CN103759669A - Monocular vision measuring method for large parts - Google Patents

Abstract

The invention relates to a monocular vision measuring method for large parts, and belongs to the technical field of measuring. According to the monocular vision measuring method for the large parts, planning analysis is carried out on the optimal point of sight of a part to be tested by adopting a video camera shifting method, limitation of one-time measuring of the video camera is overcome, and the measuring range is enlarged. After the video camera finishes measurement in an effective field of view, the video camera is moved to another position, the fact that the pose of a shifting ball does not change is guaranteed, a measuring bar is rotated to enable the face, posted with a marking point, of the measuring bar to directly face the video camera, the rotating angle of the measuring bar is recorded, the mutual relation before the shifting and after the shifting can be obtained through the shifting ball and marking holes in the shifting ball, space splicing can be carried out on multiple sets of coordinate values through the mutual relation before the shifting and after the shifting, and reconstitution on the three-dimensional shape of a large part by using an existing instrument is achieved.

Description

A kind of monocular vision measuring method of heavy parts

Technical field

The monocular vision measuring method that the present invention relates to a kind of heavy parts, belongs to field of measuring technique.

Background technology

Large-sized curved surface is widely used at aspects such as auto industry, boats and ships and spacecraft profiles in recent years, development need along with modern processing and manufacturing and production operation, the measurement of heavy parts three-dimensional geometry size has become the shoring of foundation technology of modern reverse-engineering and Product Digitalization Design and manufacture, and increasing assembling, quality control, detect online, the also three-dimensional measurement of heavy parts in the urgent need to address of the fields such as tool locating of industrial products.

Along with being gradually improved and the continuous progress of the technology such as image processing, pattern-recognition of computer technology, electronics, optical technology, computer vision measurement technology is rapidly developed, and becomes gradually the topmost measurement means of heavy parts surface three dimension information.At present the heavy parts measuring technique based on monocular vision mainly contains: geometric similarity method is measured, geometric constraints method is measured, structured light method is measured, geometrical optics approach is measured and auxiliary target mapping amount, wherein only has the measurement that auxiliary target mapping amount can the invisible point in implementation space.

On target, be generally designed with the mark with distinct characteristic and produce monumented point, whether luminous according to monumented point, target can be divided into gauge without light source target and have light source target two classes, wherein gauge without light source target is the special pattern generating monumented point utilizing on target, be generally and obtain desirable monumented point image, also need to use specific light source to irradiate target, this kind of target is affected by environment larger; There is light source target to utilize luminophor, for example LED produces monumented point, tradition has light source target to determine light point area by two-value method, utilize gravity model appoach or ellipse fitting method to extract monumented point center, binary conversion treatment and the imaging of monumented point different angles due to image, the optical spot centre proposing by gravity model appoach or ellipse fitting method, not corresponding to same point in space, reduces measuring accuracy.

The patent No. is CN200910058832, a kind of optical three-coordinate measuring method based on phase target is provided, the measuring principle of this measuring method is that video camera obtains the characteristic image in characteristic image screen in phase target, by phase shift fringe analysis method or Fourier fringe analysis method, calculate PHASE DISTRIBUTION, set up the corresponding relation between each point and camera pixel in target electronic display, and then the three dimensional space coordinate of definite target gauge head contact, by travel(l)ing phase target, multimetering is carried out in testee surface, to calculate thing 3 d shape, when this phase target is used for optical three-dimensional measurement, with have the auxiliary target of 3 above gauge points and compare, due to increasing in a large number of unique point quantity, and the unique point based on phase calculation is accurately extracted, make its measurement result more accurate and reliable, but because the one-shot measurement visual field of video camera is limited, while having determined to measure for some large-scale workpiece, video camera and tested part keep a relative position can not tested point on all parts be measured complete, this has limited the scope and the application of this system for heavy parts of measuring greatly.

Summary of the invention

The monocular vision measuring method that the object of this invention is to provide a kind of heavy parts, cannot measure complete problem by all tested points in heavy parts to solve limited causing of measurement range in current monocular vision measuring process.

The present invention provides a kind of monocular vision of heavy parts measuring method for solving the problems of the technologies described above, this measuring method is put on by auxiliary target turns the measurement of fighting in different parts that station ball is realized video camera, the auxiliary target using comprises a measuring staff, measuring staff top is rotatably equipped with station ball, this turns station and is evenly laid with index aperture on ball surface, on this measuring staff, be also installed with the measuring stick that can rotate with measuring staff, on a face of this measuring stick, be provided with monumented point, described in turn ball below, station and be fixedly installed the platform that turns that is carved with angle value;

When described measuring method is measured, the one side that auxiliary target is put on be provided with monumented point is over against video camera, by video camera, obtain the characteristic image information of target monumented point, after measuring in video camera Yi Ge apparent field, mobile camera is to another position, assurance turns station ball pose and does not change, rotate measuring staff makes the one side of posting monumented point over against video camera simultaneously, and record the anglec of rotation of measuring staff, simultaneously by turning station ball and turning each index aperture on the ball of station, obtain turning and stand afterwards and turn the mutual relationship before station, by the mutual relationship between them, some groups of coordinate figures that obtain are carried out to space splicing to realize the reconstruct to heavy parts pattern.

Described measuring method comprises the following steps:

1) video camera vision measurement system is demarcated, determined camera inner parameter and system structure parameter, auxiliary target is demarcated, determine and under auxiliary target coordinate system, turn each monumented point center and gauge head coordinate on Zhan Qiugekong center, survey rod;

2) one side of auxiliary target mapping probe being posted to monumented point, over against video camera, is obtained the characteristic image information of target monumented point by video camera;

3) the characteristic image information of the target monumented point collecting is carried out to image processing and obtain each monumented point center pixel coordinate;

4) according to pin-hole imaging principle, set up systematic survey model, the pixel coordinate at monumented point center is carried out to coordinate conversion and obtain the coordinate figure of survey mark dot center in world coordinate system, calculate auxiliary target coordinate system to rotation and the translation matrix of world coordinate system, according to calculated rotation and translation matrix and the gauge head center coordinate under auxiliary target coordinate system, calculate the world coordinates value at gauge head center;

5) after measuring in video camera Yi Ge apparent field, mobile camera, to another position, starts the measurement of another location, until all measurement of curved surface of heavy parts are complete;

6) according to the mutual relationship that turns position in coordinate figure in auxiliary target coordinate system of each uniquely identified hole on the ball of station and image coordinates system, the D coordinates value of respectively organizing obtaining is carried out to space splicing, finally realize the reconstruct to heavy parts object dimensional pattern.

Described step 2) when measuring, surveying excellent axis is positioned at and turns platform 0 scale place, and auxiliary target mapping probe posts monumented point one side over against video camera, when the rigid body measuring head of putting on when auxiliary target contacts with curved surface tested point is vertical, switch synchro control video camera on gauge head obtains the characteristic image information of target monumented point, and image pick-up card gathers image.

In described step 4), auxiliary target coordinate system to the transformation for mula of world coordinate system is:

$\left(\begin{array}{c}{x}_w\\ y_{\mathrm{<figure-callout\; id="1"\; label="w\; z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">w</figure-callout>}}& \\ z_w{}_{}\\ 1\end{array}\right)=\left(\begin{array}{cc}{R}^{\&prime;}& t^{\&prime;}\\ 0^t& 1\end{array}\right)\left(\begin{array}{c}{x}_f\\ y_{\mathrm{<figure-callout\; id="1"\; label="f\; z\; f"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">f</figure-callout>}}& \\ z_f{}_{}\\ 1\end{array}\right)$

Wherein, (x _f, y _f, z _f, 1) ^t(x _w, y _w, z _w, 1) ^trespectively the coordinate of P in auxiliary target coordinate system and world coordinate system; R ' is the rotation matrix to world coordinate system by auxiliary target coordinate system, and t ' is the translation vector to world coordinate system by auxiliary target coordinate system.

After described step 5) is measured in video camera Yi Ge apparent field, mobile camera is to another position, assurance turns station ball position and does not change and rotate auxiliary target target simultaneously and survey rod and make the one side of posting monumented point over against video camera, starts the measurement of another location, realizes turning station and measuring.

Described step 1) is carried out timing signal to video camera vision measurement system and is adopted auxiliary target to complete the demarcation of video camera, and video camera and auxiliary target are fixed in a distance, opens ccd video camera power supply; Within the scope of camera field of view, choose the summit of gauge block as calibration point, piece image is taken in position of every movement, and the two-dimensional image information of the monumented point of acquisition is transmitted and be saved in computing machine by network data line; The monumented point image coordinate of all positions of utilize extracting and corresponding the known world coordinate thereof, bring in pinhole imaging system Measuring System Models, and then complete the solving of camera interior and exterior parameter, and be saved in systems parameters document, in order to measuring phases, calls.

The invention has the beneficial effects as follows: the present invention carries out planning application by the method that adopts video camera to turn station to the best view of device under test, overcome the finiteness of video camera one-shot measurement, expanded the scope of measuring, after measuring in video camera Yi Ge apparent field, mobile camera is to another position, assurance turns station ball pose and does not change, rotate measuring staff makes the one side of posting monumented point over against video camera simultaneously, and record the anglec of rotation of measuring staff, simultaneously by turning station ball and turning each index aperture on the ball of station, can obtain turning and stand afterwards and turn the mutual relationship before station, by the mutual relationship between them, some groups of coordinate figures can be carried out to space splicing, the reconstruct of realization to heavy parts three-dimensional appearance.

Accompanying drawing explanation

Fig. 1 is the structural drawing of monocular vision measuring system used in the present invention;

Fig. 2 is the structural representation of subsidiary target used in the present invention;

Fig. 3 is the coordinate conversion schematic diagram of monocular vision measuring method of the present invention;

Fig. 4 is the schematic diagram that is related to of camera coordinate system and pixel coordinate system;

Fig. 5 is auxiliary coordinates schematic diagram;

Fig. 6 is subsidiary target system calibrating model schematic diagram used in the present invention.

Embodiment

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is further described.

The embodiment of the monocular vision measuring method of a kind of heavy parts of the present invention

The monocular vision measuring method of heavy parts of the present invention accurately extracts monumented point centre coordinate by monumented point is rationally set, the station ball that turns of putting on by auxiliary target is realized the measurement of fighting in different parts of video camera, expanded the scope of measuring, realized heavy parts measured to requirement fast, cheaply.Measuring system used in the present invention as shown in Figure 1, comprise video camera 6, computing machine and subsidiary target, wherein subsidiary target as shown in Figure 2, comprise measuring staff 1, on measuring staff 1, be rotatably equipped with station ball 2, turn ball 2 belows, station and be installed with and turn platform 3, on measuring staff 1, being also installed with can be with the survey rod 4 of measuring staff 1 rotation, on a face of survey rod 3, be provided with monumented point, measuring staff 1 below is provided with gauge head 5.

Turning station ball 2 is a spheroid, and turning station ball 2 is a spheroid, on its outside surface, according to certain angle, is laid with index aperture uniformly in the intersection location of warp and parallel, and index aperture is the cylindrical hole G lower than spherome surface ₁, G ₂..., G _nthe axis of each index aperture and the centre of sphere intersect, in each index aperture, paste respectively the different circular thin subsides of colored light echo reflection of shades of colour, the position of each index aperture in auxiliary target determined by colour code is unique, walk around and be carved with the angle of 360 degree uniform encodings on platform 3, the angle of the rotation of measuring staff while fighting in different parts measurement for showing, surveying rod 3 is an ater rectangular parallelepiped, is provided with 16 circular light echos reflection auxiliary sign point N that dimension information is known on one of them surface ₁, N ₂..., N ₁₆with 4 measurement monumented point P ₁, P ₂, P ₃, P ₄, the distribution of being rectangle of every 4 auxiliary sign points, respectively in rectangular 4 summits, 16 auxiliary sign points are divided into 4 rectangular profile regions, 4 measurements with monumented point respectively on above-mentioned 4 cornerwise intersection points of rectangular region, each monumented point is provided with a kind of glass particle of high index of refraction, reflection strength is high, survey clavate with black and become sharp contrast, be easy to be separated with background light source, to form clear and outstanding bianry image, it is reference position with turning the tangent place of platform that survey rod has the one side of monumented point, during measurement, the excellent both sides of hand-held survey make the one side of posting monumented point over against video camera 6.

Gauge head 4 has good rigidity and sphericity, can detect flexibly the point on various surfaces externally and internallies, on gauge head 4, trigger switch is installed, to facilitate the sampling of controlling measured point, generally select sphericity high have that high-hardness ceramic material makes industrial ruby, during measurement, gauge head is tightly close to measured point, guarantee the stability of target in image acquisition, the length of measuring staff 5 can regulate according to tested part, for meeting, measure rigidity requirement, measuring staff length is more short better, increase measuring staff length and can reduce measuring accuracy, but for some difficult position or blind spot of surveying, measuring staff length can regulate according to actual measurement situation, be particularly suitable for aircraft wing or fuselage, automobile chassis or vehicle body, the measurement of the objects such as workshop platform, the length that considers measuring staff should be selected 50-110mm.

The measuring process of the monocular vision measuring method of the above-mentioned subsidiary target of use of the present invention is as follows:

1. model coordinate system, as shown in Figure 3, the focus of video camera of take is set up camera coordinate system O as initial point _cx _cy _cz _c, using the optical axis of video camera as Z _caxle, f is the focal length of video camera, it is fixed on video camera, follows right-hand rule, and camera coordinates is used as to world coordinate system, using camera optical axis with as the focus of plane, as true origin O, set up photo coordinate system OXY, pixel coordinate is OUV, and as shown in Figure 4, its true origin is in the upper left corner of video camera and photo coordinate system image, take pixel as unit, take that to assist the fight in different parts centre of sphere of ball of target be initial point; As shown in Figure 5, set up auxiliary coordinates O _fx _fy _fz _f, turning the center in the hole coordinate under auxiliary coordinates on ball surface, station is x _fG, y _fG, z _fG, the coordinate of survey mark dot center under auxiliary coordinates is

(j=1,2,3,4), the coordinate of gauge head center under auxiliary coordinates is (x _fN, y _fN, z _fN); P is any point in space, and p is the imaging point of P in picture plane.From space, any point P projects to p in camera plane, and in conjunction with rigid body translation knowledge, its conversion process is as follows:

World coordinate system is with respect to the transformation for mula of camera coordinate system:

$\left(\begin{array}{c}{x}_c\\ y_{\mathrm{<figure-callout\; id="1"\; label="c\; z\; c"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">c</figure-callout>}}& \\ z_c{}_{}\\ 1\end{array}\right)=\left(\begin{array}{cc}R& t\\ 0^t& 1\end{array}\right)\left(\begin{array}{c}{x}_w\\ y_{\mathrm{<figure-callout\; id="1"\; label="w\; z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">w</figure-callout>}}& \\ z_w{}_{}\\ 1\end{array}\right)$

(x _c, y _c, z _c, 1) ^t(x _w, y _w, z _w, 1) ^trespectively the coordinate of P in camera coordinate system and world coordinate system; R is tied to the rotation matrix of camera coordinate system by world coordinates, t is tied to the translation vector of camera coordinate system by world coordinates.Camera coordinates is tied to the transformation for mula of video camera photo coordinate system:

$z_c\left(\begin{array}{c}x\\ \mathrm{<figure-callout\; id="1"\; label="y"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">y</figure-callout>}\\ 1\end{array}\right)=\left(\begin{array}{cccc}\mathrm{<figure-callout\; id="0"\; label="f"\; filenames="HDA0000453144090000021.png"\; state="\{\{state\}\}">f</figure-callout>}& 0& 0& 0\\ 0& \mathrm{<figure-callout\; id="0"\; label="f"\; filenames="HDA0000453144090000021.png"\; state="\{\{state\}\}">f</figure-callout>}& 0& 0\\ 0& 0& 1& 0\end{array}\right)\left(\begin{array}{c}{x}_c\\ y_{\mathrm{<figure-callout\; id="1"\; label="c\; z\; c"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">c</figure-callout>}}& \\ z_c{}_{}\\ 1\end{array}\right)$

Wherein, (x, y, 1) ^tthat p is at the coordinate of video camera photo coordinate system.

The transformation for mula that camera plane coordinate is tied to pixel coordinate system is:

$\left(\begin{array}{c}u\\ v\\ 1\end{array}\right)=\left(\begin{array}{ccc}1/\mathrm{dx}& 0& u_0\\ 0& 1/\mathrm{dy}& v_0\\ 0& 0& 1\end{array}\right)\left(\begin{array}{c}x\\ \mathrm{<figure-callout\; id="1"\; label="y"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">y</figure-callout>}\\ 1\end{array}\right)$

Wherein, (u, v, 1) ^tthe coordinate of p under pixel coordinate system; d _x, d _yrespectively the physical size of each pixel in X-axis and Y direction in pixel coordinate system, (u ₀, v ₀) be the initial point O of the physical coordinates system coordinate in pixel coordinate system.In sum, the coordinate (x of 1, space P in world coordinate system _w, y _w, z _w) as follows with the relation of the coordinate (u, v) of its subpoint p in picture plane in pixel coordinate system:

$z_{\mathrm{<figure-callout\; id="1"\; label="c\; u\; v"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">c</figure-callout>}}\left(\begin{array}{c}u\\ v\end{array}\right)\left(\begin{array}{c}\\ 1\end{array}\right)=\left(\begin{array}{ccc}1/\mathrm{dx}& 0& u_0\\ 0& 1/\mathrm{dy}& v_0\\ 0& 0& 1\end{array}\right)\left(\begin{array}{cccc}\mathrm{<figure-callout\; id="0"\; label="f"\; filenames="HDA0000453144090000021.png"\; state="\{\{state\}\}">f</figure-callout>}& 0& 0& 0\\ 0& \mathrm{<figure-callout\; id="0"\; label="f"\; filenames="HDA0000453144090000021.png"\; state="\{\{state\}\}">f</figure-callout>}& 0& 0\\ 0& 0& 1& 0\end{array}\right)\left(\begin{array}{cc}R& t\\ 0^t& 1\end{array}\right)\left(\begin{array}{c}{x}_w\\ y_{\mathrm{<figure-callout\; id="1"\; label="w\; z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">w</figure-callout>}}& \\ z_w{}_{}\\ 1\end{array}\right)$

$=\left(\begin{array}{cccc}{f}_x& 0& u_0& 0\\ 0& {\mathrm{<figure-callout\; id="0"\; label="f\; y\; v"\; filenames="HDA0000453144090000021.png"\; state="\{\{state\}\}">f</figure-callout>}}_y& v_{}{}_0& 0\\ 0& 0& 1& 0\end{array}\right)\left(\begin{array}{cc}R& t\\ 0^t& 1\end{array}\right)\left(\begin{array}{c}{x}_w\\ y_{\mathrm{<figure-callout\; id="1"\; label="w\; z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">w</figure-callout>}}& \\ z_w{}_{}\\ 1\end{array}\right)=\left(\begin{array}{ccc}{f}_x& 0& u_0\\ 0& {\mathrm{<figure-callout\; id="0"\; label="f\; y\; v"\; filenames="HDA0000453144090000021.png"\; state="\{\{state\}\}">f</figure-callout>}}_y& v_{}{}_0\\ 0& 0& 1\end{array}\right)\left(\begin{array}{cc}R& t\\ 0^t& 1\end{array}\right)\left(\begin{array}{c}{x}_w\\ y_{\mathrm{<figure-callout\; id="1"\; label="w\; z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">w</figure-callout>}}& \\ z_w{}_{}\\ 1\end{array}\right)$

$=M_1{M}_2\left(\begin{array}{c}{x}_w\\ y_{\mathrm{<figure-callout\; id="1"\; label="w\; z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">w</figure-callout>}}& \\ z_w{}_{}\\ 1\end{array}\right)=M\left(\begin{array}{c}{x}_w\\ y_{\mathrm{<figure-callout\; id="1"\; label="w\; z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">w</figure-callout>}}& \\ z_w{}_{}\\ 1\end{array}\right)$

Wherein, matrix M ₁by f _x, f _y, u ₀, v ₀determine f _x, f _yrepresent respectively the projector distance of focal distance f in image X-axis and Y direction, the inner parameter of these parameters and camera is relevant, so M1 is called to the internal reference matrix of video camera, M2 has reflected that world coordinates is tied to the conversion process of camera coordinate system, irrelevant with the intrinsic parameter of video camera, so M2 is called the outer parameter matrix of video camera.

Auxiliary target coordinate system is to the transformation for mula of world coordinate system:

$\left(\begin{array}{c}{x}_w\\ y_{\mathrm{<figure-callout\; id="1"\; label="w\; z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">w</figure-callout>}}& \\ z_w{}_{}\\ 1\end{array}\right)=\left(\begin{array}{cc}{R}^{\&prime;}& t^{\&prime;}\\ 0^t& 1\end{array}\right)\left(\begin{array}{c}{x}_f\\ y_{\mathrm{<figure-callout\; id="1"\; label="f\; z\; f"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">f</figure-callout>}}& \\ z_f{}_{}\\ 1\end{array}\right)$

Wherein, (x _f, y _f, z _f, 1) ^t(x _w, y _w, z _w, 1) ^trespectively the coordinate of P in auxiliary target coordinate system and world coordinate system; R ' is the rotation matrix to world coordinate system by auxiliary target coordinate system, and t ' is the translation vector to world coordinate system by auxiliary target coordinate system.

2. system calibrating

Camera calibration, in monocular vision, camera calibration parameter is divided into inner parameter and external parameter, inner parameter has been determined geometry and the optical signature of video camera inside, the variation with camera position does not change, comprise video camera effective focal length and attitude, when camera position changes, need to again demarcate.The scaling method that the present invention adopts is to utilize auxiliary target to complete the demarcation of video camera, timing signal fixes video camera and auxiliary target in a distance, open ccd video camera power supply, within the scope of camera field of view, as shown in Figure 6, choose the summit of gauge block as calibration point, a sub-picture is taken in position of every movement, the two-dimensional image information of the monumented point of acquisition is transmitted and is saved in computing machine by network data line, utilize to extract monumented point image coordinate and the corresponding the known world coordinate thereof of all positions, bring in pinhole imaging system Measuring System Models, and then complete solving camera interior and exterior parameter, and be saved in systems parameters document, in order to measuring phases, call, concrete computational engineering is as follows:

The present invention adopts linear model to calculate, and is established to summit p _iworld coordinate system coordinate (the x of i=(1,2,3,4,5,6,7) _wi, y _wi, z _wi) with the relation of its imaging point p coordinate (u, v) in image pixel coordinate system.

$z_{\mathrm{ci}}\left(\begin{array}{c}{u}_i\\ v_i\\ 1\end{array}\right)=M\left(\begin{array}{c}{x}_{\mathrm{wi}}\\ y_{\mathrm{<figure-callout\; id="1"\; label="wi\; z\; wi"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">wi</figure-callout>}}& \\ z_{\mathrm{wi}}{}_{}\\ 1\end{array}\right)=\left(\begin{array}{cccc}{m}_{11}& m_{12}& m_{13}& m_{14}\\ m_{21}& m_{22}& m_{23}& m_{24}\\ m_{31}& m_{32}& m_{33}& m_{34}\end{array}\right)\left(\begin{array}{c}{x}_{\mathrm{wi}}\\ y_{\mathrm{wi}}\\ z_{\mathrm{wi}}\\ 1\end{array}\right)$

M wherein _ijfor the capable j column element of i of transform matrix M, above formula can be write as following system of equations:

$\left\{\begin{array}{c}{z}_{\mathrm{ci}}{u}_i=m_{11}{x}_{\mathrm{wi}}+m_{12}{y}_{\mathrm{wi}}+m_{13}{z}_{\mathrm{wi}}+m_{14}\\ z_{\mathrm{ci}}{v}_i=m_{21}{x}_{\mathrm{wi}}+m_{22}{y}_{\mathrm{wi}}+m_{23}{z}_{\mathrm{wi}}+m_{24}\\ z_{\mathrm{ci}}=m_{31}{x}_{\mathrm{wi}}+m_{32}{y}_{\mathrm{wi}}+m_{33}{z}_{\mathrm{wi}}+m_{34}\end{array}\right.$

Abbreviation, cancellation z will be carried out in above formula _ci, can release two unknown numbers is m _ijlinear equation:

$\left\{\begin{array}{c}{x}_{\mathrm{wi}}{m}_{11}+y_{\mathrm{wi}}{m}_{12}+z_{\mathrm{wi}}{m}_{13}+m_{14}-u_i{x}_{\mathrm{wi}}{m}_{31}-u_i{y}_{\mathrm{wi}}{m}_{32}-u_i{z}_{\mathrm{wi}}{m}_{33}=u_i{m}_{34}\\ x_{\mathrm{wi}}{m}_{21}+y_{\mathrm{wi}}{m}_{22}+z_{\mathrm{wi}}{m}_{23}+m_{24}-v_i{x}_{\mathrm{wi}}{m}_{31}-v_i{y}_{\mathrm{wi}}{m}_{32}-v_i{z}_{\mathrm{wi}}{m}_{33}=v_i{m}_{34}\end{array}\right.$

World coordinates substitution above formula by the calibration point of n on target, can obtain 2n linear equation, as follows by matrix representation:

$\left[\begin{array}{ccccccccccc}{x}_{w1}& y_{w1}& {\mathrm{<figure-callout\; id="1"\; label="z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">z</figure-callout>}}_w& 1& 0& 0& 0& 0& -u_1{x}_{w1}& -u_1{y}_{w1}& -u_1{\mathrm{<figure-callout\; id="1"\; label="z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">z</figure-callout>}}_w\\ 0& 0& 0& 0& x_{w1}& y_{w1}& {\mathrm{<figure-callout\; id="1"\; label="z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">z</figure-callout>}}_w& 1& -v_1{x}_{w1}& -v_1{y}_{w1}& -u_1{\mathrm{<figure-callout\; id="1"\; label="z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">z</figure-callout>}}_w\\ .& .& .& .& .& .& .& .& .& .& .\\ .& .& .& .& .& .& .& .& .& .& .\\ .& .& .& .& .& .& .& .& .& .& .\\ x_{\mathrm{wn}}& y_{\mathrm{wn}}& {\mathrm{<figure-callout\; id="1"\; label="z\; wn"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">z</figure-callout>}}_{\mathrm{wn}}& 1& 0& 0& 0& 0& -u_n{x}_{\mathrm{wn}}& -u_n{y}_{\mathrm{wn}}& -u_{\mathrm{<figure-callout\; id="0"\; label="n\; z\; wn"\; filenames="HDA0000453144090000021.png"\; state="\{\{state\}\}">n</figure-callout>}}{z}_{\mathrm{wn}}{}_{}\\ 0& 0& 0& 0& x_{\mathrm{wn}}& y_{\mathrm{wn}}& z_{\mathrm{wn}}& 1& -v_n{x}_{\mathrm{wn}}& -v_n{y}_{\mathrm{wn}}& -v_n{z}_{\mathrm{wn}}\end{array}\right].$

${\left[\begin{array}{ccccccccccc}{m}_{11}& m_{12}& m_{13}& m_{14}& m_{21}& m_{22}& m_{23}& m_{24}& m_{31}& m_{32}& m_{33}\end{array}\right]}^T$

$={\left[\begin{array}{ccccc}{u}_1{m}_{34}& v_1{m}_{34}& ...& u_n{m}_{34}& v_1{m}_{34}\end{array}\right]}^T$

Suppose m ₃₄be 1, formula above formula can be write as:

Km＝U

Wherein, 2n * 11 matrix that K is, m is 11 dimensional vectors that need to obtain; U is 2n dimensional vector.

Known 2n > 11, available least square method is obtained the solution of matrix M

m＝(K ^TK) ^-1K ^TU

3. image acquisition

The image transmitting that image pick-up card is gathered is to computing machine, through image, process and obtain each auxiliary sign dot profile pixel coordinate, first adopt least square ellipse matching to obtain the pixel coordinate value of 16Ge auxiliary sign dot center, every 4 auxiliary sign dot center can construct quadrilateral, utilize quadrilateral diagonal line intersection point to obtain 4 pixel coordinate value (u of survey mark dot center _i, v _i) (i=1,2,3,4).

4. tested point calculating coordinate, the imaging model of video camera is based on pin-hole imaging principle, C ₁, C ₂, C ₃, C ₄the picture point of monumented point correspondence on the plane of delineation, L _ijthat represent respectively is monumented point P on object _iand P _jdistance, l _ijthe distance of picture point, d _io _cto the distance of picture point, γ _ijoP _iand OP _jangle, A is the intersection point of four monumented points, B is the intersection point of four monumented point picture points, α ₁, α ₂respectively AP ₄and P ₁p ₄, P ₃p ₄the angle becoming, β ₁, β ₂respectively O _cb and O _cc ₁, O _cc ₃the angle becoming, θ is AP ₃, AP ₄the angle becoming, above these data all can be processed and measurement is obtained by image.Pixel coordinate (u, v) can be in the hope of by image processing algorithm, through conversion, tries to achieve picture coordinate (x _i, y _i) and the coordinate (x of intersection points B _b, y _b).D ₁, D ₂, D ₃, D ₄respectively O _cto P _idistance, can obtain through suitable algorithm:

$\left\{\begin{array}{c}\frac{D_1}{{\mathrm{<figure-callout\; id="3"\; label="D"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">D</figure-callout>}}_3}=\frac{L_{1a}\sin {\mathrm{\&beta;}}_2}{L_{3a}\sin {\mathrm{\&beta;}}_1}=\frac{L_{14}\sin {\mathrm{\&alpha;}}_2(x_b-x_3)\sqrt{x_1^2+{\mathrm{<figure-callout\; id="1"\; label="y"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">y</figure-callout>}}_1^2+f^2}}{L_{34}\sin {\mathrm{\&alpha;}}_1(x_1-x_b)\sqrt{x_3^2+{\mathrm{<figure-callout\; id="3"\; label="y"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">y</figure-callout>}}_3^2+f^2}}\\ {\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">D</figure-callout>}}_1^2+{\mathrm{<figure-callout\; id="3"\; label="D"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">D</figure-callout>}}_3^2-2D_1{\mathrm{<figure-callout\; id="3"\; label="D"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">D</figure-callout>}}_3\cos {\mathrm{\&gamma;}}_{13}=L_{13}^2\end{array}\right.$

Wherein

in like manner can also obtain D ₂, D ₄.

Determine the coordinate of four measuring monumented point center in camera coordinate system:

$(X_i,Y_i,Z_i)=\frac{(x_i,y_i,f)D_i}{\sqrt{x_{\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="HDA0000453144090000021.png,HDA0000453144090000033.png"\; state="\{\{state\}\}">i</figure-callout>}}^2+y_i^2+{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="HDA0000453144090000021.png,HDA0000453144090000033.png"\; state="\{\{state\}\}">f</figure-callout>}}^2}}$

Through above-mentioned coordinate conversion, can obtain the coordinate figure of four measuring monumented point center in world coordinate system

coordinate according to survey mark dot center under auxiliary coordinates coordinate figure under coordinate figure by survey mark dot center under world coordinate system and target coordinate system is brought formula into and is calculated auxiliary target coordinate system to rotation and the translation matrix of world coordinate system, coordinate according to gauge head center under auxiliary target coordinate system, calculates the world coordinates value at gauge head center.By movement, assist target to carry out multimetering to testee surface.

5. turn station measurement and data space splicing, because the one-shot measurement visual field of video camera is limited, while having determined to measure for some large-scale workpiece, video camera and tested part keep a relative position can not tested point on all parts be measured complete, so turning station measures, adjust the position of video camera and testee, make the one side of posting monumented point on auxiliary target mapping probe over against video camera, and the axis centre of paraphysis is positioned at and turns platform 0 scale mark place, and record the now position 1 of video camera, on position 1, carry out the measurement of the inner branch of apparent field, while wherein taking for the first time, will turn station can seem identification hole G on ball and be saved in set φ, after the impact point surveyed of position 1 is measured, video camera is adjusted to position 2, while adjusting position, turning station ball attitude does not change, rotate auxiliary target target survey rod makes the one side of posting monumented point over against video camera simultaneously, and guaranteeing to gather in φ has at least 3 identification holes visible in camera, coordinate figure (x according to each index aperture in auxiliary target coordinate system _fG, y _fG, z _fG), the coordinate figure that calculates index aperture world coordinate system at 1 place in position is that the coordinate figure in the world coordinate system at 2 places, position is

the transformational relation of twice position is:

$\left(\begin{array}{c}{x}_{w_1{G}_1}\\ y_{w_1{G}_1}\\ z_{w_1{\mathrm{<figure-callout\; id="1"\; label="G"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">G</figure-callout>}}_1}\\ 1\end{array}\right)=\left(\begin{array}{cc}{R}_{21}& t_{21}\\ 0^t& 1\end{array}\right)\left(\begin{array}{c}{x}_{w_2{G}_2}\\ y_{w_2{G}_2}\\ z_{w_2{\mathrm{<figure-callout\; id="2"\; label="G"\; filenames="HDA0000453144090000021.png,HDA0000453144090000033.png"\; state="\{\{state\}\}">G</figure-callout>}}_2}\\ 1\end{array}\right)$

G wherein ₂for the index aperture total with position 1 on position 2, G ₁for total index aperture corresponding in φ.

During shooting for the first time on position 2, according to and set φ in total index aperture calculating location 1 place world coordinate system and the coordinate transformation parameter R between the 2 place world coordinate systems of position ₂₁and t ₂₁, by the index aperture newly increasing on position 2 coordinate transformation parameter R ₂₁and t ₂₁convert, the structure after conversion is added in φ, thereby φ is upgraded.Continue on position 2 the impact point amount of carrying out, obtaining the coordinate figure of gauge head in the world coordinate system of position 2 is that wherein each measurement result is by coordinate transformation parameter R simultaneously ₂₁and t ₂₁be rotated and translation transformation, the measurement result at 2 gauge head centers in position

the result transforming under the world coordinate system at 1 place, position is:

$\left(\begin{array}{c}{x}_w\\ y_{\mathrm{<figure-callout\; id="1"\; label="w\; z\; w"\; filenames="HDA0000453144090000011.png,HDA0000453144090000021.png"\; state="\{\{state\}\}">w</figure-callout>}}& \\ z_w{}_{}\\ 1\end{array}\right)=\left(\begin{array}{cc}{R}_{21}& t_{21}\\ 0^t& 1\end{array}\right)\left(\begin{array}{c}{x}_{w_2}\\ y_{w_2}\\ {\mathrm{<figure-callout\; id="2"\; label="z\; w"\; filenames="HDA0000453144090000021.png,HDA0000453144090000033.png"\; state="\{\{state\}\}">z</figure-callout>}}_{w_{}}\\ 1\end{array}\right)$

Thereby according to above formula by two locational measurement result unification to coordinates, realizing three splicings measures, constantly adjust by that analogy the relative position between video camera and testee, until tested points all on heavy parts is measured complete, and by under each locational measurement result unification to coordinate system, realize the splicing of each position, thereby finally realize the three-dimensionalreconstruction to heavy parts.

The method that the present invention adopts video camera to turn station is carried out planning application to device under test best view, overcome the finiteness of video camera one-shot measurement visual field, expanded the scope of measuring, measure simultaneously auxiliary target put on turn on the outer surface of ball of station according to certain even angle at the crossover location of warp and parallel, arrange cylindrical hole, hole serves as a mark, the axis of cylindrical hole intersects with the centre of sphere of the ball of fighting in different parts, target turns pastes the circular thin subsides of colored light echo reflection that shades of colour is not identical on the ball cylindrical hole of station, the position of index aperture in auxiliary target determined by colour code is unique, thereby capture can stereoscopic vision and other vision measurement technology monumented point coupling difficult, three dimensions splices complicated technical barrier, realization is quick to heavy parts, high precision, automatically measure and rebuild on a large scale and cheaply.

Claims (6)

1. the monocular vision measuring method of a heavy parts, it is characterized in that, this measuring method is put on by auxiliary target turns the measurement of fighting in different parts that station ball is realized video camera, the auxiliary target using comprises a measuring staff, measuring staff top is rotatably equipped with station ball, and this turns on ball surface, station and is evenly laid with index aperture, is also installed with the measuring stick that can rotate with measuring staff on this measuring staff, on a face of this measuring stick, be provided with monumented point, described in turn ball below, station and be fixedly installed the platform that turns that is carved with angle value;

When described measuring method is measured, the one side that auxiliary target is put on be provided with monumented point is over against video camera, by video camera, obtain the characteristic image information of target monumented point, after measuring in video camera Yi Ge apparent field, mobile camera is to another position, assurance turns station ball pose and does not change, rotate measuring staff makes the one side of posting monumented point over against video camera simultaneously, and record the anglec of rotation of measuring staff, simultaneously by turning station ball and turning each index aperture on the ball of station, obtain turning and stand afterwards and turn the mutual relationship before station, by the mutual relationship between them, some groups of coordinate figures that obtain are carried out to space splicing to realize the reconstruct to heavy parts pattern.

2. the monocular vision measuring method of heavy parts according to claim 1, is characterized in that, described measuring method comprises the following steps:

1) video camera vision measurement system is demarcated, determined camera inner parameter and system structure parameter, auxiliary target is demarcated, determine and under auxiliary target coordinate system, turn each monumented point center and gauge head coordinate on Zhan Qiugekong center, survey rod;

2) one side of auxiliary target mapping probe being posted to monumented point, over against video camera, is obtained the characteristic image information of target monumented point by video camera;

3) the characteristic image information of the target monumented point collecting is carried out to image processing and obtain each monumented point center pixel coordinate;

4) according to pin-hole imaging principle, set up systematic survey model, the pixel coordinate at monumented point center is carried out to coordinate conversion and obtain the coordinate figure of survey mark dot center in world coordinate system, calculate auxiliary target coordinate system to rotation and the translation matrix of world coordinate system, according to calculated rotation and translation matrix and the gauge head center coordinate under auxiliary target coordinate system, calculate the world coordinates value at gauge head center;

5) after measuring in video camera Yi Ge apparent field, mobile camera, to another position, starts the measurement of another location, until all measurement of curved surface of heavy parts are complete;

6) according to the mutual relationship that turns position in coordinate figure in auxiliary target coordinate system of each uniquely identified hole on the ball of station and image coordinates system, the D coordinates value of respectively organizing obtaining is carried out to space splicing, finally realize the reconstruct to heavy parts object dimensional pattern.

3. the monocular vision measuring method of heavy parts according to claim 2, it is characterized in that, described step 2) when measuring, surveying excellent axis is positioned at and turns platform 0 scale place, and auxiliary target mapping probe posts monumented point one side over against video camera, when the rigid body measuring head of putting on when auxiliary target contacts with curved surface tested point is vertical, the switch synchro control video camera on gauge head obtains the characteristic image information of target monumented point, and image pick-up card gathers image.

4. the monocular vision measuring method of heavy parts according to claim 2, is characterized in that, in described step 4), auxiliary target coordinate system to the transformation for mula of world coordinate system is:

$\left(\begin{array}{c}{x}_w\\ y_w\\ z_w\\ 1\end{array}\right)=\left(\begin{array}{cc}{R}^{\&prime;}& t^{\&prime;}\\ 0^t& 1\end{array}\right)\left(\begin{array}{c}{x}_f\\ y_f\\ z_f\\ 1\end{array}\right)$

Wherein, (x _f, y _f, z _f, 1) ^t(x _w, y _w, z _w, 1) ^trespectively the coordinate of P in auxiliary target coordinate system and world coordinate system; R ' is the rotation matrix to world coordinate system by auxiliary target coordinate system, and t ' is the translation vector to world coordinate system by auxiliary target coordinate system.

5. the monocular vision measuring method of heavy parts according to claim 2, it is characterized in that, after described step 5) is measured in video camera Yi Ge apparent field, mobile camera is to another position, assurance turns station ball position and does not change and rotate auxiliary target target simultaneously and survey rod and make the one side of posting monumented point over against video camera, start the measurement of another location, realize and turn station measurement.

6. the monocular vision measuring method of heavy parts according to claim 2, it is characterized in that, described step 1) is carried out timing signal to video camera vision measurement system and is adopted auxiliary target to complete the demarcation of video camera, video camera and auxiliary target are fixed in a distance, open ccd video camera power supply; Within the scope of camera field of view, choose the summit of gauge block as calibration point, piece image is taken in position of every movement, and the two-dimensional image information of the monumented point of acquisition is transmitted and be saved in computing machine by network data line; The monumented point image coordinate of all positions of utilize extracting and corresponding the known world coordinate thereof, bring in pinhole imaging system Measuring System Models, and then complete the solving of camera interior and exterior parameter, and be saved in systems parameters document, in order to measuring phases, calls.

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