JP2568005B2 - How to set face-eye, distance and rotation angle of hand eye - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface straightness and distance setting method for teaching a hand eye the optical axis direction with respect to an object to be imaged, the distance from the object to be imaged, and the rotation angle of the object to be imaged.

[0002]

2. Description of the Related Art Conventionally, it has been proposed to mount a TV camera (hereinafter, also referred to as a hand eye) having a two-dimensional solid-state image pickup device on the hands of various multi-axis robots to support the handwork of the robot. When using this hand eye, as a part of the calibration work or the teaching work for the object to be imaged, as a part of the calibration work or the teaching work, the face-to-face setting to align the optical axis direction with the predetermined direction of the subject to be imaged (face-out), It is necessary to set the distance (set distance) to set the hand eye at a predetermined distance from the object to be imaged, and in some cases, a predetermined direction orthogonal to the optical axis of the camera with respect to the direction orthogonal to the base axis of the imaged object. It is also necessary to perform the rotation angle setting (rotation angle setting) so that

Conventionally, these operations have been visually set by an operator using a measurer or the like.

[0004]

However, in the above-mentioned method, the accuracy of straightening out the surface, measuring the distance, and measuring the rotation angle is poor, and there is a problem depending on the skill of the operator. In addition, there is a problem that it takes too much time to set it precisely. It is conceivable that the above-mentioned setting work is performed by processing the image information of the object to be imaged captured by the hand eye, but the shape of the part to be imaged of the object to be imaged, that is, the shape near the gazing point is not constant, and It is usually quite difficult to perform the above setting work accurately from the shape of the object to be imaged near the viewpoint.

The present invention has been made in view of the above problems, and it is an object to be solved to provide a method capable of performing the above-mentioned setting operation of the hand eye with high accuracy and in a short time.

[0006]

The setting method of the first invention is as follows.
A method for setting a plane of a hand eye in which an optical axis of the hand eye, which is a camera fixed to a three-dimensionally movable hand provided in a multi-axis robot, is aligned with a base axis of an object to be imaged,
An attachment having two planes parallel to each other and a predetermined base point is prepared, the base axis and the base point are aligned, and the predetermined locking of the surface of the object to be imaged is performed with the base axis and the two planes orthogonal to each other. The attachment is locked at a point, the optical axis of the camera, that is, the image center is aligned with the base point, and the position to set the optical axis is obtained from the position information of the two surfaces output from the camera, It is characterized in that the hand eye is moved so that the optical axis matches the position.

The position information of the two surfaces is position information obtained from the contour line of each surface or the line or point formed on each surface. If the base axis and the optical axis are different, the point distances or line distances on both surfaces on the image pickup screen, which can be regarded as being perpendicular to the optical axis, change. Therefore, it may be compared with a reference value stored in advance. Or, extracting the first point on the first plane and the second and third points provided on the second plane with the first point interposed therebetween,
The camera may be moved so that the first distance between the first point and the second point is equal to the second distance between the first point and the third point. Preferably, the above operation is performed on the screen in two directions perpendicular to each other.

In a preferred aspect thereof, an inner point located at a predetermined portion on the first plane and an inner point located outside the inner point as viewed in the optical axis direction and at a predetermined portion on the second plane. A position at which an attachment having three or more outer points and a predetermined base point is prepared, and the ratio of each distance between the inner point and the outer point on the screen of the camera is a predetermined ratio stored in advance. The camera is set to and the normal direction of the hand eye is set.

In another preferred form thereof, concentric circles are extracted from both sides. Then, the respective center point positions are extracted, and the optical axis is aligned with the intermediate point between the two center positions. In the present specification, the optical axis in the visual coordinate system of the camera means a predetermined point on the screen. Second
According to the setting method of the invention, the hand eye is set in a state in which an optical axis of a hand eye formed of a camera fixed to a three-dimensionally movable hand provided in a multi-axis robot is aligned with a base axis of the object to be imaged. A method for setting a distance of a hand eye set to a position separated by a predetermined distance from, wherein an attachment provided with two measurement points provided on a predetermined plane at a predetermined distance and a predetermined base point is prepared, The attachment is locked at a predetermined locking point on the surface of the object to be imaged with the base axis and the base point aligned and the base axis and the plane orthogonal to each other, and the optical axis of the camera is aligned with the base axis. In addition, the camera is set at a position where the pixel distance between the two points on the screen of the camera becomes a predetermined reference pixel distance stored in advance.

In the setting method of the third invention, a predetermined visual orthogonal direction orthogonal to the optical axis of a hand eye, which is a camera fixed to a three-dimensionally movable hand provided in a multi-axis robot, and an object to be imaged. A method for setting a rotation angle of a hand eye that matches a predetermined orthogonal direction to an object to be imaged that is orthogonal to a base axis, the attachment including a straight line provided on a predetermined plane and extending in a predetermined direction, and a predetermined base point. And aligning the base axis with the base point, and locking the attachment at a predetermined locking point on the surface of the object to be imaged with the base axis and the plane orthogonal to each other, and the camera on the base axis. And the optical axis is matched, and the linear direction is matched with a predetermined direction on the visual coordinate system of the camera by the movement of the camera.

[0011]

According to the surface straightness setting method of the first invention described above,
The attachment is locked at a predetermined locking point of the object to be imaged so that at least two surfaces parallel to each other are orthogonal to the base axis of the object to be imaged, and the perpendicular direction is determined by the image information obtained from the two surfaces of the attachment. The determination, that is, the optical axis is matched with the base axis of the object to be imaged.

By doing so, it is possible to perform the work for straightening the surface with high accuracy, that is, the work for aligning the optical axis with the base axis of the object to be imaged. Further, since the work can be automated easily, the work time can be reduced. It can also be shortened. In the setting method of the second invention described above, the attachment is locked at a predetermined locking point of the object to be imaged such that the one surface is orthogonal to the base axis of the object to be imaged, and two measurement points with known distances on the one surface are imaged. However, the hand eye is moved to a position where the pixel distance between these two points becomes a predetermined reference pixel distance stored in advance.

With this configuration, the distance can be set with high accuracy,
That is, the hand eye can be set at a predetermined position in the optical axis direction from the object to be imaged. Further, since the work can be easily automated, the work time can be shortened. In the setting method of the third invention described above, the attachment is locked at a predetermined locking point of the object to be imaged so that the one surface is orthogonal to the base axis of the object to be imaged, and a straight line of a known direction on the one surface is imaged. The hand eye is moved so that this linear direction is a predetermined direction on the screen of the camera.

With this configuration, the rotation angle can be set with high accuracy, that is, the predetermined axis on the screen of the hand eye can be aligned with the predetermined axis orthogonal to the base axis of the object to be imaged.
Further, since the work can be easily automated, the work time can be shortened.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A machine tool device using an embodiment of the present invention is shown in FIG. This device is a robot controller for control.
A multi-axis robot 1 having a la (hereinafter simply referred to as controller) 10 and capable of moving a hand 11 three-dimensionally, and a hand eye 3 attached to a hand 2 of the multi-axis robot 1.
The hand eye 3 stores a lens system (not shown) having an optical axis 30 and a two-dimensional solid-state image pickup device (not shown) which is arranged orthogonal to the lens system to pick up an image.

A calibration plate 4, which is an object to be imaged, is arranged at a predetermined position just below the turning range of the hand 11. The calibration plate 4 is a thick metal plate having a hole 40 as a locking point, and is a calibration, that is, a visual coordinate system of the hand eye 3 and a coordinate system of the robot controller. Used for matching (correction) work. The hand eyes 3 are arranged directly above the calibration plate 4 with a predetermined distance therebetween.

Although each setting work in this embodiment is a pre-stage process of the above-mentioned calibration (coordinate system matching) work, it is used for applications other than calibration, such as teaching, that is, robot coordinate system. It can also be applied to the case of teaching the work coordinate points of the work object of the robot. Hereinafter, each setting operation will be described in order. (Direct Surface Out) First, the direct surface out will be described with reference to FIG.

In FIG. 2, the calibration plate is shown.
The plate 4 is arranged at a predetermined position on the flat floor surface, and the plane attachment 5 is arranged on the calibration plate 4. The surface attachment 5 has a flat lower surface 53 and is mounted on the flat upper surface of the calibration plate 4, and a calibration plate that projects downward from the center of the disk portion 55. Hole 40
And a lower shaft portion 54 that is fitted in close contact with the upper disc portion 55 and an upper shaft portion 56 that projects upward from the center of the disc portion 55. The upper shaft portion 56 and the lower shaft portion 54 are coaxial with the disk portion 55, and therefore, the attachment axis center is aligned with the base axis A which is the axis center of the hole 40. And the disc portion 55
The upper surface 52 of the upper shaft portion 56 and the upper surface 52 of the upper shaft portion 56 are 2 in the first invention.
Make up the surface.

The contours of the upper shaft portion 56 and the disk portion 55 are circles C1 and C2 when imaged from above, and the diameter of the circle C1 is designed to be d1 and the diameter of the circle C2 is designed to be d2 (see FIG. 3). A procedure for fully automatically performing this surface straightening using the robot controller 10 will be described below with reference to the flowchart of FIG. First, the hand 11 is controlled to move the hand eye 3 to a position substantially directly above the calibration plate 4, and the optical axis 30 is substantially aligned with the base axis A, so that the distance L between the attachment 5 and the hand eye 3 is adjusted. Reference distance L
It is made to approximately match o (100). In this embodiment, the optical axis 30 is located at the center pixel of the screen.

Next, the attachment 5 is imaged to capture an image signal (101), and a circle C is obtained from the obtained image signal.
1, C2 are extracted, they are normalized into a perfect circle to obtain normalized circles C1 ′ and C2 ′, and the center coordinate points (in the visual coordinate system) P1 (x1, of the normalized circles C1 ′ and C2 ′ are obtained. y1),
P2 (x2, y2) is calculated (102). It should be noted that these image processes are performed by an image processor (not shown) built in the robot controller 10.

Next, the hand 11 is moved so that the center point P1 of the normalized circle C1 'which is the inner circle is located at the center position (optical axis 30) of the screen (see FIG. 5) (104). Next, a straight line Lx (see FIG. 5) connecting the center coordinate points P1 (x1, y1) and P2 (x2, y2) is obtained, and the hand eye 3 is moved to a plane including this straight line Lx and the optical axis 30. Within the straight line Lx
(106). At this time, the swing angle of the hand eye 3 is set to an amount corresponding to the size of the straight line Lx (correctly, an amount having a trigonometric function relationship).

Next, the hand 11 is again moved so that the center point P1 comes to the center position (optical axis 30) of the screen (see FIG. 5).
It is moved (108). Next, it is checked whether or not the length of the straight line Lx is smaller than the minute length ΔL. If it is smaller, it is determined that the surface straightening has been performed, and the routine is terminated. Repeat Chin.

With this configuration, since the attachment 5 suitable for the surface straightening is used, the surface straightening can be automatically and highly accurately executed. Further, in this embodiment, the optical axis 30 is aligned with the optical axis 30 which is the center line of the hole 40 of the calibration plate 4, that is, the hole 4
The optical axis 30 can be set at the center of 0. Although the above-described embodiment describes the straight surface attachment using the straight surface attachment 5, the shape itself of the straight surface attachment 5 also has a great feature. That is, this attachment 5
Has two surfaces parallel to each other and orthogonal to the axis, and concentric circles can be extracted from these two surfaces. Therefore, the surface straightening can be easily performed by the direction and length of the straight line connecting the center points of both circles.

The attachment plate 5 can be locked to the calibration plate 4 not only by such a fitting structure but also by another method. For example, when the calibration plate 4 is a magnetic body, the attachment may be a magnet. Fig. 6 Surface attachment 5a
FIG. In this attachment 5a, the upper shaft portion 56a has a truncated cone shape. In this case,
It is preferable to illuminate the illumination light in a direction parallel to the optical axis 30. In this way, the illumination light is totally reflected by the slope 58a, and the upper surfaces 51a and 52a and the slope 58a can be distinguished from each other. Of course, either the slope 58a or the upper surfaces 51a and 52a may be colored. Also in this case, the upper surface 51a of the upper shaft portion 56a and the upper surface 52a of the disk portion 55a are two surfaces in the first invention. (Distance Out) Next, distance out will be described with reference to FIG.

After the above-mentioned surface straightening and optical axis alignment, as shown in FIG. 8, a calibration plate 4 is formed.
Place the distance attachment 6 on. The distance attachment 6 has a flat lower surface 63 and is placed on the flat upper surface of the calibration plate 4, and a disc portion 65 is provided so as to project downward from the center of the disc portion 65. 4 has a lower shaft 64 fitted tightly into the hole 40, and a circular bottomed hole 66 is formed in the center of the disk portion 65. Here, the bottomed hole 6
6, the lower shaft 64, and the disk portion 65 are coaxial with each other. Therefore, the axis of the attachment 6 is the axis of the hole 40,
That is, it matches the base axis A. The contour of the bottomed hole 66 becomes a circle C3 when the image is taken from above, and the diameter of the circle C3 is designed to be do (see FIG. 9). 2 in the second invention
The measurement points are the two points that are farthest from each other on this circle C3.

This distance measurement is performed by the robot controller 10
The procedure shown in the flowchart of FIG.
With reference to FIG. First, an image is captured and an image signal is captured (200), and the captured image signal is processed by an image processor to form a circle C3 which is the contour of the bottomed hole 66.
The average diameter d of is calculated (202). Next, it is checked whether the absolute value of the difference (d-do) between the average diameter d and the true diameter do stored in advance is smaller than the minute value Δd (20
4) If it is smaller, the routine is terminated (204), and if not, it is checked whether d is smaller than do (20).
6) If it is smaller, bring the hand eye 3 closer by a predetermined distance (2
10) If not, the hand eye 3 is separated by a predetermined distance (210) and returned to 204.

However, the true diameter do stored in the controller 10 is stored as a distance obtained on the screen when the hand eye 3 is positioned at the reference distance Lo, that is, a pixel distance, and the average. The diameter d is also displayed in pixel distance. As described above, in this embodiment, the distance from the attachment 6 of the hand eye 3 is detected by the size of the pixel distance of a straight line (diameter in this case) formed on the attachment 6 and having a known length. Therefore, it is possible to perform distance measurement with high accuracy and high speed. (Rotation angle adjustment) Next, regarding rotation angle adjustment, FIG. 11 and FIG.
It will be described based on 2.

The term "rotation angle adjustment" means that the direction of the reference axis of the screen, that is, the visual coordinate system, coincides with the predetermined direction of the object to be imaged. In this embodiment, the object to be imaged is a molded steel plate member 7 for a vehicle body, and a lower shaft portion 81 of a rotation angle setting attachment 8 is fitted into a hole 70 provided therein. Before performing this rotation angle adjustment, the hole 70 is formed by using the above-described surface straightening and distance measuring methods.
On the other hand, it is assumed that the hand eye 3 has finished the surface straightening and the distance finding.

As shown in FIG. 12, the rotation angle setting attachment 8 is a rectangular aluminum plate having a lower shaft portion 81 protruding from the center of the back surface thereof, and the polished surface thereof has no circular recesses 82 to 84. These recesses 8 are formed in the through holes.
The bottom surface and inner side surfaces of 2 to 84 are painted black. Here, the center point of the recess 82 is located on the center axis of the hole 70, that is, the base axis A in the present invention, and the recesses 83 and 84 are located.
Are formed on the opposite side of the concave portion 82 at equal distances. The center point of each recess is located on the straight line m. The concave portion 82 is for aligning the base axis A and the optical axis 30. The attachment 8 is arranged so that the straight line m is horizontal.

This rotation angle is determined by the robot controller 1
The procedure for fully automatic operation using 0 will be described below with reference to the flowchart of FIG. First, image pickup is performed to capture an image signal (300), and the optical axis 30 of the hand eye 3 is aligned with the base axis A, and then the captured image signal is processed by an image processor to form a circle C which is a contour of the recesses 83 and 84.
The center coordinate points of 4 and C5 are calculated (302). Next, a straight line m connecting both center coordinate points on the screen is obtained (304), and an angle between the obtained straight line m and the horizontal scanning direction of the screen (x-axis direction in the visual coordinate system) is obtained (306).

Next, if the angle Θ is smaller than the minute value ΔΘ, the hand eye 3 is considered to be in a good posture about the optical axis, and the routine is ended. If not, only the angle corresponding to the magnitude of the angle Θ. Rotate the hand eye 3 and return to step 302. In this way, the rotation angle can be accurately and rapidly determined by the angle between the clear line m formed on the attachment 6 and having a known length and the predetermined direction on the screen.

[Brief description of drawings]

FIG. 1 is a schematic view of a multi-axis robot system using the setting method of the present invention,

FIG. 2 is a cross-sectional view showing a state in which a vertical attachment is attached,

3 is a plan view of the plane attachment of FIG. 2,

FIG. 4 is a flow chart showing a surface directing routine,

FIG. 5 is an explanatory diagram showing a screen,

FIG. 6 is a cross-sectional view showing a state in which another surface upright attachment is attached,

7 is a plan view of the surface attachment of FIG. 6,

FIG. 8 is a cross-sectional view showing a state in which a distance attachment is attached,

9 is a plan view of the distance attachment of FIG. 9,

FIG. 10 is a flow chart showing a distance setting routine.

FIG. 11 is a cross-sectional view showing a state in which a rotation angle setting attachment is attached,

12 is a plan view of the distance attachment of FIG. 11,

FIG. 13 is a flowchart showing a rotation angle setting routine.

[Explanation of symbols]

3 is a hand eye, 4 is a calibration plate 4,
5 is a hand eye, 30 is an optical axis, and 51 and 52 are two planes.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Yamamoto 1-1-1, Asahi-cho, Kariya city, Aichi Toyota Koki Co., Ltd. (56) References JP-A-2-83183 (JP, A) JP-A-2 -99802 (JP, A) JP 61-270094 (JP, A) JP 1-116401 (JP, A)

Claims (3)

(57) [Claims] 1. A face-eye straightening method for aligning an optical axis of a hand-eye comprising a camera fixed to a three-dimensionally movable hand provided in a multi-axis robot with a base axis of an object to be imaged. An attachment having two parallel planes and a predetermined base point is prepared, the base axis is aligned with the base point, and the base axis and the two planes are orthogonal to each other, the predetermined locking point on the surface of the object to be imaged. The attachment is locked to, the optical axis of the camera, that is, the image center is aligned with the base point, and the position to set the optical axis is obtained from the positional information of the two surfaces output from the camera,
A method for setting a face-orientation of a hand eye, wherein the hand eye is moved so that the optical axis matches the position. 2. The hand eye from the object to be imaged in a state where the optical axis of the hand eye consisting of a camera fixed to a three-dimensionally movable hand provided in a multi-axis robot is aligned with the base axis of the object to be imaged. A method for setting a distance of a hand eye set to a position separated by a predetermined distance, wherein an attachment provided with two measurement points provided on a predetermined plane at a predetermined distance from each other and a predetermined base point is prepared. The attachment is locked at a predetermined locking point on the surface of the object to be imaged with the base axis and the base point aligned and the base axis and the plane orthogonal to each other, and the optical axis of the camera is aligned with the base axis. In addition to the above, the hand eye distance setting method is characterized in that the camera is set at a position where the pixel distance between the two points on the screen of the camera becomes a predetermined reference pixel distance stored in advance. 3. A predetermined visual orthogonal direction orthogonal to an optical axis of a hand eye formed of a camera fixed to a three-dimensionally movable hand provided in a multi-axis robot and a predetermined orthogonal direction to a base axis of an object to be imaged. A method for setting a rotation angle of a hand eye that matches a direction orthogonal to an object to be imaged, wherein an attachment provided with a straight line provided on a predetermined plane and extending in a predetermined direction, and a predetermined base point is prepared. And the base point are matched, and the attachment is locked at a predetermined locking point on the surface of the object to be imaged with the base axis and the plane orthogonal to each other, and the optical axis of the camera is matched with the base axis. At the same time, the rotation angle setting method for a hand eye is characterized in that the straight line direction is matched with a predetermined direction on a visual coordinate system of the camera by moving the camera.