JP3902310B2 - Posture generation method for industrial robots - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a posture generation method for an industrial robot when a tool posture attached to the industrial robot has one redundancy degree of freedom.
[0002]
[Prior art]
In teaching work in a normal teaching playback type industrial robot, a teaching tool (usually, so that the position at the feature point of the work target is reached and the attitude at that position becomes the desired work position. , Which is called a programming pendant, teaching pendant or teaching pendant), sends a command to the controller body from the teaching tool to actually operate the robot and memorize its position and orientation. The controller main body stores the position and orientation in the storage unit. By repeating this, an operation program is created. Also, in order to make the appropriate tool posture section for the robot work target as long as possible before and after the point where the movement direction changes suddenly or the point where the appropriate tool posture changes for work, it is usually taught Dots have been added.
[0003]
For example, when the work target in arc welding is as shown in FIG. 2, when the welding is performed on a straight line connecting points P0, P1, P2, and P3, the characteristic points are points P0, P1, P2, and P3. . In the conventional teaching method, first, the robot is operated up to P0 using a teaching tool, and the posture determined by the material, welding conditions, etc. (target angle: angle formed between the welding torch and the work surface including the traveling direction (FIG. 3), Proceeding angle: The posture of the robot is changed using the teaching tool so as to take an angle formed by the welding torch and the traveling direction vector (the posture determined by FIG. 3). When the position and orientation are desirable, they are stored in the controller. Next, although P1 is taught, since the weld line changes suddenly at P1, the desired posture is different before and after P1. Therefore, normally, teaching points are created at an appropriate distance before and after the point P1. This point is represented as Ppre 1 and Ppost1 in FIG. By doing so, a sudden posture change at P1 was avoided. Ppre 2 and Ppost2 were created for P2 for the same reason. In P3, the position and orientation are stored as in the case of P0. In this way, the operation program is created as a storage of the positions and orientations at P0, Ppre1, P1, Ppost1, Ppre1, P2, Ppost2, and P3. However, in such a robot teaching method, it is necessary to teach the motion posture in addition to the motion position, and it is sometimes necessary to create teaching points before and after the feature point of the work target. However, the teaching of the robot is time-consuming. In addition, these operations require highly skilled techniques and time for moving the robot, and there are not many simple and objective methods for setting the posture. As a technique for solving these problems, there is a technique disclosed in JP-A-8-123536.
[0004]
[Problems to be solved by the invention]
However, in the method disclosed in Japanese Patent Laid-Open No. 8-123536, when determining the tool posture of the start point, end point, connection point, and auxiliary point, the spin obtained from the set target angle and advance angle, and the tool posture at the time of teaching. The tool posture is uniquely determined by the angle, and when determining this tool posture, whether or not the robot can actually take the posture has not been studied, and the robot posture may not be taken. there were. The reasons why the robot cannot take the posture include mechanical limitations, interference between the torch and the robot arm, and interference between the welding target member and the torch. Further, in the method disclosed in the publication, only one reference plane β can be set in an editing target section including a plurality of routes, and cannot be set for each section, so that auxiliary points are not added. there were. Further, in the above publication, “when considering a plane γ on which a straight line representing the direction of the torch 1 (the Z-axis direction of the tool coordinate system) rides with respect to this reference plane β, the plane γ forms with respect to the reference plane β The target angle is a rotation angle around a line formed by the intersection of the γ and β planes. When the tool posture is actually rotated by the target angle, The path axis is the center of rotation. There is a problem that the target angle cannot be set as the user thinks because the definition of the target angle is different from the target direction at the time of rotation. As described above, in the conventional method, since an operation program that can be operated practically cannot be created, it is necessary to modify the operation program, and the initial purpose of reducing the burden on the teacher cannot be sufficiently achieved. Therefore, the present invention creates an operational program that can be operated by teaching only the feature points of the work target, and generates an objective posture, thereby reducing the work load on the teacher and reducing variations between teachers. It is an object of the present invention to provide an attitude generation method for an industrial robot that can create an operation program for a robot that can obtain a stable work state by reducing the number.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problem, the industrial robot posture generation method of the present invention provides an accurate tool tip position and a rough tool when the tool posture of the teaching playback type industrial robot has one redundant degree of freedom. Prepare a motion program with multiple teaching points of posture, set a value that defines a degree of freedom other than the redundancy degree of freedom for each path between the teaching points, specify a work section from the motion program, and determine in advance Based on the specified conditions, a position for adding at least one point before and after the teaching point is set, and the robot operates using the specified value and the redundancy degree of freedom for the teaching point and the added front and rear point. When a possible tool posture candidate group is created and one tool posture is selected from the candidate points of the teaching point and the front and rear points, the teaching point includes Select a candidate for each robot axis position that minimizes the sum of all axes of the function of the difference between each robot axis position and each robot axis position during teaching as a teaching point after posture generation. Then, one candidate for each robot axis position that minimizes the sum of the functions of the difference between the robot axis positions of the teaching point after the posture generation and the robot axis positions in the candidate group at the previous point for all axes. The robot with the minimum sum of the functions of the difference between each robot axis position at the teaching point after posture generation and each robot axis position in the candidate group at the rear point for all axes is selected at the rear point of the teaching point. One candidate for each axis position is selected. The difference function may be the absolute value of the difference or the square of the difference.
[0006]
Another method of the present invention is an operation program having an accurate tool tip position and a plurality of teaching points of rough tool postures when the tool posture of a teaching playback type industrial robot has one redundancy degree of freedom. For each path between the teaching points, a value defining a degree of freedom other than the redundancy degree of freedom is set, a work section is specified from the operation program, and the teaching points are determined based on a predetermined condition. A position for adding at least one point is set before and after the tool point, and a tool posture candidate group is created for the teaching point and the added front and back points by using the specified value and the redundancy degree of freedom so that the robot can operate. When one tool posture is selected from the teaching point and the candidate group of the front and rear points, the teaching point is rotated from a tool coordinate at teaching to a certain tool coordinate in the candidate group at the teaching point. Roll used when converting. pitch. One tool coordinate candidate that minimizes the sum of the functions with the respective rotation angles of the yaw as a variable is selected as the post-generation teaching point, and the previous point of the teaching point is the previous point from the tool coordinate of the post-generation teaching point. Role used when rotating to some tool coordinates in a candidate group at a point. pitch. Select one tool coordinate candidate that minimizes the sum of the functions with each yaw rotation angle as a variable. At the rear point of the teaching point, from the tool coordinates of the teaching point after posture generation, The roll used when rotating to a certain tool coordinate. pitch. One tool coordinate candidate that minimizes the sum of the functions having the respective rotation angles of the yaw as variables is selected. In this method, the function may be an absolute value or a square of the variable.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples. Here, although arc welding is given as an example, the present invention is not limited to arc welding, TIG welding, spot welding, laser welding, laser cutting, sealing, cutting, grinding, deburring, spraying, etc. The same applies if you have In this embodiment, a case where a torch as shown in FIG. 4 is used will be described. At this time, the torch has one redundancy degree of freedom. That is, in the welding operation, the rotation direction around the Tz axis in FIG. 4 is not limited and may be any value. (Hereinafter, the Tz axis is referred to as a redundant degree of freedom axis, and Tx, Ty, and Tz are referred to as tool coordinates.)
First, an outline of the present invention will be described. When there is an operation program having the teaching points P0 to P3 as shown in FIG. 5, when the posture is generated using the present invention, it is as shown in FIG. In this example, the work section (welding section) is P0 to P3, where P0 is the welding start point, P3 is the welding end point, and the teaching points P1 and P2 between the welding start point and the welding end point are It is called a connection point. In FIG. 6, an approach point and an escape point are respectively added before the teaching point P0 and after the teaching point P3 (see Japanese Patent Application No. 8-87658), and the front point Ppre i and the rear point Pposti (i = 1, 2) has been added. The front and rear points are added on the path according to the interpolation method (straight line, arc, spline) (the movement trajectory of the tip of the torch when the robot moves from the teaching point to the teaching point is called a path) ( FIG. 6 illustrates the case of linear interpolation.)
[0008]
At the front and rear points and the teaching points, the postures are determined as follows (1) and (2).
(1) The posture is determined according to the set target angle and the corner angle.
・ The torch posture at P0 point and Ppre 1 point is the optimum welding posture in the P0-P1 section.
-The Ppost1 point and the Ppre2 point torch posture take the optimum welding posture in the P1-P2 section.
・ The torch postures at Ppost2 and P3 are the optimum welding postures in the P2-P3 section.
・ P1 takes an intermediate position between Ppre 1 and Ppost1.
・ P2 takes an intermediate posture between Ppre 2 and Ppost2.
(2) Select one optimum from the candidate group. The optimum welding posture is the posture when the aiming angle and the corner angle as shown in FIG. 3 are set, and the torch redundant degree of freedom axis Tz axis in FIG. 4 is set to the goal angle and the corner angle. Therefore, it is only necessary that the Tz axes coincide, and the Tx and Ty axis directions may be any direction. In the intermediate posture, the Tz axis of the intermediate posture is set as an intermediate point between the Tz axis of the Ppre i point and the Tz axis of the Pposti point, and the Tx and Ty axis directions of the intermediate posture may be arbitrary directions. Even if the optimum welding posture and intermediate posture are determined during posture generation, only the Tz axis is determined, and therefore a large number of candidates (referred to as candidate groups) can be listed by rotating the Tz axis. From this list of candidate groups, one optimal robot operation can be selected. As described above, by implementing the present invention, it is possible to generate a posture that is optimal for welding work and optimal for robot operation.
[0009]
Next, detailed embodiments of the present invention will be described. FIG. 1 is a flowchart for carrying out the present invention. In S001, operation program information is acquired. This operation program only needs to have multiple points of accurate tool tip position and rough tool posture, and was stored offline operation program, existing operation program in robot control panel, new operation program, or stored It is an operation program. In S002, a value that defines a degree of freedom other than the redundancy degree of freedom (hereinafter referred to as a prescribed value) is set for each path between teaching points. In this example, the corner angle and the aim angle are set. S003 is a process for when a plurality of welding sections exist in one operation program. The start point and end point of the welding section are sequentially searched from the initial position in the operation program, and the start and end points are found. If it comes to the final movement point of the operation program, the process goes to S010. In S004, when there are not three or more consecutive circular interpolation teaching points as movement commands in the work section at the teaching points in the operation program (when there are one or two continuous circular interpolation teaching points), Since an arc cannot be drawn, posture generation is not performed. In S005, it is determined whether the welding is the left side welding or the right side welding with respect to the traveling direction based on the teaching point coordinates of FIG. There are various types of determination methods, but for example, Japanese Patent Application No. 8-93400 is used. In S006, based on a predetermined condition, it is determined whether or not to add a point on the path before and after the teaching point, and an additional position is determined. In S007, a tool posture candidate group in which the robot can operate is created for all points in the welding section using the redundancy degree of torch. In S008, for all the points in the welding section, the teaching point is selected as a teaching point posture reflecting the position and posture at the time of teaching from the candidate group of postures, and the selected teaching point posture is used for the front and rear points. Select the reflected posture. In S009, an approach point and an escape point are added. There are various additional methods. For example, the method described in Japanese Patent Application No. 8-87658 is used. In S010, the result of posture generation is reflected in the operation program. With the procedure described above, it is possible to provide a robot posture generation method that can create an operation program that operates reliably after posture generation and obtains a stable work state.
[0010]
Specific examples are shown below.
<First Embodiment> FIG. 7 shows a detailed flowchart of S008. The point before the teaching point Pi is hereinafter referred to as Ppre i. The point after the teaching point Pi is hereinafter referred to as Pposti point. (I = 0 to N-1, where N is the number of teaching points in the work section)
S101 means the start of S008. In S102, the teaching points Pi from the welding start point to the welding end point are increased one by one, and it is determined whether i exceeds the end point or not. In S103, the candidate of the teaching point Pi is compared with the state at the time of teaching, and the candidate closest to the state at the time of teaching is adopted as a result after generating the posture of the teaching point Pi. Here, the closest means the difference between the j-axis motor pulse Tij at the time of teaching of the teaching point Pi and a motor pulse Cijk of a candidate among candidates (k is a candidate number for distinguishing each candidate) for each axis. That is, a candidate having a minimum value Jik obtained by summing absolute values for all axes is adopted as a teaching point posture generation result. That means
  Jik = Σj | Tij-Cijk |
  Jmin = MINk (Jik) (1)
However, Σj represents the sum of all motor axes (j = 0 to M−1), M represents the number of robot motor axes, and MINk represents the minimum value when k is changed. If the candidate number when taking Jmin is k1, it is adopted as Cijk1 as the motor pulse of the posture generation result.
[0011]
In S104, the candidate of Ppre i point is compared with the state of the teaching point after posture generation, and the candidate closest to the state of the teaching point after posture generation is adopted as the result after the posture generation of Ppre i point. Here, the closest means the absolute value of the difference between each axis between the j-axis motor pulse Cijk1 determined in S103 of the teaching point Pi and a candidate motor pulse Cpreijk in the Pprei point candidate for all axes. That is, the candidate having the minimum total value Jpre ik is adopted as the teaching point posture generation result. That means
  Jpre ik = Σj | Cijk1-Cpre ijk |
  Jpre min = MINk (Jik) (2)
If the candidate number k2 when taking Jpre min is assumed, the motor pulse of the posture generation result is adopted as Cpre ijk2. In S105, the Pposti point candidate is compared with the post-posture teaching point state, and the candidate closest to the post-posture teaching point state is adopted as the post-posture posture generation result. Here, the closest means the value obtained by summing up the absolute values of the differences for each axis between the j-axis motor pulse Cijk1 determined in S103 of the teaching point Pi and a candidate candidate motor pulse Cpostijk. That is, the candidate with the smallest Jpostik is adopted as the orientation generation result of the teaching point. That means
Jpostik = Σj | Cijk1-Cpostijk |
Jpost min = MINk (Jik) (3)
If the candidate number k3 when Jpost min is taken, the motor pulse of the posture generation result is adopted as Cpostijk3. S106 means the end of S008. If it does in the above way, operation of each motor axis will become small, and as a result, it will become difficult to apply load to a motor and operation of a robot in a connection point will become smooth.
[0012]
<No.3Example> No.3In this embodiment, the square of the difference is used instead of the difference between the robot axes of the first embodiment, and the equations (1), (2), and (3) are as follows. is there.
Jik = Σj (Tij-Cijk) 2 (4)
Jpre ik = Σj (Cijk1-Cpreijk) 2 (5)
Jpostik = Σj (Cijk1-Cpostijk) 2 (6)
[0013]
<No.2Example> No.2In the embodiment, in the processing contents of S103, S104 and S105 of the first embodiment, a roll. pitch. Other than using the yaw angleFirst embodimentAnd the same for each. In this way, an operation program can be obtained in which the amount of change in the tool posture at the connection point is reduced.
[0014]
more thanIn the example, the degree of influence of each axis is made uniform, but it is also possible to adjust the degree of influence of each axis by adding a weighting coefficient to the equations (1) to (6). For example, an expression obtained by adding a weighting coefficient to Expression (1) is
Jik = ΣjWj * | Tij−Cijk | (7)
Thus, the value of Wj can be adjusted by changing each j.
[0015]
<No.4~10Embodiment> FIG.4~10It is a flowchart of an Example and is related with the detail of S007 of FIG. S201 means the start of S007. In S202, i of the teaching point Pi from the welding start point to the welding end point is incremented one by one, and it is determined whether i exceeds the end point or not. In S203, it is determined whether the teaching point Pi is a welding start point, a connection point, or a welding end point. If the teaching point Pi is a welding start point, the process proceeds to S216. If the teaching point Pi is a connection point, the process proceeds to S204. move on. In S204,5According to the embodiment, the tangent lines on the i point of the two paths from the Pi-1 point to the Pi + 1 point are the same tangent line (the tangent vector on the Pi point of the path from the Pi-1 point to the Pi point, and The angle formed by the tangent vector on the point Pi from the point Pi to the point Pi + 1 is less than a certain value (for example, 5 degrees or less). The target angle and the corner angle of the two sections Are the same value, Ppre i point and Pposti point are not added. In such a case, since the tool coordinate Tz axis does not change, the front and rear points are not necessary, and the memory time for storing the calculation time and the front and rear points can be saved. Conversely, if the tangent lines are not the same, or if the aim angle and the corner angle are not the same, the front and rear points are added.
[0016]
In S2054According to the embodiment, if both the distance between Pi-1 and Pi points and the distance between Pi and Pi + 1 points are less than a certain value (for example, 20 mm or less), the points Pprei and Pposti are not added. In S2064If the distance between Pi-1 and Pi points is less than a certain value (for example, 20 mm or less) according to the embodiment, the Pprei point is not added and the Pposti point is added. In S207,4If the distance between Pi and Pi + 1 points is less than a certain value (for example, 20 mm or less) according to the embodiment, Pprei point is not added and Pprei point is added. By performing the processing of S205 to S207, when the interval between the teaching points is short and the section where the optimum welding posture can be taken is short, the memory space for storing the calculation time and the front and rear points can be saved, and the posture creation error can be reduced. It is difficult to get out. In S208,Each teaching pointSet the coordinatesP pre i pointThe tool coordinate Tz axis is determined, and the optimum welding posture of Ppre i point is created. The tool coordinate Tz axis is a redundant degree of freedom axis, and when generating a tool posture candidate, initial reference coordinates for rotating the tool coordinate Tz axis are determined as follows. Since the Pi point is a connection point, the Pi-1 point exists, the teaching point coordinate of the Pi-1 point is rotated around the X axis, and the teaching point coordinate of the i-1 point is rotated by the angle of advance to teach the i-1 point. The coordinates rotated once by the point coordinate Y axis as the center are further rotated by the target angle, and the coordinates rotated by 2 degrees thus obtained are further rotated 180 degrees around the Y axis of the coordinates rotated by 2 degrees. The coordinates rotated by 3 degrees are set as initial reference coordinates at the point Ppre i.
[0017]
When the Ppre i point position is determined in S209, the initial position of the Ppre i point is added as the distance from the teaching point on the motion interpolation line determined according to the interpolation method or as a ratio to the distance between the teaching points. Although there are various designation methods (for example, the method described in Japanese Patent Application No. 7-259230 is used),6And the second7The Ppre i point position is set again while checking whether the tool and the workpiece shape interfere with each other according to the embodiment. First6Examples of workpiece shape setting methods include CAD information and offline information.7As a work shape setting method according to the embodiment, there is a method for estimating a work shape from route data of an operation program, joint information, or the like. In S210, a tool posture candidate for Ppre i point is created. With respect to the tool posture in which the initial reference coordinate at the point Ppre i is rotated by a predetermined angle dTz with the Tz axis of the initial reference coordinate at the point Ppre i as the rotation center,10According to the embodiment, reverse conversion is sequentially performed (a method for calculating each robot axis position from the tool coordinates), and it is checked whether each robot axis position is within the operation range (range in which each robot axis can be operated). And check whether the part attached to the tool (conduit cable in the torch) does not interfere, and the ones that were not caught by the check are listed as candidates, and rotated by dTz from the initial reference coordinates at the point Ppre i until one rotation , Ppre i point tool posture candidates are created.
[0018]
In S211, first,Teaching pointA tangent vector from the teaching point Pi to the teaching point Pi + 1 on the first axis of coordinates (see FIG. 12. However, since FIG. 12 is an example at the time of linear interpolation, the tangent vector is a straight line from Pi to Pi + 1. ). The second axis is an outer product vector of the vector from the teaching point Pi to the point Pref set as the reference point and the first axis vector. At this time, if a reference point is not set, the second axis is the outer product vector of the vertical direction vector and the first axis vector. The i teaching point coordinates are set as the outer product vector of the first axis and the second axis on the third axis. further,P postiThe tool coordinate Tz axis of the point is determined, and the optimum welding posture of the Pposti point is created. The tool coordinate Tz axis is a redundant degree of freedom axis, and when generating a tool posture candidate, initial reference coordinates for rotating the tool coordinate Tz axis are determined as follows. First, the teaching point coordinate of the Pi point is rotated by the swift angle about the X axis of the teaching point coordinate of the Pi point. Next, the rotated point is rotated around the teaching point coordinate Y axis of the Pi point after the rotation. Further, it is rotated 180 degrees around the Y axis of the rotated coordinates. The coordinates obtained in this way are used as initial reference coordinates at the point Pposti.
[0019]
When determining the position of the Pposti point in S212, the position where the initial Pposti point is added is specified as a distance from the teaching point on the motion interpolation line determined according to the interpolation method, or as a ratio to the distance between the teaching points. (There are various designation methods. For example, the method described in Japanese Patent Application No. 7-259230 is used.)6And the second7The Pposti point position is set again while checking whether the tool and the workpiece shape interfere with each other according to the embodiment. First6Examples of workpiece shape setting methods include CAD information and offline information.7As a work shape setting method according to the embodiment, there is a method for estimating a work shape from route data of an operation program, joint information, or the like. In S213, a tool posture candidate for the Pposti point is created. With respect to the tool posture in which the initial reference coordinate at the Pposti point is rotated by a predetermined angle dTz with the Tz axis of the initial reference coordinate at the Pposti point as the rotation center,10According to the embodiment, reverse conversion is sequentially performed (a method for calculating each robot axis position from the tool coordinates), and it is checked whether each robot axis position is within the operation range (range in which each robot axis can be operated). And check whether the part (conduit cable in the torch) attached to the tool does not interfere, and those that were not caught in the check are sequentially listed as candidates, and rotated by dTz from the initial reference coordinates at the Pposti point until one rotation, Pposti point tool posture candidates are created. In S214Each teaching pointSet the coordinatesP iThe tool coordinate Tz axis of the point is determined, and an intermediate posture of the Pi point is created. The tool coordinate Tz axis is a redundant degree of freedom axis, and when generating a tool posture candidate, initial reference coordinates for rotating the tool coordinate Tz axis are determined as follows.
[0020]
First, the intermediate coordinates are rotated by a corner angle around the X axis of the intermediate coordinates between the teaching point coordinates of the Pi-1 point and the teaching point coordinates of the Pi point. Next, the center coordinate Y axis after the rotation is further rotated by the target angle. Further, it is rotated 180 degrees around the rotated Y axis. The coordinates thus obtained are set as initial reference coordinates at the Pi point. In S215, when the Pi point posture is determined, the initial Pi point posture is6And the second7The initial reference coordinates at the Pi point are set again while checking whether the tool and the workpiece shape interfere with each other according to the embodiment. First6Examples of workpiece shape setting methods include CAD information and offline information.7As a work shape setting method according to the embodiment, there is a method for estimating a work shape from route data of an operation program, joint information, or the like. In S216,Each teaching pointSet the coordinatesP iThe tool coordinate Tz axis of the point is determined and the optimum welding posture of the Pi point is created. The tool coordinate Tz axis is a redundant degree of freedom axis, and when generating a tool posture candidate, initial reference coordinates for rotating the tool coordinate Tz axis are determined as follows. First, the teaching point coordinate of the Pi point is rotated by the swift angle about the X axis of the teaching point coordinate of the Pi point. Next, the rotated teaching point coordinate Y axis is further rotated by the target angle. Further, it is rotated 180 degrees around the rotated Y axis. The coordinates thus obtained are set as initial reference coordinates at the Pi point.
[0021]
In S217,Each teaching pointSet the coordinatesP iThe tool coordinate Tz axis of the point is determined and the optimum welding posture of the Pi point is created. The tool coordinate Tz axis is a redundant degree of freedom axis, and when generating a tool posture candidate, initial reference coordinates for rotating the tool coordinate Tz axis are determined as follows. First, the teaching point coordinate of the Pi point is rotated by a swift angle about the X-axis of the teaching point coordinate of the Pi-1 point. Next, the coordinate rotated about the teaching point coordinate Y-axis of the Pi-1 point is further rotated by a target angle. Further, it is rotated 180 degrees around the Y axis of the rotated coordinates. The coordinates thus obtained are set as initial reference coordinates at the Pi point. In S218, a tool posture candidate at the teaching point Pi is created. With respect to the tool posture in which the initial reference coordinate at the Pi point is rotated by dTz with the Z axis of the initial reference coordinate at the Pi point as the rotation center,10According to the embodiment, the reverse conversion is sequentially performed to check whether each robot axis position is within the operation range, whether the robot arm, the tool, and the part attached to the tool do not interfere with each other. Candidates are made as tool candidates for the teaching point Pi point until it rotates one dTz from the initial reference coordinate at the teaching point Pi until one rotation. S219 means the end of S007. Here4~10Although the example which implemented the Example simultaneously was described, of course, you may use separately.
[0022]
<No.11~13Embodiment> FIG.11Example and No.133 is a flowchart showing an embodiment, in which S304 is inserted between S003 and S004 in FIG. 1, and S311 is inserted after S009. In S304, when there is the same point in the welding section determined in S003 (when the positions of the two points are in the vicinity and within a certain range, for example, within 1 mm), the same point group is selected. The first point is chosen as the representative (any of the points can be chosen as the representative). The second12In the invention of the embodiment, as another method for determining the same point, the case where the tool posture and the position are both the same is used as the same point. In S311, if there is a section set as a section where posture generation is not performed, the added front and rear points in the section are deleted, and the posture of the teaching point generated posture is returned to the posture at the time of teaching. FIG. 10 shows the result after posture generation when a section in which posture generation is not performed is set, and will be described with reference to FIG. Although the postures P2, Ppost2, teaching point P3, and escape point are generated, the points Ppost1 and Ppre2 are not added, and the teaching point P1 and the teaching point P2 are postures at teaching. Here, the second11~13Although the example which implemented the Example simultaneously was described, of course, you may use separately.
[0023]
<No.14Embodiment> FIG.14It is a flowchart showing an Example, and the determination whether a candidate exists is added to FIG. First14According to the embodiment, when there is no candidate at the Pi point, the Ppre i point, or the Pposti point, if the front and rear points are not added, the front and rear points are not added. Inform the user that the group could not be created. There are various types of transmission means. For example, a point on the display of the teaching tool is displayed. S401 means the start of S008. In S402, the teaching point Pi from the welding start point to the welding end point is increased one by one, and it is determined whether i exceeds the end point or not. In S403, it is determined whether there are one or more candidates at the teaching point Pi. In S404,14According to the embodiment, since there is no candidate at the teaching point Pi, the posture after the posture generation is set as the tool posture at the time of teaching. At this time, information that “the posture cannot be generated and the tool posture at the teaching point Pi is the same as the tool posture at the time of teaching” is also transmitted to the user. S405 is the same as S103.
[0024]
In S406, it is determined whether there are one or more candidates at Ppre i point. In S407,14According to the embodiment, since there is no candidate at Ppre i point, Ppre i point is not added. At this time, information that “the posture cannot be generated and the Ppre i point is not added” is also transmitted to the user. S408 is the same as S104. In S409, it is determined whether or not there are one or more candidates at the Pposti point. In S410,14According to the embodiment, since there is no candidate at the Pposti point, no Pposti point is added. At this time, information that “the posture cannot be generated and no Pposti point is added” is also transmitted to the user. S411 is the same as S211. S412 means the end of S008. As mentioned above, although the Example which applied this invention to arc welding was mentioned and demonstrated, this invention is not limited at all by this.
[0025]
【The invention's effect】
As described above, according to the present invention, it is possible to generate a posture that is optimal for various operations performed by an industrial robot and that is optimal as a robot operation, thereby simplifying teaching operations and improving work efficiency. improves.
[Brief description of the drawings]
FIG. 1 is a flowchart showing posture generation processing of the present invention.
FIG. 2 is an explanatory diagram of a conventional technique.
FIG. 3 is an explanatory diagram of a target angle and a corner angle.
FIG. 4 is an explanatory diagram showing a tool shape and a tool coordinate system of the present invention.
FIG. 5 is an explanatory diagram of an operation program having teaching points P0 to P3 before posture generation according to the present invention.
FIG. 6 is an explanatory diagram of an operation program after posture generation according to the present invention.
FIG. 7 is a flowchart of detailed processing of S008 in FIG.
FIG. 8 is a flowchart of detailed processing of S007 in FIG.
FIG. 911Example and No.13It is a flowchart showing an Example.
FIG. 10 is an explanatory diagram of a posture generation result when a section in which posture generation is not performed is set.
FIG. 1114It is a flowchart showing an Example.
FIG. 12 is an explanatory diagram of i teaching point coordinates of a teaching point Pi.

Claims (14)

When the teaching posture of the industrial robot of the teaching playback method has one redundancy degree of freedom,
Prepare an operation program with multiple teaching points for accurate tool tip position and rough tool posture.
For each path between the teaching points, set a value that defines a degree of freedom other than the redundancy degree of freedom,
A work section is identified from the operation program, and a position for adding at least one point before and after the teaching point is set based on a predetermined condition.
For the teaching point and the added front and rear points, a tool posture candidate group is created that allows the robot to operate using the specified value and the redundancy degree of freedom,
When one tool posture is selected from the candidate group of the teaching point and the front and rear points, the teaching point has a function of the difference between each axis position of the robot in the candidate group at the teaching point and each axis position of the robot at teaching. One candidate for each axis position of the robot with the minimum value for the total of the axes is selected as the post-pose generation teaching point, and at the previous point of the teaching point, the robot axis position of the post-posture generation teaching point and the candidate group at the previous point Select one candidate for each robot axis position that minimizes the sum of the functions of the differences from each robot axis position for all axes.
At the rear point of the teaching point, each axis of the robot where the sum of all the axes of the difference function between the robot axis position of the teaching point after posture generation and the robot axis position in the candidate group at the rear point is the minimum. A method for generating an attitude of an industrial robot, wherein one candidate position is selected. When the teaching posture of the industrial robot of the teaching playback method has one redundancy degree of freedom,
Prepare an operation program with multiple tool points for accurate tool tip position and rough tool posture.
For each path between the teaching points, set a value that defines a degree of freedom other than the redundancy degree of freedom,
A work section is identified from the operation program, and a position for adding at least one point before and after the teaching point is set based on a predetermined condition.
For the teaching point and the added front and rear points, a tool posture candidate group is created that allows the robot to operate using the specified value and the redundancy degree of freedom,
When selecting one tool posture from the teaching point and the candidate group of the front and rear points, the teaching point is a roll used when rotationally converting from a tool coordinate at teaching to a certain tool coordinate in the candidate group at the teaching point. pitch. Select one tool coordinate candidate that minimizes the sum of the functions with each yaw rotation angle as a variable, as a teaching point after posture generation,
In the previous point of the teaching point, a roll used when rotationally converting the tool coordinate of the teaching point after posture generation to a certain tool coordinate in the candidate group at the previous point. pitch. Select one tool coordinate candidate that minimizes the sum of the functions with each yaw rotation angle as a variable,
At the rear point of the teaching point, a roll used for rotational conversion from the tool coordinates of the teaching point after posture generation to a certain tool coordinate in the candidate group at the rear point. pitch. A method for generating an attitude of an industrial robot, wherein one candidate of tool coordinates that minimizes the sum of functions having respective rotation angles of yaw as variables is selected.   The industrial robot posture generation method according to claim 1, wherein the function is an absolute value or a square of the variable.   The predetermined condition is a step of obtaining a path section distance determined according to interpolation between two consecutive teaching points in the work section, and determining whether the distance is equal to or less than a preset value. The attitude of the industrial robot according to any one of claims 1 to 3, including a step and a step of not adding front and rear points in the path if the distance is equal to or less than the preset value. Generation method.   The predetermined condition is that a front tangent vector determined according to a front path of a connection point which is a teaching point other than a start point and an end point in a work section and a rear tangent vector determined according to a rear path are set in advance. The point before and after the connection point is not added if the same direction within the range and the specified value at the front point and the rear point are the same value. The attitude generation method for industrial robots described in 1.   The predetermined condition is that when determining the position of the front and rear points, a workpiece shape is set, and the positions of the front and rear points are determined in consideration of interference between the workpiece and the tool. The attitude | position generation method of the industrial robot described in any one of thru | or 3.   The predetermined condition is that when determining the position of the front and rear points, set work information, set a teaching point in the operation program and a reference point that can be set for each path, the workpiece information, the teaching point, The workpiece shape is estimated from the reference point, and the positions of the front and rear points are determined in consideration of interference between the workpiece shape and a tool. Industrial robot posture generation method.   4. The tool posture candidate group is created by setting a workpiece shape at a teaching point and determining the posture of the teaching point in consideration of interference between the workpiece and the tool. An attitude generation method for an industrial robot described in any one of the items.   When creating the tool posture candidate group, the workpiece information is set at the teaching point, the teaching point and the reference point in the operation program are set, and the workpiece shape is determined from the workpiece information, the teaching point, and the reference point. 4. The method for generating an attitude of an industrial robot according to claim 1, wherein the position of the teaching point is determined in consideration of interference between the workpiece shape and the tool.   The method for generating an attitude of an industrial robot according to any one of claims 1 to 3, wherein when generating the tool attitude candidate group, a candidate is generated in consideration of a restriction on an operation range of the robot. .   When the distance between a plurality of consecutive points is smaller than a preset value at a teaching point in the operation program, the points are the same, one of the points is a representative point, and the representative point is used when generating a posture. The industrial robot posture generation method according to any one of claims 1 to 3, wherein:   If the teaching point in the operation program has a distance between a plurality of consecutive points smaller than a preset value and a difference in posture is also less than a preset range, the same point is set and one of the plurality of points is set. 4. The industrial robot posture generation method according to claim 1, wherein the representative point is used as a representative point, and the representative point is used when generating the posture.   A part of the work section in the operation program can be set as a section that does not generate a posture, and in a section that is set as a section that does not generate a posture, the front and rear points in the section are added when the posture is generated 4. The attitude generation method for an industrial robot according to any one of claims 1 to 3, wherein the attitude of the teaching point in the section is the same as the attitude at the time of teaching.   If no tool posture candidate group was created, if it was a front / rear point, no front / rear point was added, and if it was a teaching point, it was the same as the posture at the time of teaching, and it was impossible to create a candidate group The method for generating an attitude of an industrial robot according to any one of claims 1 to 3, characterized in that:

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