Simple and convenient robot hand-eye calibration system and calibration method

Abstract

The present invention provides a simple and convenient robot hand-eye calibration system, which is suitable for industrial robots and includes: a three-dimensional scanning device, a standard part, a probe, a robot teaching pendant, and a measurement processor; the robot teaching pendant is used to control the industrial robot; one end of the probe is connected to the end of the mechanical arm of the industrial robot, and the needle tip at the other end is a free end; the three-dimensional scanning device is connected to the measurement processor, and the three-dimensional scanning device is used to scan the standard part to obtain corresponding three-dimensional point cloud data; the measurement processor and the robot teaching pendant can communicate; the standard part is set at a position that the probe can touch and the three-dimensional scanning device can scan; the standard part has at least one vertex and two vertical edges extending from the vertex, which are used to establish the workpiece coordinate system of the standard part under the robot base coordinate system. The present invention also proposes a simple and convenient robot hand-eye calibration method. The present invention is simple to operate and has high accuracy.

Description

Technical Field

[0001] The invention belongs to the field of industrial robot calibration, and in particular relates to a simple and convenient robot hand-eye calibration system and calibration method. Background Art

[0002] Industrial robots, as a kind of artificial replacement intelligent equipment, have been increasingly applied to various industries. In order to make robots play a greater role in production, it has become inevitable to equip robots with "a pair of eyes" on the road to intelligentization. However, robots are not "aware" of the existence of these "eyes", so human intervention is needed to "match" them. However, many current hand-eye calibration technologies have the problems of complex calculation principles, cumbersome operation processes, and high time costs. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a simple and convenient robot hand-eye calibration system and a corresponding calibration method; the system is simple to operate and has high precision, and solves the problems of complex calculation principles, cumbersome operation process and high time cost in the prior art. The technical solution adopted by the present invention is:

[0004] The embodiment of the present invention provides a simple and convenient robot hand-eye calibration system, which is applicable to an industrial robot. The industrial robot includes a robot base and a mechanical arm mounted on the robot base; and includes: a three-dimensional scanning device, a standard part, a probe, a robot teaching pendant, and a measurement processor;

[0005] Robot teaching pendant is used for the control of industrial robots;

[0006] One end of the probe is connected to the end of the mechanical arm of the industrial robot, and the tip of the other end is a free end; the three-dimensional scanning device is connected to the measurement processor, and the three-dimensional scanning device is used to scan the standard part to obtain the corresponding three-dimensional point cloud data; the measurement processor can communicate with the robot teaching pendant;

[0007] The standard part is arranged at a position that can be touched by a probe and scanned by a three-dimensional scanning device;

[0008] The standard part has at least one vertex and two vertical edges extending from the vertex, which are used to establish a workpiece coordinate system of the standard part in the robot base coordinate system.

[0009] Furthermore, the standard part adopts a cube or a cuboid.

[0010] Furthermore, the three-dimensional scanning device is a surface structured light scanner, or a line structured light scanner and a matching servo drive module.

[0011] Furthermore, the surface structured light scanner includes a monocular surface structured light scanner, a binocular surface structured light scanner or a multi-eye surface structured light scanner.

[0012] Furthermore, the line structured light scanner includes a single-line structured light scanner, a multi-line structured light scanner, a monocular line structured light scanner, a binocular line structured light scanner or a multi-eye line structured light scanner.

[0013] Furthermore, the mechanical arm of the industrial robot has multiple degrees of freedom, including up, down, left, right, front and back.

[0014] The embodiment of the present invention further provides a simple and convenient robot hand-eye calibration method, which is applicable to the above-mentioned robot hand-eye calibration system, including:

[0015] Step S10, setting a digital model and a digital model coordinate system of the standard part in the measurement processor, wherein the digital model of the standard part has at least one vertex and two vertical edges extending from the vertex; the digital model coordinate system takes a vertex on the standard part as an origin, takes two vertical edges extending from the vertex as X and Y axes, and takes a straight line passing through the origin and perpendicular to a plane constructed by the X and Y axes as a Z axis;

[0016] Step S20, a robot base coordinate system is provided on the robot teach pendant; a tool coordinate system corresponding to the end of the robot arm is established on the robot teach pendant; then the robot arm is controlled to drive the probe to move so that the tip of the probe contacts the vertex on the standard part that serves as the origin of the digital model coordinate system, and a workpiece coordinate system with the tip of the probe as the origin is established on the robot teach pendant, and the workpiece coordinate system is consistent with the digital model coordinate system of the standard part;

[0017] Step S30, performing rough matching, the 3D scanning device scans the 3D point cloud data of several feature points on the standard part, and the measurement processor matches the obtained 3D point cloud data of the several feature points with the position data of relevant points in the digital model of the standard part to obtain a matching matrix;

[0018] Step S40, then perform precise matching, the 3D scanning device scans the standard part, the measurement processor matches the 3D point cloud data of the remaining feature points obtained by the scan with the position data of the relevant points in the digital model of the standard part, and the matching matrix optimized by precise matching is used as the hand-eye matrix.

[0019] Furthermore, the measurement processor also performs a verification process. In the three-dimensional point cloud data obtained by scanning the standard part with the three-dimensional scanning device, the coordinate p1 of the vertex in contact with the needle tip is taken, and the hand-eye matrix is ​​multiplied on the right to obtain the coordinate p2; the coordinate p3 of the needle tip in the workpiece coordinate system when the probe needle tip contacts the vertex is obtained through the robot teaching device, and the absolute deviation delta between p2 and p3 is calculated; if delta is less than the set error value, the calibration ends; otherwise, the steps of the calibration method are repeated, and the parameters of the three-dimensional scanning device are adjusted.

[0020] Furthermore, the several feature points are four vertices among eight vertices on the cube.

[0021] The advantages of the present invention are:

[0022] 1) The robot hand-eye calibration system and calibration method proposed in the present invention have short operation steps, simple operation process, and low requirements on workers' skills and quality. They can well meet the needs of occasions where the requirements on the hand-eye calibration accuracy are not very strict and the production rhythm is fast.

[0023] 2) The robot hand-eye calibration system and calibration method proposed in the present invention have a short coordinate system conversion dimension chain, reduce error sources, and improve the hand-eye calibration accuracy.

[0024] 3) The robot hand-eye calibration system and calibration method proposed in the present invention adopts three-dimensional point cloud matching processing, which has a simple principle and high calculation accuracy, and can improve the hand-eye calibration accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the calibration system composition of the present invention. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific drawings and embodiments.

[0027] The embodiment of the present invention firstly proposes a simple and convenient robot hand-eye calibration system, which is applicable to an industrial robot 1, such as Figure 1 As shown, it includes: a three-dimensional scanning device 2, a standard part 3, a probe 4, a robot teaching device 5, and a measurement processor 6;

[0028] The industrial robot 1 includes a robot base 101 and a robot arm 102 mounted on the robot base 101; a robot teaching device 5 is used for controlling the industrial robot 1;

[0029] One end of the probe 4 is connected to the end of the mechanical arm 102 of the industrial robot 1, and the tip of the other end is a free end; the three-dimensional scanning device 2 is connected to the measurement processor 6, and the three-dimensional scanning device 2 is used to scan the standard part 3 to obtain the corresponding three-dimensional point cloud data; the measurement processor 6 can communicate with the robot teaching device 5;

[0030] The standard part 3 is arranged at a position that can be touched by the probe 4 and scanned by the three-dimensional scanning device 2; for example, the standard part 3 is arranged between the probe 4 and the three-dimensional scanning device 2, and is located below the probe 4 and the three-dimensional scanning device 2;

[0031] The standard part 3 has at least one vertex and two vertical edges extending from the vertex, which are used to establish the workpiece coordinate system of the standard part 3 in the robot base coordinate system; in this embodiment, the standard part 3 is a cube; it can also be a cuboid;

[0032] In some embodiments, the three-dimensional scanning device 2 may be a surface structured light scanner, or a line structured light scanner and a matching servo drive module;

[0033] The surface structured light scanner includes a monocular surface structured light scanner, a binocular surface structured light scanner or a multi-eye surface structured light scanner;

[0034] The line structured light scanner includes a single-line structured light scanner, a multi-line structured light scanner, a monocular line structured light scanner, a binocular line structured light scanner or a multi-eye line structured light scanner;

[0035] The mechanical arm 102 of the industrial robot 1 has multiple degrees of freedom, including up, down, left, right, front, and back;

[0036] The embodiment of the present invention also provides a simple and convenient robot hand-eye calibration method, comprising the following steps:

[0037] Step S10, setting a digital model and a digital model coordinate system of the standard part 3 in the measurement processor 6, wherein the digital model of the standard part 3 has at least one vertex and two vertical edges extending from the vertex; the digital model coordinate system takes a vertex on the standard part as the origin, the two vertical edges extending from the vertex as the X and Y axes, and a straight line passing through the origin and perpendicular to a plane constructed by the X and Y axes as the Z axis;

[0038] In some embodiments, the digital model of the standard part 3 can be established in the measurement processor 6, or can be established on other computing devices and then imported into the measurement processor 6; after the digital model of the standard part 3 is established, the standard part 3 can be obtained by processing with a finishing device; and then the standard part 3 is set at a position that can be touched by the probe 4 and scanned by the three-dimensional scanning device 2;

[0039] Step S20: a robot base coordinate system is provided on the robot teaching pendant 5; a tool coordinate system corresponding to the end of the robot arm is established on the robot teaching pendant 5; the robot arm is then controlled to drive the probe 4 to move so that the tip of the probe 4 contacts the vertex on the standard part 3 which is the origin of the digital model coordinate system, and a workpiece coordinate system with the tip of the probe as the origin is established on the robot teaching pendant 5, and the workpiece coordinate system is consistent with the digital model coordinate system of the standard part;

[0040] Since the size of the robot arm is known, the conversion relationship between the robot base coordinate system and the tool coordinate system can be determined; since the size of the probe is known, the coordinate transformation matrix between the tool coordinate system on the robot teaching pendant 5 and the established workpiece coordinate system can be determined;

[0041] Step S30, performing rough matching, the three-dimensional scanning device 2 scans the three-dimensional point cloud data of several feature points on the standard part 3, and the measurement processor 6 matches the obtained three-dimensional point cloud data of the several feature points with the position data of the relevant points in the digital model of the standard part to obtain a matching matrix; the several feature points may be four vertices among the eight vertices on the cube;

[0042] Step S40, then perform fine matching, the three-dimensional scanning device 2 scans the standard part 3, the measurement processor 6 matches the three-dimensional point cloud data of the remaining feature points obtained by scanning with the position data of the relevant points in the digital model of the standard part, and the matching matrix after the fine matching optimization is used as the hand-eye matrix; during the fine matching optimization, the upper limit of the number of iterations can be increased and the convergence value can be reduced to further improve the result accuracy;

[0043] After obtaining the hand-eye matrix, the coordinate transformation relationship between the industrial robot's "hand" - the robotic arm and the "eye" - the 3D scanning device can be determined;

[0044] Finally, the measurement processor 6 can also perform a verification process. In the three-dimensional point cloud data obtained by scanning the standard part 3 with the three-dimensional scanning device 2, the coordinate p1 of the vertex in contact with the needle tip is taken, and the hand-eye matrix is ​​multiplied on the right to obtain the coordinate p2; when the probe needle tip contacts the vertex, the coordinate p3 of the needle tip (or the vertex in contact with the needle tip) in the workpiece coordinate system is obtained through the robot teaching device 5, and the measurement processor 6 calculates the absolute deviation delta between p2 and p3; if delta is less than the set error value, the calibration ends; if delta is greater than the set error value, the requirements cannot be met, and the above steps can be repeated, as well as the parameters of the three-dimensional scanning device to improve the scanning quality. The error of every detail in the establishment process of the tool coordinate system and the workpiece coordinate system can also be controlled to improve the final calibration accuracy.

[0045] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A simple and convenient robot hand-eye calibration method, which is based on a simple and convenient robot hand-eye calibration system, wherein the calibration system is applicable to an industrial robot (1), wherein the industrial robot (1) comprises a robot base (101) and a robot arm (102) mounted on the robot base (101); characterized in that: The calibration system comprises: a three-dimensional scanning device (2), a standard part (3), a probe (4), a robot teaching device (5), and a measurement processor (6); A robot teaching device (5) is used for controlling an industrial robot (1); One end of the probe (4) is connected to the end of the mechanical arm (102) of the industrial robot (1), and the tip of the probe at the other end is a free end; the three-dimensional scanning device (2) is connected to the measurement processor (6), and the three-dimensional scanning device (2) is used to scan the standard part (3) to obtain corresponding three-dimensional point cloud data; the measurement processor (6) can communicate with the robot teaching device (5); The standard part (3) is in the form of a cube and is arranged at a position that can be touched by the probe (4) and scanned by the three-dimensional scanning device (2). The three-dimensional scanning device (2) is a surface structured light scanner or a line structured light scanner and a matching servo drive module. The surface structured light scanner comprises a monocular surface structured light scanner or a multi-eye surface structured light scanner; The line structured light scanner includes a single-line structured light scanner or a multi-line structured light scanner; The standard part (3) has at least one vertex and two vertical edges extending from the vertex, which are used to establish a workpiece coordinate system of the standard part (3) in the robot base coordinate system; The mechanical arm (102) of the industrial robot (1) has multiple degrees of freedom, including up, down, left, right, forward and backward. This simple and convenient robot hand-eye calibration method includes the following steps: Step S10, setting a digital model and a digital model coordinate system of the standard part (3) in the measurement processor (6), wherein the digital model of the standard part has at least one vertex and two vertical edges extending from the vertex; the digital model coordinate system takes a vertex on the standard part as an origin, the two vertical edges extending from the vertex as X and Y axes, and a straight line passing through the origin and perpendicular to a plane constructed by the X and Y axes as a Z axis; Step S20: a robot base coordinate system is provided on the robot teaching pendant (5); a tool coordinate system corresponding to the end of the robot arm is established on the robot teaching pendant (5); the robot arm is then controlled to drive the probe (4) to move so that the tip of the probe (4) contacts the vertex on the standard part (3) which is the origin of the digital model coordinate system, and a workpiece coordinate system with the tip of the probe as the origin is established on the robot teaching pendant (5), and the workpiece coordinate system is consistent with the digital model coordinate system of the standard part; Step S30, performing rough matching, the three-dimensional scanning device (2) scans the three-dimensional point cloud data of several characteristic points on the standard part (3), and the measurement processor (6) matches the obtained three-dimensional point cloud data of the several characteristic points with the position data of the relevant points in the digital model of the standard part to obtain a matching matrix; Step S40, then perform precise matching, the three-dimensional scanning device (2) scans the standard part (3), the measurement processor (6) matches the three-dimensional point cloud data of the remaining feature points obtained by the scan with the position data of the relevant points in the digital model of the standard part, and the matching matrix optimized by precise matching is used as the hand-eye matrix.

2. The simple and convenient robot hand-eye calibration method as claimed in claim 1, characterized in that: The measurement processor (6) also performs a verification process. In the three-dimensional point cloud data obtained by scanning the standard part (3) with the three-dimensional scanning device (2), the coordinate p1 of the vertex in contact with the needle tip is taken, and the hand-eye matrix is ​​multiplied on the right to obtain the coordinate p2; the coordinate p3 of the needle tip in the workpiece coordinate system when the probe needle tip contacts the vertex is obtained through the robot teaching device (5), and the absolute deviation delta between p2 and p3 is calculated; if delta is less than the set error value, the calibration is terminated; otherwise, the steps of the calibration method are repeated, and the parameters of the three-dimensional scanning device are adjusted.

3. The simple and convenient robot hand-eye calibration method as claimed in claim 1, characterized in that: The plurality of characteristic points are four vertices among eight vertices on the cube.

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