Workpiece positioning method of bearing soft belt polishing robot

Abstract

This invention discloses a workpiece positioning method for a bearing soft-strip grinding robot, belonging to the field of industrial robot technology applications. The method includes: calibrating the laser sensor signal trigger point and establishing a laser coordinate system; measuring the workpiece with the laser sensor, initially positioning the workpiece, and establishing a workpiece coordinate system; measuring the bearing end face and reference surface with the laser sensor to precisely adjust the workpiece coordinate system position; laser scanning to identify the boundary of the soft-strip grinding area and calculating the grinding area position. This method performs preliminary measurement and positioning of the workpiece by establishing a laser coordinate system, and then precisely positions the workpiece based on this. The processing area position is determined by laser scanning according to the workpiece positioning information. This solves the problem of difficult positioning and adjustment of large bearing-type workpieces by robots and improves the positioning accuracy of large bearings by robots.

Description

Technical Field

[0001] This invention relates to the field of industrial robot application technology, specifically to a workpiece positioning method for a bearing soft belt grinding robot. Background Technology

[0002] Large, heavy-duty bearings often have a soft, unhardened area on the raceway, whose overall mechanical properties are inferior to those of the hardened area. To prevent this soft area from failing under load during operation, it is generally necessary to grind it into a specific shape. When using a robot to grind the soft bearing area, the workpiece's positioning accuracy determines the grinding quality and work efficiency. Large bearings are difficult to position precisely due to their size, and this process is time-consuming. Because robots are limited by workspace and have relatively poor overall motion accuracy, positioning large workpieces using robots is even more challenging. Therefore, it is necessary to research and implement robot-based positioning of large workpieces to improve their accuracy. Summary of the Invention

[0003] To address the above problems, this invention provides a method for robot bearing positioning, which involves installing a Panasonic HG-C series or Keyence IL / LK series laser displacement sensor (hereinafter referred to as laser sensor) at the robot's end effector. The laser sensor performs non-contact measurement of the bearing, positions the bearing based on the measurement results, and scans and identifies the grinding area using the laser sensor's trigger function. This method can solve the problem of robots struggling to position large bearing-like workpieces, improve the robot's workpiece positioning accuracy, and reduce positioning time.

[0004] The technical solution of the present invention is as follows:

[0005] This invention provides a workpiece positioning method for a bearing soft-belt grinding robot. The specific steps are as follows:

[0006] Step 1: Calibrate the laser sensor signal trigger point P1 and establish the laser coordinate system {B};

[0007] Step 2: The laser sensor measures the workpiece, initially positions the workpiece, and establishes the workpiece coordinate system {C};

[0008] Step 3: The laser sensor measures the bearing end face D and the reference surface E, acquires and processes the measurement results and position information of the measurement points, and precisely adjusts the origin position of the workpiece coordinate system {C}.

[0009] Step 4: Using the signal triggering function of the laser sensor, the laser scan identifies the boundary of the soft strip grinding area, records its position information, and calculates the position of the grinding area.

[0010] In step 1, to establish the laser coordinate system {B}, the specific steps are as follows:

[0011] Step A1: Set the laser sensor signal trigger position. Set the displacement of the signal trigger point P1 to x1 within the measurement range a to b of the laser sensor. That is, when the measured displacement x ≤ x1 (or x ≥ x1), a trigger signal is output.

[0012] Step A2: Using the robot's tool coordinate system establishment function, record the position vector of point P1 in the robot's end-effector coordinate system {A}. A P1 = [ A x1, A y1, A z1] T Select a point P2 on the laser line within the measurement range of the laser sensor, and record the position vector of point P2 in the robot's end-effector coordinate system {A}. A P2 = [ A x2, A y2, A z2] T At this moment, in coordinate system {A}, the direction vector of the laser line is... A P 12 = A P2- A P1, set the laser line direction as the x-axis direction of the laser coordinate system {B}, and the rotation angle can be calculated by the following formula:

[0013]

[0014]

[0015] Where A is the rotation angle of coordinate system {B} about the z-axis of coordinate system {A}. B is the rotation angle of coordinate system {B} about the y-axis of coordinate system {A}.

[0016] When performing step 2, the specific steps are as follows:

[0017] Step B1: Determine the laser measurement range based on the workpiece specifications and approximate position information. The measurement start position is outside (or inside) the bearing, with the laser line perpendicular to the bearing end face D. The displacement L1 of the laser source from the bearing end face should be ≤ x1. The laser source gradually approaches the bearing parallel to the bearing end face. When the laser line just touches the bearing end face, a trigger signal is generated, and the robot records this position. Repeat the above operation to measure two more points, maximizing the distance between the three points. The coordinates of the center C0 in the robot's world coordinate system {W} are determined by the coordinates of the three points, assigning x0 and y0 to the center C0 in the x and y directions, respectively.

[0018] Step B2: Move the laser source above the bearing end face D, ensuring the laser line is perpendicular to the bearing end face and the distance L1 > x1. Gradually move the laser source closer to the bearing end face until the robot receives the laser trigger signal. Record the coordinates z0 of coordinate system {B} in the z-direction of coordinate system {W} at this time. The center C0(x0, y0, z0) is the origin of the workpiece coordinate system {C}, and the coordinate axes of coordinate system {C} are in the same direction as coordinate system {W}.

[0019] In step 3, the coordinates of the center C0 are precisely adjusted. The specific steps are as follows:

[0020] Step C1: Measure the reference surface E using a laser sensor. Place an object M, with a thickness of h, that can be adsorbed onto the workpiece at the starting position of the measurement, on the plane z = W z B Above, the laser line is perpendicular to the reference plane E and orbits around the bearing axis l0: A circular path measurement is performed. The distance between the laser source and the reference plane E is L2, satisfying x1 < L2 < x1 + h. When the laser touches the adsorbed object, a trigger signal is generated, and the robot records the position of that point. According to formula l c =r c θ c Determine the central angle θ corresponding to the measurement area. c , l c It is the length of the measurement area, r c This is the radius of the measurement area. Measurement information is collected from n points within the measurement area, and the central angle between adjacent measurement points is... Calculate the location information of each measurement point, perform laser measurement on the measurement point, and save and transmit the measurement results and location information of the measurement point to the host computer.

[0021] Step C2: The host computer calculates the measurement point N. i Determine the homogeneous transformation matrix of coordinate system {B} relative to coordinate system {W} based on the position information. Based on measurement point N i Measured displacement x 2i Perform the following coordinate transformations:

[0022]

[0023] in A N i =[x 2i -x1 0 0 1] T , W N i =[ W x i W y i W z i 1]T , ( W x i , W y i , W z i () is point N i Coordinates in coordinate system {W}.

[0024] By pairing n measurement points together, there are a total of Given a measurement area radius r and a set of measurement points N. i and N j (j≠i) coordinates, according to the following equation:

[0025]

[0026] Where X lim Y lim The constraints on x and y, respectively, determine the location of the center of the circle. Solve for the plane z = W z B superior Given the coordinates of the center of each circle, calculate the average of these coordinates. Adjust the C0 coordinate to

[0027] Step C3: The bearing has an inner diameter of R1 and an outer diameter of R2. Position the laser line perpendicular to the bearing end face D, with the laser line aligned with the bearing axis l1. The distance between them is R3, where R1 < R3 < R2. The laser measures the bearing end face around l1 with a radius of R3, using the same measurement method as in step C1. The measurement results are then transmitted to the host computer. n sets of e are obtained. i =x2 i -x1, calculate its mean is Then the coordinates of the origin of the workpiece coordinate system {C} are:

[0028] In step 4, the reference surface E is scanned using the workpiece coordinate system {C} as the base coordinate system, and the laser scanning method described in step C1 is used to determine the position information of the grinding area, thus completing the bearing grinding positioning.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] This invention provides a workpiece positioning method for a bearing soft belt grinding robot. It uses a laser sensor to perform non-contact measurement of the workpiece, firstly positioning the workpiece; then, fine adjustments are made based on this, and finally, the grinding area is scanned and identified. This method solves the problem of difficult positioning and adjustment of large bearing workpieces by the robot, improves the positioning accuracy of the robot for large bearings, saves time for subsequent tool setting, and provides a good foundation for robot grinding. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a robot workpiece positioning system;

[0032] Figure 2 This is a flowchart of the robot positioning process of the present invention;

[0033] Figure 3 This is a schematic diagram of the robot positioning bearing of the present invention;

[0034] Figure 4 This is a schematic diagram of the laser scanning identification and measurement area principle of the present invention. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0036] This paper describes an embodiment of installing a Panasonic HG-C series laser sensor positioning bearing inner ring using a Kuka KR210-2700 robot, and provides a detailed description of the technical solution with reference to the accompanying drawings.

[0037] like Figure 1 As shown, this invention mainly achieves workpiece positioning through a host computer, a laser sensor, and a robot. The laser sensor, robot, and host computer are connected via a switch, and Profinet / Ethernet communication is used between the host computer, robot, and laser sensor. A signal receiving end is configured between the robot and the laser sensor to realize data signal transmission between the host computer, robot, and laser sensor.

[0038] like Figures 2 to 3 As shown, the specific steps for the robot to position the inner ring of the bearing are as follows:

[0039] Step 1: Establish the laser coordinate system {B}. The specific implementation steps are as follows:

[0040] Step A1: Set the displacement of the signal trigger point P1 to x1 within the measurement range a to b of the laser sensor. When the measured value x ≤ x1, output a trigger signal.

[0041] Step A2: Select a point P2 on the light ray within the measurement range of the laser sensor. The displacement of P2 from the laser source is greater than that of P1. Fix a spherical workpiece Q within the robot's motion space and mark a point on Q. The laser sensor can accurately measure the displacement at this mark. Using the KUKA robot's four-point method, establish the origin of the tool coordinate system at points P1 and P2. That is, the robot assumes four different poses to make points P1 and P2 coincide with the marked point on Q. Record the position vectors of points P1 and P2 in the robot's end-effector coordinate system {A}. A P1 = [ A x1, A y1, A z1] T , A P2 = [ A x2, A y2, A z2] T In coordinate system {A}, the direction vector of the laser line is... A P 12 = A P2- A P1, setting the laser line direction as the x-axis direction of coordinate system {B}, the rotation angle can be calculated by the following formula:

[0042]

[0043]

[0044] Where A is the rotation angle of coordinate system {B} about the z-axis of coordinate system {A}. B is the rotation angle of coordinate system {B} about the y-axis of coordinate system {A}. Input A and B into the robot system, and set C to 0 to establish a complete coordinate system {B}, where the x-axis is along the direction of the laser line.

[0045] Step 2: The laser sensor measures the workpiece, initially positions the workpiece, and establishes the workpiece coordinate system {C}. The specific steps are as follows:

[0046] Step B1: Determine the laser measurement range based on the workpiece specifications and approximate position information. The measurement start position is outside (or inside) the bearing, with the laser line perpendicular to the bearing end face D. The displacement L1 of the laser source from the bearing end face should be ≤ x1. The laser source gradually approaches the bearing parallel to the bearing end face. When the laser line just touches the bearing end face, a trigger signal is generated, and the robot records this position. Repeat the above operation to measure two more points, maximizing the distance between the three points. The coordinates of the center C0 in the robot's world coordinate system {W} are determined by the coordinates of the three points, assigning x0 and y0 to the center C0 in the x and y directions, respectively.

[0047] Step B2: Move the laser source above the bearing end face D, ensuring the laser beam is perpendicular to the bearing end face and the distance L1 > x1. Gradually move the laser source closer to the bearing end face until the robot receives the laser trigger signal. Record the coordinates z0 of coordinate system {B} in the z-direction of coordinate system {W} at this time. The center C0(x0,y0,z0) is the origin of the workpiece coordinate system {C}. Set the rotation angles A, B, and C to 0, and the coordinate axes of coordinate system {C} are in the same direction as coordinate system {W}.

[0048] Step 3: Measure the bearing end face D and the datum surface E, acquire and process the measurement results and position information of the measurement points, and precisely adjust the origin position of the workpiece coordinate system {C}. The specific steps are as follows:

[0049] Step C1: As Figure 4 As shown, an object M with thickness h is placed at the starting position of the measurement, which can be adsorbed onto the workpiece. The object is located in the plane z = ... W z B Above, the laser line is perpendicular to the reference plane E and orbits around the bearing axis l0: A circular path measurement is performed. The distance between the laser source and the reference plane E is L2, satisfying x1 < L2 < x1 + h. When the laser touches the adsorbed object, a signal is triggered, and the robot records the position of that point. According to formula l c =r c θ c Determine the central angle θ corresponding to the measurement area. c , l c It is the length of the measurement area, r c This is the radius of the measurement area. Measurement information is collected from n points within the measurement area, and the central angle between adjacent measurement points is... Calculate the location information of each measurement point, perform laser measurement on the measurement point, and save and transmit the measurement results and location information of the measurement point to the host computer.

[0050] Step C2: The host computer calculates the measurement point N. i Determine the homogeneous transformation matrix of coordinate system {B} relative to coordinate system {W} based on the position information. Based on measurement point N i Measured displacement x 2i Perform the following coordinate transformations:

[0051]

[0052] in A N i =[x 2i -x1 0 0 1] T , W N i =[ W x i Wy i W z i 1] T , ( W x i , W y i , W z i () is point N i Coordinates in coordinate system {W}.

[0053] By pairing n measurement points together, there are a total of Given a measurement area radius r and a set of measurement points N. i and N j (j≠i) coordinates, according to the following equation:

[0054]

[0055] Where X lim Y lim The constraints on x and y, respectively, determine the coordinates of the center of the circle. Solve for the plane z = W z B On Given a set of center coordinates, calculate the average of these center coordinates. Adjust the coordinates of C0 to

[0056] Step C3: The bearing's inner diameter is R1, and its outer diameter is R2. Position the laser perpendicular to the bearing end face D, with the laser beam aligned with the bearing axis l1. The distance between them is R3, where R1 < R3 < R2. The laser measures the bearing end face around l1 with a radius of R3, using the same measurement method as in step C1. The measurement results are then transmitted to the host computer. n sets of e are obtained. i =x 2i -x1, n groups e i The mean is Then the coordinates of the origin of the workpiece coordinate system {C} are:

[0057] Step 4: Using the workpiece coordinate system {C} as the base coordinate system, scan the reference surface C1 using the laser scanning method described in step C1 above to determine the position information of the grinding area and complete the bearing grinding positioning.

[0058] This invention provides a workpiece positioning method for a bearing flexible belt robot, which improves the positioning accuracy of industrial robots for bearing parts and solves the problem of difficult positioning of large bearing parts. Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by controlling related hardware through program instructions. The above embodiments are exemplary; the measuring tool is not limited to a laser sensor, but refers to a measuring device with this function; the object of implementation is not limited to bearing parts; and the scope of implementation is not limited to bearing flexible belt grinding, and should not be construed as a limitation of this invention. Those skilled in the art can make changes, modifications, and substitutions to the above embodiments, and these should all fall within the patent coverage of this invention.

[0059] 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 present invention without departing from its novel 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 workpiece positioning method for a bearing soft-belt grinding robot, characterized in that: The workpiece is measured and positioned using a laser sensor, including Panasonic HG-C series or Keyence IL / LK series laser displacement sensors. The steps include: Step 1: Calibrate the laser sensor signal trigger point Establish a laser coordinate system {B}; Step 2: The laser sensor measures the workpiece, initially positions the workpiece, and establishes the workpiece coordinate system {C}; Step 3: The laser sensor measures the bearing end face D and the reference surface E, acquires and processes the measurement results and position information of the measurement points, and precisely adjusts the origin position of the workpiece coordinate system {C}. Step 3 includes: Step C1: Place an object M, with a thickness of h, that can be adsorbed onto the workpiece at the starting position of the measurement on the reference plane E. Above, the laser perpendicular reference plane E is positioned around the bearing axis. : Perform circular path scanning, and measure the displacement between the laser source and the reference plane E. satisfy When the laser touches the adsorbate M, a trigger signal is generated, and the robot records the position of that point; according to the formula... Determine the central angle corresponding to the measurement area. , It measures the length of the area. It is the radius of the measurement area; measurement information is collected from n points in the measurement area, and the central angle between adjacent measurement points is... The system calculates the position of each measurement point, performs laser measurement on the measurement points, saves the measurement results and position information of the measurement points, and transmits them to the host computer. Step C2: The host computer calculates the measurement points. Determine the homogeneous transformation matrix of coordinate system {B} relative to coordinate system {W} based on the position information. According to the measurement points Displacement measurement Perform the following coordinate transformations: ， in , , It is a point Coordinates in coordinate system {W}; By pairing n measurement points together, there are a total of Given a measurement area with radius r and a set of measurement points. and The coordinates are given by the following equation: ， Where X lim Y lim The constraints on x and y are respectively used to determine the position of the center of the circle; solve the plane. On Given the coordinates of the center of each circle, calculate the average of these coordinates. ,Will The coordinates are adjusted to ; Step C3: The bearing inner diameter is The outer diameter is The laser beam is perpendicular to the bearing end face D, and the laser beam is parallel to the bearing axis. : The distance between them is , Laser with radius Around Measure the bearing end face, using the same method as step C1; transmit the measurement results to the host computer; obtain n sets of data. Calculate its mean as The coordinates of the origin of the workpiece coordinate system {C} are: ; Step 4: Using the signal triggering function of the laser sensor, the laser scan identifies the boundary of the soft strip grinding area, records its position information, and calculates the position of the grinding area.

2. The workpiece positioning method of the bearing soft belt grinding robot according to claim 1, characterized in that, Step 1 includes: Step A1: Set the signal trigger point within the measurement range a~b of the laser sensor. , The displacement is When the measured value or When the time comes, output a trigger signal; Step A2: Use the robot's tool coordinate system establishment function to record points. Position vector in the robot's end-effector coordinate system {A} Select a point on the laser line within the measurement range of the laser sensor. Recording point Position vector in the robot's end-effector coordinate system {A} In coordinate system {A}, the direction vector of the laser line is... Setting the laser line direction as the x-axis of the laser coordinate system {B}, the rotation angle can be calculated using the following formula: ， ， Where A is the rotation angle of coordinate system {B} about the z-axis of coordinate system {A}. B is the rotation angle of coordinate system {B} about the y-axis of coordinate system {A}. .

3. The workpiece positioning method of the bearing soft belt grinding robot as described in claim 1, characterized in that, Step 2 includes: Step B1: The starting position for laser measurement is either outside or inside the bearing. The laser line is perpendicular to the bearing end face D. The displacement of the laser source from the bearing end face... The laser source is gradually brought closer to the bearing, parallel to the bearing end face. A trigger signal is generated when the laser line just touches the bearing end face, and the robot records this position. Then, two more points are measured, with the distance between the three points being as large as possible. The center of the bearing end face is determined from the coordinates of these three points. The coordinates in the x and y directions of the robot world coordinate system {W} are respectively and ; Step B2: Move the laser source above the bearing end face D, with the laser line perpendicular to the bearing end face. The laser source gradually approaches the bearing end face perpendicularly until the robot receives the laser trigger signal. The coordinates of coordinate system {B} in the z-direction of coordinate system {W} at this point are recorded. center That is, the origin of the workpiece coordinate system {C}, and the coordinate axes of coordinate system {C} are in the same direction as coordinate system {W}.

4. The workpiece positioning method of the bearing soft belt grinding robot according to claim 1, characterized in that, In step 4, the workpiece coordinate system {C} is used as the base coordinate system, and the reference surface E is scanned using the laser scanning method described in step C1 above to determine the position of the grinding area and complete the bearing grinding positioning.

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