JP2012135781A - Method and device for teaching laser machining robot - Google Patents

Abstract

To teach a laser processing robot easily and accurately.
A teaching method for a laser processing robot having a laser scanner for outputting a measurement laser and a processing laser and performing laser processing by irradiating the processing laser onto the workpiece is predetermined with reference to a reference irradiation position on the workpiece. When irradiating the workpiece with the measurement laser based on the reference pattern, the control procedure S4 for controlling the irradiation position of the measurement laser, and the measurement laser emitted from the laser scanner measures the reflected light reflected from the workpiece. The measurement procedure S5 is compared with the reflected light and the reference figure, and the inclination calculation procedure S6 for calculating the inclination of the surface of the workpiece at the reference irradiation position, and the teaching data relating to the posture of the robot is created from the inclination calculated by the inclination calculation unit. And a data creation procedure S7.
[Selection] Figure 3

Description

  The present invention relates to a teaching method and teaching apparatus for a laser processing robot that performs processing such as welding, cutting, and drilling by irradiating a workpiece with laser light.

  2. Description of the Related Art In recent years, a laser welding robot that performs remote welding by irradiating a workpiece with laser light from a remote position has been proposed in response to higher efficiency of a laser oscillator. The laser welding robot is configured by attaching a scanner head that irradiates a laser beam with a variable irradiation direction to the tip of a robot arm. Each axis of the laser welding robot is driven in accordance with teaching data stored in advance in the control device, like other industrial robots. For this reason, teaching work for creating teaching data using an actual machine and a workpiece is performed at the work site (see, for example, Patent Documents 1 and 2).

  Patent Document 1 discloses that when performing a teaching operation, a visible light frame representing a laser light irradiable range is projected from a scanner head onto a work surface. In this case, the teaching worker looks at the projected frame and operates the robot so that the welding point to be irradiated with the laser beam on the workpiece is within the frame, while teaching data on the robot operation path. Can be created. In addition, the teaching operator can create teaching data related to the postures of the robot and the scanner head while operating the robot so that the shape of the frame projected onto the workpiece is a square. As described above, in Patent Document 1, it is intended to support teaching work of an optimum operation path by a teaching worker in a remote welding robot in which the teaching position of the robot and the welding point do not correspond one-to-one.

  In Patent Document 2, when teaching work is performed, a workpiece is irradiated with a plurality of visible light pilot lasers that pass through the outer circumference of the laser beam, and the focus position adjusting means in the scanner head is operated to apply to the workpiece. It is disclosed that the focal length is adjusted so that one pilot laser is projected. In this case, the teaching worker can visually adjust the dot-like image of the pilot laser projected onto the workpiece and adjust the focal length so that the pilot lasers overlap each other. As described above, in Patent Document 2, a laser beam having a long focal length tends to be used, and a remote welding robot in which a large distance is ensured between the laser scanner and the workpiece supports the adjustment of the focal length by the teaching worker. It is planned to do.

JP 2006-346740 A JP 2007-253200 A

  However, in either of Patent Documents 1 and 2, the teaching work depends on the visual observation of the teaching worker and the actual machine operation by the teaching worker, so that the teaching worker is required to have high skill. There is no change. If the skill is insufficient, it is impossible to properly teach the postures of the robot and the scanner head and to properly adjust the focal length of the laser beam. In addition, it may take a long time to perform proper teaching work, which not only increases the burden on the teaching worker, but also allows the actual machine and work to be carried into the work site before the actual welding work can be performed. It will take a long time. This is a problem that also occurs in a robot that performs processing such as cutting and drilling by irradiating a workpiece with a laser beam from a remote position.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to enable easy and accurate teaching work in a laser processing robot that processes a work by irradiating the work with laser light.

  The present invention has been made to achieve the above object, and a laser machining robot teaching method according to the present invention includes a laser scanner that outputs a measurement laser and a machining laser, and irradiates the workpiece with the machining laser. A laser processing robot teaching method for performing laser processing, wherein when the measurement laser is irradiated on the workpiece based on a reference figure predetermined with reference to a reference irradiation position on the workpiece, A control procedure for controlling the irradiation position, a measurement procedure in which the measurement laser emitted from the laser scanner measures the reflected light reflected from the workpiece, the reflected light and the reference figure are compared, and the reference irradiation is performed. An inclination calculation procedure for calculating the inclination of the surface of the workpiece at the position, and from the inclination calculated in the inclination calculation procedure to the posture of the robot It is characterized by having a data creation procedure for creating teaching data.

  According to the above method, the inclination of the workpiece surface is automatically calculated by comparing the reflected light on the workpiece irradiated with the laser and the reference pattern. Then, teaching data is automatically created based on the calculated inclination. For this reason, even if the workpiece and the laser scanner are separated from each other, the posture of the workpiece with respect to the robot can be easily and accurately grasped, and the welding operation can be favorably performed according to the teaching data thus grasped. it can.

  In the control procedure, the irradiation position of the measurement laser is continuously changed when the measurement laser is irradiated on the workpiece based on the reference figure determined in advance with the reference irradiation position on the workpiece as a reference. In the measurement procedure, the locus of the reflected light on the workpiece may be measured. In this case, it is not necessary to provide an optical component for creating an image of a reference shape that is used only during teaching work in the laser scanner, and the locus of the measurement laser can be substituted. It can be simplified.

  The reference figure may be a circle centered on the reference irradiation position on a plane orthogonal to the optical axis of the processing laser.

  The laser scanner includes a first guide laser having the same reference irradiation position as the processing laser, and a second guide laser having an optical axis that intersects with the optical axis of the first guide laser from a location separated from the first guide laser. In the measurement procedure, the reflected light of the first guide laser and the second guide laser is measured, the laser scanner is moved in the optical axis direction of the first guide laser, and the second guide laser is May be moved to the irradiation position of the first guide laser. According to the method, the distance between the laser scanner and the reference irradiation position is adjusted to a desired distance corresponding to the intersection position in the optical axis directions of the first guide laser and the processing laser. For this reason, when performing a welding operation by irradiating a machining laser, the desired distance and the focal length of the machining laser can be adjusted based on the adjusted desired distance, and the machining laser is good for a workpiece. This makes it possible to perform an appropriate welding operation.

  A teaching device for a laser processing robot according to the present invention is a teaching device for a laser processing robot that performs laser processing by irradiating a workpiece with a processing laser, the laser scanner for outputting a measurement laser and the processing laser, and the workpiece When irradiating the workpiece with the measurement laser on the basis of a reference figure determined in advance with reference to the reference irradiation position on the upper side, a control unit that controls the irradiation position of the measurement laser, and the laser beam irradiated from the laser scanner A measuring laser that measures reflected light reflected by the workpiece, an inclination calculating unit that compares the reflected light with the reference figure, and calculates an inclination of the surface of the workpiece at the reference irradiation position; and A data creation unit that creates teaching data related to the posture of the robot from the tilt calculated by the tilt unit. That.

  By using this apparatus, the teaching operation can be performed easily and accurately as in the teaching method described above.

  As described above, according to the present invention, teaching work can be easily and accurately performed in a laser processing robot that irradiates a workpiece with laser light.

It is a conceptual diagram which shows the whole structure of the laser processing robot which concerns on embodiment of this invention. It is a block diagram which shows the structure of the control system of the laser processing robot shown in FIG. It is a flowchart which shows the process sequence of the teaching method performed by the control apparatus shown in FIG. It is explanatory drawing of step S1-S3 of FIG. FIG. 4A is a diagram showing the arrangement relationship between the laser scanner and the workpiece at the time when step S1 is completed, and FIG. 4B is a state in which the laser scanner is moved from the state shown in FIG. FIG. 4C shows a state in which the first guide laser and the second guide laser intersect at the reference irradiation position by further moving the laser scanner from the state shown in FIG. 4B. FIG. It is explanatory drawing of step S4, S5 of FIG. FIG. 5A is a diagram schematically showing the state in which the workpiece is irradiated with the measuring laser in the same manner as in FIG. 4, and FIG. 5B is a diagram illustrating the state shown in FIG. It is a figure shown in figure, It is a figure which shows geometrically the relationship between the reference | standard shape which the laser scanner is going to project, the shape of the image imaged with a camera, and the normal direction of the workpiece | work surface in a reference | standard irradiation position. It is explanatory drawing of the calculation method of the inclination with respect to the reference-axis direction of the image of the measurement laser imaged with the camera. It is explanatory drawing of the calculation method of the inclination angle with respect to the optical axis orthogonal plane in the ellipse major axis direction of the workpiece | work surface. (A)-(c) is explanatory drawing for demonstrating that the inclination-angle of a workpiece | work surface is computable using a known value for a robot control part at the time of finishing step S5.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is the same or respond | corresponds through all the figures, and the detailed description which overlaps is abbreviate | omitted.

(Laser welding robot)
FIG. 1 is a conceptual diagram showing an overall configuration of a laser welding robot 1 according to an embodiment of the present invention. A laser welding robot 1 shown in FIG. 1 is preferably used in equipment for performing work of welding a metal workpiece 10 such as equipment for manufacturing a car body of an automobile, and includes a robot 2, a laser scanner 3, a laser oscillator. 4 and a control device 5. The robot 2 is a multi-axis robot having a plurality of motors 21a to 21f (see FIG. 2). When the plurality of motors 21a to 21f operate, the posture of the robot 2 changes, and the arm tip of the robot 2 moves in various directions. The laser oscillator 4 is a laser light source that generates laser light. The laser light generated by the laser oscillator 4 is guided to the laser scanner 3 through the optical fiber cable 8.

  The laser scanner 3 has a substantially rectangular parallelepiped casing. Since the housing of the laser scanner 3 is fixed to the arm tip of the robot 2, if the position and posture of the arm tip of the robot 2 are determined, the position and posture of the laser scanner 3 are determined. The laser scanner 3 includes first and second emission units 31 and 32 (see FIG. 4) that irradiate laser light outside the housing. The 1st injection part 31 is utilized in order to irradiate the welding laser used at the time of welding operation. The 1st injection part 31 concerning this embodiment is used also for irradiating the measurement laser and the 1st guidance laser used at the time of teaching work. The second injection unit 32 is used to irradiate a second guide laser used during teaching work.

  At least the laser beam irradiated from the first emitting unit 31 has a variable optical axis direction (that is, irradiation direction) and focal length. Therefore, the laser scanner 3 is guided to the first emitting unit 31 and a direction changing mechanism (not shown) for changing the optical axis direction of the laser beam guided to the first emitting unit 31 in the housing. A focus adjustment mechanism (not shown) for changing the focal length of the laser light is provided.

  The control device 5 is connected to the robot 2, the laser scanner 3 and the laser oscillator 4 via communication cables 9a, 9b and 9c, respectively. The control device 5 controls the operation of the laser oscillator 4 and also controls the operations of the robot 2 and the laser scanner 3 in accordance with the pre-stored teaching data, so that remote laser welding by the so-called on-the-fly method is performed on the workpiece 10. Work is done. That is, the laser scanner 3 in which the welding laser having the required wavelength and the required energy density generated by the laser oscillator 4 is located away from the workpiece 10 while moving the arm tip of the robot 2 along the path in an appropriate posture. Irradiation is performed in an appropriate direction at an appropriate timing. At the position irradiated with the welding laser, the workpiece 10 can be altered by the action of the laser beam and the workpiece 10 can be welded. In addition, the welding laser may be irradiated to the position to be welded in a dot shape, or may be irradiated so as to draw a linear or circumferential figure around the position.

  The teaching data includes data relating to the movement path of the robot 2, data relating to the posture of the arm tip on the movement path of the robot 2, data relating to the moving speed on the movement path of the robot 2, and the welding laser irradiated from the laser scanner 3. Data relating to the optical axis direction (that is, data relating to the operation of the above-described direction changing mechanism), data relating to the focal length of the welding laser irradiated from the laser scanner 3 (ie, data relating to the operation of the above-described focus adjusting mechanism), welding laser Data on the reference irradiation position (in other words, the position where the irradiated welding laser should be focused), which is the position to be irradiated on the workpiece surface 10a, data on the output intensity of the welding laser, and the welding laser at the reference irradiation position Data on irradiation time and moving speed of welding laser irradiation position Data, and the like.

  The teaching data is created using the actual workpiece 10 after the laser welding robot 1 is installed in the facility. Note that teaching data created by off-line teaching can be stored in the control device 5 in advance before the laser welding robot 1 is installed. Also in this case, the created teaching data needs to be corrected using an actual work. In the description of the embodiments in this document, unless otherwise specified, the “teaching work” includes a work for creating teaching data on-site and a work for correcting teaching data created by offline teaching on-site.

  Hereinafter, a teaching apparatus and a teaching method according to the present embodiment that contribute to the automation of the teaching work will be described.

(Teaching device)
FIG. 2 is a conceptual diagram showing the configuration of the control system of the laser welding robot 1 shown in FIG. As shown in FIG. 2, the control device 5 includes a robot control unit 51, a laser scanner control unit 52, and a laser oscillator control unit 53. The robot control unit 51 stores teaching data and controls the operation of the motors 21a to 21f of the robot 2 according to the teaching data. The robot control unit 51 stores a control program that instructs a processing procedure of a teaching method to be described later, and controls the operations of the motors 21a to 21f of the robot 2 according to the control program. The robot control unit 51 is communicably connected to the teach pendant 7 operated by the teaching worker, and controls the operation of the motors 21a to 21f of the robot 2 in accordance with a command input by the teaching worker in the teach pendant 7. Moreover, the robot control part 51 has the inclination calculation part 56 and the data preparation part 57 as the function part by being able to run the said control program.

  The laser scanner control unit 52 controls the operation of the laser scanner 3 according to teaching data or a control program stored in the robot control unit 51 or a command input from the teach pendant 7. The laser oscillator control unit 53 controls the operation of the laser oscillator 4. The laser oscillator control unit 53 controls the laser oscillator 4 so as to generate a welding laser having a sufficiently high energy density for welding during welding work. During the teaching operation, the laser oscillator 4 is controlled so as to generate a measurement laser or a guide laser having a sufficiently small energy density so as not to alter the work 10 by the action of the laser light.

  The laser welding robot 1 is provided with a camera 6 at least when performing teaching work. The camera 6 has a photoelectric conversion element such as a CCD as an imaging element, and electronic data (hereinafter referred to as “image data”) related to an image formed on the imaging element is sent to the robot control unit 51. Supply. The robot control unit 51 has an image processing function for processing image data from the camera 6. Note that the image data may include information for specifying the position of each pixel constituting the image sensor, information representing the luminance at each pixel, information representing the color at each pixel, and the like.

  The camera 6 is detachably fixed to the outer surface of the housing of the laser scanner 3 via an attachment at least when teaching work is performed. For this reason, the field of view of the camera 6 is fixed when the laser scanner 3 is used as a reference, and the base of the robot 2 installed on the floor of the facility is used as a reference according to the position and posture of the arm tip of the robot 2. It will move. The camera 6 may be removed from the laser scanner 3 at the stage of completing the teaching operation and performing the welding operation. Thereby, it is possible to prevent the camera 6 from being contaminated by spatter and fumes generated during welding. According to the teaching method described later, the imaging result of the camera 6 may not have a relationship with the absolute position of the laser welding robot 1. Therefore, it is possible to save the trouble of calibrating the camera 6 by measuring the absolute position before performing the teaching work.

  As described above, the teaching device of the laser welding robot 1 includes components of the laser welding robot 1 (ie, the robot 2, the laser scanner 3, the laser oscillator 4, and the control device 5) as a device for performing a welding operation, the camera 6, and the like. The teach pendant 7 is provided. On the contrary, the laser welding robot 1 as an apparatus for performing a welding operation does not necessarily include the camera 6 and the teach pendant 7.

(Laser scanner placement)
FIG. 3 is a flowchart showing the processing procedure of the teaching method executed by the control device 5. 4 to 8 are conceptual diagrams for explaining the processing shown in FIG. As shown in FIG. 3, at the beginning of the teaching method, the robot control unit 51 is arranged so that the laser scanner 3 is placed opposite to the reference irradiation position on the surface of the workpiece 10 at a distance. The motor is controlled (step S1). Here, the reference irradiation position of the workpiece 10 is a position serving as a reference when irradiating a welding laser when performing remote welding. When welding is performed by irradiating the welding laser in a dot shape, the position to be irradiated with the welding laser may be exactly the reference irradiation position. When welding is performed by irradiating a welding laser so as to draw a peripheral figure, the center position of the figure may be the reference irradiation position, or an arbitrary point on the figure is the reference irradiation position. May be. Further, when welding is performed by irradiating a welding laser so as to draw a linear figure, the start point, the intermediate point, or the end point of the figure may be the reference irradiation position.

  In step S1, the position and posture of the arm tip of the robot 2 (that is, the laser scanner 3) so that the reference irradiation position is positioned on the optical axis of the laser light when the first emitting portion 31 is irradiated with the laser light. And the optical axis direction of the laser light are adjusted. This adjustment is executed through the position control of the motor of the robot 2 by the robot control unit 51 and the operation control of the laser scanner 3 by the scanner control unit 52.

  When aligning the optical axis of the laser beam with respect to the reference irradiation position, at least at the time of teaching work, a mark that can be viewed by the teaching operator and / or measured by the camera 6 is attached to the reference irradiation position of the work 10. . Therefore, the laser oscillator control unit 53 controls the laser oscillator 4 so as to generate a guide laser having a wavelength in the visible light range, and the guide laser is emitted from the first emitting unit 31 of the laser scanner 3. In this case, the teaching worker visually observes the reflected light (or image) of the guide laser projected on the workpiece 10 and the robot 2 and / or the laser scanner 3 with the teach pendant 7 so that the reflected light is positioned on the mark. The above alignment can be performed by operating. In addition, while the camera 6 captures the image of the guide laser projected on the workpiece 10 and the image of the mark attached to the reference irradiation position, the robot controller 51 performs two operations based on the image data from the camera 6. You may make it control operation | movement of motor 21a-21f so that an image may overlap. Thereby, the alignment can be automated. If the control device 5 stores teaching data created by off-line teaching, the robot 2 is stopped at a position facing the reference irradiation position according to the teaching data, and then the positioning is performed. The position of the arm tip of the robot 2 and / or the optical axis direction of the guide laser is finely adjusted to perform the above.

(Adjusting the distance between the laser scanner and the workpiece)
After the laser scanner 3 is arranged at a distance from the surface of the workpiece 10 as described above, as shown in FIG. 4A, the first guide laser L1 is emitted from the first emission unit 31 and the second emission is performed. The second guide laser L2 is irradiated from the unit 32, and images I _L1 and I _L2 of the first and second guide lasers L1 and L2 projected on the workpiece 10 are captured by the camera 6. Further, the robot control unit 51 determines whether the images I _L1 and I _{L2 of} the first and second guide lasers L1 and L2 intersect at the reference irradiation position p based on the image data from the camera 6 ( Step S2). The first guide laser L1 has the same optical axis direction as the welding laser used during welding work. Note that the distance Z _f from the first injection unit 31 to the intersection f, may be the same or different in the first guide laser and welding laser. Here, for simplification of description, the description will be made assuming that they are the same. The second guide laser L2 has an optical axis that is inclined with respect to the optical axis of the first guide laser L1, and is optically designed to intersect the first guide laser L1.

  The process of step S2 will be described in more detail. In step S 1 prior to step S 2, the position and posture of the arm tip and the optical axis direction of the laser light emitted from the first emitting unit 31 are adjusted. Therefore, the irradiation from the first emitting unit 31 is also performed in step S 2. The first guiding laser L1 is projected onto the reference irradiation position p. However, since the position of the intersection f is not adjusted in step S1 (it is not necessary because automatic adjustment is performed in step S2), the intersection f of the first guide laser L1 is located at the reference irradiation position p. Probability is very low. Even when the teaching data is created by off-line teaching, the intersection f may not be located at the reference irradiation position p due to an installation error of the workpiece 10 or the like.

As shown in FIG. 4A, if the intersection f is not located at the reference irradiation position p, the second guide laser L2 is projected on the surface of the workpiece 10 at a position away from the reference irradiation position p. On the other hand, since the camera 6 is arranged and optically designed so that the periphery of the reference irradiation position p can be accommodated in the field of view, the camera 6 projects the first guide laser L1 projected to the reference irradiation position p. And a point image of the second guide laser L2 projected at a position distant from the reference irradiation position p. FIG. 4A illustrates the case where the intersection f is located on the side away from the laser scanner 3 when viewed from the reference irradiation position p (Z ₀ <Z _f ), but in the opposite case Since the irradiated second guide laser L2 travels to the right side of the paper before the reference irradiation position p before reaching the surface of the workpiece 10, the first and second guide lasers L1 and L2 are separated from each other on the workpiece surface 10a. Are projected at two positions.

Among the pixels constituting the image sensor of the camera 6, the luminance of the pixels on which the laser light images I _L1 and I _L2 are formed is much higher than that of the pixels on which the images are not formed. Therefore, the robot control unit 51 refers to the luminance information included in the image data from the camera 6 to identify the location where the laser light images I _L1 and I _L2 are formed, and the two images I _L1 , It calculates the distance d between the I _L2. The distance d calculated here does not need to be an actual distance between the two images I _L1 and I _L2 on the surface of the workpiece 10, and may be a distance within the field of view of the camera 6.

  The robot control unit 51 refers to the luminance and color information included in the image data from the camera 6 and determines whether or not the two point images are separated beyond a predetermined allowable range. Thereby, it is determined whether or not the images of the first and second guide lasers L1 and L2 intersect at the reference irradiation position p.

  If the intersection f is located at the reference irradiation position p, the second guide laser L2 is also projected onto the reference irradiation position p as shown in FIG. One point-like image projected on the screen is captured. Therefore, the first guide laser L1 is a visible light laser of a first color (for example, red), the second guide laser L2 is a visible light laser of a second color (for example, green) different from the first color, and when these intersect, It is preferable to determine the wavelengths of the first guide laser L1 and the second guide laser L2 so that the third color (for example, orange) is different from both the first color and the second color at the position. Then, the robot controller 51 determines that there is only one image that is estimated to be a laser beam image even if the image data from the camera 6 is referred to in the process of step S2 immediately after step S1. In this case, it is possible to satisfactorily recognize whether or not the two laser beams are overlapped based on the information relating to the color of the image.

  When it is determined that they do not intersect (S2: NO), the robot control unit 51 moves the arm tip and the laser scanner 3 in the optical axis direction of the first guide laser L1 (step S3). Then, it is determined again whether or not they intersect (step S2). While not intersecting (S2: NO), the laser scanner 3 is continuously moved (step S3).

  FIG. 4B shows the position and posture of the arm tip and the laser scanner 3 before the process of step S3 (see the two-dot chain line), and the position of the arm tip and the laser scanner 3 after the process of step S3. And the posture (see solid line). As shown in FIG. 4B, in step S3, the robot control unit 51 moves the laser scanner 3 in the optical axis direction of the first guide laser L1 while maintaining the posture of the arm tip and the laser scanner 3. The operation of the motor of the robot 2 is controlled so that the direction of the optical axis of the first guide laser L1 relative to the workpiece 10 is not changed. Thereby, the state where the reference irradiation position p is located on the optical axis of the first guide laser L1 can be maintained.

When the laser scanner 3 moves in this way, the position at which the second guide laser L2 is projected onto the surface of the workpiece 10 approaches or moves away from the reference irradiation position p in accordance with the moving direction. FIG. 4B illustrates a case where the laser scanner 3 is moved so that the intersection f approaches the reference irradiation position p. In this case, the position where the second guide laser L2 is projected is the reference irradiation position p. Get closer to. Each time the laser scanner 3 is moved by a minute distance, the robot control unit 51 performs a repetitive process of performing a determination process. As a result, as shown in FIG. L2 can be projected onto the reference irradiation position p. At this time, the robot control unit 51 determines that the images I _L1 and I _{L2 of} the first and second guide lasers L1 and L2 intersect each other. If this determination is made (S2: YES), the laser is omitted although not shown. The movement of the scanner 3 stops.

Here, as shown in FIG. 4B, when it is known in advance that the periphery of the reference irradiation position p is a flat surface or can be approximated to a flat surface, the above-described repetitive processing can be simplified. . That is, in such a case, the amount of movement of the laser scanner 3 is proportional to the movement amount of the image I _L2 of the second guide laser L2 in the field of view of the camera 6. If attention is paid to this, after moving the laser scanner 3 slightly after step S1, the amount of movement Z of the laser scanner 3 necessary for positioning the intersection f at the reference irradiation position p is as follows. It is calculated | required from Formula (1).

Here, Delta] z is the moving amount of the laser scanner 3 which is slightly moved after finishing step S1, [Delta] d is, the first guide image I _L2 of the second guide laser L2 in the case where the laser scanner 3 is moved by the movement amount Delta] z The relative movement amount d of the laser L1 with respect to the image I _L1 is a distance between the two images I _L1 and I _L2 when step S1 described above is finished. The relative movement amount Δd can be measured by subtracting the distance between the two images I _L1 and I _L2 after the laser scanner 3 has moved by the movement amount Δz from the distance d.

Then, after finishing step S1, the laser scanner 3 is moved by a slight movement amount Δd, the movement amount Z is calculated according to the above equation (1), and the laser scanner 3 is moved by the calculated movement amount Z. positioning the image I _L2 of the second guide laser L2 to the reference irradiation position p, i.e. it is possible to locate the intersection f the reference irradiation position p. While the laser scanner 3 is moved by the movement amount Z, image processing can be omitted, and thus the moving speed of the laser scanner 3 can be increased. Therefore, the intersection f is positioned at the reference irradiation position p. The time required to do this is shortened.

(Inclination calculation)
When the robot controller 51 determines that the images I _L1 and I _{L2 of} the first and second guide lasers L1 and L2 intersect at the reference irradiation position p and the movement of the laser scanner 3 stops (S2: YES). The scanner control unit 52 irradiates the measurement laser L from the first emitting unit 31 and projects the measurement laser L onto the surface of the workpiece 10, and a reference figure having a predetermined reference shape is formed on the surface of the workpiece 10 by the measurement laser L. The operation of the laser scanner 3 is controlled so as to be drawn (step S4), and a graphic image of the measurement laser L actually projected on the workpiece surface 10a is captured by the camera 6 (step S5).

  Here, the reference shape is a plane in which the periphery of the reference irradiation position p in the surface 10a of the workpiece 10 is orthogonal to the optical axis A1 of the first guide laser (hereinafter simply referred to as “optical axis orthogonal plane”). Is a shape to be projected around the reference irradiation position p, and preferably a closed loop shape (for example, a circular shape or a polygonal shape). If the periphery of the reference irradiation position p is tilted with respect to the plane orthogonal to the optical axis, the reference shape is distorted on the surface of the workpiece 10 even if the measurement laser L is irradiated to draw the reference figure of the reference shape. A figure with the wrong shape is projected. In the processing after step S4, paying attention to this, the inclination angle with respect to the optical axis orthogonal plane around the reference irradiation position p of the surface of the workpiece 10, in other words, the normal direction of the surface of the workpiece 10 at the reference irradiation position p. Is calculated.

  In step S4, in order to project a figure onto the surface of the workpiece 10 with the measuring laser L, the irradiation position of the measuring laser L (that is, the optical axis direction) so as to trace the shape to be projected on the optical axis orthogonal plane. ) Can be changed continuously at high speed. In other words, the measurement laser L traveling from the first emitting portion 31 toward the workpiece 10 draws the side surface of the cone having the reference figure on the plane orthogonal to the optical axis as the bottom and the first emitting portion 31 as the apex. Thus, the optical axis direction of the measurement laser L may be changed continuously at a high speed. This high speed means that when the measurement laser L projected on the surface of the workpiece 10 is imaged by the camera 6 in step S5, the trace of the figure corresponding to the reference shape becomes an afterimage of the measurement laser L on the image sensor of the camera 6. The speed is high enough to form an image.

  In FIG. 5B, the reference figure of the reference shape RF that was supposed to be projected onto the surface 10a of the workpiece 10 for control is indicated by a dotted line, and is actually projected onto the surface 10a of the workpiece 10 and captured by the camera 6. A figure of the shape MF is indicated by a solid line. The reference shape RF according to the present embodiment is a perfect circle having a radius r centered on the reference irradiation position p in the plane orthogonal to the optical axis. For this reason, in step S4, the optical axis direction of the measurement laser L is continuously changed at a high speed so that the side surface of the cone is drawn by the measurement laser L irradiated from the first emitting unit 31 (FIG. 5). (B) shows the generatrix of the cone to be drawn with the measuring laser L). When the reference shape RF is a perfect circle, if the surface 10a of the workpiece 10 is tilted, the measurement shape MF is an ellipse obtained by distorting the perfect circle.

  When the figure of the measurement shape is captured by the camera 6 in this way, the robot control unit 51 compares the reference shape with the measurement shape, and the inclination of the workpiece surface 10a at the reference irradiation position p, more specifically, the workpiece surface. The normal direction of 10a is calculated (step S6).

With reference to FIGS. 5B and 6, when calculating the normal direction, first, an inclination angle θ ₁ with respect to the reference axis direction of the major axis direction of the ellipse that is the measurement shape MF is calculated. Here, the reference axis direction is a direction parallel to a certain axis forming a coordinate system set in the teaching device of the laser welding robot 1. The certain axis may be an axis forming a robot coordinate system or a laser scanner coordinate system, or may be any one of an X axis and a Y axis constituting a two-dimensional orthogonal coordinate system measured by the camera 6. Good. When the direction parallel to one of the X axis and the Y axis is the reference axis direction, the inclination angle of the elliptical long axis direction with respect to the reference axis direction around the reference irradiation position p is θ ₁ . The tilt angle θ ₁ when the direction parallel to the X axis is the reference axis direction can be obtained according to the following equation (2).

Here, x is the length of the reference axis direction component in the field of view of the camera 6 among the distances between the reference irradiation position p, the measurement shape MF, and the intersection A of the elliptical long axis, and y is the distance of the distance Of these, the length of the component in the direction orthogonal to the reference axis direction in the field of view of the camera 6 is shown. In calculating the inclination angle θ ₁ , it is not necessary to obtain accurate values of x and y (that is, actual values on the workpiece surface 10a), and it is sufficient if the ratio of x to y can be obtained.

Since the robot control unit 51 can grasp the positional relationship between the camera coordinate system and the robot coordinate system, the coordinates of the reference irradiation position p in the robot coordinate system can be obtained based on the inclination angle θ ₁ in this way. .

When the direction parallel to the Y axis perpendicular to the X axis is the reference axis direction, the calculated tilt angle is 90−θ ₁ [deg]. Therefore, the robot control unit 51 applies the axis on the side where the inclination angle is smaller among the X axis and the Y axis, that is, the axis on the side where the inclination angle is 45 degrees or less, in the reference axis direction. In this way, the correction amount is at most 45 degrees, and the posture variation can be suppressed as much as possible.

When coordinate correction is performed in consideration of the inclination angle θ ₁ in this manner, the inclination angle θ ₂ is geometrically defined in a two-dimensional plane in which the workpiece surface 10a is represented by a line along the ellipse major axis direction, as shown in FIG. Can be calculated scientifically. For convenience of description of this calculation method, reference numerals A to H are attached to feature points. “Point A” is the position of the first emitting portion 31, “Point E” is the reference irradiation position, and “Point F” is a point in the direction of the line segment AE among the intersections of the cone generating line drawn by the measurement laser L and the workpiece surface 10 a. An intersection on the side close to A, “point G” is an intersection on the far side in the direction of the line segment AE opposite to the point F, and “point D” is a straight line and line segment AG passing through the point E and orthogonal to the line segment AE (Point B) is an intersection of a straight line passing through the point F and parallel to the line segment ED and the line segment AG, and “point C”. Is the intersection of the line segment FB and the line segment AE, and “Point H” is the intersection of the half line DE and the line passing through the point F and orthogonal to the half line DE.

  Here, at the time when step S5 is completed, the robot control unit 51 can handle the relationships expressed by the following equations (3) to (5) as known.

Regarding the above equation (3), the line segment AE is the value adjusted in step S1. Regarding the above equation (4), the line segment DE is a value determined in advance in the control program that instructs the processing procedure of the teaching method. Regarding the above formula (5), the ratio of the line segment GE to the line segment EF can be measured from the data relating to the image captured by the camera 6 in step S5. The inclination angle θ ₂ can be calculated using only values Z _f , r, and K known to the robot control unit 51. Hereinafter, this point will be described with reference to FIG.

  As shown in FIG. 8A, the triangle FBG has a similar relationship with the triangle EDG due to a biphasic phase or the like. Therefore, the length r ′ of the line segment BC is calculated according to the following equation (6) using r and K.

As shown in FIG. 8B, the triangle ABC is similar to the triangle ADE due to a binary phase or the like. Therefore, the length Z ₁ of the line segment AC is calculated according to the following equation (7) using Z _f and K. Thereby, the length _{Z 2} of the line segment FH is calculated according to the following equation (8) using a _{Z f} and K.

As shown in FIG. 8C, when attention is paid to the right triangle FEH, the length of the side EH is r ′ and the length of the side HF is Z ₂ , so that the inclination angle θ ₂ is Z _f , r. And K are calculated according to the following equation (9).

Thus, the inclination angle θ ₂ can be calculated using the values Z _f , r, and K known to the robot control unit 51. Moreover, these values are values that can be grasped by the robot controller 51 even if the camera 6 does not measure the absolute position of the laser welding robot 1. Therefore, it is not necessary to calibrate the camera 6 to calculate the inclination angle theta _2.

(Determination of teaching data)
As described above, the distance Z _f from the first emitting unit 31 to the reference irradiation position p, the inclination angle θ ₁ in the elliptical long axis direction of the measurement shape with respect to the reference axis direction, and the optical axis orthogonal to the workpiece surface 10 at the reference irradiation position p. When the tilt angle θ _{2 with} respect to the plane (that is, the normal direction of the workpiece surface at the reference irradiation position p) is calculated, the robot adjusted in steps S2 and S3 based on these calculated values Z _f , θ ₁ , and θ _2. The position and orientation data of the arm tip 2 and the laser scanner 3 and the data of the reference irradiation position p are corrected, and the corrected data is determined as teaching data (step S7).

  Thereby, when performing a welding operation, the optical axis of the welding laser can be tilted toward the reference irradiation position p by a required angle with respect to the normal direction of the workpiece surface at the reference irradiation position p. The angle includes 0 degree and includes a concept in which the optical axis and the normal line coincide. Further, the welding laser can be focused at the reference irradiation position p. Therefore, the welding laser can be optimally applied to the workpiece 10, and the welding operation can be performed satisfactorily. In addition, teaching data for realizing such a welding operation is automated using the camera 6. For this reason, teaching work can be performed easily and accurately.

  The embodiment of the present invention has been described above, but the configuration of the apparatus and the procedure of the method can be appropriately changed within the scope of the present invention.

  For example, three or more guide lasers may be irradiated in steps S2 and S3. In step S4, the reference shape is not limited to a perfect circle but may be other shapes such as a square frame. In this case, the calculation formula of the tilt angle in step S5 is changed as appropriate. Further, the teaching apparatus and teaching method of the present invention are not limited to a robot that performs remote welding, and can be suitably applied to a robot that performs other laser processing such as cutting and drilling of a workpiece.

  INDUSTRIAL APPLICABILITY The present invention has an advantageous effect that teaching work can be performed easily and accurately, and is useful when applied to a laser welding robot that performs remote welding work.

DESCRIPTION OF SYMBOLS 1 Laser welding robot 2 Robot 3 Laser scanner 4 Laser oscillator 5 Control apparatus 6 Camera 10 Workpiece | work 31 1st injection | emission part 32 2nd injection | emission part L1 1st guide laser L2 2nd guide laser L Measurement laser A1 (Welding laser and 1st guide Laser optical axis p Reference irradiation position f Intersection Z f (welding laser and first guide laser) intersection Z _f (in the optical axis direction from the first emitting part to the focal point) Distance θ ₁ First tilt angle θ ₂ Second tilt angle

Claims (8)

A laser processing robot having a laser scanner that outputs a measurement laser and a processing laser, and irradiating the workpiece with the processing laser to perform laser processing,
A control procedure for controlling the irradiation position of the measurement laser when irradiating the measurement laser on the workpiece based on a reference figure predetermined with reference to a reference irradiation position on the workpiece;
A measurement procedure in which the measurement laser emitted from the laser scanner measures reflected light reflected from the workpiece;
An inclination calculation procedure for comparing the reflected light with the reference graphic and calculating an inclination of the surface of the workpiece at the reference irradiation position;
And a data creating procedure for creating teaching data relating to the posture of the robot from the tilt calculated in the tilt calculating procedure. In the control procedure, the irradiation position of the measurement laser is continuously changed when the measurement laser is irradiated on the workpiece based on the reference figure determined in advance with the reference irradiation position on the workpiece as a reference. Done
The laser processing robot teaching method according to claim 1, wherein in the measurement procedure, a locus of the reflected light on the workpiece is measured.   The laser processing robot teaching method according to claim 1, wherein the reference graphic is a circle centered on the reference irradiation position in a plane orthogonal to the optical axis of the processing laser. The laser scanner includes a first guide laser having the same reference irradiation position as the processing laser, and a second guide laser having an optical axis that intersects with the optical axis of the first guide laser from a location separated from the first guide laser. And
In the measurement procedure, the reflected light of the first guide laser and the second guide laser is measured, the laser scanner is moved in the optical axis direction of the first guide laser, and the irradiation position of the second guide laser is The method for teaching a laser processing robot according to claim 1, wherein the laser beam is moved to the irradiation position of the first guide laser. A laser processing robot teaching apparatus that performs laser processing by irradiating a workpiece with a processing laser,
A laser scanner for outputting a measurement laser and the processing laser;
A control unit that controls the irradiation position of the measurement laser when irradiating the measurement laser on the work based on a reference figure predetermined with reference to the reference irradiation position on the work;
The measurement laser emitted from the laser scanner includes a measurement unit that measures reflected light reflected from the workpiece,
An inclination calculator that compares the reflected light with the reference graphic and calculates the inclination of the surface of the workpiece at the reference irradiation position;
A teaching device for a laser processing robot, comprising: a data creation unit that creates teaching data related to the posture of the robot from the tilt calculated by the tilt unit.   The control unit continuously changes the irradiation position of the measurement laser when irradiating the workpiece with the measurement laser based on the reference figure predetermined with the reference irradiation position on the workpiece as a reference. 6. The teaching device for a laser processing robot according to claim 5, wherein the measuring unit measures a locus of the reflected light on the workpiece.   The laser processing robot teaching apparatus according to claim 5 or 6, wherein the reference graphic is a circle centered on the reference irradiation position on a plane orthogonal to the optical axis of the processing laser. The laser scanner includes a first guide laser having the same reference irradiation position as the processing laser, and a second guide laser having an optical axis that intersects with the optical axis of the first guide laser from a location separated from the first guide laser. And
The measuring unit measures reflected light of the first guide laser and the second guide laser;
8. The control unit according to claim 5, wherein the control unit moves the laser scanner in an optical axis direction of the first guide laser to move an irradiation position of the second guide laser to an irradiation position of the first guide laser. 9. The teaching apparatus of the laser processing robot of any one of Claims 1.

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