A method for on-line measurement of geometric deformation of a mine ventilator blade

Abstract

The application provides a kind of mining ventilator blade geometry deformation on-line measurement method, belong to the technical field of precision measurement of geometric quantity, this method uses 2D laser profile sensor on-line collection blade deformation geometric information, through optimizing the spatial pose and measurement mode of sensor, realize the on-line, high-precision, non-contact measurement of coordinate data, using quartic polynomial least square fitting, curvature analysis and feature recognition, coordinate transformation and least square matching etc. Data-driven method extracts blade deformation characteristic quantity, solves the comprehensive characterization and evaluation problem of mining ventilator blade space deformation state. The application has the characteristics of non-contact, high efficiency, intelligentization, etc., the coordinate measurement accuracy reaches 2 μm level, the curve fitting error is controlled between ±1%, effectively solves the high-precision extraction problem of blade type measurement model, realizes the comprehensive measurement and evaluation of mining ventilator blade geometry deformation, and provides a perfect technical solution for mining ventilator blade deformation measurement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precision measurement of geometric quantities, and particularly to a method for online measurement of geometric deformation of a mine ventilator blade. BACKGROUND

[0002] The blade is an important load-bearing component of the mine ventilator, which is responsible for converting electrical energy into airflow mechanical energy to transport fresh air in the coal mine, and to ensure the safety of production and the health of personnel in the coal mine. In order to optimize the performance of the mine ventilator, the blade must have an accurate shape and a strict spatial pose. However, the blade is prone to geometric deformation under the action of various loads during operation, which will cause the blade to deviate from the theoretical position and affect the efficiency, service life and safety of the mine ventilator. Therefore, blade deformation measurement has important value for improving the operating efficiency of the ventilator and ensuring the safety and stability of the ventilator.

[0003] In the field of aviation, the blade geometry measurement technology has been researched for a long time and has achieved rich research results, which has certain reference significance for the measurement of mine ventilator blades. However, due to the limitations of measurement conditions, geometric characteristics and evaluation contents, the measurement of mine ventilator blades has its inherent uniqueness, and the measurement method of aviation blades is not completely applicable. In the field of coal mines, current researches are mostly focused on non-destructive testing and defect detection of ventilator blades. Due to the limitation of technical level, there are few studies on the geometric deformation measurement method of mine ventilator blades. The deformation measurement of mine ventilator blades is extremely difficult, and it is necessary to solve key problems such as online high-precision measurement of coordinate data, definition and characterization of blade deformation characteristic quantities, and establishment of blade deformation evaluation model. With the increasing attention of the state to safety production, the coal industry has put forward higher requirements for the safety monitoring and risk control of mine ventilators, and the demand for the measurement of mine ventilator blades is becoming more and more intense. Under the new situation, it is particularly necessary to study the online measurement method of mine ventilator blade deformation to lay a technical foundation for performance optimization and safety warning of mine ventilators.

[0004] In summary, the geometric deformation measurement of mine ventilator blades has important theoretical value and practical significance. However, the current researches cannot meet the requirements of efficient detection and safety warning of mine ventilator blades. Therefore, the present application designs a method for online measurement of geometric deformation of mine ventilator blades, which has the characteristics of non-contact, high efficiency and intelligence, and can realize online measurement and evaluation of geometric deformation of mine ventilator blades, thus solving the above problems. SUMMARY

[0005] The present application aims to provide a method for online measurement of geometric deformation of mine ventilator blades to solve the problems raised in the background.

[0006] In order to achieve the above object, the present application provides the following technical scheme: a kind of mine ventilation fan blade geometric deformation online measurement method, comprising the following steps: a kind of mine ventilation fan blade geometric deformation online measurement method, characterized by comprising the following steps:

[0007] S1: using 2D laser profile sensor to collect blade deformation geometry information online;

[0008] S2: extracting blade deformation characteristic quantity based on data-driven method;

[0009] S3: realize the online measurement and analysis of mine ventilation fan blade geometric deformation.

[0010] Preferably, the space deformation state of mine ventilation fan blade is comprehensively represented by using characteristic parameters such as blade profile inclination change amount, blade profile longitudinal displacement and blade profile axial displacement, and the deformation law of mine ventilation fan blade in three-dimensional space is revealed.

[0011] Preferably, the online measurement system based on 2D laser measurement technology is used to extract the geometric information of blade deformation, and the system mainly consists of a triangulation support, a four-degree-of-freedom attitude adjustment mechanism, a 2D laser profile sensor and a measurement and control computer, wherein the 2D laser profile sensor is the core of the measurement system and is responsible for synchronously collecting two-dimensional coordinate data of the measured blade inspection section.

[0012] Preferably, the measurement section at 5mm below the blade tip of 12 o'clock blade is selected as the measurement object, and the establishment of measurement coordinate system o-xyz is completed by optimizing the spatial pose and measurement mode of the sensor.

[0013] Preferably, according to the repeatability error law of 2D laser sensor in full range, the near-field measurement position and 0-650 pixel point section are optimally selected, and the measurement accuracy of the sensor is improved to 2 μm level.

[0014] Preferably, based on the collected original blade profile coordinate data, a quartic polynomial least square fitting algorithm is used to fit and solve the blade profile measurement model, and the fitting error is controlled within ±1%; as shown in formula (1), wherein a0-a4 are model coefficients, which are determined by using least square method. The blade profile measurement model solved by the method has a fitting error controlled within ±1%;

[0015] y(x)=a4x 4 +a3x 3 +a2x 2 +a1x+a0 (1)。

[0016] Preferably, the blade profile registration feature point coordinate set is extracted based on the curvature analysis method. First, the solved blade profile measurement model is differentiated to obtain the first-order and second-order derivatives as shown in formulas (2) and (3). Then, based on the mathematical definition of curvature, the blade profile curvature model is derived using a mathematical analytical method as shown in formula (4). Finally, the curvature model is traversed to search for inflection points and extreme points to extract the blade profile registration feature point coordinate set. The blade profile registration feature point coordinate set consists of blade profile coordinate points that meet the constraints of formulas (5), (6), and (7).

[0017] y′(x)=4a4x 3 +3a3x 2 +2a2x+a1 (2)

[0018] y″(x)=12a4x 2 +6a3x+2a2 (3)

[0019] K(x)=y″(x) / [1+y′(x) 2 ] 3 / 2 (4)

[0020] K(x i )*K(x i+1 )<0 (5)

[0021] K(x i )>K(x i+1 ) and K(x i )>K(x i-1 ) (6)

[0022] K(x i )<K(x i+1 ) and K(x i )<K(x i-1 ) (7).

[0023] Preferably, the blade deformation characteristic quantities such as blade inclination angle change, blade longitudinal displacement, and blade axial displacement are solved based on coordinate transformation and least square matching algorithm to realize comprehensive measurement and evaluation of the geometric deformation of mining fan blades. The specific method is as follows: first, based on the geometric analysis method, the relationship model between the matching coordinates and the measurement coordinates is derived as shown in formula (9); then, models (10) and (11) are established by the least squares theory, and the model matching is converted into a problem of finding extreme values; then, according to Lagrange's theorem, the partial derivatives of the parameters θ, Δx, and Δy are respectively obtained to obtain the equation group (12); finally, the solved characteristic point coordinate set is substituted into formula (12), and the coordinate transformation parameters θ, Δx, and Δy are solved jointly to realize the accurate calculation of the blade deformation characteristic quantities;

[0024]

[0025]

[0026]

[0027]

[0028] Compared with the prior art, the present application has the beneficial effects that the present application solves the comprehensive characterization problem of the geometric deformation of the mine ventilator blade, adopts a 2D laser profile sensor to collect the blade deformation geometric information, realizes online, high-precision and non-contact measurement of coordinate data, through precision optimization, the coordinate measurement precision of this method reaches the 2μm level, the curve fitting error is controlled within ±1%, and the high-precision extraction problem of the blade type measurement model is effectively solved; the blade deformation characteristic quantity is extracted based on the data-driven method, the comprehensive measurement and evaluation of the mine ventilator blade geometric deformation are realized, and a perfect technical solution is provided for the mine ventilator blade deformation measurement.

[0029] Of course, implementing any product of the present application does not necessarily require achieving all the advantages described above at the same time. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed for the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0031] Figure 1 Geometric definition and evaluation model for mine ventilator blade deformation;

[0032] Figure 2 Online measurement system for mine ventilator blade deformation;

[0033] Figure 3 Online measurement process for mine ventilator blade deformation;

[0034] Figure 4 Registration feature point identification process based on curvature analysis;

[0035] Figure 5 Feature point identification result for measuring blade type;

[0036] Figure 6 Blade deformation characteristic quantity solving algorithm based on least square matching;

[0037] Figure 7 Blade deformation evaluation atlas. DETAILED DESCRIPTION

[0038] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0039] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application. Figures 1-7 The present application provides a technical solution: a kind of mine fan blade geometric deformation online measurement method, adopts the characteristic parameter such as leaf type inclination angle variation, leaf type longitudinal displacement, leaf type axial displacement to comprehensively represent and evaluate the spatial deformation state of mine fan blade, the geometric definition and evaluation model of mine fan blade deformation see Figure 1 Leaf type inclination angle variation refers to the inclination angle difference between the measurement leaf type and the standard leaf type, which represents the degree of reverse torsion of the blade; leaf type longitudinal displacement refers to the longitudinal offset of the measurement leaf type and the standard leaf type, which represents the degree of longitudinal deformation of the blade caused by load; leaf type axial displacement refers to the axial offset of the measurement leaf type and the standard leaf type, which represents the degree of axial deformation of the blade caused by load. This representation method is innovatively proposed on the basis of fan blade geometric parameter and mechanical property analysis, and reveals the deformation law of mine fan blade in three-dimensional space.

[0040] As shown in Figure 2 The system mainly consists of a triangulation support, a four-degree-of-freedom attitude adjustment mechanism, a 2D laser profile sensor, a measurement and control computer, etc., wherein the 2D laser profile sensor is the core of the measurement system and is responsible for synchronously collecting two-dimensional coordinate data of the measured blade test section. The sensor projects a line laser onto the measured blade test section, receives the light strip image of the measured shape modulated by the imaging element, obtains the measurement profile through projection transformation according to the obtained image information, realizes two-dimensional coordinate information measurement in the width direction and distance direction of the light curtain, has technical characteristics such as non-contact and high efficiency, and is very suitable for online measurement and analysis of blade deformation.

[0041] Among them, the measurement section at 5 mm below the blade tip of the 12 o'clock blade is selected as the measurement object, the sensor measurement attitude is adjusted through flexible setting of four degrees of freedom of height, front and back, pitch and yaw, and sensor settings such as sampling frequency, light receiving amount, shooting mode and profile extraction algorithm are optimized according to the technical parameters of the sensor until stable, clear and ideal blade measurement profile is collected on the measurement software, and the establishment of the measurement coordinate system o-xyz is completed.

[0042] Based on the repeatability error patterns of 2D laser sensors across their full range, the near-field measurement position and the 0-650 pixel segment were optimized, improving the sensor's measurement accuracy to the 2μm level, thus meeting the precision requirements for blade deformation measurements in mining ventilators. Under the control of measurement software, the high-precision acquisition of the original blade profile coordinate data of the measured cross-section was completed.

[0043] Among them, based on the collected original blade coordinate data P i (x i ,y i ), i = 1, 2, …, n, and a quartic polynomial least squares fitting algorithm is used to fit and solve the blade profile measurement model, as shown in formula (1), where a0 to a4 are model coefficients determined using the least squares method. The blade profile measurement model solved by this method has a fitting error controlled within ±1%.

[0044] y(x)=a4x 4 +a3x 3 +a2x 2 +a1x+a0 (1)

[0045] Among them, Figure 4 As shown in the figure, the leaf profile registration feature point coordinate set is extracted based on the curvature analysis method. The specific method is as follows:

[0046] First, the blade profile measurement model is differentiated to obtain the first-order and second-order derivatives as shown in formulas (2) and (3):

[0047] y′(x)=4a4x 3 +3a3x 2 +2a2x+a1 (2)

[0048] y″(x)=12a4x 2 +6a3x+2a2 (3)

[0049] Then, based on the mathematical definition of curvature, the blade curvature model is derived using a mathematical analytical method:

[0050] K(x)=y″(x) / [1+y′(x) 2 ] 3 / 2 (4)

[0051] Finally, the curvature model is traversed to search for inflection points and extreme points, and the coordinate set of blade profile registration feature points is extracted. The judgment conditions of inflection points, maximum points and minimum points are shown in formulas (5), (6) and (7). The coordinate set of blade profile registration feature points consists of blade profile coordinate points that meet the constraints of formulas (5), (6) and (7). Figure 5 This is the feature point recognition result of the measured blade profile of a certain type of blade. The measured blade profile has four feature points: inflection point A, minimum point B, inflection point C, and maximum point D.

[0052] K(x i )*K(x i+1 )<0 (5)

[0053] K(x i )>K(x i+1 ) and K(x i )>K(x i-1 ) (6)

[0054] K(x i )<K(x i+1 ) and K(x i )<K(x i-1 ) (7)

[0055] Among them, Figure 6 As shown in the figure, the blade deformation characteristic quantity is solved based on the least square matching algorithm. The specific method is:

[0056] According to the least squares matching theory, the blade profile measurement model is rotated and translated, and then least squares matching is performed with the reference model. The solved coordinate transformation parameters θ, Δx, and Δy represent the change in blade profile inclination angle, blade profile axial displacement, and blade profile longitudinal displacement, respectively.

[0057] Assume that the blade profile measurement coordinate is (x i ,y i ), the matching coordinates obtained after transformation are (x′ i ,y′ i ), then the coordinate transformation model is established based on the geometric analysis method as shown in formula (8):

[0058]

[0059] In formula (8), θ is the rotation parameter for converting the measured coordinates to the matching coordinates, and Δx and Δy are the translation parameters for converting the measured coordinate system to the matching coordinates. The relationship model between the matching coordinates and the measured coordinates is derived as shown in formula (9):

[0060]

[0061] Assume the blade profile reference coordinate is (x i ,y″ i ), then the least squares matching model is established as shown in formula (10):

[0062]

[0063] From the least squares theory we know that:

[0064]

[0065] This converts model matching into a problem of finding extreme values, that is, using Equation (11) as the objective function to find the optimal estimated values ​​of the coordinate transformation parameters. According to Lagrange's theorem, the partial derivatives of the parameters θ, Δx, and Δy are taken and set equal to zero, resulting in:

[0066]

[0067] Based on the curvature analysis method, the registration feature points of the measured blade profile and the reference blade profile are identified, and the feature point coordinate set is substituted into formula (12). The coordinate transformation parameters θ, Δx, and Δy are solved jointly to achieve the accurate calculation of the blade deformation feature quantity.

[0068] Among them, such as Figure 7 As shown in the figure, the blade's spatial deformation state is comprehensively characterized and evaluated based on the calculated blade deformation characteristics. The results show that this method effectively extracts various blade deformation characteristic indicators. By analyzing and calculating characteristic parameters such as blade inclination angle change, blade longitudinal displacement, and blade axial displacement, it achieves comprehensive measurement and evaluation of the geometric deformation of mining fan blades. This method is non-contact, highly efficient, and intelligent, providing a comprehensive technical solution for online measurement of mining fan blade geometric deformation.

[0069] A specific application of this embodiment is to use the present invention to measure the deformation state of the blades of a mining ventilator online. First, refer to Figure 1 , the blade inclination angle variation, blade longitudinal displacement, blade axial displacement and other characteristic parameters are used to comprehensively characterize the spatial deformation state of the mining fan blade; further, referring to Figure 2 , the measurement section 5mm below the tip of the blade at 12 o'clock is selected as the measurement object, and the measurement coordinate system o-xyz is established by optimizing the spatial position and measurement mode of the sensor; further, based on the repeatability error law of the 2D laser sensor within the full range, the near-field measurement position and the 0-650 pixel point segment are optimized to improve the sensor measurement accuracy to the 2μm level; further, referring to Figure 2 Under the control of the measurement software, the 2D laser profile sensor is used to collect the two-dimensional coordinate data of the blade inspection section online; further, based on the collected original blade coordinate data, the quartic polynomial least squares fitting algorithm is used to fit and solve the blade measurement model, laying the foundation for the subsequent calculation of blade deformation characteristic quantities. Figure 4 , based on the curvature analysis method, the blade profile registration feature point coordinate set is extracted. The blade profile registration feature point coordinate set consists of blade profile coordinate points that meet the constraints of formulas (5), (6), and (7). Further, referring to Figure 6 , based on the least square matching algorithm, various blade deformation characteristics such as blade inclination angle change, blade longitudinal displacement, blade axial displacement, etc. are solved; further, referring to Figure 7According to the blade deformation characteristic quantity solved, the spatial deformation state of the blade is comprehensively represented and evaluated. Figure 3 The work flow of the application is shown in the figure, and the application has the characteristics of non-contact, high efficiency and intelligence, and provides a perfect technical solution for the online measurement of the geometric deformation of the mine fan blade.

[0070] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0071] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments described. Obviously, many modifications and changes can be made according to the content of the present specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited only by the claims and their full scope and equivalents.

Claims

1. A method for online measurement of geometrical deformation of a mine ventilation fan blade, characterized by, It comprises the following steps: S1, using 2D laser profile sensor to collect blade deformation geometry information online; S2, extracting blade deformation characteristic quantity based on data-driven method; S3, realizing online measurement and analysis of mine ventilator blade geometric deformation; The feature parameters are used to comprehensively represent the spatial deformation state of the mine ventilator blade, and the deformation law of the mine ventilator blade in three-dimensional space is revealed. The feature parameters include the leaf type inclination change, the leaf type longitudinal displacement, and the leaf type axial displacement. The online measurement system based on 2D laser measurement technology is used to extract the geometric information of the blade deformation. The system mainly comprises a triangulation support, a four-degree-of-freedom attitude adjustment mechanism, a 2D laser profile sensor, and a measurement and control computer. The 2D laser profile sensor is the core of the measurement system and is responsible for synchronously collecting the two-dimensional coordinate data of the measured blade inspection profile. Based on the collected original blade profile coordinate data, a quartic polynomial least squares fitting algorithm is used to fit and solve the blade profile measurement model, and the fitting error is controlled within ±1%, as shown in formula (1). Wherein a0-a4 are model coefficients, which are determined by the least squares method. The solved blade profile measurement model has a fitting error controlled within ±1%. y(x) = a4x 4 + a3x 3 + a2x 2 + a1x + a0 (1) Based on the curvature analysis method, the coordinates of the registration feature points are extracted. First, the first and second derivatives of the solved blade profile measurement model are obtained as shown in formulas (2) and (3). Then, according to the mathematical definition of curvature, the blade curvature model is derived by mathematical analysis as shown in formula (4). Finally, the curvature model is traversed to search for inflection points and extreme points, and the coordinates of the registration feature points are extracted. The coordinates of the registration feature points are composed of blade coordinate points that satisfy the constraints of formulas (5), (6), and (7). y'(x) = 4a4x 3 + 3a3x 2 + 2a2x + a1 (2) y"(x) = 12a4x 2 + 6a3x + 2a2 (3) K(x) = y"(x) / [1 + y'(x) 2 ] 3 / 2 (4) K(x i )*K(x i+1 ) < 0 (5) K(x i ) > K(x i+1 ) and K(x i ) > K(x i-1 ) (6) K(x i ) < K(x i+1 ) and K(x i ) < K(x i-1 ) (7).

2. A method for on-line measurement of geometrical deformations of a mine ventilator blade as claimed in claim 1, characterized in that, The measurement profile at 5mm below the 12 o'clock blade tip is selected as the measurement object. By optimizing the spatial pose and measurement mode of the sensor, the measurement coordinate system o-xyz is established.

3. A method for on-line measurement of geometrical deformations of a mine ventilator blade according to claim 1, characterized in that, According to the repeatability error law of the 2D laser sensor in the full range, the near-field measurement position and the 0-650 pixel point section are optimally selected to improve the sensor measurement accuracy to the order of 2μm.

4. A method for on-line measurement of geometrical deformations of a mine ventilator blade according to claim 1, characterized in that, Based on the coordinate transformation and least squares matching algorithm, the blade deformation characteristic quantity is solved, including the leaf type inclination change, the leaf type longitudinal displacement, and the leaf type axial displacement. The comprehensive measurement and evaluation of the mine ventilator blade geometric deformation are realized. The specific method is as follows. First, the relationship model between the matching coordinates and the measurement coordinates is derived based on the geometric analysis method as shown in formula (9). Then, the models (10) and (11) are established by the least squares method theory. The model matching is converted into the problem of solving the extreme value. Then, according to the Lagrange theorem, the partial derivatives of the parameters θ, Δx, and Δy are obtained, and the equation group (12) is obtained. Finally, the solved feature point coordinate set is substituted into formula (12), and the coordinate transformation parameters θ, Δx, and Δy are solved to realize the accurate calculation of the blade deformation characteristic quantity. The coordinate transformation parameters θ, Δx and Δy respectively represent a blade profile inclination change amount, a blade profile axial displacement and a blade profile longitudinal displacement; a blade profile measurement coordinate is (x i ,y i ), the matching coordinate obtained after transformation is (x′ i ,y′ i ), and a blade profile reference coordinate is (x″ i ,y″ i ); θ is a rotation parameter for converting the measurement coordinate into the matching coordinate, and Δx and Δy are translation parameters for converting the measurement coordinate system into the matching coordinate.

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