Control device and industrial machine system

Abstract

A control device (10), which causes an industrial machine (1) comprising at least one joint to execute a task, comprises at least one memory (30) and at least one processor (40), wherein: the memory (30) stores a load limit value for each joint and a change value for increasing the load limit values; and, in accordance with a control command for causing the industrial machine (1) to execute the task or a parameter included in the control command, the processor (40) can change the load limit value of the at least one joint on the basis of the change value.

Description

Control devices and industrial machinery systems

[0001] The present disclosure relates to a control device and a system for an industrial machine.

[0002] It is known that the threshold used in the contact detection function that stops the operation of a robot when the robot comes into contact with a person or the like is changed depending on the content of the operation performed by the robot (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2021-191594

[0004] On the other hand, the threshold value used for the emergency stop function, which stops the robot's operation to protect the robot when an excessive load is applied to the robot, is determined based on the robot's strength limit. Furthermore, this threshold value is generally estimated to be on the safe side in order to reliably prevent the robot from being subjected to a load exceeding its strength limit, which can result in excessive restrictions on the robot's operation.

[0005] Therefore, it is desirable to minimize restrictions on the robot's motion while preventing the robot from being subjected to loads that exceed its strength limit.

[0006] One aspect of the present disclosure is a control device that causes an industrial machine having at least one joint to perform a task, the control device comprising at least one memory and at least one processor, wherein the memory stores a load limit value of each of the joints and a modification value for increasing the load limit value, and the processor is capable of modifying the load limit value of at least one of the joints based on the modification value in accordance with a control command for causing the industrial machine to perform the task or a parameter included in the control command.

[0007] 1 is a side view showing a robot system according to a first embodiment of the present disclosure. FIG. 8 is a block diagram showing the configuration of a control device according to the first embodiment of the present disclosure. FIG. 9 is a graph showing an example of a load acting on the wrist tip when the robot system shown in FIG. 1 performs a screw tightening operation. FIG. 10 is a flowchart explaining the screw tightening operation of the robot system shown in FIG. 1. FIG. 11 is a diagram explaining the screw tightening operation of the robot system shown in FIG. 1. FIG. 12 is a diagram explaining the screw tightening operation of the robot system shown in FIG. 1. FIG. 13 is a block diagram showing the configuration of a control device according to a second embodiment of the present disclosure. FIG. 8 is an example of the display content of a display device connected to the control device shown in FIG.

[0008] A control device 10 and a robot system (industrial machinery system) 100 according to a first embodiment of the present disclosure will be described below with reference to the drawings. First, as shown in FIG. 1 , the robot system 100 according to this embodiment includes a robot (industrial machinery) 1, a tool T attached to the tip of the wrist of the robot 1, and a control device 10 that controls the robot 1 and the tool T.

[0009] The robot 1 is, for example, a six-axis articulated robot, and includes a base 2 installed on a floor F, and a rotating body 3 supported rotatably relative to the base 2 about a vertical first axis J1. The robot 1 also includes a first arm 4 supported rotatably relative to the rotating body 3 about a horizontal second axis J2, and a second arm 5 supported rotatably relative to the tip of the first arm 4 about a horizontal third axis J3. The robot 1 also includes a three-axis wrist unit 6 supported at the tip of the second arm 5.

[0010] The wrist unit 6 includes a first wrist element 6a supported rotatably relative to the second arm 5 about a fourth axis J4 extending along a plane perpendicular to the third axis J3. The wrist unit 6 also includes a second wrist element 6b supported rotatably relative to the first wrist element 6a about a fifth axis J5 perpendicular to the fourth axis J4. The wrist unit 6 also includes a third wrist element 6c supported rotatably relative to the second wrist element 6b about a sixth axis J6 perpendicular to the fifth axis J5 and intersecting the fourth axis J4. In other words, the robot 1 includes six joints A1 to A6.

[0011] Joint A1 is a rotary joint that rotates the rotating body 3 about the first axis J1 relative to the base 2 by means of a motor M1, and joint A2 is a rotary joint that rotates the first arm 4 about the second axis J2 relative to the rotating body 3 by means of a motor M2. Joint A3 is a rotary joint that rotates the first arm 4 and the second arm 5 relatively about the third axis J3 by means of a motor M3.

[0012] Joint A4 is a rotary joint that rotates the second arm 5 and the first wrist element 6a relatively about the fourth axis J4 by means of a motor M4. Joint A5 is a rotary joint that rotates the first wrist element 6a and the second wrist element 6b relatively about the fifth axis J5 by means of a motor M5. Joint A6 is a rotary joint that rotates the second wrist element 6b and the third wrist element 6c relatively about the sixth axis J6 by means of a motor M6.

[0013] The joints A1 to A6 are equipped with reducers (not shown) that reduce the rotation speed of the motors M1 to M6, and sensors S1 to S6. The sensors S1 to S6 are torque sensors that detect torques acting on the joints A1 to A6 around the axes J1 to J6, respectively, and send the detected torques to a control device 10, which will be described later.

[0014] The tool T is, for example, a nut runner used for screw tightening, a grinding stone used for polishing, or a grinder used for deburring, as shown in Fig. 1. The tool T is attached to the tip of the third wrist element 6c with a sensor S6 interposed therebetween.

[0015] 2, the control device 10 according to this embodiment includes an input device (display device) 20, at least one memory 30 such as a ROM or RAM, and at least one processor 40 such as a CPU. The input device 20 is, for example, a control panel, and includes operation buttons for receiving input of operation commands for the robot 1 from the operator, and a monitor for displaying information indicating the status of the robot 1, etc.

[0016] The memory 30 stores an operation program for operating the robot 1 and a safety shutdown program for protecting the robot 1. Also, as shown in FIG. 3 , the memory 30 stores a load limit value L1, which is set for each strength limit value LS of the joints A1 to A6 while taking into account a predetermined safety factor, and an adjustment value related to the amount by which each load limit value L1 is increased. In this case, each strength limit value LS is determined by the load-bearing capacity of the components that make up each joint A1 to A6, such as the motors M1 to M6, reducers, bearings (not shown), and the like. The adjustment value is, for example, an increase amount or rate when each load limit value L1 is increased within a range that does not exceed the corresponding strength limit value LS.

[0017] The operation program is, for example, a group of control commands for operating the robot 1 and the tool T. Specifically, the operation program includes control commands for rotating the motors M1 to M6 to sequentially change the posture of the robot 1 and position the tool T at a predetermined position. The operation program also includes control commands for operating the tool T at that position to tighten a screw with a predetermined tightening torque (parameter, target torque). Furthermore, the operation program may include control commands for a contact detection function that stops or slows down the operation of the robot 1 when the robot 1 or the tool T comes into contact with an external object, a person, or a work target.

[0018] The safety stop program is a group of control commands that stops the operation of the robot 1 to protect the robot 1, for example, when an excessive load acts on any of the joints A1 to A6 of the robot 1 during operation. Specifically, the safety stop program realizes a safety stop function that brings the operation of the robot 1 to an emergency stop when the detection values ​​of the sensors S1 to S6 exceed the corresponding load limit values ​​L1. The safety stop program in this embodiment also includes commands to increase the load limit values ​​L1 of the joints A1 to A6 based on the change values ​​stored in the memory 30, in accordance with the control commands of the operation program executed by the robot 1.

[0019] The processor 40 reads out the operation program and the safety stop program stored in the memory 30, and transmits control signals based on the control commands contained in both programs to the motors M1 to M6 of the robot 1. That is, the processor 40 executes the safety stop program at the same time as executing the operation program. This allows the processor 40 to stop the operation of the robot 1 when a load exceeding the load limit value L1 acts on any of the joints A1 to A6 of the robot 1 operating according to the operation program.

[0020] The operation of the control device 10 according to this embodiment configured as described above will be described below. A control method for causing the robot system 100 to which the control device 10 is applied to execute an operation mode for screw tightening work will be described below with reference to the flowchart of FIG.

[0021] First, the worker operates the input device 20 to input an execution command for the operation mode of a screw tightening operation to the robot 1. In response, the processor 40 reads out the operation program and the safety stop program stored in the memory 30 and executes both programs (step s1). Then, in conjunction with the execution of the safety stop program, the processor 40 increases each of the load limit values ​​L1 set for the joints A1 to A6 of the robot 1 based on the change value stored in the memory 30 (step s2).

[0022] Next, the processor 40, in accordance with the operation program, supplies drive currents to the motors M1 to M6 of the robot 1. This causes the output shafts of the motors M1 to M6 to rotate, changing the posture of the robot 1, and as shown in Figure 5, the screw B, which has been attached to the tool T in advance, is brought closer to the screw hole H provided in the workpiece.

[0023] The processor 40 then slightly changes the posture of the robot 1 in accordance with the operation program, and adjusts the position and posture of the tool T so that the central axis of the screw B coincides with the central axis of the screw hole H, as shown in Fig. 6. Specifically, the processor 40 lightly contacts the tip of the screw B with the inner circumferential surface of the screw hole H, and adjusts the tool T to the target position and posture based on the detection values ​​of the sensors S1 to S6 acquired at that time. That is, as shown at time t1 in Fig. 3, a relatively small load acts on joint A6, which is the joint at the tip of the wrist of the robot 1, as the screw B comes into contact with the screw hole H. The same applies to the other joints A1 to A5.

[0024] During this operation, the processor 40 compares the detected values ​​of the sensors S1 to S6, i.e., the loads acting on the joints A1 to A6, with the corresponding increased load limit values ​​L1 (step s3). In the example shown in Fig. 3, the loads acting on the joints A1 to A6 are all sufficiently smaller than the corresponding load limit values ​​L1, so the operation of the robot 1 is not stopped. Furthermore, at this point, the operation program has not ended, and the screw tightening operation has not been completed, so the operation program continues (step s4).

[0025] 7 , the processor 40 operates the robot 1 in accordance with the operation program to press the screw B into the screw hole H, while operating the tool T. As a result, the screw B is fastened into the screw hole H with a predetermined tightening torque.

[0026] Then, for this operation as well, the processor 40 compares the loads acting on the joints A1 to A6 with the corresponding increased load limit values ​​L1 (step s3). In the example shown at time t2 in Figure 3, when the screw B is completely tightened into the screw hole H, the greatest load is acting on the joint A6, but the increased load limit value L1 for the joint A6 has not yet been reached. The same is true for the other joints A1 to A5. Therefore, the operation of the robot 1 is not stopped.

[0027] Thereafter, the processor 40 operates the robot 1 in accordance with the operation program to separate the tool T from the workpiece having the screw hole H. This completes the operation of fastening one screw. Furthermore, upon completion of the operation program, i.e., the operation mode for fastening the screw, the processor 40 returns the increased load limit values ​​L1 of the joints A1 to A6 to their original values ​​(step s5).

[0028] On the other hand, if a load exceeding the increased load limit value L1 acts on at least one of the joints A1 to A6 during any of the operations in the series of screw tightening tasks, the processor 40 stops the operation of the robot 1 (step s6). This makes it possible to prevent the robot 1 from being subjected to a load exceeding the strength limit value LS of the joints A1 to A6.

[0029] In this way, when the robot 1 executes an operation mode in which a large load is expected to be applied to the joints A1 to A6, the processor 40 changes the load limit value L1 of the joints A1 to A6 and temporarily relaxes the level of the safety stop function. Furthermore, after the operation mode ends, the processor 40 restores the load limit value L1 of the joints A1 to A6 to its original value. In other words, the level of the safety stop function can be adjusted according to the operation mode or operation content executed by the robot 1. Therefore, the level of the safety stop function is not lowered more than necessary, and the operation of the robot 1 can be prevented from being excessively restricted by the safety stop function.

[0030] In this embodiment, the processor 40 always applies the increased load limit value L1 while the robot 1 is executing the screw tightening operation mode. Alternatively, if the processor 40 knows that a movement will impose a large load on the joints A1 to A6, it may apply the increased load limit value L1 only to that movement. In this case, the period during which the level of the safety stop function is relaxed can be more limited, making it possible to more reliably protect the robot 1 from overload.

[0031] In this embodiment, the processor 40 may increase the load limit value L1 of each of the joints A1 to A6 in accordance with a parameter included in the control command of the operation program. For example, the processor 40 may increase each load limit value L1 in accordance with the tightening torque (target torque) of the tool T input by the worker operating the robot 1, or the force (target force) pressing the tool T against the workpiece.

[0032] In addition, in this embodiment, the processor 40 increases the load limit values ​​L1 of all of the joints A1 to A6, but instead, it may increase the load limit value L1 of at least one of the joints A1 to A6.

[0033] For example, depending on the operation performed by the robot 1, there may be cases where a load is applied only to the tip of the wrist, and almost no load is applied to the base end of the robot 1. In such cases, the processor 40 may, for example, not change the load limit value L1 of the base end joints A1 to A3, but increase only the load limit value L1 of the tip end joints A4 to A6 in accordance with the operation of the robot 1. Alternatively, the processor 40 may estimate the load acting on the joints A1 to A6 based on the magnitude of the load acting on the hand of the robot 1 during operation, and increase only the load limit value L1 of the joints that are likely to be overloaded.

[0034] In addition, in this embodiment, the processor 40 may acquire the magnitude of the load acting on the joints A1 to A6 of the robot 1 during operation, and increase the load limit value L1 of the joints A1 to A6 based on the acquired magnitude of the load.

[0035] In this case, for example, memory 30 stores threshold values ​​that are slightly smaller than the load limit value L1 of each of joints A1 to A6. Then, processor 40 compares each load acting on joints A1 to A6 detected by sensors S1 to S6 with the corresponding threshold value. If a load exceeding the threshold acts on any joint, processor 40 determines that the load acting on that joint is approaching the load limit value L1 before the load increase, and increases the load limit value L1 of joints A1 to A6. This makes it possible to further limit the period during which the level of the safety stop function is relaxed, thereby more reliably protecting robot 1 from overload.

[0036] Furthermore, in this embodiment, the processor 40 increases the load limit value L1 of each of the joints A1 to A6 in accordance with the movement of the robot 1. In addition, the processor 40 may decrease the load limit value L1 of each of the joints A1 to A6 in accordance with the movement of the robot 1.

[0037] In this case, for example, for operations that are expected to apply only a relatively small load to the joints A1 to A6, the load limit value L1 to be applied can be reduced to make the level of the safety stop function stricter. Therefore, for operations that are expected to apply a large load to the joints A1 to A6, the restrictions imposed by the safety stop function can be relaxed, and for other operations, the safety stop function can be made stricter, thereby strengthening the protection of the robot 1.

[0038] Next, a control device 10' according to a second embodiment of the present disclosure will be described below. In the following description, parts that have the same configuration as the control device 10 described above will be assigned the same reference numerals and descriptions thereof will be omitted.

[0039] The control device 10' according to this embodiment is configured to be connectable to a display device 50 such as a monitor, as shown in Fig. 8. In this case, the processor 40 calculates the ratio between the load acting on at least one of the joints A1 to A6 of the robot 1 during operation and the corresponding load limit value L1. Then, the processor 40 causes the display device 50 to display a graph 51 indicating the magnitude of the calculated ratio, as shown in Fig. 9.

[0040] This allows the operator operating the robot 1 to intuitively and in real time understand the magnitude of the load acting on the joints A1 to A6 of the robot 1 during operation relative to the load limit value L1 by checking the contents displayed on the display device 50. This has the advantage of allowing the operator to immediately detect any abnormalities in the robot 1 during operation.

[0041] In this embodiment, the processor 40 displays the ratio of the load acting on the joints A1 to A6 of the operating robot 1 to the load limit value L1 on the display device 50. Alternatively, the processor 40 may display on the display device 50 the magnitude of each actual load acting on the joints A1 to A6 and the load limit value L1 set for each joint A1 to A6 in association with each other.

[0042] Even with this display method, the worker can confirm how much margin there is for each load acting on the joints A1 to A6 relative to the corresponding load limit value L1. This also has the advantage that the worker can easily understand that each load limit value L1 of the joints A1 to A6 has increased.

[0043] In addition, in this embodiment, the processor 40 may cause the display device 50 to display the ratio of the load acting on the joints A1 to A6 of the robot 1 during operation in association with the operation mode executed by the robot 1.

[0044] 9, the display device 50 displays icons 52 indicating a plurality of operation modes that the robot 1 can execute, and highlights the icon 52 corresponding to the selected operation mode. This allows the operator to easily understand, by checking the display device 50, the correlation between the operation mode being executed by the robot 1 and the ratio of the load acting on the joints A1 to A6 at that time to the load limit value L1.

[0045] Furthermore, in this embodiment, when the processor 40 changes the load limit value L1 set for the joints A1 to A6, the processor 40 may display that fact on the display device 50. For example, as shown in Fig. 9, text 53 indicating whether or not the load limit value L1 for each of the joints A1 to A6 has been changed may be displayed on a part of the display screen.

[0046] Furthermore, in this embodiment, the display device 50 may be configured to notify the user when a load exceeding the load limit value L1 acts on any of the joints A1 to A6. In this case, of the graphs 51 showing the ratios of the loads acting on the joints A1 to A6, only the graph 51 of the joint on which the load exceeds the load limit value L1 acts may be displayed in a color different from that of the other graphs 51. Alternatively, the graphs 51 may be displayed in different colors depending on the ratio of the load acting on the joints A1 to A6 to the load limit value L1.

[0047] Alternatively, when a load exceeding the load limit value L1 acts on any of the joints A1 to A6, a pop-up window for informing the worker of this and urging their attention may be displayed on the screen of the display device 50. Furthermore, this pop-up window may display the joint on which the load exceeding the load limit value L1 is acting, and may also display a proposal for a posture of the robot 1 to reduce the load acting on that joint.

[0048] In addition, in this embodiment, the processor 40 displays the ratio of the load acting on the joints A1 to A6 of the robot 1 during operation on the connected external display device 50, but it may also be displayed on the monitor of the input device 20.

[0049] For example, if the input device 20 is a teaching operation panel, the above-mentioned display contents may be displayed on its monitor, in which case the operator can perform teaching while checking the contents displayed on the monitor of the input device 20. Therefore, the operator can perform teaching work while checking the magnitude of the load acting on the joints A1 to A6 of the robot 1, which makes the teaching work more efficient.

[0050] Furthermore, in each of the above-described embodiments, the control device 10, 10' may be configured to be able to output the loads and load limit values ​​L1 acting on the joints A1 to A6 of the robot 1 during operation. In this case, the control device 10, 10' may be provided with a wired output terminal such as a USB or a wireless communication unit. Furthermore, the loads and load limit values ​​L1 acting on the joints A1 to A6 corresponding to a predetermined operation or a predetermined period may be output by an output icon 54 displayed on the screen of the input device 20 or the display device 50. This allows the operator to easily verify the operation of the robot 1 offline.

[0051] Furthermore, in each of the above-described embodiments, the control devices 10, 10' are configured to control the robot 1, but the control devices 10, 10' may also be configured to control industrial machinery having at least one joint, such as a machine tool.

[0052] Although the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible to these embodiments without departing from the gist of the invention or the concept and spirit of the present invention derived from the content of the claims and their equivalents. 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.

[0053] The following supplementary notes are further disclosed regarding the above embodiments and modifications. (Supplementary Note 1) A control device for causing an industrial machine having at least one joint to perform a task, the control device comprising at least one memory and at least one processor, wherein the memory stores a load limit value of each of the joints and an alteration value for increasing the load limit value, and the processor is capable of altering the load limit value of at least one of the joints based on the alteration value in accordance with a control command for causing the industrial machine to perform the task or a parameter included in the control command. (Supplementary Note 2) The control device according to Supplementary Note 1, wherein the parameter is a target force or a target torque for the task. (Supplementary Note 3) The control device according to Supplementary Note 1 or Supplementary Note 2, wherein the processor returns the altered load limit value to its original magnitude after processing the control command or the parameter. (Supplementary Note 4) A control device for causing an industrial machine having at least one joint to perform a task, the control device comprising: at least one memory for storing a load limit value for each of the joints; and at least one processor, wherein the processor causes a display device to display the load limit value of at least one of the joints or an actual load relative to the load limit value temporarily changed using a change value for changing the load limit value. (Supplementary Note 5) The control device according to Supplementary Note 4, wherein the processor causes the display device to display parameters included in a control command for causing the industrial machine to perform the task. (Supplementary Note 6) The control device according to Supplementary Note 4 or Supplementary Note 5, wherein the processor suggests a change in the posture of the industrial machine when the actual load acting on each of the joints of the industrial machine performing the task exceeds the load limit value of the corresponding joint. (Supplementary Note 7) The control device according to any of Supplements 1 to 6, wherein the processor is capable of outputting the load limit value of each of the joints for a predetermined period of the task and the actual load relative to the load limit value. (Supplementary Note 8) A system of industrial machinery comprising the industrial machine and the control device according to any of Supplements 1 to 7.

[0054] REFERENCE SIGNS LIST 1 Robot (industrial machinery) 10, 10' Control device 20 Input device (display device) 30 Memory 40 Processor 50 Display device 100 Robot system (industrial machinery system) A1, A2, A3, A4, A5, A6 Joint L1 Load limit value

Claims

1. A control device for causing an industrial machine having at least one joint to perform a task, the control device comprising at least one memory and at least one processor, wherein the memory stores a load limit value for each of the joints and a modification value for increasing the load limit value, and the processor is capable of modifying the load limit value of at least one of the joints based on the modification value in accordance with a control command for causing the industrial machine to perform the task or a parameter included in the control command.

2. The control device according to claim 1, wherein the parameter is a target force or a target torque in the task.

3. The control device according to claim 1 or 2, wherein the processor restores the changed load limit value to its original magnitude after processing the control command or the parameter.

4. A control device for causing an industrial machine having at least one joint to perform a task, the control device comprising: at least one memory for storing a load limit value for each of the joints; and at least one processor, the processor causing a display device to display an actual load relative to the load limit value of the at least one joint or the load limit value temporarily changed using a change value for changing the load limit value.

5. The control device according to claim 4, wherein said processor causes said display device to display parameters included in control commands for causing said industrial machine to perform said work.

6. A control device as described in claim 4 or claim 5, wherein the processor proposes a change in the posture of the industrial machine when the actual load acting on each of the joints of the industrial machine performing the work exceeds the load limit value of the corresponding joint.

7. A control device according to any one of claims 1 to 6, wherein the processor is capable of outputting the load limit value of each of the joints during a predetermined period of the work and the actual load relative to the load limit value.

8. An industrial machine system comprising the industrial machine and the control device according to any one of claims 1 to 7.

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