JP2009262306A - Method of teaching robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically prepare a teaching point for proper synchronization of a positioner when an operation such as a welding for synchronizing a robot with the positioner is taught. <P>SOLUTION: In this method of teaching a robot, the length of a working path for a workpiece 100 which is required for the operation of the positioner is obtained from an operation speed to the workpiece 100 in a district in which the operation of the positioner 2 for obtaining in advance the operation time of the positioner 2 from the operation start position to the operation end position is included (S2-5). The interlocking start position and the interlocking end position are so set that the length of the working path for the workpiece 100 from the operation start position to the operation end position of the positioner 2 is equal to or more than that of the working path required for the operation of the positioner (S2-6). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for teaching the operation of an industrial robot. In particular, the present invention relates to a teaching method for a robot such as a welding robot having a positioner for positioning a workpiece.

  In recent years, various operations such as welding, painting, deburring, and cutting have been increasingly performed by industrial robots. In addition, from the viewpoint of work quality and work efficiency, work for operating a robot while operating a positioner (work positioning device) for gripping a work is increasing.

  In the case of teaching a robot in which a workpiece is installed on a positioner, welding may be continuously performed on a welding line with a variable curvature or a welding line having a broken line in order to avoid welding defects. At this time, from the viewpoint of the operation range of the robot and the welding quality, it is common to perform welding while operating the positioner before and after the portion where the curvature changes or the bending portion.

  At this time, a sharp change of the positioner occurs in a broken line part or a part with a large curvature. For example, when the teaching points 1 to 4 are set so as to always keep the welding lines W1 and W2 bent at right angles as shown in “state 1” to “state 3” in FIG. 10, as shown in “state 3”. A sudden change of the positioner occurs at the bent portion (between teaching points 2 and 3). Actually, the positioner stops or operates at the speed limit by a protection mechanism such as an operation speed limit. For this reason, the position where the operation of the positioner starts and the position where the operation ends are manually set as teaching points before and after the curvature portion and the bent portion so as not to exceed the speed limit. “State 1” to “State 5” in FIG. 11 show an example of setting such a new teaching point. In this example, as in the case of FIG. 10, the teaching points are set so that the welding lines W1, W2 are always kept horizontal. The teaching points 1 and 5 in FIG. 11 correspond to the teaching points 1 and 4 in FIG. 10, respectively, and the teaching point 3 in FIG. 11 corresponds to the teaching points 2 and 3 in FIG. The teaching points 2 and 4 in FIG. 11 are teaching points set so as to enable the positioner operation. Specifically, in the example of FIG. 11, the positioner starts operation at the teaching point 2 in synchronization with the robot, and this synchronization operation ends at the teaching point 4 (the operation start position of the positioner ends at the teaching point 2). The position is the teaching point 4.) This type of technology is disclosed in Patent Document 1, for example.

JP-A-2-307777

  In the method in which the teaching operator sets the operation start position and the operation end position of the positioner, it is necessary to confirm whether or not a teaching point that does not exceed the speed limit is actually realized by the synchronous operation of the positioner and the robot. Since the section for performing the synchronous operation deviates from the original high-quality welding conditions, it is desirable to set the section as short as possible. However, if this section is too short, an operation exceeding the speed limit occurs. If the speed limit is exceeded, even if the robot or positioner does not stop, the welding speed under the set welding conditions cannot be realized, resulting in a deterioration in welding quality. Therefore, while repeating trial and error, the teaching point of the section where positioner synchronization is performed is set so that this section is as short as possible and the speed does not exceed the speed limit. This required a lot of labor and time.

  The present invention has been made in view of this point, and provides a method for automatically creating an appropriate teaching point for positioner synchronization in teaching work such as welding for synchronizing a robot and a positioner. In addition, it is possible to reduce the teaching work time by automatically inspecting whether or not the appropriate teaching points for positioner synchronization have been set for the already created teaching data and displaying the inspection result to the operator. It is intended to improve work quality such as welding quality.

  In order to achieve the above object, the first aspect of the present invention sets the position / posture to be taken by the positioner before and after the curvature part of the work trajectory and the bending point when teaching the robot. The operation time required for the moving operation is obtained from the maximum speed or rated speed of the drive unit and the acceleration / deceleration pattern. By calculating the length of the work trajectory and making it an interlocking section that synchronizes with the positioner, the teaching point is automatically set to be the calculated trajectory length, reducing labor and time required for teaching the robot with the positioner Is realized.

  In other words, according to a first aspect of the present invention, in a teaching method for a robot that performs work while operating a positioner, an operation time from the operation start position of the positioner to an operation end position is obtained in advance, and a section including the operation of the positioner The length of the work trajectory for the work required for the positioner operation is obtained from the work speed for the work at the position, and the length of the work trajectory for the work from the operation start position to the operation end position of the positioner is the work required for the positioner operation. Provided is a robot teaching method for setting an interlock start position and an interlock end position that are longer than the length of a trajectory.

  The section from the start to the end of the operation of the positioner is divided, and the method of the first aspect can be applied to each section. That is, in the first aspect, when a finer work speed is set according to each posture change of the positioner, the interlocking section is divided according to the range of the posture of each positioner, and the same operation is used to teach By automatically setting the points, it is possible to reduce labor and time required for teaching a robot having a positioner.

  The second aspect of the present invention derives the shortest operating time of the positioner in the section where the positioner changes with respect to the teaching data created in advance, and requires a positioner that is multiplied by this time to work speed. Deriving the length of the shortest work trajectory, alerting the operator if the target length is longer than the target trajectory length, and displaying the trajectory length of that section and the required trajectory length as necessary As a result, the work efficiency can be improved and teaching data for realizing higher quality welding can be created in a short time.

  That is, according to the second aspect of the present invention, the synchronous work section between the positioner and the robot is extracted based on the created teaching data, the operation time from the operation start position to the operation end position of the positioner, and the synchronous work section The length of the work trajectory required for the positioner operation is obtained from the work speed of the robot with respect to the work, and the teaching position is corrected when the work trajectory for the work in the synchronized work section is shorter than the length of the work trajectory required for the positioner operation. Provided is a robot teaching method for outputting a warning for prompting.

  According to the first aspect of the present invention, it is possible to automatically create teaching data that does not exceed the speed limit of the positioner and enables the set work speed, thereby improving work efficiency and welding quality. .

  According to the second aspect of the present invention, the created teaching program is checked, and the position of the teaching point to be corrected is numerically displayed as necessary. I can plan.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  In this embodiment, an example of a robot system as shown in FIG. 1 is shown. The robot system includes a welding robot (hereinafter simply referred to as “robot”) 1 and a positioner 2 that holds a workpiece 100 to be welded at a predetermined position, and a controller 3 that controls the robot 1 and the positioner 2. The robot 1 holds the welding torch 4 as a processing tool. The robot 1 is a general articulated robot as an industrial robot, but may be another type of robot. The positioner 2 includes a mounting surface 2a of the workpiece 100, and rotates the mounting surface 2a around the rotation axes θ1 and θ2 illustrated in FIG. The rotation axis θ1 is a rotation axis extending vertically from the center of the mounting surface 2a, and the rotation axis θ2 is a rotation axis in the horizontal direction. The posture of the positioner 2 is represented by coordinates around each rotation axis, that is, (θ1, θ2).

  The robot 1 and the positioner 2 are controlled by a control device 3 equipped with a computer, and the control device 3 controls the robot in accordance with a program taught in advance. The teaching program is created in advance using the teaching pendant 5 attached to the control device or using the offline teaching system 6 using a personal computer. The program created by the offline teaching system 6 may be transferred to the control device 3 via a magnetic disk (floppy (registered trademark) disk) or a memory device, or transferred to the control device 3 by data communication. .

  The offline teaching system 6 includes a graphic display 7 as a display device, and includes a keyboard and a mouse as input devices. Further, a magnetic storage device and a communication device are provided as the data input device 9 for capturing CAD information of the workpiece 100. As described above, the teaching program is transferred to the robot controller using these. Further, the offline teaching system 6 includes a display control unit 11 that controls the graphic display 7, an input control unit 12 that controls input from the input device 8 and the data input device 9, and a memory that stores data, various conditions, programs, and the like. An arithmetic unit 14 that performs various arithmetic processes in cooperation with the unit 13 is provided.

  The teaching program creation method (robot teaching method) according to the present embodiment includes the following six processes which are operations on the offline teaching system 6 or processes executed by the offline teaching system itself. FIG. 2 shows a flowchart (steps S2-1 to S2-7) of the present embodiment. From the teaching operator's standpoint, a teaching program is created by inputting conditions including values used using an input device (mouse or keyboard) 8 in accordance with the display on the graphic display 7 of the offline teaching system 6.

Process 1: The position of the weld line is designated (step S2-1).
Process 2: The position of the positioner 2 with respect to each weld line is set (step S2-2).
Process 3: The welding conditions for the weld line and the attitude of the welding torch 4 are set (steps S2-3 and S2-4).
Process 4: The trajectory length required to synchronize the positioner 2 and the robot 1 is calculated (S2-5).
Process 5: According to the trajectory length calculated in process 4, the position of the synchronization start and synchronization end of the positioner 2 is set (step S2-6).
Process 6: The teaching point of the welding posture and the positioner synchronization section is sequentially created under the set conditions in Shiga.

  Various operations in the following description of each process are basically internal processes executed by the off-line teaching system 6 according to a program unless otherwise specified.

  In step 1, the teaching operator designates the welding position based on the information of the workpiece 100 read into the offline teaching system 6. In the present embodiment, for the sake of simplicity, it is assumed that two welding lines W1 and W2 continuous to the workpiece 100 having the dimensions shown in FIGS. 3A and 3B are set. In this embodiment, a virtual orthogonal coordinate system (flange coordinate system Σf) in which the origin is fixed at the center of the workpiece mounting surface 2a of the positioner 2 shown in FIGS. 3A and 3B is used. With this flange coordinate system Σf as a reference, the first welding lines W1 (200, 200, 20) to (200, -200, 20) (mm) and the second welding lines W2 (200, -200, 20). ) To (−200, −200, 20) (mm).

  In the process 2, the teaching operator sets the position of the positioner 2 when performing work on the welding lines W1 and W2. Usually, it sets so that the groove | channel of a welding line may face upwards and a welding line may become horizontal. In the positioner 2 and the workpiece 100 of the present embodiment, the positioner posture P1 (45 °, 0 °) with respect to the first welding line W1, and P2 (45 °, with respect to the second welding line W2). When set to 90 °, the desired posture is obtained. FIG. 4 shows the appearance of the positioner 2 in the positioner posture P1 (45 °, 0 °).

  In process 3, the teaching operator sets the welding conditions and welding postures for the welding lines W1 and W2. As the welding conditions, the position of the back step at the start of welding, the welding conditions and the torch attitude, the welding conditions and the torch attitude in the main welding, and the welding conditions and the torch attitude at the end of welding are specified. In addition, the welding conditions at the broken line portion and the curved portion are specified. Here, the welding conditions include welding current, voltage, welding speed, and weaving operation. The welding conditions may be specified in the form of a command macro that collectively sets these conditions. 5A to 5C respectively show an example of a welding condition setting screen at the welding start end, a welding condition setting screen at the broken line portion, and a welding condition setting screen at the end portion displayed on the graphic display 7.

  In the process 4, the trajectory length necessary for the operation of the positioner 2 is calculated in the broken line section where the synchronization between the positioner 2 and the robot 1 occurs. “Process 4” is executed by the off-line teaching system 6 itself.

  Assume that the angle change of the i-th positioner shaft is Δθi (deg), and the maximum angular velocity (or rated angular velocity) of the positioner shaft is βi (deg). When it is assumed that time is not required for acceleration / deceleration, the time ti (sec) required for the operation of the angle change Δθi is expressed by the following equation (1).

  Actually, since the angular velocity of the positioner 2 operates close to an acceleration / deceleration pattern as shown in FIGS. 6 and 7, the time required for the operation is a slightly more complicated calculation. Assuming that the acceleration / deceleration time is ta (sec) until reaching the angular velocity βi, in the case of βi × ta ≦ Δθi, that is, until the angular velocity of the i-th positioner shaft reaches 0 to βi, the angle change of the positioner shaft is less than Δθi. In some cases, the time ti required for the operation of the angle change Δθi is expressed by the following equation (2) (FIG. 6).

  On the other hand, when βi × ta> Δθi, that is, when the angular change of the positioner axis reaches Δθi until the angular velocity of the i-th positioner axis reaches βi, the time ti required for the operation of the angular change Δθi Is represented by the following equation (3) (FIG. 7).

  This time ti is calculated for all the positioner axes. As shown in the following formula (4), the maximum value of the time ti is the time t required for the posture change of the positioner 2.

Next, the weld line length L _weld necessary for the posture change of the positioner 2 is calculated. If the working speed set in the polygonal line section, here the welding speed, is V _weld (mm / sec), the weld line length L _weld (mm) required for the position change of the positioner 2 is It is represented by (5).

In the present embodiment, the change from the positioner posture P1 to P2 is (0, 90), and the second axis (θ2) changes by 90 °. When the rated speed of the second axis is 10 ° / sec, the time required for acceleration / deceleration is 0.5 sec, and the welding speed is 5 mm / sec (= 30 cm / min), the weld line length L _weld required for the position change of the positioner (Mm) is 47.5 mm as shown below from equations (2) and (5).

In “Process 5”, an interlocking section of this trajectory length is required on the weld lines W1 and W2 with respect to the workpiece 100 before and after the broken line portion with respect to L _weld derived in “Process 4”. As shown in the explanation of “Process 4”, the acceleration / deceleration pattern of the positioner 2 is approximate. Therefore, when this value is calculated at the maximum angular velocity, the effects of control and dynamic influences are taken into account. Some margin is required. Even when the rated speed is used, it is preferable to provide a margin for the system. Let L be the trajectory length in consideration of this margin amount ΔL.

  In the broken line section, it is necessary to insert teaching points for starting and ending the interlocking of the positioner 2 and the robot 1 at positions half the trajectory length L before and after the vertex of the polygonal line. Also, in a section with curvature, similarly, when the length of the curvature portion is smaller than the locus length L, the teaching points for starting and ending interlocking of the positioner 2 and the robot 1 are inserted before and after the curvature portion, It is necessary to distribute the angles so that the operation of the positioner is smooth at each curvature part. In this embodiment, the margin length is set to a distance corresponding to 0.5 seconds, and the locus length L = 50 mm including 2.5 mm is added, and the positioner 2 and the robot 1 are linked to the position 25 mm before the broken line portion and the position of the broken line portion 25 mm. Set the start and end of interlocking position. The setting of the interlocking position of the interlocking start and the interlocking end may be set by the teaching operator based on the display on the graphic display 7, or may be executed by the offline teaching system 6. Since the workpiece 100 is held by the positioner 2, the locus on the workpiece 100 becomes the locus length in the flange coordinate system Σf. Since it is necessary to protect the work speed with respect to the workpiece 100, the time t required for the posture change of the positioner 2 may be converted into the trajectory length L on the workpiece 100, and complicated coordinate conversion is unnecessary.

  In “Process 6”, teaching points (approach point, arc start point, synchronization interval, arc end point, retraction point) that are the operations of the robot 1 and the positioner 2 from the specified positioner 2 position and welding torch 4 position. Are sequentially set by the teaching operator.

  The teaching data set in this way realizes the set work speed in the positioner synchronization section, for example, the welding speed that greatly affects the quality of the work, and minimizes the synchronized section as much as possible. Thus, it is possible to easily perform the maximization of the welding section where high quality welding is possible.

  The operation taught to the robot 1 and the positioner 2 by the method of this embodiment is conceptually shown from “state 1” to “state 5” in FIG. The teaching point 1 corresponds to the welding start end, the teaching point 5 corresponds to the welding end end, the teaching point 3 corresponds to the apex of the broken line (the connection position of the welding lines W1, W2. The teaching points 2 and 4 correspond to the positioner 2 and the robot 1. The teaching points 2 and 4 are such that the length of the work trajectory with respect to the workpiece 100 from the operation start position to the operation end position of the positioner 2 is the work required for the operation of the positioner 2. It is set to be longer than the length of the trajectory.

  As a modified example of the second embodiment, the operation from the start of the positioner to the end of the operation may be divided into a plurality of sections, and steps 1 to 6 may be executed in each section.

(Second Embodiment)
The second embodiment is a method for checking a teaching program already created using the teaching pendant 5 in the robot system or a teaching program created by the offline teaching system 6. In the following description, it is assumed that the off-line teaching system performs, but it can also be executed by the control device 3 of the robot system or another computer. The method of the present embodiment generally includes the following four processes. FIG. 9 shows a flowchart (steps S9-1 to S9-8) of the present embodiment.

Process 1: A set (teaching point sequence) of teaching point (i) to teaching point (i + 1) having a positioner change is extracted from the teaching program (step S9-1).
Process 2: The trajectory length L necessary for the positioner operation is calculated (step S9-2).
Process 3: The work length Li on the positioner 2 (on the flange coordinate system Σf) from the teaching point (i) to the teaching point (i + 1) is calculated (step S9-3).
Process 4: The trajectory length L of Process 2 is compared with the work length Li of Process 3, and the result is displayed. At this time, if Li <L, a warning is displayed on the graphic display 7 (steps S9-4 to S9-8).

  In step 1, the set teaching program is searched in order, and teaching point sequences (i) to (i + 1) that change the posture of the positioner 2 are extracted.

  In process 2, the synchronization time required for the positioner posture change is calculated from the change amount ΔP of the positioner 2. This calculation is the same as that of the process 4 of 1st Embodiment, and is calculated by above-mentioned Formula (2)-(4).

Further, assuming that the welding speed, which is the work speed set in this section, is V _weld with respect to the calculated synchronization time required for the positioner operation, the trajectory length L required for positioner synchronization is calculated according to the above (5). calculate.

  In step 3, the work length Li on the workpiece 100 at the set teaching point is derived. The working length on the workpiece 100 is a locus length in the flange coordinate system Σf. The position coordinates of the robot tip point (tip point of the welding torch 4 in this embodiment) with respect to the positioner 2 at the teaching point i and the teaching point i + 1 are respectively derived, and the working distance is defined as Li.

  In step 4, the trajectory L and the work length Li are compared. If Li <L, the work length according to the current teaching is the locus length L required for the positioner 2 to operate in synchronization with the robot 1 in the section of the teaching points (i) to (ii). L is insufficient. That is, if Li <L, the teaching points (i) and (ii) need to be corrected in order to ensure the synchronous operation of the positioner 2. Therefore, if Li <L, ΔL (= L−Li) is calculated, and ΔL is stored as length information that is not synchronized. The above processing is executed for all the teaching points (i) to (ii) where the posture of the positioner 2 is changed (steps S9-6 and S9-8 in FIG. 9). After that, all the teaching points (i) to (ii) satisfying Li <L are displayed on the graphic display 7 as warnings including their short lengths ΔL. The display mode of the warning is not particularly limited.

  In this way, the legitimacy of the teaching program once created is evaluated, and before the operation with the actual machine, the portion where the desired operation cannot be realized is extracted, and the teaching point to be corrected is quantitatively analyzed including the correction amount. Therefore, the work efficiency is greatly shortened and a teaching program with high welding quality can be easily created.

  The present invention is not limited to the embodiments, and various modifications are possible as listed below.

  Although an embodiment using an offline teaching system for a robot has been shown, it is also possible to implement this function by installing this function in the teaching function of a single robot.

  In the present embodiment, the teaching point creation method for positioner synchronization of a welding robot by an offline teaching system using a personal computer has been described. However, the present invention is incorporated in a robot control device, executed on a real machine, and displayed as a result. It is also possible to realize with.

  Further, not only a welding robot but also a robot (for example, a sealing robot or a painting robot) that performs a synchronization operation with a positioner can be applied by replacing the welding speed with a work speed or the like.

The typical perspective view showing an example of the robot system which performs the creation method of the teaching program which is a 1st embodiment of the present invention. The flowchart which shows the preparation method of the teaching program which is 1st Embodiment of this invention. The top view of a workpiece | work. Side view of the workpiece. The typical perspective view which shows an example of the attitude | position of a positioner. The schematic diagram which shows the welding condition setting screen of a welding start point. The schematic diagram which shows the welding condition setting screen of a broken line part. The schematic diagram which shows the welding condition setting screen of a termination | terminus part. The diagram which shows an example of the relationship between the acceleration / deceleration characteristic of a positioner axis | shaft, and an angle change. The diagram which shows the other example of the relationship between the acceleration / deceleration characteristic of a positioner axis | shaft, and an angle change. The conceptual diagram which shows an example of operation | movement of the robot system by the teaching program created with the method of 1st Embodiment. The flowchart which shows the preparation method of the teaching program which is 2nd Embodiment of this invention. The conceptual diagram for demonstrating an example of operation | movement of the positioner in case a welding line is a polygonal line shape. The conceptual diagram for demonstrating the setting of the teaching point before and behind a bending part in case a welding line is a broken line shape.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Welding robot 2 Positioner 2a Mounting surface 3 Control device 4 Welding torch 5 Teaching pendant 6 Offline teaching system 7 Graphic display 8 Input device 9 Data input device 11 Display control unit 12 Input control unit 13 Storage unit 14 Calculation unit 100 Workpiece

Claims (3)

In the teaching method of the robot that works while operating the positioner,
The operation time from the operation start position of the positioner to the operation end position is obtained in advance,
Finding the length of the work trajectory for the work required for the positioner operation from the work speed for the work in the section including the operation of the positioner,
Setting the interlock start position and the interlock end position such that the length of the work trajectory for the workpiece from the operation start position of the positioner to the operation end position is equal to or greater than the length of the work trajectory required for the positioner operation; Robot teaching method.   A robot teaching method, wherein a positioner operation start to an operation end are divided into a plurality of sections, and the method of claim 1 is applied to each section. Based on the created teaching data, extract the synchronous work section of the positioner and robot,
Obtaining the length of the work trajectory required for the positioner operation from the operation time from the operation start position of the positioner to the operation end position and the work speed of the robot with respect to the workpiece in the synchronous work section,
A robot teaching method for outputting a warning prompting correction of a teaching position when a work locus for the workpiece in the synchronous work section is shorter than a length of a work locus required for the positioner operation.

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