CN103292722A - Three-dimensional deformation measuring method of non-contact wind power blade whole field - Google Patents

Abstract

The invention provides a three-dimensional deformation measuring method of a non-contact wind power blade whole field. The three-dimensional deformation measuring method of the non-contact wind power blade whole field comprises spraying black and white lusterless paint on the surface of a wind power blade to be measured to form into random scattering spots; performing partition on the whole surface of the wind power blade, calculating three dimensional coordinates of every point of the wind power blade before deformation and calculating three dimensional coordinates of the whole wind power blade under an overall coordination system; and calculating three dimensional displacement of the wind power blade whole field according to differential values of the wind power blade before and after the deformation to obtain a strain value of the wind power blade whole field further. The three-dimensional deformation measuring method of the non-contact wind power blade whole field has the advantages of being whole-field, non-contact and three-dimensional, being capable of obtaining the three dimensional displacement and the strain of the wind power plant whole filed, solving the difficulties and overcoming the disadvantages of contact measuring method and providing technical support for research of wind power blade damage mechanism.

Description

A kind of contactless wind electricity blade whole audience 3 D deformation measuring method

Technical field

The invention belongs to displacement structure videographic measurment field, be specifically related to a kind of contactless wind electricity blade whole audience 3 D deformation measuring method.

Background technology

In recent years, under abundant wind resource condition supported, under the factor such as increasingly mature of the lasting high enterprise of gradually being paid attention to of environmental problem, international oil price and wind power technology drove, global wind-powered electricity generation industry had obtained extraordinary development.Because damage even catastrophic failure may appear in factor affecting such as high wind, electric shock, corrosion, wind-powered electricity generation unit in operational process.In the wind-powered electricity generation unit, wind electricity blade is the parts of most critical, the most expensive, rapid wear, and the rigidity of structure of wind electricity blade and intensity are most important to blower fan one-piece construction load-bearing capacity and reliability, and therefore, the safety guarantee of wind electricity blade has extreme importance.

In order to guarantee the safe operation of wind electricity blade, the research of wind electricity blade damage and failure mechanism is very necessary, and wherein structured testing is indispensable means.Often need measure wind electricity blade at the deformation field of wind action lower surface for wind electricity blade failure mechanism and the research of damage identification, but methods such as traditional foil gauge, extensometer have the strain that range is limited, can only measure single direction, and sensor may destroy difficulties and not enough such as damaging inefficacy because of wind electricity blade.

Summary of the invention

The present invention is directed to above-mentioned the deficiencies in the prior art, a kind of contactless wind electricity blade whole audience 3 D deformation measuring method with advantages such as the whole audience, contactless and three-dimensionals is provided.

The present invention is achieved through the following technical solutions:

A kind of contactless wind electricity blade whole audience 3 D deformation measuring method is characterized in that, may further comprise the steps:

(1) with wind electricity blade to be measured surface spraying black and white sub-gloss varnish, forms speckle point at random;

(2) according to the visual field of industrial digital video camera and the size of wind electricity blade to be measured, whole wind-powered electricity generation blade surface is carried out subregion, and overlap between each subregion, determine the deformation measurement order of each subregion then;

(3) begun by first subregion to be measured, select non-parallel position to set up two industrial digital video cameras above it, observe wind electricity blade respectively from different perspectives;

(4) utilize the binocular stereo vision principle to carry out system calibrating, two industrial digital video cameras are taken the scaling board in this subregion, calculate the inside and outside parameter of two video cameras by the known three-dimensional coordinate of calibration point in the scaling board and the relation of corresponding picture point coordinate;

(5) finish demarcation after, the wind electricity blade before the industrial digital cameras view distortion, institute's speckle image of taking the photograph are as the reference image, with the picture planimetric coordinates substitution collinearity equation of each point, the three-dimensional coordinate of measuring point before obtaining being out of shape;

(6) the industrial digital video camera is taken the wind electricity blade after being out of shape, and speckle image carries out whole audience coupling before and after will being out of shape, and determines that according to maximum correlation coefficient the point of two width of cloth speckle images is to relation;

(7) after coupling finishes, utilize the camera interior and exterior parameter of demarcating in advance, with the picture planimetric coordinates substitution collinearity equation of distortion back each point, obtain being out of shape the three-dimensional coordinate of back measuring point;

(8) according to the method for step (3)-(7), other subregions of wind electricity blade are measured one by one, obtained the three-dimensional coordinate of each subregion distortion front and back each point of wind electricity blade;

(9) three-dimensional coordinate with first subregion is global coordinate system, monumented point by two adjacent subregion laps, determine the mapping relations of three-dimensional system of coordinate and the global coordinate system of other subregion, obtain the three-dimensional coordinate of other subregions under global coordinate system according to mapping relations, can obtain the three-dimensional coordinate of whole wind electricity blade under global coordinate system thus;

(10) by the difference of three-dimensional coordinate before and after the wind electricity blade distortion, be wind electricity blade whole audience three-D displacement;

(11) from displacement field, get a local subarea, utilize least square fitting to obtain displacement function for the displacement of each point in the subarea, with the functional value of this function as the subregion central spot, this function differentiate is obtained strain value;

(12) local subdomain is moved to down a bit, calculate strain value after the wind electricity blade distortion by said process again, thereby so repeat to obtain wind electricity blade whole audience strain value.

Contactless wind electricity blade whole audience 3 D deformation measuring method of the present invention has advantages such as the whole audience, contactless, three-dimensional, can obtain wind electricity blade whole audience three-D displacement and strain, solved the difficulty of contact measurement method and not enough, for the research of wind electricity blade damage and failure mechanism provides technical support.

Embodiment

The invention provides a kind of contactless wind electricity blade whole audience 3 D deformation measuring method, may further comprise the steps:

(1) with wind electricity blade to be measured surface spraying black and white sub-gloss varnish, forms speckle point at random;

(2) according to the visual field of industrial digital video camera and the size of wind electricity blade to be measured, whole wind-powered electricity generation blade surface is carried out subregion, and overlap between each subregion, determine the deformation measurement order of each subregion then; Wherein, the foundation of subregion is exactly to carry out subregion according to the size of the visual field of industrial digital video camera and wind electricity blade to be measured, and measuring sequence is to measure successively along the length direction of wind electricity blade.

(3) begun by first subregion to be measured, select non-parallel position to set up two industrial digital video cameras above it, observe wind electricity blade respectively from different perspectives;

(4) utilize the binocular stereo vision principle to carry out system calibrating, two industrial digital video cameras are taken the scaling board in this subregion, calculate the inside and outside parameter of two video cameras by the known three-dimensional coordinate of calibration point in the scaling board and the relation of corresponding picture point coordinate;

In videographic measurment, for from image, quantitatively extract, geological information and the movable information of measurement space object, must set up the mutual corresponding relation of image point position in the image, and this corresponding relation is determined by camera system imaging model and camera parameters, therefore videographic measurment also needs the inside and outside parameter of video camera in processing image information.But because photocentre, optical axis and the focal length etc. of video camera are not entity physically, be to cannot see impalpablely, they are the parameter of mathematical analysis model more.So before implementing measurement, need determine with calculating by experiment the parameter of photographic measurement system usually, Here it is, and photographic measurement system is demarcated.

The step that photographic measurement system is demarcated is as follows: the OXYZ coordinate is the world coordinate system of object; The oxyz coordinate is the three-dimensional system of coordinate of video camera; X ' y ' coordinate is the two-dimensional image plane coordinate system.Point P is a bit on the space, i.e. the point of required observation, its coordinate not only can be expressed as point (X, the Y under world coordinate system, and can be expressed as point (x, y under camera coordinate system Z),, z), the P point is imaged on picture plane p ' (x ', the y ') point.

Relativeness between the three-dimensional system of coordinate of video camera and the world coordinate system of object can resolve into once around rotation and a translation of true origin, is rotation matrix R and translation matrix T.World coordinate system XYZ is rotated an angle θ around X-axis ₁, obtain new three-dimensional system of coordinate X ₁Y ₁Z ₁With coordinate system X ₁Y ₁Z ₁Around Y ₁Angle θ of axle rotation ₂, obtain new three-dimensional system of coordinate X ₂Y ₂Z ₂With coordinate system X ₂Y ₂Z ₂Around Z ₂Angle θ of axle rotation ₃, obtain new three-dimensional system of coordinate X ₃Y ₃Z ₃With coordinate system X ₃Y ₃Z ₃Move to initial point (X ₀, Y ₀, Z ₀) the place, just can obtain the three-dimensional system of coordinate xyz of last required video camera.So just can obtain the conversion relational expression between two any three-dimensional coordinate systems in space:

$\left[\begin{array}{c}x\\ y\\ z\end{array}\right]=\left[\begin{array}{ccc}{r}_1& r_2& r_3\\ r_4& r_5& r_6\\ r_7& r_8& r_9\end{array}\right]\left[\begin{array}{c}X-X_0\\ Y-Y_0\\ Z-Z_0\end{array}\right]---\left(1\right)$

In the formula:

r ₁=cosθ ₂cosθ ₃-sinθ ₂sinθ ₁sinθ ₃

r ₂=cosθ ₁sinθ ₃

r ₃=sinθ ₂cosθ ₃+cosθ ₂sinθ ₁sinθ ₃

r ₄=-cosθ ₂sinθ ₃-sinθ ₂sinθ ₁cosθ ₃

r ₅=cosθ ₁cosθ ₃

r ₆=-sinθ ₂sinθ ₃+cosθ ₂sinθ ₁cosθ ₃

r ₇=-sinθ ₂cosθ ₁

r ₈=-sinθ ₁

r ₉=cosθ ₂cosθ ₁

Coordinate (the X of projection centre in world coordinate system wherein ₀, Y ₀, Z ₀), rotation matrix R:

$R=\left[\begin{array}{ccc}{r}_1& r_2& r_3\\ r_4& r_5& r_6\\ r_7& r_8& r_9\end{array}\right]$

Translation matrix T: $T=-R\left[\begin{array}{c}{X}_0\\ Y_0\\ Z_0\end{array}\right]---\left(2\right)$

In order to set up geometric relationship intuitively, the xyz of camera coordinates system is moved to the back of photo coordinate system system x ' y ', the effective focal length of lens is f.According to the pinhole imaging system principle, can obtain following relation by the similar triangles relation:

$\left\{\begin{array}{c}{x}^{\′}-x_0=-f\frac{x}{z}\\ y^{\′}-y_0=-f\frac{y}{z}\end{array}\right.---\left(3\right)$

(x in the formula ₀, y ₀) the principal point coordinate, the expression formula of formula (1) is updated in the formula (3), obtain:

$x-x_0=-f\frac{r_1(X-X_0)+r_2(Y-Y_0)+r_3(Z-Z_0)}{r_7(X-X_0)+r_8(Y-Y_0)+r_9(Z-Z_0)}$ （4）

$y-y_0=-f\frac{r_4(X-X_0)+r_5(Y-Y_0)+r_6(Z-Z_0)}{r_7(X-X_0)+r_8(Y-Y_0)+r_9(Z-Z_0)}$

In the superincumbent collinearity equation, for each digital camera, the parameter that needs to demarcate always has 9, has some relevant with the character of video camera itself, is referred to as intrinsic parameter, comprises focus of camera f and principal point coordinate (x ₀, y ₀); Other are then irrelevant with the character of video camera itself, are referred to as outer parameter, comprise θ ₁, θ ₂, θ ₃, X ₀, Y ₀And Z ₀

If known at least 3 topocentric coordinates, and measure corresponding picpointed coordinate, then can list at least 6 equations according to formula (4), solve 6 outer parameters of video camera, thereby carry out system calibrating.

(5) finish demarcation after, the wind electricity blade before the industrial digital cameras view distortion, institute's speckle image of taking the photograph are as the reference image, with the picture planimetric coordinates substitution collinearity equation of each point, the three-dimensional coordinate of measuring point before obtaining being out of shape;

The contrary formula of collinearity equation is:

$X-X_0=(Z-Z_0)\frac{r_{1}x+r_{2}y-r_{3}f}{r_{7}x+r_{8}y-r_{9}f}$ （5）

$Y-Y_0=(Z-Z_0)\frac{r_{4}x+r_{5}y-r_{6}f}{r_{7}x+r_{8}y-r_{9}f}$

Owing to carried out system calibrating, the inside and outside parameter of video camera is known, according to two width of cloth speckle images that two video cameras are taken the photograph, obtains the picture planimetric coordinates of same point in image, is designated as (x ₁, y ₁) and (x ₂, y ₂), with two picture planimetric coordinates substitution formulas (5), and utilize least square method, try to achieve this three-dimensional coordinate in world coordinate system (X, Y, Z).With above-mentioned method, this zone wind electricity blade put one by one calculate, thereby obtain the three-dimensional coordinate of this each point of zone wind electricity blade.

(6) the industrial digital video camera is taken the wind electricity blade after being out of shape, and speckle image carries out whole audience coupling before and after will being out of shape, and determines that according to maximum correlation coefficient the point of two width of cloth speckle images is to relation;

Wherein, the computing formula of maximum correlation coefficient is as follows:

$C=\frac{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}[f(x_i,y_i)-\stackrel{\‾}{f}][g(x_i^{*},y_j^{*})-\stackrel{\‾}{g}]}{\sqrt{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{[f(x_i,y_i)-\stackrel{\‾}{f}]}^2\sqrt{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{m}{\mathrm{\Σ}}}{[g(x_i^{*},y_i^{*})-\stackrel{\‾}{g}]}^2}}}---\left(6\right)$

Here, f (x _i, y _i),

Be respectively the light distribution of distortion front and back speckle field,

Be respectively their arithmetic mean.

(7) after coupling finishes, utilize the camera interior and exterior parameter of demarcating in advance, with the picture planimetric coordinates substitution collinearity equation of distortion back each point, obtain being out of shape the three-dimensional coordinate of back measuring point;

(8) repeat said method, other subregions of wind electricity blade are measured one by one, obtain the three-dimensional coordinate of each subregion distortion front and back each point of wind electricity blade;

(9) three-dimensional coordinate with first subregion is global coordinate system, monumented point by two adjacent subregion laps, determine the mapping relations of three-dimensional system of coordinate and the global coordinate system of other subregion, obtain the three-dimensional coordinate of other subregions under global coordinate system according to mapping relations, can obtain the three-dimensional coordinate of whole wind electricity blade under global coordinate system thus;

(10) by the difference of three-dimensional coordinate before and after the wind electricity blade distortion, be wind electricity blade whole audience three-D displacement;

(11) from displacement field, get a local subarea, utilize least square fitting to obtain displacement function for the displacement of each point in the subarea, with the functional value of this function as the subregion central spot, this function differentiate is obtained strain value;

(12) local subdomain is moved to down a bit, calculate strain value after the wind electricity blade distortion by said process again, thereby so repeat to obtain wind electricity blade whole audience strain value.

Claims (1)

1. a contactless wind electricity blade whole audience 3 D deformation measuring method is characterized in that, may further comprise the steps:

(1) with wind electricity blade to be measured surface spraying black and white sub-gloss varnish, forms speckle point at random;

(2) according to the visual field of industrial digital video camera and the size of wind electricity blade to be measured, whole wind-powered electricity generation blade surface is carried out subregion, and overlap between each subregion, determine the deformation measurement order of each subregion then;

(3) begun by first subregion to be measured, select non-parallel position to set up two industrial digital video cameras above it, observe wind electricity blade respectively from different perspectives;

(4) utilize the binocular stereo vision principle to carry out system calibrating, two industrial digital video cameras are taken the scaling board in this subregion, calculate the inside and outside parameter of two video cameras by the known three-dimensional coordinate of calibration point in the scaling board and the relation of corresponding picture point coordinate;

(5) finish demarcation after, the wind electricity blade before the industrial digital cameras view distortion, institute's speckle image of taking the photograph are as the reference image, with the picture planimetric coordinates substitution collinearity equation of each point, the three-dimensional coordinate of measuring point before obtaining being out of shape;

(6) the industrial digital video camera is taken the wind electricity blade after being out of shape, and speckle image carries out whole audience coupling before and after will being out of shape, and determines that according to maximum correlation coefficient the point of two width of cloth speckle images is to relation;

(7) after coupling finishes, utilize the camera interior and exterior parameter of demarcating in advance, with the picture planimetric coordinates substitution collinearity equation of distortion back each point, obtain being out of shape the three-dimensional coordinate of back measuring point;

(8) according to the method for step (3)-(7), other subregions of wind electricity blade are measured one by one, obtained the three-dimensional coordinate of each subregion distortion front and back each point of wind electricity blade;

(9) three-dimensional coordinate with first subregion is global coordinate system, monumented point by two adjacent subregion laps, determine the mapping relations of three-dimensional system of coordinate and the global coordinate system of other subregion, obtain the three-dimensional coordinate of other subregions under global coordinate system according to mapping relations, can obtain the three-dimensional coordinate of whole wind electricity blade under global coordinate system thus;

(10) by the difference of three-dimensional coordinate before and after the wind electricity blade distortion, be wind electricity blade whole audience three-D displacement;

(11) from displacement field, get a local subarea, utilize least square fitting to obtain displacement function for the displacement of each point in the subarea, with the functional value of this function as the subregion central spot, this function differentiate is obtained strain value;

(12) local subdomain is moved to down a bit, calculate strain value after the wind electricity blade distortion by said process again, thereby so repeat to obtain wind electricity blade whole audience strain value.