JP2005271103A - Working robot and calibration method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working robot and a calibration method, easily and accurately adjusting the positional relationship between an arm and a three-dimensional scanner. <P>SOLUTION: This working robot includes: an arm information obtaining means for obtaining the position information on the tool flat surface of a plate-like tool provided in a predetermined position and the position information on the origin of the tool on the tool flat surface using an arm; a scanner information obtaining means scanning the tool flat surface using the three-dimensional scanner to obtain the data of a dot group of the tool flat surface and obtaining the position information of the arm in scanning; a vector information obtaining means obtaining the vector information of a normal vector on the tool flat surface having a predetermined relationship to the origin of the tool from the data of a dot group; and a position adjusting means for adjusting the positional relationship between the arm and the three-dimensional scanner using the position information on the tool flat surface, the position information on the origin of the tool, the vector information on the normal vector and the position information on the arm in scanning. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a working robot having a three-dimensional scanner on a working arm and a calibration method thereof.

  Recent work robots include a three-dimensional scanner on the arm of the work robot, specify a position for welding or the like based on information from the three-dimensional scanner, and drive the arm. In order to accurately perform welding or the like, it is necessary to grasp the positional relationship between the arm and the three-dimensional scanner and perform calibration to adjust the relationship.

Calibration with a working robot having a three-dimensional scanner on a conventional arm has been performed by setting the origin on the plane of the jig (jig plane) for calibration. In order to perform this calibration, first, information on the jig plane (vector information) is obtained by moving the arm of the working robot in contact with a portion having a predetermined relationship with the origin on the jig plane. obtain. Next, a three-dimensional scanner is attached on the same vector as the coordinate system of the working robot, and the origin on the jig plane is scanned with the three-dimensional scanner. Then, calibration is performed based on information on the coordinate system of the working robot, vector information, and information on the origin of the three-dimensional scanner.
In addition, since this prior art is not related to literature public knowledge, there is no prior art literature information to be described.

  However, it is difficult to move the arm of the work robot while accurately contacting the surface of the jig with the calibration of the conventional work robot. It took a long time to get the information. In addition, it is difficult to move the arm accurately, and it is difficult to increase the accuracy of calibration.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a working robot capable of easily and accurately adjusting the positional relationship between an arm and a three-dimensional scanner and a calibration method thereof.

  The work robot according to claim 1 uses the arm to acquire the position information of the jig plane of the plate-shaped jig provided at a predetermined position and the position information of the jig origin on the jig plane. Scanning the jig plane using a three-dimensional scanner to acquire the data of the point plane of the jig plane, and the scanner information acquisition means for acquiring the position information of the arm at the time of scanning, Vector information acquisition means for acquiring vector information of normal vectors on the jig plane having a predetermined relationship with the jig origin from the point cloud data, jig plane position information, jig origin position information, method Position adjustment means for adjusting the positional relationship between the arm and the three-dimensional scanner using the vector information of the line vector and the position information of the arm at the time of scanning is provided.

  The working robot according to claim 2, wherein the arm information acquisition unit acquires information on three points on the jig plane by bringing the arm into contact with any three points on the jig plane. Position information is acquired, and the position information of the jig origin is acquired by bringing the arm into contact with the jig origin on the jig plane.

  The working robot according to a third aspect is characterized in that the scanner information acquiring means scans the jig plane in a state where the arm is in contact with the jig origin.

  According to a fourth aspect of the present invention, the working robot scans two circles drawn on the jig plane with a three-dimensional scanner, and acquires vector information of normal vectors.

  The work robot calibration method according to claim 5, wherein the position information of the jig plane of the plate-like jig provided at a predetermined position and the position of the jig origin on the jig plane is obtained using an arm. Information, and using a three-dimensional scanner to scan the jig plane, acquire point cloud data on the jig plane, acquire arm position information at the time of scanning, and then obtain point cloud data. From this, the vector information of the normal vector on the jig plane having a predetermined relationship with the jig origin is acquired, and then the position information of the jig plane, the position information of the jig origin, the vector information of the normal vector, and the scan The positional relationship between the arm and the three-dimensional scanner is adjusted using the positional information of the arm at the time.

  The work robot calibration method according to claim 6, wherein the arm is brought into contact with any three points on the jig plane to acquire information on three points on the jig plane, and position information on the jig plane. And the position information of the jig origin is obtained by bringing the arm into contact with the jig origin on the jig plane.

  The work robot calibration method according to claim 7 is characterized in that the jig plane is scanned in a state where the arm is in contact with the jig origin.

  The working robot calibration method according to claim 8 is characterized in that the vector information of the normal vector is acquired by scanning two circles drawn on the jig plane with a three-dimensional scanner.

  According to the first aspect of the present invention, the data of the point group on the jig plane is acquired using the three-dimensional scanner, and the position information of the arm at the time of scanning is acquired to acquire the vector information. For this reason, it is not necessary to acquire information while moving the arm, the time for acquiring information for calibration is suppressed, and the accuracy of calibration is improved.

  According to the second aspect of the invention, since various types of position information are obtained by bringing the arm into contact with each point on the jig plane, it is easier than when obtaining information while moving the arm. The position information can be obtained accurately.

  According to the invention of claim 3, the number of times of acquisition of the position information of the jig origin can be reduced to one by scanning the jig plane while the arm is in contact with the jig origin. The work efficiency is improved.

  According to the invention of claim 4, by using two circles that can easily calculate the position of the center point from the point cloud data, it is easy to calculate a normal vector that passes through the centers of the two circles, and to acquire vector information. It can be done accurately and quickly.

  According to the invention of claim 5, using the three-dimensional scanner, the data of the point group on the jig plane is acquired, and the position information of the arm at the time of scanning is acquired to acquire the vector information. For this reason, it is not necessary to acquire information while moving the arm, the time for acquiring information for calibration is suppressed, and the accuracy of calibration is improved.

  According to the invention of claim 6, since various position information is acquired by bringing the arm into contact with each point on the jig plane, it is easier than when acquiring information while moving the arm. The position information can be obtained accurately.

  According to the seventh aspect of the present invention, the number of times of acquisition of the position information of the jig origin can be reduced to one by scanning the jig plane while the arm is in contact with the jig origin. The work efficiency is improved.

  According to the invention of claim 8, by using two circles that can easily calculate the position of the center point from the point cloud data, it is easy to calculate a normal vector that passes through the centers of the two circles, and to acquire vector information. It can be done accurately and quickly.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. The work robot described in this embodiment is a work robot for welding, assembling, and painting industrial products, and includes a three-dimensional scanner on the arm of the work robot.

  FIG. 1 is a configuration diagram showing a configuration example of a working robot according to the present invention. FIG. 2 is an explanatory view showing the calibration of the working robot, and FIG. 3 is a plan view showing the jig. FIG. 4 is a flowchart showing the calibration operation. FIG. 5 is an explanatory diagram showing details of the calibration calculation. FIG. 6 is an explanatory diagram showing a point cloud acquired by a three-dimensional scanner, and FIG. 7 is an explanatory diagram showing parameter settings necessary for calibration. FIG. 8 is an explanatory diagram showing the result of calibration using point clouds.

  In the figure, a working robot 1 is a robot for welding, assembling, painting, and the like of industrial products, and includes an arm 5 that is driven three-dimensionally. In the present embodiment, a description will be given as a working robot performing welding with a torch 6 at the tip of the arm 5. A three-dimensional scanner 7 is attached to the arm 5 near the upper end of the torch 5 of the working robot 1. The three-dimensional scanner 7 recognizes the welding position on the torch 6 and corresponds to the eyes of the work robot 1.

  The working robot 1 has a robot coordinate system that grasps the positions of the arm 5 and the torch 6 by itself, and similarly, the three-dimensional scanner 7 also has a scanner coordinate system. Then, it is connected to the arm 5 and the three-dimensional scanner 7 that takes in the information of both coordinate systems and has a tool coordinate system for actually controlling the welding operation and controls the working robot 1. This is an arithmetic unit 10. The arithmetic unit 10 is configured by a computer, and performs calibration of the working robot 1 and control of welding work described below by a program. However, the arithmetic device 10 is not limited to a computer, and may be configured by a combination of hardware or a combination of hardware and software.

  In addition, a fixed base 15 for fixing an object to be welded is disposed in the work range of the arm 5 of the work robot 1. In order to perform calibration, a jig 20 for performing calibration is fixed on the fixing table 15.

  Here, calibration refers to grasping the positional relationship between the arm 5 and the three-dimensional scanner 7 and adjusting the relationship. In other words, it can also be understood as grasping the offset amount of each coordinate system for guiding to. That is, if this calibration is not performed correctly, the torch 6 will not be directed to the position of the object recognized by the three-dimensional scanner 7 and accurate welding will not be possible.

  Next, the jig 20 will be described. The jig 20 is a substantially rectangular thin plate, the jig plane 21 on the surface is smooth, and a large circle 22 and a small circle 23 are drawn as shown in FIG. In addition, although it is not always necessary, two straight lines are drawn. The point where these two are orthogonal is defined as the jig origin PA on the jig plane 21. However, this orthogonal point does not necessarily have to be determined as the origin, and may be determined as an arbitrary point on the jig plane 21. Further, the jig 20 is not necessarily fixed so that the jig plane 21 is horizontal.

  Next, calibration of the working robot 1 will be described. In the following description, the reference numerals in parentheses correspond to the reference numerals in the flowchart of FIG. First, the required position of the jig plane 21 is taught to the work robot 1 (S101). Information to be taught includes position information (three-dimensional information) of the jig plane 21 on which position the jig plane 21 is located with respect to the work robot 1 and position information (3 of the jig origin on the jig plane 21). Dimension information). The position information of the jig plane 21 includes tilt information of the jig plane 21. That is, this teaching (S101) constitutes arm information acquisition means. In order to acquire position information of the jig plane 21, the arm 5 is brought into contact with three points of the jig plane 21. Specifically, the arm 5 is not directly applied to the jig plane 21, but the tip of the torch 6 is brought into contact with the jig plane 21. Further, it is more preferable to replace the torch 6 with a bar material that becomes a dummy of the torch 6.

  Specifically, the three points where the torch 6 abuts are P0, P1, and P2 shown in FIG. These are arbitrary points on the jig plane 21 and have no particular mutual relationship. However, P0 is the same point as the origin PA. And the arm 5 is operated and the positional information on each point is acquired. The acquired information is once stored as a robot coordinate system (coordinate data) in the work robot 1 (S102). In order to grasp the position of the jig plane 21, it is sufficient to acquire position information of three points on the jig plane 21. That is, since two of the three points are present on one straight line, and the remaining one point is necessarily in a relation in which a perpendicular line can be placed on the straight line, the position information of the jig plane 21 is obtained. This is because the x-axis, y-axis, and z-axis can be grasped.

  Next, the jig plane 21 is scanned by the three-dimensional scanner 7 to acquire point cloud data (S103). That is, the acquisition of the point cloud data (S103) constitutes scan information acquisition means. As shown in FIG. 3, the scanning position is a position where the torch 6 contacts the jig origin PA. In addition, the position information of the torch 6 of the jig origin PA at the time of scanning is also saved simultaneously. It should be noted that the position of the torch 6 when acquiring the point cloud data is not necessarily the jig origin PA.

  Next, the acquired information (coordinate data) is transmitted from the work robot 1 to the arithmetic unit 10 (S104). Specific examples of the transmitted information are shown in the upper and middle sections of FIG. That is, the scan coordinates (X, Y, Z, Rx, Ry, Rz) robot coordinates are the position information of the torch 6 at the time of scanning, and the “index robot coordinates P0, P1, P2” are on the jig plane 21. This is position information of the arm 5. Rx, Ry, and Rz represent the rotation angle of the torch 6.

  Further, the offset amount between the origin of the jig 20 and the center 22a of the great circle 22 is input to the arithmetic unit 10 (S105). The offset amount is a value determined when the jig 20 is created. Specifically, the value is shown in “Jig mark center position offset” in the lower part of FIG.

  Next, in the point group, portions corresponding to the great circle 22 and the small circle 23 are designated manually (S106). Then, a calibration calculation is performed (S107). This calibration calculation (S107) constitutes a position adjusting means.

  Next, details of the calibration calculation will be described with reference to FIG. First, processing in the scanner coordinate system is performed from the information (FIG. 5-A) such as position information obtained above (FIG. 5-B). In the processing in the scanner coordinate system (FIG. 5-B), first, cluster processing is performed on the point group data of the great circle 22 and the small circle 23 of the jig 20 to obtain the jig plane 21 and the great circle 22. Then, the small circle 23 is recognized, and the coordinates of the center 22a of the large circle 22, the center 23a of the small circle 23, and the jig plane 21 are obtained (see FIG. 6). The coordinate system here is a scanner coordinate system. By the cluster processing, a normal vector 24 on the jig plane 21 that is revealed by the jig origin PA (P0) and the centers 22a and 23a of the great circle 22 and the small circle 23 on the jig plane 21 is calculated. The That is, the calculation of the normal vector 24 constitutes a vector information acquisition unit. Then, with reference to information on the normal vector 24 and the offset amount between the jig origin PA and the center 22a of the great circle 22, the local coordinate system of the jig plane 21 in the scanner coordinate system (the coordinates of the jig plane 21) System) and the coordinates of the jig origin PA. Further, a conversion matrix between the scanner coordinate system and the local coordinate system of the jig plane 21 in the scanner coordinate system is created.

  Next, processing in the robot coordinate system is performed from the information (FIG. 5-A) such as position information obtained as described above (FIG. 5-C). In the processing in the robot coordinate system (FIG. 5-C), first, from the origins P0, P1, P2 of the jig plane 21, the local coordinate system of the jig plane 21 in the robot coordinate system (the coordinate system of the jig plane 21). ) And the coordinates of the jig origin PA (P0). Further, a conversion matrix between the robot coordinate system and the local coordinate system of the jig plane 21 in the robot coordinate system is created.

  Next, a conversion matrix between the robot coordinate system and the scanner coordinate system is created from the process of the scanner coordinate system (FIG. 5-B) and the process of the robot coordinate system (FIG. 5-C) (FIG. 5-D). Specifically, using the fact that the local coordinate system of the jig plane 21 in the robot coordinate system and the local coordinate system of the jig plane 21 in the scanner coordinate system are the same coordinate system, the robot coordinate system and the scanner coordinates. Create a system transformation matrix.

  Next, a conversion matrix between the robot coordinate system and the tool coordinate system is created (FIG. 5-E). Specifically, a conversion matrix between the robot coordinate system and the tool coordinate system is created from X, Y, Z, Rx, Ry, and Rz that are position information of the torch 6 at the time of scanning.

  Next, a conversion matrix between the tool coordinate system and the scanner seating system is created (FIG. 5-F). Specifically, it is created from a conversion matrix between the robot coordinate system and the tool coordinate system and a conversion matrix between the robot coordinate system and the scanner coordinate system. The tool coordinate system and the scanner coordinate system are created because they can be converted via the robot coordinate system. This conversion matrix is finally used to adjust the positional relationship between the arm 5 and the three-dimensional scanner 7 and to accurately drive the arm 5 based on information from the three-dimensional scanner 7. That is, the final object of the present invention is the conversion matrix between the tool coordinate system and the scanner coordinate system.

  As described above, the three-dimensional scanner 7 is used to acquire the point cloud data of the jig plane 21 and the position information of the arm 5 at the time of scanning to acquire the vector information. For this reason, it is not necessary to acquire information while moving the arm 5, and it is possible to reduce the time for acquiring information for calibration and improve the accuracy of calibration.

  Further, since various pieces of position information are acquired by bringing the arm 5 (torch 6) into contact with each point on the jig plane 21, it is easier than when acquiring information while moving the arm 5. The position information can be obtained accurately.

  Furthermore, by scanning the jig plane while the arm 5 is in contact with the jig origin PA (P0), the number of times of obtaining the position information of the jig origin can be reduced to one. Efficiency. However, calibration is possible even if it is not the jig origin PA or P0.

  Furthermore, by using two circles that can easily calculate the position of the center point from the point cloud data, it is easy to calculate the normal vector 24 passing through the centers of the two circles, the great circle 22 and the small circle 23, and the vector information Acquisition can be performed accurately and quickly. It should be noted that a figure from which vector information can be easily acquired has only to be drawn on the jig plane 21 and is not necessarily a circle, but a circle is more preferable.

  FIG. 8 shows the actual calibration performed. FIG. 8 shows a point group 27 obtained by scanning two objects (a point group 27 a and a point group 27 b) having a peak at the center with the three-dimensional scanner 7. And after performing calibration, the object position 28 and the welding position 29 showing the object position 28 grasped in the scanner coordinate system and the welding position 29 grasped in the tool coordinate system, It is almost the same, indicating that high-precision calibration has been performed.

  As long as it has arm information acquisition means, scanner information acquisition means, vector information acquisition means, and position adjustment means, it is not limited to software, it is realized by a digital circuit that is a combination of analog circuits and logic circuits And can be applied.

It is a block diagram which shows the structural example of the working robot which concerns on this invention. It is explanatory drawing which shows the mode of the calibration of the robot for work. It is a top view which shows a jig | tool. It is a flowchart which shows the operation | movement of a calibration. It is explanatory drawing which shows the detail of a calibration calculation. It is explanatory drawing which shows the point cloud acquired by the three-dimensional scanner. It is explanatory drawing which shows the setting of the parameter required for calibration. It is explanatory drawing which shows the result of calibration by a point group.

Explanation of symbols

1... Working robot 5... Arm 6... Torch 7... 3D scanner 10. ············································ Jig 22 ·················································・ Point cloud

Claims (8)

In a working robot comprising a working arm and a three-dimensional scanner provided on the arm,
Arm information acquisition means for acquiring the position information of the jig plane of the plate-shaped jig provided at a predetermined position and the position information of the jig origin on the jig plane using the arm;
Using the three-dimensional scanner, scan the jig plane, acquire point cloud data of the jig plane, and acquire scanner arm position information at the time of scanning;
Vector information acquisition means for acquiring vector information of normal vectors on the jig plane having a predetermined relationship with the jig origin from the data of the point group;
Using the jig plane position information, the jig origin position information, the normal vector vector information, and the arm position information during scanning, the positional relationship between the arm and the three-dimensional scanner is adjusted. A working robot comprising a position adjusting means. The arm information acquisition means acquires information on three points on the jig plane by bringing the arm into contact with any three points on the jig plane, and acquires position information on the jig plane. ,
2. The work robot according to claim 1, wherein position information of the jig origin is acquired by bringing the arm into contact with the jig origin on the jig plane.   The work robot according to claim 1 or 2, wherein the scanner information acquisition unit scans the jig plane in a state where the arm is in contact with the jig origin.   4. The vector information of the normal vector is acquired by scanning two circles drawn on the jig plane with the three-dimensional scanner. 5. Robot for work. In the calibration method of the working robot for adjusting the positional relationship between the working arm and the three-dimensional scanner provided on the arm,
Using the arm, the position information of the jig plane of the plate-like jig provided at a predetermined position and the position information of the jig origin on the jig plane,
Using the three-dimensional scanner, the jig plane is scanned to obtain point cloud data of the jig plane, and after acquiring the position information of the arm at the time of scanning,
Obtaining vector information of normal vectors on the jig plane having a predetermined relationship with the jig origin from the data of the point group;
Then, using the position information of the jig plane, the position information of the jig origin, the vector information of the normal vector, and the position information of the arm at the time of scanning, the positional relationship between the arm and the three-dimensional scanner is determined. A method for calibrating a working robot, characterized by adjusting. By bringing the arm into contact with any three points on the jig plane, information on three points on the jig plane is obtained, and position information on the jig plane is obtained,
6. The work robot calibration method according to claim 5, wherein the position information of the jig origin is acquired by bringing the arm into contact with the jig origin on the jig plane.   The work robot calibration method according to claim 5, wherein the jig plane is scanned in a state where the arm is in contact with the jig origin.   The vector information of the normal vector is acquired by scanning two circles drawn on the jig plane by the three-dimensional scanner. Calibration method for work robots.

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