JPH0830977B2 - Robot copy control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a robot control device, and more particularly to a robot control device for a robot in which a hand portion of the robot is made to follow the surface shape of a workpiece.

B. SUMMARY OF THE INVENTION The present invention is an apparatus for moving a machining head part of a robot to a teaching point of a workpiece to operate the hand head part with respect to the teaching point. By mounting a three-dimensional measurement sensor that measures the height of the workpiece and the inclination angle of this surface, and automatically measuring the three-dimensional relative position and orientation between the workpiece surface and the machining head, the position and orientation angle of the head can be set to the desired value. The value is automatically controlled.

C. Conventional technology For example, in the case of robots or remote-controlled manipulators installed in processing or dismantling processes such as material polishing, fusing, welding, etc., move the processing head with respect to the robot or manipulator before actually operating it. It is necessary to measure the sequence and operation sequence according to the three-dimensional shape of the workpiece.
A device that determines the three-dimensional movement locus of the processing head is also called a three-dimensional copying device.For example, in a plasma fusing robot, a magnetic sensor is installed near the processing head and used as a material to be cut such as an iron plate. The magnitude of the eddy current generated in the work is detected, and the distance between the machining head and the work surface is calculated from the current value. Therefore, in the actual teaching work, while the operator operates the teaching pendant, the operator visually approaches the machining head to a desired teaching point on the work surface, and also visually observes the attitude angle of the machining head at the teaching point surface. Performs three tasks: aligning the posture of the machining head so that it is at a right angle to the machine, and setting the distance between the machining head and the teaching point on the workpiece surface to a constant value using the sensor described above. It was necessary to make a mistake.

However, when the operator visually performs the teaching work consisting of three works for each teaching point as described above, there is a variation in the set values such as the distance to the working head and the posture angle of the working head between each teaching point. There was a problem that it would occur. As a result, the cut surfaces of the work become uneven, and there are some places where some cuts cannot be made.

D. Problems to be solved by the invention If the above teaching work is performed carefully and accurately in order to avoid the above problems, the teaching work time increases and the time during which the robot actually performs the cutting work There was a problem that the operating rate of the processing head, which indicates the ratio Furthermore, a worker who is skilled in robot operation is required.

In order to deal with the above problem, an operation for moving the robot head to a desired teaching point in a short time without the need for a skilled worker and a work for controlling the posture angle with respect to the headwork surface after the movement to be constant. Two-dimensional position that can automatically teach the robot and work to control the distance to the headwork surface to a constant level, can perform the teaching work to the robot accurately and efficiently, and can greatly improve the operation rate of the robot. A three-dimensional teaching device for a robot mainly for measurement is introduced in JP-A-61-100808 and JP-A-61-100809.

However, in the method of each of the above-mentioned published patent publications, three or more sensors are indispensable, and if any one of these sensors encounters the end portion, the protrusion, the cap portion, etc. of the work surface,
There was a drawback that position correction calculation and posture correction calculation could not be performed. Further, since the correction calculation is an approximate calculation based on two-dimensional data, there is a problem that the calculated correction value has many errors. Furthermore, since the mounting angle α of the sensor with respect to the optical axis of the camera is fixed, there is a drawback that it is not possible to easily deal with rough measurement at a flat place and fine measurement at a convex angle portion.

E. Means for Solving Problems The present invention has been made in view of the above points,
Aiming to provide a high-performance robot copying control device capable of three-dimensionally controlling the position and orientation of the robot's hand part, the robot's hand head part is moved to the teaching point on the workpiece and the robot is moved to the teaching point. On the other hand, in the control device for operating the hand head part, a projector disposed near the hand head part and projecting a pair of slit lights on the workpiece, and a pair of slit images by a pair of slit lights of the projector. An image pickup means for picking up an image, an image detection means for detecting the state of the pair of slit images by the image pickup means, a position between the sensor of the image pickup means and the workpiece based on detection data by the image detection means, and And a calculation means for calculating the posture, the calculation means converting points in the three-dimensional coordinate system of the pair of slit images detected by the image detection means into points on the image of the image pickup means. The position correction data and the posture data are calculated based on the above, and the robot hand head portion is made to follow the surface of the workpiece based on the position correction data and the posture correction data by the calculation means. is there.

F. Action A pair of slit light is projected on the workpiece, the projected pair of slit light is converted into a pair of slit images, and the state of the converted pair of slit images is detected. The position and orientation of the sensor with respect to the workpiece is calculated based on the state detection data of the pair of images, and based on the value obtained by converting the detected point in the three-dimensional coordinate system of the slit image into a point on the image. The position correction data and the posture data are calculated in accordance with the calculated data, and the hand head portion of the robot is made to follow the surface of the workpiece based on these calculated data.

G. Examples Examples of the present invention will be described below with reference to the drawings. 8th
The figure shows a robot to which the present invention is applied. The robot body 1 comprises an operation drive unit 2, a link unit 3 connected to the operation drive unit 2, an arm 4 connected by a link 6a of the link unit 3 and a hand unit 5 connected to the arm 4. Further, in the robot body 1, the link 6a of the link unit 3 has a first rotation shaft 7a rotatably connected to the operation drive unit 2 and the first rotation shaft 7a.
A second rotary shaft 7b that rotatably connects the rotary shaft 7a to the operation drive unit 2, and a third rotary shaft 7b that rotatably connects the link 6b and the arm 4.
A fourth rotation shaft that rotatably connects the rotation shaft 7c to the arm 4.
7d, a fifth rotation shaft 7e that rotatably connects the hand portion 5 to the arm 4, and a sixth rotation shaft 7f that rotatably connects the hand portion 5 to the arm 4. Reference numeral 8 is a plasma torch attached to the hand portion 5, and 9 is a workpiece as a workpiece arranged on the processing table 10.

FIG. 1 is a block diagram of a robot controller according to an embodiment of the present invention, in which 11 is a control unit, which includes a signal conversion circuit 12, an arithmetic processing unit (CPU) 13, and a driver circuit 14. The signal conversion circuit 12 of the controller 11 detects the detection signal S ₁ of the sensor 15.
And outputs the digitized identification signal S ₂ . The arithmetic processing unit 13 is composed of a microcomputer or the like, and receives the identification signal S ₂ and the information signal S ₃ of the robot body 1 and performs arithmetic processing based on these. The driver circuit 13 outputs a drive control signal S ₅ based on the arithmetic signal S ₄ of the arithmetic processing unit 13. The robot body 1 controls the sensor 15 and the processing unit 16 based on the drive control signal S ₅ .

FIG. 2 shows the control device of FIG. 1 more concretely, in which a camera 17, which is an optical sensor, and a slit light projector 18 are used as the sensor 15, and an image identification circuit 19 is used as a signal conversion unit. It is a thing. A plasma torch 8 and a slit light projector 18 are attached to the hand portion 5 of the robot body 1, and a camera 17 is rotatably attached. That is, the sensor 15 is a slit light projection type three-dimensional sensor, and is arranged in parallel with the plasma torch 8 as shown in the figure, and can be moved independently in the vertical direction. Fig. 3 shows the coordinate system of the fusing cutting head part. The slit light projection sensor irradiates the work 9 with slit light having a width of about 1 mm and a length of about 10 mm, and the slit image is deformed according to the shape of the work surface. 20a and 20b are captured by the solid-state camera 17 and the image signal S ₁ is input to the image identification circuit 19. The image discrimination circuit 19 analyzes the image signal S ₁ to perform slit images 20a, 20b.
Is analyzed to analyze the deformation of the work 9, and the analysis data S ₂ is input to the CPU 13. The CPU 13 measures the position and orientation between the surface of the work and the camera, sends a control command S ₃ to the robot body 1 and supplies a control signal S ₄ to the driver circuit 14. The robot body 1 performs a predetermined operation according to the command signal S ₃ and the drive signal S ₅ from the CPU 13. In the example of FIG. 2, the arc operating point for plasma fusing and the slit-camera measuring point are physically different, but by appropriately changing the hand parameter in the control unit 11, it becomes an easy slit-camera measuring point. The operating point of plasma fusing can be moved.

Fig. 4 shows the slit-camera coordinate system. The camera is located at the point z _c on the Z axis, and the focal length f and the angle forming φ with the X axis can be observed in the positive direction of the X axis. ing. The slit images 20a and 20b are arranged in parallel with the X axis at Z = 0 and Z.
The light is emitted in the X-axis direction as two parallel rays centered at = z _k . In FIG. 4, the coordinates of each point are points O (x _o , 0,0), P (x _p , y _p , 0), Q (x _Q , y _Q , 0) on the target surface. Points and points on the slit plane. FIG. 5 shows the relationship between the slit-distance to the work surface (height L, posture angle Δα (tilt angle around the Z axis)) measured by the camera system in FIG. 4, and FIG. 6 shows parallel line slits. It is a figure for explaining the three-dimensional measurement used.

As shown in FIG. 4, if the coordinates of the slit image on the camera image plane are (x ′, y ′), the horizontal length of one pixel of the camera is s, and the vertical length is t, then z _c , Φ, f, s, t are known, and the position (x _p , y _p , z _p ) of the point P is obtained from the point P ′ (x ′ _p , y ′ _p ) on the camera image. Since the point P is a point on the lower slit plane, z _p = φ (1) From the geometrical optical system shown in FIG. 4, tan (A ₁₂ ) = y ′ _p · t / f ∴A ₁₂ = tan ⁻¹ (y ′ _p · t / f) γ ₁₂ = 90 ° −φ−A ₁₂ Therefore, x _p = z _c tan (γ ₁₂ ) = z _c tan (90 ° −φ−A ₁₂ ) ... (2) And The position of the point P is measured from the equations (1) to (3).

In FIG. 5, when the point O is a point on the measurement plane and a point on the X axis, the distance L from the slit image to the measurement surface is L = x _o , and the posture is as illustrated. Two slit lights 20a and 20b (Z = 0 and Z = z _t ) as shown in FIG.
When L is used, the distance L and the postures α and γ are calculated as follows.

Distance: L = x _o (4) Posture: Δα = tan ^-1 {(x _Q −x _p ) / (y _Q −y _p )}…
(5) Δγ = tan ⁻¹ {(x _R −x _O ) / z _t } (6) The above equations (1) to (6) are calculated by the CPU 13 of the control unit 1 shown in FIGS. 1 and 2. It is processed. Based on the calculation processing result, while performing the processing flow of FIG. 7, for example, the work 9 shown in FIG. 8 is automatically controlled, that is, the sensor position and posture in the robot hand portion 5 are controlled by a joystick or the like. As shown in step Q ₁ in Fig. 7, guide the sensor tip to the vicinity of the measurement point. If the video signal of the measuring camera is observed together with the slit pattern on a monitor TV or the like, this operation becomes very easy. Then, the video signal of the slit-camera system is taken in, and the relative position L and the posture (Δα, Δγ) between the camera 17 and the surface of the work 9 are automatically measured by the equations (4) to (6) by image processing (step). Q ₂ ). Next, L = ho (target value) + (Δx, Δα,
Δγ) correction measurement data is transferred to the driver circuit 14,
Allowed to move the sensor head to the correction position and the correction posture (Step Q _3). Finally, the robot position and posture after movement are stored in the storage unit for breakback in the CPU 13 (step Q ₄ ), and the copying teaching process is completed.

H. Effect of the Invention The present invention is as described above, and since three-dimensional position / orientation measurement can be performed by one time capturing of a video signal, high-speed measurement can be performed without locally displacing the sensor head unit.
High-speed measurement is possible and the operating rate of the robot can be greatly improved. Further, since the position and orientation are calculated using three-dimensional data, the correction result is accurate, and stable and high-speed automatic copying operation can be realized even on a curved surface having a discontinuous linear differential coefficient. And so on.

[Brief description of drawings]

FIG. 1 is a block connection diagram of a copying control device for a robot according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing the device of FIG. 1 more specifically, and FIG. 3 is coordinates of a hand portion of the robot. System diagram, FIG. 4 is a coordinate system diagram of the slit and the camera, FIG. 5 is a coordinate system diagram from the slit to the measurement surface, FIG. 6 is a three-dimensional measurement diagram by the slit, and FIG. 7 is a processing flow diagram of the apparatus of FIG. , FIG. 8 is an explanatory view showing the shape of the work and the moving state of the processing head. 1 ... Robot body, 5 ... Hand part, 8 ... Plasma torch,
Reference numeral 9 ... Work piece to be processed, 11 ... Control section, 12 ... Signal conversion circuit, 13 ... Arithmetic processing section, 14 ... Driver circuit, 15 ... Sensor, 16 ... Processing section, 17 ... Camera, 18 ... Slit light projector ,
20a, 20b ... Slit image.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masao Shiotsuki, Narita-cho, Oarai-cho, Higashi-Ibaraki-gun, Ibaraki 4002 Narita-cho, Oarai Engineering Center (72) Inventor Noboru Endo Oarai-cho, Higashi-Ibaraki-gun, Ibaraki Narita-cho 4002 Power Reactor / Nuclear Fuel Development Corporation Oarai Engineering Center (72) Inventor Koichi Iwata 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Incorporated company Meidensha (72) Inventor Koji Ikura 2 Osaki, Shinagawa-ku, Tokyo 1-17 No. 17 inside the company Meidensha (72) Inventor Tsuneetsu Takahashi 2 1-117 Osaki, Shinagawa-ku, Tokyo Inside the company Meidensha (72) Tomonbun Nemoto 2-chome Osaki, Shinagawa-ku, Tokyo No. 17 Stock Company Shameidensha (56) Reference JP 61-203285 (JP, A) JP 60-118907 (JP, A)

Claims (1)

[Claims] 1. A control device for moving a hand head part of a robot to a teaching point on a workpiece to operate the hand head part with respect to the teaching point, the control device being disposed in the vicinity of the hand head part. A projector for projecting a pair of slit light beams on a workpiece, an image pickup means for picking up a pair of slit images by the pair of slit light beams of the projector, and an image detection means for detecting a state of the pair of slit images by the image pickup means. A pair of slits detected by the image detection means, the calculation means calculating the position and orientation between the sensor of the image pickup means and the workpiece based on the detection data by the image detection means. Position correction data and posture data are calculated based on values obtained by converting points in the three-dimensional coordinate system of the image into points on the image of the image pickup means, and the position correction data and posture correction by the calculation means are performed. Scanning control apparatus for a robot, characterized in that the robot hand head portion and so as to modeled after with respect to the surface of the workpiece based on the over data.