Monitoring system

Abstract

To easily grasp the causes behind changes in a load of a motor.SOLUTION: A monitoring system 3 includes: a plurality of locators 4 that have an arm 41 moving according to a motor (a third motor 48), and that align a workpiece (a body 11) conveyed to a work area 13 at mutually different positions; and a monitoring device 30 for calculating for each locator 4, a comparison value obtained by comparing a current value supplied to the motor, and a representative value which is set for each locator 4 and is associated with the current value.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The technology disclosed herein relates to a surveillance system. [Background technology]

[0002] Patent Document 1 discloses a vehicle body assembly line. The assembly line described in Patent Document 1 includes multiple multi-axis robots that position the underbody and an AGV that transports the underbody to an assembly area. Each multi-axis robot lifts the underbody from below and holds it at a predetermined height. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6887738 Summary of the Invention [Problem to be solved by the invention]

[0004] In a motor-driven robot, acquiring the load on the motor is effective in understanding the operating state of the motor. However, when a workpiece is supported by multiple robots, as in Patent Document 1, the load on each robot changes depending on the shape or posture of the workpiece. Simply acquiring the motor load for each robot independently makes it difficult to understand the cause of the change in motor load. [Means for solving the problem]

[0005] The technology disclosed herein relates to a monitoring system that includes a plurality of locators each having an arm moved by a motor, which aligns a workpiece transported to a work area at a different position relative to each other, and a monitoring device that calculates a comparison value for each locator by comparing a current value supplied to the motor with a representative value set for each locator and associated with the current value. [Effects of the Invention]

[0006] The current value supplied to the motor reflects the load on the motor. According to the monitoring system, by calculating a comparison value of the current value for each locator, it becomes easier to understand the cause of changes in the load on the motor. [Brief explanation of the drawings]

[0007] [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 schematic diagram of a monitoring system. [Figure 6] FIG. 6 is a schematic diagram showing the screen of the display device. [Figure 7] FIG. 7 is a flowchart showing a process for obtaining a representative value by the monitoring system. [Figure 8] FIG. 8 is a flowchart showing a process of monitoring the comparison value by the monitoring system. [Figure 9] FIG. 9 is a flowchart showing a process of monitoring a comparison value by the monitoring system according to the first modification. [Figure 10] FIG. 10 is a flowchart showing a process of monitoring a comparison value by a monitoring system according to the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of a monitoring system will be described with reference to the drawings. The monitoring system described here is an example.

[0009] (Overall structure of the robot system) FIG. 1 is a perspective view of a robot system 1 to which a monitoring system is applied, 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. The body 11 is an example of a workpiece.

[0010] 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.

[0011] 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 body 11 of the automobile, and the rear Rr of the robot system 1 corresponds to the rear of the body 11 of the automobile.

[0012] The right side Rt of the robot system 1 is the right rear side in the direction connecting the left front and right rear of the page. The right side Rt of the robot system 1 corresponds to the right of the automobile body 11. The left side Lt of the robot system 1 is the left front side in the direction connecting the left front and right rear of the page. The left side Lt of the robot system 1 corresponds to the left of the automobile body 11.

[0013] The top (Up) of the robot system 1 is the top side of the paper, 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 body 11 of the automobile.

[0014] It should be noted that 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.

[0015] The robot system 1 includes a robot 2. The robot 2 performs work on a workpiece transported to a work area 13. The work area 13 is located on a transport path 15 of an AMR (Autonomous Mobile Robot) 6, and refers to an area where the workpiece of the robot 2 is located when the AMR 6 stops. The workpiece of the robot 2 is a body 11. The work that the robot 2 performs on the body 11 is welding.

[0016] 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.

[0017] 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. Similarly, on the left side of the body 11, six robots 2 are lined up in the front-to-rear direction of the body. Each robot 2 performs welding at a different location on the body 11. 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.

[0018] The robot system 1 includes a locator 4. As indicated by the dashed line in FIG. 2, the locator 4 supports the body 11 while the robot 2 is working. While supporting the body 11, the locator 4 aligns the body 11. The detailed configuration of the locator 4 will be described later.

[0019] The robot system 1 is equipped with multiple locators 4. The robot system 1 in the illustration is equipped with four locators 4. The four locators 4 are located on the left and right sides of the body 11. On the left side of the body 11, two locators 4 are lined up in the front-to-rear direction of the body. One of the two locators 4 supports the left front end of the body 11, and the other of the two locators 4 supports the left rear end of the body 11. Similarly, on the right side of the body 11, two locators 4 are lined up in the front-to-rear direction of the body. One of the two locators 4 supports the right front end of the body 11, and the other of the two locators 4 supports the right rear end of the body 11. Hereinafter, the locator 4 arranged on the left front side will be referred to as the first locator 4a, the locator 4 arranged on the left rear side will be referred to as the second locator 4b, the locator 4 arranged on the right front side will be referred to as the third locator 4c, and the locator 4 arranged on the right rear side will be referred to as the fourth locator 4d. When there is no need to distinguish between the four locators 4, they will simply be referred to as locators 4. The first locator 4a, second locator 4b, third locator 4c, and fourth locator 4d have the same configuration but are arranged differently.

[0020] The first locator 4a and the third locator 4c are located at the same position in the front-rear direction, and the second locator 4b and the fourth locator 4d are located at the same position in the front-rear direction.

[0021] The robot system 1 includes a support device 5. The support device 5 supports the body 11 while the robot 2 is working. Note that the support device 5 is not an essential element of the robot system 1.

[0022] The robot system 1 includes a plurality of support devices 5. The robot system 1 shown in the figure includes four support devices 5. The four support devices 5 are located on the left and right sides of the body 11. On the left side of the body 11, two support devices 5 are lined up in the front-to-rear direction of the body 11 between the first locator 4a and the second locator 4b. The two support devices 5 support the left front center portion of the body 11. Similarly, on the right side of the body 11, two support devices 5 are lined up in the front-to-rear direction of the body 11 between the third locator 4c and the fourth locator 4d. The two support devices 5 support the right center portion of the body 11.

[0023] The configuration of each support device 5 is the same as that of the locator 4. The support device 5 has an arm that supports the body 11 from below. In this embodiment, each support device 5 does not align the body 11, but only supports the body 11 from below. Note that each support device 5 can also be used as a locator. For example, when the size of the workpiece in the front-to-rear direction is small, the support device 5 is used as a locator, and the workpiece is aligned by the support device 5.

[0024] The robot system 1 includes one or more transport vehicles. The transport vehicles transport workpieces to a work area 13. The transport vehicles are autonomous mobile robots (AMRs) 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.

[0025] 3 is a block diagram of the robot system 1. The robot system 1 includes a system controller 16. However, the system controller 16 is not an essential element of the robot system 1. The system controller 16 controls the entire robot system 1.

[0026] 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.

[0027] 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.

[0028] The robot system 1 includes a locator controller 18. However, the locator controller 18 is not an essential element of the robot system 1. The locator controller 18 is electrically connected to the system controller 16. The electrical connection may be a wired or wireless connection. The locator controller 18 is also electrically connected to the multiple locators 4.

[0029] The locator controller 18 controls the locator 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.

[0030] The robot system 1 includes a sensor 20. The sensor 20 is electrically connected to the system controller 16. The sensor 20 includes an external camera 191, which will be described later.

[0031] As shown in FIG. 2, the external camera 191 is positioned above the work area 13. The external camera 191 photographs the body 11 positioned in the work area 13 from above. The image photographed 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 in the horizontal plane based on the image photographed by the external camera 191.

[0032] (Configuring Locators) The locator 4 is a three-axis Cartesian robot. The locator 4 has an arm 41 that supports the body 11 from below. The arm 41 extends in the left-right direction. The arm 41 has a pin 41a at its tip. The pin 41a is connected to the body 11.

[0033] 4, the locator 4 has a base 42 fixed to the floor surface, a first stage 43 that moves left and right, a second stage 44 that moves forward and backward, and a third stage 45 that moves up and down. The arm 41 is connected to the third stage 45.

[0034] The first stage 43 is actuated by a first motor 46. The second stage 44 is actuated by a second motor 47. The third stage 45 is actuated by a third motor 48. The second stage 44, the third stage 45, and the arm 41 move left and right as the first stage 43 moves left and right. The third stage 45 and the arm 41 move forward and backward as the second stage 44 moves forward and backward. The arm 41 moves up and down as the third stage 45 moves up and down. The first motor 46, the second motor 47, and the third motor 48 may be DC motors or AC motors.

[0035] In the flow of movement of the first stage 43, second stage 44, and third stage 45 from the base 42 to the arm 41, the base 42 side is the proximal end side and the arm 41 side is the distal end side, and the first motor 46, second motor 47, and third motor 48 are disposed on relatively distal end members. Taking the base 42 and the first stage 43 as an example, when the first stage 43 moves relative to the base 42, the arm 41 moves together with the first stage 43, so the base 42 corresponds to the proximal end member and the first stage 43 corresponds to the distal end member. The first motor 46 is disposed on the first stage 43, which is the distal end member. Similarly, the second motor 47 is disposed on the second stage 44, and the third motor 48 is disposed on the third stage 45. The first motor 46, second motor 47, and third motor 48 may be disposed on relatively proximal end members. Specifically, in the relationship between the base 42 and the first stage 43, the first motor 46 may be disposed on the base 42. With respect to the relationship between the first stage 43 and the second stage 44, the second motor 47 may be disposed on the first stage 43. With respect to the relationship between the second stage 44 and the third stage 45, the third motor 48 may be disposed on the second stage 44. When the first motor 46, the second motor 47, and the third motor 48 are disposed on members relatively closer to the base end, the first motor 46, the second motor 47, and the third motor 48 can operate a ball screw drive mechanism or a belt drive mechanism to move the first stage 43, the second stage 44, and the third stage 45.

[0036] When the body 11 is transported, the locator 4 activates the first stage 43, the second stage 44, and the third stage 45 to connect the pin 41a to the body 11. With the pin 41a connected to the body 11, the locator 4 moves the third stage 45 upward. The arm 41 of the locator 4 supports the body 11 from below while lifting it above the carriage 14. With the body 11 supported, the locator 4 activates the first stage 43, the second stage 44, and the third stage 45 to align the body 11. The system controller 16 calculates the amount of movement of each stage 43, 44, and 45 based on images acquired by the external camera 191 and calculation results of the monitoring device 30, which will be described later.

[0037] The value of the current supplied to the third motor 48 is acquired by the current sensor 49. The detected current value acquired by the current sensor 49 is sent to the monitoring device 30, which will be described later. When the third motor 48 is a DC motor, the detected current value is the magnitude of the current itself supplied to the third motor 48. When the third motor 48 is an AC motor, the detected current value is the magnitude of the amplitude of the current supplied to the third motor 48. Note that when the third motor 48 is an AC motor, the current sensor 49 may acquire the current value of the q-axis current.

[0038] (Monitoring system) The third motors 48 of the four locators 4 are monitored by the monitoring system 3. The monitoring system 3 monitors the load on the third motors 48. As shown in FIG. 5 , the monitoring system 3 includes a monitoring device 30 and a display device 34. Note that the display device 34 is not an essential component of the monitoring system 3.

[0039] The monitoring device 30 has a processor 31, a memory 32, and an I / O bus 33. The processor 31 includes one or more CPUs. The processor 31 is composed of one or more chips. The memory 32 is composed of RAM (Random Access Memory) and ROM (Read Only Memory). The memory 32 is, for example, a non-volatile memory. The I / O bus 33 is an input / output bus that inputs and outputs electrical signals to and from the processor 31.

[0040] The monitoring device 30 is electrically connected to the current sensors 49 of the first locator 4a, the second locator 4b, the third locator 4c, and the fourth locator 4d. The monitoring device 30 acquires detected current values ​​from the current sensors 49 of the first locator 4a, the second locator 4b, the third locator 4c, and the fourth locator 4d via the I / O bus 33. The monitoring device 30 is electrically connected to the system controller 16. The monitoring device 30 acquires the detection results of the sensors 20 via the system controller 16.

[0041] The processor 31 calculates a comparison value for each locator 4 by comparing the detected current value with a representative value. The representative value has the same units or dimensions as the detected current value and is either the detected current value itself or a parameter calculated from the detected current value. For example, the representative value is the current value supplied to the third motor 48 when a master workpiece is aligned by the locator 4 on the same production line. Specifically, the representative value is the detected current value acquired by the current sensor 49 when the master workpiece is supported from below by the arm 41 after alignment of the master workpiece is complete. The state in which alignment is complete is when the master workpiece is parallel to the conveying path 15. In this case, the representative value corresponds to the reference current value when the locator 4 aligns the workpiece. The representative value is set for each locator 4. The memory 32 stores the current value for each locator 4 as the representative value.

[0042] The processor 31 calculates the ratio between the detected current value and the representative value as the comparison value. Comparison value = (detected current value / representative value) x 100 The comparison value is calculated using the formula: For example, when the detected current value is the same as the representative value, processor 31 sets the comparison value to 100%, and when the detected current value is half the representative value, the comparison value is 50%. When the detected current value is greater than the representative value, processor 31 calculates a value greater than 100%, such as 120%, as the comparison value. Processor 31 monitors the comparison values ​​across all four locators 4.

[0043] The detected current value represents the load on the third motor 48. The comparison value reflects changes in the load on the third motor 48. The processor 31 calculates the comparison value for each locator 4, and the monitoring system 3 monitors the load balance across all four locators 4.

[0044] As shown in FIG. 6 , display device 34 displays the comparison values ​​calculated by monitoring device 30 for each locator 4 in the same arrangement as the locators 4 when work area 13 is viewed from above. Specifically, when viewed from the front, the display screen of display device 34 displays a first display area 34a in the upper left, a second display area 34b in the lower left, a third display area 34c in the upper right, and a fourth display area 34d in the lower right. First display area 34a displays the comparison value of first locator 4a, second display area 34b displays the comparison value of second locator 4b, third display area 34c displays the comparison value of third locator 4c, and fourth display area 34d displays the comparison value of fourth locator 4d. Display device 34 displays the comparison values ​​together with the names or identification numbers of locators 4.

[0045] The display device 34 changes the color of the display area depending on the magnitude of the comparison value. For example, the display device 34 displays green when the comparison value is equal to or greater than a first threshold value and less than a second threshold value that is greater than the first threshold value. The display device 34 displays yellow when the comparison value is less than the first threshold value. The display device 34 displays red when the comparison value is equal to or greater than the second threshold value. Note that these colors are merely examples, and other colors may be set. The first threshold value is not particularly limited, but is, for example, 90%. The second threshold value is not particularly limited, but is, for example, 110%.

[0046] The monitoring device 30 acquires the detected current value from the current sensor 49 at predetermined time intervals, and calculates a comparison value using the processor 31. The monitoring device 30 updates the display on the display device 34 every time it calculates a comparison value.

[0047] (flowchart) Next, the process of monitoring the comparison value by the monitoring system 3 will be described with reference to Figures 7 and 8. The process described below is stored as software in the form of a program in the memory 32 of the monitoring device 30. The processor 31 of the monitoring device 30 reads the program from the memory 32 and executes the process.

[0048] First, the process of acquiring the representative value will be described with reference to Fig. 7. The monitoring device 30 executes the flowchart in Fig. 7 when the robot system 1 is powered on and the transfer of the master workpiece is started. The monitoring device 30 also executes the flowchart in Fig. 7 when the specifications of the workpiece are changed and when the master workpiece is transferred again to check the operation of the locator 4.

[0049] In step S11, monitoring device 30 determines whether each locator 4 has started work. Monitoring device 30 determines whether each locator 4 is working based on a signal from sensor 20. If the result is YES, meaning that each locator 4 has started work, monitoring device 30 proceeds to step S12. If the result is NO, meaning that each locator 4 has not started work, monitoring device 30 ends the process.

[0050] In step S12, the monitoring device 30 determines whether or not the alignment of the master workpiece has been completed. The monitoring device 30 determines whether or not the alignment has been completed based on an image acquired by the external camera 191. The state in which the alignment has been completed is a state in which the master workpiece is parallel to the conveying path 15. If the result of the determination is YES, that is, the alignment of the master workpiece has been completed, the monitoring device 30 proceeds to step S13. If the result of the determination is NO, that is, the alignment of the master workpiece has not been completed, the monitoring device 30 returns to step S12.

[0051] In step S13, the monitoring device 30 acquires the detected current values ​​from the four current sensors 49 via the I / O bus 33.

[0052] Next, in step S14, monitoring device 30 stores the detected current value acquired in step S13 in memory 32 for each locator 4 as a representative value for each locator 4.

[0053] After step S14, the monitoring device 30 ends the process.

[0054] Next, the process of monitoring the comparison value by the monitoring device 30 will be described with reference to FIG.

[0055] First, in step S21, monitoring device 30 determines whether each locator 4 is working. Monitoring device 30 determines whether each locator 4 is working based on a signal from sensor 20. If the result is YES, meaning that each locator 4 is working, monitoring device 30 proceeds to step S22. If the result is NO, meaning that each locator 4 is not working, monitoring device 30 ends the process.

[0056] In step S22, the monitoring device 30 acquires the detected current values ​​from the four current sensors 49 via the I / O bus 33.

[0057] Next, in step S23, monitoring device 30 reads the representative value from memory 32. Processor 31 reads the representative value stored for each of the four locators 4.

[0058] Next, in step S24, monitoring device 30 compares the detected current value with the representative value and calculates a comparison value for each locator 4.

[0059] Next, in step S25, monitoring device 30 transmits a control signal to display device 34 to display the calculated comparison value for each locator 4.

[0060] After step S25, the monitoring device 30 returns to step S21. The monitoring device 30 continues to monitor the comparison value until the determination in step S21 becomes NO.

[0061] (Action and effect) The monitoring system 3 monitors the comparison value for the current value of the third motor 48 for each locator 4. The current value of the third motor 48 corresponds to the load on the third motor 48. The monitoring system 3 calculates the comparison value of the load for each locator 4 and monitors all of the locators 4, so that the cause of a change in the load on the third motor 48 can be easily clarified.

[0062] For example, as shown in FIG. 6, the comparison values ​​of the second locator 4b and the third locator 4c exceed the second threshold, while the comparison values ​​of the first locator 4a and the fourth locator 4c are equal to or less than the first threshold. In this case, the system controller 16 can infer that the change in load is due to the body 11 being tilted toward the second locator 4b and the third locator 4c rather than parallel to the conveying path 15. The monitoring device 30 transmits a signal indicating each current comparison value to the system controller 16. The system controller 16 may align the body 11 by controlling each locator 4 so that the comparison value of each locator 4 is equal to or greater than the first threshold and less than the second threshold. In other words, the monitoring device 30 can align the body 11 by monitoring the comparison values ​​of all the locators 4.

[0063] Because the body 11 is transported to the work area 13 by the AMR 6, the body 11 is likely to shift in position when it arrives at the work area 13. Furthermore, the external camera 191 can easily detect a shift in the position of the body 11 in the horizontal direction, but has difficulty detecting a shift in the position of the body 11 in the vertical direction. The monitoring system 3 can represent the shift in the position of the body 11 in the vertical direction as a change in the load on the third motor 48. The monitoring system 3 improves the accuracy of the alignment of the body 11.

[0064] For example, suppose that the comparison value of only the first locator 4a frequently exceeds the second threshold value even though the body 11 is parallel to the conveying path 15. In this case, the monitoring device 30 can estimate that the change in load is due to deterioration of the third motor 48 of the first locator 4a. In other words, by having the monitoring device 30 monitor the comparison values ​​of all the locators 4, the quality of the third motor 48 of each locator 4 can be controlled.

[0065] For example, suppose the comparison values ​​of the first locator 4a, the second locator 4b, and the third locator 4c are equal to or greater than the first threshold and less than the second threshold, while the comparison value of only the fourth locator 4d is less than the first threshold. In this case, this means that only the load on the fourth locator 4d is small. As described above, when the alignment of the body 11 is insufficient, not only is the load on some locators 4 small, but the load on other locators 4 increases. When the third motor 48 of the fourth locator 4d is deteriorated, the load increases. Therefore, the monitoring device 30 can infer that a change in the load on the fourth locator 4d indicates a problem with the body 11 itself, such as a poor shape of the body 11. In other words, by having the monitoring device 30 monitor the comparison values ​​of all locators 4, quality control of the body 11 can be performed.

[0066] The representative value is the current value supplied to the third motor 48 when the master workpiece is aligned. When the master workpiece is aligned, the load on the locator 4 can be considered an ideal load. Because the comparison value indicates a change from the ideal load, monitoring the comparison value of each locator 4 makes it easier to understand the cause of the change in load.

[0067] The arm 41 supports the body 11 from below, and the third motor 48 moves the arm 41 in the vertical direction. The monitoring device 30 acquires the current value when the arm 41 supports the body 11. The load on the third motor 48 is a load in the vertical direction, and reflects the weight of the body 11 at the support position, so it is likely to reflect the influence of the posture and quality of the body 11. The monitoring device 30 calculates a comparison value for the load on each third motor 48, making it easier to understand the cause of a change in the load.

[0068] The locator 4 supports the body 11 transported to the work area 13 by the AMR 6 while the robot 2 is working on the body 11. By monitoring the load on the entire locator 4 while the robot 2 is working, the monitoring system 3 is able to grasp changes in the posture of the body 11 during work. The monitoring system 3 improves the accuracy of aligning the body 11 while the robot 2 is working.

[0069] Monitoring device 30 further includes a display device 34 that displays the comparison values ​​calculated by processor 31 for each locator 4 in the same layout as the multiple locators 4. By looking at display device 34, the worker can immediately understand which locator 4 has a load that is too high, or conversely, which locator 4 has a load that is too low. This makes it easier for the worker to understand the cause of a change in load.

[0070] (Variation 1) The process of monitoring the comparison value differs in Modification 1. Specifically, in Modification 1, the representative value is the average value of the current value supplied to the third motor 48 when multiple bodies 11 of the same type are aligned. In particular, the representative value is the average value of the current value supplied to the third motor 48 when alignment of the body 11 in the front-rear and left-right directions is complete.

[0071] FIG. 9 shows a process of monitoring the comparison value by the monitoring device 30 according to the first modification.

[0072] First, in step S31, monitoring device 30 determines whether each locator 4 is working. Monitoring device 30 determines whether each locator 4 is working based on a signal from sensor 20. If the answer is YES, that is, each locator 4 is working, monitoring device 30 proceeds to step S32. If the answer is NO, that is, that each locator 4 is not working, monitoring device 30 ends the process.

[0073] In step S32, the monitoring device 30 acquires the detected current values ​​from the four current sensors 49 via the I / O bus 33.

[0074] Next, in step S33, monitoring device 30 reads the representative value from memory 32. Monitoring device 30 reads the representative value stored for each of the four locators 4.

[0075] Next, in step S34, monitoring device 30 compares the detected current value with the representative value and calculates a comparison value for each locator 4.

[0076] Next, in step S35, monitoring device 30 transmits a control signal to display device 34 to display the calculated comparison value for each locator 4.

[0077] Next, in step S36, the monitoring device 30 determines whether or not alignment of the body 11 has been completed. The monitoring device 30 determines whether or not alignment has been completed based on the image acquired by the external camera 191 and the calculated comparison value. The state in which alignment has been completed is a state in which the body 11 is parallel to the conveying path 15. If the result of the determination in step S36 is YES, meaning that alignment of the body 11 has been completed, the monitoring device 30 proceeds to step S37. If the result of the determination in step S36 is NO, meaning that alignment of the body 11 has not been completed, the monitoring device 30 returns to step S32.

[0078] In step S37, the monitoring device 30 acquires the detected current values ​​from the four current sensors 49 via the I / O bus 33.

[0079] Next, in step S38, the monitoring device 30 updates the representative value stored in the memory 32 based on the detected current value acquired in step S37. The representative value is the average value of the detected current values ​​acquired in step S37.

[0080] After step S38, the monitoring device 30 returns to step S31. The monitoring device 30 continues to monitor the comparison value until the determination in step S31 becomes NO.

[0081] In the first modification, the representative value reflects the current value supplied to the third motor 48 when the actual alignment of the body 11 is completed. By using the representative value of the first modification, changes in the posture and quality of the body 11 are easily reflected as changes in the load. This makes it easier for the worker to understand the cause of the change in the load.

[0082] (Variation 2) Modification 2 differs in the process of monitoring the comparison value. Specifically, in Modification 2, the representative value is one current value selected from current values ​​acquired by I / O bus 33 at the same timing. For example, when the current value of first locator 4a is selected as the representative value, the comparison value is the ratio of first locator 4a to the current value supplied to third motor 48. The specific locator for which the detected current value is set as the representative value is set in advance. The comparison value of the specific locator is always 100%. Note that "the same timing" does not have to be strictly simultaneous, but may be within a predetermined time period.

[0083] FIG. 10 shows a process of monitoring the comparison value by the system controller 16 according to the second modification.

[0084] First, in step S41, monitoring device 30 determines whether each locator 4 is working. Monitoring device 30 determines whether each locator 4 is working based on a signal from sensor 20. If the answer is YES, that is, each locator 4 is working, monitoring device 30 proceeds to step S42. If the answer is NO, that is, that each locator 4 is not working, monitoring device 30 ends the process.

[0085] In step S42, the monitoring device 30 acquires the detected current values ​​from the four current sensors 49 via the I / O bus 33.

[0086] Next, in step S43, monitoring device 30 sets the detected current value acquired from the specified locator as a representative value.

[0087] Next, in step S44, monitoring device 30 compares the detected current value with the representative value and calculates a comparison value for each locator 4.

[0088] Next, in step S45, monitoring device 30 transmits a control signal to display device 34 to display the calculated comparison value for each locator 4.

[0089] After step S45, the monitoring device 30 returns to step S41. The monitoring device 30 continues to monitor the comparison value until the determination in step S41 becomes NO.

[0090] In the second modification, the load on the third motor 48 is compared between the locators 4, so the deterioration state of the third motor 48 is easily reflected. For example, when the third motor 48 of a locator other than the specific locator is deteriorated, the comparison value of that locator becomes high, and it can be determined that the third motor 48 is deteriorated. On the other hand, when the third motor 48 of the specific locator is deteriorated, the comparison values ​​of the other locators become low, and it can be determined that the third motor 48 of the specific locator is deteriorated.

[0091] (Other variations) The above-described monitoring device 30 acquires the detected current value of current sensor 49. However, instead of the detected current value of current sensor 49, monitoring device 30 may acquire the value of the current supplied to third motor 48 by locator controller 18. In this case, current sensor 49 is not necessary.

[0092] The monitoring device 30 described above calculates the ratio of the detected current value to the representative value as the comparison value. However, the monitoring device 30 may calculate the rate of change of the detected current value to the representative value as the comparison value. In this case, the processor 31 of the monitoring device 30 calculates the rate of change of the detected current value to the representative value as the comparison value. Comparison value = {(detected current value - representative value) / representative value} x 100 The comparison value is calculated by the following formula: When the detected current value is smaller than the representative value, the display device 34 displays a minus sign before the numerical value.

[0093] The monitoring system 3 described above monitors the load on the third motor 48. The monitoring target of the monitoring system 3 does not necessarily have to be the third motor 48. For example, the monitoring system 3 may monitor the load on the first motor 46 and the load on the second motor 47. The display device 34 may display the comparison value for the first motor 46 and the comparison value for the second motor 47 instead of or in addition to the comparison value for the third motor 48.

[0094] The monitoring device 30 described above was separate from the system controller 16. However, the monitoring device 30 may be part of the system controller 16. The display device 34 may also be part of the system controller 16. The monitoring device 30 may also be incorporated into the locator controller 18.

[0095] In the robot system 1 described above, the locator 4 aligns the position of the body 11 in a horizontal plane. The AMR 6 may align the position of the body 11 in a horizontal plane in the work area 13. Even in this case, by having the monitoring system 3 monitor the load balance across the locator 4, it becomes easier to determine whether the cause of a change in load is the quality of the body 11 or deterioration of the third motor 48.

[0096] It should be noted that the work performed by the robot system 1 equipped with the monitoring system 3 disclosed herein in the manufacturing line 10 is not limited to welding. Also, the workpiece that the robot system 1 works on is not limited to the automobile body 11. Furthermore, the monitoring system 3 is not limited to application to the automobile manufacturing line 10.

[0097] 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 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.

[0098] (Aspect) The above embodiments are specific examples of the following aspects.

[0099] (Aspect 1) a plurality of locators (4a, 4b, 4c, 4d) each having an arm (41) moved by a motor (48) and for aligning the workpiece (11) transported to the working area (13) at different positions from each other; a monitoring device (30) that calculates a comparison value for each of the locators (4a, 4b, 4c, 4d) by comparing the current value supplied to the motor (48) with a representative value that is set for each of the locators (4a, 4b, 4c, 4d) and is associated with the current value.

[0100] The monitoring system (3) calculates a load comparison value for each locator (4a, 4b, 4c, 4d) and monitors the load balance across all locators (4a, 4b, 4c, 4d). The monitoring system (3) allows an operator to easily identify the cause of a change in the load on the motor (48).

[0101] (Aspect 2) The monitoring system (3) according to aspect 1, wherein the representative value is the current value when the master workpiece is aligned.

[0102] With the master workpiece aligned, the load on the locator 4 can be considered the ideal load. The comparison value can indicate any variation from the ideal load, making it easier for the operator to understand the cause of the load variation.

[0103] (Aspect 3) The monitoring system (3) according to aspect 1, wherein the representative value is an average value of the current values ​​when a plurality of the workpieces (11) of the same type are aligned.

[0104] Changes in the posture and quality of the workpiece (11) are more easily reflected as changes in the load, making it easier for the worker to understand the cause of the load change.

[0105] (Aspect 4) The monitoring system (3) according to aspect 1, wherein the representative value is one current value selected from the current values ​​supplied at the same timing.

[0106] Since the loads of the motors 48 are compared between the locators 4a, 4b, 4c, and 4d, the deterioration state of the motors 48 is more easily reflected, making it easier for the operator to understand the cause of changes in the load.

[0107] (Aspect 5) The arm (41) supports the work (11) from below, The motor (48) moves the arm (41) in the vertical direction, The monitoring system (3) according to any one of the first to fourth aspects, wherein the monitoring device (30) acquires the current value when the arm (41) supports the workpiece (11).

[0108] The load on the motor 48 reflects the weight of the workpiece 11 at the support position, and is therefore likely to reflect the influence of the posture and quality of the workpiece 11. The monitoring device 30 calculates a comparison value for the load on each motor 48, making it easier for the worker to understand the cause of a change in the load.

[0109] (Aspect 6) The monitoring system (3) according to aspect 5, wherein the locators (4a, 4b, 4c, 4d) support the workpiece (11) transported to the work area (13) by a transport vehicle (6) while the robot (2) is working on the workpiece (11).

[0110] The load balance of the entire locators (4a, 4b, 4c, 4d) can be monitored while the robot (2) is working. If the workpiece (11) is not sufficiently supported and the posture of the workpiece (11) changes while the robot (2) is working, the monitoring system (3) can detect this. The monitoring system (3) improves the accuracy of aligning the workpiece (11) while the robot (2) is working.

[0111] (Aspect 7) The monitoring system (3) according to any one of aspects 1 to 6, further comprising a display device (34) that displays the comparison values ​​calculated by the monitoring device (30) for each of the plurality of locators (4a, 4b, 4c, 4d) in the same arrangement as the arrangement of the locators (4a, 4b, 4c, 4d).

[0112] By looking at the display device 34, the worker can immediately understand which locator (4a, 4b, 4c, 4d) has a load that is too high, or conversely, which locator (4a, 4b, 4c, 4d) has a load that is too low, making it easier for the worker to understand the cause of the change in load. [Explanation of symbols]

[0113] 2. Robot 3. Surveillance System 4 Locators 6 AMR (transport vehicle) 11 Body (work) 13 Work Area 30 Monitoring equipment 34 Display device 41 Arm 48 Third Motor

Claims

1. a plurality of locators each having an arm moved by a motor and aligning a workpiece transported to a work area at a different position from each other; a monitoring device that calculates a comparison value for each locator by comparing the current value supplied to the motor with a representative value that is set for each locator and is associated with the current value.

2. 2. The monitoring system according to claim 1, A monitoring system in which the representative value is the current value when the master workpiece is aligned.

3. 2. The monitoring system according to claim 1, A monitoring system in which the representative value is an average value of the current value when multiple workpieces of the same type are aligned.

4. 2. The monitoring system according to claim 1, A monitoring system in which the representative value is one current value selected from the current values ​​supplied at the same timing.

5. The monitoring system according to any one of claims 1 to 4, The arm supports the workpiece from below, The motor moves the arm in a vertical direction, The monitoring device is a monitoring system that acquires the current value when the arm supports the workpiece.

6. 6. The monitoring system according to claim 5, The locator is a monitoring system that supports the workpiece transported to the work area by a transport vehicle while a robot is working on the workpiece.

7. The monitoring system according to any one of claims 1 to 4, The monitoring system further comprises a display device that displays the comparison values ​​calculated by the monitoring device for each of the locators in the same arrangement as the arrangement of the plurality of locators.

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