Robot system control method and robot system

Abstract

To make it possible to apply a load evenly to a plurality of support robots when the plurality of support robots support a work-piece in cooperation with each other.SOLUTION: A control method for a robot system 1 comprises: lifting and supporting a work-piece by a plurality of support robots (locator 4) each having a displaceable engagement part 46 in a state of each causing the engagement part thereof to engage with portions, which are different from each other, in the work-piece; in a state of supporting the work-piece, acquiring parameters concerning loads applied respectively to the plurality of support robots; and on the basis of the acquired parameters, changing a position of the engagement part of at least one of the plurality of support robots so that the load applied to the plurality of support robots becomes even.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The technology disclosed herein relates to a control method for a robot system and a robot system. [Background technology]

[0002] Patent Document 1 describes a conventional robot system. The conventional robot system is used in an assembly line for automobile bodies. The conventional robot system employs a monitoring device.

[0003] The monitoring device monitors a plurality of motors that are repeatedly driven through operating and idle periods in an assembly line. The monitoring device includes an initial data storage unit, an observation data storage unit, and a monitoring information providing unit. The initial data storage unit stores, as initial motor data, information on the length of an operating period, the peak current of the operating period, the average current of a constant speed period included in the operating period, and the integrated area of ​​the current for each sub-period into which the operating period is divided, based on a current value over time measured in a normal state of the motor. The observation data storage unit stores, as observation data for each monitoring factor, information on the length of an operating period, the peak current, the average current of the constant speed period, and the integrated area for each sub-period, for each operating period observed during motor operation. The monitoring information providing unit individually compares each piece of the observation data with a critical level previously set corresponding to each piece of the initial data, and provides motor status monitoring information for each monitoring factor. Conventional monitoring devices can detect motor failures in robot systems. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2018-520947 Summary of the Invention [Problem to be solved by the invention]

[0005] In a work area where a robot works on a workpiece, multiple support robots may work together to support the workpiece. For example, the multiple support robots synchronize with each other, with their engagement parts engaging with different parts of the workpiece, to lift and support the workpiece.

[0006] The load is not necessarily evenly distributed across multiple support robots supporting a workpiece. For example, if the center of gravity of a workpiece supported by multiple support robots is shifted from the center between the multiple support robots, the load on the support robot that is farther away from the center of gravity will be relatively greater. Support robots that are subjected to a relatively greater load are more likely to break down than the other support robots. It is required that the load be evenly distributed across multiple support robots that work together to support a workpiece. [Means for solving the problem]

[0007] The technology disclosed herein is a plurality of support robots each having a displaceable engaging portion lifting and supporting the workpiece with the engaging portion engaged with a different portion of the workpiece; Acquire parameters related to the loads applied to each of the plurality of support robots while supporting the workpiece; changing the position of the engagement portion of at least one of the plurality of support robots based on the acquired parameters so that the loads applied to the plurality of support robots are uniform; A method for controlling a robot system. [Effects of the Invention]

[0008] According to the above-described control method for a robot system, when a plurality of support robots cooperate to support a workpiece, it is possible to apply an equal load to the plurality of support robots. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 shows a robot system applied to an automobile manufacturing line. [Figure 2] Figure 2 shows the robot system. [Figure 3] FIG. 3 is a block diagram of the robot system. [Figure 4] FIG. 4 is a schematic diagram of a locator. [Figure 5] FIG. 5 is a flowchart showing the control procedure of the robot system regarding support of a workpiece. [Figure 6] FIG. 6 shows an example of changes in the current value supplied to the third motor of each of the first, second, third and fourth locators. [Figure 7] FIG. 7 is a flowchart showing the control procedure of the locator in the calibration mode. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of a robot diagnostic system will be described with reference to the drawings. The robot diagnostic system described here is an example.

[0011] Fig. 1 is a perspective view of the robot system 1 seen from diagonally above. Fig. 2 is a rear view of the robot system 1 seen from behind. The robot system 1 is applied to a production line 10 in an automobile factory. In the illustrated production line 10, welding, more specifically spot welding, is performed on an automobile body 11.

[0012] The front Fr, rear Rr, right Rt, left Lt, up Up, and down Lw of the robot system 1 are defined as follows, with the body 11 that is the work target of the robot system 1 as the reference.

[0013] The front Fr of the robot system 1 is the left rear side in the direction connecting the right front and left rear of the paper in Figure 1. The front Fr of the robot system 1 corresponds to the front of the automobile body 11, and the rear Rr of the robot system 1 corresponds to the rear of the automobile body 11. The front-to-rear direction corresponds to the conveyance direction of the body 11.

[0014] The right side Rt of the robot system 1 is the far right side in the direction connecting the front left and rear right of the paper in FIG. 1. The right side Rt of the robot system 1 corresponds to the right side of the automobile body 11. The left side Lt of the robot system 1 corresponds to the left side of the automobile body 11. The left-right direction is a direction that is horizontally perpendicular to the front-rear direction.

[0015] The top (Up) of the robot system 1 is the top side of the paper in Fig. 1, and the bottom (Lw) of the robot system 1 is the bottom side of the paper. The top and bottom of the robot system 1 correspond to the top and bottom of the automobile body 11. The up-down direction is a direction perpendicular to the front-to-rear direction.

[0016] The above definitions are used to explain the robot system 1, and are not used to limit the structure or configuration of the robot system 1 and the elements included in the robot system 1 disclosed herein.

[0017] The robot system 1 includes a robot 2. The robot 2 is an example of a work robot. The robot 2 performs work on a workpiece transported to a work area 13. The work area 13 is located on a path 15 of the AMR 6, which will be described later, and refers to an area where the workpiece transported by the AMR 6 stays to be worked on by the robot 2. The workpiece of the robot 2 is a body 11. The work that the robot 2 performs on the body 11 is welding.

[0018] The robot 2 is a vertical articulated robot having five to seven axes. As shown in Fig. 2, the robot 2 has a welding gun 21 as an end effector. However, the robot 2 is not limited to a vertical articulated robot.

[0019] The robot system 1 includes a plurality of robots 2. The robot system 1 shown in the figure includes 12 robots 2. The 12 robots 2 are located on either side of the body 11. On the right side of the body 11, six robots 2 are lined up in the front-to-rear direction of the body 11. Similarly, on the left side of the body 11, six robots 2 are lined up in the front-to-rear direction of the body 11. Each robot 2 performs welding at a different location on the body 11. Note that the number of robots 2 in the robot system 1 is not limited to a specific number. Furthermore, the arrangement of the robots 2 in the robot system 1 is not limited to a specific arrangement.

[0020] The robot system 1 is equipped with a locator 4. The locator 4 is an example of a support robot. As shown by the dashed dotted line in Figure 2, the locator 4 lifts and supports the body 11 while the robot 2 is working. The locator 4 in the illustration is a three-axis Cartesian robot. The locator 4 has a rod 45 that engages with the body 11. The rod 45 extends in the left-right direction. An engagement portion 46 at the tip of the rod 45 engages with the body 11. The locator 4 changes the position of the engagement portion 46 in the front-back, left-right, and up-down directions. Details of the structure of the locator 4 will be described later.

[0021] The robot system 1 is equipped with a plurality of locators 4. The robot system 1 in the illustration is equipped with eight locators 4. The eight locators 4 are located on the left and right sides of the body 11. On the right side of the body 11, four locators 4 are lined up in the front-to-rear direction of the body 11. One of the four locators 4 supports the right front end of the body 11, and one of the four locators 4 supports the right rear end of the body 11. The remaining two locators support the right central portion of the body 11, as shown in FIG. 1. Similarly, on the left side of the body 11, four locators 4 are lined up in the front-to-rear direction of the body 11. One of the four locators 4 supports the left front end of the body 11, and one of the four locators 4 supports the left rear end of the body 11. The remaining two locators support the left central portion of the body 11, as shown in FIG. 1.

[0022] In the following description, the locator 4 supporting the right front end of the body 11 is referred to as the first locator 41, the locator 4 supporting the right rear end of the body 11 is referred to as the second locator 42, the locator 4 supporting the left front end of the body 11 is referred to as the third locator 43, and the locator 4 supporting the left rear end of the body 11 is referred to as the fourth locator 44. When there is no need to distinguish between the first locator 41, the second locator 42, the third locator 43, and the fourth locator 44, they are simply referred to as locators 4. Note that it is sufficient for there to be multiple locators 4 in the work area 13, and the number of locators 4 located in the work area 13 is not limited to a specific number.

[0023] The robot system 1 is equipped with one or more transport vehicles. The transport vehicle transports a workpiece to a work area 13. The transport vehicle is an autonomous mobile transport robot (AMR) 6. The AMR 6 travels on a flat floor in a factory. As illustrated in FIG. 2, the body 11 is placed on a carriage 14. The AMR 6 is located below the carriage 14 and engages with the carriage 14. The AMR 6 transports the body 11 via the carriage 14. Note that the AMR 6 may directly support the body 11 without using the carriage 14. Note that the appearance of the AMR 6 shown in FIG. 1 or 2 is an example. The body 11 transported to the work area 13 by the AMR 6 is handed over from the AMR 6 to multiple locators 4.

[0024] FIG. 3 is a block diagram of the robot system 1. The robot system 1 includes a system controller 16. The system controller 16 controls the entire robot system 1. The system controller 16 has a processor 16a, a memory 16b, and an I / O bus 16c. The processor 16a includes one or more CPUs. The processor 16a is configured with one or more chips. The processor 16a is configured with RAM (Random Access Memory) and ROM (Read Only Memory). The processor 16a is, for example, a non-volatile memory. The I / O bus 16c is an input / output bus that inputs and outputs electrical signals to and from the processor 16a.

[0025] The robot system 1 includes a robot controller 17. Note that the robot controller 17 is not an essential element of the robot system 1. The robot controller 17 is electrically connected to the system controller 16. The electrical connection includes a wired or wireless connection. The robot controller 17 is also electrically connected to the robot 2. The robot controller 17 and the robot 2 are connected one-to-one. The robot system 1 includes the same number of robot controllers 17 as the number of robots 2.

[0026] The robot controller 17 controls the robot 2. More specifically, the robot controller 17 receives a control signal from the system controller 16 and outputs a control signal to the robot 2. The robot 2 receives the control signal from the robot controller 17 and performs welding work on the body 11.

[0027] The robot system 1 includes a locator controller 18. The locator controller 18 is electrically connected to the system controller 16. The electrical connection may be wired or wireless. The locator controller 18 is also electrically connected to each of a total of eight locators 4, including a first locator 41, a second locator 42, a third locator 43, and a fourth locator 44.

[0028] The locator controller 18 controls the locators 4. More specifically, the locator controller 18 receives a control signal from the system controller 16 and outputs a control signal to the locator 4. The locator 4 receives the control signal from the locator controller 18 and positions and supports the body 11 delivered from the AMR 6 at a predetermined position. As will be described later, the locator controller 18 controls the multiple locators 4 in synchronization. The synchronized control enables the multiple locators 4 to adjust the position of the body 11 and support the body 11.

[0029] The robot system 1 is equipped with a sensor 19. The sensor 19 is electrically connected to the system controller 16. The sensor 19 outputs a signal related to the position of the body 11 that has arrived at the work area 13 to the system controller 16, as will be described in detail later. The sensor 19 includes an external camera 191. The external camera 191 is positioned above the work area 13, as shown in FIG. 2. The external camera 191 photographs the body 11 positioned in the work area 13 from above. The image captured by the external camera 191 is sent to the system controller 16. The system controller 16 determines the degree of inclination of the body 11, for example, in a horizontal plane, based on the image captured by the external camera 191.

[0030] (Locator structure) FIG. 4 is a perspective view of the locator 4. For the purpose of explaining the locator 4, the directions of the X-axis, Y-axis, and Z-axis are defined as follows. The X-axis is a horizontal axis, and corresponds to the left-right direction of the robot system 1 when the locator 4 is installed in the work area 13. The Y-axis is a horizontal axis, and is an axis perpendicular to the X-axis. The Y-axis corresponds to the front-rear direction of the robot system 1 when the locator 4 is installed in the work area 13. The Z-axis is a vertical axis, and is an axis perpendicular to the X-axis and Y-axis. The Z-axis corresponds to the up-down direction of the robot system 1 when the locator 4 is installed in the work area 13.

[0031] As described above, the locator 4 is a three-axis Cartesian robot. The locator 4 has a support mechanism 40. The support mechanism 40 includes the rod 45 described above. The rod 45 supports the body 11 from below. The rod 45 extends in the direction of the X-axis.

[0032] The support mechanism 40 includes an engagement portion 46. The engagement portion 46 is located at the tip of the rod 45. The engagement portion 46 has a pin extending in the Z-axis direction. The pin is inserted into an engagement hole in the body 11 from below. The engagement hole in the body 11 opens downward at the bottom of the body 11. When the pin is inserted into the engagement hole, the engagement portion 46 engages with the body 11.

[0033] The locator 4 has a base 47. The base 47 is fixed to the floor surface. The support mechanism 40 includes a first stage 410, a second stage 420, and a third stage 430. The first stage 410 moves relative to the base 47 in the X-axis direction. The second stage 420 moves relative to the first stage 410 in the Y-axis direction. The third stage 430 moves relative to the second stage 420 in the Z-axis direction. The rod 45 is fixed to the third stage 430. The support mechanism 40 displaces the rod 45 in the X-axis, Y-axis, and Z-axis directions.

[0034] The first stage 410 is operated by a first motor 411. The second stage 420 is operated by a second motor 421. The third stage 430 is operated by a third motor 431. The first motor 411, the second motor 421, and the third motor 431 are servo motors. The first motor 411, the second motor 421, and the third motor 431 may be DC motors or AC motors.

[0035] (Supporting the work by the locator) The multiple locators 4 in the work area 13 receive the body 11 from the AMR 6. Specifically, when the body 11 is transported to the work area 13, each of the multiple locators 4 activates the first stage 410, the second stage 420, and the third stage 430 to engage the engagement portion 46 with the body 11. The multiple locators 4 move the third stage 430 upward with the engagement portion 46 engaged with the body 11. The rods 45 of the multiple locators 4 support the body 11 from below with the body 11 raised above the carriage 14.

[0036] When the AMR 6 arrives at the designated work area 13, the orientation of the AMR 6 may be tilted from a predetermined orientation. This is because the AMR 6 does not require a guide, such as a rail, that mechanically engages to regulate the orientation of the AMR 6. If the orientation of the AMR 6 is tilted, the orientation of the body 11 being transported by the AMR 6 will also be tilted from the reference orientation.

[0037] Therefore, the multiple locators 4 operate the first stage 410 and the second stage 420 while supporting the body 11, to adjust the position of the body 11. The amount of movement of each stage 410, 420 is calculated by the system controller 16 based on an image of the body 11 captured by the external camera 191.

[0038] Instead of multiple locators 4 adjusting the position of body 11 , AMR 6 that has arrived at work area 13 may adjust the position of body 11 before handing over body 11 to locator 4 .

[0039] Once the locator 4 supports the body 11 so that the body 11 is in a predetermined position, the robot 2 begins welding the body 11. Once the robot 2 has completed its work, the locator 4 hands over the body 11 to the AMR 6.

[0040] Here, when the body 11 is supported by a plurality of locators 4, the value of the current supplied to the first motor 411 of each locator 4 is acquired by a first current sensor 414. The value of the current supplied to the second motor 421 is acquired by a second current sensor 424. The value of the current supplied to the third motor 431 is acquired by a third current sensor 434. Note that the first current sensor 414, the second current sensor 424, and the third current sensor 434 are not essential elements of the robot system 1.

[0041] When the first motor 411, the second motor 421, and the third motor 431 are DC motors, the first detected current value, the second detected current value, and the third detected current value are the magnitude of the current itself supplied to the motors. When the first motor 411, the second motor 421, and the third motor 431 are AC motors, the first detected current value, the second detected current value, and the third detected current value are the magnitude of the amplitude of the current supplied to the motors. Note that when the first motor 411, the second motor 421, and the third motor 431 are AC motors, the first detected current value, the second detected current value, and the third detected current value may be the current value of the q-axis current.

[0042] 5 shows the control procedure of the robot system 1 regarding the support of the body 11 by the locator 4. In step S11 after starting, the system controller 16 determines whether the AMR 6 carrying the body 11 has stopped in the work area 13. Step S11 is repeated until the AMR 6 has stopped in the work area 13.

[0043] When the AMR 6 stops in the work area 13, in step S12, the system controller 16 causes the engaging portions 46 of the multiple locators 4 to engage with the body 11 via the locator controller 18. The multiple locators 4 then lift the body 11.

[0044] In step S13, the multiple locators 4 that have lifted the body 11 adjust the position of the body 11. Once the body 11 is positioned at a predetermined position, the multiple locators 4 support the body 11 in step S14. Once the locators 4 support the body 11, the robot 2 starts working on the body 11.

[0045] In the following step S15, the system controller 16 determines whether the work of the robot 2 has finished. If the work has not finished, in step S14, the locator 4 continues to support the body 11. If the work of the robot 2 has finished, in step S16, the locator 4 ends supporting the body 11. In other words, the body 11 is handed over from the locator 4 to the AMR 6. Having received the body 11, the AMR 6 resumes transporting the body 11.

[0046] (Locator Calibration) In the robot system 1, a plurality of locators 4 cooperate to support the body 11. It is preferable that the load is applied evenly to the plurality of locators 4, but the load applied to the plurality of locators 4 is not necessarily uniform.

[0047] FIG. 6 shows an example of the third detected current values ​​of the first locator 41, the second locator 42, the third locator 43, and the fourth locator 44. The vertical axis represents the third detected current value, and the horizontal axis represents time. Basically, the motor's output increases as the current value supplied increases. The load on the motor is proportional to the current value supplied.

[0048] It can be seen that all current values ​​peak and then become approximately constant. The portion where the current value peaks corresponds to the moment when the rod 45 supports the body 11. The shift in the peak position is due to the difference in the timing at which the multiple locators 4 support the body 11. In the example of FIG. 6, after the first locator 41 supports the body 11 at time t1, the second locator 42 and the third locator 43 support the body 11 at time t2, and then the fourth locator 44 supports the body 11 at time t3. The peak values ​​Imax1, Imax2, Imax3, and Imax4 of each locator 4 vary depending on the load on the third motor 431. As times t1, t2, and t3 pass, the number of locators 4 supporting the body 11 increases and the load on the third motor 48 decreases, so the later the locator 4 supports the body 11, the smaller the peak value of the current.

[0049] The current value after the peak becomes a substantially constant steady-state value. The magnitudes of the steady-state values ​​Iz1, Iz2, Iz3, and Iz4 vary depending on the position of the center of gravity of the body 11. Since the moment increases with distance from the center of gravity of the body 11, the steady-state value of a locator 4 that supports a position farther from the center of gravity of the body 11 becomes larger than that of a locator 4 that supports a position closer to the center of gravity. In the example of FIG. 6, the second locator 42 and the third locator 43 support the position farthest from the center of gravity, the fourth locator 44 supports a position closer to the center of gravity than the second locator 42 and the third locator 43, and the first locator 41 supports the position closest to the center of gravity.

[0050] During the welding operation of the robot 2, among the plurality of locators 4 supporting the body 11, the locator 4 that is subjected to a relatively large load is more likely to break down than the other locators 4.

[0051] Therefore, in the robot system 1, calibration related to the support of the body 11 by the locators 4 is performed, for example, when teaching the robot 2. In other words, the robot system 1 has a calibration mode. The purpose of the calibration is to equalize the loads on the multiple locators 4 when the multiple locators 4 support the body 11. The calibration procedure will be described below. In the following explanation, the calibration procedure will be described using an example in which four locators 4, namely, first, second, third, and fourth locators 41, 42, 43, and 44, support the body 11. As described above, the first, second, third, and fourth locators 41, 42, 43, and 44 are locators that support the right front end, right rear end, left front end, and left rear end of the body 11, respectively.

[0052] During calibration, the first, second, third, and fourth locators 41, 42, 43, and 44 support the body 11. The body 11 supported by the locators 4 at this time is a master workpiece. The master workpiece is a workpiece used to teach the robot 2, and serves as a reference for the body 11 to be welded.

[0053] In a state in which the first, second, third, and fourth locators 41, 42, 43, and 44 support the body 11, the system controller 16 acquires the third detected current values ​​detected by the third current sensors 434 of the first, second, third, and fourth locators 41, 42, 43, and 44, respectively, via the locator controller 18. For example, data on the third detected current values ​​that changes over time, as shown in FIG. 6, is acquired.

[0054] The system controller 16 also calculates time differential values ​​of the current values ​​at time t4 based on the acquired third detected current values ​​of each of the first, second, third, and fourth locators 41, 42, 43, and 44. Time t4 corresponds to a state in which the multiple locators 4 support the master workpiece so that it remains stationary at a predetermined position. The motors 411, 421, and 431 of the locators 4 are servo-controlled. The time differential values ​​of the current values ​​of the first locator 41, the second locator 42, the third locator 43, and the fourth locator 44 at time t4 are represented as Iz1(t4-t4'), Iz2(t4-t4'), Iz3(t4-t4'), and Iz4(t4-t4'), respectively. In a state in which multiple locators 4 support a master workpiece so that it remains stationary at a predetermined position, a locator 4 with a large time derivative of the current value corresponds to a locator 4 that is subjected to a relatively large load, and a locator 4 with a small time derivative of the current value corresponds to a locator 4 that is subjected to a relatively small load. The system controller 16 also determines the maximum value Izmax(t4) and the minimum value Izmin(t4) of the calculated time derivatives of the current value.

[0055] Once the locator 4 under the maximum load is identified, the system controller 16 moves the third stage 430 of one of the locators 4 slightly upward or downward via the locator controller 18. For example, the third stage 430 of the locator 4 under the maximum load may be moved slightly upward or downward. At time t5 after moving the third stage 430, the system controller 16 again calculates time derivatives Iz1(t5-t5'), Iz2(t5-t5'), Iz3(t5-t5'), and Iz4(t5-t5') of the current values ​​based on the acquired third detected current values ​​of the first, second, third, and fourth locators 41, 42, 43, and 44. The system controller 16 also determines the maximum value Izmax(t5) and the minimum value Izmin(t5) of the calculated time derivatives of the current values.

[0056] The system controller 16 calculates the current variations dI(t4) = Izmax(t4) - Izmin(t4) and dI(t5) = Izmax(t5) - Izmin(t5). Small current variations correspond to equal or nearly equal loads on the multiple locators 4. The system controller 16 repeatedly changes the position of the third stage 430 of the locator 4 as necessary so that dI(t5) is smaller than dI(t4). When the loads on the multiple locators 4 become equal or nearly equal, the calibration is complete. The system controller 16 stores the positions of the third stage 430 of each of the multiple locators 4 set by the calibration in the memory 16b. After the calibration, the system controller 16 and the locator controller 18 control the multiple locators 4 to support the body 11 based on the positions of the third stage 430 stored in the memory 16b.

[0057] 7 is a flowchart showing the control procedure for the locator 4 in the calibration mode. First, in step S21 after starting, the system controller 16 causes the engaging portions 46 of each of the multiple locators 4 to engage with the master workpiece via the locator controller 18. Thereafter, in step S22, the multiple locators 4 lift up and support the master workpiece.

[0058] In step S23, the system controller 16 acquires the third detected current value of each of the multiple locators 4. In the following step S24, the system controller 16 slightly moves the third stage 430 of a specific locator 4 upward or downward based on the acquired third detected current value. Thereafter, in step S25, the system controller 16 acquires the third detected current value of each of the multiple locators 4, and in step S26, determines whether the loads on the multiple locators 4 are equal or approaching equality. If the determination in step S26 is No, the system controller 16 repeats steps S24 and S25. If the determination in step S27 is Yes, the system controller 16 ends the calibration of the locators 4 in step S27. In step S28, the system controller 16 stores the positions of the first stage 410, the second stage 420, and the third stage 430 of each of the multiple locators 4 in memory 16b.

[0059] Then, in step S29 after step S28, in a state where the master workpiece is supported by the plurality of locators 4, the robot 2 is taught about the spot welding operation.

[0060] (Action and effect) In the robot system 1, each of the multiple locators 4 lifts and supports the body 11. In calibrating the locators 4, the position of the engagement portion 46 of at least one of the multiple locators 4 is changed so that the loads on the multiple locators 4 are equalized. Through the calibration, the loads on the multiple locators 4 are equalized or approaching equalization. During operation of the production line 10, an excessive load is prevented from being applied to a specific locator 4 among the multiple locators 4 supporting the body 11. This prevents a locator 4 that is subjected to an excessive load from breaking down.

[0061] Furthermore, in the calibration, the load acting on the locator 4 is identified based on the third detected current value supplied to the third motor 431, so that the load acting on the locator 4 in the vertical direction can be accurately identified.

[0062] Furthermore, the posture of the master workpiece supported by the locator 4 is determined by calibration of the locator 4. Following calibration of the locator 4, teaching of the robot 2 is performed. Since the posture of the master workpiece has been determined, teaching of the robot 2 can be performed appropriately.

[0063] (Variation) 7, instead of slightly moving the third stage 430 of the locator 4 upward or downward, the first stage 410 or the second stage 420 of the locator 4 may be slightly moved. Also, in step S24, each of the first, second, and third stages 410, 420, 430 of the locator 4 may be slightly moved.

[0064] 7 is not limited to the third detected current value of the third motor 431. In step S23 or S25, the system controller 16 may acquire the first detected current value of the first motor 411. In step S24, the system controller 16 may slightly move the first stage 410, the second stage 420, or the third stage 430 based on the differential value of the first detected current value so that the load on the first motor 411 is uniform among the multiple locators 4.

[0065] Similarly, in step S23 or S25, system controller 16 may acquire a second detected current value of second motor 421. In step S24, system controller 16 may slightly move first stage 410, second stage 420, or third stage 430 based on the differential value of the second detected current value so that the load on second motor 421 is uniform among the multiple locators 4.

[0066] The locator 4 as a support robot is not limited to a three-axis Cartesian robot. The support robot may be an articulated robot. The diagnostic device 7 individually diagnoses the lifespan of a plurality of articulated robots.

[0067] The robot system 1 may include an AGV (Automatic Guided Vehicle) as a transport mechanism instead of the AMR 6. The transport mechanism is not limited to a mechanism using an AMR 6 or AGV that travels autonomously.

[0068] The system controller 16 may be omitted from the robot system 1. The robot system 1 may achieve the above-described control through mutual communication between the robot controller 17, the locator controller 18, and the AMR 6. When the system controller 16 is omitted, the locator controller 18 may calibrate the locator 4.

[0069] It should be noted that the work performed by the robot system 1 disclosed herein in the manufacturing line 10 is not limited to welding. Furthermore, the workpiece that the robot system 1 acts on is not limited to the automobile body 11. Furthermore, the robot system 1 is not limited to application to the automobile manufacturing line 10.

[0070] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0071] (Aspect) The above-described embodiments are examples of the following aspects.

[0072] (Aspect 1) A plurality of support robots (4) each having a displaceable engaging portion (46) lifts and supports the workpiece (11) in a state in which the engaging portion (46) is engaged with a different portion of the workpiece (11), While supporting the workpiece (11), parameters relating to the load acting on each of the plurality of support robots (4) are acquired; changing the position of the engaging portion (46) of at least one of the plurality of support robots (4) based on the acquired parameters so that the loads applied to the plurality of support robots (4) are uniform; A method for controlling a robot system (1).

[0073] When each of the multiple support robots 4 lifts and supports the workpiece 11, the position of the engagement portion 46 of at least one of the multiple support robots 4 is changed so that the load on the multiple support robots 4 is uniform. This prevents an excessive load from being applied to a specific support robot 4. This prevents the support robot 4 from breaking down due to an excessive load.

[0074] (Aspect 2) The support robot (4) has motors (411, 421, 431) for displacing the engagement portion (46), The control method for a robot system (1) according to aspect 1, wherein the parameter is a current value supplied to the motor (411, 421, 431) of the support robot (4) that supports the workpiece (11) so that the workpiece (11) remains stationary.

[0075] The load on the support robot (4) can be accurately determined based on the current value supplied to the motors (411, 421, 431).

[0076] (Aspect 3) the support robot (4) is a three-axis Cartesian robot that displaces the engagement portion (46) in the directions of an X-axis and a Y-axis that are orthogonal to each other in a horizontal plane, and in the directions of a vertical Z-axis, The control method for a robot system (1) according to aspect 1 or 2, wherein the engagement portion (46) is displaced in at least one direction of the X-axis, the Y-axis, and the Z-axis so that the load on the multiple support robots (4) is uniform.

[0077] The multiple three-axis Cartesian robots cooperate to efficiently support the workpiece 11. Furthermore, by changing the positions of the engagement portions 46 of the three-axis Cartesian robots, the loads applied to the multiple three-axis Cartesian robots supporting the workpiece 11 become equal or approach equal.

[0078] (Aspect 4) A control method for a robot system (1) according to any one of aspects 1 to 3, wherein the positions of the engagement portions (46) are changed so that the loads on the plurality of support robots (4) are evenly distributed, and then a working robot (2) is taught about the workpiece (11) supported by the plurality of support robots (4).

[0079] With the plurality of support robots (4) properly supporting the workpiece (11), the working robot (2) is taught about the workpiece (11), so that the teaching of the working robot (2) is also carried out properly.

[0080] (Aspect 5) a plurality of support robots (4) each having a displaceable engagement portion (46) and configured to lift and support the workpiece (11) with the engagement portion (46) engaged with different portions of the workpiece (11); a controller (16) that acquires parameters relating to the loads applied to each of the plurality of support robots (4) while supporting the workpiece (11), and changes the position of the engaging portion (46) of at least one of the plurality of support robots (4) based on the acquired parameters so that the loads applied to the plurality of support robots (4) are uniform; A robot system (1) comprising:

[0081] The robot system (1) can prevent an excessive load from being placed on a specific support robot (4), thereby preventing the support robot (4) from breaking down due to an excessive load. [Explanation of symbols]

[0082] 1. Robot System 11 Body (work) 16 Controller (System Controller) 2. Robots (working robots) 4 Locator (support robot) 41 First Locator (Support Robot) 42 Second Locator (Support Robot) 43 Third Locator (Support Robot) 44 4th Locator (Support Robot) 46 Engagement part

Claims

1. a plurality of support robots each having a displaceable engaging portion lifting and supporting the workpiece with the engaging portion engaged with a different portion of the workpiece; Acquire parameters related to the loads applied to each of the plurality of support robots while supporting the workpiece; changing the position of the engagement portion of at least one of the plurality of support robots based on the acquired parameters so that the loads applied to the plurality of support robots are uniform; A method for controlling a robotic system.

2. 2. The method for controlling a robot system according to claim 1, the support robot has a motor for displacing the engagement portion, the parameter is a current value supplied to the motor of the support robot supporting the workpiece so that the workpiece remains stationary; A method for controlling a robotic system.

3. 2. The method for controlling a robot system according to claim 1, the support robot is a three-axis Cartesian robot that displaces the engagement portion in directions of an X-axis and a Y-axis that are orthogonal to each other in a horizontal plane, and in directions of a vertical Z-axis, the engaging portion is displaced in at least one direction of the X-axis, the Y-axis, and the Z-axis so that loads applied to the plurality of support robots are uniform; A method for controlling a robotic system.

4. 4. The method for controlling a robot system according to claim 1, After changing the positions of the engagement parts so that the loads on the plurality of support robots are uniform, teaching of the work robot is further performed for the workpieces supported by the plurality of support robots. A method for controlling a robotic system.

5. a plurality of support robots each having a displaceable engagement portion, the support robots lifting and supporting the workpiece with the engagement portion engaged with different portions of the workpiece; a controller that acquires parameters relating to the loads applied to each of the plurality of support robots while the workpiece is being supported, and changes the position of the engagement portion of at least one of the plurality of support robots based on the acquired parameters so that the loads applied to the plurality of support robots are equalized; A robot system comprising:

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