An elevator brake shoe gap detection device based on laser profile sensor

Abstract

The present invention relates to a detection instrument. The purpose is to provide an elevator brake shoe gap detection device based on a laser profile sensor, which should have the characteristics of fast and efficient detection. The technical solution is: an elevator brake shoe gap detection device based on a laser profile sensor, comprising a base, a screw rod rotatably positioned on the base and driven by a motor, a laser profile sensor positioned on the base through a slider on a guide rail and driven by the screw rod, an industrial computer connected to the laser profile sensor through a data line and connected to the motor through a motor driver, and two clamping plates installed on the base for clamping and fixing with the wheel rim of the traction wheel.

Description

Technical Field

[0001] The invention relates to a detection instrument, in particular to an elevator brake shoe clearance detection device. Background Art

[0002] The elevator brake is a key device to ensure the safe operation of the elevator. The working principle of the brake shoe type elevator brake is to use the brake shoe to hold the moving parts of the traction machine to achieve the purpose of braking; therefore, it is necessary to check the wear of the brake shoe frequently to prevent accidents caused by brake failure. CN112197715B discloses a method for detecting the gap between the elevator brake wheel and the brake shoe based on image recognition; it includes the following steps: S1: obtaining the original image of the gap between the elevator brake wheel and the brake shoe, and preprocessing it; S2: performing contour detection on the preprocessed image to obtain the brake wheel contour and the brake shoe contour respectively; S3: extracting the arc contour of the brake wheel contour and the brake shoe contour respectively to obtain two target arc segments; S4: using the two target arc segments to calculate the actual width of the gap between the brake wheel and the brake shoe; compared with the prior art, it has the advantages of non-contact, safety and high efficiency. However, this method is relatively complicated, has many detection steps, and the detection efficiency needs to be improved. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned background technology and provide an elevator brake shoe gap detection device based on a laser profile sensor, which should have the characteristics of fast and efficient detection.

[0004] The technical solution provided by the present invention is:

[0005] An elevator brake shoe gap detection device based on a laser contour sensor comprises a base, a lead screw rotatably positioned on the base and driven by a motor, a laser contour sensor positioned on the base via a slider on a guide rail and driven by the lead screw, an industrial computer connected to the laser contour sensor via a data line and connected to the motor via a motor driver, and two clamping plates mounted on the base for clamping and fixing with the wheel rim of a traction wheel.

[0006] The base comprises a bottom plate and a first connecting plate and a second connecting plate which are fixed at one end of the bottom plate and arranged perpendicularly to the length direction of the bottom plate.

[0007] The guide rail is arranged in parallel with the lead screw.

[0008] The screw nut is meshed with the screw.

[0009] The traction wheel and the brake wheel are coaxially arranged.

[0010] A method for detecting the gap between brake shoes of an elevator brake based on a laser profile sensor is carried out in the following steps:

[0011] (1) The elevator is powered off and stopped. Then the detection device is fixedly clamped on the wheel rim of the traction wheel. The angle between the screw axis and the brake wheel tread axis L is adjusted to be less than 10 degrees. The laser profile sensor is adjusted so that the center of a row of parallel line lasers emitted by it is aligned with the gap between the brake shoe and the brake wheel tread, and the angle α between the gap and the normal line of the brake shoe end face is 40-75 degrees. The gap is the gap between the working surface of the brake shoe and the corresponding part of the brake wheel tread. The brake wheel tread is the part where the outer circumference of the cylindrical brake wheel matches the working surface of the brake shoe.

[0012] (2) Turning on the motor drives the slider to move linearly on the guide rail, thereby driving the laser profile sensor to perform a line laser scan on the gap; the scanning data received by the laser profile sensor is also sent to the industrial computer;

[0013] (3) The industrial computer reads the scanning data of the laser profile sensor to obtain the three-dimensional point cloud of the brake shoe gap and the brake wheel surface and brake shoe end surface nearby;

[0014] (4) calculating the gap width and the gap unevenness based on the point cloud data obtained by scanning;

[0015] (5) Determine whether the gap is qualified based on the calculated gap width and unevenness.

[0016] The row of parallel line lasers in step (1) is formed by arranging a plurality of single beam line lasers, and the arrangement direction is perpendicular to the axis of the screw rod; the line lasers are perpendicular to the axis of the screw rod.

[0017] The line laser in step (1) is a 2D laser with a narrow measurement range, so that each cross-sectional data scanned only includes two surfaces: the brake shoe end face and the brake wheel tread.

[0018] In the scanning data of step (3), each cross-section data is line profile scanning data after the laser profile sensor moves a tiny distance d under the control of the industrial computer; the tiny distance d is 10 microns to 5000 microns.

[0019] The number of scans of the laser profile sensor is N, that is, the laser profile sensor moves N-1 times.

[0020] The calculation steps in step (5) are as follows:

[0021] (1) Based on the 3D Hough transform point cloud plane detection algorithm, identify the point cloud belonging to the brake shoe end surface;

[0022] (2) The remaining three-dimensional point cloud data is used as the point cloud of the brake wheel tread, and the side surface fitting of the cylindrical brake wheel is performed to obtain the expression of the central axis L and the radius R of the fitted brake wheel tread;

[0023] (3) In the point cloud of the brake shoe end face, calculate the distance from each point to the axis L of the brake wheel tread, find the N points with the smallest distance and their distance D from the axis L. i (i=1,2,…,N);

[0024] (4) Calculate the above N distances D i The average value of minus the radius R is taken as the width of the gap;

[0025] (5) Calculate the above N distances D i The standard deviation of is taken as the unevenness of the gap.

[0026] The fitting method of the expression of the central axis L of the brake wheel tread is:

[0027] (1) The known brake wheel tread point cloud data set is (x i ,y i ,z i ), i=1,2,…,M;

[0028] Assuming that the expression of axis L is ax+by+cz+d=0, the problem of solving the expression of axis L can be converted into the following optimization problem:

[0029] Optimization goal:

[0030] Constraints: a, b, c, d are all real numbers and cannot be 0 at the same time;

[0031] (2) The above optimization problem is solved using a genetic algorithm, and the obtained a, b, c, d are the parameters of the expression of the axis L, thus obtaining the expression of the axis L.

[0032] The calculation method of the brake wheel tread radius R is:

[0033] (1) According to the distance formula from a point in space to a straight line The brake wheel tread point cloud data set is (x i ,y i ,z i ), i = 1, 2, ..., M; calculate the distance d from each point to the axis L i , i=1,2,…,M:

[0034] (2) Get the distance d from all points to the axis L i Finally, find their average value and get the radius R of the brake wheel tread.

[0035] The beneficial effects of the present invention are:

[0036] Since the 2D line laser of the laser profile sensor is used for detection, not only can the degree of wear of the brake shoe be clearly measured to make a judgment on whether it is qualified, but also the operation steps and calculation workload are simplified, which significantly improves work efficiency, reduces detection time, and improves the detection accuracy of the elevator brake shoe gap. The present invention can also calculate the unevenness of the elevator brake shoe gap, providing a quantitative basis for judging the working condition of the elevator brake shoe. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the main structure of the device embodiment of the present invention.

[0038] Figure 2 1 is a diagram showing the relative positions of the screw axis, the brake wheel tread axis and the brake shoe end face in the embodiment.

[0039] Figure 3 3 is a relative position diagram of the line laser of the laser profile sensor, the axis of the brake wheel tread and the end face of the brake shoe in the embodiment.

[0040] Figure 4 Schematic diagram of a point cloud obtained by line laser scanning of a laser profile sensor in an embodiment.

[0041] Figure 5 yes Figure 3 Schematic diagram of the scanning detection state of the laser profile sensor on the gap.

[0042] Figure 6 Schematic diagram of the positional relationship between the present invention and the traction sheave rim in the embodiment.

[0043] Markings in the figure:

[0044] The first connecting plate 1, the base plate 2, the slider 3, the guide rail 4, the second connecting plate 5, the motor 6, the motor driver 7, the screw 8, the screw axis 8-1, the industrial computer 9, the first clamping plate 10, the line laser 11 (emitted by the laser contour sensor 12), the laser contour sensor 12, the second clamping plate 13, the brake wheel 14, the brake wheel tread 14-1, the brake wheel tread axis L, the brake shoe 15, the brake shoe end face 15-1, the gap 16, the three-dimensional point cloud 17, and the wheel rim 18. DETAILED DESCRIPTION

[0045] The present invention will be further described below by way of the embodiments shown in the accompanying drawings.

[0046] (1) The elevator brake shoe gap detection device based on the laser contour sensor provided by the present invention includes a first connecting plate 1, a bottom plate 2, a slider 3, a transverse support plate 4, a second connecting plate 5, a motor 6, a motor driver 7, a screw 8, an industrial computer 9, a first clamping plate 10, a line laser 11, a laser contour sensor 12, a second clamping plate 13, a brake wheel 14, a brake wheel tread 14-1, a brake shoe 15, a brake shoe end face 15-1, a gap 16, and a three-dimensional point cloud 17.

[0047] (2) The first clamping plate 10 and the second clamping plate 13 are made with 90-degree right-angle clamps, which can be fixedly clamped on the rim of the traction wheel (such as Figure 6 ), a screw hole is made on the second clamping plate 13, and the present invention can be clamped and fixed on the wheel rim of the traction wheel through a bolt matched with the screw hole.

[0048] (3) The first connecting plate 1 and the second connecting plate 5 are fixed at both ends of the bottom plate, and the two ends of the screw rod 8 are respectively mounted on the first connecting plate and the second connecting plate through bearings; the screw rod is equipped with a screw nut; the motor 6 is fixed on the second connecting plate, and the motor output shaft is connected to the screw rod 8 through a coupling. The guide rail 4 is fixed on the bottom plate 2 and is parallel to the screw rod axis; the slider 3 is slidably positioned on the guide rail and is connected to the screw rod nut.

[0049] (4) The laser profile sensor 12 is fixedly connected to the slider. The row of parallel line lasers emitted by the laser profile sensor is formed by arranging a plurality of single line lasers 11. The arrangement direction X of the line lasers is perpendicular to the screw axis 8-1, and the emission direction Z of the line lasers is also perpendicular to the screw axis (see Figure 3 ).

[0050] (5) When the motor drives the lead screw 8 to rotate, it can drive the slider 3 to move in a straight line, thereby driving the laser profile sensor to perform a straight line scan.

[0051] (6) The motor 6 and the motor driver 7 are electrically connected via a data line, and the industrial computer 9 controls the motor driver; the data of the laser profile sensor 12 is also sent to the industrial computer (equipped with a display).

[0052] When working, first the elevator is powered off and stopped. The device is clamped and fixed on the rim of the traction wheel by the first clamping plate and the second clamping plate; then the motor is controlled to rotate by the industrial computer, thereby rotating the screw to push the slider; by adjusting the positions of the two clamping plates, the laser profile sensor is adjusted so that the center of a row of line lasers emitted by it is aligned with the gap 16 between the quasi-brake shoe and the brake wheel tread 14-1, and the angle α between the normal line of the brake shoe end face is 40-75 degrees. The gap is the gap between the working surface of the brake shoe and the corresponding brake wheel tread. The brake wheel tread is the part on the outer circumference of the cylindrical brake wheel that is frictionally matched with the working surface of the brake shoe.

[0053] (7) During operation, the industrial computer controls the laser profile sensor to move a small distance d, and then the industrial computer reads the line profile scanning data of the laser profile sensor; after the scanning is completed, a three-dimensional point cloud 17 of the brake shoe gap and the brake wheel surface and brake shoe surface nearby can be obtained.

[0054] (8) A 2D laser with a narrow measurement range is used to avoid scanning the back surface of the brake shoe, so that each cross-sectional data scanned only contains the two surfaces of the brake shoe end face and the brake wheel tread.

[0055] (9) The number of times the laser profile sensor scans is recorded as N, that is, the laser profile sensor moves N-1 times.

[0056] Considering that the point cloud data obtained after scanning includes two surfaces, namely the brake shoe end surface and the brake wheel tread surface. The brake shoe end surface is considered to be a plane, and the brake wheel tread is a partial side surface of the cylindrical brake wheel. Considering that the scanning laser of the laser profile sensor is not necessarily completely perpendicular to the gap, the following algorithm needs to be used to calculate the width of the brake shoe gap.

[0057] Description: Except Figure 6 outside, Figure 2-Figure 5 The brake shoe in the figure only shows part of the structure.

[0058] The gap width is calculated based on the scanned point cloud data. The algorithm steps are as follows:

[0059] (1) Based on the 3D Hough transform point cloud plane detection algorithm, the point cloud belonging to the brake shoe end face is identified (existing technology, which will not be described here);

[0060] (2) The remaining three-dimensional point data is used as the brake wheel tread point cloud, and the side surface of the cylindrical brake wheel is fitted to obtain the expression of the central axis L and the radius R of the fitted brake wheel tread;

[0061] (3) In the point cloud of the brake shoe end face, calculate the distance from each point to the axis L of the brake wheel tread, and find the N points with the smallest distance and their distances Di (i = 1, 2, ..., N) from the axis L;

[0062] (4) Calculate the average of the N distances Di (i = 1, 2, ..., N) and subtract the radius R to obtain the gap width.

[0063] (5) Calculate the standard deviation of the above N distances Di (i=1, 2, ..., N) as the unevenness of the gap.

[0064] (6) Determine whether the brake shoe gap is qualified based on the set gap width and unevenness.

[0065] The laser profile sensor is preferably the MV-DP2060-01H laser profile sensor of Hikvision, with a measurement range (X axis) of about 29 mm, a Z axis resolution of 1.8 μm to 3.0 μm, and an X axis point cloud data interval of 12.3 μm to 16.8 μm. Based on the design and algorithm steps of the present invention, the detection accuracy of the brake shoe gap width can reach the micron level.

[0066] Example 1

[0067] The device of the present invention is used to detect and scan the clearance of the brake shoe of a certain elevator to obtain three-dimensional point cloud data;

[0068] Next, for the scanned point cloud data, the 3D Hough transform point cloud plane detection algorithm is used to identify the point cloud belonging to the brake shoe end face; the remaining point cloud is the brake wheel tread point cloud data, the set is (xi, yi, zi), i = 1, 2, ..., M, and the coordinate data of some points are as follows:

[0069] [10.002,3.015,201.013]

[0070] [10.013,3.114,201.101]

[0071] [10.242,3.201,199.927]

[0072] …

[0073] Using the above optimization method (using genetic algorithm to solve the optimization problem, the obtained a, b, c, d are the parameters of the expression of the axis L, thus obtaining the expression of the axis L), the fitted expression of the brake wheel tread axis L is 1.009x+0.002y+0.998z+197.213=0;

[0074] The radius of the brake wheel tread obtained by fitting is R = 203.5 mm;

[0075] Then, the distance from each point in the brake shoe end face point cloud to the tread axis L is calculated respectively, and the N points with the smallest distance and their distances Di (i=1, 2, ..., N) from the axis L are found; in this embodiment, N=10, and the distances from the 10 points with the smallest distance to the axis L are 203.931, 203.928, 203.930, 203.933, 203.929, 203.929, 203.934, 203.927, 203.935, 203.933, in mm respectively;

[0076] Then calculate the average of these 10 distances and subtract the radius R to get the width of the gap.

[0077] Average value = (203.931+203.928+203.930+203.933+203.929+203.929+203.934+203.927+203.935+203.933) / 10

[0078] =203.9315;

[0079] Average value minus radius R: 203.9315-203.5=0.4315mm;

[0080] Therefore, the gap width of the brake shoe in this example is 0.4315 mm.

[0081] Next, calculate the standard deviation, which is a measure of how much a set of data deviates from the mean.

[0082] The formula for calculating the standard deviation is as follows:

[0083] Standard deviation = sqrt((1 / 10)×[(203.931-203.9315)2+(203.928-203.9315)2+(203.930-203.9315)2+(203.933-203.9315)2+(203.929-203.9315)2+(203.929-203.9315)2+(203.934-203.9315)2+(203.927-203.9315)2+(203.935-203.9315)2+(203.933-203.9315)2])

[0084] =sqrt((1 / 10)×[0.0000225+0.0002025+0.0000625+0.0002025+0.0000625+0.0000625+0.0002025+0.0003025+0.0003025+0.0002025])

[0085] =sqrt(0.001)

[0086] =0.0316;

[0087] Therefore, the standard deviation of these 10 numbers is 0.0316 mm; which is an indicator of the unevenness of the gap.

[0088] By comparing the gap width of 0.6 and unevenness of 0.05 set for the elevator, it can be judged that the elevator is qualified.

Claims

1. A method for detecting the gap between brake shoes of an elevator brake based on a laser profile sensor is carried out in the following steps: (1) The elevator is powered off and stopped, and then the detection device is fixedly clamped on the rim of the traction wheel, and the angle between the axis of the screw and the axis of the brake wheel tread is adjusted to be less than 10 degrees. The laser profile sensor is adjusted so that the center of a row of parallel line lasers emitted by it is aligned with the gap (16) between the brake shoe and the brake wheel tread, and the angle (α) between the gap and the normal line of the brake shoe end face is 40-75 degrees; the gap is the gap between the working surface of the brake shoe and the corresponding part of the brake wheel tread; the brake wheel tread is the part on the outer circumference of the cylindrical brake wheel that has friction fit with the working surface of the brake shoe; (2) Turning on the motor drives the slider to move linearly on the guide rail, thereby driving the laser profile sensor to perform a line laser scan on the gap; the scanning data received by the laser profile sensor is also sent to the industrial computer; (3) The industrial computer reads the scanning data of the laser profile sensor to obtain the three-dimensional point cloud of the brake shoe gap and the brake wheel surface and brake shoe end surface nearby; (4) Calculate the gap width and gap unevenness based on the point cloud data obtained by scanning; (5) Determine whether the gap is qualified based on the calculated gap width and unevenness; The elevator brake shoe gap detection method adopts an elevator brake shoe gap detection device based on a laser profile sensor, comprising a base, a screw rod (8) rotatably positioned on the base and driven by a motor, a laser profile sensor (12) positioned on the base via a slider (3) on a guide rail (4) and driven by the screw rod, an industrial computer (9) connected to the laser profile sensor via a data line and connected to the motor (6) via a motor driver (7), and two clamping plates mounted on the base for clamping and fixing with the wheel rim (18) of the traction wheel; The base comprises a bottom plate (2), and a first connecting plate (1) and a second connecting plate (5) fixed at two ends of the bottom plate and arranged perpendicular to the length direction of the bottom plate; The guide rail is arranged in parallel with the lead screw; the traction wheel is arranged coaxially with the brake wheel.

2. The elevator brake shoe gap detection method based on laser profile sensor according to claim 1 is characterized in that: The row of parallel line lasers in step (1) is formed by arranging a plurality of single line lasers, and the arrangement direction is perpendicular to the axis of the screw rod; the axis of the line laser is perpendicular to the axis of the screw rod.

3. The elevator brake shoe gap detection method based on laser profile sensor according to claim 2 is characterized in that: The line laser in step (1) is a 2D laser with a narrow measurement range, so that each cross-sectional data scanned only includes the two surfaces of the brake shoe end face and the brake wheel tread.

4. The elevator brake shoe gap detection method based on laser profile sensor according to claim 3 is characterized in that: In the scanning data of step (3), each cross-sectional data is obtained under the control of the industrial computer, and the laser profile sensor moves a small distance. d Line profile scan data afterwards.

5. The elevator brake shoe gap detection method based on laser profile sensor according to claim 4 is characterized in that: The calculation steps in step (5) are as follows: (1) Based on the 3D Hough transform point cloud plane detection algorithm, identify the point cloud belonging to the brake shoe end surface; (2) The remaining 3D point data is used as the brake wheel tread point cloud, and the side surface of the cylindrical brake wheel is fitted to obtain the expression of the central axis L and radius of the fitted brake wheel tread. R ; (3) In the point cloud of the brake shoe end face, calculate the distance from each point to the axis L of the brake wheel tread, and find the point with the shortest distance. N points and their distances from the axis L D i , i =1,2,…,N; (4) Calculate the above N distances D i The average value of R , as the width of the gap; (5) Calculate the above N distances D i The standard deviation of is taken as the unevenness of the gap.

6. The elevator brake shoe gap detection method based on laser profile sensor according to claim 5; characterized in that: The fitting method of the expression of the central axis L of the brake wheel tread is: (1) The known brake wheel tread point cloud data set is ( x i , y i , z i ), i =1,2,…,M; Assume that the expression of axis L is a x +b y +c z +d=0, then solving the axis L expression can be converted into the following optimization problem: Optimization goal: min Constraints: a , b , c , d All are real numbers and cannot be 0 at the same time; (2) Using genetic algorithm to solve the above optimization problem, we get a , b , c , d That is the parameter of the expression of axis L, thus deriving the expression of axis L.

7. The elevator brake shoe gap detection method based on laser profile sensor according to claim 6; characterized in that: The calculation method of the brake wheel tread radius R is: (1) According to the distance formula from a point in space to a straight line , the brake wheel tread point cloud data set is ( x i , y i , z i ), i =1,2,…, M, calculate the distance from each point to the axis L d i , i =1,2,…,M; (2) Get the distances of all points to the axis L d i Finally, find their average value and get the radius R of the brake wheel tread.

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