Teaching device and teaching method for laser machining

Abstract

The present application provides a teaching device capable of avoiding twisting of an optical fiber connected to an electric detection scanner beyond an allowable range. In a teaching device (60) for teaching a robot of a laser processing system, there are provided: a path decision unit (162) that decides a movement path of the robot based on positions of a plurality of processing points set on an object; a simulation execution unit (163) that executes movement simulation of the robot in accordance with the decided movement path; a twist amount evaluation unit (164) that obtains a twist amount of the optical fiber by simulating behavior of the optical fiber in accordance with movement of the robot based on the movement simulation, and evaluates the twist amount by comparing the twist amount with a prescribed allowable range; and a robot posture change unit (165) that changes a posture of the robot in such a manner that the twist amount becomes smaller for movement of the robot for which the twist amount exceeds the prescribed allowable range.

Description

TECHNICAL FIELD

[0001] The present application relates to a teaching device and a teaching method for laser processing using a robot to teach a laser processing system. BACKGROUND

[0002] A laser processing system that irradiates laser light from a processing head mounted on the tip of an arm of a robot to perform welding or the like on a workpiece is proposed (for example, Patent Documents 1 to 5).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-35404

[0006] Patent Document 2: Japanese Patent Application Publication No. 2006-344052

[0007] Patent Document 3: Japanese Patent Application Publication No. 2018-086711

[0008] Patent Document 4: Japanese Patent Application Publication No. 2006-281304

[0009] Patent Document 5: Japanese Patent Application Publication No. 2007-21550 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] In a laser processing system that uses an electric potential detecting scanner as a laser processing head, a teaching device generates a robot motion path in such a manner that the dots are within the irradiation range of the electric potential detecting scanner mounted on the robot, based on the arrangement of the dots. In the case where the robot is caused to move in accordance with the motion path generated as such, depending on the posture of the electric potential detecting scanner, the optical fiber connected to the electric potential detecting scanner can sometimes be twisted beyond the allowable range.

[0012] SOLUTION TO THE PROBLEM

[0013] One embodiment of the present disclosure is a teaching device for teaching an action of a robot of a laser processing system including a laser processing head to which an optical fiber is connected and the robot that moves the laser processing head, the teaching device including: a path decision section that decides a movement path of the robot based on positions of a plurality of processing points set on an object; a simulation execution section that executes a movement simulation of the robot in accordance with the decided movement path; a twist amount evaluation section that evaluates a twist amount of the optical fiber by simulating a behavior of the optical fiber in accordance with a movement of the robot based on the movement simulation, by comparing the twist amount with a prescribed allowable range; and a robot posture change section that changes a posture of the robot in a manner that reduces the twist amount for the movement of the robot in which the twist amount exceeds the prescribed allowable range.

[0014] Another embodiment of the present disclosure is a teaching method for teaching an action of a robot of a laser processing system including a laser processing head to which an optical fiber is connected and the robot that moves the laser processing head, in the teaching method, a movement path of the robot is decided based on positions of a plurality of processing points set on an object, a movement simulation of the robot is executed in accordance with the decided movement path, a twist amount of the optical fiber is found by simulating a behavior of the optical fiber in accordance with a movement of the robot based on the movement simulation, the twist amount is evaluated by comparing the twist amount with a prescribed allowable range, and a posture of the robot is changed in a manner that reduces the twist amount for the movement of the robot in which the twist amount exceeds the prescribed allowable range.

[0015] Effects of Invention

[0016] According to the above-described structure, teaching in the laser processing system can be performed in a manner that the twist of the optical fiber is within the allowable range.

[0017] These and other objects, features and advantages of the present application will become more apparent from the following detailed description of certain exemplary embodiments of the present application taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 FIG. 1 is a diagram showing an overall configuration of a laser processing system including a laser processing teaching device according to one embodiment.

[0019] Figure 2 FIG. 3 is a diagram showing functional configurations of a laser processing teaching device, a robot control device, and a scanner.

[0020] Figure 3 FIG. 6 is a flowchart showing a movement program creation process.

[0021] Figure 4 It is a flowchart representing the generation of motion paths and the determination of motion speed.

[0022] Figure 5 It is a diagram used to illustrate the grouping and path determination of the dot group.

[0023] Figure 6A It is a diagram representing the state of the robot moving along the edge of the illumination range.

[0024] Figure 6B This is a diagram representing a state where the robot's direction of movement is not along the illumination range.

[0025] Figure 7 This represents an example of a situation where the robot's posture is determined by how its direction of movement is along the edge of the scanner's illumination range.

[0026] Figure 8 This is a perspective view showing an example of a line body model used in the behavioral simulation of line bodies.

[0027] Figure 9 This is an example image showing lines and points of interest.

[0028] Figure 10 This is a diagram illustrating the calculation process of torsion in the behavioral simulation of a line body.

[0029] Figure 11 This is a diagram illustrating the change in the robot's posture used to eliminate torsion. Detailed Implementation

[0030] Next, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same constituent parts or functional parts. The scale of these drawings has been appropriately altered for ease of understanding. Furthermore, the embodiments shown in the drawings are examples for carrying out the invention, and the invention is not limited to the illustrated embodiments.

[0031] Figure 1 This is an overall structural diagram of a laser processing system 100 including a laser processing teaching device 60 according to one embodiment. The laser processing system 100 is configured as a so-called coordinated remote laser processing system, in which a laser scanning head (hereinafter simply referred to as a scanner) 90, mounted on a predetermined movable part (in this embodiment, the forearm end) of a robot 110, is moved while laser scanning is performed to process various processing points on the workpiece W. Figure 1 In the structural example, the laser processing system 100 includes a robot 110, a robot control device 70 for controlling the robot 110, a laser oscillator 80, and a laser processing teaching device 60.Figure 1 In the structural example shown in FIG. 1, the robot 110 is a vertical multi-joint robot, but other types of robots can also be used. In addition, a laser scanning device other than an electric potential detecting scanner can also be used. The scanner 90 has a function of scanning laser light delivered from the laser oscillator 80 via the optical fiber 81 in the XY direction by driving a mirror, and a function of moving a laser spot in the Z direction by driving a lens in the Z direction.

[0032] The optical fiber 81 is connected to the central portion of the upper surface 90a of the scanner 90 in a state in which the connection end portion 81a connected to the scanner 90 is substantially perpendicular with respect to the upper surface 90a of the scanner 90.

[0033] The laser processing teaching device 60 is a programming device that generates an action program of the robot 110 and the scanner 90 offline. The laser processing teaching device 60 can also have a structure of a general PC having a CPU, a ROM, a RAM, a hard disk, an input device, a display device, a network interface, and the like as hardware constituent elements. As the laser processing teaching device 60, various information processing devices such as a desktop PC, a notebook PC, a portable information terminal, and the like can be used. In the structural example shown in FIG. 1, the laser processing teaching device 60 is connected to the robot control device 70 via a network, and an action program of the robot 110 and the scanner 90 created by the laser processing teaching device 60 can be transmitted from the laser processing teaching device 60 to the robot control device 70 via the network. Figure 1

[0034] The robot control device 70 has an action control section 71 that controls the action of the robot 110 in accordance with the action program. The robot control device 70 can also have a structure of a general computer having a CPU, a ROM, a RAM, a storage device, and the like. The action program of the scanner 90 generated by the laser processing teaching device 60 is transmitted from the laser processing teaching device 60 to the control section 91 of the scanner 90 via the robot control device 70. The control section 91 of the scanner 90 can act in accordance with the loaded action program. The control section 91 of the scanner 90 can also have a structure of a general computer having a CPU, a ROM, a RAM, a storage device, and the like.

[0035] The laser processing system 100 can perform various laser processing such as welding, cutting, and the like. Hereinafter, the case in which the laser processing system 100 performs welding will be described. As described in detail below, the laser processing teaching device 60, in the creation process of an action program in which a dot group serving as a welding object is welded, corrects the posture of the robot 110 so that the twist of the optical fiber 81 does not occur by performing action simulation of the robot 110 and evaluating the twist amount of the optical fiber 81 accompanying the movement of the robot 110.

[0036] Figure 2 ​is a diagram showing functional blocks of the laser processing teaching device 60, the robot control device 70, and the scanner 90. Figure 2 The functional blocks of the laser processing teaching device 60 shown can be realized by execution of software by the CPU 61 of the laser processing teaching device 60, or by dedicated hardware such as an ASIC (Application Specific Integrated Circuit). Figure 2 As shown, the laser processing teaching device 60 has a data input section 161, a path decision section 162, a simulation execution section 163, a twist amount evaluation section 164, a robot posture change section 165, and an action program creation section 166.

[0037] The data input section 161 acquires various data including model data of a dot group as a welding object, welding time of each dot, a welding pattern, a robot 110, a workpiece W, and the like, which are required for an action program creation process. These various data can be pre-stored in a storage device within the laser processing teaching device 60, or can be data input to the laser processing teaching device 60 via an operation section. Alternatively, the various data can be input to the laser processing teaching device 60 from an external device via a network.

[0038] The path decision section 162 groups the dot group acquired by the data input section 161, decides an action path through each group, and decides an action speed in a manner that enables welding of all the dots as a welding object and shortening of a cycle time.

[0039] The simulation execution section 163 executes action simulation of the robot 110 using the action path and the action speed decided by the path decision section 162.

[0040] The twist amount evaluation section 164 calculates a twist amount of the optical fiber 81 by simulating behavior of the optical fiber 81 in accordance with movement of the robot 110 based on the action simulation, and evaluates the twist amount by comparing the twist amount with a prescribed allowable range.

[0041] The robot posture change section 165 changes a posture of the robot 110 in a manner that makes the twist amount smaller, with respect to an action of the robot 110 for which the twist amount exceeds the prescribed allowable range.

[0042] The action program creation section 166 creates an action program of the robot 110 and the scanner 90 using data of the action path, the action speed, welding period of each dot, and the like, which are adjusted variously. Thereby, an action path (action program) of the robot 110 and an action program of the scanner 90 are generated, which execute a prescribed welding work in a manner that enables the twist amount of the optical fiber 81 to be within the allowable range.

[0043] Figure 3 is a flowchart showing an action program creation process of generating an action program for performing a prescribed welding operation while the twist amount of the optical fiber 81 is within an allowable range. Figure 3 The action program creation process of the laser processing teaching device 60 is executed under the control of the CPU 61. Further, it is assumed that various data required for the action program creation process, including model data of the dot group to be welded, the welding time of each dot, the welding pattern, the workpiece W, and the like, are input via the data input section 161 at the start of the action program creation process.

[0044] When the action program creation process is started, first, the laser processing teaching device 60 (path decision section 162) performs generation of the action path of the robot 110 and a process for deciding the action speed (step S11). Figure 4 is a flowchart showing the generation of the action path and the decision process of the action speed in step S11. As an example, it is assumed that the action path is generated for the dot group 201-215 shown in FIG. 8. First, in step S21, the dot group 201-215 is grouped into temporary dot groups. Here, one group defines a plurality of dots to be welded during the period in which the robot 110 acts by one action command. Within one group, the robot 110 acts by one action command, and during this period, the scanner 90 performs a scanning action to weld each dot belonging to the group. In one action command, the robot 110 acts at a constant speed in a straight line. Here, as an example, it is assumed that the dot group 201-215 is temporarily divided into three dot groups G1-G3. Figure 5

[0045] In step S22, the path of the robot 110 passing through the center of each group G1-G3 is decided. The straight line passing through the center of the dot group is found, for example, by the least squares method. As an example, description is made with respect to the group G1, the path R1 is found as a straight line in which the sum of the squares of the distances from each dot 201-205 to the path R1 is the smallest. Further, the dot positions are positions in a three-dimensional space, and thus the dots 201-205 are actually distributed in the three-dimensional space, but the plane of the position obtained by averaging the dot positions is defined, and the above-described path decision is performed by regarding each dot as existing at the position obtained by projecting each dot onto the plane. The plane of the position obtained by averaging the dot positions can be found, for example, by the least squares method or Newell's algorithm. It is assumed that the paths R1, R2, R3 are decided as the paths of the dot groups G1, G2, G3, respectively, by the process in step S22. Further, the path can also be decided as a path in which the foot of the perpendicular line falling from the irradiation position of the laser light to the plane defining the dot group moves on the plane.

[0046] ​Next, in step S23, it is checked whether or not each dot is within the operation range (irradiation range) of the scanner 90 for each dot group. The checking of this step S23 is performed, for example, with respect to the dot group G1, based on whether or not the distance from each dot 201-205 to the path R1 is within the operation range of the scanner 90. In the case where a dot is found to be outside the operation range of the scanner 90 (S23: No), the grouping is performed again (step S21).

[0047] Next, in step S24, the movement order between dot groups and the dot order within a dot group are optimized. Here, the movement order between dot groups and the dot order within a dot group are determined in such a manner that the total movement distance between dot groups becomes the minimum. As a method of determining the movement order that minimizes the total movement distance between dot groups, various methods known in this field for solving the so-called traveling salesman problem can be used. The dot groups G1-G3 and the paths R1-R3 are determined with respect to the dot groups 201-215 as shown in FIG. 2 by the above processing. Further, as a method of determining the movement path with respect to the dot groups, various methods known in this field (for example, the method of determining the movement path described in Japanese Patent Application Publication No. 2020-35404) can be applied. Figure 5

[0048] Next, in step S25, the operation speed of the robot 110 is determined. The determination of the operation speed of the robot 110 can also be performed by the following processes.

[0049] (Process 1) Determine a temporary operation speed with respect to each dot group.

[0050] (Process 2) Perform operation simulation of the robot using the determined path and operation speed.

[0051] (Process 3) Calculate the period during which each dot can be welded on the operation path of the robot

[0052] (Process 4) Determine the position and time at which each dot is welded.

[0053] (Process 5) Optimize the operation speed.

[0054] The processes are described in detail. In process 1, the temporary speed can be uniformly set to a low speed that is considered to be able to weld the dots of each dot group without problems with respect to all dot groups. Alternatively, a representative speed based on an empirical value can be uniformly set with respect to each dot group.

[0055] ​Next, in process 2, the motion simulation of the robot 110 is performed using the path (paths R1-R3) and the temporary motion speed determined as described above. By the execution of the motion simulation, the position data of each interpolation cycle of the robot (hereinafter also referred to as a motion path) is acquired.

[0056] Next, in process 3, the period corresponding to the range in which each dot can be welded on the motion path of the robot 110 (hereinafter referred to as a weldable period) is calculated using the motion path of the robot 110 obtained by the motion simulation of the robot 110. Specifically, first, the position of the scanner 90 attached to the arm tip of the robot 110 (specifically, for example, the position of a condensing lens within the scanner 90) is found based on the position of the robot 110 on the motion path, and the path of the laser light connecting the position of the scanner 90 and the position of the dot is found. At this time, it is also possible to determine that welding can be performed for the path of the laser light when the following conditions are satisfied:

[0057] (1) The path of the laser light does not interfere with the workpiece or the jig;

[0058] (2) The path of the laser light is within the action range of the scanner;

[0059] (3) The angle (irradiation angle) formed by the normal direction of the workpiece at the dot position and the laser light is within a prescribed allowable range.

[0060] Furthermore, the period corresponding to the range in which the path of the laser light is continuously determined to be weldable on the motion path is the weldable period for each dot.

[0061] Next, in process 4, the position and time at which each dot is welded are determined using the weldable period for each dot. Here, as a first condition, the welding time for each dot is considered, and the time at which welding is performed is determined in such a manner that the welding time for each dot can be reliably satisfied regardless of the order of the start time of the weldable period for each dot. For example, assume a case in which there are two dots A and B whose welding times are both 1 second, the weldable period for the dot A is from the 1st second to the 4th second from the start of the action, and the weldable period for the dot B is from the 1.1st second to the 2.1st second from the start of the action. In this case, the dot A can be welded first, but if the dot A is welded from the 1st second to the 2nd second, the welding of the dot B cannot be performed. In this case, the dot B is welded from the 1.1st second to the 2.1st second, and the dot A is welded from the 2.1st second to the 3.1st second.

[0062] Next, in process 5, the operation speed is optimized in such a manner that all the dots can be welded and the cycle time is shortened. For example, it is possible to consider the following approach: the operation speed of the robot 110 is set to the same value for all the dot groups, the operation speed is lowered until all the dots can be welded, and then the operation speed is increased for each dot group. The above ends the determination process of the operation speed in step S25.

[0063] In the determination process of the operation path and the operation speed in step S11, the path determination section 162 can also determine the posture of the robot 110 (i.e., the posture of the scanner 90) as follows. Assume a scenario in which the robot 110 welds a certain dot while moving. During the period in which the robot 110 irradiates laser light for welding the dot, the dot needs to continuously be located within the irradiation range of the scanner 90. When the irradiation range of the scanner 90 is assumed to be rectangular, if the moving direction of the robot 110 is along one of the longitudinal side and the lateral side of the irradiation range, the distance that the robot 110 can move during the welding time of the dot becomes longer, and the operation speed of the robot 110 can be further increased. In addition, the cycle time can be shortened thereby. In this regard, reference is made to Figure 6A and Figure 6B for an explanation.

[0064] In Figure 6A and Figure 6B , the irradiation range (scanning range) of the scanner 90 mounted to the wrist of the robot 110 is denoted by reference numeral 90A. In addition, in Figure 6A and Figure 6B , an XY coordinate system fixed to the wrist of the robot 110 (i.e., fixed to the scanner 90) is shown. The irradiation range 90A is a rectangular region having a width WX in the X-axis direction and a width WY in the Y-axis direction. In Figure 6A , it is assumed that the scanner 90 is moved in a direction parallel to the X-axis (A direction in Figure 6A ) when laser light is irradiated to the dot 221. In this case, the moving direction A of the robot 110 is a direction along the side (X-axis direction) of the irradiation range 90A, and thus the robot 110 can move a distance LI during the welding time of the dot 221.

[0065] On the other hand, assume that the wrist of the robot 110 (i.e., the scanner 90) is moved in a direction parallel to the Y-axis (B direction in Figure 6BThe case of moving in the direction of arrow B in the figure in such a posture. In this case, the moving direction of the robot 110 does not follow the direction of the side of the irradiation area 90A. Therefore, during the welding time when the robot 110 welds the dot 221, the distance that the robot 110 can move is the distance L2. The distance L2 is shorter than the distance L1 (L2 < L1). From the above content, it can be understood that if the moving direction of the robot 110 follows a certain side (X-axis or Y-axis) of the irradiation range of the scanner 90, the distance that the robot 110 can move during the welding time of this dot becomes longer. That is to say, the action speed of the robot 110 can be increased.

[0066] Figure 7 An example showing the case of determining the posture of the robot 110 (scanner 90) when moving on the path R1 - R3 in such a way that the moving direction of the robot 110 follows a certain side (X-axis or Y-axis) of the irradiation range of the scanner 90. In Figure 7 this example, on the path R1, the posture of the wrist of the robot 110 is determined in such a way that the Y-axis of the irradiation range 90A is parallel to the path R1. On the path R2, the posture of the wrist of the robot 110 is determined in such a way that the X-axis of the irradiation range 90A is parallel to the path R2. On the path R3, the posture of the wrist of the robot 110 is determined in such a way that the Y-axis of the irradiation range 90A is parallel to the path R3.

[0067] In the case of determining the posture of the wrist (scanner 90) of the robot 110 as described above, a rotational movement of the scanner 90 around the vertical axis occurs. The rotation of the scanner 90 around the vertical axis may cause torsion of the optical fiber 81. In the step S12 of the action program determination process ( Figure 3 ), the torsion amount evaluation unit 164 evaluates the torsion amount of the optical fiber 81 through physical simulation. Refer to Figures 8-10 to explain the physical simulation of the torsion amount of the optical fiber 81 as a linear body.

[0068] Figure 8 is a perspective view showing an example of the linear body model 2 having a circular cross-section. As Figure 8 shown, the linear body model 2 is formed by a plurality of mass points 3 and a plurality of spring units 4 connecting between the mass points 3. The mass points 3 include a first mass point 31 and a second mass point 32 arranged on a plane 20 perpendicular to the long side direction of the linear body. The first mass point 31 is arranged at the radial center of the plane 20. The second mass points 32 are arranged at equal intervals in the circumferential direction around the first mass point 31, defining the outer peripheral surface of the linear body. The first mass point 31 and the second mass points 32 are arranged at equal intervals in the long side direction of the linear body. Each mass point 3 has mass information, three-dimensional position information (position data), and three-dimensional velocity information. The mass of each mass point 3 can be set to the value obtained by dividing the mass of the linear body by the number of mass points.

[0069] The spring unit 4 includes first springs 41 connecting the second particles 32 arranged on the circumference of the same plane 20, second springs 42 extending radially on the plane 20 from the first particle 31 and connecting the first particle 31 and the second particle 32, third springs 43 sequentially connecting the first particles 31 and the second particles 32 arranged in a row along the long side direction of the line body, and fourth springs 44 obliquely connecting the second particles 32 arranged in the long side direction. The first springs 41 and the second springs 42 represent the elasticity in the radial direction of the line body, and the third springs 43 and the fourth springs 44 represent the elasticity in the long side direction of the line body.

[0070] The torsion amount evaluation section 164 sets a plurality of points of interest 33 for grasping the torsion state of the line body on the line body model 2. In this case, the points of interest 33 are set on the line body model 2 in the following manner. Figure 8 More specifically, the points of interest 33 are set on the second particles 32 arranged in a row along the long side direction of the line body via the third spring unit 43 in a part of the circumferential direction of the line body model. The points of interest 33 can be arbitrarily set on the line body model 2 by the user through the operation section of the laser processing teaching device 60.

[0071] The torsion amount evaluation section 164 causes the robot model to act in accordance with a predetermined action program, and simulates the behavior of the line body accompanying the action of the robot. That is, as the robot model acts, the gravitational force, the damping force, and the elastic force from the spring unit 4 acting on each particle 3 of the line body model 2 are calculated every predetermined unit time, and the simulation (physical simulation) of changing the position of each particle 3 is executed every unit time.

[0072] In this case, the elastic force Fl of the spring unit 4 acting on the particle 3A when the particle 3A and the particle 3B are connected to each other via the spring unit 4 can be calculated by the following formula (I).

[0073] Fl = (unit vector from 3A to 3B) x spring constant x spring extension amount (I)

[0074] In the above formula (I), the extension amount (spring extension amount) of the spring unit 4 is set as a value obtained by subtracting the natural length of the spring unit 4 from the length of the spring unit 4 in a certain state. The natural length of the spring unit 4 corresponds to the distance between the particles 3A and 3B in the natural state in which the line body model 2 has no extension and no bending.

[0075] The damping force of the spring unit has a damping force F2 for suppressing the vibration of the spring and a damping force F3 for suppressing the translational motion of each particle 3, and can be calculated by the following formulas (II) and (III), respectively.

[0076] F2 = v x inner product of v x damping coefficient of vibration (II)

[0077] F3 = velocity of each mass x attenuation coefficient of translational motion (III)

[0078] In the above equation (II), v is a unit vector of (velocity of mass 3B - velocity of mass 3A). The attenuation forces F2, F3 act in such a way as to slow down the motion of the spring.

[0079] The gravitational force F4 acting on each mass 3 can be calculated by the following equation (IV).

[0080] F4 = unit vector of gravitational force direction x gravitational acceleration x mass of the mass (IV)

[0081] Further, when a mass 3 of the line body model 2 collides with some interfering surface, a repulsive force acts on the mass 3. In consideration of this, the repulsive force acting on the mass can also be calculated in addition to the elastic force, the gravitational force, and the attenuation force. In this case, the value of the component of the velocity of the mass at the time of collision in the normal direction of the collided surface becomes the value obtained by multiplying the velocity before the collision by a repulsive coefficient and inverting the sign. At this time, the repulsive force can be calculated by multiplying the acceleration obtained by dividing the change in velocity before and after the collision by the unit time by the mass of the mass.

[0082] The twist amount evaluation section 164 further calculates the resultant force of the forces Fl to F4 acting on each mass 3, and calculates the acceleration of the mass 3 by dividing the resultant force by the mass. In addition, the change in velocity of the mass 3 is calculated by the acceleration x unit time, and the velocity of the mass 3 is calculated by adding the change in velocity to the velocity of the mass 3. Furthermore, the displacement amount of the mass 3 is calculated by the velocity x unit time, and the position of the mass 3 is calculated by adding the displacement amount to the three-dimensional position data of the mass 3.

[0083] That is, the twist amount evaluation section 164 changes the position of the mass 3 at the line body mounting section (the connection section of the optical fiber 81 connected to the scanner 90) in cooperation with the motion of the robot every unit time, calculates the forces Fl to F4 acting on each mass 3 as described above, and calculates the resultant forces thereof, and simulates the behavior of the line body by updating the velocity and the position of each mass 3. Thereby, the time-series position data of each mass 3 can be obtained. In addition, the attention point 33 is a part of the mass 3, and thus the position data of the attention point 33 can also be obtained.

[0084] Figure 9 is a drawing illustrating one example of a line body image 51 obtained by visualizing the state of the line body according to the simulation result and an attention point image 52 in the case of visualizing the attention point. In Figure 9In the middle, the line body image 51 is indicated by a solid line, and the attention point image 52 is indicated by a black circle. The attention points 33 are set in a line in the long side direction at the same phase in the circumferential direction of the line body, so when the line body is twisted, as shown in Figure 9 the attention point image 52 becomes a state of being twisted on the line body image 51.

[0085] The twist amount evaluation section 164 has a function of calculating a twist amount in order to further quantitatively indicate the twisted state of the line body. Figure 10 is a diagram that explains the process of calculating the twist amount. In Figure 10 , 20n, 20n+1 are planes of the line body model 2 in which the particles 3 are set, which are adjacent to each other, 31n, 31n+1 are particles that are located at the central portions of the planes 20n, 20n+1, respectively, and 32n, 32n+1 are particles that are located at the same positions (same phase) in the circumferential direction on the circumferences of the planes 20n, 20n+1, respectively. The particles 32n, 32n+1 are, for example, the attention points 33.

[0086] The twist amount of the line body between the planes 20n, 20n+1 can be defined by the angle formed by the faces formed by the particles 31n, 32n, 31n+1 and the faces formed by the particles 31n+1, 32n+1, 31n. As an example, toward the front end portion (scanner side) in the length direction of the line body, the twist in the clockwise direction is defined as positive and the twist in the counterclockwise direction is defined as negative. Under such a definition, the twist amount evaluation section 164 calculates the twist amount of the entire optical fiber 81 that is connected at one end to the central portion of the upper surface 90a of the scanner 90. Further, in the case where the optical fiber 81 is fixed to the arm of the robot 110 at an intermediate position, the twist amount can also be calculated between the connection end of the optical fiber 81 that is connected to the scanner 90 and the mounting position that is mounted to the robot 110.

[0087] The twist amount evaluation section 164 evaluates the twist amount of the optical fiber 81 in the case where the robot 110 moves on each path R1-R3 (i.e., the entire action path). For example, it is set to calculate the twist amount of the optical fiber 81 in the case where the robot 110 acts on the path R1, the path R2, and the path R3, respectively, and it is set to the twist amounts T1, T2, T3. The twist amount evaluation section 164 compares the twist amounts T1, T2, T3 with a prescribed allowable range. In the case where there is a twist amount that exceeds the prescribed allowable range, the twist amount evaluation section 164 sets the action of the robot 110 in the case where the twist amount exceeds the allowable value as an object of posture change (step S12).

[0088] Next, in step S13, the robot posture changing section 165 changes the posture of the robot 110 whose twist amount exceeds the allowable range. For example, in the case where the direction of the twist is the positive direction, the change of the posture can be performed by rotating the scanner 90 around an axis parallel to the axis direction of the connection end portion 81a to which the optical fiber 81 is connected to the scanner 90 in such a manner that the optical fiber 81 is twisted in the negative direction. The rotation around the axis parallel to the axis direction of the connection end portion 81a means, for example, rotation around the axis of the connection end portion 81a or rotation around an axis in the vertical direction passing through the center of the upper surface 90a of the scanner 90.

[0089] As an example, in the case where the state of the robot 110 is observed from above as shown in FIG. 8, the twist amount in the path Rl exceeds the allowable range in the clockwise direction and the twist amount in the path R3 exceeds the allowable range in the counterclockwise direction. In this case, with respect to the movement of the path Rl, the robot posture changing section 165 changes the posture of the robot 110 in such a manner that the scanner 90 is rotated counterclockwise (in the direction of the arrow C2 in FIG. 8). With respect to the movement of the path R3, the robot posture changing section 165 changes the posture of the robot 110 in such a manner that the scanner 90 is rotated clockwise (in the direction of the arrow C1 in FIG. 8). The change of the posture in step S13 can be performed in such a manner that the twist amount of the path Rl is changed to be within the allowable range and the twist amount of the path R3 is changed to be within the allowable range. Figure 11 Figure 11 As an example, in the case where the state of the robot 110 is observed from above as shown in FIG. 8, the twist amount in the path Rl exceeds the allowable range in the clockwise direction and the twist amount in the path R3 exceeds the allowable range in the counterclockwise direction. In this case, with respect to the movement of the path Rl, the robot posture changing section 165 changes the posture of the robot 110 in such a manner that the scanner 90 is rotated counterclockwise (in the direction of the arrow C2 in FIG. 8). With respect to the movement of the path R3, the robot posture changing section 165 changes the posture of the robot 110 in such a manner that the scanner 90 is rotated clockwise (in the direction of the arrow C1 in FIG. 8). The change of the posture in step S13 can be performed in such a manner that the twist amount of the path Rl is changed to be within the allowable range and the twist amount of the path R3 is changed to be within the allowable range. Figure 11

[0090] The result of the correction of the posture in step S13 can cause a dot that deviates from the irradiation range during the welding time for which the dot is specified. In step S14, adjustment is performed with respect to such a dot so that the dot does not deviate from the irradiation range during the welding (laser irradiation). Specifically, the dot is caused not to deviate from the irradiation range during the welding by reducing the movement speed of the robot 110 or adjusting the timing of the welding of the dot. As an example, the adjustment of the welding timing can be performed by recalculating the weldable period of each dot and setting the welding period of the dot again in such a manner that the welding period does not interfere with the dots before and after the dot. The adjustment process is repeated until all the dots do not deviate from the irradiation range during the welding (steps S14 and S15).

[0091] ​​Then, the series of processes of steps S12 to S15 (an action of reevaluating the twist amount after changing the posture of the robot) are repeated until the twist amount is within the allowable range in the entire action path of the robot 110 (step S16).

[0092] The action program creation section 166 creates an action program of the robot 110 and the scanner 90 using various information including the action path generated as above, the action speed, and the welding period.

[0093] Through the above processing, teaching (i.e., generating an action program for performing a prescribed welding operation) in the laser processing system 100 can be performed in a manner that the twist amount of the optical fiber 81 is within the allowable range. Thereby, it is possible to prevent a situation where the optical fiber 81 is broken in the welding operation performed by the robot 110.

[0094] The above describes the present application using typical embodiments, but as long as those skilled in the art, it should be understood that each of the above embodiments can be changed, and various other changes, omissions, additions can be made without departing from the scope of the present application.

[0095] In the above embodiments, the posture of the robot is corrected in the case where the twist amount exceeds the allowable range, but instead of this, or simultaneously with this, the optical fiber 81 can be installed to the scanner 90 in a manner that it is twisted in a direction to eliminate the twist amount. For example, if the twist amount is 30 degrees in the positive direction in the behavior simulation, the optical fiber 81 can be installed to the scanner 90 in a manner that it is twisted by 15 degrees in the negative direction, so that the twist amount is ±15 degrees and within the allowable range (±15 degrees). Further, as a method of calculating the twist amount of the wire body through simulation, a method known in the art other than the method shown in the above embodiments can be applied.

[0096] The above embodiments are not limited to optical fibers, and can be applied to eliminating the twist of various cables attached to a robot.

[0097] A program that performs various processes (teaching method) such as the action program creation process, the generation of the action path, the determination of the action speed, and the action speed determination process described in the above embodiments can be recorded in various recording media (e.g., ROM, EEPROM, flash memory, magnetic recording media, CD-ROM, DVD-ROM, and the like) that can be read by a computer.

[0098] Explanation of Reference Numerals

[0099] 2: line model; 3: particle; 4: spring unit; 20: plane; 51: line image; 52: point-of-interest image; 60: laser processing teaching device; 70: robot control device; 71: motion control section; 80: laser oscillator; 81: optical fiber; 81a: connection end portion; 90: scanner; 90A: irradiation range; 91: control section; 100: laser processing system; 110: robot; 161: data input section; 162: path decision section; 163: simulation execution section; 164: twist amount evaluation section 164; 165: robot posture change section; 166: motion program creation section; R1-R3: path.

Claims

1. A teaching pendant for teaching the motion of a robot in a laser processing system comprising a laser processing head connected to an optical fiber and a robot for moving the laser processing head, the teaching pendant comprising: The path determination unit determines the robot's motion path based on the positions of multiple processing points set on the object; The simulation execution unit performs the robot's motion simulation according to the determined motion path; The torsion evaluation unit calculates the torsion of the optical fiber by simulating the behavior of the optical fiber according to the robot's motion simulation, and evaluates the torsion by comparing the torsion with a specified allowable range. as well as The robot posture modification unit changes the robot's posture in a manner that reduces the amount of twisting when the robot's movement exceeds the predetermined allowable range. The laser processing head is a structure that emits laser light in a scanning manner, and the scanning range of the laser light emitted from the laser processing head is rectangular. The path determination unit determines the robot's posture when it moves along the motion path in a manner that makes the robot's motion direction and posture change with the robot's posture.

2. The teaching device according to claim 1, wherein, The torsion evaluation unit and the robot posture change unit repeatedly perform the action of evaluating the torsion again after changing the robot's posture until the torsion of the optical fiber is within the specified allowable range throughout the entire motion path.

3. The teaching device according to claim 1 or 2, wherein, The path determination unit, in response to the robot's movement that results in the processing point being out of the scanning range of the laser emitted by the laser processing head during welding due to the robot's posture being changed by the robot posture change unit, reduces the robot's movement speed or adjusts the welding timing of the processing point, thereby bringing the processing point within the scanning range during welding.

4. The teaching device according to claim 1 or 2, wherein, The robot posture changing unit changes the robot's posture by rotating the laser processing head about an axis parallel to the axis of the connection end of the optical fiber connected to the laser processing head.

5. A teaching method for teaching the motion of a robot in a laser processing system comprising a laser processing head connected to an optical fiber and a robot for moving the laser processing head, the teaching method comprising: The robot's motion path is determined based on the positions of multiple processing points set on the object; The robot performs motion simulation according to the determined motion path; The amount of twist of the optical fiber is determined by simulating the behavior of the optical fiber according to the robot's motion based on the motion simulation, and the amount of twist is evaluated by comparing the amount of twist with a specified allowable range. as well as For robot movements where the amount of twist exceeds the specified allowable range, the robot's posture is changed in a manner that reduces the amount of twist. The laser processing head is a structure that emits laser light in a scanning manner, and the scanning range of the laser light emitted from the laser processing head is rectangular. The robot's posture when moving along the motion path is determined in a manner parallel to one side of the scanning range, such that the robot's direction of motion and posture along the motion path change with the robot's posture.

6. The teaching method according to claim 5, wherein, The action of evaluating the amount of torsion again after changing the robot's posture is repeated until the amount of torsion of the optical fiber is within the specified allowable range throughout the entire motion path.

7. The teaching method according to claim 5 or 6, wherein, In response to the robot's actions that result in the processing point being out of the scanning range of the laser emitted by the laser processing head during welding, as a result of changing the robot's posture, the robot's movement speed is reduced, or the welding timing of the processing point is adjusted, thereby bringing the processing point within the scanning range during welding.

8. The teaching method according to claim 5 or 6, wherein, The robot's posture is changed by rotating the laser processing head about an axis parallel to the axis of the connection end of the optical fiber that is connected to the laser processing head.

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