CN115585736B

CN115585736B - Method and device for measuring geometric parameters of internal thread teeth based on binocular vision

Info

Publication number: CN115585736B
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: 2023-11-28
Anticipated expiration: 2041-06-22
Also published as: CN115585736A

Abstract

The invention discloses a binocular vision-based internal thread geometry parameter measurement method and device, wherein the method comprises the steps of utilizing an endoscope probe to shoot a first group of internal thread partial images in a stepping mode according to a stepping length at a first preset shooting angle, and shooting a second group of internal thread partial images in a stepping mode at a second preset shooting angle; determining the binarization bright-dark stripe width of the first internal thread image and the bright-dark stripe width of the second internal thread image; according to the binarization bright-dark stripe width of the first internal thread image and the second internal thread image, determining the profile image parameters of the internal thread by utilizing the corresponding relation between the profile stripe width and the profile image parameters under the shooting angle; and determining the actual parameters of the internal thread tooth form according to the internal thread tooth form image parameters and the thread pitch length. According to the invention, an endoscope probe is used for shooting an internal thread image, so that the measurement of a small-size deep hole of an internal thread is realized; and the statistical average is carried out along the trend of the internal thread, so that the measurement accuracy of the internal thread profile parameters is improved.

Description

Method and device for measuring geometric parameters of internal thread teeth 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 internal thread teeth 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 mainly relates to detection items comprising detection of internal thread surface appearance defects, form and position tolerances, geometric parameters and the like. At present, a contact type measuring method is widely used in the industrial field, and comprises 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 being shifted toward a nondestructive and rapid non-contact measurement method. Currently, methods such as industrial microscopes, eddy current detection, laser detection and machine vision exist for non-contact detection. Machine vision inspection techniques have been primarily used in the field of thread inspection. For external threads, usually, back lighting is used to take a picture on the side of the thread, and the geometrical parameters of the teeth are obtained through image processing; for internal threads, the best technology is to use laser-word line illumination, and a camera shoots a corrugated bright line on the thread from a specific angle, and calculate the geometric parameters of the internal thread profile based on the principle of triangulation.

Traditional contact measurement can only measure one section of the internal thread, but cannot obtain full-size measurement; in a large amount of industrial quality tests, the quality of threads can only be checked by adopting thread passing and non-stop regulations, and accurate quantitative detection can not be carried out on all threads, 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, illumination cannot penetrate into an inner hole, and internal thread tooth type detection is difficult to be carried out on a small-size deep hole.

Disclosure of Invention

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

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

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

According to the binarization light and dark stripe width of the first internal thread image and the binarization light and dark stripe width of the second internal thread image, determining the profile image parameters of the internal thread by utilizing the projection relation between the profile stripe width of the internal thread and the profile image parameters of the internal thread under the shooting angle;

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

The embodiment of the invention also provides an internal thread form geometric parameter measuring device based on binocular vision, which is used for measuring internal thread 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 way at a first preset shooting angle and shooting a second group of internal thread local images in a stepping way at a second preset shooting angle respectively by utilizing the endoscope probe according to the stepping length;

the stripe width determining module is used for determining the binarization light and dark stripe width of the first internal thread image and the binarization light and dark stripe width of the second internal thread image of the light and dark stripe width respectively; the first internal thread image is formed by splicing a first group of internal thread partial images, and the second internal thread image is formed by splicing a second group of internal thread partial images;

The image parameter determining module is used for determining the profile image parameters of the internal thread by utilizing the projection relationship between the profile width of the internal thread and the profile image parameters of the internal thread under the shooting angle according to the binarization light-dark stripe width of the first internal thread image with the light-dark stripe width and the binarization light-dark stripe width of the second internal thread image with the light-dark stripe width;

the tooth form parameter determining module is used for determining the actual tooth form parameters of the internal thread according to the tooth form image parameters and the screw 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 stored on the memory and capable of running on the processor, wherein the processor realizes the method for measuring the geometric parameters of the internal thread profile based on binocular vision when executing the computer program.

The embodiment of the invention also provides a computer readable storage medium which stores a computer program for executing the binocular vision-based internal thread form geometric parameter measuring method.

In the embodiment of the invention, an endoscope probe is utilized to step and shoot a first group of internal thread partial images at a first preset shooting angle and a second group of internal thread partial images at a second preset shooting angle according to the step length; respectively determining the binarization bright-dark stripe width of the first internal thread image with the bright-dark stripe width and the binarization bright-dark stripe width of the second internal thread image with the bright-dark stripe width; according to the binarization light and dark stripe width of the first internal thread image and the binarization light and dark stripe width of the second internal thread image, determining the profile image parameters of the internal thread by utilizing the projection relation between the profile stripe width of the internal thread and the profile image parameters of the internal thread under the shooting angle; and determining the actual parameters of the internal thread tooth form according to the internal thread tooth form image parameters and the thread pitch length. According to the embodiment of the invention, an endoscope probe is used for shooting an internal thread image, so that the measurement of a small-size deep hole of an internal thread is realized; and the reliable tooth form parameters can be obtained for the thread defects along the trend statistical average of the internal threads, so that the measurement accuracy of the internal thread tooth form parameters is improved.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. In the drawings:

fig. 1 is a flowchart of an implementation of a binocular vision-based internal thread form geometric parameter measurement method according to an embodiment of the present invention;

fig. 1-1 is a schematic view of shooting an internal thread according to an embodiment of the present invention;

fig. 1-2 are schematic views of partial images of internal threads at a certain viewing angle according to an embodiment of the present invention;

fig. 1-3 are schematic views of partial images of internal threads when a shooting angle provided by the embodiment of the invention is greater than 0 °;

fig. 1 to 4 are schematic views of partial images of internal threads when a shooting angle provided by the embodiment of the invention is smaller than 0 °;

FIGS. 1-5 are schematic diagrams illustrating a correspondence between a width of a profile stripe of an internal thread and profile image parameters of the internal thread according to an embodiment of the present invention;

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

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

fig. 4 is a flowchart illustrating an implementation of step 103 in the binocular vision-based internal thread form geometric parameter measurement method according to an embodiment of the present invention;

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

FIG. 6 is a functional block diagram of an internal thread form geometrical parameter measuring device 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 form geometric parameter measuring device according to an embodiment of the present invention;

fig. 8 is a block diagram of a stripe width determining module 602 in the binocular vision-based internal thread form geometric parameter measuring device according to an embodiment of the present invention;

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

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

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention will be described in further detail with reference to the accompanying drawings. The exemplary embodiments of the present invention and their descriptions herein are for the purpose of explaining the present invention, but are not to be construed as limiting the invention.

Fig. 1 shows a flow of implementation of the binocular vision-based internal thread form geometric parameter measurement method according to the embodiment of the present invention, and for convenience of description, only the portions relevant to the embodiment of the present invention are shown, and the details are as follows:

as shown in fig. 1, the method for measuring the geometric parameters of the internal thread profile based on binocular vision comprises the following steps:

step 101, respectively shooting a first group of internal thread partial images in a stepping way at a first preset shooting angle and shooting a second group of internal thread partial images in a stepping way at a second preset shooting angle by utilizing an endoscope probe according to the stepping length;

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

Step 103, determining the profile image parameters of the internal thread by utilizing the projection relationship between the profile stripe width of the internal thread and the profile image parameters of the internal thread under the shooting angle according to the binarization light-dark stripe width of the first internal thread image with the light-dark stripe width and the binarization light-dark stripe width of the second internal thread image with the light-dark stripe width;

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

When the geometrical parameters of the internal thread are measured, the internal thread can be shot by using an endoscope probe. Generally, the internal thread hole is relatively small, the geometric parameter measurement of the small-aperture internal thread can be realized only by manufacturing an endoscope probe with a small diameter for the small thread hole, and the laser word line is subjected to angle-variable shooting outside the thread hole after the external projection of the thread hole, so that the geometric parameter measurement of the small-aperture internal thread cannot be realized. Fig. 1-1 shows an internal thread photographing schematic provided by an embodiment of the present invention, when an endoscope probe is used to photograph an internal thread, a first group of internal thread partial images is photographed in a stepping manner according to a stepping length at a first preset photographing angle α1, and then a second group of internal thread partial images is photographed in a stepping manner according to a stepping length at a second preset photographing angle α2. Fig. 1-2 show a schematic view of a partial internal thread image at a certain viewing angle according to an embodiment of the present invention, and as can be seen from fig. 1-2, the crest and the root are near perpendicular to the incident light direction, the reflected light intensity is high, the reflected light intensity at the tooth side is low, and the partial internal thread image actually shows streaks with alternate brightness. The bending direction of the bright and dark fringes is shown in fig. 1-3 and fig. 1-4 according to the difference of the magnitude relation between the shooting angle and 0 degrees. Fig. 1 to 3 show a partial image illustration of the internal thread when the photographing angle is greater than 0 deg., and fig. 1 to 4 show a partial image illustration of the internal thread when the photographing angle is less than 0 deg..

In a preferred embodiment, in order to improve accuracy of capturing the internal thread image, further accuracy of measuring the internal thread geometric parameter is set according to the number of threads included in the captured internal thread partial image. The step-size progress M is set on the principle that the number of threads included in the shot internal thread partial image is N/M, and the step-size progress M and the number of threads included in the internal thread partial image are integers as much as possible. The specific step size progress value may be specifically set according to the number of threads and the number of threads included in the captured partial internal thread 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 internal thread geometric parameter, the first preset photographing angle α1 and the second preset photographing angle α2 are the same in angle and opposite in direction. When the first preset shooting angle α1 and the second preset shooting angle α2 are set, the first preset shooting angle α1 and the second preset shooting angle α2 are preferably symmetrical, that is, the first preset shooting angle α1 and the second preset shooting angle α2 are the same in angle and opposite in direction. The first preset shooting angle alpha 1 is symmetrical with the second preset shooting angle alpha 2, so that the accuracy of measuring the geometric parameters of the internal threads can be improved as much as possible on the premise of avoiding angle shielding, and the influence of angle errors is reduced.

In a preferred embodiment, in order to improve accuracy of the stitching of the internal thread images, accuracy of the measurement of the geometric parameters of the internal thread is further improved, an overlapping portion of two adjacent frames of internal thread partial images in the first set of internal thread partial images is smaller than a pitch of the internal thread, and an overlapping portion of two adjacent frames of internal thread partial images in the second set of internal thread partial images is smaller than the pitch of the internal thread. The overlapping part of two adjacent frames of internal thread partial images in the internal thread partial images is smaller than the pitch of the internal thread, so that the internal thread partial images can be spliced conveniently, the accuracy of the internal thread image splicing is improved, and the accuracy of internal thread geometric parameter measurement 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 photographing angle α1 is not more than 90 °, and the sum of the flank angle of the internal thread and the absolute value of the second preset photographing angle α2 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, so that the situation that the view angle of the endoscope probe deviates from the lateral direction of the thread to be too large, and two dental sides are shielded during imaging is avoided, and the sum of the dental side angle and the shooting angle is required to be not more than 90 degrees. For example, the first preset shooting angle α1 and the second preset shooting angle α2 can be respectively selected from 20 ° and-20 ° for the internal thread of 60 ° flank angle.

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 mirror of the endoscope probe comprises two limiting angles, and the view angle of the variable angle plane mirror of the endoscope probe is switched through the link mechanism. The variable angle range of the variable angle plane mirror of the endoscope probe is limited through the two limiting angles, and meanwhile, the visual angle of the variable angle plane mirror of the endoscope probe is conveniently switched by using the link mechanism, so that the measurement accuracy of the geometric parameters of the internal threads is further improved.

After the endoscope probe is used for respectively shooting a first group of internal thread partial images and a second group of internal thread partial images, the first group of internal thread partial images are spliced to form a first internal thread image, and the second group of internal thread partial images are spliced to form a second internal thread image, so that the binarization bright-dark stripe width of the first internal thread image and the binarization bright-dark stripe width of the second internal thread image with the bright-dark stripe width are respectively determined through image processing.

After the binarization bright-dark stripe width of the first internal thread image and the binarization bright-dark stripe width of the second internal thread image with the bright-dark stripe width are respectively obtained, the projection relation between the thread image parameters of the internal thread and the stripe width under the shooting angle is utilized to determine the thread image parameters of the internal thread. Fig. 1 to 5 show schematic correspondence between the width of the profile stripe of the internal thread and the profile image parameters of the internal thread according to the embodiment of the present invention. As can be seen from fig. 1 to 5, a specific projection relationship exists between the stripe width of the internal thread, the photographing angle and the profile image parameters of the internal thread. Thus, the projection relationships shown in FIGS. 1-5 may be utilized to determine the profile image parameters of the internal thread based on the binarized bright-dark stripe width. The dental image parameters defined by the binarization bright-dark stripe width of the binarization bright-dark stripe width first internal thread image and the binarization bright-dark stripe width of the bright-dark stripe width second internal thread image comprise Ll, lt, lr, ld, lh, which respectively represent the 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 dental stripe after projection conversion.

The relationship between the imaging angle and the profile 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 left flank stripe width, crest stripe width, right flank stripe width and root stripe width of the internal thread; ll, lt, lr and Ld respectively represent a left-side image parameter, a crest image parameter, a right-side image parameter and a root image parameter of the internal thread, and Lh represents a tooth height image parameter of the internal thread; alpha is the shooting angle.

The dental image parameters and dental actual parameters are simple proportional relations, the proportional coefficient a represents the actual length of a millimeter corresponding to a pixel in a photo, and the proportional coefficient a can be calculated by using the pitch, because the pitch length L corresponds to the sum of the dental image parameters of the root, the left side, the dental top and the right side of a dental form: l=a× (ld+ll+lt+lr)

Accordingly, in determining the dental form image parameter of the internal thread, a scaling factor between the dental form image parameter and the dental form actual parameter is determined based on the sum of the pitch length L and the dental root, left side, crest and right side image parameters of the dental form, and the dental form actual parameter of the internal thread is determined based on the dental form image parameter and the scaling factor.

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

According to the embodiment of the invention, an endoscope probe is used for shooting an internal thread image, so that the measurement of a small-size deep hole of an internal thread is realized; and the reliable tooth form parameters can be obtained for the thread defects along the trend statistical average of the internal threads, so that the measurement accuracy of the internal thread tooth form parameters is improved.

Fig. 2 shows a flow of implementation of step 101 in the binocular vision-based internal thread form geometric parameter measurement method according to the embodiment of the present invention, and for convenience of description, only the relevant parts of the embodiment of the present invention are shown, which is described in detail below:

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

step 201, utilizing an endoscope probe with a head provided with a variable angle plane reflecting mirror to step and shoot a first group of internal thread partial images from the initial position to the final position of the internal thread according to the step length at a first preset shooting angle; the first preset shooting angle is an acute angle formed by intersecting a reflection light plane on a variable angle plane reflecting mirror of the endoscope probe and a vertical middle axis surface of the internal thread along the initial position of the horizontal middle axis surface of the internal thread and the first incident light plane at the final position, and the angle formed by the first incident light plane and the normal plane of the variable angle plane reflecting mirror is an acute angle;

step 202, utilizing an endoscope probe with a head provided with a variable angle plane mirror to step and shoot a second group of internal thread partial images from the ending position to the starting position of the internal thread at a second preset shooting angle according to the step length; the second preset shooting angle is an acute included angle formed by intersecting a reflected light plane on a variable angle plane reflector of the endoscope probe and a vertical middle axis surface of the internal thread along a second incident light plane from a final position to a starting position of the horizontal middle axis surface 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 mirror, and the shooting angle (visual angle) of the variable angle plane mirror of the endoscope probe can be adjusted by changing the angle of the plane mirror. Referring to fig. 1-2, when the endoscope probe is used to shoot the first group of internal thread partial images and the second group of internal thread partial images respectively, the angle of the endoscope probe head variable angle plane mirror is adjusted first, and the first group of internal thread partial images are shot in steps from the initial position to the final position of the internal thread at a first preset shooting angle alpha 1 according to a set step length. The first preset shooting angle alpha 1 is an acute included angle formed by intersecting a reflection light plane on a variable angle plane reflecting mirror of the endoscope probe and a vertical middle axis surface of the internal thread, wherein the first incidence light plane is located at a starting position and a final position along the horizontal middle axis surface 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 endoscope probe head variable angle plane mirror is adjusted, and the second preset shooting angle alpha 2 is used for shooting from the ending position of the internal thread to the starting position in a stepping way according to the set stepping length, so that a second group of internal thread partial images are obtained. The second preset shooting angle alpha 2 is an acute included angle formed by intersecting a reflected light plane on the variable angle plane mirror of the endoscope probe and a vertical middle axis surface of the internal thread along a second incident light plane from a termination position to a start position of the horizontal middle axis surface of the internal thread. I.e. the first preset photographing angle α1 is symmetrical to the second preset photographing angle α2. 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 head provided with a variable angle plane reflecting mirror is used for shooting a first group of internal thread partial images step by step from the initial position to the final position of the internal thread at a first preset shooting angle alpha 1 according to the step length; the first preset shooting angle alpha 1 is an acute included angle formed by intersecting a reflected light plane on a variable angle plane reflector of the endoscope probe and a vertical middle axis surface of the internal thread along a first incident light plane of a starting position and a final position of the horizontal middle axis surface of the internal thread; and the endoscope probe with the head provided with the variable angle plane mirror is used for shooting a second group of internal thread partial images step by step from the ending position to the starting position of the internal thread by a second preset shooting angle alpha 2 according to the step length, wherein the second preset shooting angle alpha 2 is an acute angle formed by intersecting a reflected light plane on the variable angle plane mirror of the endoscope probe and a vertical middle axis plane of the internal thread along the ending position to the starting position of the horizontal 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 partial image of the internal thread can be improved, and the measurement accuracy of the geometric parameter of the internal thread can be further improved.

Fig. 3 shows a flow of implementation of step 102 in the binocular vision-based internal thread form geometric parameter measurement method according to the embodiment of the present invention, and for convenience of description, only the relevant parts of the embodiment of the present invention are shown, which is described in detail below:

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

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

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

step 303, noise reduction is carried out on the extracted binarization bright-dark stripes of the first internal thread image and the extracted binarization bright-dark stripes of the second internal thread image through mean value blurring and closing operation respectively, and the binarization bright-dark stripes of the first internal thread image and the binarization bright-dark stripes of the second internal thread image after noise reduction are obtained;

Step 304, dividing and marking the binarized bright-dark stripe of the first internal thread image and the binarized bright-dark stripe of the second internal thread image after noise reduction by using morphological image processing, and determining the binarized bright-dark stripe width of the first internal thread image and the binarized bright-dark stripe width of the second internal thread image.

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

In view of the fact that certain noise exists in the binarized bright-dark fringes, the accuracy of determining the width of the fringes is further improved, so that the accuracy of geometric parameters of the internal threads is improved, and noise reduction processing is conducted on the binarized bright-dark fringes of the extracted first internal thread image and the binarized bright-dark fringes of the second internal thread image through mean value blurring and closing operation respectively, so that the binarized bright-dark fringes of the first internal thread image and the binarized bright-dark fringes of the second internal thread image after noise reduction are obtained.

Finally, dividing and marking the binarized bright-dark stripes of the first internal thread image after noise reduction by morphological image processing respectively, and determining the width of the binarized bright-dark stripes of the first internal thread image; and dividing and marking the binarized bright-dark stripes of the second internal thread image after noise reduction by using morphological image processing, and determining the width of the binarized bright-dark stripes of the second internal thread image.

In the embodiment of the invention, a first group of internal thread partial images are spliced to form a first internal thread image, a second group of internal thread partial images are spliced to form a second internal thread image, the binarization bright-dark stripe of the first internal thread image and the binarization bright-dark stripe of the second internal thread image are extracted by utilizing self-adaptive thresholds, the extracted binarization bright-dark stripe of the first internal thread image and the binarization bright-dark stripe of the second internal thread image are respectively subjected to noise reduction through mean blurring and closing operation, the binarization bright-dark stripe of the first internal thread image and the binarization bright-dark stripe of the second internal thread image after noise reduction are obtained, the binarization bright-dark stripe of the first internal thread image and the binarization bright-dark stripe of the second internal thread image after noise reduction are respectively subjected to segmentation and marking through morphological image processing, and the binarization bright-dark stripe width of the first internal thread image and the binarization bright-dark stripe width of the second internal thread image are determined. According to the embodiment of the invention, the binarization bright-dark stripe of the internal thread image is extracted by utilizing the self-adaptive threshold value, the binarization bright-dark stripe of the internal thread image is reduced in noise through mean value blurring and closing operation, and finally, the binarization bright-dark stripe width of the internal thread image is determined by utilizing morphological image processing, so that the accuracy of determining the stripe width can be improved, and the accuracy of geometric parameters of the internal thread is further improved.

Fig. 4 shows a flow of implementing step 103 in the binocular vision-based internal thread form geometric parameter measurement method according to the embodiment of the present invention, and for convenience of description, only the relevant parts of the embodiment of the present invention are shown, which is described in detail below:

in an embodiment of the present invention, in order to improve accuracy of determining the width of the internal thread profile stripe, and further improve measurement accuracy of geometric parameters of the internal thread, as shown in fig. 4, step 103, determining the profile image parameters of the internal thread according to the binary bright-dark stripe width of the first internal thread image of the bright-dark stripe width and the binary bright-dark stripe width of the second internal thread image of the bright-dark stripe width by using a projection relationship between the profile stripe width of the internal thread and the profile image parameters of the internal thread under a photographing angle, includes:

step 401, aligning the binarized bright-dark stripes of the first internal thread image and the binarized bright-dark stripes of the second internal thread image by using the initial position or the final position of the internal thread to obtain a plurality of groups of first thread pattern stripe width sequences of the first internal thread image which are corresponding to a first preset shooting angle and are formed by a plurality of stripes, and a plurality of groups of second thread pattern stripe width sequences of the second internal thread image which are corresponding to a second preset shooting angle and are formed by a plurality of stripes;

Step 402, determining a first dental profile image parameter and a second dental profile image parameter of the internal thread according to the plurality of sets of first dental profile stripe width sequences and the plurality of sets of second dental profile stripe width sequences by using a projection relationship between the dental profile stripe width of the internal thread and the dental profile image parameter of the internal thread under the shooting angle.

When the tooth type image parameters of the internal thread are specifically determined, the binarization bright-dark stripes of the first internal thread image and the binarization bright-dark stripes of the second internal thread image are aligned according to the starting position or the ending position of the internal thread, so that the data are kept consistent. And obtaining a plurality of groups of first thread pattern stripe width sequences of the first internal thread images which correspond to the first preset shooting angle alpha 1 and are formed by a plurality of stripes, and a plurality of groups of second thread pattern stripe width sequences of the second internal thread images which correspond to the second preset shooting angle alpha 2 and are formed by a plurality of stripes. For example, the binarized bright-dark stripes of the first internal thread image and the binarized bright-dark stripes of the second internal thread image are aligned at the initial position of the internal thread to obtain a first thread pattern width sequence { [ Ll ', lt ', lr ', ld } ' of the first internal thread image with a plurality of groups of 4 stripes as one group ' ] _i }. Wherein, ll ', lt', lr 'and Ld' respectively represent the first left-tooth side image stripe width, the first crest image stripe width, the first right-tooth side image stripe width and the first root image stripe width of the i-th group of the first internal thread image. And a second thread pattern width sequence { [ Ll ], lt ', lr ', ld ' of a second internal thread image of a plurality of sets of 4 stripes as one set "] _i }. Wherein, ll ", lt", lr ", and Ld" respectively represent a second left-tooth side image stripe width, a second crest image stripe width, a second right-tooth side image stripe width, and a second root image stripe width of the i-th group second internal thread image.

Further, the correspondence between the width of the ridge of the internal thread and the profile image parameter of the internal thread at the photographing angle shown in fig. 1 to 5 is used to determine the profile image parameter of the internal thread by the following formula:

or->

Or->

Wherein, ll, lt, lr and Ld respectively represent left-side image parameters, crest image parameters, right-side 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 a first left-tooth side image stripe width, a first crest image stripe width, a first right-tooth side image stripe width, and a first root image stripe width of the i-th group of first internal thread images, and Lh represents a tooth height image parameter; α1 and α2 represent a first preset photographing angle and a second preset photographing angle, respectively, and θl and θr represent a left flank angle of the internal thread and a right flank angle of the internal thread, respectively.

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

In the embodiment of the invention, the binarization bright-dark stripes of the first internal thread image and the binarization bright-dark stripes of the second internal thread image are aligned by the starting position or the ending position of the internal thread to obtain a plurality of groups of first thread pattern stripe width sequences of the first internal thread image which correspond to a first preset shooting angle and are formed by a plurality of stripes as a group, and a plurality of groups of second thread pattern stripe width sequences of the second internal thread image which correspond to a second preset 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, the first thread pattern image parameters and the second thread pattern image parameters of the internal thread are determined by utilizing the corresponding relation between the thread pattern stripe widths of the internal thread and the thread pattern image parameters of the internal thread under the shooting angle, so that the accuracy of determining the thread pattern stripe widths of the internal thread can be improved, and the measurement accuracy of the internal thread geometric parameters can be improved by using the average value of two formulas for part of the parameters.

Fig. 5 shows a flow of implementation of step 104 in the binocular vision-based internal thread form geometric parameter measurement method according to the embodiment of the present invention, and for convenience of description, only the relevant parts of the embodiment of the present invention are shown, which is described in detail below:

in an embodiment of the present invention, in order to further improve the measurement accuracy of the geometric parameters of the internal thread, as shown in fig. 5, step 104 of determining the actual parameters of the internal thread according to the width of the ridge and the pitch length of the internal thread includes:

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

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

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

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

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

For example, if the left-hand image parameter of the internal thread, the crest image parameter of the internal thread, the right-hand image parameter of the internal thread, and the root image parameter of the internal thread are determined to be 66, 50, 65, and 20, respectively, the thread length is 2.5 mm, and the sum of the image parameters of the corresponding thread forms of the thread pitch length is 66+50+65+20=201, the actual width of the left-hand side of the internal thread can be determined to be based on the above formulaMillimeter. 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 formulas. So far, the accurate measurement of the internal thread geometric parameters is realized.

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

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

In the embodiment of the invention, the screw pitch length of the internal thread is determined according to the screw thread density of the binarized bright-dark stripes of the first internal thread image and the screw thread density of the binarized bright-dark stripes of the second internal thread image by utilizing the pre-calibrated screw thread pitch corresponding relation, and the actual tooth shape parameters of the internal thread are determined according to the tooth shape image parameters of the internal thread, the screw pitch length and the sum of the image parameters of the tooth shapes corresponding to the screw pitch length, so that the measurement accuracy of the geometric parameters of the internal thread can be further improved.

It should be noted that, based on the first preset shooting angle being 0 °, the relative ratio of the lengths of each part of the tooth form can be directly obtained, and then shooting is performed at the second preset shooting angle (not being 0 °; or based on the fact that the second preset shooting angle is 0 degree, the relative ratio of the lengths of all parts of the dental form is directly obtained, and then shooting is carried out at the first preset shooting angle (which is not 0 degree), so that the measurement of the geometric parameters of the internal thread is respectively realized, and the measurement accuracy of the geometric parameters of the internal thread is poor when the measurement is compared with the measurement accuracy of the geometric parameters of the internal thread which are obtained by the fact that the first preset shooting angle is symmetrical with the second preset shooting angle. In addition, the first group of internal thread partial images or the second group of internal thread partial images obtained through shooting can be used for directly calculating each internal thread partial image without image stitching so as to obtain the profile parameters of the internal thread, and then sequencing is carried out to obtain the profile parameters of each thread of the whole threaded hole.

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

Fig. 6 shows functional modules of the binocular vision-based internal thread type geometric parameter measuring device according to the embodiment of the present invention, and for convenience of explanation, only the portions relevant to the embodiment of the present invention are shown, and the details are as follows:

referring to fig. 6, each module included in the binocular vision-based internal thread form geometric parameter measuring device is configured to perform each step in the corresponding embodiment of fig. 1, and detailed descriptions in fig. 1 and the corresponding embodiment of fig. 1 are omitted herein. In the embodiment of the invention, the device for measuring the geometric parameters of the internal thread profile based on binocular vision comprises a local image shooting module 601, a stripe width determining module 602, an image parameter determining module 603 and a profile parameter determining module 604.

The local image capturing module 601 is configured to capture a first set of internal thread local images in steps at a first preset capturing angle and a second set of internal thread local images in steps at a second preset capturing angle according to a step length by using the endoscope probe.

The stripe width determining module 602 is configured to determine a binarized bright-dark stripe width of the bright-dark stripe width first internal thread image and a binarized 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 partial images, and the second internal thread image is formed by splicing a second group of internal thread partial images.

The image parameter determining module 603 is configured to determine a dental image parameter of the internal thread according to the binarized light and dark stripe width of the first internal thread image with the light and dark stripe width and the binarized light and dark stripe width of the second internal thread image with the projection relationship between the dental stripe width of the internal thread and the dental image parameter of the internal thread at the shooting angle.

The profile parameter determining module 604 is configured to determine the actual profile parameter of the internal thread according to the profile image parameter and the pitch length of the internal thread.

In the embodiment of the present invention, the local image capturing module 601 captures a first group of internal thread local images in steps at a first preset capturing angle and a second group of internal thread local images in steps at a second preset capturing angle according to the step length by using the endoscope probe; the stripe width determining module 602 determines a binarized light and dark stripe width of the first internal thread image and a binarized light and dark stripe width of the second internal thread image; the image parameter determining module 603 determines a profile image parameter of the internal thread according to the binarized light and dark stripe width of the first internal thread image with the light and dark stripe width and the binarized light and dark stripe width of the second internal thread image with the projection relationship between the profile stripe width of the internal thread and the profile image parameter of the internal thread under the shooting angle; the profile parameter determination module 604 determines the actual profile parameters of the internal thread based on the profile image parameters and the 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 a small-size deep hole of an internal thread is realized; and the reliable tooth form parameters can be obtained for the thread defects along the trend statistical average of the internal threads, so that the measurement accuracy of the internal thread tooth form parameters is improved.

In a preferred embodiment, in order to improve accuracy of capturing the internal thread image, further accuracy of measuring the internal thread geometric parameter is set according to the number of threads included in the captured internal thread partial image.

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

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

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 photographing angle is not more than 90 °, and the sum of the flank angle of the internal thread and the absolute value of the second preset photographing angle is not more 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 mirror of the endoscope probe comprises two limiting angles, and the view angle of the variable angle plane mirror of the endoscope probe is switched through the link mechanism.

Fig. 7 shows a schematic structural diagram of a local image capturing module 601 in the binocular vision-based internal thread type geometric parameter measuring device according to an embodiment of the present invention, and for convenience of explanation, only the portions related to the embodiment of the present invention are shown, which are described in detail below:

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

A first partial image photographing unit 701 for photographing a first group of internal thread partial images stepwise from a start position to a final position of the internal thread at a first preset photographing angle according to a stepping length using an endoscope probe having a head mounted variable angle plane mirror; the first preset shooting angle is an acute angle formed by the intersection of a reflection light plane on a variable angle plane reflecting mirror of the endoscope probe and a vertical middle axis surface of the internal thread, wherein the first incidence light plane is located at a starting position and a final position along the horizontal middle axis surface of the internal thread, and the acute angle formed by the first incidence light plane and a normal plane of the variable angle plane reflecting mirror is an acute angle.

A second partial image photographing unit 702 for photographing a second group of internal thread partial images stepwise from the ending position to the starting position of the internal thread at a second preset photographing angle according to a stepping length using an endoscope probe having a variable angle plane mirror mounted on a head; the second preset shooting angle is an acute angle formed by the intersection of a reflection light plane on a variable angle plane reflecting mirror of the endoscope probe and a vertical middle axis surface of the internal thread, and the angle formed by the second incidence light plane and a normal plane of the variable angle plane reflecting mirror is an acute angle.

In the embodiment of the present invention, the first partial image capturing unit 701 captures a first group of internal thread partial images stepwise from the start position to the end position of the internal thread at a first preset capturing angle α1 according to a step length by using an endoscope probe having a variable angle plane mirror mounted on the head; the first preset shooting angle alpha 1 is an acute included angle formed by intersecting a reflected light plane on a variable angle plane reflector of the endoscope probe and a vertical middle axis surface of the internal thread along a first incident light plane of a starting position and a final position of the horizontal middle axis surface of the internal thread; the second partial image photographing unit 702 photographs a second group of partial images of the internal thread in steps from the ending position to the starting position of the internal thread by a second preset photographing angle α2 according to a step length by using the endoscope probe with the variable angle plane mirror mounted on the head, the second preset photographing angle α2 being an acute angle formed by intersecting a reflected light plane on the variable angle plane mirror of the endoscope probe and a vertical middle axis plane of the internal thread along the ending position to the starting position of the horizontal 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 partial image of the internal thread can be improved, and the measurement accuracy of the geometric parameter of the internal thread can be further improved.

Fig. 8 shows a schematic structure of a stripe width determining module 602 in the binocular vision-based internal thread form geometric parameter measuring apparatus according to an embodiment of the present invention, and for convenience of explanation, only the portions related to the embodiment of the present invention are shown, which are described in detail below:

in an embodiment of the present invention, in order to improve accuracy of determining the width of the stripe, and further improve accuracy of geometric parameters of the internal thread, referring to fig. 8, each unit included in the stripe width determining module 602 is used to perform each step in the corresponding embodiment of fig. 3, and specifically please refer to fig. 3 and related descriptions in the corresponding embodiment of fig. 3, which 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 noise reducing unit 803, and a stripe width determining unit 804.

And the stitching unit 801 is configured to stitch the first set of partial images of the internal thread to form a first internal thread image, and stitch the second set of partial images of the internal thread to form a second internal thread image.

The stripe extracting unit 802 is 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 the adaptive threshold value, respectively.

The noise reduction unit 803 is configured to reduce noise of the binarized bright-dark stripe of the extracted first internal thread image and the binarized bright-dark stripe of the second internal thread image by mean value blurring and closing operation, respectively, to obtain a binarized bright-dark stripe of the noise-reduced first internal thread image and a binarized bright-dark stripe of the second internal thread image;

the stripe width determining unit 804 is configured to divide and mark the binarized bright-dark stripe of the first internal thread image and the binarized bright-dark stripe of the second internal thread image after noise reduction by using morphological image processing, respectively, and determine the binarized bright-dark stripe width of the first internal thread image and the binarized bright-dark stripe width of the second internal thread image.

In the embodiment of the present invention, the stitching unit 801 respectively stitches the first set of internal thread partial images to form a first internal thread image, and stitches the second set of internal thread partial images to form a second internal thread image, the stripe extracting unit 802 respectively extracts the binarized bright-dark stripe of the first internal thread image and the binarized bright-dark stripe of the second internal thread image by using adaptive thresholds, the noise reducing unit 803 respectively performs noise reduction on the extracted binarized bright-dark stripe of the first internal thread image and the binarized bright-dark stripe of the second internal thread image by means of mean blurring and closing operation, so as to obtain the binarized bright-dark stripe of the first internal thread image and the binarized bright-dark stripe of the second internal thread image after noise reduction, and the stripe width determining unit 804 respectively performs segmentation and marking on the binarized bright-dark stripe of the first internal thread image and the binarized bright-dark stripe of the second internal thread image after noise reduction by using morphological image processing, so as to determine the binarized bright-dark stripe width of the first internal thread image and the binarized bright-dark stripe width of the second internal thread image. According to the embodiment of the invention, the stripe extraction unit 802 extracts the binarized bright-dark stripes of the internal thread image by using the self-adaptive threshold, the noise reduction unit 803 reduces the noise of the binarized bright-dark stripes of the internal thread image by means of mean blurring and closing operation, and finally the stripe width determination unit 804 determines the binarized bright-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 accuracy of geometric parameters of the internal thread can be further improved.

Fig. 9 shows a schematic structural diagram of an image pixel determining module 603 in the binocular vision-based internal thread type geometric parameter measuring device according to an embodiment of the present invention, and for convenience of explanation, only the portions relevant to the embodiment of the present invention are shown, which are described in detail below:

in an embodiment of the present invention, in order to improve the accuracy of determining the width of the internal thread profile, 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 execute each step in the corresponding embodiment of fig. 4, and detailed descriptions in fig. 4 and the corresponding embodiment of fig. 4 will not be repeated herein. In the embodiment of the present invention, the image parameter determining module 603 includes a stripe alignment unit 901 and an image parameter determining unit 902.

The stripe alignment unit 901 is configured to align the binarized bright-dark stripes of the first internal thread image and the binarized bright-dark stripes of the second internal thread image with a start position or an end position of the internal thread, to obtain a plurality of groups of first thread type stripe width sequences of the first internal thread image corresponding to a first preset shooting angle and a plurality of groups of second thread type stripe width sequences of the second internal thread image corresponding to a second preset shooting angle, wherein the first thread type stripe width sequences correspond to a first preset shooting angle and the second thread type stripe width sequences correspond to a second preset shooting angle.

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

In the embodiment of the present invention, the stripe alignment unit 901 aligns the binarized bright-dark stripes of the first internal thread image and the binarized bright-dark stripes of the second internal thread image with the start position or the end position of the internal thread, so as to obtain a plurality of groups of first thread pattern stripe width sequences of the first internal thread image corresponding to a first preset shooting angle and a plurality of groups of second thread pattern stripe width sequences of the second internal thread image corresponding to a second preset shooting angle, and the image parameter determining unit 902 determines the first thread pattern image parameters and the second thread pattern image parameters of the internal thread according to the projection relationship between the thread pattern stripe widths of the internal thread and the thread pattern image parameters of the internal thread under the shooting angle, so as to improve the accuracy of determining the thread pattern image parameters of the internal thread, and further improve the measurement accuracy of the internal thread geometric parameters.

Fig. 10 shows a schematic structural diagram of a tooth form parameter determining module 604 in the binocular vision-based internal thread tooth form geometric parameter measuring device according to an embodiment of the present invention, and for convenience of explanation, only the portions relevant to the embodiment of the present invention are shown, and the details are 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 dental parameter determining module 604 is configured to perform each step in the corresponding embodiment of fig. 5, and specifically please refer to fig. 5 and the related description in the corresponding embodiment of fig. 5, which are not repeated herein. In the embodiment of the present invention, the dental model parameter determining module 604 includes a pitch length determining unit 1001 and a dental model parameter determining unit 1002.

The thread pitch length determining unit 1001 is configured to determine the thread pitch length of the internal thread according to the thread density of the binarized bright-dark stripe of the first internal thread image and the thread density of the binarized bright-dark stripe of the second internal thread image by using a pre-calibrated thread pitch correspondence.

A dental form parameter determining unit 1002, configured to determine a dental form actual parameter of the internal thread according to a dental form image parameter of the internal thread, a pitch length, and a sum of dental form image parameters corresponding to the pitch length; the sum of the image parameters of the tooth form corresponding to the pitch length is the sum of the image parameters of the tooth crest, the left tooth side, the right tooth side and the tooth root of the tooth form 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-dark stripe of the first internal thread image and the thread density of the binarized bright-dark stripe of the second internal thread image by using a pre-calibrated thread pitch correspondence, and the thread form parameter determining unit 1002 determines the actual thread form parameter of the internal thread according to the thread form image parameter of the internal thread, the sum of the thread form parameters corresponding to the pitch length and the thread form 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 method comprises the steps that an endoscope probe is used for shooting internal threads, visual measurement of threads in a small hole can be achieved only by manufacturing the small-diameter endoscope probe for the small threaded hole, and laser word lines are shot at a variable angle outside the threaded hole after being projected outside the threaded hole, so that small hole detection cannot be achieved;

(2) The pictures shot by the method are two-dimensional projections of the threads, and can be subjected to transverse statistical average along the trend of the threads, so that reliable thread profile parameters can be obtained for defect positions such as thread jumping angles, cracks and the like; meanwhile, the widths of all parts of the screw teeth can be corrected by using texture features, and the screw teeth have universality for the conditions of chamfering, non-trapezoid screw teeth and the like. In addition, the two-dimensional image can be used for detecting defects of the thread surface, and if rotation control is added in the shooting process, all the shape information of the whole internal thread surface can be obtained.

In summary, in the embodiment of the present invention, according to the step length, the endoscope probe is utilized to step-shoot the first group of internal thread partial images at the first preset shooting angle, and step-shoot the second group of internal thread partial images at the second preset shooting angle; respectively determining the binarization bright-dark stripe width of the first internal thread image with the bright-dark stripe width and the binarization bright-dark stripe width of the second internal thread image with the bright-dark stripe width; according to the binarization light and dark stripe width of the first internal thread image and the binarization light and dark stripe width of the second internal thread image, determining the profile image parameters of the internal thread by utilizing the projection relation between the profile stripe width of the internal thread and the profile image parameters of the internal thread under the shooting angle; and determining the actual parameters of the internal thread tooth form according to the internal thread tooth form image parameters and the thread pitch length. According to the embodiment of the invention, an endoscope probe is used for shooting an internal thread image, so that the measurement of a small-size deep hole of an internal thread is realized; and the reliable tooth form parameters can be obtained for the thread defects along the trend statistical average of the internal threads, so that the measurement accuracy of the internal thread tooth form parameters is improved.

It will be appreciated by those skilled in the art that 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 is 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 flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations 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 foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims

1. The method for measuring the geometric parameters of the internal thread profile based on binocular vision is characterized by comprising the following steps of:

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

wherein, the variable angle plane speculum has been installed to the head of endoscope probe, utilizes the endoscope probe to shoot first group internal thread partial image with first default shooting angle step by step according to step length to and shoot second group internal thread partial image with second default shooting angle step by step, includes:

Using an endoscope probe with a head provided with a variable angle plane reflecting mirror to step and shoot a first group of internal thread partial images from the initial position to the final position of the internal thread according to the step length at a first preset shooting angle; the first preset shooting angle is an acute angle formed by intersecting a reflection light plane on a variable angle plane reflecting mirror of the endoscope probe and a vertical middle axis surface of the internal thread along the initial position of the horizontal middle axis surface of the internal thread and the first incident light plane at the final position, and the angle formed by the first incident light plane and the normal plane of the variable angle plane reflecting mirror is an acute angle;

using an endoscope probe with a head provided with a variable angle plane reflecting mirror to step and shoot a second group of internal thread partial images from the ending position to the starting position of the internal thread according to the step length at a second preset shooting angle; the second preset shooting angle is an acute included angle formed by intersecting a reflected light plane on a variable angle plane reflector of the endoscope probe and a vertical middle axis surface of the internal thread along a second incident light plane from a final position to a starting position of the horizontal middle axis surface 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;

wherein the method further comprises:

Setting the stepping length according to the number of threads contained in the shot internal thread partial image; and/or

The first preset shooting angle is the same as the second preset shooting angle, and the directions are opposite; and/or

The overlapping part of two adjacent frames of internal thread partial images in the first group of internal thread partial images is smaller than the pitch of the internal thread, and the overlapping part of two adjacent frames of internal thread partial images in the second group of internal thread partial images is smaller than the 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 photographing angle is not more than 90 DEG, and the sum of the flank angle of the internal thread and the absolute value of the second preset photographing angle is not more than 90 deg.

2. The binocular vision-based internal thread type geometrical parameter measurement method of claim 1, wherein the variable angle plane mirror of the endoscope probe comprises two limiting angles, and the viewing angle of the variable angle plane mirror of the endoscope probe is switched by a link mechanism.

3. The binocular vision-based internal thread type geometric parameter measuring method of claim 1, wherein the binarized bright-dark stripe width of the first internal thread image and the binarized bright-dark stripe width of the second internal thread image of the bright-dark stripe width are respectively determined; the first internal thread image is formed by splicing a first group of internal thread partial images, and the second internal thread image is formed by splicing a second group of internal thread partial images, and the method comprises the following steps:

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

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

noise reduction is carried out on the extracted binarization bright-dark stripes of the first internal thread image and the extracted binarization bright-dark stripes of the second internal thread image through mean blurring and closing operation respectively, and the binarization bright-dark stripes of the first internal thread image and the binarization bright-dark stripes of the second internal thread image after noise reduction are obtained;

dividing and marking the binarized bright-dark stripes of the first internal thread image and the binarized bright-dark stripes of the second internal thread image after noise reduction by morphological image processing respectively, and determining the binarized bright-dark stripe width of the first internal thread image and the binarized bright-dark stripe width of the second internal thread image.

4. The binocular vision-based internal thread profile geometry measuring method of claim 1, wherein determining the profile image parameters of the internal thread using the projection relationship between the profile stripe width of the internal thread and the profile image parameters of the internal thread at the photographing angle according to the binarized light-dark stripe width of the first internal thread image and the binarized light-dark stripe width of the second internal thread image, comprises:

Aligning the binarization bright-dark stripes of the first internal thread image and the binarization bright-dark stripes of the second internal thread image by using the starting position or the ending position of the internal thread to obtain a plurality of groups of first thread pattern stripe width sequences of the first internal thread image which are corresponding to a first preset shooting angle and are formed by a plurality of stripes as a group, and a plurality of groups of second thread pattern stripe width sequences of the second internal thread image which are corresponding to a second preset shooting angle and are formed by a plurality of stripes;

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

5. The binocular vision-based internal thread profile geometry parameter measurement method of claim 1, wherein determining the profile actual 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 pre-calibrated thread pitch corresponding relation according to the thread density of the binarized bright-dark stripes of the first internal thread image and the thread density of the binarized bright-dark stripes of the second internal thread image;

Determining the actual parameters of the tooth form of the internal thread according to the sum of the tooth form image parameters corresponding to the screw pitch length and the screw pitch length; the sum of the image parameters of the tooth form corresponding to the pitch length is the sum of the image parameters of the tooth crest, the left tooth side, the right tooth side and the tooth root of the tooth form corresponding to the pitch length.

6. An internal thread form geometric parameter measuring device based on binocular vision, characterized by comprising:

The tooth form parameter determining module is used for determining the actual tooth form parameters of the internal thread according to the tooth form image parameters and the screw pitch length of the internal thread;

wherein, the head of endoscope probe has installed the variable angle plane speculum, the local image shooting module is specifically used for:

Wherein the device is also used for:

7. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the binocular vision-based internal thread form geometrical parameter measuring method of any one of claims 1 to 5 when executing the computer program.

8. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program for executing the binocular vision-based internal thread form geometric parameter measuring method of any one of claims 1 to 5.