TWI617405B - Correction method for robot arm correction system - Google Patents

Abstract

A method for correcting a mechanical arm correction system, the robot arm correction system comprising a robot arm, a camera and a correction member, the camera having a field of view, the correction member having a correction mark; the correction method comprising: controlling a mechanical arm grasping correction And moving, driving the calibration mark of the correcting member to coincide with the reference mark in the field of view, and recording the coordinate of the robot arm as the first coordinate; controlling the rotation of the mechanical arm, driving the correcting member to rotate a predetermined angle on a correction plane, and controlling the The movement of the robot arm causes the calibration mark of the correction component to coincide with the reference mark in the field of view, and records the coordinate of the robot arm as the second coordinate, and calculates the rotation axis of the robot arm on the correction plane according to the first coordinate and the second coordinate Heart, according to the completion of the correction of the robot arm.

Description

Correction method for robot arm correction system

The present invention relates to a calibration method; in particular, to a method of correcting a mechanical arm correction system.

With the advancement of technology, the use of robotic arms to achieve automated production, assembly and other processes has been widely seen in today's production lines. Among them, since the mechanical coordinate system used for manipulating the robot arm is different from the image coordinate system of the image taken by the camera, if the robot arm is to be used for automatic production and assembly, the mechanical coordinate system of the robot arm must be used first. The image coordinates of the camera are appropriately converted, ie, the correction of the robot arm.

Please refer to FIG. 1 for one of the common correction methods in the industry. The correction method is as follows: a correction point 1a is marked at the center of the jaw of the robot arm 1, and then moved in the field of view 2 of the camera. The robot arm 1 marks three movement points trajectories 3a, 3b, and 3c corresponding to the movement trajectory of the correction point 1a of the robot arm 1 in the image taken by the camera; and thereafter, the marker points 3a to 3c The rotation axis of the robot arm 1 is calculated to achieve correction of the robot arm.

However, when the robot arm to be corrected is relatively large, please refer to FIG. 2, which is limited by the limited range of the camera's field of view 4, and the range of the swing of the robot arm 5 cannot exceed the field of view range 4 when correcting, therefore, When the robot arm 5 is corrected, the robot arm 5 can swing to a small extent, so that the rotation axis of the robot arm 5 calculated by the marked points 6a to 6c obtained is less accurate, that is, The robot arm 5 actually rotates the axis There will be considerable errors. Furthermore, when the robot arm is relatively large, when it is to be corrected by the conventional robot arm correction method, since the movable space required for the robot arm is large, it is unfavorable for the case where the space is narrow. ongoing.

In other words, the conventional method of manipulating the arm still has a lot of inconveniences and areas for improvement.

In view of the above, an object of the present invention is to provide a method for correcting a mechanical arm correction system that can accurately and quickly correct a robot arm.

In order to achieve the above object, the present invention provides a method for correcting a mechanical arm correction system, the robot arm correction system comprising a mechanical arm, a camera and a correction member, wherein the camera has a field of view, the correction member has a Correction mark; the correction method comprises the following steps: A, controlling the robot arm to grasp the correction component; B, controlling the movement of the robot arm, driving the correction component to move into the field of view of the camera, and making the correction component The calibration mark coincides with a reference mark in the field of view; C, in the recording step B, the coordinate of the robot arm on the coordinate system of the robot arm is a first coordinate; D, controlling the rotation of the mechanical arm, and driving the correction component to Rotating a predetermined angle on a correction plane; E, controlling the movement of the robot arm, causing the correction member to move into the field of view of the camera, and causing the correction mark of the correction member to coincide with the reference mark in the field of view; Recording the coordinate of the robot arm on the coordinate system of the robot arm in step E as a second coordinate; G, according to the A second coordinate scale and calculates the rotation axis of the robot on the calibration plane.

The effect of the invention is to control the mechanical arm to grasp the correction member, align the correction mark and the reference mark in the field of view, and control the rotation of the mechanical arm to drive the school. The positive member rotates on a correction plane, and the correction mark of the correcting member is again brought into coincidence with the reference mark, so that the rotation axis of the robot arm on the correction plane can be quickly and efficiently obtained.

1‧‧‧ Robotic arm

1a‧‧‧ calibration point

2‧‧‧ Field of view

3a, 3b, 3c‧‧‧ points

4‧‧‧ Field of view

5‧‧‧ Robotic arm

6a, 6b, 6c‧‧‧ points

〔this invention〕

100‧‧‧Machine Correction System

10‧‧‧ Pedestal

20‧‧‧ Robotic arm

22‧‧‧ first end

24‧‧‧ second end

26‧‧‧claw

30‧‧‧ camera

32‧‧‧ Field of view

34‧‧‧ reference mark

40‧‧‧ calibration platform

50‧‧‧Central computer

60‧‧‧calibration

62‧‧‧correction mark

Figure 1 is a schematic illustration of a conventional correction robotic arm.

2 is a schematic view of a conventional correction robot.

3 is a block diagram of a robotic arm correction system in accordance with a preferred embodiment of the present invention.

4 to 7 are schematic views showing a method of correcting the above preferred embodiment of the present invention.

In order to explain the present invention more clearly, a preferred embodiment will be described in detail with reference to the drawings. Referring to FIG. 3, which is a basic structural diagram of a robotic arm calibration system 100 to which a preferred embodiment of the present invention is applied, the robotic arm calibration system 100 includes a base 10, a robot arm 20, a camera 30, and a camera. The calibration platform 40, a central control computer 50 and a calibration component 60 (shown in Figure 4).

The robot arm 20 is a multi-axis, multi-joint robot arm. In this embodiment, a six-axis robot arm is provided. The robot arm 20 has a first end 22 and a second end 24, and the first end 22 thereof. Attached to the base 10, the second end 24 is a free end and has a jaw 26 (referenced in Figure 4) for grasping the workpiece. The robot arm 20 is connected and/or electrically connected to the central control computer 50 signal, and is controlled by the central control computer 50 to be actuated according to a mechanical arm coordinate system. Wherein, the mechanical arm coordinate system may be a coordinate system such as a right angle coordinate type, a cylindrical coordinate type, a polar coordinate type, etc., for convenience of description, in this embodiment, For example, a right-angled mechanical arm coordinate system is used. In addition, in other practical implementations, the robot arm 20 is not limited to a six-axis robot arm, and may be a three-axis, four-axis or four-axis robot arm.

The camera 30 can be disposed on a carrier (not shown) and can be controlled to adjust its photographing angle and photographing range (or field of view). For example, in the embodiment, the camera 30 is connected to and/or electrically connected to the central control computer 50, and can be adjusted by the control of the central control computer 50, or can be adjusted. In the optical axis direction, for example, in the embodiment, the optical axis of the camera 30 is perpendicular to the plane of the calibration platform 40, and the camera 30 is photographed for the plane. A field of view 32 is defined on the plane (as shown in Figure 4). Wherein, in the embodiment, the plane of the correction platform 40 is parallel to the XY plane in the world coordinate system, and the optical axis of the camera 30 is parallel to the Z axis in the world coordinate system, and perpendicular to the The XY plane is used to correct the rotation axis of the robot arm 20 about the rotation axis parallel to the Z axis, but in other embodiments, it is not limited thereto.

The calibration platform 40 is mainly used to provide a background of low noise for the camera 30 to perform shooting. In other practical implementations, the calibration platform 40 is not a necessary component.

The central control computer 50 is mainly used to control the movement of the robot arm 20 and the camera 30, that is, the robot arm 20 is controlled to move in the world coordinate system according to the mechanical arm coordinate system, and the feedback signal of the robot arm 20 can be received. (eg, touch feedback, pressure feedback signal, etc.); and can receive images in the field of view 32 captured by the camera 30 for processing, for example, based on the field of view 32 to establish a corresponding camera image coordinate system.

An embodiment of the method for correcting the robot arm system of the present invention will be described later. Referring to FIG. 4, first, step A: controlling the robot arm through the central control computer 50. The jaws 26 of the 20 grip the correcting member 60. The correction member 60 has a correction mark 62 for calibration. For example, in the embodiment, the correction member 60 is exemplified by a substantially flat object, and the correction mark 62 is set. The correction mark 62 is a circle, but the correction mark 62 is a circle, but in other embodiments, it is not limited thereto. In addition, in the embodiment, the jaws 26 of the robot arm 20 grasp an edge position of the correcting member 60 and are relatively far from the position of the correction mark 62, so that when the correction is performed, the machine The arm 20 does not block the image taking path of the camera 30 to prevent the camera 30 from effectively capturing the correction mark 62, so that the position of the correction mark 62 cannot be effectively recognized.

Next, step B: controlling the movement of the robot arm 20, and driving the correcting member 60 to move into the field of view 32 of the camera 30, and causing the correction mark 62 of the correcting member 60 and a reference mark 34 in the field of view range 32. coincide. The reference mark 34 refers to a mark for alignment and calibration of the calibration mark 62 of the correcting member 60, which can be freely selected by the user through the central control computer 50 on the image coordinate system of the camera 30, in other words. The reference mark 34 can be a particular point or block on the field of view 32 or based on a particular coordinate on its image coordinate system.

In the present embodiment, the reference mark 34 is located at the center of the photographing range 32 of the camera 30, that is, at the position of the optical axis close to the camera 30, wherein the selection is marked in the photographing center. The reference mark 34 has an advantage in that the error of the aberration caused by the image taken by the camera 30 near the optical axis is the lowest, so that a more accurate correction result can be obtained. In addition, in an embodiment, in order to further improve the accuracy of the correction, in step B, the robot arm 20 is further controlled to rotate, so that the correcting member 60 has the plane of the correction mark 62 and the camera 30. The optical axis is vertical, or the correcting member 60 has the plane of the correction mark 62 and the field of view 32 The planes are parallel, whereby the camera 30 can capture the correction mark 62 more accurately and correctly, and facilitate alignment and re-engagement between the mark 62 and the reference mark 34.

Then, after the calibration mark 62 of the correcting member 60 is overlapped with the reference mark 34, step C is performed: in the foregoing step B, the coordinate of the robot arm 20 on the coordinate system of the robot arm is a first coordinate. For example, in the present embodiment, the coordinates of the robot arm 20 are captured by the central control computer 50 and recorded as the first coordinate (X ₁ , Y ₁ , Z ₁ , Rx ₁ , Ry ₁ , Rz ₁ ) (or The first value).

Next, step D is performed: controlling the rotation of the robot arm 20 to drive the correcting member 60 to rotate by a predetermined angle on a correction plane. For example, in the embodiment, the correction plane is determined according to the rotation axis of the robot arm 20 to be corrected. For example, in the embodiment, the Z-axis rotation axis of the robot arm is performed. Correction, therefore, the correction plane is exemplified by the XY plane in the world coordinate system. In addition, in the embodiment, preferably, the predetermined angle is 180 degrees, as shown in FIG. 6, the robot arm 20 is controlled to rotate, and the correcting member 60 is rotated 180 degrees on the correction plane. In the figure, at this time, the correction mark 62 of the correcting member 60 is deviated from the reference mark 34.

Next, as shown in FIG. 7, step E is performed to control the movement of the robot arm 20 to move the correcting member 60 into the field of view 32 of the camera 30, and the correction mark 62 and the field of view range 32 of the correcting member 60 are made. The reference mark 34 in the coincidence.

Then, after the calibration mark 62 of the correcting member 60 coincides with the reference mark 34, step F is performed: in the foregoing step E, the coordinate of the robot arm 20 on the coordinate system of the robot arm is a second coordinate. For example, in the present embodiment, the coordinates of the robot arm 20 are captured by the central control computer 50 and recorded as the second coordinates (X ₂ , Y ₂ , Z ₂ , Rx ₂ , Ry ₂ , Rz ₂ ) (or Second coordinate value).

Finally, step G is performed: calculating the rotation axis of the robot arm 20 on the correction plane according to the first coordinate and the second coordinate. For example, in the present embodiment, since the correction plane corrected by the robot arm 20 is an XY plane, and the rotation axis of the robot arm 20 is rotated in the step D, the rotation axis is parallel to the Z axis, so that the robot arm 20 thereof The coordinate system of the rotating axis rotating on the XY plane is first coordinate (X ₁ , Y ₁ , Z ₁ , Rx ₁ , Ry ₁ , Rz ₁ ) and second coordinate (X ₂ , Y ₂ , Z ₂ , Rx ₂ , Ry ₂ , Rz ₂ ) are collinear, and the coordinate of the rotation axis is the midpoint of the first coordinate and the second coordinate, that is, the rotation axis can be obtained in the XY plane or along the Z axis The rotation axis of the rotation axis is ( ). Thereby, through the correction method of the robot arm system of the present invention, the rotating shaft center of the robot arm 20 rotating on a specific plane (such as the XY plane in the embodiment) can be quickly and efficiently found, thereby completing the robot arm. Correction.

It is worth mentioning that, in other practical implementations, if the rotation axis of the robot arm 20 is rotated on other planes, for example, the rotation of the robot arm 20 with the rotation axis parallel to the X (Y) axis is performed. For the correction of the axis, the optical axis of the camera 30 can be adjusted parallel to the X(Y) axis of the world coordinate system, and the plane of the correction platform 40 can be adjusted parallel to the YZ (XZ) plane in the world coordinate system, and YZ (XZ) The plane is corrected as the correction plane in the correction method of the present invention, and the rotational axis coordinates of the robot arm 20 rotating on the YZ (XZ) plane can also be obtained quickly and accurately. In addition, in the foregoing step of rotating the correction member on a correction plane by a predetermined angle, the predetermined angle is not limited to 180 degrees, and in one embodiment, may be 30 degrees, 60 degrees, or 90 degrees, and the like. The angle is taken as the predetermined angle, and the robot arm is corrected accordingly. In addition, when a predetermined angle other than 180 degrees is selected, the first coordinate and the second coordinate are regarded as the end coordinates of the two base angles of the isosceles triangle, and the predetermined angle is the vertex angle of the isosceles triangle (the inner angle of the apex), whereby the vertex coordinates of the isosceles triangle can be obtained after the end coordinates and the apex angle of the two bottom corners of the isosceles triangle are obtained, and the vertex coordinates are the robot arms parallel to The axis of rotation of the plane of the isosceles triangle is coordinate.

It is to be noted that the correction method of the conventional robot arm is mostly based on the end point of the robot arm itself (similar to the second end in this embodiment) as a correction mark for the camera to move when the robot arm moves and rotates, however, In the above manner, when the robot arm rotates, the robot arm itself easily blocks the correction mark set on itself, so that the camera cannot effectively recognize and track the position of the correction mark. In contrast, the calibration method of the present invention is that the mechanical arm additionally grabs a correction member provided with a correction mark, and therefore, the correction member protrudes from the robot arm in a plurality of directions and angles of view, and is not easily grasped by the robot arm. Because it is shielded, it is less likely to cause the camera to be unable to track and recognize the correction mark when performing the correction, and has the advantage of less restriction of the correction condition.

The above description is only a preferred embodiment of the present invention. The method for correcting the mechanical arm system of the present invention is not limited to the correction of the rotational axis only for the robot arm rotating on the XY, YZ, and XZ planes, and other practicalities. The equivalents of the present invention and the scope of the patent application are intended to be included in the scope of the invention.

Claims (7)

A method for correcting a mechanical arm correction system, the robot arm correction system comprising a mechanical arm, a camera, and a correction member, wherein the camera has a field of view, the correction member has a correction mark; and the correction method comprises the following steps : A, controlling the robot arm to grasp the correcting member; B, controlling the movement of the robot arm, driving the correcting member to move into the field of view of the camera, and making the correction mark of the correcting member and a reference in the field of view Marking coincidence; C, recording the coordinate of the robot arm on the coordinate system of the robot arm in step B as a first coordinate; D, controlling the rotation of the mechanical arm, driving the correcting member to rotate a predetermined angle on a correction plane, and Deviating the calibration mark from the reference mark; E, controlling the movement of the robot arm, causing the correction member to move into the field of view of the camera, and causing the correction mark of the correction member to coincide with the reference mark in the field of view; Recording the coordinate of the robot arm on the coordinate system of the robot arm in step E as a second coordinate; G, according to the A second coordinate scale and calculates the rotation axis of the robot on the calibration plane. A method of correcting a robotic arm correction system according to claim 1, wherein the reference mark is located at a center of photography of a field of view of the camera. A method of correcting a robotic arm correction system according to claim 1, wherein the correction plane is perpendicular to an optical axis of the camera. The method of correcting a robotic arm correction system according to claim 1, wherein the robot arm grasps an edge position of the correcting member and is away from a position of the correction mark. The method for correcting a mechanical arm correction system according to claim 1, wherein the correction member has a plane, and the correction mark is disposed on the plane; and in step B, further comprising controlling the rotation of the mechanical arm such that the correction member This plane is perpendicular to the optical axis of the camera. The method of correcting a robot arm correction system according to claim 1, wherein the predetermined angle is 180 degrees. The method for correcting a robotic arm correction system according to claim 1, wherein in step G, a coordinate of a rotation axis of the robot arm on the correction plane is a midpoint of the first coordinate and the second coordinate.