CN115112044A - Wheel set size measurement method based on light spot cloud data of multi-line structure - Google Patents
Wheel set size measurement method based on light spot cloud data of multi-line structure Download PDFInfo
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- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/08—Measuring arrangements characterised by the use of optical techniques for measuring diameters
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Abstract
The invention discloses a wheel set size measuring method based on light spot cloud data of a multi-line structure. The method comprises the following steps: firstly, acquiring three-dimensional multi-line point cloud data of the surface of a running train wheel set through a multi-line structured light measuring system arranged on a vehicle section main line, and classifying the data according to cross section outlines of different line structured lights and the surface of the wheel set; then fitting the outer side surface of the wheel set through a random consistency sampling algorithm to be used as a reference plane for measuring the size of the wheel set; determining tread feature points in the three-dimensional multi-line point cloud data according to the reference plane, and fitting a rolling circle through the tread feature points to obtain wheel diameter parameters of the wheel set; and finally, determining a wheel set rotating shaft based on the normal vector of the reference plane and the center of the rolling circle, establishing an auxiliary plane through the wheel set rotating shaft and the tread point cloud, obtaining a two-dimensional section contour line of the wheel set, and obtaining the rim parameters of the wheel set on the two-dimensional section contour line of the wheel set. The invention improves the precision and robustness of the wheel set size measurement.
Description
Technical Field
The invention relates to the technical field of automatic detection of wheel set sizes of urban rail trains, in particular to a wheel set size measuring method based on light spot cloud data of a multi-line structure.
Background
Along with the quantity continuous increase of city rail train, the mileage of moving is constantly increasing, and is also stricter to city rail train operation safety requirement. The wheel set is a key component of the urban rail train running part, and the running safety of the train and the riding experience of passengers are guaranteed. As an important part of the direct contact between the train and the track, the extrusion, friction and impact generated by acceleration, braking and steering of the train during running directly act on the wheel pair. The size structure of the wheel set is continuously worn, and when the mechanical structure and the size deformation of the wheel set exceed a certain range, potential safety hazards are generated. Therefore, the wheel set needs to be detected in time, the structural size of the wheel set is guaranteed to be within a safety range, and the operation safety of the train is further guaranteed.
The southwest traffic university and leading science and technology jointly research and develop wheel set on-line detection system LY series wheel set fault detection system, and this system utilizes line structure light measurement technique to realize the measurement of wheel set size, integrates techniques such as ultrasonic wave simultaneously, has realized more fault check functions such as tread scotch, and the system automation degree of detection is high, the function is complete, but the structure is complicated, with high costs, is unfavorable for extensive popularization. The invention patent of von heibo 2017, namely 'wheel multi-parameter online measuring system and measuring method based on structured light', discloses a wheel set measuring device based on multi-line structured light, but the measuring method is low in accuracy degree, and the accuracy of wheel set dimension measurement is to be improved.
Disclosure of Invention
The invention aims to provide a wheel set size measuring method based on light spot cloud data with a multi-line structure, which is suitable for a field operation environment, and has the advantages of high measuring speed, strong anti-interference capability and high measuring precision.
The technical solution for realizing the purpose of the invention is as follows: a wheel set size measurement method based on multi-line structure light spot cloud data comprises the following steps:
step 1, acquiring three-dimensional multi-line point cloud data of the surface of a running train wheel set through a multi-line structured light measurement system arranged on a train section main line;
step 2, classifying the three-dimensional multi-line point cloud data on the surface of the running train wheel set according to the cross section profiles of the intersection of different line structure lights and the surface of the wheel set;
step 3, fitting the outer side surface of the wheel set through a random consistency sampling algorithm according to the classified three-dimensional multi-line point cloud data in the step 2 to serve as a reference plane for measuring the size of the wheel set;
step 4, determining tread feature points in the three-dimensional multi-line point cloud data through the definition of rolling circles according to the reference plane in the step 3, and fitting the rolling circles through the tread feature points to obtain wheel diameter parameters of the wheel pair;
step 5, determining a rotating shaft of the wheel set based on the normal vector of the reference plane in the step 3 and the center of the rolling circle in the step 4;
step 6, establishing an auxiliary plane through the wheel set rotating shaft and the tread point cloud to obtain a two-dimensional section contour line of the wheel set;
and 7, obtaining the rim parameters of the wheel set on the two-dimensional section contour line of the wheel set.
Compared with the prior art, the invention has the remarkable advantages that: (1) based on light spot cloud data with a multi-line structure, the method can adapt to a field dynamic operation environment, and is high in measurement speed and strong in anti-interference capability; (2) the wheel set structural characteristics are combined to carry out three-dimensional measurement, the measurement theory is mature, and the precision is high; (3) a large amount of multi-line structured light three-dimensional point cloud data are utilized, and random errors can be effectively avoided.
Drawings
Fig. 1 is a schematic flow chart of a wheel set size measurement method based on multi-line structured light spot cloud data.
Fig. 2 is a schematic diagram of the hardware position laying structure in the invention.
Fig. 3 is a schematic diagram of the wheel set dimension measurement and the space structure of each feature of the wheel set in the present invention.
FIG. 4 is a graph of the results of fitting the outside reference plane in an example of the invention.
FIG. 5 is a schematic diagram of a wheel set rolling circle fitting result and a wheel diameter parameter calculation result in the embodiment of the invention.
FIG. 6 is a schematic auxiliary plan view for two-dimensional profile section extraction in an example of the present invention.
FIG. 7 is a data plot of a three-dimensional cross-sectional profile before extraction and a two-dimensional cross-sectional profile after extraction of a two-dimensional cross-sectional profile curve in an example of the present invention.
Fig. 8 is a graph showing a local curve fitting result and a feature point extraction result in the example of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings and examples.
With reference to fig. 1, the invention provides a wheel set dimension measurement method based on multi-line structure light spot cloud data, which comprises the following steps:
step 1, acquiring three-dimensional multi-line point cloud data on the surface of a running train wheel set through a multi-line structured light measurement system arranged on a train section main line;
step 2, classifying the three-dimensional multi-line point cloud data on the surface of the running train wheel set according to the cross section profiles of the intersection of different line structure lights and the surface of the wheel set;
step 3, fitting the outer side surface of the wheel set through a random consistency sampling algorithm according to the classified three-dimensional multi-line point cloud data in the step 2 to be used as a reference plane for measuring the size of the wheel set;
step 4, determining tread feature points in the three-dimensional multi-line point cloud data through the definition of rolling circles according to the reference plane in the step 3, and fitting the rolling circles through the tread feature points to obtain wheel diameter parameters of the wheel pair;
step 5, determining a rotating shaft of the wheel set based on the normal vector of the reference plane in the step 3 and the center of the rolling circle in the step 4;
step 6, establishing an auxiliary plane through a wheel set rotating shaft and the tread point cloud to obtain a two-dimensional section contour line of the wheel set;
and 7, obtaining the rim parameters of the wheel set on the two-dimensional section contour line of the wheel set.
Further, in step 1, three-dimensional multiline point cloud data of the surface of the running train wheel set is obtained through the multiline structured light measurement system installed on the vehicle section main line, and with reference to fig. 2, the method specifically includes the following steps:
the multi-line structured light measuring system arranged on the vehicle section positive line comprises collecting modules on the inner side and the outer side of a wheel, wherein each collecting module comprises a camera and a multi-line laser transmitter, and the equipment installation of the collecting modules on the inner side and the outer side is mirror symmetry relative to a track; the elevation angle of the camera is 45 degrees, the optical center position is flush with the rail waist, and the horizontal distance between the optical center position and the rail waist is 20 cm; the multi-line laser transmitter and the cameras on the same side are the same in height, arranged in parallel with the track and 35cm away from the cameras on the same side.
Further, the step 1 of obtaining three-dimensional multiline point cloud data of the surface of the running train wheel set by the multiline structured light measuring system installed on the vehicle section main line specifically comprises the following steps:
step 1.1, calibrating camera parameters;
step 1.2, calibrating a light plane equation of the multi-line structured light;
step 1.3, working of a multi-line laser transmitter and a camera when a train passes through to obtain a wheel set multi-line structured light picture;
and step 1.4, processing the original picture, and converting the two-dimensional image of the laser into three-dimensional multi-line point cloud data through a light plane equation.
Further, in step 2, the three-dimensional multi-line point cloud data of the surface of the running train wheel set is classified according to cross section profiles of different line structure lights and the surface of the wheel set, and the specific steps are as follows with reference to fig. 3:
step 2.1, setting phi as the surface of the wheel pair, and sequentially setting the light plane of the outer multi-line structure as pi from top to bottom 1 、π 2 、…、π k ；
Step 2.2, classifying the three-dimensional multi-line point cloud data on the surface of the running train wheel set according to the cross section profiles of the intersection of different line structure light and the surface of the wheel set, and using a set Q for the structure light spot cloud data on the light plane of the ith line structure light i Preservation of which 0<i<k, Q in the measurement coordinate system i Satisfies the following conditions:
Q i ＝{q|q＝(x,y,z),q∈Φ,q∈π i } (1)
wherein, pi i Expressing an ith optical plane equation, and phi expressing the surface of the wheel pair;
step 2.3, using a set Q for all three-dimensional multi-line point cloud data 0 Is represented by Q 0 Satisfies the following conditions:
Q 0 ＝Q 1 ∪Q 2 ∪…∪Q k (2)
further, in step 3, according to the classified three-dimensional multi-line point cloud data in step 2, the outer side surface of the wheel set is fitted through a random consistency sampling algorithm to serve as a reference plane for measuring the size of the wheel set, and the method specifically comprises the following steps:
step 3.1, setting a plane equation of the reference surface of the outer side of the wheel pair as follows:
z＝ax+by+c (3)
wherein a, b and c are plane equation parameters;
step 3.2 at Q 0 In the random selection of three points { p 1 (x 1 ,y 1 ,z 1 )、p 2 (x 2 ,y 2 ,z 2 )、p 3 (x 3 ,y 3 ,z 3 )}；
Step 3.3 by { p 1 (x 1 ,y 1 ,z 1 )、p 2 (x 2 ,y 2 ,z 2 )、p 3 (x 3 ,y 3 ,z 3 ) Determining a plane S, and determining plane equation parameters a, b and c through a formula (4);
step 3.4, set Q 0 The three-dimensional multi-line point cloud data points with the middle distance plane S not more than the threshold value epsilon are internal points of the plane S, and Q is assumed 0 Any three-dimensional multi-line point cloud data point p i (x i ,y i ,z i )∈Q 0 At a distance d from the plane S i The formula is as follows:
record that d is satisfied i The number of inner points less than or equal to epsilon;
step 3.5, repeating the steps 3.1 to 3.4, circulating for K times, selecting the plane with the most inner points as a best fitting plane S, and taking the corresponding inner point set as a best inner point set P, wherein the iteration times K are calculated by the formula (6):
wherein m is Q 0 The number of medium three-dimensional multi-line point clouds, n is the number of the three-dimensional multi-line point clouds according with the plane characteristics, phi is fitted to obtain the expected probability of the plane, and the value range is [0.95, 0.99 ]](ii) a When τ is n/m and n are sufficiently large, equation (6) is converted into:
1-(1-τ 3 ) K ＝φ (7)
further, in step 4, according to the reference plane in step 3, tread feature points are determined in the three-dimensional multi-line point cloud data through the definition of a rolling circle, and the rolling circle is fitted through the tread feature points to obtain wheel set wheel diameter parameters, which are specifically as follows:
step 4.1, determining a tread base point in each lateral surface profile:
from the plane equation (3) of the wheel set to the outside reference plane and the rim width W, the three-dimensional profile data set Q is obtained from the line structured light of each outside i Screening point cloud data closest to a tread base point: p is a radical of formula 1 、p 2 、…、p n Wherein p is i (x i ,y i ,z i )∈Q i And satisfies the following conditions:
step 4.2, determining a plane pi' where the rolling circle is located:
the spatial plane circle is on a plane, the rolling circle of the tread is parallel to the outer plane and is separated by W-70 mm, and according to the plane equation (3) of the reference plane of the wheel pair, the equation of the plane pi' where the rolling circle is located is determined as follows:
ax+by+c'＝z (10)
wherein c' is a constant term parameter;
4.3, constructing a constraint equation of the circle center through the base point of the tread:
a chord on the circle can be formed according to a connecting line of any two base points, the perpendicular bisector of any chord on the circle passes through the circle center, and a constraint equation of the circle center is constructed: setting the circle center as p 0 (x 0 ,y 0 ,z 0 ) Taking two points on the circle: p is a radical of 1 (x 1 ,y 1 ,z 1 )、p 2 (x 2 ,y 2 ,z 2 ) Is connected to p 1 、p 2 Obtaining:
passing through the chord
Midpoint p of 12 And the center p of the circle 0 The perpendicular bisector of (A) is:
by
The following can be obtained:
let Δ x 12 ＝x 2 -x 1 ，Δy 12 ＝y 2 -y 1 ，Δz 12 ＝z 2 -z 1 ，
Converting formula (12) to:
Δx 12 ·x 0 +Δy 12 ·y 0 +Δz 12 ·z 0 -l 1 ＝0 (13)
step 4.4, solving the circle center coordinate p by plane constraint chord perpendicular constraint 0 ：
Based on the correlation of the perpendicular bisector equations of the circle, k-1 linearly independent perpendicular bisector equations can be derived from the k observation points, and p 0 Satisfying formula (10), concurrently available:
order to
L＝[1 l 1 l 2 … l k-1 ] T Then, there are:
BX-L＝0 (15)
from the least square matrix method and the formula (15), X ═ X can be obtained 0 ,y 0 ,z 0 ] T Least squares solution of (c):
X＝(B T B) -1 B T L (16)
and 4.5, solving a curve equation of the wheel diameter d and the space plane circle through the circle center coordinate and the tread base point:
from the center coordinate p of equation (16) 0 ＝(x 0 ,y 0 ,z 0 ) Calculating each observation point p i Distance to the centre of a circle ri ：
The wheel diameter parameter, i.e. the fitting diameter d of the circle, is 2 times r i The average value is calculated by the formula:
the equation of the spatial plane circle of the combined (10) tread circle is as follows:
further, in step 5, the rotating shaft of the wheel set is determined based on the normal vector of the reference plane in step 3 and the center of the rolling circle in step 4, specifically as follows:
step 5.1 unitization of the outside group quasi-plane normal vector
Step 5.2, determining the rotating shaft of the wheel pair according to the normal vector of the reference plane and the center of the rolling circle
Further, step 6, establishing an auxiliary plane through the wheel set through the rotating shaft and the tread point cloud to obtain a two-dimensional section contour line of the wheel set, which is as follows:
6.1, selecting complete three-dimensional data points on the inner side and the outer side of the wheel as original three-dimensional sections;
step 6.2, get throughEstablishing an auxiliary plane by the over-rotation axis and any point p on the original section, and connecting p on the auxiliary plane 0 p，p 0 The included angle between p and the x axis, namely the rotating axis is theta, and the distance between the p point and the rotating axis of the wheel pair is the y coordinate of p in the orthogonal section coordinate system:
y＝|pp 0 |*sinθ (20)
the x coordinate of the point p in the normal section coordinate system satisfies the following conditions:
x＝|p 0 p|*cosθ+|Op 0 | (21)
step 6.3, in the three-dimensional space, the normal of the wheel outside plane equation
Is Op 0 Direction vector of (1), center of circle coordinate p of tread 0 And the three-dimensional coordinates of the p-point are known, so there are:
when the rotating shaft is known, a two-dimensional coordinate p' (X, Y) corresponding to the p point in the normal section coordinate system is obtained by combining equations (20) to (22) with respect to an arbitrary three-dimensional point p (X, Y, Z) in the section profile;
and 6.4, performing two-dimensional conversion on all data points in the three-dimensional section to obtain complete two-dimensional section contour data.
Further, in step 7, on the two-dimensional cross-sectional profile line of the wheel set, the rim parameters of the wheel set are obtained, specifically as follows:
7.1, establishing a two-dimensional coordinate system, taking the outer side surface as a y axis of the coordinate system, taking a rotating shaft as an x axis, taking the ordinate of the tread base point as the radius of a rolling circle in the coordinate system and taking the ordinate as 65mm away from the outer side surface, and performing translation of the coordinate axis according to the ordinate; the rim thickness characteristic point b is 10mm larger than a in the y direction, and the rim height characteristic point is the maximum point of the y coordinate;
7.2, carrying out local least square curve fitting on data points within the range of +/-0.3 mm of the abscissa of the ideal characteristic point to obtainTo the precise coordinates of the feature points, and then calculating the rim thickness S by equations (23) and (24) d And rim height S h ：
S d ＝x L -x b (23)
S h ＝y c -y a (24)
In the formula, x L Abscissa, x, representing medial base line b Is the abscissa of point b, y a ,y c Respectively, the ordinate of the feature points a, c.
The invention is described in further detail below with reference to the figures and the embodiments.
Example 1
Fig. 2 is a hardware installation schematic diagram of the inner and outer side measurement modules in the wheel set size measurement method based on the light spot cloud data of the multi-line structure, the inner and outer side cameras and the laser light source are symmetrical about the track, the included angle between the camera, the light source and the horizontal plane is 45 degrees, the outer side light source is multi-line laser, and the inner side light source is single-line laser. The distance between the measuring module and the track is 200mm, the distance between the camera and the light source is 350mm, and laser is finely adjusted, so that light of each line structure in the field of view of the camera is uniformly imaged on the surface of the wheel pair.
Step 1, completing the calibration of a measuring system, establishing a measuring coordinate system of the system, and determining equation parameters of an optical plane. When a train passes through the measuring system, a multi-line structured light picture of the surface of the wheel set is obtained, the original picture is processed, and three-dimensional point cloud data of the surface of the wheel set is obtained on the established coordinate system.
Step 2, as shown in the measurement schematic diagram of fig. 3, three-dimensional point clouds Q of light planes with different line structures are processed 0 A cross section contour point cloud set Q obtained by intersecting different line structure light and the wheel pair surface 1 、Q 2 、…、Q k 。
And 3, fitting an outer reference plane of the multi-line structured light point cloud by using a random consistency sampling algorithm, wherein a fitting result is shown in fig. 4, and an outer reference plane equation z is ax + by + c.
Step 4, obtaining rolling circle characteristic points through the outer side reference surface and the classified point cloud, then solving the rolling circle, wherein the solving result is shown in fig. 5, and the obtained circle center p0 of the rolling circle and the wheel diameter of the wheel are as follows: 840.352 mm.
Step 5, determining the rotating shaft of the wheel through the normal vector of the reference plane and the center of the rolling circle
An auxiliary plane is established through any point of the rotating shaft and the tread data points, and a schematic diagram of the auxiliary plane is shown in FIG. 6;
and 6, selecting proper line structured light data to extract a two-position section contour curve. As shown in fig. 7, the three-dimensional cross-sectional profile before extraction and the two-dimensional cross-sectional profile after extraction are shown.
And 7, performing local curve fitting on the extracted section data.
As can be seen from the two-dimensional cross-sectional profile data in fig. 7, the inner reference line is located on the line x-135.01, the position section of the tread base point is [64,66], the rim thickness feature point is between the sections [102, 106], and the rim height feature point is between the sections [118, 122 ]. A local least squares fit is made to the data points in these three intervals as shown in fig. 8. And positioning characteristic points in the local fitting curve, wherein the coordinates of the characteristic points are respectively as follows: a (65.01, -0.01), b (103.04, 9.99), c (119.58, 27.94).
The rim thickness is calculated by equation (23) and equation (24): s d 31.97mm, rim height: s h ＝27.95mm。
The wheel selected in the embodiment is a standard wheel in a laboratory, the wheel diameter of the wheel is 840.30mm, the height of the wheel rim is 28mm, and the thickness of the wheel rim is 32 mm. The measuring error of the measuring method is less than 0.1mm, and the measuring precision is far higher than the threshold requirement of 0.4 mm.
Claims (9)
1. A wheel set size measurement method based on light spot cloud data of a multi-line structure is characterized by comprising the following steps:
step 1, acquiring three-dimensional multi-line point cloud data of the surface of a running train wheel set through a multi-line structured light measurement system arranged on a train section main line;
step 2, classifying the three-dimensional multi-line point cloud data on the surface of the running train wheel set according to the cross section profiles of the intersection of different line structure lights and the surface of the wheel set;
step 3, fitting the outer side surface of the wheel set through a random consistency sampling algorithm according to the classified three-dimensional multi-line point cloud data in the step 2 to serve as a reference plane for measuring the size of the wheel set;
step 4, determining tread feature points in the three-dimensional multi-line point cloud data through the definition of rolling circles according to the reference plane in the step 3, and fitting the rolling circles through the tread feature points to obtain wheel diameter parameters of the wheel pair;
step 5, determining a rotating shaft of the wheel set based on the normal vector of the reference plane in the step 3 and the center of the rolling circle in the step 4;
step 6, establishing an auxiliary plane through the wheel set rotating shaft and the tread point cloud to obtain a two-dimensional section contour line of the wheel set;
and 7, obtaining the rim parameters of the wheel set on the two-dimensional section contour line of the wheel set.
2. The wheel set dimension measuring method based on the multi-line structure light spot cloud data as claimed in claim 1, wherein the multi-line structure light measuring system installed on the vehicle section main line in the step 1 is as follows:
the multi-line structured light measuring system arranged on the vehicle section positive line comprises collecting modules on the inner side and the outer side of a wheel, wherein each collecting module comprises a camera and a multi-line laser transmitter, and the equipment installation of the collecting modules on the inner side and the outer side is mirror symmetry relative to a track; the elevation angle of the camera is 45 degrees, the optical center position is flush with the rail waist, and the horizontal distance between the optical center position and the rail waist is 20 cm; the multi-line laser transmitter and the cameras on the same side are the same in height, arranged in parallel with the track and 35cm away from the cameras on the same side.
3. The wheel set dimension measuring method based on the multi-line structure light spot cloud data as claimed in claim 1, wherein the three-dimensional multi-line point cloud data of the surface of the wheel set of the running train is obtained by the multi-line structure light measuring system installed on the front line of the train section in the step 1, and the method specifically comprises the following steps:
step 1.1, calibrating camera parameters;
step 1.2, calibrating a light plane equation of the multi-line structured light;
step 1.3, working of a multi-line laser transmitter and a camera when a train passes through to obtain a wheel set multi-line structured light picture;
and step 1.4, processing the original picture, and converting the two-dimensional image of the laser into three-dimensional multi-line point cloud data through a light plane equation.
4. The wheel set dimension measuring method based on the multi-line structure light spot cloud data as claimed in claim 1, wherein the three-dimensional multi-line point cloud data of the surface of the running train wheel set in the step 2 is classified according to cross-sectional profiles of intersection of different line structure lights and the surface of the wheel set, and specifically, the method comprises the following steps:
step 2.1, setting phi as the surface of the wheel pair, and sequentially setting the light plane of the outer multi-line structure as pi from top to bottom 1 、π 2 、…、π k ；
Step 2.2, classifying the three-dimensional multi-line point cloud data on the surface of the running train wheel set according to the cross section profiles of the intersection of different line structure light and the surface of the wheel set, and using a set Q for the structure light spot cloud data on the light plane of the ith line structure light i Preservation of which 0<i<k, Q in the measurement coordinate system i Satisfies the following conditions:
Q i ＝{q|q＝(x,y,z),q∈Φ,q∈π i } (1)
wherein, pi i Expressing an ith optical plane equation, and phi expressing the surface of the wheel pair;
step 2.3, using a set Q for all three-dimensional multi-line point cloud data 0 Is represented by Q 0 Satisfies the following conditions:
Q 0 ＝Q 1 ∪Q 2 ∪…∪Q k (2)。
5. the wheel set dimension measuring method based on the multi-line structure light spot cloud data as claimed in claim 1, wherein the step 3 is to fit the outer side surface of the wheel set as a reference plane for wheel set dimension measurement by a random consistency sampling algorithm according to the classified three-dimensional multi-line point cloud data in the step 2, and specifically comprises the following steps:
step 3.1, setting a plane equation of the reference surface of the outer side of the wheel pair as follows:
z＝ax+by+c (3)
wherein a, b and c are plane equation parameters;
step 3.2 at Q 0 In the random selection of three points { p 1 (x 1 ,y 1 ,z 1 )、p 2 (x 2 ,y 2 ,z 2 )、p 3 (x 3 ,y 3 ,z 3 )}；
Step 3.3 by { p 1 (x 1 ,y 1 ,z 1 )、p 2 (x 2 ,y 2 ,z 2 )、p 3 (x 3 ,y 3 ,z 3 ) Determining a plane S, and determining plane equation parameters through an equation (4);
step 3.4, set Q 0 The three-dimensional multi-line point cloud data points with the middle distance plane S not more than the threshold value epsilon are internal points of the plane S, and Q is assumed 0 Any three-dimensional multi-line point cloud data point p i (x i ,y i ,z i )∈Q 0 At a distance d from the plane S i The formula is as follows:
record that d is satisfied i The number of inner points less than or equal to epsilon;
step 3.5, repeating the step 3.1-step 3.4 for K times, and selecting the plane with the most interior points as the best fitting plane S * The corresponding inner point set is the best innerA set of points P, wherein the number of iterations K is calculated by equation (6):
wherein m is Q 0 The number of medium three-dimensional multi-line point clouds, n is the number of the three-dimensional multi-line point clouds according with the plane characteristics, phi is fitted to obtain the expected probability of the plane, and the value range is [0.95, 0.99 ]](ii) a When τ is n/m and n are sufficiently large, equation (6) is converted into:
1-(1-τ 3 ) K ＝φ (7)
6. the wheel set dimension measurement method based on the light point cloud data of the multi-line structure as claimed in claim 1, wherein the step 4 is to determine the tread feature points in the three-dimensional multi-line point cloud data by defining the rolling circle according to the reference plane in the step 3, and to fit the rolling circle through the tread feature points to obtain wheel set wheel diameter parameters, which are as follows:
step 4.1, determining a tread base point in each outer side profile:
from the plane equation (3) of the wheel set to the outside reference plane and the rim width W, the three-dimensional profile data set Q is obtained from the line structured light of each outside i Screening point cloud data closest to a tread base point: p is a radical of 1 、p 2 、…、p n Wherein p is i (x i ,y i ,z i )∈Q i And satisfies the following conditions:
step 4.2, determining a plane pi' where the rolling circle is located:
the spatial plane circle is on a plane, the rolling circle of the tread is parallel to the outer plane and is separated by W-70 mm, and according to the plane equation (3) of the reference plane of the wheel pair, the equation of the plane pi' where the rolling circle is located is determined as follows:
ax+by+c'＝z (10)
wherein c' is a constant term parameter;
4.3, constructing a constraint equation of the circle center through the base point of the tread:
a chord on the circle can be formed according to a connecting line of any two base points, the perpendicular bisector of any chord on the circle passes through the circle center, and a constraint equation of the circle center is constructed: setting the circle center as p 0 (x 0 ,y 0 ,z 0 ) Taking two points on the circle: p is a radical of 1 (x 1 ,y 1 ,z 1 )、p 2 (x 2 ,y 2 ,z 2 ) Is connected to p 1 、p 2 Obtaining:
passing through the chord
Midpoint p of 12 And the center p of a circle 0 The perpendicular bisector of (A) is:
by
Obtaining:
let Δ x 12 ＝x 2 -x 1 ，Δy 12 ＝y 2 -y 1 ，Δz 12 ＝z 2 -z 1 ，
Converting formula (12) to:
Δx 12 ·x 0 +Δy 12 ·y 0 +Δz 12 ·z 0 -l 1 ＝0 (13)
step 4.4, solving the circle center coordinate p by plane constraint chord perpendicular constraint 0 ：
Based on the correlation of the perpendicular bisector equation of the circle, k-1 linearly independent perpendicular bisector equations are obtained through k observation points, and p 0 Satisfying formula (10), in combination:
order to
L＝[1 l 1 l 2 …l k-1 ] T Then, there are:
BX-L＝0 (15)
obtaining X ═ X by the least square matrix method and formula (15) 0 ,y 0 ,z 0 ] T Least squares solution of (c):
X＝(B T B) -1 B T L (16)
and 4.5, solving a curve equation of the wheel diameter d and the space plane circle through the circle center coordinate and the tread base point:
from the center coordinates p of formula (16) 0 ＝(x 0 ,y 0 ,z 0 ) Calculating each observation point p i Distance r to the center of a circle i ：
The wheel diameter parameter, i.e. the fitting diameter d of the circle, is 2 times r i Average value, the calculation formula is:
the equation of the spatial plane circle of the combined (10) tread circle is as follows:
7. the wheel set dimension measuring method based on the multi-line structure light spot cloud data as claimed in claim 1, wherein the wheel set rotating shaft is determined based on the reference plane normal vector in the step 3 and the rolling circle center in the step 4 in the step 5, specifically as follows:
step 5.1 unitization of the outside group quasi-plane normal vector
Step 5.2, determining the rotating shaft of the wheel pair according to the normal vector of the reference plane and the center of the rolling circle
8. The wheel set dimension measurement method based on the multi-line structure light spot cloud data as claimed in claim 1, wherein the step 6 is to establish an auxiliary plane through the rotating shaft and the tread point cloud to obtain a two-dimensional section contour line of the wheel set, and the method specifically comprises the following steps:
6.1, selecting complete three-dimensional data points on the inner side and the outer side of the wheel as original three-dimensional sections;
step 6.2, establishing an auxiliary plane through the rotating shaft and any point p on the original section, and connecting p on the auxiliary plane 0 p，p 0 The included angle between p and the x axis, namely the rotating shaft is theta, and the distance between the p point and the rotating shaft of the wheel pair is the y coordinate of the p in the normal section coordinate system：
y＝|pp 0 |*sinθ (20)
The x coordinate of the point p in the normal section coordinate system satisfies the following conditions:
x＝|p 0 p|*cosθ+|Op 0 | (21)
step 6.3, in the three-dimensional space, the normal of the wheel outside plane equation
Is Op 0 Direction vector of (1), center of circle coordinate p of tread 0 And the three-dimensional coordinates of the p-point are known, so there are:
when the rotating shaft is known, a two-dimensional coordinate p' (X, Y) corresponding to the p point in the normal section coordinate system is obtained by combining equations (20) to (22) with respect to an arbitrary three-dimensional point p (X, Y, Z) in the section profile;
and 6.4, performing two-dimensional conversion on all data points in the three-dimensional section to obtain complete two-dimensional section contour data.
9. The method for measuring the wheel set dimension based on the light spot cloud data with the multi-line structure as claimed in claim 1, wherein the rim parameters of the wheel set are obtained on the two-dimensional section profile line of the wheel set in the step 7, and specifically the following steps are carried out:
7.1, establishing a two-dimensional coordinate system, taking the outer side surface as a y axis of the coordinate system, taking a rotating shaft as an x axis, taking the ordinate of the tread base point as the radius of a rolling circle in the coordinate system and taking the ordinate as 65mm away from the outer side surface, and performing translation of the coordinate axis according to the ordinate; the rim thickness characteristic point b is 10mm larger than a in the y direction, and the rim height characteristic point is the maximum point of the y coordinate;
7.2, carrying out local least square curve fitting on data points within the range of +/-0.3 mm of the abscissa of the ideal characteristic point to obtain the accurate coordinates of the characteristic point, and then carrying out equation (23) and equation (24)) Calculating rim thickness S d And rim height S h ：
S d ＝x L -x b (23)
S h ＝y c -y a (24)
In the formula, x L Abscissa, x, representing medial base line b Is the abscissa of point b, y a ,y c Respectively, the ordinate of the feature points a, c.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115824070A (en) * | 2023-02-23 | 2023-03-21 | 湖南睿图智能科技有限公司 | Method and device for measuring size of steel rail piece |
| CN116336953A (en) * | 2023-05-30 | 2023-06-27 | 武汉工程大学 | System and method for measuring radius and depth of perforation model |
| CN117784169A (en) * | 2024-02-27 | 2024-03-29 | 唐山港集团股份有限公司 | 3D point cloud-based steel coil contour measurement method, equipment and medium |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115824070A (en) * | 2023-02-23 | 2023-03-21 | 湖南睿图智能科技有限公司 | Method and device for measuring size of steel rail piece |
| CN116336953A (en) * | 2023-05-30 | 2023-06-27 | 武汉工程大学 | System and method for measuring radius and depth of perforation model |
| CN116336953B (en) * | 2023-05-30 | 2023-08-11 | 武汉工程大学 | System and method for measuring radius and depth of perforation model |
| CN117784169A (en) * | 2024-02-27 | 2024-03-29 | 唐山港集团股份有限公司 | 3D point cloud-based steel coil contour measurement method, equipment and medium |
| CN117784169B (en) * | 2024-02-27 | 2024-05-07 | 唐山港集团股份有限公司 | 3D point cloud-based steel coil contour measurement method, equipment and medium |
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