmetrical, so that the local image shooting accuracy of the internal thread can be improved, and the measurement precision of the geometric parameters of the internal thread is further improved.

Fig. 3 illustrates a flow of implementing step 102 in the binocular vision-based internal thread geometric parameter measurement method provided by the embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and the detailed description is as follows:

in an embodiment of the present invention, in order to improve the accuracy of determining the stripe width and further improve the precision of the geometric parameters of the internal thread, as shown in fig. 3, step 102 is to determine the binary bright and dark stripe width of the first internal thread image with the bright and dark stripe width and the binary bright and dark stripe width of the second internal thread image with the bright and dark stripe width, respectively; the first internal thread image is formed by splicing a first group of internal thread local images, and the second internal thread image is formed by splicing a second group of internal thread local images, and the method comprises the following steps:

step 301, respectively splicing the first group of internal thread local images to form a first internal thread image, and splicing the second group of internal thread local images to form a second internal thread image;

step 302, extracting the binarization bright and dark stripes of the first internal thread image and the binarization bright and dark stripes of the second internal thread image by using self-adaptive thresholds respectively;

step 303, respectively carrying out noise reduction on the extracted binarization bright and dark stripes of the first internal thread image and the extracted binarization bright and dark stripes of the second internal thread image through mean value fuzzy and closed operations to obtain the binarization bright and dark stripes of the first internal thread image and the binarization bright and dark stripes of the second internal thread image after noise reduction;

and 304, segmenting and marking the denoised binary bright-dark stripes of the first internal thread image and the denoised binary bright-dark stripes of the second internal thread image by using morphological image processing respectively, and determining the width of the binary bright-dark stripes of the first internal thread image and the width of the binary bright-dark stripes of the second internal thread image.

When the width of the binaryzation bright and dark stripes of the internal thread image is determined, the first group of internal thread local images are spliced to form a first internal thread image, the second group of internal thread local images are spliced to form a second internal thread image, the binaryzation bright and dark stripes of the first internal thread image are extracted by using the self-adaptive threshold, and the binaryzation bright and dark stripes of the second internal thread image are extracted by using the self-adaptive threshold.

In view of the fact that certain noise exists in the binarization bright and dark stripes, in order to further improve the accuracy of determining the stripe width and improve the precision of the geometric parameters of the internal threads, the extracted binarization bright and dark stripes of the first internal thread image and the extracted binarization bright and dark stripes of the second internal thread image are subjected to noise reduction treatment through mean value blurring and closed operation respectively, so that the binarization bright and dark stripes of the first internal thread image and the binarization bright and dark stripes of the second internal thread image after noise reduction are obtained.

Finally, the binaryzation bright and dark stripes of the first internal thread image after noise reduction are cut and marked by using morphological image processing respectively, and the width of the binaryzation bright and dark stripes of the first internal thread image is determined; and utilizing morphological image processing to cut and mark the binarized bright and dark stripes of the second internal thread image after noise reduction, and determining the width of the binarized bright and dark stripes of the second internal thread image.

In the embodiment of the invention, a first group of internal thread local images are respectively spliced to form a first internal thread image, a second group of internal thread local images are spliced to form a second internal thread image, the binaryzation bright and dark stripes of the first internal thread image and the binaryzation bright and dark stripes of the second internal thread image are respectively extracted by using an adaptive threshold, the extracted binaryzation bright and dark stripes of the first internal thread image and the extracted binaryzation bright and dark stripes of the second internal thread image are subjected to noise reduction through mean value blurring and closing operation respectively, the binaryzation bright and dark stripes of the first internal thread image and the binaryzation bright and dark stripes of the second internal thread image after noise reduction are obtained, the binaryzation bright and dark stripes of the first internal thread image and the binaryzation bright and dark stripes of the second internal thread image after noise reduction are respectively cut and marked by using morphological image processing, and the binaryzation bright and dark stripe width of the first internal thread image and the binaryzation bright and dark stripe width of the second internal thread image are determined. According to the embodiment of the invention, the binaryzation light and shade stripes of the internal thread image are extracted by using the self-adaptive threshold, the binaryzation light and shade stripes of the internal thread image are denoised through mean value blurring and closing operation, and finally the binaryzation light and shade stripe width of the internal thread image is determined by using morphological image processing, so that the accuracy of determining the stripe width can be improved, and the precision of the internal thread geometric parameters is further improved.

Fig. 4 shows a flow of implementing step 103 in the binocular vision-based internal thread geometric parameter measurement method provided by the embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and the detailed description is as follows:

in an embodiment of the present invention, in order to improve the accuracy of determining the width of the internal thread profile stripe and further improve the measurement accuracy of the internal thread geometric parameter, as shown in fig. 4, step 103 is performed to determine the profile image parameter of the internal thread by using the projection relationship between the profile stripe width of the internal thread and the profile image parameter of the internal thread at the shooting angle according to the binarized bright and dark stripe width of the bright and dark stripe width first internal thread image and the binarized bright and dark stripe width of the bright and dark stripe width second internal thread image, and includes:

step 401, aligning the binarization bright and dark stripes of the first internal thread image and the binarization bright and dark stripes of the second internal thread image at the starting position or the ending position of the internal thread to obtain a plurality of groups of first thread tooth type stripe width sequences of the first internal thread image which correspond to a first preset shooting angle and take a plurality of stripes as a group and a plurality of groups of second thread tooth type stripe width sequences of the second internal thread image which correspond to a second preset shooting angle and take a plurality of stripes as a group;

step 402, determining a first thread pattern image parameter and a second thread pattern image parameter of the internal thread according to the multiple groups of first thread pattern stripe width sequences and the multiple groups of second thread pattern stripe width sequences by using a projection relation between the thread pattern stripe width of the internal thread and the thread pattern image parameter of the internal thread under a shooting angle.

When the tooth form image parameters of the internal threads are determined specifically, aligning the binaryzation bright and dark stripes of the first internal thread image and the binaryzation bright and dark stripes of the second internal thread image at the initial position or the end position of the internal threads so as to keep the data consistent. And obtaining a plurality of groups of first thread tooth type stripe width sequences of the first internal thread image which corresponds to the first preset shooting angle alpha 1 and takes the plurality of stripes as a group, and a plurality of groups of second thread tooth type stripe width sequences of the second internal thread image which corresponds to the second preset shooting angle alpha 2 and takes the plurality of stripes as a group. For example, the binarization bright and dark stripes of the first internal thread image and the binarization bright and dark stripes of the second internal thread image are aligned at the starting position of the internal thread to obtain a first thread tooth type stripe width sequence { [ Ll ', lt ', lr ', ld { ' of the first internal thread image with a plurality of groups of 4 stripes as a group '] _i }. Wherein, ll ', lt', lr 'and Ld' respectively represent a first left flank image stripe width, a first crest image stripe width, a first right flank image stripe width and a first root image stripe width of the ith group of first internal thread images. And a second thread tooth type stripe width sequence of a second internal thread image with a plurality of groups of 4 stripes as a group { [ Ll ", lt", lr ", ld"] _i }. WhereinAnd Ll ', lt', lr 'and Ld' respectively represent the second left flank image stripe width, the second crest image stripe width, the second right flank image stripe width and the second root image stripe width of the ith group of second internal thread images.

Further, using the correspondence between the thread streak width of the internal thread and the thread pattern image parameter of the internal thread at the shooting angle shown in fig. 1 to 5, the thread pattern image parameter of the internal thread is determined by the following formula:

or

Or

Or

Or

Or

Wherein, ll, lt, lr and Ld respectively represent left flank image parameters, crest image parameters, right flank image parameters and root image parameters of the internal thread; ll ", lt", lr ", and Ld" respectively represent a second left flank image stripe width, a second crest image stripe width, a second right flank image stripe width, and a second root image stripe width of the second internal thread image; ll ', lt', lr 'and Ld' respectively represent the width of a first left tooth side image stripe, the width of a first crest image stripe, the width of a first right tooth side image stripe and the width of a first bottom tooth image stripe of the ith group of first internal thread images, and Lh represents a tooth height image parameter; α 1 and α 2 respectively represent a first preset shooting angle and a second preset shooting angle, and θ l and θ r respectively represent a left flank angle and a right flank angle of the internal thread.

The first tooth form image parameter and the second tooth form image parameter of the internal thread are determined to improve the accuracy of determining the width of the tooth form stripe of the internal thread so as to improve the measurement precision of the geometric parameter of the internal thread, and the average value of two formulas of Ld, ll, lt, lr and h can be used as the tooth form image parameter of the internal thread.

In the embodiment of the invention, the binaryzation bright and dark stripes of the first internal thread image and the binaryzation bright and dark stripes of the second internal thread image are aligned at the starting position or the ending position of the internal thread to obtain a plurality of groups of first thread tooth type stripe width sequences of the first internal thread image which correspond to a first preset shooting angle and take a plurality of groups of stripes as a group, and a plurality of groups of second thread tooth type stripe width sequences of the second internal thread image which correspond to a second preset shooting angle and take a plurality of stripes as a group.

Fig. 5 shows a flow of implementing step 104 in the binocular vision-based internal thread geometric parameter measurement method provided by the embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and the detailed description is as follows:

in an embodiment of the present invention, in order to further improve the accuracy of measuring the geometric parameter of the internal thread, as shown in fig. 5, step 104 determines the actual thread form parameter of the internal thread according to the thread form streak width and the pitch length of the internal thread, including:

step 501, determining the pitch length of the internal thread by utilizing a preset calibrated corresponding relation of the thread pitch according to the thread density of the binarization bright and dark stripes of the first internal thread image and the thread density of the binarization bright and dark stripes of the second internal thread image;

step 502, determining actual parameters of the thread form of the internal thread according to the thread form image parameters of the internal thread, the thread pitch length and the sum of the thread form image parameters corresponding to the thread pitch length; the sum of the image parameters of the tooth profile corresponding to the pitch length is the sum of the image parameters of the tooth top, the left tooth side, the right tooth side and the tooth bottom of the tooth profile corresponding to the pitch length.

After determining the thread profile image parameters of the internal thread, the number of complete threads taken in the picture is inversely proportional to the pitch (length) in view of the fact that the imaging of the (optical) endoscopic probe (partial image of the internal thread) is a planar projection image. For example, if 5 sets of threads can be captured with a pitch of 2.5 mm, 8 sets of threads can be captured for a pitch of 1.5 mm. From this, a classification decision can be made on the pitch type based on the thread density to determine the pitch length. Namely, according to the thread density of the binaryzation bright and dark stripes of the internal thread image, the length of the thread pitch of the internal thread is determined by utilizing the corresponding relation of the thread pitch calibrated in advance. Wherein, the corresponding relation of the thread pitch reflects the corresponding relation between the thread density of the internal thread and the length of the thread pitch of the internal thread.

After the pitch length is determined, the actual parameter of the thread form of the internal thread can be determined based on the image parameter of the thread form of the internal thread, the pitch length and the image parameter sum of the thread form corresponding to the pitch length. Specifically, the actual tooth profile parameters of the internal thread can be determined by the following formula:

wherein L, t, r, d and h respectively represent the actual left flank width, the actual crest width, the actual right flank width, the actual root width and the actual thread height of the internal thread, ll, lt, lr and Ld respectively represent the left flank image parameter, the crest image parameter, the right flank image parameter and the root image parameter of the internal thread, and L represents the pitch length.

For example, if it is determined that the left tooth image parameter of the internal thread, the crest image parameter of the internal thread, the right tooth side image parameter of the internal thread and the root image parameter of the internal thread are 66, 50, 65 and 20 respectively, the thread length is 2.5 mm, and the image parameter sum of the tooth form corresponding to the pitch length is 66+, 50+, 65+20=201, then it may be determined that the actual width of the left tooth side of the internal thread is 66+, 50+, 65+, 20 =201based on the above formula

And (4) millimeter. The actual width of the crest of the internal thread, the actual width of the right flank of the internal thread and the actual width of the root of the internal thread can be calculated based on the above formula. Therefore, the precise measurement of the geometric parameters of the internal thread is realized.

In addition, according to the trapezoidal geometry, the difference dH between the pitch diameter and the minor diameter of the internal thread can be calculated by the following formula:

wherein h represents the actual tooth height of the internal thread, D2 and D1 respectively represent the pitch diameter and the minor diameter of the internal thread, and dH represents the difference between the pitch diameter and the minor diameter of the internal thread; l, t, r and d represent the actual widths of the left flank, crest, right flank and root of the internal thread, respectively.

In the embodiment of the invention, the thread pitch length of the internal thread is determined by utilizing the preset calibrated thread pitch corresponding relation according to the thread density of the binarization bright and dark stripes of the first internal thread image and the thread density of the binarization bright and dark stripes of the second internal thread image, and the actual thread form parameter of the internal thread is determined according to the thread form image parameter of the internal thread, the thread pitch length and the image parameter sum of the thread form corresponding to the thread pitch length, so that the measurement precision of the geometric parameter of the internal thread can be further improved.

It should be noted that, relative ratios of lengths of the portions of the dental model can be directly obtained based on the first preset shooting angle being 0 °, and then shooting can be performed at a second preset shooting angle (not 0 °); or based on the fact that the second preset shooting angle is 0 degrees, relative ratio values of lengths of all parts of the tooth form are directly obtained, shooting is conducted at the first preset shooting angle (not 0 degrees), and therefore measurement of the geometric parameters of the internal thread is achieved respectively. In addition, the shot first group of internal thread local images or second group of internal thread local images can be directly calculated to obtain the thread type parameters of the internal threads without image splicing, and then the thread type parameters of each thread of the whole threaded hole are obtained by sequencing.

The embodiment of the invention also provides a binocular vision-based internal thread tooth form geometric parameter measuring device, which is described in the following embodiment. Because the principle of solving the problems of the devices is similar to the method for measuring the geometric parameters of the internal thread tooth form based on binocular vision, the implementation of the devices can be referred to the implementation of the method, and repeated details are omitted.

Fig. 6 shows functional modules of the binocular vision-based internal thread geometric parameter measuring device provided by the embodiment of the invention, and for convenience of explanation, only the parts related to the embodiment of the invention are shown, and the details are as follows:

referring to fig. 6, each module included in the binocular vision-based internal thread geometric parameter measurement apparatus is used to execute each step in the embodiment corresponding to fig. 1, and specific reference is made to fig. 1 and the related description in the embodiment corresponding to fig. 1, which are not repeated herein. In the embodiment of the invention, the binocular vision-based internal thread tooth form geometric parameter measuring device comprises a local image shooting module 601, a stripe width determining module 602, an image parameter determining module 603 and a tooth form parameter determining module 604.

The local image shooting module 601 is configured to take a first group of local images of the internal threads at a first preset shooting angle in a stepping manner and take a second group of local images of the internal threads at a second preset shooting angle in a stepping manner by using the endoscope probe according to the stepping length.

A stripe width determining module 602, configured to determine a binary bright-dark stripe width of the bright-dark stripe width first internal thread image and a binary bright-dark stripe width of the bright-dark stripe width second internal thread image, respectively; the first internal thread image is formed by splicing a first group of internal thread local images, and the second internal thread image is formed by splicing a second group of internal thread local images.

The image parameter determining module 603 is configured to determine the tooth shape image parameters of the internal thread according to the binarized bright and dark stripe width of the first internal thread image and the binarized bright and dark stripe width of the second internal thread image by using a projection relationship between the tooth shape stripe width of the internal thread and the tooth shape image parameters of the internal thread at a shooting angle.

And a thread form parameter determining module 604 for determining a thread form actual parameter of the internal thread according to the thread form image parameter and the thread pitch length of the internal thread.

In the embodiment of the present invention, the local image capturing module 601 uses the endoscope probe to capture a first set of local images of the internal thread at a first preset capturing angle and a second set of local images of the internal thread at a second preset capturing angle respectively in a stepping manner according to the stepping length; the stripe width determining module 602 determines the binarization bright-dark stripe width of the first internal thread image of the bright-dark stripe width and the binarization bright-dark stripe width of the second internal thread image of the bright-dark stripe width respectively; the image parameter determining module 603 determines the thread pattern image parameters of the internal thread according to the binaryzation bright and dark stripe width of the bright and dark stripe width first internal thread image and the binaryzation bright and dark stripe width of the bright and dark stripe width second internal thread image by using the projection relation between the thread pattern stripe width of the internal thread and the thread pattern image parameters of the internal thread at a shooting angle; the thread form parameter determining module 604 determines the actual thread form parameter of the internal thread according to the thread form image parameter and the thread pitch length of the internal thread. According to the embodiment of the invention, the local image shooting module 601 shoots an internal thread image by using an endoscope probe, so that the measurement of the small-size deep hole of the internal thread is realized; and the statistical averaging is carried out along the trend of the internal thread, the credible tooth form parameters can still be obtained for the thread defects, and the measurement precision of the internal thread tooth form parameters is improved.

In a preferred embodiment, in order to improve the accuracy of capturing the internal thread image and further improve the accuracy of measuring the geometric parameters of the internal thread, the step length is set according to the number of threads contained in the captured local internal thread image.

In a preferred embodiment, in order to further improve the measurement accuracy of the geometric parameter of the internal thread, the first preset shooting angle and the second preset shooting angle are the same and opposite in direction.

In a preferred embodiment, in order to improve the accuracy of the internal thread image stitching and further improve the accuracy of the internal thread geometric parameter measurement, the overlapping portion of two adjacent frames of internal thread local images in the first set of internal thread local images is smaller than the thread pitch of the internal thread, and the overlapping portion of two adjacent frames of internal thread local images in the second set of internal thread local images is smaller than the thread pitch of the internal thread.

In a preferred embodiment, in order to further improve the accuracy of the measurement of the geometrical parameters of the internal thread, the sum of the flank angle of the internal thread and the absolute value of the first predetermined shooting angle is not greater than 90 °, and the sum of the flank angle of the internal thread and the absolute value of the second predetermined shooting angle is not greater than 90 °.

In a preferred embodiment, in order to facilitate the switching of the view angle of the endoscope probe and further improve the measurement accuracy of the geometric parameters of the internal thread, the variable angle plane reflecting mirror of the endoscope probe comprises two limiting angles, and the view angle of the variable angle plane reflecting mirror of the endoscope probe is switched through the link mechanism.

Fig. 7 shows a schematic structure of a local image capturing module 601 in the binocular vision-based internal thread geometric parameter measuring apparatus according to the embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, which are described in detail as follows:

in one embodiment of the invention, the head of the endoscopic probe is fitted with a variable angle plane mirror. In order to improve the accuracy of capturing the local image of the internal thread and further improve the measurement accuracy of the geometric parameters of the internal thread, referring to fig. 7, each unit included in the local image capturing module 601 is configured to execute each step in the embodiment corresponding to fig. 2, and specifically, refer to fig. 2 and the related description in the embodiment corresponding to fig. 2, which are not repeated herein. In the embodiment of the present invention, the partial image capturing module 601 includes a first partial image capturing unit 701 and a second partial image capturing unit 702.

A first partial image capturing unit 701 for capturing a first set of partial images of the internal thread step by step from a start position to an end position of the internal thread at a first preset capturing angle by a step length using an endoscopic probe having a variable angle plane mirror mounted on a head; the first preset shooting angle is an acute angle included angle formed by the intersection of a reflection light plane on a variable-angle plane reflector of the endoscope probe and a vertical central axis plane of the internal thread along a first incident light plane from the initial position to the final position of the horizontal central axis plane of the internal thread, and the included angle formed by the first incident light plane and a normal plane of the variable-angle plane reflector is an acute angle.

A second local image shooting unit 702, configured to take a second set of local images of the internal thread in a step-by-step manner from the ending position to the starting position of the internal thread at a second preset shooting angle according to the step length by using the endoscope probe with the variable-angle plane mirror mounted on the head; the second preset shooting angle is an acute angle included angle formed by the intersection of a reflection light plane on the variable-angle plane reflector of the endoscope probe and the vertical central axis plane of the internal thread along a second incident light plane from the termination position to the starting position of the horizontal central axis plane of the internal thread, and the included angle formed by the second incident light plane and the normal plane of the variable-angle plane reflector is an acute angle.

In the embodiment of the present invention, the first partial-image capturing unit 701 takes a first set of partial images of the internal thread step by step from the start position to the end position of the internal thread at a first preset capturing angle α 1 by a step length using an endoscope probe having a variable-angle plane mirror mounted on the head; the first preset shooting angle alpha 1 is an acute angle included angle formed by the intersection of a reflecting light plane of a first incident light plane from the initial position to the final position of the horizontal middle axial plane of the internal thread on a variable-angle plane reflector of an endoscope probe and the vertical middle axial plane of the internal thread; the second local image capturing unit 702 captures a second set of local images of the internal thread in a stepping manner from the end position to the start position of the internal thread by a second preset capturing angle α 2 according to the stepping length by using the endoscope probe with the variable-angle plane mirror mounted on the head, where the second preset capturing angle α 2 is an acute angle included angle formed by the intersection of the reflected light plane of a second incident light plane from the end position to the start position of the horizontal middle axis plane of the internal thread on the variable-angle plane mirror of the endoscope probe and the vertical middle axis plane of the internal thread. In the embodiment of the invention, the first preset shooting angle alpha 1 and the second preset shooting angle alpha 2 are symmetrical, so that the shooting accuracy of the local image of the internal thread can be improved, and the measurement accuracy of the geometric parameters of the internal thread is further improved.

Fig. 8 shows a structural schematic diagram of a stripe width determining module 602 in the binocular vision-based internal thread tooth geometry parameter measuring device provided by the embodiment of the invention, and for convenience of explanation, only the parts related to the embodiment of the invention are shown, and the details are as follows:

in an embodiment of the present invention, in order to improve the accuracy of determining the stripe width and further improve the precision of the geometric parameters of the internal thread, referring to fig. 8, each unit included in the stripe width determining module 602 is configured to execute each step in the embodiment corresponding to fig. 3, specifically refer to fig. 3 and the related description in the embodiment corresponding to fig. 3, and are not repeated herein. In the embodiment of the present invention, the stripe width determining module 602 includes a splicing unit 801, a stripe extracting unit 802, a denoising unit 803, and a stripe width determining unit 804.

The splicing unit 801 is configured to splice the first group of local images of the internal threads to form a first internal thread image, and splice the second group of local images of the internal threads to form a second internal thread image.

A stripe extracting unit 802, configured to extract a binarized bright-dark stripe of the first internal thread image and a binarized bright-dark stripe of the second internal thread image by using adaptive thresholds, respectively.

The noise reduction unit 803 is configured to perform noise reduction on the extracted binarization bright and dark stripes of the first internal thread image and the extracted binarization bright and dark stripes of the second internal thread image through mean value blurring and closing operations, so as to obtain the binarization bright and dark stripes of the first internal thread image and the binarization bright and dark stripes of the second internal thread image after noise reduction;

the stripe width determining unit 804 is configured to segment and mark the denoised binarized bright and dark stripe of the first internal thread image and the binarized bright and dark stripe of the second internal thread image by using morphological image processing, and determine a binarized bright and dark stripe width of the first internal thread image and a binarized bright and dark stripe width of the second internal thread image.

In the embodiment of the present invention, a splicing unit 801 splices a first group of internal thread local images to form a first internal thread image and splices a second group of internal thread local images to form a second internal thread image, a strip extraction unit 802 extracts binary light and dark strips of the first internal thread image and binary light and dark strips of the second internal thread image by using adaptive thresholds, a noise reduction unit 803 reduces noise of the extracted binary light and dark strips of the first internal thread image and the extracted binary light and dark strips of the second internal thread image by using mean value blurring and closing operations, so as to obtain the noise-reduced binary light and dark strips of the first internal thread image and the noise-reduced binary light and dark strips of the second internal thread image, and a strip width determination unit 804 cuts and marks the noise-reduced binary light and dark strips of the first internal thread image and the noise-reduced binary light and dark strips of the second internal thread image by using morphological image processing, so as to determine widths of the binary light and dark strips of the first internal thread image and the binary light and dark strips of the second internal thread image. In the embodiment of the present invention, the stripe extraction unit 802 extracts the binary bright and dark stripes of the internal thread image by using the adaptive threshold, the noise reduction unit 803 reduces the noise of the binary bright and dark stripes of the internal thread image by mean value blurring and closing operation, and finally the stripe width determination unit 804 determines the binary bright and dark stripe width of the internal thread image by using morphological image processing, so that the accuracy of determining the stripe width can be improved, and the precision of the internal thread geometric parameters can be further improved.

Fig. 9 shows a structural schematic diagram of the image pixel determining module 603 in the binocular vision-based internal thread geometric parameter measuring apparatus according to the embodiment of the present invention, and for convenience of illustration, only the parts related to the embodiment of the present invention are shown, and detailed below:

in an embodiment of the present invention, in order to improve the accuracy of determining the width of the internal thread profile stripe and further improve the measurement accuracy of the internal thread geometric parameter, referring to fig. 9, each unit included in the image parameter determining module 603 is configured to perform each step in the embodiment corresponding to fig. 4, specifically please refer to fig. 4 and the related description in the embodiment corresponding to fig. 4, which is not repeated herein. In this embodiment of the present invention, the image parameter determining module 603 includes a stripe aligning unit 901 and an image parameter determining unit 902.

The streak alignment unit 901 is configured to align the binarized light and dark streaks of the first internal thread image and the binarized light and dark streaks of the second internal thread image at the start position or the end position of the internal thread to obtain a plurality of sets of first thread form streak width sequences of the first internal thread image corresponding to the first preset shooting angle and taking the plurality of streaks as a set, and a plurality of sets of second thread form streak width sequences of the second internal thread image corresponding to the second preset shooting angle and taking the plurality of streaks as a set.

An image parameter determining unit 902, configured to determine a first thread image parameter and a second thread image parameter of the internal thread according to the multiple sets of first thread stripe width sequences and the multiple sets of second thread stripe width sequences and by using a projection relationship between the thread stripe width of the internal thread and the thread image parameter of the internal thread at a shooting angle.

In the embodiment of the present invention, the stripe aligning unit 901 aligns the binarized bright and dark stripes of the first internal thread image and the binarized bright and dark stripes of the second internal thread image at the start position or the end position of the internal thread to obtain a plurality of sets of first thread profile stripe width sequences of the first internal thread image corresponding to the first preset shooting angle and taking a plurality of sets of second thread profile stripe width sequences of the second internal thread image corresponding to the second preset shooting angle and taking a plurality of stripes as a set, and the image parameter determining unit 902 determines the first profile image parameters and the second profile image parameters of the internal thread according to the plurality of sets of first thread profile stripe width sequences and the plurality of sets of second thread profile stripe width sequences and by using the projection relationship between the profile stripe width of the internal thread and the profile image parameters of the internal thread at the shooting angle, so as to improve the accuracy of determining the internal thread profile image parameters and further improve the measurement accuracy of the internal thread geometric parameters.

Fig. 10 shows a schematic configuration of the thread form parameter determining module 604 of the binocular vision-based internal thread form geometric parameter measuring apparatus provided by the embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and the detailed description is as follows:

in an embodiment of the present invention, in order to further improve the measurement accuracy of the internal thread geometric parameter, referring to fig. 10, each unit included in the tooth profile parameter determining module 604 is used to execute each step in the embodiment corresponding to fig. 5, and specific reference is made to fig. 5 and the related description in the embodiment corresponding to fig. 5, which are not repeated herein. In the embodiment of the present invention, the dental pattern parameter determining module 604 includes a pitch length determining unit 1001 and a dental pattern parameter determining unit 1002.

A pitch length determining unit 1001 configured to determine the pitch length of the internal thread by using a preset calibrated corresponding relationship of the thread pitch according to the thread density of the binarized bright and dark stripes of the first internal thread image and the thread density of the binarized bright and dark stripes of the second internal thread image.

The thread form parameter determining unit 1002 is configured to determine a thread form actual parameter of the internal thread according to the thread form image parameter of the internal thread, the thread pitch length, and a thread form image parameter sum corresponding to the thread pitch length; the sum of the image parameters of the tooth profile corresponding to the pitch length is the sum of the image parameters of the tooth top, the left tooth side, the right tooth side and the tooth bottom of the tooth profile corresponding to the pitch length.

In the embodiment of the present invention, the pitch length determining unit 1001 determines the pitch length of the internal thread according to the thread density of the binarized bright and dark stripes of the first internal thread image and the thread density of the binarized bright and dark stripes of the second internal thread image by using the thread pitch correspondence relationship calibrated in advance, and the thread profile parameter determining unit 1002 determines the actual thread profile parameter of the internal thread according to the thread profile image parameter of the internal thread, the thread pitch length, and the image parameter sum of the thread profile corresponding to the thread pitch length, so as to further improve the measurement accuracy of the geometric parameter of the internal thread.

The embodiment of the invention has the following beneficial technical effects:

(1) The endoscope probe is used for shooting the internal thread, the small threaded hole can be visually measured only by manufacturing the small-diameter endoscope probe, and the laser line is used for shooting at variable angles outside the threaded hole after being projected outside the threaded hole, so that the detection of the small threaded hole cannot be realized;

(2) The picture shot by the invention is a two-dimensional projection of the screw thread, and because the transverse statistical averaging can be carried out along the trend of the screw thread, credible screw thread form parameters can still be obtained for the defect positions such as thread jump angles, cracks and the like; meanwhile, the width of each part of the screw thread can be corrected by using texture characteristics, and the method still has universality on the conditions of chamfer angles, non-trapezoidal screw threads and the like. In addition, the two-dimensional image can be used for detecting the defects of the thread surface, and if rotation control is added in the shooting process, all the appearance information of the whole internal thread surface can be obtained.

In summary, in the embodiment of the present invention, the endoscope probe is used to take the first group of local images of the internal thread at the first preset taking angle step by step and to take the second group of local images of the internal thread at the second preset taking angle step by step according to the step length; respectively determining the binaryzation bright-dark stripe width of the first internal thread image with the bright-dark stripe width and the binaryzation bright-dark stripe width of the second internal thread image with the bright-dark stripe width; determining the tooth shape image parameters of the internal thread by utilizing the projection relation between the tooth shape stripe width of the internal thread and the tooth shape image parameters of the internal thread under a shooting angle according to the binaryzation light and dark stripe width of the first internal thread image with the light and dark stripe width and the binaryzation light and dark stripe width of the second internal thread image with the light and dark stripe width; and determining the actual tooth form parameters of the internal thread according to the tooth form image parameters and the pitch length of the internal thread. According to the embodiment of the invention, the endoscope probe is used for shooting the image of the internal thread, so that the measurement of the small-size deep hole of the internal thread is realized; and the statistical averaging is carried out along the trend of the internal thread, the credible tooth form parameters can still be obtained for the thread defects, and the measurement precision of the internal thread tooth form parameters is improved.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present invention has been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

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 scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A binocular vision-based internal thread tooth form geometric parameter measuring method is characterized by comprising the following steps:

and determining actual parameters of the thread form of the internal thread according to the thread form image parameters and the thread pitch length of the internal thread.

2. The binocular vision-based internal thread profile geometric parameter measuring method of claim 1, wherein the variable angle plane mirror is installed at a head of the endoscope probe, and the step-shooting of the first set of internal thread partial images and the step-shooting of the second set of internal thread partial images at the first preset shooting angle and the step-shooting of the second preset shooting angle, respectively, using the endoscope probe according to the step length comprises:

an endoscope probe with a variable-angle plane reflector mounted at the head part is used for shooting a first group of local images of the internal thread in a stepping mode from the initial position to the final position of the internal thread at a first preset shooting angle according to the stepping length; the first preset shooting angle is an acute angle included angle formed by the intersection of a reflection light plane on a variable angle plane reflector of the endoscope probe and a vertical middle axial plane of the internal thread along a first incident light plane from the initial position to the final position of the horizontal middle axial plane of the internal thread, and the included angle formed by the first incident light plane and a normal plane of the variable angle plane reflector is an acute angle;

an endoscope probe with a variable-angle plane reflector mounted at the head is used for shooting a second group of local images of the internal threads in a stepping mode from the end position to the initial position of the internal threads at a second preset shooting angle according to the stepping length; the second preset shooting angle is an acute angle included angle formed by the intersection of a reflection light plane of a second incident light plane from the termination position to the starting position of the horizontal middle axial plane of the internal thread on a variable angle plane reflector of the endoscope probe and the vertical middle axial plane of the internal thread; the included angle between the second incident light plane and the normal plane of the variable angle plane reflector is an acute angle.

3. The binocular vision-based internal thread form geometric parameter measuring method of claim 2, wherein the step length is set according to the number of threads included in the photographed internal thread partial image; and/or

The first preset shooting angle is the same as the second preset shooting angle, and the direction of the first preset shooting angle is opposite to that of the second preset shooting angle; and/or

Overlapping parts of two adjacent frames of internal thread local images in the first group of internal thread local images are smaller than the thread pitch of the internal thread, and overlapping parts of two adjacent frames of internal thread local images in the second group of internal thread local images are smaller than the thread pitch of the internal thread; and/or

The sum of the flank angle of the internal thread and the absolute value of the first preset shooting angle is not more than 90 degrees, and the sum of the flank angle of the internal thread and the absolute value of the second preset shooting angle is not more than 90 degrees.

4. The binocular vision-based internal thread dental geometry parameter measuring method of claim 1, wherein the variable angle plane mirror of the endoscope probe includes two limit angles, and the angle of view of the variable angle plane mirror of the endoscope probe is switched by a link mechanism.

5. The binocular vision based internal thread tooth form geometric parameter measuring method as recited in claim 1, wherein a binarized bright and dark stripe width of a first internal thread image and a binarized bright and dark stripe width of a second internal thread image of bright and dark stripe widths are respectively determined; the first internal thread image is formed by splicing a first group of internal thread local images, and the second internal thread image is formed by splicing a second group of internal thread local images, and the method comprises the following steps:

respectively splicing the first group of internal thread local images to form a first internal thread image, and splicing the second group of internal thread local images to form a second internal thread image;

respectively extracting the binarization bright and dark stripes of the first internal thread image and the binarization bright and dark stripes of the second internal thread image by using a self-adaptive threshold value;

denoising the extracted binarization bright and dark stripes of the first internal thread image and the extracted binarization bright and dark stripes of the second internal thread image through mean value fuzzy and closed operation respectively to obtain the binarization bright and dark stripes of the first internal thread image and the binarization bright and dark stripes of the second internal thread image after denoising;

and respectively utilizing morphological image processing to cut and mark the binarized bright and dark stripes of the first internal thread image and the binarized bright and dark stripes of the second internal thread image after noise reduction, and determining the binarized bright and dark stripe width of the first internal thread image and the binarized bright and dark stripe width of the second internal thread image.

6. The binocular vision-based internal thread profile geometric parameter measuring method as recited in claim 1, wherein the determining of the internal thread profile image parameter using the projection relationship between the internal thread profile strip width at a photographing angle and the internal thread profile image parameter according to the binarized bright-dark strip width of the bright-dark strip width first internal thread image and the binarized bright-dark strip width of the bright-dark strip width second internal thread image comprises:

aligning the binaryzation bright and dark stripes of the first internal thread image and the binaryzation bright and dark stripes of the second internal thread image at the starting position or the ending position of the internal thread to obtain a plurality of groups of first thread tooth type stripe width sequences of the first internal thread image which correspond to a first preset shooting angle and take a plurality of stripes as a group and a plurality of groups of second thread tooth type stripe width sequences of the second internal thread image which correspond to a second preset shooting angle and take a plurality of stripes as a group;

and determining the first thread pattern image parameters and the second thread pattern image parameters of the internal thread by utilizing the projection relation between the thread pattern stripe width of the internal thread and the thread pattern image parameters of the internal thread under the shooting angle according to the plurality of groups of first thread pattern stripe width sequences and the plurality of groups of second thread pattern stripe width sequences.

7. The binocular vision based internal thread profile geometric parameter measuring method as set forth in claim 1, wherein determining the actual profile parameters of the internal thread according to the profile image parameters and the pitch length of the internal thread comprises:

determining the pitch length of the internal thread by utilizing a preset calibrated corresponding relation of the thread pitch according to the thread density of the binarization bright and dark stripes of the first internal thread image and the thread density of the binarization bright and dark stripes of the second internal thread image;

determining actual parameters of the thread form of the internal thread according to the thread form image parameters of the internal thread, the thread pitch length and the thread form image parameter sum corresponding to the thread pitch length; the sum of the image parameters of the tooth profile corresponding to the pitch length is the sum of the image parameters of the tooth top, the left tooth side, the right tooth side and the tooth bottom of the tooth profile corresponding to the pitch length.

8. The utility model provides an internal thread tooth form geometric parameters measuring device based on binocular vision which characterized in that includes:

the image parameter determining module is used for determining the tooth form image parameters of the internal thread by utilizing the projection relation between the tooth form stripe width of the internal thread and the tooth form image parameters of the internal thread under a shooting angle according to the binaryzation bright and dark stripe width of the first internal thread image with the bright and dark stripe width and the binaryzation bright and dark stripe width of the second internal thread image with the bright and dark stripe width;

and the thread form parameter determining module is used for determining the actual thread form parameters of the internal thread according to the thread form image parameters and the thread pitch length of the internal thread.

9. A computer apparatus comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the binocular vision based internal thread geometry measuring method of any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, wherein the computer-readable storage medium stores a computer program for executing the binocular vision based internal thread geometry parameter measuring method of any one of claims 1 to 7.