A method for calculating the center of cabin workpiece based on laser ranging

Abstract

The present invention relates to the field of intelligent assembly technology, solves the technical problems of low automation and low efficiency in determining the axis center line of a cabin in the prior art, and particularly relates to a cabin workpiece center solution method based on laser ranging, comprising the following steps: S1, using a plurality of laser displacement sensors to respectively measure the distance from the surface of a standard cabin model to each laser displacement sensor, and determining the center coordinates of the standard cabin model according to the distance; S2, using three laser displacement sensors to respectively measure the distance from the surface of the cabin to be measured to each laser displacement sensor, and determining the center coordinates of the cabin to be measured according to the distance. The present invention not only improves the automation level of determining the axis center line of the cabin, but also greatly improves the efficiency, and at the same time can facilitate the azimuth adjustment according to the axis center lines of the two cabins, thereby ensuring the assembly efficiency of the docking of the two cabins.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent assembly, and in particular to a method for calculating the center of a cabin workpiece based on laser ranging. Background Art

[0002] The precision docking assembly system needs to align the centers of the two cabins before docking. In order to achieve high-precision alignment, it is necessary to accurately measure the spatial position of the center of each cabin. The general measurement method is to measure the center points of two cross-sections in a cabin, and then connect the two center points to form the axis of the cabin.

[0003] In the field of turning or milling, in order to determine the center of the tool, the contact method is often used to determine the tool center, that is, assuming that the center line of the measuring tool is parallel to the center line of the workpiece, the measuring tool is moved toward the workpiece from one direction of the X direction to make them contact each other, and the coordinates at the time of contact are recorded. Then, the measuring tool is moved toward the workpiece from another direction of the X direction to make them contact each other, and the coordinates at the time of contact are recorded. The average of the two recorded coordinates is the X coordinate of the center of the workpiece. The same method can be used to obtain the Y coordinate of the center of the workpiece.

[0004] However, this method can determine the tool center position with high accuracy, but it requires a set of precision motion mechanisms, relies on the precise motion of the measuring tool and manual visual judgment, has a low degree of automation and low efficiency when used, and is not suitable for determining the workpiece center in the field of automatic assembly. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a method for calculating the center of a cabin workpiece based on laser ranging, which solves the technical problems of low automation and low efficiency in determining the axis centerline of the cabin in the prior art.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for calculating the center of a cabin workpiece based on laser ranging, the method comprising the following steps:

[0007] S1. Use a number of laser displacement sensors to measure the distance from the surface of the standard cabin model to each laser displacement sensor, and determine the center coordinates of the standard cabin model according to the distance;

[0008] S2, using three laser displacement sensors to measure the distance from the surface of the test cabin to each laser displacement sensor, and determining the center coordinates of the test cabin according to the distance;

[0009] S3, based on the central coordinates of the standard cabin model, calculating the central position deviation of the cabin to be tested relative to the standard cabin model;

[0010] S4, determining the equation of the straight line corresponding to the axis line according to the center coordinates of the cabin to be tested;

[0011] S5. Adjust the orientation of the cabin to be tested according to the straight line equation corresponding to the axis center line.

[0012] Furthermore, in step S1, a plurality of laser displacement sensors are used to measure the distance from the surface of the standard cabin model to each laser displacement sensor, and the center coordinates of the standard cabin model are determined according to the distance. The specific process includes the following steps:

[0013] S11, making the central axis of the standard cabin model and the plane formed by the three laser displacement sensors perpendicular to each other;

[0014] S12. With the center of the standard cabin model as the origin and the positive direction of the x-axis as the starting point, three laser displacement sensors are arranged at 0°, 180° and 270° of the standard cabin model respectively. The coordinates of the three laser displacement sensors are , as well as ;

[0015] S13, obtaining the measurement data of the laser displacement sensor, then the distances from the surface of the standard cabin model to each laser displacement sensor are respectively , as well as ;

[0016] S14, according to the coordinates of three laser displacement sensors , as well as and distance , as well as Calculate the coordinates of the measured points on the cabin surface , as well as ;

[0017] S15, according to the coordinates of the measured points on the cabin surface , as well as Determine the center coordinates of the standard cabin model.

[0018] Furthermore, in step S2, three laser displacement sensors are used to measure the distance from the surface of the cabin to be measured to each laser displacement sensor, and the center coordinates of the cabin to be measured are determined according to the distances. The specific process includes the following steps:

[0019] S21, let the spatial coordinates of the three points on the surface of the test cabin be , , , the coordinates of the space center C of the test cabin are , the radius of the cabin to be tested is R;

[0020] S22. Determine three measured points , , With the center of the space The plane equation of the plane;

[0021] S23, according to the measured point , , With the center of space The plane equation of the plane is used to calculate the center coordinates of the cabin to be measured.

[0022] Further, in step S22, the plane equation is:

[0023]

[0024] In the above formula, , , , They are:

[0025]

[0026]

[0027]

[0028] .

[0029] Furthermore, in step S23, the calculation formula of the center coordinates of the cabin to be measured is:

[0030]

[0031] In the above formula, , , , is a known quantity.

[0032] Furthermore, in step S3, based on the central coordinates of the standard cabin model, the central position deviation of the cabin to be tested relative to the standard cabin model is calculated, which specifically includes:

[0033] According to the center coordinates of the standard cabin model and the center coordinates of the test cabin Calculate the center position deviation E.

[0034] Furthermore, in step S4, the axis of the cabin to be tested The corresponding straight line equation is:

[0035]

[0036] In the above formula, the spatial center coordinates of the cross sections at both ends of the measuring cabin are and , then the space center coordinates and The axis line of the test cabin .

[0037] By means of the above technical solution, the present invention provides a method for calculating the center of a cabin workpiece based on laser ranging, which has at least the following beneficial effects:

[0038] The present invention adopts a non-contact laser distance measurement method to determine the coordinates of points on the surface of the cabin, and calculates the center coordinates of the cabin by determining the center of a space circle through the distance of three points on the surface of the cabin. Therefore, the axis line of the cabin can be determined without using a precision motion mechanism, and the speed of measuring the coordinate points on the surface of the cabin is faster and more convenient, which not only improves the degree of automation for determining the axis line of the cabin, but also greatly improves the efficiency. At the same time, it is convenient to adjust the orientation according to the axis lines of the two cabins to ensure the assembly efficiency of the docking of the two cabins. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0040] Figure 1 It is a flow chart of the method for calculating the center of a cabin workpiece of the present invention;

[0041] Figure 2 It is a schematic diagram of calculating the centerline coordinates of the standard cabin model under the ideal state of the present invention;

[0042] Figure 3 It is a schematic diagram of calculating the center coordinates of the cabin to be measured under the general state of the present invention;

[0043] Figure 4 This is a schematic diagram of the cabin cross section when tilted 5° according to the present invention;

[0044] Figure 5 It is a schematic diagram of the cabin cross section when tilted 2° according to the present invention;

[0045] Figure 6 The relationship diagram between the cabin end surface translation and the axis centerline deflection angle of the present invention is shown;

[0046] Figure 7 It is a simplified schematic diagram of the shaft deflection model of the present invention;

[0047] Figure 8 It is a schematic diagram of determining the center of a space circle in a three-dimensional space coordinate system of the present invention;

[0048] Fig. 9 It is a schematic diagram of solving the cabin axis line in the three-dimensional space coordinate system of the present invention. DETAILED DESCRIPTION

[0049] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0050] Those skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, so the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0051] Please refer to Figure 1-Figure 9 , showing a specific implementation of this embodiment. This embodiment adopts a non-contact laser ranging method to determine the coordinates of points on the surface of the cabin, and calculates the center coordinates of the cabin by determining the center of a space circle by the distance of three points on the surface of the cabin. Therefore, there is no need to use a precision motion mechanism to determine the axis line of the cabin, and the speed of measuring the coordinate points on the surface of the cabin is faster and more convenient, which not only improves the degree of automation for determining the axis line of the cabin, but also greatly improves the efficiency. At the same time, it is convenient to adjust the orientation according to the axis lines of the two cabins to ensure the assembly efficiency of the docking of the two cabins.

[0052] Please refer to Figure 1 This embodiment proposes a method for calculating the center of a cabin workpiece based on laser ranging, and the method includes the following steps:

[0053] S1. Use a number of laser displacement sensors to measure the distance from the surface of the standard cabin model to each laser displacement sensor, and determine the center coordinates of the standard cabin model according to the distance;

[0054] Specifically, in this step, the standard cabin model is a standard cabin model in an ideal state within a plane formed by several laser displacement sensors. Using a standard cabin model, three precise laser displacement sensors are used to measure the distance from the surface of the standard cabin model to each laser displacement sensor, thereby determining the center coordinates of the standard cabin model.

[0055] In step S1 of this embodiment, in order to clearly and completely illustrate the specific implementation method of step S1, the specific process of step S1 includes the following steps:

[0056] S11, making the central axis of the standard cabin model and the plane formed by the three laser displacement sensors perpendicular to each other;

[0057] S12. With the center of the standard cabin model as the origin and the positive direction of the x-axis as the starting point, three laser displacement sensors are arranged at 0°, 180° and 270° of the standard cabin model respectively. The coordinates of the three laser displacement sensors are , as well as ;

[0058] S13, obtaining the measurement data of the laser displacement sensor, then the distances from the surface of the standard cabin model to each laser displacement sensor are respectively , as well as ; The three laser displacement sensors can automatically measure the distance from the surface of the standard cabin model to each laser displacement sensor. This data is a known quantity, so it will not be described in detail.

[0059] S14, according to the coordinates of three laser displacement sensors , as well as and distance , as well as Calculate the coordinates of the measured points on the cabin surface , as well as ;

[0060] Specifically, the coordinates of the three laser displacement sensors , as well as It can be determined during system calibration and can be considered as a known quantity, distance , as well as are the measurement readings of the three laser displacement sensors, which are also known quantities. Substituting the known quantities into the formula, we can obtain the coordinates of the three measured points on the surface of the standard cabin model:

[0061] Coordinates of the measured points on the cabin surface for:

[0062]

[0063] Coordinates of the measured points on the cabin surface for:

[0064]

[0065] Coordinates of the measured points on the cabin surface for:

[0066]

[0067] S15, according to the coordinates of the measured points on the cabin surface , as well as Determine the center coordinates of the standard cabin model.

[0068] Specifically, the center coordinates The calculation formula is:

[0069]

[0070] like Figure 2 As shown, after determining the coordinates of three points on the surface of the standard cabin model, the diameter and center coordinates of the standard cabin model can be determined through the coordinates of the three points. The center coordinates can provide basic data for the posture of the subsequent cabin to be tested.

[0071] S2, using three laser displacement sensors to measure the distance from the surface of the test cabin to each laser displacement sensor, and determining the center coordinates of the test cabin according to the distance;

[0072] Different from the standard cabin model in step S1, when the cabin to be tested deflects due to manufacturing and pre-assembly errors, and its axis is no longer perpendicular to the plane where the laser displacement sensor is located, the coordinates of the three points detected by the laser displacement sensor will be located on the ellipse, such as Figure 3 As shown, at this time, when only considering the cross section of the cabin to be measured, the three measured points cannot determine the ellipse of the cross section of the cabin to be measured, and the intersection of its major and minor axes cannot be accurately predicted. Therefore, the posture of the cabin to be measured cannot be calculated and perceived.

[0073] It should be noted that, under the factors that cause the deflection of the cabin to be tested due to manufacturing and pre-assembly errors, this embodiment is verified by examples. The calculation problem of the center coordinates of the cabin to be tested with an elliptical cross-section is converted into the problem of solving the coordinates of the circumscribed circle determined by three points in space, thereby completing the calculation of the center coordinates of the cabin to be tested. The example verification is modeled by 3D modeling software and combined with a simplified shaft end face model measurement. The feasibility of calculating the center coordinates of the cabin to be tested is verified by comparing whether the range of the axis centerline deflection angle is within an acceptable range. The specific example verification is as follows:

[0074] Consider using 3D modeling software for modeling, combined with a simplified shaft end face model for measurement. If the deviation of the axis centerline deflection angle is small or within an acceptable range, and the spatial position of the axis centerline deflection angle of the cabin to be measured can be approximately obtained, it is preferred.

[0075] Given known conditions, for example, in a cabin, the distance between the two detection surfaces of cabin section A is 970mm, the distance between the two detection surfaces of cabin section B is 253mm, the distance between the two detection surfaces of cabin section C is 2730mm, and the diameter of the cabin is 360mm. The distance between the two detection surfaces refers to the center distance between the front end face of one cabin section and the other end face.

[0076] The corresponding parameters were input into a 3D modeling software, and the shaft end face model in the software was used to calculate that after the cabin was pre-installed, the axis centerline deflection angle range was ±5°, that is, the maximum deflection on one side was 5°. Then, a simplified model of the cabin was drawn in the 3D modeling software and deflected by 5° and 2°, and then the elliptical degree of the cabin was calculated in the 3D modeling software.

[0077] like Figure 4 As shown, when the axis line of the cabin body is deflected at an angle of 5°, the change in the cabin body cross section is as follows: since the cross section is elliptical, the length of the major axis becomes 361.375 mm, and the length of the minor axis is 360 mm.

[0078] like Figure 5 As shown, when the axis line of the cabin body is deflected at an angle of 2°, the change in the cabin body cross section is: the length of the major axis becomes 360.343 mm, and the length of the minor axis is 360 mm.

[0079] By simulating the tilt of the cabin section at two tilt angles, that is, when the cabin axis deflection angles are 5° and 2° respectively, and observing the cross section where the laser displacement sensor is located, it can be seen that the cabin has a relatively small elliptical degree, but it should be noted that when the cabin axis deflects, the translation of the cabin end surface will be magnified. Figure 6 As shown in the figure, assuming that one end face only deflects without translation, the translation of the other end face can reach:

[0080]

[0081] Where L is the distance from the rotation center to the measured section. is the deflection angle of the axis of the cabin.

[0082] For cabin section A, the most extreme displacement can reach: 970*tan(5)≈84mm. According to the case where the rotation center is located in the middle of the two sections, the deflection angle is 5°, the two ends are in opposite directions, and the amplitude is 42mm. The shape of the section before and after the change can be simplified as follows Figure 7 The situation shown in Figure 7 middle, Figure 7 The left side is the general case of axial deflection cross-section model. Figure 7 On the right is the special case model for shaft deflection.

[0083] from Figure 7 It can be simply estimated from the simplified axis deflection model shown that the axis section that is an ellipse after a 5° deflection is approximated to a perfect circle, and its axis center position deviation is about 1.4mm. After a 2° deflection, the axis center position deviation is about 0.3mm, which is estimated not to affect the docking of the cabin. Therefore, due to the complexity of the calculations involved in accurate modeling, calculation, and perception, an approximate method is proposed here to approximate the exact solution. Through example verification, it can be confirmed that the feasibility of solving three points in space to determine the coordinates of the center of the circumscribed circle can not only improve the calculation rate and reduce the amount of calculation, but also improve the accuracy of the calculation results of the center coordinates of the cabin to be tested.

[0084] Therefore, the specific process is different from the method of determining the center coordinates of the standard cabin model under ideal conditions.

[0085] like Figure 8 As shown, in step S2 of this embodiment, in order to clearly and completely illustrate the specific implementation method of step S2, the specific process of step S2 includes the following steps:

[0086] S21, let the spatial coordinates of the three points on the surface of the test cabin be , , , the coordinates of the space center C of the test cabin are , the radius of the cabin to be tested is R;

[0087] Through the above examples, it is concluded that the calculation problem of the center coordinates of the elliptical cross-section of the cabin to be tested can be converted into the problem of solving the coordinates of the center of the circumscribed circle determined by three points in space. Therefore, based on the data obtained by three laser displacement sensors, the two-dimensional coordinates of the three measured points on the surface of the cabin to be tested can be directly converted into three-dimensional coordinates in three-dimensional space, which are , , , and let the coordinates of the center C of the space be , the radius of the cabin to be tested is R.

[0088] S22. Determine three measured points , , With the center of space The plane equation of the plane;

[0089] According to the three measured points , , The coordinates of can be obtained:

[0090]

[0091] From formula (1), we can get:

[0092]

[0093] In the above formula, , , , They are:

[0094]

[0095]

[0096]

[0097]

[0098] Since the three measured points , and The distances to the center C of the space circle are equal, so:

[0099]

[0100] Then, the above three formulas are solved together to obtain:

[0101]

[0102] Denoted as:

[0103]

[0104]

[0105] Denoted as:

[0106]

[0107] Combining formulas (2), (3) and (4), we can get the plane equation:

[0108]

[0109] S23, according to the measured point , , With the center of space The plane equation of the plane is used to calculate the center coordinates of the cabin to be measured;

[0110] The calculation formula of the center coordinates of the cabin to be measured is:

[0111]

[0112] That is:

[0113]

[0114] The cross-sectional radius R of the test cabin is:

[0115]

[0116] S3, based on the central coordinates of the standard cabin model, calculating the central position deviation of the cabin to be tested relative to the standard cabin model;

[0117] In step S3, based on the central coordinates of the standard cabin model, the central position deviation of the cabin to be tested relative to the standard cabin model is calculated, which specifically includes:

[0118] According to the center coordinates of the standard cabin model and the center coordinates of the test cabin Calculate the center position deviation E;

[0119]

[0120] The center coordinates of the known standard cabin model and the center coordinates of the test cabin By calculating the difference between the two center coordinates, the center position deviation E can be obtained. According to the center position deviation E, it can be clearly understood whether the axis line of the test cabin is on the same horizontal line as the axis line of the standard cabin model. If so, there is no need to adjust the orientation of the test cabin. If not, it is necessary to adjust the orientation of the test cabin so that the axis line of the test cabin is on the same horizontal line as the axis line of the standard cabin model.

[0121] S4, determining the equation of the straight line corresponding to the axis line according to the center coordinates of the cabin to be tested;

[0122] Specifically, let the spatial center coordinates of the cross sections at both ends of the test cabin be and , then the space center coordinates and The axis line of the test cabin , and the axis The equation of the straight line is:

[0123]

[0124] S5. Adjust the orientation of the cabin to be tested according to the straight line equation corresponding to the axis center line.

[0125] Please refer to Fig. 9 In this embodiment, the state of two cabins in a three-dimensional space coordinate system is used as an example to illustrate the axis line of the cabin to be measured. The corresponding straight line equation is:

[0126]

[0127] The coordinates of the center of the space at both ends of the other cabin are and , the axis of the cabin The corresponding straight line equation is:

[0128]

[0129] Subsequently, according to specific application requirements, the orientation of the cabin can be further adjusted based on the relative positions of formulas (5) and (6) in space so that its axis lines are on the same horizontal line.

[0130] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the above embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments.

[0131] The above implementation methods have been described in detail. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for calculating the center of a cabin workpiece based on laser ranging, characterized in that: The method comprises the following steps: S1. Using a plurality of laser displacement sensors to measure the distance from the surface of the standard cabin model to each laser displacement sensor, and determining the center coordinates of the standard cabin model according to the distance; Using a plurality of laser displacement sensors to measure the distance from the surface of the standard cabin model to each laser displacement sensor, and determining the center coordinates of the standard cabin model according to the distance. The specific process includes the following steps: S11, making the central axis of the standard cabin model and the plane formed by the three laser displacement sensors perpendicular to each other; S12. With the center of the standard cabin model as the origin and the positive direction of the x-axis as the starting point, three laser displacement sensors are arranged at 0°, 180° and 270° of the standard cabin model respectively. The coordinates of the three laser displacement sensors are , as well as ; S13, obtaining the measurement data of the laser displacement sensor, then the distances from the surface of the standard cabin model to each laser displacement sensor are respectively , as well as ; S14, according to the coordinates of the three laser displacement sensors , as well as and distance , as well as Calculate the coordinates of the measured points on the cabin surface , as well as ; S15, according to the coordinates of the measured points on the cabin surface , as well as Determine the center coordinates of the standard cabin model; S2, using three laser displacement sensors to measure the distance from the surface of the cabin to be measured to each laser displacement sensor, and determining the center coordinates of the cabin to be measured according to the distance; using three laser displacement sensors to measure the distance from the surface of the cabin to be measured to each laser displacement sensor, and determining the center coordinates of the cabin to be measured according to the distance, the specific process includes the following steps: S21, let the spatial coordinates of the three points on the surface of the test cabin be , , , the coordinates of the space center C of the test cabin are , the radius of the cabin to be tested is R; S22. Determine three measured points , , With the center of space The plane equation of the plane where it is located is: ； In the above formula, , , , They are: ； ； ； ； The coordinates of the three measured points are: , , ; S23, according to the measured point , , With the center of space The plane equation of the plane is used to calculate the center coordinates of the cabin to be measured; the calculation formula for the center coordinates of the cabin to be measured is: ； In the above formula, , , , is a known quantity S3. Based on the central coordinates of the standard cabin model, the central position deviation of the cabin to be tested relative to the standard cabin model is calculated. Based on the central coordinates of the standard cabin model, the central position deviation of the cabin to be tested relative to the standard cabin model is calculated, specifically including: According to the center coordinates of the standard cabin model and the center coordinates of the test cabin Calculate the center position deviation E; S4. Determine the equation of the straight line corresponding to the axis line according to the center coordinates of the test cabin. The corresponding straight line equation is: ； In the above formula, the spatial center coordinates of the cross sections at both ends of the measuring cabin are and , then the space center coordinates and The axis line of the test cabin ; S5. Adjust the orientation of the cabin to be tested according to the straight line equation corresponding to the axis center line.

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