A raceway soft belt polishing robot based on a laser ranging sensor

Abstract

The application provides a kind of raceway soft band polishing robot tool setting method based on laser ranging sensor, including the following steps: laser ranging sensor is installed on the side of the tool of robot, the distance parameter of large bearing raceway soft band and laser ranging sensor is obtained by scanning using laser ranging sensor through the vertical movement of robot;Based on the tool coordinate system of robot and the measurement data of laser ranging sensor, the polishing area of workpiece can be positioned and the shape of raceway soft band of large bearing is obtained, the raceway soft band is fitted by using least square method, the radius and center of the circle where the raceway soft band is located are obtained, and the symmetry axis of raceway soft band profile is obtained by using minimum inertia algorithm;The Z-axis in the tool coordinate system established by robot coincides with the symmetry axis of raceway soft band profile obtained, the tool setting of robot polishing raceway soft band is realized, and the technical problems of low efficiency and low accuracy of manual tool setting of robot polishing raceway soft band are solved.

Description

Technical Field

[0001] This invention relates to the field of digital measurement technology, specifically to a tool setting method for a roller conveyor grinding robot based on a laser rangefinder sensor. Background Technology

[0002] Robots integrate advanced manufacturing technologies such as multifunctionality, multiple degrees of freedom, flexibility, and reprogrammability. They are products that combine multiple disciplines such as electrical engineering, mechanical engineering, and computer science. By designing, controlling, and optimizing the operation process, they can improve work efficiency, ensure product quality, reduce company costs, and reduce environmental pollution. They are an important manifestation of industrial automation.

[0003] In recent years, grinding has been increasingly widely used in aerospace, shipbuilding, chemical, metallurgical, transportation machinery, and various machining industries. However, with the rapid development of the manufacturing industry, customers have increasingly higher requirements for product appearance quality, and the precision requirements for grinding have become correspondingly more stringent. Currently, in the medium-frequency induction hardening process of large wind turbine bearing raceways using current methods, soft strips inevitably appear. To prevent structural failure caused by the bearing rollers bearing loads on these soft strips, grinding is necessary. In China, the grinding of soft strips on the raceways of large bearings is mostly done manually or by machine, making automated grinding difficult. Manual grinding is inefficient, has a high scrap rate, and makes it difficult to guarantee consistent grinding and polishing quality. In particular, the dust generated during grinding poses a significant health risk to operators. Machine grinding, on the other hand, is too costly for companies to accept. Therefore, robotic automated grinding has become the preferred option. To achieve robotic automated grinding, the first problem to solve is automatic tool setting in robotic grinding, in order to improve work efficiency and save labor costs.

[0004] Machine vision and laser rangefinders are two common sensing methods used in robots for mapping, localization, and obstacle detection. Due to the precision requirements of grinding processes, machine vision struggles to achieve high-precision recognition and positioning, and it is also significantly affected by environmental and working conditions, lacking stability. Furthermore, compared to metal probes, laser rangefinders offer non-contact measurement, while metal probes are contact-based. When establishing a workpiece coordinate system by measuring the bearing center, laser rangefinders are more sensitive in triggering I / O signals. Compared to metal probes, the laser rangefinder, through least-squares fitting, establishes a more accurate workpiece coordinate system. Therefore, laser rangefinders can more effectively meet the measurement and positioning requirements of robots grinding raceways and can be applied to automatic tool setting methods in robots. Summary of the Invention

[0005] The purpose of this invention is to propose a tool setting method for a robotic grinding system for raceway soft strips based on a laser rangefinder sensor. This addresses the problems in existing technologies where grinding of raceway soft strips for large bearings primarily relies on manual grinding and machine tool grinding, making it difficult to automate the process. Manual grinding is inefficient, has a high scrap rate, and struggles to guarantee consistent grinding and polishing quality. In particular, the dust generated during grinding poses a significant health hazard to operators. Meanwhile, machine tool grinding is prohibitively expensive for businesses.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A tool setting device for a roller track grinding robot based on a laser rangefinder sensor includes a laser rangefinder sensor 2 clamped on the side of an electric spindle 3, establishing a coordinate system for the laser rangefinder sensor 2, with the light from the laser rangefinder sensor and the Y-axis in the established tool coordinate system lying in the same plane; the grinding tool 5 clamped on the electric spindle 3 is an electroplated CBN tool (a tool artificially synthesized from a superhard material of cubic boron nitride) conforming to the shape of a bearing roller track. When using the laser rangefinder sensor 2 to measure the shape of the bearing roller track, the robot 1 can scan the roller track vertically downward along the Z-axis in its world coordinate system; to identify the grinding area of ​​the roller track, a magnetic block can be placed at the grinding position. When the laser rangefinder sensor 2 scans, due to the change in measurement distance, the laser rangefinder sensor 2 will trigger an I / O signal, thus allowing the robot 1 to determine the area of ​​the roller track to be ground.

[0008] A tool setting method for a roller conveyor grinding robot based on a laser rangefinder sensor includes the following steps:

[0009] Step 1: Establish the tool coordinate system of the robot grinding tool and the laser rangefinder sensor, adjust the position and attitude of the industrial robot so that the laser rangefinder sensor measures the raceway data vertically downwards and positions the bearing raceway.

[0010] Step 2: Process the measured raceway data using the least squares method to obtain the bearing raceway profile, fit the circle where the bearing raceway is located, obtain the best function match of a set of data through the sum of squares of the minimum error, calculate the radius and center of the circle, and select a suitable profiling tool.

[0011] Step 3: Select the optimal raceway profile curve from the raceway profile measured by the laser rangefinder, and use the principle of minimum inertia algorithm to obtain the axis of symmetry of the bearing raceway soft strip.

[0012] Step 4: Adjust the position and attitude of the robot, locate the bearing raceway soft strip using the laser rangefinder, and make the Z-axis of the robot tool coordinate system coincide with the axis of symmetry of the raceway soft strip contour obtained by the minimum inertia algorithm, so that the tool and the raceway soft strip are in contact, and realize the tool setting step for grinding the raceway soft strip.

[0013] Step 2 specifically includes the following:

[0014] The formula for fitting the circle containing the bearing raceway using the least squares method is as follows:

[0015] The equation of a circle is:

[0016]

[0017] Where the coordinates of the center are , radius is ;

[0018] By transforming the equation of the circle, we obtain another form.

[0019]

[0020] make , , This yields the simplified equation of the circle.

[0021]

[0022] Find the unknown parameters in the equation , , The coordinates of the center and the radius can then be obtained.

[0023] Let the point sample set of the bearing raceway be... The number of points is Distance from each point in the sample set to the center of the circle The difference between the square of the radius and the square of the radius for,

[0024]

[0025] The least squares method is used to fit a circle, such that the distance from each point in the sample set to the center of the circle is... The difference between the square of the radius and the square of the radius Sum of squares When the minimum is reached, the parameters obtained are... , , Substituting into the previous equation, we can obtain the coordinates of the center of the circle. and radius The value of .

[0026] Step 3 specifically includes the following:

[0027] The theoretical basis of the minimum inertia algorithm is that the moment of inertia of a planar axisymmetric object attains extreme values ​​along the axis of symmetry and its perpendicular direction. The algorithm steps for finding the axis of symmetry using the minimum inertia algorithm are as follows:

[0028] Let the set of points scanned by the laser rangefinder be... ;

[0029] (1) Calculate the point set ;

[0030] Given a set of points By connecting adjacent points with line segments, a curve can be obtained. Approximate representation Broken line segment Relative to a straight line Moment of inertia ,in For the first The moment of inertia of a line segment relative to a straight line; select a specific line segment and calculate its moment of inertia;

[0031]

[0032] The inertia of this broken line segment can be represented by the mass concentrated at a certain point on the line segment. inertia Equivalent;

[0033]

[0034] make ,in It can be determined By determining the sign of the symbol and solving the equation, we obtain:

[0035]

[0036] Because of the point The relative positions on a straight line do not change with the translation or rotation of the coordinate axes, therefore, according to the point set The point set can be obtained from the above formula. ;

[0037] (2) Calculate according to the formula , , , , , , ;

[0038] From point set The formula for the moment of inertia of each line segment can be obtained:

[0039]

[0040] in, That is, the length of the line segment; therefore, the moment of inertia. for:

[0041]

[0042] beg about and The extreme values, where are denoted as , , can be obtained

[0043]

[0044] Will Substitute the moment of inertia In the formula, let , ,right Taking the partial derivative yields , The value of; where is recorded , Solving for

[0045]

[0046] (3) Calculate according to the formula , , , ;

[0047] Depend on , Substitute the value into the formula available , The value of is obtained from this, thus yielding the formula for the axis of symmetry.

[0048] Preferably, the laser ranging sensor 2 measures the center distance. Within that range, its measurement range is sufficient. Its repeatability is in The reaction time of the laser rangefinder is... (Switchable), its repeatability is Temperature characteristics are .

[0049] Preferably, in step 1, the laser rangefinder 2 is clamped to the side of the electric spindle 3, and a coordinate system of the laser rangefinder 2 is established, wherein the light rays of the laser rangefinder 2 are in the same plane as the Y-axis of the established tool coordinate system.

[0050] Preferably, in step 1, in order to determine the grinding position of the raceway soft belt, a magnetic block can be placed at the grinding position. When the laser rangefinder 2 scans, the laser rangefinder 2 will trigger an I / O signal due to the change in the measurement distance, and the industrial robot 1 can thus determine the position of the grinding raceway.

[0051] Preferably, in step 2, the least squares method for fitting a circle is a statistical detection method. During the measurement process of the laser rangefinder 2, the measurement data may contain outliers due to the influence of light and other factors. Using the least squares method to fit a circle can avoid affecting the detection of the center and radius of the circle.

[0052] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0053] This invention presents a robotic tool setting method for grinding bearing raceway soft strips based on a laser rangefinder sensor. Compared with traditional manual tool setting, this method significantly improves tool setting efficiency and accuracy. The invention uses a laser rangefinder sensor to identify the grinding area of ​​the bearing raceway soft strip and measure its contour data. The collected data is then fitted to a circle using the least squares method to obtain the least squares fitted circle equation and the raceway soft strip contour shape. The minimum inertia method is used to calculate the bearing raceway soft strip contour, obtaining the axisymmetric straight line of the bearing raceway soft strip contour. The position and attitude during tool setting are determined by the axisymmetric straight line. Based on the measurement and positioning of the laser rangefinder sensor, the robotic grinding of bearing raceway soft strips is automated. Attached Figure Description

[0054] Figure 1 This is a front view of the overall structure of the present invention;

[0055] Figure 2 These are partial workpiece drawings of the present invention;

[0056] Figure 3 This is a schematic diagram of the robot laser scanning of the present invention;

[0057] Figure 4 This is a schematic diagram of the robot polishing process of the present invention;

[0058] Figure 5 This is a tool setting diagram for the present invention;

[0059] Figure 6 This is a diagram showing the axis of symmetry of the present invention;

[0060] Figure 7 This is one of the actual measured data of the raceway soft belt in the embodiments of the present invention;

[0061] Figure 8 This is the second of the actual measured data of the raceway soft belt in the embodiments of the present invention;

[0062] Figure 9 This is the third set of actual measured data for the raceway soft belt in this embodiment of the invention;

[0063] In the diagram: 1—Robot; 2—Laser rangefinder; 3—Electric spindle; 4—Workpiece; 5—Grinding tool; 6—Z-axis; 7—Y-axis. Detailed Implementation

[0064] To clarify the technical problems, technical solutions, implementation processes, and performance demonstrations, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative. The present invention is not intended to limit the scope of the invention. Various exemplary embodiments, features, and aspects of this disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the drawings denote elements with the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0065] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0066] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0067] Example 1

[0068] A tool setting device for a roller track grinding robot based on a laser rangefinder sensor includes a laser rangefinder sensor 2 clamped on the side of an electric spindle 3, establishing a coordinate system for the laser rangefinder sensor 2, with the light from the laser rangefinder sensor and the Y-axis in the established tool coordinate system lying in the same plane; the grinding tool 5 clamped on the electric spindle 3 is an electroplated CBN tool conforming to the shape of a bearing roller track. When using the laser rangefinder sensor 2 to measure the shape of the bearing roller track, the robot 1 can scan the roller track vertically downward along the Z-axis in its world coordinate system; to identify the grinding area of ​​the roller track, a magnetic block can be placed at the grinding position. When the laser rangefinder sensor 2 scans, due to the change in measurement distance, the laser rangefinder sensor 2 will trigger an I / O signal, thus allowing the robot 1 to determine the area of ​​the roller track to be ground.

[0069] Preferably, the laser ranging sensor 2 measures the center distance. Within that range, its measurement range is sufficient. Its repeatability is in The reaction time of the laser rangefinder is... (Switchable), its repeatability is Temperature characteristics are .

[0070] A tool setting method for a roller conveyor grinding robot based on a laser rangefinder sensor includes the following steps:

[0071] Step 1: Establish the tool coordinate system of the robot grinding tool and the laser rangefinder sensor, adjust the position and attitude of the industrial robot so that the laser rangefinder sensor measures the raceway data vertically downwards and positions the bearing raceway.

[0072] In step 1, the laser rangefinder 2 is clamped on the side of the electric spindle 3, and a coordinate system of the laser rangefinder 2 is established, wherein the light rays of the laser rangefinder 2 are in the same plane as the Y-axis of the established tool coordinate system.

[0073] In step 1, in order to determine the grinding position of the raceway soft belt, a magnetic block can be placed at the grinding position. When the laser rangefinder 2 scans, the laser rangefinder 2 will trigger an I / O signal due to the change in the measurement distance, and the industrial robot 1 will thus determine the position of the grinding raceway.

[0074] Step 2: Process the measured raceway data using the least squares method to obtain the bearing raceway profile, fit the circle where the bearing raceway is located, obtain the best function match of a set of data through the sum of squares of the minimum error, calculate the radius and center of the circle, and select a suitable profiling tool.

[0075] As a preferred method, the least squares method for fitting a circle is a statistical detection method. During the measurement process of the laser rangefinder 2, the measurement data may contain outliers due to the influence of light and other factors. Using the least squares method to fit a circle can avoid affecting the detection of the center and radius of the circle.

[0076] Preferably, step 2 specifically includes the following:

[0077] The formula for fitting the circle containing the bearing raceway using the least squares method is as follows:

[0078] The equation of a circle is:

[0079]

[0080] Where the coordinates of the center are , radius is ;

[0081] By transforming the equation of the circle, we obtain another form.

[0082]

[0083] make , , This yields the simplified equation of the circle.

[0084]

[0085] Find the unknown parameters in the equation , , The coordinates of the center and the radius can then be obtained.

[0086] Let the point sample set of the bearing raceway be... The number of points is Distance from each point in the sample set to the center of the circle The difference between the square of the radius and the square of the radius for,

[0087]

[0088] The least squares method is used to fit a circle, such that the distance from each point in the sample set to the center of the circle is... The difference between the square of the radius and the square of the radius Sum of squares When the minimum is reached, the parameters obtained are... , , Substitute into the previous equation The coordinates of the center of the circle can then be obtained. and radius The value of .

[0089] According to such Figures 7-9 The actual measured data of the raceway soft strip shown was obtained through MATLAB algorithm calculation. , , From this, the coordinates of the center and the radius of the circle can be calculated:

[0090]

[0091]

[0092]

[0093] Therefore, the coordinates of the center of the circle obtained by least squares fitting are: Its radius is .

[0094] Step 3: Select the optimal raceway profile curve from the raceway profile measured by the laser rangefinder, and use the principle of minimum inertia algorithm to obtain the axis of symmetry of the bearing raceway soft strip.

[0095] Preferably, step 3 specifically includes the following:

[0096] The theoretical basis of the minimum inertia algorithm is that the moment of inertia of a planar axisymmetric object attains extreme values ​​along the axis of symmetry and its perpendicular direction. The algorithm steps for finding the axis of symmetry using the minimum inertia algorithm are as follows:

[0097] Let the set of points scanned by the laser rangefinder be... ;

[0098] (6) Calculate the point set ;

[0099] Given a set of points By connecting adjacent points with line segments, a curve can be obtained. Approximate representation Broken line segment Relative to a straight line Moment of inertia ,in For the first The moment of inertia of a line segment relative to a straight line; select a specific line segment and calculate its moment of inertia;

[0100]

[0101] μ is the linear density, and the mass is assumed to be uniformly distributed, i.e., μ is a constant, and k is the slope of the straight line between the two points; the inertia of this broken line segment can be represented by the mass concentrated at a certain point on the line segment. inertia Equivalent;

[0102]

[0103] make ,in It can be determined By determining the sign of the symbol and solving the equation, we obtain:

[0104]

[0105] Because of the point The relative positions on a straight line do not change with the translation or rotation of the coordinate axes, therefore, according to the point set The point set can be obtained from the above formula. ;

[0106] (7) Calculate according to the formula , , , , , , ;

[0107] From point set The formula for the moment of inertia of each line segment can be obtained:

[0108]

[0109] in, That is, the length of the line segment; therefore, the moment of inertia. for:

[0110]

[0111] beg about and The extreme values, where are denoted as , , can be obtained

[0112]

[0113] Will Substitute the moment of inertia In the formula, let , ,right Taking the partial derivative yields , The value of; where is recorded , Solving for

[0114]

[0115] (3) Calculate according to the formula , , , ;

[0116] Depend on , Substitute the value into the formula available , The value of is obtained from this, thus yielding the formula for the axis of symmetry.

[0117] According to such Figures 7-9 The actual measured data of the raceway soft strip shown was obtained through MATLAB algorithm calculation. , The value of , one of which matches the actual image, is obtained: , .

[0118] Therefore, the axis of symmetry for the bearing raceway soft belt measurement data is... .

[0119] Step 4: Adjust the position and attitude of the robot, locate the bearing raceway soft strip using the laser rangefinder, and make the Z-axis of the robot tool coordinate system coincide with the axis of symmetry of the raceway soft strip contour obtained by the minimum inertia algorithm, so that the tool and the raceway soft strip are in contact, and realize the tool setting step for grinding the raceway soft strip.

[0120] This invention discloses a tool setting method for a robotic grinding system for bearing raceways based on a laser rangefinder sensor, solving the problem of low tool setting efficiency in robotic grinding of bearing raceways. Compared to traditional manual tool setting methods, this method significantly improves tool setting efficiency and accuracy. This invention uses a laser rangefinder sensor to identify the grinding area of ​​the bearing raceway and measure the raceway contour data. The collected data is then fitted to a circle using the least squares method to obtain the least squares fitted circle equation and the raceway contour shape. The minimum inertia method is used to calculate the bearing raceway contour, obtaining the axisymmetric straight line of the bearing raceway contour. The position and attitude during tool setting are determined by the axisymmetric straight line. Based on the measurement and positioning of the laser rangefinder sensor, the robotic grinding of bearing raceways is automated.

[0121] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A tool setting method for a roller conveyor belt grinding robot based on a laser rangefinder sensor, characterized in that, The system includes a tool setting device, a laser rangefinder (2) clamped on the side of the electric spindle (3), and a coordinate system for the laser rangefinder (2) is established. The light from the laser rangefinder is in the same plane as the Y-axis in the established tool coordinate system. The grinding tool (5) clamped on the electric spindle (3) is an electroplated CBN tool with a contoured bearing raceway shape. When the laser rangefinder (2) is used to measure the shape of the bearing raceway soft strip, the robot (1) can scan the raceway vertically downward along the Z-axis in its world coordinate system. To identify the grinding area of ​​the raceway soft strip, a magnetic block can be placed at the grinding position. When the laser rangefinder (2) sweeps across, the laser rangefinder (2) will trigger an I / O signal due to the change in the measurement distance. The robot (1) will then determine the area of ​​the raceway soft strip to be ground. The tool setting method includes the following steps: Step 1: Establish the tool coordinate system of the robot grinding tool and the laser rangefinder sensor, adjust the position and posture of the industrial robot so that the laser rangefinder sensor moves vertically downward and scans and measures the raceway data, and positions the bearing raceway. Step 2: Process the measured raceway data using the least squares method to obtain the bearing raceway profile, fit the circle where the bearing raceway is located, obtain the best function match of a set of data through the sum of squares of the minimum error, calculate the radius and center of the circle, and select a suitable profiling tool. Step 3: Select the optimal raceway profile curve from the raceway profile measured by the laser rangefinder, and use the principle of minimum inertia algorithm to obtain the axis of symmetry of the bearing raceway soft strip. Step 4: Adjust the position and attitude of the robot, use the laser rangefinder to position the bearing raceway soft strip and make the Z-axis of the robot tool coordinate system coincide with the axis of symmetry of the raceway soft strip contour obtained by the minimum inertia algorithm, so that the tool and the raceway soft strip are in contact, and realize the tool setting step for grinding the raceway soft strip. Step 2 specifically includes the following: The formula for fitting the circle containing the bearing raceway using the least squares method is as follows: The equation of a circle is: ； Where the coordinates of the center are , radius is ; By transforming the equation of the circle, we obtain another form. ； make , , This yields the simplified equation of the circle. ； Find the unknown parameters in the equation , , The coordinates of the center and the radius can then be obtained. Let the point sample set of the bearing raceway be... The number of points is Distance from each point in the sample set to the center of the circle The difference between the square of the radius and the square of the radius for, ； The least squares method is used to fit a circle, such that the distance from each point in the sample set to the center of the circle is... The difference between the square of the radius and the square of the radius Sum of squares When the minimum is reached, the parameters obtained are... , , Substitute into the previous equation The coordinates of the center of the circle can then be obtained. and radius The value; Step 3 specifically includes the following: The theoretical basis of the minimum inertia algorithm is that the moment of inertia of a planar axisymmetric object attains extreme values ​​along the axis of symmetry and its perpendicular direction. The algorithm steps for finding the axis of symmetry using the minimum inertia algorithm are as follows: Let the set of points scanned by the laser rangefinder be... ; (1) Calculate the point set ; Given a set of points By connecting adjacent points with line segments, a curve can be obtained. Approximate representation Broken line segment Relative to a straight line Moment of inertia ,in For the first The moment of inertia of a line segment relative to a straight line; select a specific line segment and calculate its moment of inertia; ； The inertia of this broken line segment can be represented by the mass concentrated at a certain point on the line segment. inertia Equivalent; ； make ,in It can be determined By determining the sign of the symbol and solving the equation, we obtain: ； Because of the point The relative positions on a straight line do not change with the translation or rotation of the coordinate axes, therefore, according to the point set The point set can be obtained from the above formula. ; (2) Calculate according to the formula , , , , , , ; From point set The formula for the moment of inertia of each line segment can be obtained: ； in, That is, the length of the line segment; therefore, the moment of inertia. for: ； beg about and The extreme values, where are denoted as , , can be obtained ； Will Substitute the moment of inertia In the formula, let , ,right Taking the partial derivative yields , The value of; where is recorded , Solving for ； (3) Calculate according to the formula , , , ; Depend on , Substitute the value into the formula available , The value of is obtained from this, thus yielding the formula for the axis of symmetry.

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