阅读说明：本技术 列车车轮的测量方法及相关系统 (Train wheel measurement method and related system ) 是由 达尼洛·德斯波西托 弗兰塞斯克-哈维尔·卡夫雷·普伊加利 帕乌·格拉塔科斯·马蒂 戴维·莫利 于 2019-05-30 设计创作，主要内容包括：本发明涉及一种用于测量列车(14)的至少一个车轮(12)的测量方法,包括以下步骤：获取步骤,在该获取步骤期间,当列车(14)在多个光学传感器(32)前方运动时,该多个光学传感器(32)获取车轮(12)的至少一部分的多个轮廓绘图步骤,在该绘图步骤期间,对于每个光学传感器(32),控制模块(30)将由光学传感器(32)获取的轮廓结合,以获得车轮(12)的一部分的图,该图进一步被转换为点群；重新结合步骤,在该重新结合步骤期间,将从光学传感器(32)获得的点群结合以形成车轮(12)的三维图像；以及分析步骤,在该分析步骤期间,在三维图像上测量多个参考点和参考距离。(The invention relates to a measuring method for measuring at least one wheel (12) of a train (14), comprising the following steps: an acquisition step during which, when the train (14) moves in front of the plurality of optical sensors (32), the plurality of optical sensors (32) acquire a plurality of profiles of at least a portion of the wheel (12), during which, for each optical sensor (32), the control module (30) combines the profiles acquired by the optical sensors (32) to obtain a map of a portion of the wheel (12), which is further converted into a group of points; a recombination step during which the groups of points obtained from the optical sensors (32) are combined to form a three-dimensional image of the wheel (12); and an analysis step during which a plurality of reference points and reference distances are measured on the three-dimensional image.)

1. A measurement method for measuring at least one wheel (12) of a train (14) using a measurement system (10), characterized in that the method comprises the steps of:

-an acquisition step (52) during which, when the train (14) is moving in front of a plurality of optical sensors (32), said plurality of optical sensors (32) acquire, by optical techniques, a plurality of profiles of at least a portion of said wheel (12);

-a mapping step (54) during which, for each optical sensor (32), the control module (30) combines all the profiles acquired by said optical sensor (32) to obtain a map of a portion of said wheel (12), which is further converted into a group of points;

-a recombining step (56) during which the groups of points obtained from the optical sensors (32) are combined to form a three-dimensional image of the wheel (12); and

-an analysis step (58) during which a plurality of reference points and reference distances are measured on the three-dimensional image.

2. the measuring method according to claim 1, characterized in that, before the acquisition step (52), the method further comprises a detection step (50) during which the train (14) is detected by an identification sensor (28) triggering the acquisition step.

3. the measurement method according to claim 1, characterized in that, during the acquisition step (52), at least one of the optical sensors (32) is an inner sensor (32A) that acquires a plurality of profiles of an inner portion of the wheel (12) and at least one of the optical sensors (32) is an outer sensor that acquires a plurality of profiles of an outer portion of the wheel (12).

4. The measurement method according to claim 1, characterized in that during the acquisition step (52), each optical sensor (32) acquires at least one hundred profiles of the portion of the wheel (12).

5. a method of measurement according to claim 1, wherein the optical technique is laser triangulation.

6. the measurement method according to claim 1, characterized in that during the analysis step (58), the wheel diameter is calculated from the reference distance and a previous measurement of the wheel diameter.

7. The measurement method according to claim 6, characterized in that the wheel diameter is calculated by the formula D ' -2 (FH-FH '), wherein D ' is a previous measurement of the wheel diameter, FH ' is a previous measurement of the flange height obtained simultaneously with D ', and FH is the flange height measured during the analysis step (58).

8. the measurement method according to any one of claims 1 to 7, wherein during the step of recombining (56), each profile of each group of points is combined with at least one corresponding profile from another group of points, forming a complete profile of the wheel (12), said complete profile forming a three-dimensional image of the wheel (12).

9. The measurement method according to claim 8, characterized in that during the analysis step (58) a normalized profile is determined from the full profile of the three-dimensional image as a full profile presenting a minimum measurement flange height.

10. A measurement system (10) for measuring at least one wheel (12) of a train (14), the measurement system (10) comprising:

-a control module (30) configured to implement the measurement method of claim 1; and

-a plurality of optical sensors (32) configured to acquire a plurality of profiles of a portion of the wheel (12).

11. the measurement system (10) of claim 10, wherein the measurement system (10) further comprises an identification sensor (28) adapted to detect the train (14) and trigger the acquiring step (54).

12. The measuring system (10) according to claim 10, characterized in that each optical sensor (32) comprises a laser source (34) adapted to project a light beam (38), a shaping device adapted to shape the light beam (38) into a planar light beam, and a camera (36) adapted to acquire an image of a contact area (40) between the light beam (38) and the wheel (12), the image containing a profile of the portion of the wheel (12), the control module (30) being configured to extract the profile from the image.

13. The measurement system (10) of claim 10, wherein the control module (30) is further configured to access a database containing data from previous measurements of the wheel (12).

Technical Field

The invention relates to a measuring method for measuring at least one wheel of a train using a measuring system. The invention also relates to a measuring system implementing said method.

background

During operation on a railway, the wheels of the train are subject to rolling wear and eventually need to be adjusted or, at worst, replaced. To account for wear, the diameter of each wheel of the train is typically measured during off-hours in the plant. The measurement of the diameter is typically done using hand tools and must be done on each wheel of the train, which can be time consuming and inaccurate.

Other measurement methods exist for solid objects in order to provide better accuracy, such as three-dimensional scanning. Three-dimensional scanning is a method of analyzing a real-world object or environment to collect shape data thereof. The collected data can then be used to construct a digital three-dimensional model. Many different techniques, in particular optical techniques, can be used to construct the scanning device.

Laser triangulation is an optical technique in which a laser source emits a beam that reflects off an object to be measured to be viewed by a camera located on the side of the laser beam. The light source, the object and the camera form a triangle allowing to relate the position of the reflected laser light to the distance between the light source and the object with high accuracy.

Laser triangulation is typically used for a stationary object scanned from each angle to reconstruct a three-dimensional model. However, this method is inefficient and not easy to operate, requiring disassembly of the wheel. Performing laser triangulation on a moving wheel is difficult because the point at which the laser beam is directed must allow diameter to be derived.

There is a need for a method of measuring train wheels by optical techniques such as laser triangulation which is both easy to implement and accurate in its results.

Disclosure of Invention

The invention therefore relates to a method of the above-mentioned type, characterized in that it comprises the following steps:

-an acquisition step, during which the plurality of optical sensors acquire, by optical techniques, a plurality of profiles of at least a portion of the wheel, while the train is moving in front of the plurality of optical sensors;

-a mapping step during which, for each optical sensor, the control module combines all the profiles acquired by the optical sensor to obtain a map of said portion of the wheel, which is further converted into a group of points;

-a recombination step during which the clusters of points obtained from the optical sensors are combined to form a three-dimensional image of the wheel; and

-an analysis step during which a plurality of reference points and reference distances are measured on the three-dimensional image.

According to advantageous but not mandatory further aspects of the invention, the method according to the invention may comprise the following features, alone or in any technically possible combination:

Before the acquisition step, the method further comprises a detection step during which the train is detected by the identification sensor, triggering the acquisition step;

-during the step of acquiring, the at least one optical sensor is an inboard sensor acquiring a plurality of profiles of an inboard portion of the wheel, and the at least one optical sensor is an outboard sensor acquiring a plurality of profiles of an outboard portion of the wheel;

-during the acquisition step, each optical sensor acquires at least one hundred profiles of a portion of the wheel;

-the optical technique is laser triangulation;

-during the analysis step, calculating the wheel diameter from the reference distance and the previous measurement of the wheel diameter;

-calculating the wheel diameter by the formula D ' -2 ═ FH-FH ', where D ' is the previous measurement of the wheel diameter, FH ' is the previous measurement of the flange height obtained simultaneously with D ', and FH is the flange height measured during the analysis step;

-during the step of recombining, each profile of each point group is combined with at least one corresponding profile from another point group, forming a complete profile of the wheel, said complete profile forming a three-dimensional image of the wheel; and

-during the analysis step, determining a normalized profile from the full profiles of the three-dimensional image as the full profile presenting the minimum measured flange height.

The invention also relates to a measuring system for measuring at least one wheel of a train, the measuring system comprising:

-a control module configured to implement the above-mentioned measuring method; and

-a plurality of optical sensors configured to acquire a plurality of profiles of a portion of the wheel.

According to other advantageous but not compulsory aspects of the invention, the system according to the invention may comprise the following features, alone or in any technically possible combination:

The measuring system further comprises an identification sensor adapted to detect the train and trigger the acquisition step;

-each optical sensor comprises a laser source adapted to project a light beam, a shaping device adapted to shape the light beam into a planar light beam, and a camera adapted to acquire an image of a contact area between the light beam and the wheel, said image containing a profile of a portion of the wheel, the control module being configured to extract the profile from the image; and

The control module is further configured to access a database containing data from previous measurements of the wheel.

Drawings

the invention will be better understood on the basis of the following description, which is given by way of illustrative example only and does not limit the scope of the invention. This description is given in correspondence with the appended figures, in which:

Figure 1 is a top view of a measurement system of a wheel of a train;

figure 2 is a front view of the functioning of the measuring system of figure 1;

FIG. 3 is a side view of the laser source of the system of FIGS. 1 and 2;

Figure 4 is a schematic representation of the system of figures 1 and 2 for a continuous scan of the wheel;

Figure 5 is a diagram of the profile of the wheel obtained from the scan of figure 4, in which reference distances are shown; and

FIG. 6 is a schematic view of the successive steps of the measurement method.

Detailed Description

A system 10 configured for measuring a wheel 12 of a train 14 is schematically illustrated in fig. 1. The system 10 is designed to implement a measurement method for measuring the wheel 12 based on optical techniques (e.g., laser triangulation).

The train 14 travels on tracks 16, the tracks 16 leading to a roof 18, the roof 18 protecting the system 10 from external conditions (e.g., rain). The system 10 is designed to perform a measurement method on the wheels 12 of a moving train 14 as the train 14 enters or leaves a roof 18.

in the following, the function of one wheel 12 will be described, but it must be noted that the function of the other wheels is similar.

the wheel 12 is mounted on an axle 20 passing through its center. As shown in fig. 2, the wheel 12 defines a cylindrical rolling surface 22, the cylindrical rolling surface 22 surrounding the periphery of the wheel 12 in contact with the rail 16. The rolling surface 22 is defined by a flange 24 on the inboard side of the wheel 12 relative to the train, the flange 24 having a diameter greater than the diameter of the rolling surface 22.

The train 14 includes an identification device, such as a radio frequency identification device, configured to signal the arrival of the train 14. The identification device 26 is located on the underside of the car body near the front end of the train 14.

The system 10 includes an identification sensor 28, such as a radio frequency identification sensor, adapted to detect the identification device 26 as the train 14 approaches the roof 18 to initiate a measurement method. An identification sensor 28 is located in the box disposed between the tracks 16 and detects the identification device 26 as the train 14 passes over it.

The system 10 includes a central control module 30 adapted to implement the sequential steps of the measurement procedure and collect measurement data to produce results. The control module 30 includes a processor 31A designed to execute computer programs, a memory module 31B designed to store and retrieve data, and a user interface 31C that allows an operator to interact with the control module 30. Finally, the control module 30 can access an external database to obtain data of previous measurements of the wheel 12.

The system 10 also includes four optical sensors 32 located within the roof 18 and placed in four boxes located on either side of each track 16. The four optical sensors 32 form two pairs of optical sensors 32, each pair of optical sensors 32 including an inboard sensor 32A located inside the track 16 and an outboard sensor 32B located outside the track 16. Each optical sensor 32 is designed to acquire, by optical techniques, a plurality of profiles of the wheel 12 passing in front of it.

As shown in fig. 2, each optical sensor 32 acquires the profile of the side of the wheel 12, the inner sensor 32A acquires the profile of the inner portion of the wheel 12, and the outer sensor 32B acquires the profile of the outer portion of the wheel 12. The optical sensor 32 is coupled to the control module 30 and the control module 30 begins to acquire and collect the results.

In the example shown, the optical technique is laser triangulation. As shown in fig. 2, each optical sensor 32 includes a laser source 34 and a camera 36.

the laser source 34 projects a beam 38 along a central axis of emission. The central axis of the launch lies in a plane that is substantially perpendicular to the rail 16.

the beam 38 is shaped into a planar beam by shaping means (not shown) placed on the laser source 34.

as can be seen in fig. 3, the planar beam 38 is tilted and forms a tilt angle γ with the direction of the track 16 in a vertical plane parallel to the track 16. The inclination angle γ is between 30 ° and 60 °, for example equal to 45 °.

the planar beam 38 forms a first angle alpha with a horizontal ground plane in a plane perpendicular to the track 16. Due to the inclination of the planar light beam 38, the first angle α varies between a lowest value α 1 and a highest value α 2 along the width of the planar light beam 38.

The planar beam 38 is directed to intersect the rear of the wheel 12 passing in front of the optical sensor 32, forming a contact area 40 with the wheel. The direction of movement of the train 14 is indicated by the arrows in figure 3.

The camera 36 has a central acquisition axis forming, in a plane perpendicular to the trajectory 16, a second angle β with the horizontal ground plane, the second angle β being outside a range comprised between a lowest angle α 1 and a highest angle α 2.

The camera 36 is adapted to acquire images of the contact area 40 between the planar beam 38 and the wheel 12 at a set acquisition frequency.

Each image of the contact region 40 is a two-dimensional image of a three-dimensional contour of a portion of the wheel 12 acquired by the camera 36. The image profiles from the series of images acquired by the optical sensor 32 form a series of parallel profiles of a portion of the wheel 12. The distance between successive profiles in the series depends on the speed of the train 14 relative to the acquisition frequency of the camera 36. The image is sent from the optical sensor 32 to the control module 30 for analysis.

The control module 30 is adapted to analyze the two-dimensional images acquired by each optical sensor 32 to extract three-dimensional contours and combine the contours to create a map of the wheel 12.

The control module 30 extracts the contour from the image by relating the distance between the laser source 34 and the contact area 40 to the position of the contact area 40 on the image acquired by the camera 36. This distance is obtained by known geometric methods through the lowest and highest values α 1 and α 2 of the first angle α, the second angle β and the tilt angle γ, and the relative positions of the source 34 and the camera 36.

The control module 30 is also adapted to calculate a normalized profile from the three-dimensional profiles and to detect a plurality of reference points and reference distances on these profiles, in particular in order to determine the radius of the wheel 12.

the control module 30 can ultimately store the results in the memory module 31B and display them to the operator via the interface 31C to verify or reject the operating condition of the wheel 12.

The method of measurement of the wheels 12 of the train 14 is derived from the structure of the measurement system 10 described above and will now be described in its entirety with reference to fig. 6.

the measurement method is performed on the wheels 12 of the train 14 as the train enters or leaves the roof 18.

in a detection step 50, the identification sensor 28 of the measurement system 10 detects the identification device 26 located on the train 14 as the train 14 passes the identification sensor 28. The identification sensor 28 sends a notification to the control module 30 and the control module 30 initiates an acquisition step 52.

during the acquisition step 52, the optical sensors 32 continuously acquire, by optical techniques, images of the wheels 12 passing in front of them. As mentioned before, the optical technique is for example laser triangulation.

Thus, each optical sensor 32 acquires a series of images, each image containing a contour or series of contours of a portion of the wheel 12. In the example shown in fig. 2, the inner optical sensor 32A acquires an image of an inner portion of the wheel 12, and the outer optical sensor 32B acquires a contour of an outer portion of the wheel 12. The optical sensor 32 then sends the series of images to the control module 30 for analysis.

In a mapping step 54, the control module 30 extracts contours from the image sent by the optical sensors 32 to create a series of contours of a portion of the wheel 12 for each optical sensor 32.

the series of profiles represents a large number of profiles of a portion of the wheel 12 depending on the speed of the train 14 relative to the acquisition frequency of the camera 36. For example, each optical sensor 32 acquires at least one hundred profiles of a portion of the wheel 12. The series of profiles is sent to the control module 30 and stored in the memory module 31B for analysis.

As previously described, during the mapping step 54, the profiles in each series of profiles are combined by the control module 30 in order to create a map of each portion of the wheel 12 as viewed by the optical module 32.

The map is then converted into a three-dimensional cluster of points, as shown in FIG. 4. The coordinates of each point in the three-dimensional point group depend on the distance between the optical sensor 32 and the point in the figure and the position of the optical sensor 32. The cluster of points includes all the contours in the series of contours that are parallel to each other, as shown in fig. 4.

in the recombining step 56, the three-dimensional point groups obtained from the inboard and outboard sensors 32A, 32B of the inboard and outboard portions of the wheel 12 are combined to form a three-dimensional image of the entire wheel 12. To this end, each profile of each point cluster is combined with a corresponding profile from each other point cluster to form a complete profile of both sides of the wheel 12. Thus, a three-dimensional image is formed of all the complete contours.

Then, the three-dimensional image is displayed to the operator who performs the examination through the user interface 31C and stored in the memory module 31B.

In an analysis step 58, a plurality of reference points and a plurality of reference distances are detected on each complete contour of the three-dimensional image.

A portion of one complete profile of the recombined three-dimensional point cloud is shown in fig. 5, imaging the rolling surface 22 and flange 24 of the wheel 12. The following reference points and reference distances are detected on the complete contour during the analysis step 58:

a first point 101 and a second point 102 having the same coordinates on the vertical axis and separated by a first predetermined distance D1 on the horizontal axis;

A third point 103 located on the inner portion of flange 24 and separated on the vertical axis from second point 102 by a second predetermined distance D2;

A fourth point 104, which presents the lowest coordinate on the vertical axis of the complete contour;

a flange width FW equal to the difference in coordinates on the horizontal axis between the first point 101 and the third point 103; and

A flange height FH equal to the difference in coordinates on the vertical axis between the second point 102 and the fourth point 104.

The first predetermined distance D1 is for example between 50mm and 100mm, in particular equal to 70 mm.

The second predetermined distance D2 is for example between 10mm and 20mm, in particular equal to 13 mm.

the flange height FH is calculated for each complete contour of the image in order to determine a normalized contour. The normalized profile is considered to be the complete profile with the lowest measurement of flange height FH. This is because the complete profile with the smallest distance between the flange top and the rolling surface 22, and therefore the lowest measured flange height FH, is the complete profile passing through the center of the wheel 12 and intersecting the circumference of the wheel 12 in an orthogonal direction.

Advantageously, points from a maximum of four complete contours in the series closest to the normalized contour are added to the normalized contour in order to increase the density of points in the normalized contour. This increase in dot density reduces the effect of acquisition errors and increases the number of dots to improve the accuracy of the calculation.

The wheel diameter D is determined from the normalized profile by the following equation: d '-2 ═ FH-FH'). Here, D ' is a previous measurement of the wheel diameter taken by the control module 30 from the database, and FH ' is a previous measurement of the flange height obtained at the same time as D ' and also taken from the database. FH is the flange height previously obtained on the normalized profile.

advantageously, D 'and FH' are measured on the wheel 12 immediately after the wheel 12 is manufactured with the lathe and stored in a database for use before the wheel 12 is installed on the train 14.

The determination of the wheel diameter from the flange height measurement and the previous value is more accurate than a direct measurement of the diameter. Direct measurement requires obtaining a complete profile across the wheel center and two opposing boundaries, which is difficult to achieve accurately.

In addition, several other reference distances may be measured on the normalized profile.

Other distances include flange back excess material, tread turnover, maximum step in the flange, flange profile radius, and back-to-back distance.

The flange back excess material is equal to the difference in coordinates on the horizontal axis between the first point 101 and the point on the horizontal axis of the normalized profile at which the coordinate on the horizontal axis is farthest from the coordinate on the horizontal axis of the first point 101.

the tread turn is equal to the difference between the flange back excess material and the nominal width NW taken from the database. The nominal width NW is measured on the wheel 12 just after the wheel 12 is manufactured with the lathe and stored in a database for use before the wheel 12 is installed on the train 14.

For example a nominal width NW between 100mm and 150mm, in particular equal to 135 mm.

Advantageously, the tread turn is taken equal to 0 if the normalized profile comprises less than three different points, which are further away on the horizontal axis from the first point 101 than the nominal width NW. This is also the case if a point further from the first point 101 than the nominal width NW is not within a predetermined correlation radius from at least one other point. This prevents a situation where points further from the first point 101 than the nominal width NW are the result of noise in the acquisition process and therefore have coordinates on the normalized profile that are not correlated with each other.

The largest step in the flange is considered to be the largest distance separating a point in the normalized profile from the next point when the normalized profile is considered in its entirety. The two points are considered to determine the maximum step in the flange only when the line passing through them forms an angle of less than 2 ° with the horizontal axis, so that only the points of the flange area from the normalized profile are considered.

The flange profile radius is determined on the normalized profile by finding several points separated by a predetermined distance for which the radius of curvature of the portion of the normalized profile between the points is smallest. The flange profile radius is considered to be the radius of curvature of the portion. For example the predetermined distance is 7.07 mm.

the back-to-back distance is considered to be the distance between the first point 101 of the wheel 12 and an equivalent point located at the same position on another wheel sharing the axle 20 with the wheel 12.