CN101825441B - Photoelectric measurement method for distance from railway gauge to platform - Google Patents

Abstract

The invention relates to a photoelectric measurement method for a distance from a railway gauge to a platform and relates to a method for measuring the distance between the center of the railway gauge and a side of the platform based on a double-linear structured light visual sensor. Based on the principle of the linear structured light visual sensor, the method realizes the measurement of the distance from the center of the railway gauge to the side of the platform by adopting double-linear structured light, realizes the measurement of the distance from the center of an air gauge to the side of the platform and non-contact, portable, movable and high-accuracy measurement by designing a double-linear structured light sensor and further improves the wide application of visual measurement technology.

Description

A kind of photoelectricity gauge-platform measurement method for distance

Technical field

The invention belongs to precision measurement method, particularly a kind of measuring method that realizes measuring distance between gauge center and the platform side based on the double structure light vision sensor.

Background technology

Need in the application of precision measurement in railway measurement etc., need carry out the measurement of geometric parameter to distance between gauge center and the platform side, thereby guarantee that train, rail, platform etc. are in safe range, guarantee the safe operation of railroad work, and safeguard for railroad data necessary is provided.

The platform dip stick based on the special use of physical construction is mainly adopted in the measurement of distance between traditional gauge center and the platform side, and the build heaviness is used complexity, and efficiency of measurement is low, and labour intensity is big, and is difficult in maintenance.Along with have noncontact, simple to operate, efficient is high, the appearance of the computer vision measurement technology of precision advantages of higher, has progressively obtained application at precision measurement scenes such as industry, traffic based on the measuring method of line structure optical sensor.Line structure optical sensor is by a video camera and a yi word pattern laser constitution, and cost is low, and volume is little, in light weight, in dimensional visual measurement, have broad application prospects, be applicable to the measuring system of industrial robot platform, also be applicable to outdoor traverse measurement able to programme system.But also there is not corresponding measuring method for distance between the gauge center of railway traffic, outdoor large and the platform side.Current surveying instrument is just directly measured to noncontact, light, removable measurement development by traditional contact, therefore how to adopt line structured light vision sensor that distance parameter measurement between gauge center and the platform side is become the major issue that railway traffic department needs to be resolved hurrily.

Summary of the invention

Technical matters: overcome the deficiencies in the prior art, provide a kind of and realize distance measurement method between gauge center and the platform side, the requirement of satisfy contactless in the rail measuring system, light, removable, high precision, easily calibrating based on line structure optical sensor.

Technical scheme: based on the principle of line structured light vision sensor, adopt double structure light, realize range observation between gauge center and the platform side, comprise the following steps:

This method adopts double structure light based on the principle of line structured light vision sensor, realizes range observation between gauge center and the platform side:

First two-laser, second two-laser are distributed in the video camera both sides and overlook the surveying instrument that rail constitutes light vision sensor; Fix by mechanical bayonet socket between surveying instrument and the platform, mechanical bayonet socket and platform first make contact, second contact point are with respect to video camera photocentre position O _cFixing; During measurement, make demands before the working range of need satisfied first two-laser, second two-laser and video camera and the measurement depth of field, and guarantee that first laser plane, second laser plane and rail intersect;

Obtain the optical strip image of structured light, obtain the image coordinate of 4 of striation focus point A, B, C, D that rail cover and first laser plane, second laser plane intersect according to characteristics of image, according to the line structured light vision sensor measurement model, by the image coordinate of 4 of striation focus point A, B, C, D obtain tested rail cover promptly first plane with respect to video camera photocentre O _cThe locus;

According to the line structured light vision sensor measurement model, volume coordinate by 4 of striation focus point A, B, C, D, obtain the coordinate of AB mid point E and CD mid point F, by the direction vector of straight line EF and rail cover promptly the normal vector on first plane calculate gauge center vertical plane promptly second plane with respect to video camera photocentre O _cThe locus; Utilize tried to achieve tested gauge center vertical plane promptly second plane with respect to video camera photocentre O _cThe locus, and tested platform edge machinery bayonet socket is with respect to video camera photocentre O _cPosition first make contact, second contact point, two point coordinate obtain the distance L between gauge center and the platform side.

According to the line structured light vision sensor measurement model, calculate the locus of tested rail cover with respect to the video camera photocentre;

According to the line structured light vision sensor measurement model, calculate the locus of gauge center vertical plane with respect to the video camera photocentre;

Utilize the locus with respect to the video camera photocentre of having tried to achieve tested gauge center vertical plane, and tested platform edge machinery bayonet socket is asked for the distance between gauge center and the platform side with respect to video camera photocentre position.

Beneficial effect: the inventive method has broken through the measurement scheme of traditional platform dip stick, based on the line structured light vision sensor principle, designed the double structure optical sensor, realized the measurement of distance between empty gauge center and the platform side, realize contactless, light, removable, high-acruracy survey, further promoted the vision measurement broad application.

Description of drawings

Fig. 1 is the synoptic diagram of surveying instrument measurement of the present invention and the mathematical principle figure of surveying instrument measurement space platform and gauge centre distance.

Fig. 2 is the perspective model of line structured light vision sensor.

Rail cover and optical plane intersected the striation synoptic diagram when Fig. 3 measured for surveying instrument of the present invention.

Have among the above figure: the bayonet socket 3 of platform plane 1, surveying instrument 2, surveying instrument and platform, the first line laser projector 4, the second line laser projector 5, video camera 6, the first laser light plane 7, the second laser light plane 8, rail 9, rail cover 10, gauge center vertical plane 11, laser light plane and rail cover intersection 12, key light bar straight line 13.

Embodiment

As shown in Figure 1, video camera 6 is overlooked rail, two-laser and is distributed in video camera 6 both sides and bows and throw rail 9, constitutes this sensing measurement instrument.Fix by mechanical bayonet socket 3 between surveying instrument and the platform 1, instrument machinery bayonet socket 3 and platform 1 contact point are with respect to video camera photocentre stationkeeping.During measurement, need satisfy the working range of laser instrument and video camera 6 and measure the depth of field before make demands, and guarantee that two laser planes and rail 9 intersect, this is realization easily in actual measurement.

Figure 2 shows that the perspective model of line structured light vision sensor.As shown in FIG., video camera 3D vision measurement model is usually based on pin-hole model.World coordinate system is consistent with the sensor light plane coordinate system, is made as O _w-x _wy _wz _w, its O _w-x _wy _wOverlap with optical plane.Photo coordinate system is O ₁-X ₁Y ₁, O wherein ₁Being the intersection point of optical axis with the picture plane, is the optical centre on picture plane.O ₁And O _cBetween be the effective focal length of object lens imaging apart from f.O wherein ₁X ₁Axle is along pixel horizontal direction, O _lY _lAxle is perpendicular to O _lX _lAxle.In computer picture,, be that initial point is set up image coordinate system Ouv promptly usually with the point of the O among Fig. 2 with the point in the upper left corner initial point as image coordinate.Camera coordinate system O _c-x _cy _cz _c, O wherein _cPoint is for the imaging centre of perspectivity, i.e. the optics principal point of object lens, O _cz _cBe the camera objective optical axis, perpendicular to CCD as the plane.O _cx _cAxle and O _cy _cAxle is parallel to O respectively _lX _lAxle and O _lY _lAxle.

With the line-structured light is example, and a word line laser instrument projects an optical plane and target to be measured meets at line L.P _wBe on the straight line L a bit, P _wAt world coordinate system O _w-x _wy _wz _w, camera coordinate system O _c-x _cy _cz _cAnd the respective coordinates under the computer graphic photo coordinate system Ouv is respectively (x _w, y _w, z _w), (x _c, y _c, z _c) and (x _l, y _l).Then the two-dimensional coordinate transformational relation under three dimensional space coordinate under the world coordinate system and the computer picture coordinate system is shown below:

$\mathrm{<figure-callout\; id="1"\; label="s\; u\; v"\; filenames="HSA00000123195800011.png"\; state="\{\{state\}\}">s</figure-callout>}\left[\begin{array}{c}u\\ v\end{array}\right]\left[\begin{array}{c}\\ 1\end{array}\right]=A\left[\begin{array}{c}{x}_c\\ y_c\\ z_c\end{array}\right]=A\left[\begin{array}{cc}R& T\end{array}\right]\left[\begin{array}{c}{x}_w\\ y_{\mathrm{<figure-callout\; id="1"\; label="w\; z\; w"\; filenames="HSA00000123195800011.png"\; state="\{\{state\}\}">w</figure-callout>}}& \\ z_w{}_{}\\ 1\end{array}\right]=\left[\begin{array}{ccc}\mathrm{\&alpha;}& \mathrm{<figure-callout\; id="0"\; label="c\; u"\; filenames="HSA00000123195800012.png"\; state="\{\{state\}\}">c</figure-callout>}& u_{}{}_0\\ 0& \mathrm{\&beta;}& v_0\\ 0& 0& 1\end{array}\right]\left[\begin{array}{cc}R& T\end{array}\right]\left[\begin{array}{c}{x}_w\\ y_w\\ z_w\\ 1\end{array}\right]---\left(1\right)$

Wherein, s is a modifying factor; R is a rotation matrix, and T is a translation vector, and R and T have determined direction and the position of video camera with respect to world coordinate system.Matrix A is the inner parameter matrix of linear system, wherein u ₀And v ₀Be O _lCoordinate under the computer picture coordinate, α and β are the scale factor (or be called effective focal length) of horizontal axis of ordinates corresponding to focal distance f, and c is the two coordinate axis out of plumb factors.

Promptly can obtain three dimensional space coordinate under the world coordinate system and the two-dimensional coordinate transformational relation under the computer picture coordinate system by prior demarcation like this, obtain the coordinate put in the three dimensions by the respective coordinates of putting on the computer picture easily.

As shown in Figure 1, the Measurement and analysis process adopts following agreement:

● video camera 6 photocentres are by symbol O _cExpression, two structured light light source are by symbol O ₁, O ₂Expression, the line structured light vision sensor measurement coordinate system is defined as and camera coordinate system O _c-x _cy _cz _cOverlap;

● to simplify the analysis, measure among a small circle in, think that two rails 9 are straight line, projecting point edge, platform plane also is a straight line.

● platform plane 1 projecting point and measuring instrument bayonet socket 3 meet at space M, N point, space M N line, the very outstanding edge line of platform; The O of M, N point and video camera photocentre _cRelative position is known when instrument is made, and under camera coordinate system, then the M point coordinate is (x _M, y _M, z _M), the N point coordinate is (x _N, y _N, z _N);

● optical plane π _S1Meet at an A, B, optical plane π with the lofty perch of tested rail _S2Meet at a C, D with the lofty perch of tested rail; Spatial point A, B, C, D copline are in plane Γ;

● on the Γ of plane, E is a line segment AB mid point, and F is a line segment CD mid point, straight line l _mCross E, F 2 points, plane Γ _mCross plane Γ and go up straight line l _mΓ is vertical with the plane.

1. the analytic equation of rail top plan Γ

When the laser plane of twice one word line laser instrument was surrendered two rails 9, there were four crossing striation zones in laser plane and orbit plane.As shown in Figure 3, because there is suitable height in orbit plane 10 apart from ground, according to perspective relation, originally be divided into two parts for a striation that obtains on the image: striation part 12 and key light bar straight line 13 that rail cover and laser plane intersect, and there is certain distance in this two parts striation on image.So on the optical strip image that obtains, according to this feature, can determine rail cover and the crossing striation part of laser plane on the plane of delineation by image processing algorithm, thereby obtain four striation central point territories of rail cover and laser plane intersection, try to achieve the focus point in these territories then respectively, promptly obtain the image coordinate of 4 of A, B, C, D.

According to line-structured light vision measurement model, try to achieve A, B, C, D respectively at 4 at camera coordinate system O _c-x _cy _cz _cUnder volume coordinate (x _A, y _A, z _A), (x _B, y _B, z _B), (x _C, y _C, z _C), (x _D, y _D, z _D), obvious any 3 conllinear not in these 4, then thus 4 utilize the analytic equation of least square fitting out-of-plane Γ to be:

Plane Γ: a ₁X+b ₁Y+c ₁Z+d ₁=0

The normal vector that then obtains the plane is

2. ask for middle vertical plane Γ _m

Known A, B, C, D four point coordinate, then on the Γ of plane, the coordinate (x of AB mid point E _E, y _E, z _E) and the coordinate (x of CD mid point F _F, y _F, z _F) be respectively:

Point E coordinate:

Point F coordinate:

Then cross 2 straight line l of E, F _mDirection vector be

Wherein:

a ₂＝x _E-x _F，b ₂＝y _E-y _F，c ₂＝z _E-z _F

Plane Γ _mNormal vector

With

And

Vertically, then Promptly

$\stackrel{\&RightArrow;}{{\mathrm{\&eta;}}_m}=(a_m,b_m,c_m),$ Wherein:

a _m＝b ₁c ₂-c ₁b ₂，b _m＝c ₁a ₂-a ₁c ₂，c _m＝a ₁b ₂-b ₁a ₂

Then the some French by the plane obtains plane Γ _mThe Representation Equation be:

a _m(x-x _E)+b _m(y-y _E)+c _m(z-z _E)＝0

3. ask platform edge to middle vertical plane Γ _mDistance L

Known platform edge point M (x _M, y _M, z _M), N (x _N, y _N, z _N) to plane Γ _mDistance be respectively L _M, L _N:

$L_M=\frac{|a_m(x_M-x_E)+b_m(y_m-y_E)+c_m(z_M-z_E)|}{\sqrt{{a_m}^2+{b_m}^2+{{\mathrm{<figure-callout\; id="2"\; label="c\; m"\; filenames="HSA00000123195800011.png"\; state="\{\{state\}\}">c</figure-callout>}}_m}^2}},$

$L_N=\frac{|a_m(x_N-x_E)+b_m(y_N-y_E)+c_m(z_N-z_E)|}{\sqrt{{a_m}^2+{b_m}^2+{{\mathrm{<figure-callout\; id="2"\; label="c\; m"\; filenames="HSA00000123195800011.png"\; state="\{\{state\}\}">c</figure-callout>}}_m}^2}}.$

Because in the actual conditions, straight line MN not necessarily with plane Γ _mParallel, then for guaranteeing safe distance, get in the distance minimum value as the distance L of platform to the gauge center:

L＝min(L _M，L _N)。

Claims (1)

1. photoelectricity gauge-platform measurement method for distance, it is characterized in that the principle of this method based on line structured light vision sensor, adopt double structure light, realize range observation between gauge center and the platform side: first laser instrument (4), second laser instrument (5) are distributed in video camera (6) both sides and overlook the surveying instrument (2) that rail (9) constitutes laser vision sensor; Fixing between surveying instrument (2) and the platform (1) by mechanical bayonet socket (3); Machinery bayonet socket (3) and platform (1) first make contact (M), second contact point (N) are with respect to video camera (6) photocentre position O _cFixing; During measurement, need to satisfy the working range of first laser instrument (4), second laser instrument (5) and video camera (6) and measure the depth of field before make demands, and guarantee that first laser plane (7), second laser plane (8) intersect with rail (9);

Obtain the optical strip image of structured light, obtain the image coordinate of 4 of striation focus point A, B, C, D that rail cover (10) and first laser plane (7), second laser plane (8) intersect according to characteristics of image, according to the line structured light vision sensor measurement model, by the image coordinate of 4 of striation focus point A, B, C, D obtain tested rail cover (10) promptly first plane (Γ) with respect to video camera photocentre O _cThe locus; Wherein on A, C, 2 rails that are positioned at rail (9), 2 of B, D are positioned on another root rail of rail (9);

According to the line structured light vision sensor measurement model, volume coordinate by 4 of striation focus point A, B, C, D, obtain the coordinate of AB mid point E and CD mid point F, by the direction vector of straight line EF and rail cover (10) promptly the normal vector of first plane (Γ) calculate gauge center vertical plane (11) the i.e. second plane (Γ _m) with respect to video camera photocentre O _cThe locus;

Utilize and tried to achieve tested gauge center vertical plane (11) the i.e. second plane (Γ _m) with respect to video camera photocentre O _cThe locus, and tested platform (1) edge machinery bayonet socket (3) is with respect to video camera photocentre O _cPosition first make contact (M), second contact point (N), two point coordinate obtain the distance L between gauge center and the platform side.

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