Control device and control method

Abstract

Provided are a device and a method capable of operating an industrial machine without interfering with other equipment or the like in the interval between when an abnormality occurs and when a task is resumed. The control device is configured to control a plurality of industrial machines that perform a task cooperatively according to a predetermined operation program, and comprises: an abnormality detection unit that detects that an abnormality has occurred while performing the task; a stopping unit that, when the abnormality detection unit detects an abnormality, interrupts the execution of the operation program and performs a stopping process for stopping the plurality of industrial machines at the respective stop positions; a synchronization control unit that, before the operation program is resumed, performs a synchronization control for operating the plurality of industrial machines in reverse for a predetermined time or distance from the respective stop positions toward the respective positions / orientations at the time the abnormality occurred, while maintaining the relationship between the positions / orientations of the plurality of industrial machines in the stop process; and a program resumption unit that resumes the operation program after the synchronization control ends.

Description

Control device and control method

[0001] The present disclosure relates to a control device and a control method.

[0002] In production lines that use robots and machine tools to perform arc welding, laser processing, etc., the production line may temporarily stop due to an abnormality such as arc failure or laser failure during processing. In such cases, there is a certain time lag between the occurrence of the abnormality and the production line stopping, and since the robot or other device may coast during that time, a discrepancy may occur between the position of the robot or other device when the abnormality occurs and the position of the robot or other device when the production line stops.

[0003] If the robot's operation program is restarted and machining is resumed after the production line has stopped due to an abnormality, there is a risk that the section from the position where the abnormality occurred to the position where machining is resumed will remain unmachined. To avoid this, a technology has been proposed in which the robot is moved backward a specified distance from the stopped position before machining is resumed.

[0004] JP 01-177922 JP 62-079918 JP 06-047547 JP 06-091370

[0005] Although techniques for determining the distance to reverse a robot or the like have been proposed in the past, no specific control aspects for reversing a robot or the like have been considered. In particular, in cooperative operations in which multiple robots or machine tools are controlled in synchronization with each other, if each device is tried to reverse independently after a stop due to an abnormality occurs, there is a risk that each device will interfere with peripheral devices or the workpiece.

[0006] Therefore, there is a need for an apparatus and method that can operate industrial machinery without interfering with other equipment during the period from when an abnormality occurs until work is resumed.

[0007] One aspect of the present disclosure is at least one control device that controls a plurality of industrial machines that work together in accordance with a predetermined operation program, the control device having: an abnormality detection unit that detects the occurrence of an abnormality during the work; a stop processing unit that, when the abnormality detection unit detects an abnormality, suspends execution of the operation program and performs a stop processing that stops the plurality of industrial machines at their respective stop positions; a synchronization control unit that performs synchronous control to move the plurality of industrial machines backward from their respective stop positions by a predetermined distance or time, toward their respective position and posture when the abnormality occurred, while maintaining the relationship between the position and posture of the plurality of industrial machines during the stop processing, before resuming the operation program; and a program resumption unit that resumes the operation program after the synchronous control is completed.

[0008] Another aspect of the present disclosure is a control method for controlling a plurality of industrial machines that work in cooperation with each other in accordance with a predetermined operation program, the control method including: detecting that an abnormality has occurred during the work; when the abnormality is detected, suspending execution of the operation program and performing a stop process to stop the plurality of industrial machines at their respective stop positions; before resuming the operation program, performing synchronous control to move the plurality of industrial machines backward from their respective stop positions by a predetermined distance or time toward their respective position and posture when the abnormality occurred, while maintaining the relationship between their position and posture in the stop process; and resuming the operation program after the synchronous control is completed.

[0009] 7B is a schematic configuration diagram of a system including a control device according to an embodiment. FIG. 9 is a diagram illustrating an example of an operation in which a robot stops when an abnormality occurs and moves backward along its path. FIG. 9B is a diagram illustrating an example of an operation in which a robot stops and retreats when an abnormality occurs and moves backward along its path. FIG. 9C is a flowchart illustrating an example of processing in a control device. FIG. 9D is a diagram illustrating an example of storing position and posture information of a robot at time-based intervals. FIG. 9E is a diagram illustrating an example of storing position and posture information of a robot at time intervals larger than that of FIG. 5A. FIG. 9F is a diagram illustrating an example of storing position and posture information of a robot at time-based intervals. FIG. 9G is a diagram illustrating an example of storing position and posture information of a robot at distance-based intervals. FIG. 9H is a schematic diagram of a welding torch and a workpiece. FIG. 9H is a diagram illustrating a state in which the welding torch and the workpiece are moved relatively to each other in opposite directions. FIG. 9H is a diagram illustrating a state in which the welding torch and the workpiece are moved backward from the state of FIG. 7B. FIG. 9H is a diagram illustrating a state in which the welding torch and the workpiece are moved relatively to each other in the same direction. FIG. 9H is a diagram illustrating a state in which the welding torch and the workpiece are moved backward from the state of FIG. 8B. FIG. 9H is a diagram illustrating an example of densely setting interpolation points of a motion path. FIG. 9H is a diagram illustrating an example of acquiring information on some of the interpolation points of FIG. 9A.

[0010] 1 is a schematic diagram of a system including a control device according to an embodiment. The system 2 has a plurality of industrial machines that work together in accordance with a predetermined operation program. In this embodiment, welding work is performed using an industrial robot 4, such as a vertical articulated robot, and a positioner 6 as the industrial machines.

[0011] The robot 4 includes a movable part (e.g., a robot arm 8) and a welding torch 10 attached to the tip of the robot arm 8, and is configured to be able to perform welding work on an object to be welded (workpiece) 12 held by a positioner 6. However, this is just one example, and for example, another robot capable of holding the workpiece 12 may be used instead of the positioner 6. Furthermore, the predetermined work is not limited to welding, and for example, laser processing, assembly work, transport work, etc. using multiple industrial machines can also be performed.

[0012] The system 2 includes a robot control device 14 that is equipped with a processor, a memory, etc. and controls the robot 4. Using a teaching device 16 such as a teaching operation panel that is communicatively connected to the robot control device 14 via wire or wirelessly, an operator can input various information to the robot control device 14, receive information from the robot control device 14, and display the information on a display or the like of the teaching device 16.

[0013] The system 2 includes a welding power source 18 that is communicatively connected to the robot controller 14 via wire or wireless communication and that can supply a welding current, etc., to the welding torch 10, and a controller 20 that includes a processor, memory, etc. and controls the positioner 6. However, the robot controller 14 and the controller 20 may be separate devices as shown in the illustrated example, or may be configured as a substantially integrated device. Furthermore, the system 2 may include an external storage device 22 communicatively connected to the robot controller 14 via wire or wireless communication as a means for storing data and information, which will be described later. In this embodiment, the welding power source 18 corresponds to the anomaly detection unit, the processors of one or both of the robot controller 14 and the controller 20 correspond to the stop processing unit, the save processing unit, the synchronization control unit, and the program restart unit, and an internal storage device, such as a memory built into one or both of the robot controller 14 and the controller 20, or an external storage device corresponds to the storage unit.

[0014] 2 and 3, the operation and processing of system 2 will be described below. First, in step S1, when a predetermined operation program is executed in robot control device 14 or the like, robot control device 14 and control device 20 respectively control robot 4 and positioner 6, and welding work is performed while torch 10 moves relatively along the surface of workpiece 12, as shown in part A of Fig. 2. Specifically, control is performed such that positioner 6 rotates workpiece 12 as shown by arrow 24, while robot 4 moves torch 10 along arrow 26.

[0015] In the next step S2, it is detected whether an abnormality has occurred in the welding operation being performed, and if an abnormality is detected, the execution of the operation program is interrupted (step S3). For example, if the current or voltage value supplied to the torch 10 exceeds the normal range, the welding power source 18 functions as a detector that detects this and can notify the robot control device 14 of the occurrence of the abnormality along with the time of the occurrence. Here, it is assumed that a welding abnormality has occurred at position 28, as shown in part B of Figure 2.

[0016] When the operation program is interrupted, the robot control device 14 and the control device 20 execute stop processing for the robot 4 and the positioner 6, respectively (step S4). This stop processing is performed to enable the torch 10 to stop smoothly without interfering with the positioner 6 or the workpiece 12, because even if an abnormality occurs in the torch 10 at position 28, the torch 10 cannot immediately stop at position 28 due to its own inertia or the coasting of the robot arm 8. Here, as shown in part B of Figure 2, it is assumed that the torch 10 continues to move over the workpiece 12 along path 30 and stops at position 32, even after the abnormality occurs. It is also assumed that the workpiece 12 changes from the tilted state shown in part A of Figure 2 to an upright state shown in part B and stops as a result of the stop processing of the positioner 6.

[0017] The next step is to eliminate the cause of the welding abnormality and resume the operation program, which involves returning one or both of the positions and attitudes (hereinafter also referred to as position and attitude) of the torch 10 and workpiece 12 from the state shown in part B of Fig. 2 to the state shown in part A. If the robot 4 and positioner 6 perform return operations independently of each other, as shown in part C of Fig. 2, the workpiece 12 will rotate along arrow 34, while the torch 10 will attempt to move linearly from position 32 to position 28 along arrow 36. This will cause the torch 10 to interfere with the workpiece 12, making it difficult to resume the operation program.

[0018] Therefore, in this embodiment, before resuming the operation program, synchronous control is performed to move the robot 4 and the positioner 6 a predetermined distance from their respective stopping positions, while maintaining the relationship between the position and posture of the robot 4 and the positioner 6 (in this embodiment, the torch 10 and the workpiece 12) in the above-mentioned stopping process, toward their respective position and posture when the abnormality occurred (step S5).

[0019] A specific example of information required for the processing of step S5 is data obtained by storing (simultaneously) sets of the positions and orientations of the robot 4 (representative points such as the tool tip point of the robot 4) and the positioner 6 (the workpiece 12 held by the positioner 6) during machining at predetermined interpolation periods during execution of the operation program. At this time, each set may be stored in association with its respective time of occurrence. This data is saved in the memory of the robot control device 14, the memory of the control device 20, or the external storage device 22 until the robot 4 and the positioner 6 are stopped by the stop processing in step S4. Generally, the external storage device 22 has a larger storage capacity than the internal memory of the robot control device 14 or the control device 20, so using the external storage device 22 makes it possible to store data for a longer period of time.

[0020] In the present disclosure, "as a set (storage)" means that the positions and postures of the robot and the positioner are stored simultaneously, as described above, and thus data that combines the positions and postures of the robot and the positioner at the same time is obtained. In this case, the data may be stored in a memory or the like in association with the time at which they were stored.

[0021] In the synchronization control of step S5, the robot 4 and positioner 6 are simultaneously replayed from the state after the stop processing using the above-mentioned data, with the data stored as a set, in the reverse direction of the storage order (chronological order) for a predetermined distance or time. This predetermined distance or time can be appropriately specified or set by, for example, an operator, but it is preferable to set it so that the synchronization control moves the robot 4 or positioner 6 back to the position at which the abnormality occurred or some distance (for example, 1 to 3 millimeters) before that position.

[0022] Due to the synchronization control in step S5, when the robot 4 and the positioner 6 move back to the position where the abnormality occurred, the robot 4 and the positioner 6 do not operate independently, but rather can move back while maintaining the same positional and pose relationships as during the stop processing. Therefore, as shown in part D of FIG. 2 , the torch 10 moves over the workpiece 12 along a path 38 that is the same shape as the path 30 but in the opposite direction, and can return to the position 28 where the abnormality occurred without interfering with the workpiece 12. In this manner, in this embodiment, the robot 4 and the positioner 6 simultaneously perform the reverse operations from those performed during the stop processing using the data set used during the stop processing, so the robot 4 and the positioner 6 can return to the state where the abnormality occurred without interfering with other equipment, the workpiece, etc. Note that if a malfunction occurs during the stop processing, such as interference between the robot 4 and other equipment, the data set related to that malfunction can be prevented from being used during synchronization control.

[0023] In the next step S6, the operation program interrupted in step S3 is resumed, and the predetermined work such as welding is continued. If the execution of the operation program is completed without detecting any abnormality, the series of processes ends (step S7).

[0024] Figure 4 shows an example of another operation that can be performed by system 2. In the example of Figure 4, as shown in part E, it is assumed that an abnormality occurs at position 42 while torch 10 is welding an object (not shown) along arc-shaped path 40. Next, a stop process is performed to move torch 10 along path 44 and stop at stop position 46, and then a retract process is performed to move to retract position 50 along retract path 48. At retract position 50, wire cutting is performed using an appropriate cutting means 52. That is, in the example of Figure 4, after stopping due to the abnormality, the robot (torch 10) is again moved to a predetermined retract position for wire cutting.

[0025] 4, if the torch 10 is moved along a simple linear path 54 to the position 42 at the time of the abnormality occurrence, there is a risk of interference with other equipment, not shown. Also, when the torch 10 is returned to the position 46 after the stop processing, there is a risk of interference with other equipment, if the torch 10 is moved along a simple linear path 56. Furthermore, when the robot returns from the evacuation position to the position at which the abnormality occurred, it is difficult to predict the attitude of the robot when it returns.

[0026] Therefore, as shown in part G of Figure 4, synchronous control is performed to first return the torch 10 along the retraction path 48 to the stop position 46, and then move it backward a predetermined distance or time toward the position 42 where the abnormality occurred. As with the example of Figure 2, this synchronous control can be performed using data obtained by storing (simultaneously) a set of data on the positions and orientations of the robot 4 and positioner 6 during processing at predetermined interpolation intervals during program execution, stop processing execution, and retraction operation execution. In this way, even if a retraction operation is performed again after the robot has stopped due to an abnormality, the retraction operation is first played back in the reverse direction, and then the operation during the stop processing is played back in the reverse direction, thereby allowing the torch 10 to be returned to the position where the abnormality occurred without interference.

[0027] 5A and 5B show examples of specifying the storage of position and orientation information of an industrial machine such as a robot at predetermined time intervals. In the example of Fig. 5A, when the robot moves along an arc-shaped path 60 in the direction of arrow 61 at a speed of 500 millimeters per minute to perform work such as welding, one interpolation is set to 1 millisecond, and information on the position and orientation of the robot at positions 66a corresponding to each interpolation point is stored. On the other hand, in the example of Fig. 5B, when the robot moves along path 60 in the direction of arrow 61 at a speed of 1000 millimeters per minute to perform work such as welding, one interpolation is set to 1 millisecond, and information on the position and orientation of the robot at positions 66b corresponding to each interpolation point is stored.

[0028] In the example of Figure 5A, if an abnormality occurs at position 62a, stopping processing is executed from position 62a, and the robot stops at position 64a after four interpolations. On the other hand, in the example of Figure 5B, if an abnormality occurs at position 62b, stopping processing is executed from position 62b, and the robot stops at position 64b after four interpolations. When the robot's operating speed is different in this way, even if the robot's stopping processing is executed using the same number of interpolations, the distance traveled from the occurrence of the abnormality to the point of stopping will be different. Therefore, as shown by arrows 68a and 68b, the length of the path that the robot must reverse from the stopping position to the position where the abnormality occurred will also be different.

[0029] However, by storing position information based on a time standard such as 1 millisecond, in both the cases of Figures 5A and 5B, if the number of interpolations for synchronous control from the stopped position is specified as four interpolations, the robot can be automatically returned to the position where the abnormality occurred. In other words, in the examples of Figures 5A and 5B, if the reversing movement is specified as a time interval (number of interpolations), the reversing distance becomes variable depending on the movement speed, and the distance is automatically determined to an appropriate value. Note that if the robot's movement speed is quite high, a long time period for storing position and orientation information may result in an insufficient amount of information to be stored, so a shorter time period can be specified.

[0030] 6A and 6B show examples of specifying the storage of position and orientation information of an industrial machine such as a robot at predetermined time intervals and distance intervals, respectively. In the example of FIG. 6A , when a robot moves along an arc-shaped path 70 in the direction of arrow 71 at a speed of 600 millimeters per minute to perform work such as welding, one interpolation is set to 1 millisecond, for example, and the position and orientation information of the robot at position 72 a corresponding to each interpolation point is stored. In this case, information is stored at 0.01 millimeter intervals along the path 70, resulting in an excessive amount of data for use in subsequent synchronization control, etc. When storing position information based on time in this way, depending on the value of the interpolation period, position and orientation information may be stored at intervals shorter than necessary, unnecessarily increasing the amount of data and placing a strain on memory, etc.

[0031] 6B, when performing the same operation as in Fig. 6A, it is preferable to store information based on distance, such as by storing position and orientation information every time the torch 10 moves 1 mm. In this way, among the positions corresponding to the multiple interpolation points, position and orientation information is stored only at position 72b1 indicated by a black circle, and information is not stored at other positions 72b2 indicated by white circles, which reduces the amount of data stored and saves on the data capacity of memory, etc.

[0032] 7A to 7C show an application example of storing position and orientation information at distance-based intervals. Here, consider a case where welding is performed on a workpiece 12 having an arc-shaped portion using a welding torch 10, as shown in FIG.

[0033] 7B , during welding, the torch 10 and the workpiece 12 move in generally opposite directions. Specifically, the torch 10 moves along arrow 74, and the workpiece 12 moves (rotates) along arrow 75, which is generally the opposite direction to arrow 74. In this example, it is assumed that an abnormality is detected when the torch 10 and the workpiece 12 each rotate 25°, and that the torch 10 and the workpiece 12 are subsequently stopped after moving an additional 5° due to a stop process.

[0034] In this case, a weld line 76 spanning a range of 60° will be formed on the workpiece 12. Therefore, as shown in Figure 7C, the torch 10 should be moved backward by 10° along the weld line 76 relative to the workpiece 12 by synchronous control that moves the torch 10 and the workpiece 12 backward along arrows 78 and 80, respectively. However, if the backward movement distance is specified as an absolute distance, specifying "10°," for example, will result in the torch 10 and the workpiece 12 each moving backward by 10°, resulting in the distance (angle α) by which the torch 10 moves backward relative to the workpiece 12 being 20°.

[0035] Therefore, it is preferable that the distance interval specified in the synchronization control be specified based on the relative distance between the torch 10 and the workpiece 12, rather than the absolute distance. If the distance is relative, as in this embodiment, when both the torch 10 and the workpiece 12 are operating, control is performed such that each moves by 5°. Therefore, regardless of the speed of the torch 10 and the workpiece 12, the moving distance of the torch relative to the workpiece is constant, and consistent processing quality is obtained.

[0036] 8A to 8C show another application example of storing position and orientation information at distance-based intervals. Here, consider a case where welding is performed on a workpiece 12 having an arc-shaped portion using a welding torch 10, as shown in FIG.

[0037] 8B , during welding, both the torch 10 and the workpiece 12 move in approximately the same direction. Specifically, the torch 10 moves along arrow 82, and the workpiece 12 moves (rotates) along arrow 84, which is approximately the same direction as arrow 82. Here, it is assumed that an abnormality is detected when the torch 10 and the workpiece 12 rotate by 29° and 30°, respectively. In this case, the torch 10 and the workpiece 12 each move a certain distance due to the subsequent stop processing, but because they are moving in the same direction, their relative position and orientation remain approximately the same as when the abnormality occurred.

[0038] In this case, a weld line 86 spanning a range of 1° will be formed on the workpiece 12, and synchronous control should be performed to move the torch 10 backward a predetermined distance relative to the workpiece 12 along arrow 90, as shown in FIG. 8C . However, if the backward movement distance is specified as a relative distance, in this embodiment, even though the torch 10 and workpiece 12 move 29° and 30°, respectively, the relative distance between them only changes by 1°. Therefore, even if it is specified that "position and orientation information is stored every time the relative distance changes by 1°," the information is not stored until the workpiece 12 moves 30°. Therefore, the amount of data stored is small compared to the absolute movement distance of the workpiece 12. As a result, synchronous control results in the torch 10 moving linearly between positions 88 corresponding to two interpolation points, which may result in problems such as interference with the workpiece 12.

[0039] Therefore, it is preferable to specify the distance intervals specified in synchronization control based on the absolute distances between the torch 10 and the workpiece 12, rather than the relative distances. If the absolute distances are used, even if the relative distance changes by only 1° as in this embodiment, the position and orientation information is stored as multiple sets corresponding to the absolute distances, making it possible to store a sufficient amount of data to perform appropriate synchronization control without interference.

[0040] 9A is a diagram showing an example in which positions 96a corresponding to a plurality of interpolation points are displayed superimposed on a motion path 94 when a robot or the like moves in the direction of an arrow 95 on the path 94, which includes rounded corners. In this case, if information on the position and orientation of the robot or the like at each of the positions 96a is stored, excessive data may be stored depending on the interpolation cycle, which may cause a strain on the storage capacity of a memory or the like.

[0041] 9B, when storing position and orientation information, it is possible to store the position and orientation information of the robot, etc. only at positions corresponding to some of the interpolation points. In this example, the section between positions 96b1 and 96b2 is a straight-line path 98, the section between positions 96b2 and 96b3 is a curved path 100 with a radius R, and the section between positions 96b3 and 96b4 is a straight-line path 102. Therefore, by setting and storing the position information of these four points and the interpolation type of each path (here, straight-line movement or curved movement with a radius R) in advance, the position and orientation of the robot, etc. at other interpolation points can be found by calculation.

[0042] When storing position and posture information in this way, by storing information sufficient to perform synchronous control to reverse the movement path while maintaining the posture during processing, such as the teaching position and movement type, at the required timing (here, the timing of transition from linear movement to curved movement (or vice versa)), the amount of data stored can be significantly reduced compared to when position information is stored for each interpolation point, and suitable synchronous control can be performed.

[0043] The position and orientation data of the industrial machine in the above-described embodiments can be obtained from detection values ​​based on the output of encoders provided on each axis of the robot or positioner, for example. Alternatively, the position and orientation data can be obtained based on command values ​​sent to the robot or positioner by a robot control device or a positioner control device.

[0044] According to an embodiment of the present disclosure, position and orientation data for multiple work machines during forward operation from the time an abnormality occurs until stoppage processing is stored as a set, and this data is used to perform reverse operation that reverses the route, making it possible to easily perform reverse operation while maintaining the position and orientation relationships between the machines during forward operation, i.e., reverse playback of forward operation. This makes it possible to perform an ideal return operation that does not cause interference between machines or between machines and other equipment, etc.

[0045] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0046] The following additional notes are provided regarding the above-described embodiment and modifications.

[0047] (Supplementary Note 1) A control device that controls at least one plurality of industrial machines that work in cooperation with each other in accordance with a predetermined operation program, the control device having: an abnormality detection unit that detects the occurrence of an abnormality during the work; a stop processing unit that, when the abnormality detection unit detects an abnormality, suspends execution of the operation program and performs stop processing to stop the plurality of industrial machines at their respective stop positions; a synchronization control unit that performs synchronization control to move the plurality of industrial machines backward from their respective stop positions by a predetermined distance or time, toward their respective position and posture when the abnormality occurred, while maintaining the relationship between their position and posture in the stop processing, before resuming the operation program; and a program resumption unit that resumes the operation program after the synchronization control has ended.

[0048] (Supplementary Note 2) The control device according to Supplementary Note 1, further comprising an evacuation processing unit that performs evacuation processing to move at least one of the plurality of industrial machines from the stop position to a predetermined evacuation position, wherein the synchronization control unit performs synchronous control to move the industrial machines from the evacuation position to the stop position in reverse toward the respective positions and postures of the stop position while maintaining the relationship between the positions and postures of the plurality of industrial machines in the evacuation processing.

[0049] (Supplementary Note 3) The control device according to Supplementary Note 1 or 2, further comprising a memory unit that stores a set of information on the positions and postures of the plurality of industrial machines at the same time while the operation program is being executed, and the synchronization control unit performs the synchronization control based on the information stored in the memory unit.

[0050] (Supplementary Note 4) The control device according to Supplementary Note 3, wherein the storage unit is an internal storage device built into the control device or an external storage device communicably connected to the control device.

[0051] (Supplementary Note 5) The control device according to Supplementary Note 3, wherein the storage unit stores the position and orientation information at time-based intervals.

[0052] (Supplementary Note 6) The control device according to Supplementary Note 3, wherein the storage unit stores the position and orientation information at distance-based intervals.

[0053] (Supplementary Note 7) The control device according to Supplementary Note 6, wherein the storage unit stores the position and orientation information at intervals based on a relative distance between each position of the plurality of industrial machines.

[0054] (Supplementary Note 8) The control device according to Supplementary Note 6, wherein the storage unit stores the position and orientation information at intervals based on an absolute distance between positions of the plurality of industrial machines.

[0055] (Supplementary Note 9) The control device according to Supplementary Note 3, wherein the storage unit stores the position and orientation information only at positions corresponding to some of a plurality of interpolation points.

[0056] (Supplementary Note 10) A control method for controlling a plurality of industrial machines that work in cooperation with each other in accordance with a predetermined operation program, the control method including: detecting that an abnormality has occurred during the work; if the abnormality is detected, interrupting execution of the operation program and performing a stop process to stop the plurality of industrial machines at their respective stop positions; before resuming the operation program, performing synchronous control to move the plurality of industrial machines backward from their respective stop positions by a predetermined distance or time toward their respective position and posture when the abnormality occurred, while maintaining the relationship between their position and posture in the stop process; and resuming the operation program after the synchronous control has ended.

[0057] (Supplementary Note 11) The control method according to Supplementary Note 10, further comprising storing a set of information on the positions and postures of the plurality of industrial machines at the same time while the operation program is being executed, and the synchronization control is performed based on the stored information.

[0058] 2 Robot system 4 Robot 6 Positioner 8 Robot arm 10 Welding torch 12 Workpiece 14 Robot control device 16 Teaching operation panel 18 Welding power source 20 Control device 22 External storage device

Claims

1. At least one control device that controls a plurality of industrial machines that work in cooperation with each other according to a predetermined operation program, comprising: an abnormality detection unit that detects the occurrence of an abnormality during the operation; a stop processing unit that, when the abnormality detection unit detects an abnormality, interrupts execution of the operation program and performs a stop processing to stop the plurality of industrial machines at their respective stop positions; a synchronization control unit that performs synchronization control to move the plurality of industrial machines backwards toward their respective position and posture when the abnormality occurred a predetermined distance or time from their respective stop positions while maintaining the relationship between the position and posture of the plurality of industrial machines in the stop processing before resuming the operation program; and a program resumption unit that resumes the operation program after the synchronization control is terminated.

2. The control device according to claim 1, further comprising an evacuation processing unit that performs an evacuation process to move at least one of the plurality of industrial machines from the stop position to a predetermined evacuation position, and the synchronization control unit performs synchronous control to move the industrial machines from the evacuation position to the stop position in reverse toward the respective positions and postures of the stop positions while maintaining the relationship between the positions and postures of the plurality of industrial machines in the evacuation process.

3. A control device as described in claim 1 or 2, further comprising a memory unit that stores a set of information on the positions and postures of the multiple industrial machines at the same time while the operating program is being executed, and the synchronization control unit performs the synchronization control based on the information stored in the memory unit.

4. The control device according to claim 3, wherein the memory unit is an internal memory device built into the control device, or an external memory device communicatively connected to the control device.

5. The control device according to claim 3, wherein the memory unit stores the position and orientation information at time-based intervals.

6. The control device according to claim 3, wherein the memory unit stores the position and orientation information at distance-based intervals.

7. The control device according to claim 6, wherein the memory unit stores the position and orientation information at intervals based on a relative distance between each of the positions of the plurality of industrial machines.

8. The control device according to claim 6, wherein the memory unit stores the position and orientation information at intervals based on an absolute distance between each of the positions of the plurality of industrial machines.

9. The control device according to claim 3, wherein the storage unit stores the position and orientation information only at positions corresponding to a portion of a plurality of interpolation points.

10. A control method for controlling a plurality of industrial machines which work in cooperation with each other according to a predetermined operation program, comprising: detecting the occurrence of an abnormality during the work; when the abnormality is detected, interrupting the execution of the operation program and performing a stop process to stop the plurality of industrial machines at their respective stop positions; before resuming the operation program, performing synchronous control to move the plurality of industrial machines backwards a predetermined distance or time from their respective stop positions toward their respective position and posture when the abnormality occurred, while maintaining the relationship between the position and posture of the plurality of industrial machines in the stop process; and resuming the operation program after the synchronous control is completed.

11. The control method according to claim 10, further comprising storing a set of information on the positions and attitudes of the multiple industrial machines at the same time while the operating program is being executed, and the synchronization control is performed based on the stored information.

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