Work monitoring system

Abstract

This work monitoring system monitors a robot arm that repeatedly performs work for rotating a workpiece at each of one or more work positions. The work monitoring system comprises a display device and a processor. The processor is configured to store, in a storage unit, a load applied to the robot arm by the work for each of the one or more work positions. The processor can display, on the display device, a tendency of a change in the load of the work that is repeatedly performed.

Description

Work Monitoring System

[0001] The present disclosure relates to a work monitoring system.

[0002] Conventionally, there has been known an abnormality detection method for screw tightening work performed by a robot arm having a screw tightening tool attached to its distal end via a force sensor. In this method, a control device monitors torque and the like applied to the screw tightening tool while acquiring the axial position of the screw tightening tool that moves in the axial direction in accordance with the progress of the screw tightening work. Then, in this method, the control device determines the type of abnormality according to the axial position of the screw tightening tool when an abnormality occurs in the torque. See, for example, Patent Document 1.

[0003] Japanese Unexamined Patent Application Publication No. 2012-171071

[0004] As described above, the conventional abnormality detection method only monitors the process of tightening a single screw and determines the type of abnormality based on the progress degree of the process when an abnormality occurs. On the other hand, when an arm repeatedly performs a work of rotating a workpiece such as screw tightening work, unexpected failures, abnormalities, etc. may occur in the arm due to repeated loads applied to joints. It is desired to ensure the operation of the arm that can be used stably over a long period of time.

[0005] A first aspect of the present disclosure provides a work monitoring system that monitors a robot arm that repeatedly performs work of rotating a workpiece at each of one or more work positions, comprising a display device and a processor, wherein the processor is configured to store, for each of the one or more work positions, a load applied to the robot arm by the work in a storage unit, and the processor is capable of displaying a tendency of a change in the load of the repeatedly performed work on the display device.

[0006] This is a schematic diagram of a work monitoring system according to one embodiment. This is a block diagram of the control device for the arm of the work monitoring system according to this embodiment. This is a block diagram of the work monitoring system according to this embodiment. This is a flowchart showing an example of processing by the work monitoring system according to this embodiment. This is an example of load trend data obtained by the work monitoring system according to this embodiment. This is an example of work result trend data obtained by the work monitoring system according to this embodiment. This is an example of load and work result trend data obtained by the work monitoring system according to this embodiment. This is an example of load and work result trend data obtained by the work monitoring system according to this embodiment. This is an example of load and work result trend data obtained by the work monitoring system according to this embodiment. This is an example of load and work result trend data obtained by the work monitoring system according to this embodiment.

[0007] A work monitoring system 1 of the first embodiment will be described below with reference to the drawings. The work monitoring system 1 of this embodiment has one or more robots (machines) 10. In this embodiment, each robot 10 is a vertical articulated robot and is equipped with an articulated arm 20 as shown in Figure 1. The arm 20 is equipped with a control device 30, and in this embodiment, a tool 40 is attached to the tip of the arm 20.

[0008] The arm 20 comprises an arm base 11, a plurality of arm members 21, 22, 23, 24, 25, 26, and a plurality of joints. Each of the multiple joints is rotatable around axes J1 to J6 shown in Figure 1. The arm 20 also includes a plurality of motors 27, such as servo motors, to drive each of the multiple joints (Figure 2). Various types of motors, such as rotary motors and linear motors, can be used as each motor 27. Each motor 27 has an operating position detection device for detecting its operating position and operating speed, and the operating position detection device is an encoder as an example. The detected value of the operating position detection device is transmitted to the control device 30. The number of arm members and joints may be 5 or less, or 7 or more.

[0009] The arm 20 is not limited to any particular type. The arm 20 may be the arm of a horizontal articulated robot, the arm of a multi-link robot, etc. Furthermore, the arm 20 may be supported by a moving device such as a linear guide, an AGV (Automatic Guided Vehicle), a vehicle, a walking robot, etc.

[0010] In this embodiment, the arm 20 is a robotic arm for a collaborative robot. The collaborative robot has a function to detect contact between the arm 20 and people, objects, etc., using known sensors such as force sensors, contact sensors, and vision sensors, and to safely stop the arm 20 according to the detection result. In addition, the collaborative robot may also have a function to decelerate or stop the arm 20 immediately before contact with people, objects, etc.

[0011] The arm 20 of this embodiment has known force sensors 28, such as torque sensors, at each of its six joints, including the joint between the mounting surface and the arm member 21, and the joint between the arm member 21 and the arm member 22. Each force sensor 28 detects the force, such as torque, applied to each joint.

[0012] Alternatively, a known 6-axis force sensor may be provided between the mounting surface and the arm member 21, or a tactile sensor may be provided on the surface of the arm member 21 to detect the contact force when it comes into contact with an object, or other sensors may be provided. In these cases, the control device 30 calculates the force, such as torque, applied to each joint using the detection results of the sensors, data on the configuration of the arm 20, data on the configuration of the tool 40, data on the posture of the arm 20, etc. Examples of data on the configuration of the arm 20 and tool 40 are calculation models of the arm 20 and tool 40. In some cases, the force sensor 28 may be provided only at one or more joints on the tip side of the arm 20, and the force, such as torque, applied to the said one or more joints on the tip side may be detected. The detection value of the force sensor 28 is transmitted to the control device 30.

[0013] In this embodiment, as shown in Figure 1, the tool 40 is called a nut runner and performs the operation of rotating a workpiece W, which is a nut. The tool 40 has a drive device 41 which has a motor or the like built in, a rotating shaft 42 which is rotated by the drive device 41, and a tip member 43 which is detachably attached to the rotating shaft 42. An engagement hole is provided at the tip of the tip member 43, and the engagement hole has a shape that engages with the outer circumferential surface of the workpiece W around the central axis of the workpiece W. In this embodiment, the tool 40 is attached to the tip of the arm 20 via a fixing member 44, but the tool 40 may also be attached to other parts of the arm 20.

[0014] In this embodiment, the workpiece W is accommodated in the engagement hole of the tip member 43 of the tool 40 by the movement of the arm 20, and when the tip member 43 is rotated by the drive device 41, the workpiece W is tightened into a mating part such as a male screw.

[0015] As shown in Figure 2, the control device 30 for controlling the arm 20 includes a processor 31 such as a CPU, a microcomputer processor, or a PLC processor, and a known display device 32 such as a liquid crystal display. The control device 30 also includes a memory unit 33 having non-volatile storage, RAM, etc., and examples of non-volatile storage include hard disks, flash memory, ROM, etc. In some cases, the CPU, microcomputer, PLC, or storage device of an external computer may function as part of the memory unit 33. The control device 30 also includes an input device 34 which includes one of the following computers: a keyboard, touch panel, control panel, teaching control panel, tablet computer, etc., and a transmitting / receiving unit 35 for transmitting and receiving signals. The control device 30 also includes a servo controller 36 connected to each motor 27 and a servo controller 37 connected to the drive unit 41.

[0016] The teaching control panel is a portable control panel called a teach pendant. When the input device 34 is a computer such as a control panel, teaching control panel, or tablet computer, the input device 34 is equipped with a known display device 34A such as a liquid crystal display, and the processor of the input device 34 may function as part or all of the processor 31. The input device 34 and the transmitting / receiving unit 35 function as input units. The storage unit 33 stores an operation program 33A, and the processor 31 controls each motor 27 and drive unit 41 based on the operation program 33A and operation signals from the input device 34.

[0017] In this embodiment, as shown in Figure 1, a known two-dimensional or three-dimensional visual sensor 50 is provided, the working range of the arm 20 being within its detection range. In Figure 1, the visual sensor 50 is fixed to a frame other than the arm 20, but the visual sensor 50 may be attached to the arm 20. The visual sensor 50 may be another type of sensor, such as a three-dimensional distance sensor. In one example, the operation program 33A is set based on the coordinate system 20A of the arm 20, and the coordinate system of the visual sensor 50 and the coordinate system 20A are associated within the control device 30.

[0018] In this embodiment, as shown in Figure 1, the arm 20 rotates and clamps the workpiece W sequentially at multiple working positions 101, 102, and 103 based on the operation program 33A, and the control device 30 controls each motor 27 and drive device 41 for this operation. There may also be only one working position. In this embodiment, the detection results of the visual sensor 50 and the detection values ​​of each force sensor 28 are used for this operation, but these may not always be used.

[0019] As shown in Figure 3, the work monitoring system 1 includes a processor 51 such as a CPU, a microcomputer processor, or a PLC processor, a known display device 52 such as a liquid crystal display device, and a memory unit 53 having non-volatile storage, RAM, etc. The work monitoring system 1 may consist of one computer or multiple computers. Furthermore, the work monitoring system 1 may have one or more display devices 52, and the display devices 52 may include display devices of one or more computers wirelessly connected to the work monitoring system 1.

[0020] Examples of non-volatile storage include hard disks, flash memory, and ROM. In some cases, a CPU, microcomputer, PLC, or external computer storage device may function as part of the storage unit 53. The work monitoring system 1 also includes an input device 54, which may include a keyboard, touch panel, control panel, or tablet computer, and a transmitting / receiving unit 55 for sending and receiving signals.

[0021] An external computer capable of communicating with the work monitoring system 1 may also function as input device 54 and display device 52. The external computer includes a control unit 30 and an input device 34, which may be a teaching control panel or a tablet computer. The input device 54 may be equipped with a known display device 54A, such as a liquid crystal display, and the processor of the input device 54 or the processor 31 of the control unit 30 may function as part or all of the processor 51. The storage unit 33 of the control unit 30 may also function as part or all of the storage unit 53. The input device 54 and the transmitting / receiving unit 55 function as input units. The work monitoring system 1 can communicate with the control unit 30 by wire or wireless.

[0022] The storage unit 53 stores the system program, which is responsible for the basic functions of the work monitoring system 1. The storage unit 53 stores the load result monitoring program 53A and the work abnormality monitoring program 53B. An example of the processing performed by the processor 51 based on the load result monitoring program 53A and the work abnormality monitoring program 53B will be explained below with reference to the flowchart in Figure 4.

[0023] First, the processor 51 receives the load values ​​applied to each joint of the arm 20 from each robot 10 based on the load result monitoring program 53A (step S1-1).

[0024] Here, the control device 30 of each robot 10 transmits the detected load ratio (load) values ​​detected by each force sensor 28 to the work monitoring system 1 as load data applied to each joint, based on the force data transmission program 33B (Figure 2). The load ratio not only indicates the ratio of the torque generated with the rated torque of the motor 27 of each joint set to 100%, but also calculates the force and moment applied to the TCP (tool center point) set at the tip of the tool 40, etc., based on the robot coordinates from the generated torque, and comprehensively evaluates these loads. In some cases, load data for each joint calculated based on the detection results of the 6-axis force sensor may be transmitted instead of the detected values ​​of each force sensor 28. In this embodiment, the load data for each joint is the load data assuming that the load is zero when the arm 20 to which the tool 40 is attached is in an unloaded state and in a predetermined posture. The load data for each joint may also be the load data assuming that the load is zero when the force sensor 28 is in an unloaded state. Other values, such as the detection values ​​from each force sensor 28 or other values, may be transmitted to the work monitoring system 1 as load data for each joint.

[0025] In this embodiment, the load data is the maximum value detected by the force sensor 28 during a single operation in which the tool 40 rotates the workpiece W and completes the tightening. That is, each of the six maximum values ​​detected by the six force sensors 28 during that single operation is transmitted to the work monitoring system 1. Instead of the maximum value, a value related to the maximum value or a value with other characteristics may be used. Examples of values ​​related to the maximum value include the value detected by the force sensor 28 at the timing when the maximum value is expected to occur, or the average value of the values ​​detected by the force sensor 28 within the time range in which the maximum value is expected to occur. An example of a value with characteristics is the value after a predetermined time has elapsed since the tool 40 started rotating the workpiece. In this embodiment, the data sent to the work monitoring system 1 for each operation is simple, and this configuration contributes to reducing the information processing load and data communication volume in order to achieve the effects described later.

[0026] Furthermore, the processor 31 adds additional information related to each of the load data for each joint, and the work monitoring system 1 acquires the load data for each joint, including the additional information. The additional information includes at least one of the following: machine identification information indicating which arm 20 it is, joint identification information indicating which joint it is, time information indicating the time of work, work position identification information, and posture information relating to the posture of the arm 20. The work position identification information is information indicating which of the work positions 101, 102, or 103 it is. In this embodiment, the additional information includes machine identification information, joint identification information, time information, and work position identification information. The time information is information that indicates the detection order of multiple load data obtained in the repeated work. The additional information only needs to be information that can link the result data and load data, as described later.

[0027] Next, the processor 51, based on the load result monitoring program 53A, stores load data for each joint of each arm 20 in the storage unit 53 (step S1-2). The load data for each joint stored in the storage unit 53 is associated with additional information.

[0028] Furthermore, the processor 51 creates trend data for each joint and work position for each arm 20 based on the load result monitoring program 53A (step S1-3). Specifically, in this embodiment, trend data is created for each joint and each work position by arranging multiple load data obtained from the repeated work in the order in which they were obtained. The trend data may be a graph, table, etc., with one axis being the time axis.

[0029] Figure 5 shows an example of graphing load trend data. In Figure 5, the load data for each joint at the working position 101 is graphed for the furthest joint (sixth joint), the second joint from the tip (fifth joint), and the third joint from the tip (fourth joint) of a certain arm 20. In Figure 5, load trend data for other working positions 102 and 103 may also be displayed simultaneously, and load data for other joints may be graphed in the same way in Figure 5. In this embodiment, the joint between arm member 21 and arm member 22 is referred to as the first joint, and therefore the furthest joint is referred to as the sixth joint, and so on.

[0030] Next, the processor 51 determines, based on the load result monitoring program 53A, whether or not there is a noteworthy change in the trend data of each joint (step S1-4). A noteworthy change may indicate an abnormality. For example, as shown in Figure 5, if the trend data of the fifth joint exceeds the monitoring threshold, it is determined that there is a noteworthy change in the fifth joint. In Figure 5, the monitoring threshold for the fifth joint is shown by a dashed line, but the monitoring thresholds for other joints may be shown similarly. Note that each joint of the arm 20 has an allowable value for the load rate, such as the maximum allowable load, and when the force sensor 28 of each joint detects a load rate that exceeds the allowable value of the force, the processor 31 stops the arm 20. The monitoring threshold for each joint is set to a value smaller than the allowable value of the load rate.

[0031] In another example, as shown in Figure 5, the processor 51 determines that there is a noteworthy change in the fifth joint when, for example, the slope of the trend data for the fifth joint becomes greater than the change monitoring threshold. In Figure 5, the change monitoring threshold for the fifth joint is shown by a dashed line. In yet another example, the processor 51 determines that there is a noteworthy change in the fifth joint when, for example, the trend data for the fifth joint deviates by a predetermined amount from reference values ​​such as the initial value, the load value from a predetermined number of times, or the average of the load values ​​from a predetermined number of times.

[0032] Based on the load result monitoring program 53A, if the processor 51 determines in step S1-4 that there is a change of note, it displays the trend data on the display devices 52 and 54A in the form of a graph or table, for example, as shown in Figure 5 (step S1-5). The processor 51 also performs a point of interest display to indicate the part where a change of note has been determined. The point of interest display may be done by enclosing the area with a rectangle or other line of a different, conspicuous color (such as red), showing an approximation line of the slope of the part where a change of note has been determined to be noteworthy, as shown in Figure 5, or changing the color of the part in question from the other parts. The point of interest display may also be done by displaying a diagram, image, etc. pointing to the part in question, or by highlighting the part in question.

[0033] By viewing the display devices 52 and 54A, the user can recognize the trend of changes in the load on each joint, and can also recognize joints that the work monitoring system 1 has determined to have a noteworthy change. Obtaining information on the trend of changes in the load on each joint is useful for the user to plan maintenance on the arm 20, make decisions on appropriate actions, etc. For example, the change trend information regarding the fifth joint mentioned above is useful for deciding to accelerate the maintenance timing, deciding to change the arm 20 to another arm, setting changes in the posture of the arm 20 during the work, etc.

[0034] Next, the processor 51 receives result data for each of the repeated operations from the control devices 30 of each arm 20 based on the operation abnormality monitoring program 53B (step S1-6).

[0035] In this embodiment, the control device 30 of each robot 10 transmits the result data of each of the repeated tasks to the work monitoring system 1 based on the result data transmission program 33C (Figure 2).

[0036] An example of result data is force data applied to tool 40. Examples of force data include torque data detected by a torque sensor on tool 40, such as maximum value data, data relating to the maximum value, torque data with other characteristics, and torque data that changes over time. Alternatively, the torque data may be obtained by calculation using the detected value of the force sensor 28 on arm 20 and model data of arm 20. Other examples of result data include rotation angle data of tool 40 during the operation and rotation speed data of tool 40 during the operation. The processor 31 can obtain rotation angle data and rotation speed data based on the detected value of an encoder on tool 40, information on the current supplied to tool 40 for its rotation, etc. The information on the current may also be result data.

[0037] Another example of the result data is the distance the tool 40 travels in the axial direction along its rotation axis during the operation. For example, during the operation, the processor 31 performs force control to maintain the state in which the bottom of the engagement hole of the tip member 43 of the tool 40 is in contact with the workpiece W in the axial direction, and the detected value of the force sensor 28 is used for this force control. In this force control, when the workpiece W rotated by the tool 40 moves in the axial direction, the processor 31 controls the arm 20 to make the tool 40 follow the movement. Therefore, the processor 31 can obtain the distance the tool 40 travels in the axial direction during the operation of rotating and tightening the workpiece W with the tool 40 as distance data.

[0038] Furthermore, the processor 31 adds additional information related to each result data, and the work monitoring system 1 acquires the result data including the additional information. The additional information includes at least one of the following: machine identification information indicating which arm 20 or robot 10 it is, time information indicating when the work is performed, work position identification information indicating which of the work positions 101, 102, and 103 it is, and posture information relating to the posture of the arm 20. In this embodiment, the additional information includes machine identification information, time information, and work position identification information. The time information is information that indicates the detection order of multiple result data obtained in the repeatedly performed work, and / or information that indicates the corresponding load data. In other words, the processor 31 transmits the data in such a way that the result data can be associated with each of the load data. The additional information only needs to be information that can link the result data with the load data.

[0039] The processor 31 transmits one or more of the above-mentioned result data to the work monitoring system 1. Based on the work abnormality monitoring program 53B, the processor 51 stores the result data for each arm 20 of the robot 10 in the storage unit 53 (step S1-7). The result data stored in the storage unit 53 is associated with additional information. Each result data corresponds to a plurality (six in this embodiment) of the load data obtained during the operation of that result data. Therefore, in a preferred embodiment of this model, each result data is associated with a plurality of load data and stored in the storage unit 53.

[0040] Next, the processor 51, based on the work abnormality monitoring program 53B, creates work result trend data for each work position for each arm 20, for example, as shown in Figure 6 (step S1-8). Specifically, in this embodiment, the processor 51 creates work result trend data for each work position by arranging multiple result data obtained in the repeatedly performed work in the order in which they were obtained. The work result trend data may be a graph, table, etc., with one axis being the time axis. Figure 6 shows a graph of the result data at a work position 101 of a certain arm 20.

[0041] Next, the processor 51 determines whether or not there is an abnormality in each work result trend data based on the work abnormality monitoring program 53B (step S1-9). In one example, as shown in Figure 6, the work result trend data is torque trend data, and if the torque exceeds the torque monitoring threshold, it is determined that there is an abnormality in the work. In Figure 6, the result monitoring threshold is shown by a dashed line. In many cases, an allowable torque is set for the tool 40 itself. In this case, if a torque exceeding the allowable torque is detected based on the torque sensor of the tool 40, the current value of the tool 40, etc., the processor 31 stops the arm 20. For each work position, the torque monitoring threshold is set to a value smaller than the allowable torque. In addition, a configuration may be adopted in which the processor 51 determines that there is an abnormality when the result data exceeds a predetermined threshold in step S1-9.

[0042] In another example, if the slope of the trend in the torque change, as seen in the torque trend data shown in Figure 6, exceeds the result change monitoring threshold, it is determined that there is an abnormality in the operation. In Figure 6, the result change monitoring threshold is shown by a dashed line. In yet another example, if the torque trend data shown in Figure 6 deviates by a predetermined amount from reference values ​​such as the initial value, the torque a predetermined number of times ago, or the average value of the torque a predetermined number of times ago, it is determined that there is an abnormality in the operation. The slope can be obtained, for example, as the slope of an arbitrary range of an approximate straight line or approximate curve obtained from the data by a known method. Step S1-4 is similar. The slope can also be obtained by other methods.

[0043] Based on the work abnormality monitoring program 53B, when it is determined that there is an abnormality in step S1-9, the processor 51 causes the display devices 52 and 54A to display work result trend data (step S1-10). The work result trend data is displayed, for example, in the form of a graph or a table as shown in FIG. 6 or FIG. 7. In FIG. 7, the work result trend data is displayed together with the trend data. Further, in FIG. 7, each result data of the work result trend data is displayed so as to correspond to a plurality of load data related to the result. The user can change the work position to be displayed using the input device 54, and can change the joint for which the change trend data is displayed. When a certain joint is important, the configuration may be such that change trend data is displayed for a single joint.

[0044] Note that there are also cases where the processor 51 transmits data for the display in steps S1-5 and S1-10 to the control device 30, and the processor 31 of the control device 30 performs the display in steps S1-5 and S1-10 using the display devices 32, 34A, etc. In this case, the processor 31 also functions as a processor of the work monitoring system 1.

[0045] The processor 51 also performs attention position display indicating a portion determined to have an abnormality, for example, as shown in FIGS. 6 and 7. Examples of the attention position display include showing an approximate line of the slope of the relevant portion determined to have an abnormality as in FIGS. 6 and 7, changing the color of the relevant portion from that of other portions, displaying a diagram, an image or the like pointing to the relevant portion, highlighting the relevant portion, and the like.

[0046] By looking at the display devices 52 and 54A, the user can recognize the trend of work results at each work position, and can also recognize the work result determined to have an abnormality by the work monitoring system 1. Note that such abnormalities may include not only abnormalities that must be improved immediately, but also minor abnormalities that only need to be improved within a predetermined period. Examples of minor abnormalities include a case where the torque is slightly higher than the average, but remains at a value lower than the result monitoring threshold.

[0047] As described above, by looking at the display devices 52 and 54A, the user can recognize that there is an abnormality in the tendency of work results or that the work result itself is abnormal, and can also recognize the corresponding tendency of changes in the load on each joint. Being able to recognize the two in association with each other in this way is useful not only for the maintenance plan of the arm 20 and the determination of corresponding measures, but also for discovering the possibility that the load applied to the arm 20 is unnecessarily increasing. In addition, being able to recognize the two in association with each other may be useful for resetting the operation of the arm 20 and resetting the layout including the arrangement positions of the arm 20 and the work W depending on the situation. Furthermore, being able to recognize the two in association with each other may be useful for the maintenance plan of the tool 40, determining countermeasures for the tool 40, estimating the tightening quality of the work W after work, etc. depending on the situation.

[0048] It should be noted that, instead of the tendency of work results, work result information may be displayed on the display devices 52 and 54A together with the tendency data of load changes. The work result information is, for example, information indicating that the tightening torque is large, information indicating that the rotation angle during tightening, the rotation speed, etc. are large. In this case, the user cannot recognize the tendency of work results. However, depending on the situation, such display may also be useful for the user to formulate a maintenance plan for the tool 40, determine countermeasures for the tool 40, and estimate the tightening quality of the work W after work.

[0049] For example, as shown in Fig. 7, when the work result tendency data (torque) tends to increase, and the load applied to the fifth joint also tends to increase, adjusting the force that pushes the tip member 43 toward the work W during the force control may be an improvement. Such resetting of the operation of the arm 20 can contribute to reducing the maintenance frequency of the arm 20 and reducing failures when the increasing tendency in the work result tendency data (torque) occurs frequently.

[0050] Figure 7 shows trend data for the work result (torque), and as shown in Figure 7, there are cases where a gradual increase in torque can be observed. The processor 51 determines that the torque is increasing when, for example, the slope exceeds the upper result change monitoring threshold shown in Figure 7. This situation may occur, for example, when the frictional resistance between the workpiece W and the mating part to which the workpiece W is tightened decreases. This frictional resistance may be influenced by the amount and / or quality of oil, anti-threading agent, etc. applied to the workpiece W and the mating part, the dimensions of the workpiece W and the mating part, etc. Other influencing factors may also exist.

[0051] At this time, when the trend of changes in the load on each joint is displayed on the display devices 52 and 54A, the user can find out whether or not there is an unnecessary increase in the load applied to each joint in response to the changes in the work result trend data. If there is no such increase in load trend in any joint, and the above trend is only observed in the work result trend data, the user can decide that no urgent action is necessary, which contributes to efficiency.

[0052] For example, when a large amount of oil is applied to the workpiece W, the force applied to the fifth joint may increase in relation to force control, as described above, or the force applied to the sixth joint, fourth joint, etc., may increase in relation to the control of the rotation of the tool 40. In such cases, the user can decide to take measures such as controlling the amount of oil, which can contribute to reducing the frequency of maintenance and malfunctions of the arm 20.

[0053] Figure 8 shows trend data for the work result (torque), and as shown in Figure 8, there are cases where a gradual decrease in torque can be observed. The processor 51 determines that the torque is decreasing when, for example, the slope exceeds the lower result change monitoring threshold shown in Figure 8. This determination may also be made when the lower result monitoring threshold is exceeded. For example, the ease of relative movement between the workpiece W and the mating part to which the workpiece W is tightened may influence this phenomenon.

[0054] This phenomenon may be influenced by the amount of the gap between the inner surface of the engagement hole of the tip member 43 and the workpiece W, the amount and / or quality of oil, threadlocker, etc. present in the gap, the dimensions of the workpiece W, etc. Other influencing factors may also exist. For example, repeated use may increase wear on the inner surface of the engagement hole of the tip member 43, causing the tip member 43 to rotate so that it shifts relative to the workpiece W when tightening is complete, which may reduce the maximum torque of the tool 40. At this time, a rotational force is applied to the tool 40, for example, around the axis J6, and this may appear in the load trend data of the sixth joint. Thus, the displays in Figures 6 and 8 can contribute to factor analysis when there is an abnormality in the work result.

[0055] Figure 9 shows trend data for the work result (rotation angle), and as shown in Figure 9, there are cases where the rotation angle gradually increases. The processor 51 determines that there is an abnormality in the rotation angle when, for example, the tilt exceeds the upper result change monitoring threshold shown in Figure 9. This determination may also be made when the upper result monitoring threshold is exceeded. For example, the ease of relative rotation between the workpiece W and the mating part to which the workpiece W is clamped may influence this phenomenon.

[0056] This phenomenon may be influenced by the amount of gap between the inner circumferential surface of the engagement hole of the tip member 43 and the workpiece W, the amount and / or quality of oil, threadlocker, etc. present in the gap, the dimensions of the workpiece W, etc. Other influencing factors may also exist. For example, if there is a large amount of oil in the gap, or if the inner circumferential surface of the engagement hole of the tip member 43 is significantly worn, the rotation angle of the tool 40 during the operation may increase. At this time, the user checks the amount of oil, the presence or absence of wear on the tip member 43, etc. Thus, displays such as Figures 6 and 9 can contribute to factor analysis when there is an abnormality in the work result. At this time, the user can also consider that no noteworthy changes appear in the load trend data of each joint in Figure 9, which can contribute to faster, easier, and more accurate factor analysis.

[0057] Furthermore, Figure 9 shows that the variability of the trend data of the work results is gradually increasing. In this way, the display devices 52 and 54A also display the trend of the amount of variability in the work results, so that the user can take this change in the amount of variability into consideration when performing factor analysis. When the amount of variability exceeds the variability threshold, the processor 51 may display this on the display devices 52 and 54A.

[0058] Figure 10 shows trend data for the work result (rotation angle), and as shown in Figure 10, there are cases where a tendency for the rotation angle to decrease can be observed. The processor 51 determines that an abnormality has occurred in which the rotation angle decreases when, for example, the tilt exceeds the upper result change monitoring threshold shown in Figure 10. This determination may also be made when the lower result monitoring threshold is exceeded. For example, the inclusion of foreign matter between the workpiece W and the mating part may affect this phenomenon.

[0059] In Figure 10, the rotation angle decreases from a certain point in time and remains in that state. This phenomenon may occur, for example, when burrs are generated during the machining process of the mating part, and these burrs become the foreign matter. In cases where the rotation angle decreases intermittently, unlike in Figure 10, foreign matter such as powder in the space where the work is being performed may intermittently be placed on the mating part, and the force control settings may not be appropriate. By displaying figures such as Figures 6 and 9, the user can perform factor analysis while also considering trend data of the load on each joint, which can contribute to faster, easier, and more accurate factor analysis.

[0060] In the above embodiment, the trend data of the work results is displayed along with the trend of changes in the load on each joint. Alternatively, instead of steps S1-6 to S1-9, the processor 51 may receive the changes in the result data along with the additional information from the control device 30. Or, instead of steps S1-7 to S1-9, the processor 51 may determine whether or not there has been a change in the result data based on the result data received in step S1-6. In these cases, in step S1-10, the processor 51 displays the changes in the work result data along with the trend of changes in the load on each joint on the display devices 52 and 54A. Examples of changes in the result data that are displayed include characters, diagrams, etc., indicating that the work result data (torque, rotation angle, rotation speed, etc.) has increased, decreased, or is abnormal.

[0061] Alternatively, instead of the processor 51 performing steps S1-6 to S1-10, the processor 51 may display the results of the work along with the trend of changes in the load on each joint on the display devices 52 and 54A. The displayed results of the work may include: the work was successful, the work failed, the work was successful but the torque value was large, the work was successful but the rotation angle was large, the work was successful but the rotation speed was low, etc. Preferably, these results of the work include information such as torque (force), rotation angle, and rotation speed during the work, along with information on whether the work was successful or not. The processor 51 receives the results of the work from the control device 30, or makes a determination or estimation based on the data received from the control device 30. In this case as well, the same effects as when performing steps S1-1 to S1-10 can be achieved.

[0062] In the above embodiment, for example as shown in Figure 11, the force at the sixth joint may exceed the warning criterion multiple times before the torque during operation tends to gradually decrease and the force at the sixth joint gradually increases. The gradual increase in the force at the sixth joint suggests the possibility of effects, including malfunctions, affecting the arm 20. In Figure 11, the warning criterion is shown by a solid line extending horizontally, and the force at the sixth joint during the 12th, 14th, and 16th operations from the most recent operation exceeds the warning criterion. Such warning phenomena may occur, for example, due to inappropriate force control settings and a change in the workpiece lot W. When such a phenomenon occurs that exceeds the warning criterion, the processor 51 determines, based on the trend of changes in the load at each joint, that there is a warning of an abnormality affecting the arm 20, and displays the determination result on the display devices 52 and 54A. This configuration is useful for eliminating undesirable effects on the arm 20 at an early stage.

[0063] Furthermore, as shown in Figure 11, the processor 51 determines that the work is abnormal when the slope of the trend data of the work results exceeds the result change monitoring threshold, and displays this using a focus position indicator (an approximation line of the slope of the relevant part). The processor 51 also displays the presence of the warning signs on the display devices 52 and 54A in a manner different from the display of the abnormality. In Figure 11, the presence of the warning signs is indicated by a rectangular solid line. This configuration can lead to the user understanding the relationship between work abnormalities and warning signs, and to the efficiency of factor analysis.

[0064] In the above embodiments and each of the above modifications, the processor 51 may be configured to determine the type of abnormality in the work based on the abnormality type determination program 53C stored in the storage unit 53. For example, in the example of Figure 11, the processor 51 determines that the work is abnormal when the slope of the trend data of the work results exceeds the result change monitoring threshold. The processor 51 may also estimate the cause or type of the abnormality based on the trend data of the load on each joint, and then determine the cause or type of the abnormality.

[0065] As shown in the example in Figure 11, when the torque value during operation gradually decreases and the load on the sixth joint gradually increases, the cause or type of the abnormality may be an inappropriate setting of the force control. If the processor 51 stores information on various causes or types, the trend of changes in the load on each joint corresponding to each of the various causes or types, and the trend of changes in the result data corresponding to each of the various causes or types in the storage unit 53, then the above estimation or determination becomes possible. This configuration leads to easier identification of the cause when an abnormality occurs, and improved efficiency as a result of this simplification.

[0066] Even when the load rate applied to each joint of the arm 20 does not exceed an allowable value and the arm 20 does not stop, it is undesirable for a large force to be repeatedly applied to only a specific joint. As described above, the control device 30 stops the arm 20 when the load rate of each joint exceeds a set allowable value. The processor 51 also makes the above estimation based at least on the trend of the change in the load rate applied to each joint which is smaller than the allowable value. This configuration makes it easier to detect undesirable movements of the arm 20, such as the repeated application of a large torque to only a specific joint.

[0067] Furthermore, in the above embodiment and each of the above modifications, as described above, the control device 30 stops the arm 20 when the load rate of each joint exceeds a set allowable value. The processor 51 also displays the trend of changes in the load rate applied to each joint that is smaller than the allowable value on the display devices 52 and 54A. This configuration can contribute to preventing failure of the arm 20, for example, due to repeated application of large forces to only specific joints.

[0068] In the above embodiments and each of the above modifications, the processor 51 may be configured to determine the cause or type of an abnormality in the work based on the learning program 53D stored in the memory unit 53. In this case, when there is an abnormality in the work, the processor 51 receives information regarding the cause or type of the abnormality and performs learning to estimate or determine the cause or type based at least on the trend of the change in the load and the information. An example of learning is machine learning, including deep learning.

[0069] An example of the aforementioned information is information regarding the cause or type of the abnormality that the user inputs using input devices 34, 54, etc., for the work at a certain work position. This information may include, for example, information indicating that the force control setting is not appropriate, information indicating that the posture of the arm 20 is not appropriate, or information indicating that the lubricant between the workpiece W and the other party is not appropriate. This information is linked to the work at that work position and stored in the memory units 33, 53. This information may also include visual information obtained by a visual sensor 50, etc., or information regarding the cause or type of the abnormality determined by the processors 31, 51 based on the visual information.

[0070] Furthermore, the processor 51 performs the learning process based on the multiple pieces of information and the trend data of load changes related to the work associated with them, and obtains a trained model for the arm 20. As a result, the processor 51 can use the trained model to estimate or determine the cause or type of abnormality in the work performed by the arm 20, based on the trend data of load changes newly obtained during the work. This estimation or determination may also be performed by the processor 31, other control devices, or other computers.

[0071] Furthermore, when creating the trained model, the processor 51 may perform the training based on a plurality of pieces of information and trend data of changes in workload and trend data of work results associated with that information.

[0072] Furthermore, when creating the trained model, the processor 51 may perform the training based on a plurality of pieces of information, trend data of load changes, trend data of work results, and calculation models of the arm 20 and tool 40. The calculation model includes information necessary for the training calculation, such as the dimensions, weight, center of gravity position, and connection relationships of each component of the arm 20, tool 40, etc. In this case, it becomes possible to perform the estimation or determination using the trained model even for arms with different specifications from arm 20.

[0073] In the above embodiment, the processor 51 displays an abnormality in steps S1-5 and S1-10. Alternatively, a configuration can be adopted in which the processor 51 displays load trend data and work result trend data when it receives a user request and there are no notable changes or abnormalities. Even when this configuration is adopted, the information in the trend data is useful, as in the above embodiment, for deciding to advance the maintenance timing, deciding to change the arm 20 to another arm, setting the posture change of the arm 20 during the work, etc.

[0074] In addition, in the above embodiments and each of the above modifications, the arm 20 may perform operations other than those described above using the tool 40. Examples of operations other than those described above include rotating a bottle cap (workpiece) to attach it to a mating part, or rotating a car spark plug socket (workpiece) to attach it to a mating part (vehicle body). Another example of an operation other than those described above is rotating a screw part W, such as a nut, to remove it from a mating part. The arm 20 may also perform other operations that involve rotating a workpiece. In these cases as well, the above effects can be achieved.

[0075] Furthermore, in the above embodiments and each of the above modifications, the tip of the arm 20 is configured to directly support the workpiece, and the workpiece may rotate due to the rotation of the outermost arm member 26. In this case, the tip of the arm 20 functions as a tool 40, and the above effects can be achieved.

[0076] In addition, in the above embodiments and each of the above modifications, it is also possible to use a configuration in which the output of a force sensor (torque sensor) provided between the arm 20 and the tool 40 or a force sensor (torque sensor) provided on the tool 40 is used. The force sensor is a known 6-axis sensor, etc., and is used for force control during work. Even in this case, the processors 31 and 51 can calculate the load applied to each joint during work using the detected value of the force sensor during work and a calculation model of the arm 20 and tool 40, and the processor 51 can achieve the same functions as in the above embodiments using the calculated load.

[0077] While embodiments of this disclosure have been described in detail, this disclosure is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the idea and intent of this disclosure derived from the claims and their equivalents. For example, in the embodiments described above, some configurations or steps can be omitted or added depending on the circumstances, without being bound by the above examples. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments above.

[0078] [Note 1] A work monitoring system for monitoring an arm that repeatedly rotates a workpiece at one or more work positions, comprising: a display device; and a processor, wherein the processor is configured to store the load applied to the arm by the work at each of the one or more work positions in a storage unit, and the processor is capable of displaying the trend of changes in the load for the repeatedly performed work on the display device. [Note 2] The work monitoring system according to Note 1, wherein the processor stores the result data of the work in the storage unit each time the work is performed, and the processor is capable of displaying changes in the result data together with the trend of changes in the load on the display device. [Note 3] The work monitoring system according to Note 1, wherein the processor is capable of displaying the results of the work together with the trend of changes in the load on the display device. [Note 4] The work monitoring system according to Note 1, wherein the processor is configured to determine whether or not there is an abnormality in the work based on at least the result data of the work, and the processor is configured to estimate or determine the cause or type of the abnormality based on at least the trend of the change in the load. [Note 5] The work monitoring system according to any one of Notes 1 to 3, wherein the processor is configured to determine whether or not there is a precursor of an abnormality affecting the arm based on at least the trend of the change in the load, and the processor is configured to display the presence of the precursor on the display device. [Note 6] The work monitoring system according to Note 5, wherein the processor is capable of displaying on the display device whether or not there is an abnormality in the work determined based on at least the result data of the work, and the processor is configured to display the presence of the precursor on the display device in a manner different from the display of whether or not there is an abnormality.[Note 7] The work monitoring system according to Note 1, wherein the control device for the arm is configured to stop the arm when it exceeds an allowable value set for each of the plurality of joints of the arm, and the processor is configured to display on the display device the trend of change of the load rate applied to one or more of the plurality of joints that is smaller than the allowable value, or to estimate or determine the cause or type of abnormality when there is an abnormality in the work, at least based on the trend of change of the load rate that is smaller than the allowable value. [Note 8] The work monitoring system according to Note 1, wherein the processor is configured to receive information regarding the cause or type of abnormality when there is an abnormality in the work, and to learn in order to estimate or determine the cause or type of abnormality at least based on the trend of change of the load and the information.

[0079] 1: Work monitoring system 10: Robot 20: Arm 21-26: Arm member 27: Motor 28: Force sensor 30: Control device 31: Processor 32: Display device 33: Memory unit 33A: Operation program 33B: Force data transmission program 33C: Result data transmission program 34: Input device 34A: Display device 40: Tool 41: Drive device 51: Processor 52: Display device 53: Memory unit 53A: Load result monitoring program 53B: Work abnormality monitoring program 53C: Abnormality type determination program 53D: Learning program 54: Input device 54A: Display device 101-103: Work position 102: Work position 103: Work position W: Work

Claims

1. A work monitoring system for monitoring an arm that repeatedly rotates a workpiece at one or more work positions, comprising a display device and a processor, wherein the processor is configured to store in a memory the load applied to the arm by the work at the one or more work positions, and the processor is capable of displaying the trend of changes in the load of the repeatedly performed work on the display device.

2. The work monitoring system according to claim 1, wherein the processor stores the result data of the work in the storage unit each time the work is performed, and the processor can display changes in the result data together with the trend of changes in the load on the display device.

3. The work monitoring system according to claim 1, wherein the processor is capable of displaying the results of the work along with the trend of the change in the load on the display device.

4. The work monitoring system according to claim 1, wherein the processor is configured to determine whether or not there is an abnormality in the work based on at least the result data of the work, and the processor is configured to estimate or determine the cause or type of the abnormality based on at least the trend of the change in the load.

5. The work monitoring system according to any one of claims 1 to 3, wherein the processor is configured to determine whether or not there are signs of an abnormality affecting the arm, based at least on the trend of the changes in the load, and the processor is configured to display on the display device that there are signs of an abnormality.

6. The work monitoring system according to claim 5, wherein the processor is capable of displaying on the display device whether or not there is an abnormality in the work, determined at least based on the result data of the work, and the processor is configured to display on the display device that there is a warning sign in a manner different from the display of whether or not there is an abnormality.

7. The work monitoring system according to claim 1, wherein the control device for the arm is configured to stop the arm when it exceeds a set tolerance value for each of the plurality of joints of the arm, and the processor is configured to display on the display device the trend of change of the load rate applied to one or more of the plurality of joints that is smaller than the tolerance value, or to estimate or determine the cause or type of abnormality when there is an abnormality in the work, at least based on the trend of change of the load rate that is smaller than the tolerance value.

8. The work monitoring system according to claim 1, wherein the processor is configured to receive information regarding the cause or type of an abnormality when there is an abnormality in the work, and to perform learning to estimate or determine the cause or type of the abnormality based at least on the trend of the change in the load and the information.

Images