JP2010142910A - Robot system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a robot system reducing a teaching burden of assembling and fitting work, performing efficient work by improving precision of fitting work, and enhancing robustness against environmental changes during teaching work and regeneration operation. <P>SOLUTION: A robot controller 102 is provided with a posture calculating part 1024 which develops a work program for performing fitting work while avoiding an obstacle from respective positions of a workpiece gripping point and a fitting point which have been temporarily taught and a route point between a workpiece gripping point and the fitting point, a posture of an end effector 104 at the workpiece gripping point and the fitting point, and a position of the obstacle existing around the robot 101, and which stores the developed work program in a teaching data storage part 1023. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an industrial robot (hereinafter simply referred to as “robot”) system, and more particularly to a robot system related to teaching and reproduction of operations such as parts assembly by a robot.

The assembly process of parts for cars and home appliances often includes a work for fitting workpieces. Therefore, when an assembly process including such a fitting operation is automated and labor-saving using a robot, it is necessary to teach the robot the fitting operation by some method. The method of teaching assembly / fitting work by the robot can be divided into online teaching and offline teaching.
As an on-line teaching method, for example, in Patent Document 1, an actual robot is given a work, an operator guides the robot to take an appropriate position and orientation, and then a fitting operation is actually performed by force control or the like. An example of registering the position of the fitted state is disclosed.
Further, as an off-line teaching method, there is a method in which a work program is created in advance by an external personal computer or the like, and is transferred to a robot controller for playback operation.
Furthermore, as a method combining online teaching and offline teaching, there is also a method of teaching offline by measuring a workpiece with a distance measuring sensor to recognize a shape.

However, in the online teaching, the teaching work is complicated because the robot can take a plurality of postures with respect to the same teaching position in the robot having the redundancy degree of freedom when teaching the assembly and fitting operation by the robot with high accuracy. It is. Further, when the regenerative operation is performed, there may be a problem that the movement amount of each axis is large and takes a long time when taking the taught posture. In such a case, re-teaching is required to optimize the operation.
On the other hand, in the offline teaching, there is a case where the origin of the teaching data created off-line and the actual robot origin are misaligned, and it is difficult to correct the teaching point position of the work program created in advance. Also, in operations involving contact, such as assembly operations, there are problems that misalignment occurs due to positioning errors and workpiece machining errors during playback operation, and the operation fails due to interference with peripheral devices that did not exist during teaching. is there.

Therefore, for example, in Patent Document 2, as a method for teaching the teaching position with high accuracy by online teaching, a position detecting means for detecting the position of the workpiece is provided on the end effector of the robot, and the position detecting means has a measuring beam in the position detecting area. In this example, the position information of the workpiece is acquired based on diffusely reflected light or regular reflected light returning from the position detection region.
In Patent Document 3, as a method for teaching a teaching position with high accuracy by off-line teaching, a distance measuring unit for measuring a distance to a target point on a workpiece in a non-contact manner is provided on the wrist of the robot and is measured by the distance measuring unit. The distance data obtained from the distance is converted into a visual image instruction path and displayed on the screen, and the desired position indicated by the operator is converted into position data and specified. An example of acquiring is disclosed.
In Patent Documents 4 and 5, as a method for solving the origin deviation in offline teaching, an operator guides a pseudo robot provided with a sensor unit for detecting contact with an object at a tip portion by direct teaching, By using an operation mechanism that teaches machining path data by sequentially inputting workpiece shape data by bringing the sensor part into contact with the surface of the machine, import these data into an offline teaching device, check operations, edit teaching points, An example of performing additional teaching of work conditions on the screen of an offline teaching device and a method of teaching directly for teaching positions that require high accuracy, while enabling work programs and teaching positions created offline An example of a robot simulation system that easily corrects an error of a teaching position by using it is disclosed.
Further, Patent Document 6 discloses an example in which an insertion position is searched and inserted as a method for solving a positional shift during regeneration operation.
Further, in Patent Document 7, as a method for solving interference with peripheral devices during the reproduction operation, it is detected whether the robot passes through the interference region and moves outside the interference region, and moves to outside the interference region. In this case, an example of automatically creating a detour path and detouring the robot is disclosed.

JP-A-8-194521 (page 3, FIG. 1) JP-A-5-309590 (4th page, FIG. 1) JP-A-6-348330 (page 3, FIG. 1) Japanese Patent Laid-Open No. 7-20925 (page 3, FIG. 1) JP 2001-51713 A (page 3, FIG. 1) Japanese Patent Laying-Open No. 2004-167651 (page 7, FIG. 2) Japanese Patent Laid-Open No. 61-147307 (2nd page, FIG. 1)

However, as in Patent Document 2, the position detection means for detecting the position of the workpiece is provided on the end effector, and the method of acquiring the workpiece position information can detect the workpiece position with high accuracy. In addition, there is a problem that the positional relationship (position and posture) between the end effector and the workpiece cannot be taught with high accuracy due to the link dimension error and the origin error of the robot.
Further, as in Patent Document 3, in the method in which distance data obtained from the distance measured by the distance measuring means is displayed on the screen as a visual image instruction path and the operator instructs, the operator instructs There is a problem that it takes time and it takes an enormous amount of time to recognize the shape of the workpiece.
Also, as in Patent Document 4, in the method of creating teaching data by direct teaching using a pseudo robot and making it contact with a work, if the axis configuration of the operating mechanism is different from that of the actual robot, input is made by the operating mechanism. There was a problem that the posture could not be taken by the robot.
Further, in the method of combining the work program generated offline and the direct teaching of the teaching position as in Patent Document 5, when the approach posture generated offline is not suitable for the actual environment, the teaching position generated offline is used. There was a problem that the robot could not reach.
Further, as in Patent Document 6, in the method of searching and inserting the insertion position during the reproduction operation, there are problems that it takes time for the search and that it is difficult to determine the search direction and the movement amount.
Further, as disclosed in Patent Document 7, when a robot moves through the interference area and moves to the outside of the interference area at the time of the reproduction operation, the detour path is automatically created to bypass the robot online. There was a problem that it was not possible to deal with when this occurred.
The present invention has been made in view of such problems, and can reduce the burden of teaching assembly and fitting work, improve the accuracy of fitting work and make the work more efficient, and can be performed during teaching work and during regenerative operation. An object of the present invention is to provide a robot system capable of improving robustness against changes in the environment of time.

In order to solve the above problems, the present invention is configured as follows.
According to the first aspect of the present invention, there is provided a robot having a plurality of joints and having an end effector attached to a tip portion thereof, a teaching data storage unit for storing teaching data and a work program of the robot, and the robot based on the work program A robot controller including a command generation unit that generates an operation command to the robot, a servo control unit that drives a servo motor of each joint of the robot by the operation command, and a teaching device connected to the robot control device The robot controller performs an operation of gripping the workpiece placed at the first predetermined position by the end effector and fitting the workpiece to the second predetermined position. And the fitting point, each position of the via point between the workpiece gripping point and the fitting point, and the workpiece grip A posture for generating a work program for fitting by avoiding the obstacle from the posture of the end effector at the point and the fitting point and the position of the obstacle around the robot, and storing it in the teaching data storage unit An arithmetic unit is provided.

  According to a second aspect of the present invention, the robot is an articulated robot having redundant degrees of freedom, and the posture calculation unit determines the posture of the end effector and the redundant degrees of freedom when generating the work program. It is characterized by.

  According to a third aspect of the present invention, the teaching data storage unit includes a workpiece gripping point and a fitting point that are provisionally taught, each position of a via point between the workpiece gripping point and the fitting point, and the workpiece. The posture of the end effector at a gripping point and a fitting point and the position of an obstacle existing around the robot are stored as the teaching data.

  According to a fourth aspect of the present invention, the teaching data storage unit acquires the position of an obstacle existing around the robot from CAD data of an environment in which the robot operates.

  According to a fifth aspect of the present invention, the robot includes a workpiece position detection sensor at a distal end portion, and the posture calculation unit has the first predetermined position acquired by the workpiece position detection sensor when generating the work program. The position of the workpiece gripping point that has been tentatively taught is corrected according to the position of the placed workpiece, and the tentatively taught fitting point position is determined by the second predetermined position acquired by the workpiece position detection sensor. It is characterized by correction.

  According to a sixth aspect of the present invention, when the posture calculation unit generates the work program, between the corrected work gripping point and the via point, and between the via point and the corrected fitting point. Interpolation is performed at a plurality of points, and the end effector and the redundancy degree of freedom are determined for the plurality of interpolation points.

  According to a seventh aspect of the present invention, the robot controller compares a command position obtained by forward-converting a position command to each axis of the robot with a feedback position obtained by forward-converting a position feedback value by the encoder of the servo motor. A work status determination unit that determines that the operation has failed if the error exceeds a preset threshold value, and determines that the operation has failed in the fitting during the regeneration operation, the work position detection sensor The second predetermined position is detected, and the fitting operation is performed again on the detected position.

  The invention described in claim 8 is characterized in that when the work situation determination unit determines that the work has failed, it is presented to the operator via the teaching device.

  According to a ninth aspect of the present invention, the robot includes an obstacle position detection sensor that measures the position of a surrounding obstacle on the arm, and the posture calculation unit detects the obstacle position during the reproduction operation of the work program. An unknown obstacle in the vicinity of the robot is detected by a sensor, and the work program is dynamically corrected.

According to the first to third aspects of the invention, the operator can automatically generate a work program only by teaching the rough position and orientation of the end effector and the position of the obstacle, and can teach the assembly and fitting work. The burden can be reduced.
In addition, there is an effect that an operator can teach a robot having redundant degrees of freedom without considering the posture of the robot.
According to the fourth aspect of the present invention, the burden of the operator's teaching can be reduced by acquiring the position of the obstacle from the CAD data.
According to the fifth and sixth aspects of the invention, since the work position and the fitting position are detected by the work position detection sensor and the work program is generated, the accuracy of the fitting work can be improved and the work can be made efficient. it can.
According to the seventh aspect of the present invention, when the work situation determination unit determines that the work has failed during the regeneration operation, the fitting operation is automatically performed again based on the detection result of the work position detection sensor. Therefore, the success probability of fitting can be increased and the work can be made efficient.
According to the eighth aspect of the invention, the operator can easily grasp the situation of the fitting work.
According to the ninth aspect of the present invention, since an unknown obstacle position in the vicinity of the robot arm is detected by the obstacle position detection sensor and the operation path is corrected, there is an unknown obstacle during the reproduction operation. Even if it can respond, it has the effect.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram of a robot system according to a first embodiment of the present invention. In the figure, 101 is a robot having redundancy degrees of freedom, 102 is a controller for controlling the operation of the robot 101, 103 is a teaching device having operation buttons and numerical buttons and a display for operating each axis of the robot 101, and 104 is a robot. An end effector (herein referred to as a gripper) disposed at the end of the robot, 105 is a workpiece, 106 is a workpiece position detection sensor disposed on or around the end effector 104, and 107 is an obstacle disposed on the arm of the robot 101. It is an object position detection sensor.
In the controller 102, a teaching data storage unit 1023 for storing a robot work program and teaching data, a command generation unit 1021 for generating a robot operation command based on the work program, and each axis servo of the robot based on the operation command A servo control unit 1022 for driving the motor and a posture calculation unit 1024 for automatically calculating the optimum arm posture at each teaching point position of the robot from information such as teaching data are provided.
In FIG. 1, the posture calculation unit 1024 is built in the controller 2. However, the posture calculation unit 1024 is connected to the controller 2 through a communication line such as a LAN as a personal computer separate from the controller 2. It is also good.

The process from the teaching work of the assembly / fitting work using the robot system to the regeneration operation will be described.
In the teaching work stage, the operator presses an operation button corresponding to each axis of the robot arranged on the teaching device 103 to operate the robot and guide it, or a force sensor arranged near the end effector 104 (FIG. The robot is guided by direct teaching in which stress is applied to the robot (not shown) and the robot is guided by force control.
The robot has redundant degrees of freedom, and even when the position and orientation of the end effector are uniquely determined, a plurality of postures corresponding to the elbow can be taken. Therefore, while it is possible to avoid interference between the robot and peripheral devices without changing the position and orientation of the end effector, it is difficult to find an optimal posture. In addition, the position and orientation of the end effector may be difficult to accurately teach because the operator cannot sufficiently visually observe the work in a narrow portion.
Therefore, in this robot system, only a rough position is taught by the robot guidance by the operator, the detailed position is acquired by the work position detection sensor as described later, and the posture is automatically calculated by the posture calculation unit as described later. Take the steps of letting you decide.

A detailed teaching method will be described with reference to FIG. In FIG. 2A, an example is shown in which the male connector 1052 disposed on the layout pallet 110 is gripped by the end effector 104 and fitted to the female connector 1051 in the housing 109. FIG. 2A shows the robot 101 in a simplified manner so that its axis configuration can be easily grasped.
A plurality of known obstacles 1081 and 1082 exist in the housing 109. First, the operator guides the end effector 104 to the layout pallet 110 by the direct teaching or the indirect teaching described above. After guiding to the layout pallet 110, the male connector 1052 may be actually gripped by an end effector (gripper) and the position may be registered as a teaching position. However, the robot posture may be adjusted to an appropriate approach posture, Accurate gripping of the connector at the gripping center of the gripper takes time when the skill level of the operator is low. Therefore, here, the connector acquisition position A on the layout pallet is tentatively taught without actually holding the connector and taking a posture that is rough enough not to touch the obstacle.
For example, the closed gripper is taught to be located in a space several cm above the center of the male connector 1052. At the same time, the operator uses the teaching device 103 or the like to set the connector gripping direction (end effector posture).

Next, the positions of known obstacles 1081 and 1082 in the housing 109 and the via position B for avoiding the obstacle are taught. In this embodiment, for the sake of simplicity of explanation, the number of via points is only one, but the number of via points may be plural depending on the number and arrangement of obstacles.
In the case where the position and size of a known obstacle can be taken into the controller 102 based on the CAD data of the housing 109 or the like, teaching about the obstacle can be omitted. For example, the CAD data is taken into the controller 102 as follows. First, the teaching data storage unit 1023 captures CAD data, extracts the vertex of the obstacle from the CAD data, and defines the position and size of the obstacle 1082 in the robot coordinate system. For example, when the obstacle 1082 is a rectangular parallelepiped, the eight vertices are provided. 10821 to 10824 shown in FIG. 2A show a part of the apex of the obstacle 1082.
When the obstacle information cannot be acquired by CAD data or the like, the robot is actually operated in the same manner as the connector acquisition position A to guide the end effector 104 to the position of the top of the obstacle or the surface, and the teaching data storage unit The information about the obstacle is stored in 1023.

Subsequently, the end effector 104 is guided to a position near the middle between the connector acquisition position A and the female connector 1051 without interfering with the obstacle position, and is registered in the teaching data storage unit 1023 as a via position B.
When CAD data or the like can be used, the operator operates the teaching device 103 to display the position of the obstacle, the connector acquisition position A, and the female connector 1051 on the display. An appropriate position may be input as a numerical value as the via position B. Alternatively, a position (area) that is a predetermined distance away from the obstacle is automatically obtained in advance, and a curve that does not pass through this area while connecting the connector acquisition position A and the female connector 1051 (for example, an nth-order curve where n is 2 or more) And a point on the curve may be registered as the via position B.

Finally, in order to teach the connector assembly fitting position C, the end effector 104 is guided to teach a space several cm above the center position of the female connector 1051 as in the case of the connector acquisition position A. . At the same time, the operator uses the teaching device 103 to set the connector insertion direction (end effector posture).
Information on the connector acquisition position A, the via position B, the assembly fitting position C, and the connector gripping direction at the point A and the connector insertion direction at the point C are stored in the teaching data storage unit 1023. Further, as described above, information related to the obstacle is also stored in the teaching data storage unit 1023, and the position teaching operation is completed.

  After the position teaching work is completed, the posture teaching work is automatically performed. In the posture calculation unit 1024, information on the connector acquisition position A, the via position B, the assembly fitting position C, the connector gripping direction at the point A, and the connector insertion direction at the point C stored in the teaching data storage unit 1023 is known. Based on the information on the obstacles (1081 and 1082), the posture of the arm at each teaching point position is determined so that the posture change and the speed change of the robot are reduced during actual work.

Specifically, the posture of the end effector at each of the positions A and C is uniquely determined from the information on the connector acquisition position A and the connector gripping direction, the assembly fitting position C, and the connector insertion direction. The axis of redundant freedom (here, the elbow angle) has a large distance from the obstacles in the connector acquisition position A and assembly fitting position C (obstacle 1082 in A and obstacle 1083 in C). Take a posture.
In FIG. 2A, ELBOW1 (solid line) and ELBOW2 (dotted line) are shown as examples of the elbow angle at the connector acquisition position A. Since the robot 101 has redundant degrees of freedom, the axis between the second axis (J2) and the sixth axis (J6) from the base of the robot can take a plurality of postures, and the elbow point position is also associated with this, for example, It changes like ELBOW1 and ELBOW2.
FIG.2 (b) is DD sectional drawing of Fig.2 (a). As shown in Fig. 2 (b), the elbow point is on the elbow point circle (circle drawn by the elbow point) including the elbow point of ELBOW1 and ELBOW2 around the line connecting the second axis (J2) and the sixth axis (J6). Can be taken freely. Here, E is the center position of the elbow point circle on the line connecting the second axis (J2) and the sixth axis (J6).
The command generation unit holds data such as the link length between each axis of the robot as parameters for calculation of inverse kinematics when generating a command to be output to each axis of the robot, but the posture calculation unit 1024 By referring to these data, the elbow position is calculated, and it is confirmed whether there is any interference with the obstacle.
In the case of ELBOW2, since the elbow interferes with the layout pallet 110 which is an obstacle in the vicinity, ELBOW1 having a posture with a greater distance from the layout pallet 110 is selected. Actually, the elbow position (angle) closest to the obstacle in the elbow point circle can be selected from a range of 90 degrees to 270 degrees where the probability of interference is small when the position is 0 degrees. Here, an angle of 180 degrees is selected.

  The end effector posture and elbow angle at the via position B are connected from the connector acquisition position A to the via position B by connecting the end effector posture and the elbow angle at the connector acquisition position A and the assembly fitting position C. Further, the posture change and speed change of the robot during movement from the via position B to the assembly fitting position C are made small.

FIG. 3 shows a method of determining the attitude of the end effector at the via position B. In FIG. 3, a portion between J2 and J6 of the robot is omitted.
The end effector posture at the connector acquisition position A and the assembly fitting position C can be uniquely determined from the connector gripping direction and the connector insertion direction, but the end effector posture to the via position B is not uniquely determined.
Therefore, the posture change (θc−θa) from the posture angle θa of the connector acquisition position A to the posture angle θc of the assembly fitting position C with respect to the Z axis of the robot coordinate system is determined by the operation of the connector acquisition position A and the assembly fitting position C. The posture of the end effector at the via position B can be obtained by equally dividing and assigning according to the distance along the route (posture A1 to A3 in FIG. 3). Similarly, the attitude angle of the end effector from the via position B to the assembly fitting position C is also determined by equally dividing (postures B1 to B2 in FIG. 3).

On the other hand, the elbow angle at the via position B is paid out by equally dividing the elbow angle from the connector acquisition position A and the assembly fitting position C according to the distance along the operation path in the same manner as the end effector posture determination method. Can be obtained. However, if there is an obstacle in the middle of the connector acquisition position A and the via position B, the elbow angle is 180 ° so as to avoid the obstacle as shown in the example of the elbow angle at the connector acquisition position A in FIG. It is necessary to equally divide the elbow angle at the connector acquisition position A and the elbow angle, and similarly equally divide the elbow angle at the via position B again.
For example, if the elbow angle is 180 ° in the posture of A2 in FIG. 3 and the elbow point interferes with the obstacle 1083, the elbow angle is changed to 90 ° or 270 °. However, the elbow angle in this case is not limited to 90 ° or 270 °, and can be selected in the range of 90 ° to 270 ° (except around 180 °) as long as it does not interfere with an obstacle.

  Here, importance is attached to reducing the posture change and the speed change of the robot when determining the posture of the end effector and the elbow angle, but it may be important to reduce the speed change of each axis and elbow. Specifically, when the posture of the arm is determined by the posture calculation unit 1024, the weighting of the possibility of interference with the obstacle is reduced, and the evaluation function emphasizes the small amount of change in the speed of each axis and elbow. The elbow angle is determined using.

  Based on the posture and elbow angle of the end effector at each position obtained by the posture calculation unit 1024 in this way, an operation command along a series of operation paths (single-dotted lines in FIG. 3) is generated in the command generation unit 1021. Is stored in the teaching data storage unit 1023 as a work program, and the posture teaching work is terminated.

After the posture teaching work is completed, the robot operates to automatically perform work (connector) acquisition / fitting position correction work. In this method, the position data of the connector acquisition position A and the assembly fitting position C, which are roughly taught, are acquired in detail.
This will be specifically described with reference to FIG.
The robot moves to the connector acquisition position A according to the work program stored in the teaching data storage unit 1023. Since the previously taught position is several cm above the male connector 1052 as described above, the robot stops at that position. From the position, the position of the male connector 1052 is measured by the work position detection sensor 106 disposed on or around the end effector 104, and the measurement result and the current position of the robot (connector acquisition position A) are synthesized. A detailed position A ′ of the male connector 1052 is obtained.
When the workpiece position detection sensor 106 is a one-dimensional laser sensor, the position of the male connector 1052 can be acquired by moving the end effector 104 in the horizontal direction from above the male connector 1052 and performing scanning by the workpiece position detection sensor 106. It is. The position of the male connector 1052 may be acquired using a camera as the work position detection sensor 106. Similarly, for the assembly fitting position C, detailed position data C ′ is acquired using the measurement result of the workpiece position detection sensor 106. These measurement results and position correction amounts may be displayed on the display of the teaching device 103 and presented to the operator.

Using the position data of the connector acquisition detailed position A ′ and the assembly fitting detailed position C ′ acquired by the work position detection sensor 106 and the dimension data of the female connector 1051 and the male connector 1052, the teaching data storage unit 1023. The work calculation program is recalculated by the posture calculation unit 1024. At this time, the final holding position of the male connector 1052 considering the fitting depth and the fitting position of the female connector 1051 and the male connector 1052 are obtained based on the dimensional data of the connector. Data of the connector acquisition position A and the assembly fitting position C, which are rough approach positions, are also corrected based on the measurement result of the work position detection sensor 106.
As a result, a new work program based on the detailed position data is created and stored in the teaching data storage unit 1023, and the work (connector) acquisition / fitting position correction work is completed, and the regenerative operation is possible.
Here, a plurality of teaching points between A ′ to B and B to C ′ are necessary during the regeneration operation. Since the position and orientation of the end effector and the elbow angle at that time at the detailed position A ′, via position B, and detailed position C ′ of assembly fitting are obtained by the method described above, these intermediate teaching points Are generated by interpolating them. Basically, the paths that connect A ′ to B and B to C ′ in the shortest distance are selected, but the path (position) so that the end effector posture change and elbow angle change do not increase before and after the via position B. Is fixed. Specifically, the posture change is reduced by connecting the connector acquisition position A ′, the via position B, and the assembly fitting position C ′ through an operation path close to an arc shape.

  According to the present invention, when teaching assembly fitting work (and regenerating operation) by a robot having a degree of freedom of redundancy, the operator first determines the posture of the end effector with respect to teaching the workpiece gripping position and the workpiece fitting position. After teaching only the position of the end effector without considering the elbow angle of the robot and the robot, the end effector posture and elbow angle can be generated by inputting the gripping and insertion direction settings and the known obstacle position information. A series of processes such as acquisition of detailed position information by the work position detection sensor 106 and creation of a work program can be automatically performed. Further, detailed position data can be acquired using the workpiece position detection sensor 106 even in the teaching of a portion that is difficult for an operator to visually check, such as a narrow portion.

Even if the above-described method is used, for example, when a workpiece positioning error is large, there is a problem that the robot fails to hold the connector or to fit the connector during the reproduction operation. The second embodiment of the present invention addresses such a problem. The controller 102 has a work status determination unit 1025 (see FIG. 5) for determining the success or failure of the assembly work. When the work status determination unit 1025 determines that the operation has failed during the regeneration operation, the work position detection sensor 106 is used. Automatically re-measure the workpiece position and retry the work.
A specific example of connector fitting will be described. When the work situation determination unit 1025 determines that the connector fitting has failed, a command for moving the robot to the assembly fitting position C is issued from the command generation unit 1021. After moving to the assembly fitting position C, the position of the female connector 1051 is again measured by the work position detection sensor 106 arranged on or around the end effector 104, and the detailed position C ″ of the female connector 1051 is obtained. Re-import.
Judgment of the success / failure of the assembly work is performed in the work situation judgment unit 1025 depending on, for example, whether or not the end effector 104 has reached a commanded position in the insertion direction.
For example, in FIG. 6, the male connector 1052 interferes with the female connector 1051, and the connector fitting is not completed. In such a case, the robot coordinate system command position (dotted line in the figure) obtained by forward-converting the position command for each axis of the robot 101 and the feedback in the robot coordinate system obtained by forward-converting the position feedback value obtained from the encoder information of the motor. When the positions are compared, an error between the two (indicated by a double-ended arrow in FIG. 6) exceeds a preset threshold value, and it is determined that the operation has failed.
Further, a force sensor is provided between the end effector and the robot hand, and a time series pattern of force sensor information at the time of successful work is stored in advance in the teaching data storage unit 1023, so that a time series pattern at the time of reproduction operation is stored. By comparing with, you can also determine the success / failure of the work. The determination result of the success / failure of such assembly work may be displayed on the display of the teaching device 103 and presented to the operator.

  According to this method, the operation status determination unit 1025 monitors the execution status of the operation, and when the deviation between the position command and the actual position is large, the position of the robot is corrected and the operation is retried. It is possible to automatically perform from work failure judgment to retry.

When the position of an obstacle has changed from the time of teaching during playback operation, or when a new obstacle that did not exist at the time of teaching has been generated, it is not possible to respond by simply entering the position information of a known obstacle There is. The third embodiment of the present invention addresses such a problem.
During the reproduction operation, new obstacles are sequentially formed in the vicinity using the workpiece position detection sensor 106 disposed on or around the end effector 104 and the plurality of obstacle position detection sensors 107 disposed on the arm of the robot 101. Non-contact monitoring for occurrence of The workpiece position detection sensor 106 mainly monitors the advancing direction of the arm, and the obstacle position detection sensor 107 mainly monitors the periphery of the arm.

A case where a new obstacle 1084 is generated on the path from the waypoint B to the assembly fitting position C ′ will be described as an example with reference to FIG. Although it moves as usual from the connector acquisition position A ′ to the via point B, the workpiece position detection sensor 106 recognizes that there is an obstacle 1084 on the path while moving from the via point B to the assembly fitting position C ′. Is done.
For example, if the workpiece position detection sensor 106 is a one-dimensional laser sensor, the workpiece position detection sensor 106 detects the contour of the obstacle 1084 as the arm moves from before and after passing through the route point B.
Although the one-dimensional laser sensor can only acquire the distance data from the sensor to the obstacle, the position and orientation of the sensor fixed position on the robot 101 in the robot coordinate system can be calculated from the angle of each axis of the robot. And the contour data of the obstacle 1084 in the robot coordinate system can be obtained from the distance data of the one-dimensional laser sensor.
By extracting inflection points corresponding to the corners of the obstacle 1084 from the contour data, the size and the position of the center of gravity of the obstacle 1084 can be obtained.
The recognition result of the obstacle and information such as the position and size of the obstacle are sent to the posture calculation unit 1024.
In the posture calculation unit 1024, the work program along the new motion path (solid line in FIG. 7) is corrected in real time so as to avoid the obstacle 1084 from the original motion path (dashed line in FIG. 7). The robot can continue to operate while avoiding the obstacle 1084.
In addition, the method of correcting in real time the work program along the new motion path that avoids the obstacle 1084 from the information such as the position and size of the obstacle in the posture calculation unit 1024 takes into account the size of the end effector in advance. Then, a safety area (dotted line in FIG. 7) inflated by a predetermined distance from the outline of the obstacle is set, and when the obstacle 1084 is detected, the safety area is applied to the surrounding area and the operation path is set so as to pass the outside. change. Further, when the operation path changes sharply when avoiding the safety area, filter processing or the like is added so that the operation path is smoothly connected.

  The above describes the case where a new obstacle is detected by the workpiece position detection sensor 106. However, when the obstacle position detection sensor 107 determines that the elbow has approached the obstacle during movement, the path of the end effector is described. Without correcting, only the elbow angle may be corrected in the direction away from the obstacle. As the obstacle position detection sensor 107, an ultrasonic sensor, an area sensor, or the like can be used in addition to the one-dimensional laser sensor.

  According to the present invention, obstacles around the robot are monitored by the position detection sensor, so that even if the position of a known obstacle is changed or a new obstacle is generated during the reproduction operation, the obstacle is detected before contact. The operation path can be corrected in time, re-teaching is not required, damage to the robot, end effector, and workpiece can be prevented, and the yield can be improved.

  According to the present invention, in the teaching reproduction operation of an industrial robot for welding, painting, assembly, etc., the position roughly taught by the operator is automatically corrected by using the external sensor and the attitude calculation unit. It is possible to create an optimal work program. Also, during the regeneration operation, obstacle avoidance can be performed dynamically using the external sensor.

The block diagram of the robot system in 1st Example of this invention Detailed view of position teaching example in the first embodiment of the present invention Detailed view of the method of determining the posture of the end effector in the first embodiment of the present invention Detailed view of teaching correction example in the first embodiment of the present invention The block diagram of the robot system in 2nd Example of this invention Detailed view of an example of work status determination during regeneration operation in the second embodiment of the present invention Detailed view of a route correction example during regeneration operation in the third embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Robot 102 Controller 1021 Command generation part 1022 Servo control part 1023 Teaching data storage part 1024 Posture calculation part 1025 Work condition judgment part 103 Teaching apparatus 104 End effector 105 Work 1051 Female connector 1052 Male connector 106 Work position detection sensor 107 Obstacle Position detection sensors 1081, 1082, 1083, 1084 Obstacle 109 Case

Claims (9)

A robot having a plurality of joints and having an end effector attached to the tip, a teaching data storage unit for storing teaching data and a work program of the robot, and command generation for generating an operation command to the robot based on the work program A robot controller provided with a servo controller that drives a servo motor of each joint of the robot by the operation command, and a teaching device connected to the robot control device,
In the robot system that performs an operation of gripping the work placed at the first predetermined position by the end effector and fitting it to the second predetermined position,
The robot controller is
Temporarily taught workpiece gripping point and fitting point, each position of the via point between the workpiece gripping point and the fitting point,
The posture of the end effector at the workpiece gripping point and the fitting point;
A robot system, comprising: a posture calculation unit that generates a work program for performing fitting while avoiding the obstacle from positions of obstacles existing around the robot, and stores the program in the teaching data storage unit.   2. The robot according to claim 1, wherein the robot is an articulated robot having redundant degrees of freedom, and the posture calculation unit determines the posture of the end effector and the redundant degrees of freedom when generating the work program. Robot system.   The teaching data storage unit includes provisionally taught workpiece gripping points and fitting points, positions of via points between the workpiece gripping points and the fitting points, and the end effector at the workpiece gripping points and the fitting points. The robot system according to claim 1, wherein the posture and the position of an obstacle existing around the robot are stored as the teaching data.   The robot system according to claim 3, wherein the teaching data storage unit acquires the position of an obstacle existing around the robot from CAD data of an environment in which the robot operates. The robot includes a workpiece position detection sensor at a tip, and the posture calculation unit determines the temporary position based on the position of the workpiece arranged at the first predetermined position acquired by the workpiece position detection sensor when generating the work program. Correct the position of the workpiece gripping point
The robot system according to claim 1 or 2, wherein the provisionally taught fitting point position is corrected by the second predetermined position acquired by the workpiece position detection sensor. The posture calculation unit interpolates a plurality of points between the corrected work gripping point and the via point when generating the work program, and between the via point and the corrected fitting point,
The robot system according to claim 5, wherein postures of the end effector and the redundancy degree of freedom are determined for the plurality of interpolation points. The robot controller compares a command position obtained by forward-converting a position command to each axis of the robot with a feedback position obtained by forward-converting a position feedback value by an encoder of the servo motor, and a threshold value for which an error is set in advance. If it exceeds, it has a work status judgment unit that judges work failure,
When it is determined that the operation has failed in the fitting during the regeneration operation, the work position detection sensor detects the second predetermined position, and the fitting operation is performed again on the detected position. The robot system according to claim 5.   The robot system according to claim 7, wherein when the work situation determination unit determines that the work has failed, the robot system is presented to the worker via the teaching device. The robot includes an obstacle position detection sensor that measures the position of a surrounding obstacle on the arm,
2. The posture calculation unit detects an unknown obstacle in the vicinity of the robot by the obstacle position detection sensor during the reproduction operation of the work program, and dynamically corrects the work program. The robot system described.

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