A vehicle-mounted wheel out-of-roundness online dynamic measurement method and device

Abstract

The invention discloses an on-board dynamic measurement method for wheel out-of-roundness. The method comprises: installing two line structured light sensors and a point laser rangefinder on a bogie at the bottom of a vehicle, and calibrating the positional relationship between the point laser rangefinder and the line structured light sensor; respectively measuring the ellipse contour lines where two sections of laser planes intersect with an axle, calculating the coordinates of the center of the ellipse according to the ellipse contour lines, converting the two ellipse coordinate points into a global coordinate system by applying a conversion matrix, and calculating the axis center line of the axle through a straight line passing through the two points; measuring the position of a rolling point on a wheel tread through the output of the point laser rangefinder, the coordinates of a point laser measurement origin in a global coordinate system, and a laser straight line equation, calculating the coordinates of the rolling point on the wheel tread in the global coordinate system, and calculating the wheel radius through the distance from the point to the center line of the axle; and obtaining the wheel out-of-roundness through the standard deviation of a plurality of groups of wheel radius measurement values.

Description

Technical Field

[0001] The invention relates to an on-board dynamic on-line measurement method and device for out-of-roundness of a wheel, belonging to the technical field of testing and measurement. Background Art

[0002] Wheel out-of-roundness is an important indicator that affects the running status and safety of trains. With the increase of train wheel mileage and the influence of body load, the surface shape of train wheels will gradually change, the wheel out-of-roundness will increase, aggravating wheel wear and causing vibration, noise and other adverse conditions.

[0003] At present, the methods for measuring wheel out-of-roundness mainly include offline contact measurement and online pressure indirect measurement. Offline contact measurement requires the wheel to be disassembled from the bogie and mounted on a special measuring device so that the wheel rotates one circle, and the wheel tread is measured using a fixed mechanical contact measuring device to obtain the jump amount of the wheel tread surface when the wheel rotates one circle, thereby calculating the wheel out-of-roundness. This method has high accuracy but low efficiency and requires the disassembly of the bogie; online pressure indirect measurement is to lay a pressure sensor along the rail. When the wheel rolls over the rail for one circle, the pressure on the rail during the travel is measured, and the wheel out-of-roundness is indirectly calculated from the change in pressure. This method cannot directly obtain the deformation size of the out-of-roundness, or uses an indirect calibration method to calculate, which has poor accuracy and is often difficult to detect for smaller deformations such as polygons. Summary of the invention

[0004] The purpose of the present invention is to provide a vehicle-mounted on-line dynamic measurement method and device for wheel out-of-roundness, so as to solve the problem that the prior art has poor accuracy and is often difficult to detect defects such as polygons and other smaller deformations.

[0005] A vehicle-mounted wheel out-of-roundness online dynamic measurement method, the method comprising:

[0006] Install two line structured light sensors and a point laser rangefinder on the bogie at the bottom of the vehicle, and calibrate the positional relationship between the point laser rangefinder and the line structured light sensor;

[0007] Measure the ellipse contours where the two laser planes intersect the axle respectively, calculate the coordinates of the ellipse center according to the ellipse contours, apply the transformation matrix to transform the two ellipse coordinate points to the global coordinate system, and determine a straight line through the two points to calculate the axle centerline;

[0008] The position of the rolling point on the wheel tread is measured by the output of the point laser rangefinder, as well as the coordinates of the point laser measurement origin in the global coordinate system and the laser straight line equation. The coordinates of the rolling point on the wheel tread in the global coordinate system are calculated by determining a straight line from two points, and the wheel radius is calculated by the distance from this point to the center line of the axle;

[0009] The wheel out-of-roundness is obtained by the standard deviation of multiple sets of wheel radius measurements.

[0010] Furthermore, the coordinates of the center of the ellipse are calculated using an ellipse fitting algorithm.

[0011] Furthermore, the method of applying the transformation matrix to transform the two ellipse coordinate points into the global coordinate system includes:

[0012] The global system calibration of the two line structured light sensors and the point laser rangefinder is completed by installing the device and the sawtooth target, and the output coordinates of the two line structured light sensors and the measurement point coordinates of the point laser rangefinder are calculated to unify the conversion matrix into a coordinate system.

[0013] Furthermore, the method of unifying into one coordinate system includes:

[0014] The target is installed so that two line structured light sensors project laser planes respectively, and the laser plane forms two sawtooth light strips after being modulated by the sawtooth target, and the measuring point of the point laser rangefinder is located on the edge of a certain tooth;

[0015] The laser projected by each line structured light sensor forms four broken lines on the surface of one tooth of the sawtooth target, and the broken points are recorded as P1, P2, P3; Q1, Q2, Q3, respectively, reading the coordinates of P1-P3 under one of the line structured light sensors, and reading the coordinates of Q1-Q3 under another line structured light sensor;

[0016] According to the coordinate values ​​of P1-P3, the 3D coordinate system of the line structured light sensor is converted to P2, with P2 as the origin, P1-P2 as the x-axis, P3-P2 as the y-axis, and the z-axis as the edge of the sawtooth target. The coordinate system transfer matrix is ​​[R1, T1]; the coordinate system is established on Q2, and the coordinate system transfer matrix is ​​[R2, T2]. Measure the distance of P2-Q2, recorded as D, and the two coordinate systems are unified through the z-axis difference D;

[0017] The distance between the measuring point M and P2 of the laser rangefinder is recorded as L, then the coordinates of point M in the P2 coordinate system are (0,0,L), and the reading of the laser rangefinder at this time is recorded as K1;

[0018] The target is translated to keep the target always perpendicular to the laser plane of the line structured light sensor, so that the measuring point of the laser rangefinder is located on the edge of a tooth again, denoted as M'. At this time, the point where the laser plane of the line structured light sensor intersects with the edge of the tooth is denoted as P2', and the coordinate of P2' in the P2 coordinate system is R1·P2'+T1. The distance between M' and P2' is measured as L', and the coordinate of M' in the P2 coordinate system is R1·P2'+T1+[0,0,L']T;

[0019] According to the coordinates of M and M' in the P2 coordinate system, the straight line equation of the laser rangefinder's measuring laser line in the P2 coordinate system can be calculated. According to the coordinates of K1 and M points and the straight line equation coordinates, the coordinates of the laser rangefinder's measuring origin in the P2 coordinate system can be located.

[0020] Furthermore, the angle of each tooth of the sawtooth target is 90°.

[0021] Furthermore, the sawtooth target is perpendicular to the laser plane of the structured light sensor.

[0022] A vehicle-mounted on-line dynamic measurement device for wheel out-of-roundness, comprising a first structured light sensor, a second structured light sensor, a point laser rangefinder and a sawtooth target;

[0023] The structured light sensor 1, the structured light sensor 2 and the point laser rangefinder are installed at the bottom of the train, the laser planes of the structured light sensor 1 and the structured light sensor 2 are installed in parallel, and the cross-sectional profiles of the two laser planes and the axle are obtained respectively;

[0024] The point laser rangefinder measures the position of the rolling point on the wheel tread, and obtains the radius through the distance between the rolling point and the axle axis;

[0025] The sawtooth target is arranged perpendicular to the laser plane of the structured light sensor.

[0026] Furthermore, the angle of each tooth of the sawtooth target is 90°.

[0027] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention uses lasers from two line structured light sensors to project onto the axle of the wheelset, and obtains two ellipse center points through ellipse fitting calculation, and the two points constitute the center line of the axle; a point laser rangefinder measures the rolling circle position of the wheel tread, measures the rolling circle point, and calculates the distance between the rolling circle point and the center line of the axle. After the train wheel travels one circle, the wheel out-of-roundness is obtained, the measurement accuracy is improved, online real-time measurement is realized, the measurement efficiency is improved, and the wheel out-of-roundness fault can be discovered in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the present invention;

[0029] Figure 2 It is a schematic diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0031] The present invention proposes a vehicle-mounted on-line dynamic measurement method for wheel out-of-roundness, the steps of which are as follows:

[0032] (1) Two linear structured light sensors and a point laser rangefinder are installed on the bogie at the bottom of the vehicle, ensuring that the two linear structured light sensors measure the wheelset axle and the laser planes are parallel to each other, so that the contours of the laser plane and the axle cross section can be measured; the point laser rangefinder measures the rolling point on the wheel tread.

[0033] (2) Using a special mounting device and a sawtooth target, the global system calibration of the two line structured light sensors and the point laser rangefinder is completed, and the output coordinates of the two line structured light sensors and the measurement point coordinates of the point laser rangefinder are calculated to unify the transformation matrix into a coordinate system.

[0034] (3) During measurement, two line structured light sensors measure the ellipse contours where the two laser planes intersect the axle, and use the ellipse fitting algorithm to calculate the coordinates of the ellipse center. The transformation matrix is ​​used to transform the two ellipse coordinate points into the global coordinate system, and the straight line passing through the two points is used to calculate the coordinate equation of the axle center line. Assume that the two-dimensional coordinates of the point on the ellipse arc are (x i ,y i ), there are n points in total, then the least square method is used to optimize the following objective function and fit the ellipse equation. The center point of the ellipse is: ((a+c) / 2, (b+d) / 2)

[0035]

[0036] (4) During measurement, the coordinates of the rolling point on the wheel tread in the global coordinate system are calculated using the output of the point laser rangefinder, the coordinates of the point laser measurement origin in the global coordinate system, and the laser line equation. The wheel radius is calculated using the distance from this point to the center line of the axle.

[0037] As the wheel rolls forward, the wheel radius is continuously measured. After traveling a certain distance, the standard deviation of the wheel radius measurement is calculated to obtain the wheel out-of-roundness.

[0038] Two line structured light sensors and a point laser rangefinder form a unified measurement system. The measurement results of the three measurement sensors are unified into one coordinate system using a special mounting device and a sawtooth target. The specific calibration method is as follows:

[0039] (1) The laser planes of the two linear structured light sensors are installed in parallel. A special mounting device is used to fix the sawtooth target, the measurement system consisting of the linear structured light sensor and the point laser rangefinder. The angle of each tooth of the sawtooth target is 90°. During installation, the sawtooth target is perpendicular to the laser plane of the structured light sensor, and the target can move up and down in parallel on the special mounting device.

[0040] (2) The target is installed at a certain position so that two line structured light sensors project laser planes respectively. The laser planes are modulated by the sawtooth target to form two sawtooth light strips. The measurement point of the point laser rangefinder is located on the edge of a tooth.

[0041] (3) The laser projected by each line structured light sensor forms four broken lines on the surface of a tooth of the sawtooth target, and the broken points are recorded as P1, P2, and P3; Q1, Q2, and Q3, respectively, and the coordinates of P1-P3 under sensor 1 are read; and the coordinates of Q1-Q3 under sensor 2 are read.

[0042] (4) Taking the line structured light sensor 1 as an example, according to the coordinate values ​​of P1-P3, the 3D coordinate system of the line structured light sensor is transformed to P2, with P2 as the origin, P1-P2 as the x-axis, P3-P2 as the y-axis, and the z-axis as the edge of the sawtooth target. The coordinate system transfer matrix is ​​recorded as [R1, T1]. Similarly, the coordinate system of the line structured light sensor 2 is established on Q2, and the coordinate system transfer matrix is ​​recorded as [R2, T2]. The distance of P2-Q2 is measured and recorded as D. The two coordinate systems are unified by the difference D on the z-axis.

[0043] (5) The distance between the measuring point M and P2 measured by the laser rangefinder is recorded as L. The coordinates of point M in the P2 coordinate system are (0, 0, L). The reading of the laser rangefinder at this time is recorded as K1.

[0044] (6) The target is translated, and the target is kept perpendicular to the laser plane of the line structured light sensor, so that the measurement point of the laser rangefinder is located on the edge of a tooth again, which is recorded as M'. At this time, the point where the laser plane of the line structured light sensor 1 intersects with the edge of the tooth is recorded as P2'. The coordinate of P2' in the P2 coordinate system is R1·P2'+T1. The distance between M' and P2' is L'. The coordinate of M' in the P2 coordinate system is R1·P2'+T1+[0,0,L']. T .

[0045] (7) Based on the coordinates of M and M' in the P2 coordinate system, the linear equation of the laser line measured by the laser rangefinder in the P2 coordinate system can be calculated. Based on the coordinates of K1, M points and the linear equation coordinates, the coordinates of the measurement origin of the laser rangefinder in the P2 coordinate system can be located. Then, for each subsequent measurement point of the laser rangefinder, the coordinate value of the measurement point in the P2 coordinate system can be calculated through the output of the rangefinder and the linear equation of the laser line.

[0046] The present invention provides a vehicle-mounted on-line dynamic measurement device for wheel out-of-roundness, comprising a first line structured light sensor, a second line structured light sensor, a point laser rangefinder and a sawtooth target;

[0047] The structured light sensor 1, the structured light sensor 2 and the point laser rangefinder are installed at the bottom of the train, the laser planes of the structured light sensor 1 and the structured light sensor 2 are installed in parallel, and the cross-sectional profiles of the two laser planes and the axle are obtained respectively;

[0048] The point laser rangefinder measures the position of the rolling point on the wheel tread, and obtains the radius through the distance between the rolling point and the axle axis;

[0049] The sawtooth target is arranged perpendicular to the laser plane of the structured light sensor, and the angle of each tooth of the sawtooth target is 90°;

[0050] The measurement system is composed of a linear structured light sensor and a point laser rangefinder, which is installed at the bottom of the train. The rolling points of the wheelset axle and the wheel tread are measured respectively. The wheel radius is obtained by calculating the distance from the rolling point to the wheel centerline. After the wheel rolls one circle, the radius jump is obtained and the wheel out-of-roundness is calculated.

[0051] Two linear structured light sensors are used to measure the wheel set axle. The laser planes of the two linear structured light sensors are installed in parallel, and the cross-sectional profiles of the two laser planes and the axle are obtained respectively. The ellipse center is calculated using the ellipse fitting algorithm, and the axle axis centerline is calculated using the two ellipse center points. A point laser rangefinder is used to measure the position of the rolling point on the wheel tread, and the radius can be calculated from the distance between the rolling point and the axle axis centerline.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A vehicle-mounted on-line dynamic measurement method for wheel out-of-roundness, characterized in that: The method comprises: Install two line structured light sensors and a point laser rangefinder on the bogie at the bottom of the vehicle, and calibrate the positional relationship between the point laser rangefinder and the line structured light sensor; Measure the ellipse contours where the two laser planes intersect the axle respectively, calculate the coordinates of the ellipse center according to the ellipse contours, apply the transformation matrix to transform the two ellipse coordinate points to the global coordinate system, and determine a straight line through the two points to calculate the axle centerline; The position of the rolling point on the wheel tread is measured by the output of the point laser rangefinder, as well as the coordinates of the point laser measurement origin in the global coordinate system and the laser straight line equation. The coordinates of the rolling point on the wheel tread in the global coordinate system are calculated by determining a straight line from two points, and the wheel radius is calculated by the distance from this point to the center line of the axle; The wheel out-of-roundness is obtained by the standard deviation of multiple sets of wheel radius measurements; The method of applying a transformation matrix to transform two ellipse coordinate points into a global coordinate system comprises: The global system calibration of the two line structured light sensors and the point laser rangefinder is completed by installing the device and the sawtooth target, and the output coordinates of the two line structured light sensors and the measurement point coordinates of the point laser rangefinder are calculated to unify the conversion matrix in one coordinate system; The method of unifying into one coordinate system includes: The target is installed so that two line structured light sensors project laser planes respectively, and the laser plane forms two sawtooth light strips after being modulated by the sawtooth target, and the measuring point of the point laser rangefinder is located on the edge of a certain tooth; The laser projected by each line structured light sensor forms four broken lines on the surface of one tooth of the sawtooth target, and the broken points are recorded as P1, P2, P3; Q1, Q2, Q3, respectively, reading the coordinates of P1-P3 under one of the line structured light sensors, and reading the coordinates of Q1-Q3 under another line structured light sensor; According to the coordinate values ​​of P1-P3, the 3D coordinate system of the line structured light sensor is converted to P2, with P2 as the origin, P1-P2 as the x-axis, P3-P2 as the y-axis, and the z-axis as the edge of the sawtooth target. The coordinate system transfer matrix is ​​[R1, T1]. The coordinate system is established on Q2, and the coordinate system transfer matrix is ​​[R2, T2]. The distance of P2-Q2 is measured, which is recorded as D. The two coordinate systems are unified through the difference D on the z-axis. The distance between the measuring point M and P2 of the laser rangefinder is recorded as L, then the coordinates of point M in the P2 coordinate system are (0, 0, L), and the reading of the laser rangefinder at this time is recorded as K1; The target is translated to keep the target always perpendicular to the laser plane of the line structured light sensor, so that the measuring point of the laser rangefinder is located on the edge of a tooth again, denoted as M'. At this time, the point where the laser plane of the line structured light sensor intersects with the edge of the tooth is denoted as P2', and the coordinate of P2' in the P2 coordinate system is R1·P2'+T1. The distance between M' and P2' is measured as L', and the coordinate of M' in the P2 coordinate system is R1·P2'+T1+[0,0,L']T; According to the coordinates of M and M' in the P2 coordinate system, the straight line equation of the laser rangefinder's measuring laser line in the P2 coordinate system can be calculated. According to the coordinates of K1 and M points and the straight line equation coordinates, the coordinates of the laser rangefinder's measuring origin in the P2 coordinate system can be located.

2. The on-board dynamic wheel out-of-roundness measurement method according to claim 1, characterized in that: The ellipse center coordinates are calculated using an ellipse fitting algorithm.

3. The on-board dynamic wheel out-of-roundness measurement method according to claim 1, characterized in that: The angle of each tooth of the sawtooth target is 90°.

4. The on-board dynamic out-of-roundness measurement method of a wheel according to claim 1, characterized in that: The sawtooth target is perpendicular to the laser plane of the structured light sensor.

5. A device comprising the on-board dynamic wheel out-of-roundness measurement method according to any one of claims 1 to 4, characterized in that: It includes structured light sensor 1, structured light sensor 2, point laser rangefinder and sawtooth target; The structured light sensor 1, the structured light sensor 2 and the point laser rangefinder are installed at the bottom of the train, the laser planes of the structured light sensor 1 and the structured light sensor 2 are installed in parallel, and the cross-sectional profiles of the two laser planes and the axle are obtained respectively; The point laser rangefinder measures the position of the rolling point on the wheel tread, and obtains the radius through the distance between the rolling point and the axle axis; The sawtooth target is arranged perpendicular to the laser plane of the structured light sensor.

6. The on-board dynamic wheel out-of-roundness measuring device according to claim 5, characterized in that: The angle of each tooth of the sawtooth target is 90°.

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