Method for determining optimal incident attitude of line structured light for measuring involute tooth surface

Abstract

The present invention discloses a method for determining the optimal incident attitude of a line structured light for measuring an involute tooth surface, including: designing a line structured light three-dimensional measuring instrument according to measurement requirements, and constructing a digital twin model based on digital twin technology; measuring the error information of the line structured light three-dimensional measuring instrument and establishing an error system; constructing an algorithm for analyzing the specular reflection characteristics to map the specular reflection effect without considering the tooth surface roughness; constructing an algorithm for analyzing the diffuse reflection characteristics under the action of roughness to map the diffuse reflection effect; based on the digital twin model under the error system, simulating the reflection characteristics of the line structured light at different angles according to the specular reflection effect and the diffuse reflection effect; using an imaging quality evaluation method to evaluate the imaging of each angle, determining the optimal incident attitude and adjusting the line structured light three-dimensional measuring instrument. Through the technical solution of the present invention, the optimal incident attitude of the line structured light can be determined, so as to iteratively optimize and adjust the measuring attitude of the line structured light three-dimensional measuring instrument.

Description

Technical Field

[0001] The present invention relates to the field of measurement technology, and particularly to a method for determining the optimal incident attitude of a line structured light for measuring an involute tooth surface. Background Art

[0002] Currently, by using the line structured light measurement method, three-dimensional information of the gear surface can be quickly obtained. Compared with the traditional contact measurement method, the detection efficiency is greatly improved. However, when using the optical measurement method, its measurement accuracy is easily affected by the incident pose of the line structured light, and the occlusion between adjacent teeth limits the ability to obtain information on the convex surface and the reflective surface of the gear.

[0003] The principle of line structured light measurement is as Figure 1 shown in the left figure. The laser source emits a laser beam, which forms a laser plane through a cylindrical lens. The laser plane forms an intersection line with the measured surface, and the information of the intersection line is recorded by the photosensitive element through the lens for quickly obtaining the contour of the target surface. Figure 1 The gray area in the right figure is the effective measurement range of the sensor. The incident angle of the sensor and the working distance will limit the acquisition of tooth surface information.

[0004] From Figure 2 the experimental results, the data in the tooth root area at x = 4 mm cannot be effectively obtained. The reason is that there are multiple reflections in the projection of the laser line in the tooth root area, which limits the acquisition of effective information on the tooth surface at this place. For large gears, the tooth pitch is large, the incident angle range of the laser plane is also large, and the light reflection effect at the tooth root part is small, so the measurement difficulty is not high. However, for the measurement of small module gears, the incident attitude of the laser plane will seriously affect the measurement result.

[0005] At present, the three-dimensional measurement accuracy of gear line structured light is limited by the complex geometric characteristics of the gear itself. The occlusion between adjacent teeth will cause occlusion of the structured light, limiting the incident attitude of the structured light plane; the curvatures of different parts of the tooth surface are different and change violently, and the tooth root and tooth tip are generally non-involute tooth surfaces, making the reflection law of the structured light on the complete tooth surface inconsistent. Coupled with possible modification and profile modification, the reflection complexity is increased; due to the narrow space near the tooth root, multiple reflections of the measurement light occur, resulting in invalid data that is difficult to distinguish and eliminate. The above factors limit the three-dimensional measurement accuracy of gear line structured light to a certain extent. Summary of the Invention

[0006] To address the above problems, the present invention provides a method for determining the optimal incident attitude of line structured light for measuring an involute tooth surface. By constructing a digital twin model of a gear line structured light three-dimensional measuring instrument, the specular and diffuse reflection characteristics of the involute tooth surface with respect to the line structured light are analyzed through this model. In addition, an imaging quality evaluation method based on a camera field-of-view threshold cut-off strategy is used to analyze the intensity and range of the reflected light entering the camera, determine the optimal incident attitude of the line structured light, and thus iteratively optimize and adjust the measuring attitude of the line structured light three-dimensional measuring instrument.

[0007] To achieve the above object, the present invention provides a method for determining the optimal incident attitude of line structured light for measuring an involute tooth surface, including:

[0008] Design a line structured light three-dimensional measuring instrument for the involute tooth surface of a gear according to the actual measurement requirements;

[0009] Based on digital twin technology, construct a digital twin model corresponding to the line structured light three-dimensional measuring instrument;

[0010] Measure the geometric error, assembly error, sensor installation error, and inherent error of the line structured light three-dimensional measuring instrument, as well as the overall error of the measurement system, as error information;

[0011] Establish an error system for the digital twin model according to the error information;

[0012] Construct an analysis algorithm for the specular reflection characteristics of the involute tooth surface with respect to the line structured light, and map the specular reflection effect of the involute tooth surface on the line structured light in the actual measurement process without considering the tooth surface roughness;

[0013] Construct an analysis algorithm for the diffuse reflection characteristics of the involute tooth surface with respect to the structured light plane under the action of roughness, and map the diffuse reflection effect of the involute tooth surface on the line structured light in the actual measurement process;

[0014] Based on the digital twin model under the error system, according to the specular reflection effect and the diffuse reflection effect, simulate and analyze the reflection characteristics of the involute tooth surface with respect to the line structured light at different angles; use an imaging quality evaluation method based on a camera field-of-view threshold cut-off strategy to evaluate the imaging at each angle, and evaluate to determine the optimal incident attitude of the line structured light for measuring the involute tooth surface;

[0015] Adjust the line structured light three-dimensional measuring instrument to the optimal incident attitude.

[0016] In the above technical solution, preferably, the specific process of designing a line structured light three-dimensional measuring instrument for the involute tooth surface of a gear according to the actual measurement requirements includes:

[0017] According to the actual measurement requirements for gears, the appropriate size of the line-structured light three-dimensional measurement instrument is designed, and the physical components are processed and assembled to obtain the line-structured light three-dimensional measurement instrument.

[0018] In the above technical solution, preferably, the specific process of establishing the error system of the digital twin model includes:

[0019] According to the error information of the line-structured light three-dimensional measurement instrument, a measurement error and uncertainty calculation model is constructed based on the digital twin model;

[0020] Based on the digital twin model, a sensor signal error model, a static error model, and a dynamic error model of the measurement instrument are established.

[0021] In the above technical solution, preferably, the specific process of using the imaging quality evaluation method based on the camera field of view threshold cut-off strategy to evaluate the imaging of each angle and evaluate and determine the best incident posture of the line-structured light for measuring the involute tooth surface includes:

[0022] Based on the camera field of view threshold cut-off strategy, an analysis algorithm for the specular reflection and diffuse reflection characteristics of the involute tooth surface to the line-structured light is established, and the reflection effect of the involute tooth surface to the line-structured light is dynamically obtained and analyzed. The intensity and range of the reflected light entering the camera field of view are quantitatively analyzed, and the imaging quality of the images at different incident angles is evaluated according to the ineffective reflection intensity and the proportion of ineffective reflection in the entire image;

[0023] Evaluate the best imaging quality at different incident angles, and determine the best incident posture of the line-structured light in the line-structured light three-dimensional measurement structure according to the incident angle corresponding to the best imaging quality.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: By constructing a digital twin model of the gear line-structured light three-dimensional measurement instrument, the specular reflection and diffuse reflection characteristics of the involute tooth surface to the line-structured light are analyzed through this model. In addition, based on the imaging quality evaluation method of the camera field of view threshold cut-off strategy, the intensity and range of the reflected light entering the camera are analyzed to determine the best incident posture of the line-structured light, so as to iteratively optimize and adjust the measurement posture of the line-structured light three-dimensional measurement instrument. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the principle of line-structured light measurement;

[0026] Figure 2 is Figure 1 a schematic diagram of the measurement experimental results of the measurement method shown;

[0027] Figure 3 It is a schematic flowchart of the method for determining the best incident posture of the line-structured light for measuring the involute tooth surface disclosed in an embodiment of the present invention;

[0028] Figure 4 Schematic diagram of the engineering assembly of a line-structured light three-dimensional measurement instrument disclosed in an embodiment of the present invention;

[0029] Figure 5 Schematic diagram of a three-dimensional measurement model of a gear disclosed in an embodiment of the present invention;

[0030] Figure 6 Schematic diagram of the practice mode of a method for determining the optimal incident attitude of a line-structured light for measuring an involute tooth surface according to the present invention.

[0031] In the figure, the corresponding relationship between each component and the reference numeral is as follows:

[0032] 1. Optical platform; 2. High-precision turntable; 3. Flange and three-jaw chuck; 4. Involute gear; 5. Line-structured light plane; 6. Line-structured light sensor; 7. Index plate; 8. XZ linear module. Detailed implementation manners

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] The following further describes the present invention in detail with reference to the accompanying drawings:

[0035] As Figure 3 shown, according to a method for determining the optimal incident attitude of a line-structured light for measuring an involute tooth surface provided by the present invention, it includes:

[0036] Design a line-structured light three-dimensional measurement instrument for the involute tooth surface of a gear according to actual measurement requirements;

[0037] Based on digital twin technology, construct a digital twin model corresponding to the line-structured light three-dimensional measurement instrument; measure the form error, assembly error, sensor installation error, and inherent error of the line-structured light three-dimensional measurement instrument, as well as the overall error of the measurement system, as error information;

[0038] Establish an error system for the digital twin model according to the error information;

[0039] Construct an algorithm for analyzing the specular reflection characteristics of an involute tooth surface against line structured light, and map the specular reflection of the involute tooth surface against line structured light during the actual measurement process without considering the tooth surface roughness; construct an algorithm for analyzing the diffuse reflection characteristics of the involute tooth surface against the structured light plane under the action of roughness, and map the diffuse reflection of the involute tooth surface against line structured light during the actual measurement process;

[0040] Based on the digital twin model under the error system, according to the specular reflection and diffuse reflection, simulate and analyze the reflection characteristics of the involute tooth surface against line structured light at different angles;

[0041] Use the imaging quality evaluation method based on the camera field of view threshold cut-off strategy to evaluate the imaging of each angle, and evaluate to determine the best incident attitude of the line structured light for measuring the involute tooth surface;

[0042] Adjust the line structured light three-dimensional measuring instrument to the best incident attitude.

[0043] In this embodiment, by constructing the digital twin model of the gear line structured light three-dimensional measuring instrument, analyze the specular reflection and diffuse reflection characteristics of the involute tooth surface against line structured light through this model. In addition, based on the imaging quality evaluation method of the camera field of view threshold cut-off strategy, analyze the intensity and range of the reflected light entering the camera, and determine the best incident attitude of the line structured light, so as to iteratively optimize and adjust the measuring attitude of the line structured light three-dimensional measuring instrument.

[0044] Specifically, the purpose of the present invention is to find a suitable incident attitude of the line structured light plane, so that the line structured light is reflected into the camera as much as possible, the reflection intensity of the line structured light in the length direction is as uniform as possible, and the depth of each point is as close as possible to improve the three-dimensional measurement accuracy of the gear line structured light.

[0045] As Figure 4 shown, among them, the line structured light three-dimensional measuring instrument includes an optical platform 1, a high-precision turntable 2, a flange and a three-jaw chuck 3, an involute gear 4, a line structured light plane 5 and a line structured light sensor 6, a dividing plate 7 and an XZ linear module 8. The high-precision turntable 2 is used to provide the rotational motion during the measurement of the involute gear 4, the line structured light sensor 6 is used to collect the information of the involute tooth surface, the dividing plate 7 is used to adjust the incident attitude of the line structured light sensor 6, and the XZ linear module 8 is used to adjust the relative position relationship between the line structured light sensor 6 and the involute gear 4, so that the involute gear 4 is within the measurement range of the line structured light sensor 6.

[0046] The gear three-dimensional measurement model is as shown in the appendix Figure 5As shown, (A) involute gears 4 generally include involute spur gears and involute helical gears. (A1) is the measured involute tooth surface. During the measurement process, the reflection characteristics of the involute tooth surface to structured light can be divided into three stages: the structured light spans both sides of the tooth root surface, the structured light is on one side of the tooth surface, and the structured light spans both sides of the tooth tip surface. (B) The structured light generator includes a laser (B1) and a lens (B2) for generating structured light, or a structured light sensor based on the structured light imaging method. (C) The structured light receiver generally refers to a sensor (CMOS and CCD) that can receive structured light imaging, or a structured light sensor based on the structured light imaging method.

[0047] In the above embodiment, preferably, according to the actual measurement requirements, the specific process of designing a three-dimensional structured light measuring instrument for the involute tooth surface of a gear includes:

[0048] According to the actual measurement requirements for the gear, design the appropriate size of the three-dimensional structured light measuring instrument, process and assemble the physical components to obtain the three-dimensional structured light measuring instrument.

[0049] In the above embodiment, preferably, the specific process of establishing the error system of the digital twin model includes: based on the error information of the three-dimensional structured light measuring instrument, construct a measurement error and uncertainty calculation model based on the digital twin model;

[0050] Based on the digital twin model, establish a sensor signal error model, a static error and a dynamic error model of the measuring instrument.

[0051] As Figure 6 shown, in the above embodiment, preferably, the specific process of using the imaging quality evaluation method based on the camera field of view threshold cut-off strategy to evaluate the imaging of each angle and evaluate to determine the best incident attitude of the structured light for measuring the involute tooth surface includes:

[0052] Based on the camera field of view threshold cut-off strategy, establish an analysis algorithm for the specular reflection and diffuse reflection characteristics of the involute tooth surface to structured light, dynamically obtain and analyze the reflection effect of the involute tooth surface to structured light, quantitatively analyze the intensity and range of the reflected light entering the camera field of view, and evaluate the imaging quality of the images at different incident angles according to the invalid reflection intensity and the proportion of invalid reflection in the whole image;

[0053] Evaluate the best imaging quality of the images at different incident angles, and determine the best incident attitude of the structured light in the three-dimensional structured light measurement structure based on the incident angle corresponding to the best imaging quality.

[0054] According to the optimal incident attitude determination method for measuring the involute tooth surface with line structured light disclosed in the above embodiments, a digital twin model of the line structured light three-dimensional measuring instrument is constructed using digital twin technology. The model includes the geometric errors, assembly errors, sensor installation errors, and inherent errors of the physical components of the actual gear line structured light three-dimensional measuring instrument, realizing a high-fidelity virtual representation of the measuring instrument and having the same measuring function as the actual gear line structured light three-dimensional measuring instrument. Therefore, the measured process of the physical entity to be measured can be simulated through the digital twin model, improving the dynamic monitoring ability of the measuring process.

[0055] By establishing an analysis algorithm for the specular and diffuse reflection characteristics of the involute tooth surface with respect to line structured light, the digital twin model can dynamically obtain and analyze the reflection of the involute tooth surface on the line structured light, quantitatively analyze the intensity and range of the reflected light entering the camera. By establishing an imaging quality evaluation method based on the camera field of view threshold cut-off strategy, it realizes the elimination of invalid data and the evaluation of the incident attitude of the line structured light plane, and gives suggestions on appropriate measuring poses, providing an optimal incident attitude determination method for measuring the involute tooth surface with line structured light and improving the three-dimensional measurement accuracy of gears.

[0056] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for determining the optimal incident attitude of line structured light for measuring an involute tooth surface, characterized in that, it includes: According to the actual measurement requirements, designing a line structured light three-dimensional measurement instrument for the involute tooth surface of a gear; Based on the digital twin technology, constructing a digital twin model corresponding to the line structured light three-dimensional measurement instrument; Measuring the form error, assembly error, sensor installation error and inherent error of the line structured light three-dimensional measurement instrument, as well as the overall error of the measurement system, as error information; According to the error information, establishing an error system of the digital twin model; Constructing an algorithm for analyzing the specular reflection characteristics of the involute tooth surface for line structured light, and mapping the specular reflection effect of the involute tooth surface on the line structured light in the actual measurement process without considering the tooth surface roughness; Constructing an algorithm for analyzing the diffuse reflection characteristics of the involute tooth surface for the structured light plane under the action of roughness, and mapping the diffuse reflection effect of the involute tooth surface on the line structured light in the actual measurement process; Based on the digital twin model under the error system, according to the specular reflection effect and the diffuse reflection effect, simulating and analyzing the reflection characteristics of the involute tooth surface for line structured light at different angles; Using an imaging quality evaluation method based on the camera field of view threshold cut-off strategy to evaluate the imaging of each angle, and evaluating to determine the optimal incident attitude of line structured light for measuring the involute tooth surface; Adjusting the line structured light three-dimensional measurement instrument to the optimal incident attitude.

2. The method for determining the optimal incident attitude of line structured light for measuring an involute tooth surface according to claim 1, characterized in that, The specific process of designing a line structured light three-dimensional measurement instrument for the involute tooth surface of a gear according to the actual measurement requirements includes: According to the actual measurement requirements for the gear, designing the appropriate size of the line structured light three-dimensional measurement instrument, machining and assembling the solid parts to obtain the line structured light three-dimensional measurement instrument.

3. The method for determining the optimal incident attitude of line structured light for measuring an involute tooth surface according to claim 1, characterized in that, The specific process of establishing the error system of the digital twin model includes: According to the error information of the line structured light three-dimensional measurement instrument, constructing a measurement error and uncertainty calculation model based on the digital twin model; Based on the digital twin model, establishing a sensor signal error model, a static error and a dynamic error model of the measurement instrument.

4. The method for determining the optimal incident attitude of line structured light for measuring an involute tooth surface according to claim 1, characterized in that, The specific process of using an imaging quality evaluation method based on the camera field of view threshold cut-off strategy to evaluate the imaging of each angle and evaluating to determine the optimal incident attitude of line structured light for measuring the involute tooth surface includes: Based on the camera field of view threshold cut-off strategy, establishing an algorithm for analyzing the specular reflection and diffuse reflection characteristics of the involute tooth surface for line structured light, dynamically obtaining and analyzing the reflection effect of the involute tooth surface on the line structured light, quantitatively analyzing the intensity and range of the reflected light entering the camera field of view, and evaluating the imaging quality of the images at different incident angles according to the ineffective reflection intensity and the proportion of ineffective reflection in the whole image; Evaluate the best image imaging quality at different incident angles, and determine the best incident attitude of the line structured light in the line structured light three-dimensional measurement structure according to the incident angle corresponding to the best image imaging quality.

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