Disconnection detection method and disconnection detection device

Abstract

To provide a disconnection detection method and disconnection detection device that are capable of detecting strand disconnection even when a device on which a cable is mounted is in actual operation.SOLUTION: A disconnection detection method for detecting disconnection of a plurality of strands constituting a conductor of a cable 10 wired in a device 11, which is caused by motion of the device 11 includes: a data acquisition step of acquiring motion information data 31, which is data showing changes over time in information about motion of the device 11, and resistance value data 32, which is data of a resistance value of the conductor that changes in time series due to the motion of the device 11; an analysis step of analyzing the resistance value data 32 on the basis of the motion information data 31 acquired in the data acquisition step and acquiring an index value to detect strand disconnection; and a disconnection detection step of detecting the strand disconnection on the basis of the index value in the analysis step.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wire break detection method and a wire break detection device. [Background technology]

[0002] In cables wired to moving parts of equipment such as industrial robots, the wires that make up the conductor gradually break due to repeated bending, twisting, and other movements of the moving parts, and ultimately lead to a break in the conductor. Therefore, it is desirable to detect the break in the wires and replace the cable before the entire conductor breaks.

[0003] When the number of broken wires that make up the conductor is small, the change in the resistance value of the conductor is very slight, making it difficult to distinguish from noise during detection. For this reason, in the past, when the resistance value of the conductor rose by several tens of percent from its initial value, it was often determined that a complete break was imminent and that a break had occurred at this point. However, in this case, there was little time (or number of operations) between the detection of a break and the complete break of the entire conductor, and there was a risk that the entire conductor would break before the cable could be replaced, causing equipment such as industrial robots to stop operating.

[0004] Patent Document 1 proposes a method for detecting wire breakage based on the results of measuring the resistance of the conductor when the cable is operated (bent, twisted, etc.) at a constant cycle and analyzing the fluctuations in the resistance using frequency analysis. This method has high sensitivity, making it possible to detect wire breakage even when, for example, only one wire is broken. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2021-162570 A Summary of the Invention [Problem to be solved by the invention]

[0006] Users (equipment users) of industrial robots and other devices and manufacturers (equipment manufacturers) of such devices perform maintenance of the devices. In the maintenance of the devices, the operation of the industrial robots and other devices to be managed is stopped and inspection is performed, but it is desirable to be able to perform maintenance even when the devices are in operation in order to prevent sudden stoppage of the devices due to failures during operation. In particular, it is desirable to be able to detect whether or not a wire in a cable mounted on the devices such as industrial robots is broken while the devices are in operation.

[0007] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a method and device for detecting a break in a wire, which is capable of detecting a break in a wire even when a device in which a cable is mounted is in operation. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the present invention provides a wire break detection method for detecting that a wire of a cable having a conductor composed of a plurality of wires and wired to an apparatus is broken due to the operation of the apparatus, the wire break detection method comprising: a data acquisition step of acquiring operation information data which is data indicating changes over time in information related to the operation of the apparatus, and resistance value data which is data on the resistance value of the conductor which changes over time due to the operation of the apparatus; an analysis step of analyzing the resistance value data based on the operation information data acquired in the data acquisition step to acquire an index value for detecting a break in the wire; and a wire break detection step of detecting a break in the wire based on the index value acquired in the analysis step.

[0009] In addition, for the purpose of solving the above-mentioned problems, the present invention provides a wire break detection device having a conductor composed of a plurality of wires, which detects that the wire of a cable wired to an apparatus is broken due to the operation of the apparatus, the wire break detection device comprising: a data acquisition processing unit that acquires operation information data, which is data indicating changes over time in information related to the operation of the apparatus, and resistance value data, which is data on the resistance value of the conductor that changes over time due to the operation of the apparatus; an analysis processing unit that analyzes the resistance value data based on the operation information data acquired by the data acquisition processing unit, and acquires an index value for detecting a break in the wire; and a wire break detection processing unit that detects a break in the wire based on the index value acquired by the analysis processing unit.

[0010] In addition, for the purpose of solving the above-mentioned problems, the present invention provides a wire break detection device having a conductor composed of a plurality of wires, which detects that the wire of a cable wired to an apparatus is broken due to the operation of the apparatus, the wire break detection device comprising: a data acquisition processing unit that acquires resistance value data, which is data on the resistance value of the conductor that changes over time due to the operation of the apparatus; an analysis processing unit that generates operation information data from the resistance value data, which is data that indicates changes over time in information related to the operation of the apparatus, analyzes the resistance value data based on the operation information data, and acquires an index value for detecting a break in the wire; and a wire break detection processing unit that detects a break in the wire based on the index value in the analysis processing unit. Effect of the Invention

[0011] According to the present invention, it is possible to provide a wire break detection method and a wire break detection device that are capable of detecting a break in a wire even when a device in which a cable is mounted is in operation. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic configuration diagram of a wire break detection device according to an embodiment of the present invention; [Diagram 2] 13(a) to 13(c) are diagrams illustrating the analysis process. [Diagram 3] FIG. 1A is a flow diagram of a disconnection detection method according to an embodiment of the present invention, and FIG. [Figure 4] 6(a) to 6(c) are diagrams showing an example of a change in index value I. [Diagram 5] FIG. 13 is a diagram showing an example of a change in an index value Ix. [Figure 6] FIG. 11 is a flow diagram of an analysis process according to another embodiment of the present invention. [Figure 7] 11A and 11B are diagrams illustrating disconnection detection for a plurality of movable parts. [Figure 8] FIG. 11 is a flow diagram of an analysis process according to a modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] [Embodiment Mode] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0014] FIG. 1 is a schematic diagram of a disconnection detection device 1 according to the present embodiment. The disconnection detection device 1 is a device that detects that a cable 10 wired to an arbitrary device (managed device) 11 managed by an device user or device manufacturer is bent, twisted, or the like by an operation based on the actual operation of the device 11, and that the wires, which are made of metal wires and form a conductor of the cable 10, are broken by the operation. The device 11 has a movable part 11b, and the cable 10 is wired so as to pass through the movable part 11b. By operating the movable part 11b of the device 11, the cable 10 is repeatedly bent, twisted, or the like. FIG. 1 shows a case where the device 11 to which the cable 10 is wired is an industrial robot 11a. The conductor to be detected for disconnection in the cable 10 is made of a stranded conductor formed by twisting a plurality of strands together.

[0015] Hereinafter, "breakage of a wire" means that each of the wires constituting the conductor of the cable 10 is broken. In addition, "breakage progression state of the conductor" means the breakage ratio, i.e., the number of broken wires among the number of wires constituting the conductor, due to repeated bending, twisting, and other operations applied to the cable 10. The breakage progression state of the conductor can be expressed as the ratio (%) of the number of broken wires to the total number of wires constituting the conductor. For example, the breakage progression state of a wire constituting the conductor indicates that all of the wires constituting the conductor are broken when the breakage ratio is 100%. In other words, the breakage progression state of the conductor can be said to be the breakage progression state of the cable 10.

[0016] Moreover, "conductor breakage" means that the conductor breakage rate reaches a preset rate and reaches a state where it is determined that the conductor has broken. For example, the state where it is determined that the conductor has broken is set to when the resistance increase rate (the rate of increase in the resistance value of the conductor relative to the initial resistance value of the conductor) of the conductor constituting the cable 10 exceeds 20%, and the conductor breakage rate (= the progress of the conductor breakage) at this time is, for example, 80% or more. Conductor breakage indicates the time when it is determined that the cable 10 has reached the end of its life (= the cable life), and serves as a guide for encouraging replacement of the cable 10.

[0017] A robot control device 12 for controlling the industrial robot 11a is connected to the industrial robot 11a. The robot control device 12 is equipped with an operation control unit 12a for controlling the operation of the industrial robot 11a (operation of the movable part 11b). The robot control device 12 stores an operation program (not shown) in which the order of operation of the movable part 11b, the angle of operation, the speed, etc. are preset, and the operation control unit 12a operates the industrial robot 11a according to the operation program.

[0018] The robot control device 12 is also equipped with a resistance value detection unit 12b that detects the resistance value of the conductor of the cable 10. The detection method of the resistance value detection unit 12b is not particularly limited. That is, the resistance value detection unit 12b may have any configuration as long as it can detect the resistance value of the conductor, and may be configured to obtain the resistance value from the ratio of the voltage applied to the conductor and the current flowing through the conductor. The resistance value detection unit 12b does not have to be mounted on the robot control device 12, and may be mounted on a unit (module) dedicated to resistance value detection arranged between the industrial robot 11a and the disconnection detection device 1, or may be mounted on the disconnection detection device 1 or the industrial robot 11a. By mounting the resistance value detection unit 12b on the unit (module), the industrial robot 11a, the resistance value detection unit 12b, and the robot control device 12 can be connected to each other and the resistance value of the conductor of the cable 10 can be detected without making complex improvements to the structures of the industrial robot 11a and the robot control device 12. The resistance value detected by the resistance value detector 12b is transmitted to the disconnection detector 1 and stored as resistance value data 32 in the memory 3 of the disconnection detector 1.

[0019] (Disconnection detection device 1) The disconnection detection device 1 has a control unit 2 and a storage unit 3. A display unit 4 is connected to the disconnection detection device 1, and is configured to be able to display various information such as operation information data 31, resistance value data 32, or the result of disconnection detection, which will be described later, on the display unit 4. The disconnection detection device 1 is also provided with an input device 5 such as a keyboard, and various settings and the display contents of the display unit 4 can be operated by inputting information from the input device 5. The display unit 4 may be configured as a touch panel display so that the display unit 4 also functions as the input device 5. Furthermore, the display unit 4 and the input device 5 do not need to be connected to the disconnection detection device 1 by wire, and may be connected wirelessly. In this case, the display unit 4 and the input device 5 may be, for example, a smartphone or a tablet.

[0020] The control unit 2 has a data acquisition processing unit 21, an analysis processing unit 22, a disconnection detection processing unit 23, and a cable life prediction processing unit 24. The data acquisition processing unit 21, the analysis processing unit 22, and the disconnection detection processing unit 23 are realized by appropriately combining a calculation element such as a CPU, memories such as RAM and ROM, software, an interface, a storage device, and the like.

[0021] (Data acquisition processing unit 21) The data acquisition processing unit 21 performs a data acquisition process to acquire operation information data 31, which is data indicating changes over time in information related to the operation of the device 11, and resistance value data 32, which is data on the resistance value of a conductor that changes over time due to the operation of the device 11. The operation of the device 11 is, for example, the operation of the movable part 11b when the device 11 is in actual operation. The data acquisition process corresponds to a data acquisition step of the present invention. The data acquisition processing unit 21 acquires the operation information data 31 and the resistance value data 32 during the actual operation of the device 11.

[0022] In this embodiment, angle information of the movable part 11b is used as information related to the operation of the movable part 11b. That is, in this embodiment, the operation information data 31 is data indicating a change over time in the angle α of the movable part 11b. The angle information of the movable part 11b may be acquired from an operation program stored in the robot control device 12, or may be acquired by a sensor attached to the movable part 11b of the industrial robot 11a or by detecting the drive current of a motor that drives the movable part 11b. In addition, the resistance value data 32 may be received from the resistance value detection unit 12b of the robot control device 12.

[0023] (Analysis processing unit 22) The analysis processing unit 22 performs an analysis process for analyzing the resistance value data 32 based on the motion information data 31 acquired by the data acquisition processing unit 21. The analysis process corresponds to an analysis step of the present invention. In this embodiment, the analysis processing unit 22 calculates, for each motion state (here, angle α), an average value of the resistance value during the motion state for a predetermined period of time.

[0024] 2(a) to (c) are diagrams for explaining the analysis process. As shown in FIG. 2(a), when the industrial robot 11a is in operation, the movable part 11b moves intermittently at various speeds. In the analysis process, of the operation information data 31 and the resistance value data 32, only data from a predetermined period (e.g., 30 minutes) is analyzed. The period to be analyzed can be set appropriately taking into consideration the operation cycle of the movable part 11b, etc. When the angle α of the movable part 11b is set to an arbitrary angle α k Since the time when the angle α of the movable part 11b is an arbitrary angle α k The resistance value r when nk (n is an integer equal to or greater than 1). In the example of FIG. 2(a), the angle α k Therefore, the resistance value r corresponding to times t1, t2, . . . , t7 is 1k ,r 2k ,···,r 7k Then, the analysis processing unit 22 extracts the average resistance value r k Request.

number

[0025] In this embodiment, the average value r k From this, angle α k The index value Δr is the normalized value obtained by subtracting the average value at k That is, the angle α k The average value r0 at r = 0 is calculated using the following formula (2), and the index value Δr k asked for.

number

[0026] Similarly, the index value Δr k By calculating the angle α as shown in Figure 2(b), k Index value Δr for kThe resistance value of the conductor changes due to the influence of the strain applied by the movement of the movable part 11b even when there is no break in the wire. In the illustrated example, the angle α k When the angle becomes ±90 degrees, the resistance value of the conductor increases due to the influence of distortion. When a break occurs in a wire constituting the conductor, the distance between the wires at the break point changes in response to the movement of the movable part 11b, and the resistance value of the conductor fluctuates accordingly. For example, as shown in FIG. 2(b), if an initial break is defined as when the first of the multiple wires constituting the conductor is broken, the resistance value of the conductor increases with the occurrence of the initial break. As a result, when a break occurs in a wire, the resistance value of the conductor increases when the wire is rotated at a predetermined angle α k Resistance value (index value Δr k ) becomes larger. Such changes in resistance are very small and are usually difficult to observe because they are buried in noise components. However, the average resistance value over a certain long period of time, r k and further, the angle α k The difference between the average resistance value r0 at k By doing so, the index value Δr k The analysis processing unit 22 extracts the change in the resistance value of the conductor due to the breakage of the wire from the change in the angle α k Index value Δr for each k The calculation results are stored in the storage unit 3 as analysis data 33.

[0027] Figure 2(c) shows the time change of the graph in Figure 2(b), and the index value Δr k In the illustrated example, the index value Δr k Basically, when a break occurs, the change in the resistance value of the conductor (index value Δr k After that, as the wire breakage progresses (i.e., the proportion of wire breakage increases), the change in resistance (index value Δr k ) is expected to become larger.

[0028] (Disconnection detection processing unit 23) The disconnection detection processing unit 23 performs a disconnection detection process to detect a disconnection of the wires constituting the conductor based on the analysis result (analysis data 33) in the analysis processing unit 22. The disconnection detection process corresponds to a disconnection detection step of the present invention. In this embodiment, the disconnection detection processing unit 23 detects an index value Δr k Based on this, breaks in the wires that make up the conductor are detected.

[0029] The disconnection detection processing unit 23 detects the predetermined angle α k The index value Δr k has become larger than a preset threshold value. By appropriately setting this threshold value, it is possible to detect an incipient breakage (when the wires begin to break) or to detect that a predetermined breakage has progressed. For example, in order to detect that a breakage has progressed to a state two weeks before all of the wires that make up the conductor are completely broken, operation information data 31 and resistance value data 32 from when the conductor is new to when it is completely broken are obtained in advance, and a time change such as that shown in FIG. 2(c) is created. Then, using the data transition in FIG. 2(c), the angle α k The index value Δr k is set as the threshold value for detecting a disconnection. k The index value Δr k By determining whether the angle α is greater than a preset threshold value, it is possible to detect whether a break has occurred in the wire or whether the conductor has reached a predetermined breakage progression state. k The index value Δr k When the index value Δr becomes larger than a preset threshold, an alarm may be issued. The disconnection detection processing unit 23 stores the result of the disconnection detection (determination result) in the storage unit 3 as disconnection detection data 34. A plurality of thresholds may be set in stages, and the index value Δr k It may be possible to detect the current extent to which the disconnection has progressed by comparing the detected disconnection voltage with a plurality of threshold values.

[0030] However, without being limited to this, the break detection processing unit 23 may be configured to detect a break in the wire using machine learning based on the analysis data 33. In other words, the break detection processing unit 23 may use a trained model created in advance to detect a break in the wire from the analysis results that are the subject of break detection. As the learning model, the analysis results when there is no break in the wire (the above-mentioned index value Δr k ) may be used. More specifically, for example, anomaly detection using an autoencoder may be used to detect the presence or absence of a break. When anomaly detection using an autoencoder is performed, the angle α k Index value Δr for each k The index value Δr in the normal state is learned repeatedly. k In the autoencoder that has been repeatedly trained, the index value Δr k Even if you enter the value Δr k is output as a predicted value. Therefore, the input index value Δr k If some abnormality is included in the input value, a deviation (error) occurs between the input value and the predicted value. Therefore, by determining whether the degree of this deviation is greater than a preset threshold, it is possible to detect the beginning of a wire breakage. In addition, by appropriately adjusting the threshold, it is also possible to detect whether the conductor has reached a predetermined breakage progression state. Note that the detection of anomalies using an autoencoder is not limited to this, and various machine learning algorithms, such as a support vector machine, can be used to detect wire breakage.

[0031] In this embodiment, a plurality of industrial robots 11a (and a robot control device 12) are connected to the wire breakage detection device 1, and the wire breakage detection of the wire constituting the conductor in the cable 10 is performed by the plurality of industrial robots 11a. Therefore, the operation information data 31 and the resistance value data 32 can be efficiently collected, and data for machine learning can be efficiently collected, and a learned model can be created by learning using a large amount of data. Therefore, the prediction accuracy of the learned model can be improved. In the example of FIG. 1, a robot control device 12 is provided for each industrial robot 11a, but a configuration in which a plurality of industrial robots 11a are controlled by one robot control device 12 may be used. In addition, the wire breakage detection device 1 may be equipped with a function as the robot control device 12.

[0032] (Cable life prediction processing unit 24) The cable life prediction processing unit 24 calculates the index value Δr k Based on the value of , a cable life prediction process is performed to predict the time until the conductor breaks, i.e., the time until the cable 10 reaches its end of life (hereinafter referred to as cable life). The cable life prediction processor 24 may predict the cable life taking into consideration the progress of the break detected by the break detection processor 23 and the operating conditions of the movable part 11b. For example, a time change such as that shown in FIG. 2(c) is acquired in advance, and the current index value Δr is calculated by referring to this time change. k It may be possible to predict how much time will elapse before the cable life is reached from the time corresponding to the cable life prediction process. The prediction result of the cable life prediction process is stored in the storage unit 3 as life prediction data 35. Note that the cable life prediction processor 24 is not essential and can be omitted.

[0033] (Disconnection detection method) Fig. 3(a) is a flow diagram of the disconnection detection method according to the present embodiment. The flow in Fig. 3(a) is started when the device 11 starts operating. As shown in Fig. 3, first, in step S1, the data acquisition processing unit 21 starts acquiring operation information data 31 and resistance value data 32 from the resistance value detection unit 12b. After that, in step S2, the analysis processing unit 22 judges whether there is unanalyzed resistance value data 32 in the storage unit 3 (for example, whether there is 30 minutes of unanalyzed data). Note that in step S2, it may be judged whether a predetermined time has passed since the previous analysis (for example, whether 30 minutes have passed).

[0034] 3B, in the analysis process, in step S31, the analysis processing unit 22 calculates the angle α k In step S32, the resistance value is extracted for each angle αk using the above equations (1) to (3). k Then, in step S33, the analysis processing unit 22 calculates the index value Δr k The calculation result is stored in the storage unit 3 as the analysis data 33, and then the process returns to step S4 in FIG.

[0035] In step S4, a disconnection detection process is performed. In the disconnection detection process, the disconnection detection processing unit 23 detects an index value Δr k Based on the calculation result (analysis data 33), it is detected whether a break has occurred in the wire (whether a break has started to occur in the wire). Note that by appropriately adjusting the threshold value, it is also possible to detect whether the conductor has reached a desired break progression state. The detection result is stored in the memory unit 3 as break detection data 34. In addition, the detection result may be displayed on the display 4, or an alert may be issued when a break is detected.

[0036] Then, in step S5, it is determined whether the operation of the device 11 has been completed. If the determination in step S5 is NO, the process returns to step S2. If the determination in step S5 is YES, in step S6, data acquisition by the data acquisition processing unit 21 is terminated, and the process is terminated. Although not shown in the figure, a cable life prediction process may be performed after step S6.

[0037] (Other embodiments) In the above embodiment, the angle α k Index value Δr for each k However, the present invention is not limited to this, and other index values ​​may be used. In the following, an embodiment using frequency analysis will be described.

[0038] In this embodiment, the analysis processing unit 22 performs frequency analysis of the motion information data 31 and the resistance value data 32 for a predetermined period of time. More specifically, a fast Fourier transform (FFT) is performed on the motion information data 31 and the resistance value data 32 for a predetermined period of time (e.g., 30 minutes). By performing a fast Fourier transform on the motion information data 31 (here, data on the change over time in the angle α), the angle α(t) is converted to the following equation (4). Note that ω in equation (4) na is the angular frequency, α ωn is the angular frequency ω na (n is an integer equal to or greater than 1).

number

[0039] Similarly, by performing a fast Fourier transform (FFT) on the resistance data 32, the resistance value r(t) is converted into the following equation (5). mr is the angular frequency, r ωm is the angular frequency ω mr (m is an integer equal to or greater than 1).

number

[0040] Then, the analysis processing unit 22 extracts an arbitrary frequency component α ωn and an arbitrary frequency component r of resistance value data 32 ωm Multiplying this gives the index value I = α ωn ×r ωm Here, both frequency components α ωn ,r ωm were multiplied for all combinations to obtain n×m index values ​​I. However, this is not limiting, and only combinations that are likely to cause a change when a wire is broken may be picked up and used as the index value I.

[0041] As shown in FIG. 4(a), when the wires constituting the conductor are not broken, the strain applied to the conductor by the movement of the movable part 11b causes a distortion of ω na :ω mr When the movable part 11b is operated so as to repeatedly bend the cable 10 left and right, the strain of the conductor increases when the angle is maximum left and right in one cycle of operation, and the resistance value increases twice in one cycle of operation. In such a case, ω na :ω mr The index value I for the combination of I = 1:2 is large even when the wire is not broken.

[0042] Furthermore, as shown in Fig. 4(b), when a break occurs in the wire that constitutes the conductor, ω na :ω mr When the cable 10 is repeatedly bent left and right, the distance between the wires at the broken part increases when the cable 10 is bent in one direction, either left or right, and the resistance value increases. na :ω mr The index value I of the combination where the ratio ω = 1:1 is large. Note that the ratio ω na :ω mrwill differ. For example, the index value I, which has increased due to strain, may become even larger when a wire breaks. If the wire breaks further (i.e., if the number of broken wires increases), the index values ​​I for various combinations are expected to increase, as shown in Fig. 4(c). Note that the graphs shown in Figs. 4(a) to (c) are plotted against the angular frequency ω na The frequency component α of the angle corresponding to ωn and the angular frequency ω on the vertical axis mr The frequency component of the resistance r ωm The magnitude (intensity) of the index value I multiplied by both angular frequencies ω na ,ω mr The intersections are shown in shades of gray.

[0043] The break detection processing unit 23 detects a break in the wires constituting the conductor based on the result of frequency analysis of both the operation information data 31 and the resistance value data 32 by the analysis processing unit 22. Here, the break detection processing unit 23 detects a break in the wires based on the index values ​​I of all combinations (n×m pieces) obtained by calculation in the analysis processing unit 22. The break detection processing unit 23 detects a break in the wires from the n×m index values ​​I that are targets for break detection, for example, by using a trained model created in advance. Here, the trained model can be an autoencoder that has repeatedly trained the index values ​​I when there is no break in the conductor, and break detection can be performed using anomaly detection using the autoencoder, as in the above embodiment.

[0044] Here, n × m index values ​​I are used, but since the number of data may become relatively large and the calculation load may become large, in order to reduce the number of data, it is also possible to use a combination of index values ​​I that are more affected by wire breakage. As described above, the effect of wire breakage is determined by the angle and the frequency ratio of resistance (ω na :ω mr ) becomes larger at an index value I where the ratio (for example, an integer of 1 or more) is reached. Therefore, the analysis processing unit 22 adds up the products of the frequency components where the frequency of the resistance value data 32 is x times that of the operation information data 31 (where x is an integer of 1 or more) to obtain the index value I xis calculated by the following formula (6), and the index value I obtained by the calculation is x A break in the wire may be detected based on the above.

number

[0045] Figure 5 shows the index value I x 1 is a diagram showing an example of the change in index value I1. In the example shown, even when there is no break in the wire, the index value I2 is relatively large due to the influence of the strain applied to the conductor. When an initial break occurs (at the position indicated by the symbol A), the index value I1 increases. As time passes and the break in the conductor progresses (the number of broken wires increases), the other index values ​​I3 and I4 also increase. In this way, these index values ​​I x It is possible to detect the progression of a conductor breakage using this method.

[0046] Fig. 6 is a flow diagram of an analysis process in another embodiment. As shown in Fig. 6, first, in step S34, a frequency analysis is performed on the resistance value data 32, and in step S35, a frequency analysis is performed on the motion information data 31. Then, in step S36, n x m index values ​​I are calculated, and in step S36, the calculation results of the index values ​​I are stored in the storage unit 3 as analysis data 33.

[0047] Furthermore, if the device 11 has multiple movable parts, a similar analysis can be performed for each movable part to detect disconnection. For example, as shown in Fig. 7, there are two movable parts 11b and 11c, and the angle of one movable part 11b is α and the angle of the other movable part 11c is β. When the data on the angles α and β of both movable parts 11b and 11c (operation information data 31) are subjected to a fast Fourier transform, the following equations (7) and (8) are obtained.

number

[0048] The analysis processing unit 22 calculates the frequency component α of the angle α of the movable part 11b. ωn and frequency component r of resistance rωm Multiplying all combinations of and gives the index value I α = α ωn ×r ωm The analysis processing unit 22 also calculates the frequency component β of the angle β of the movable part 11c. ωn and frequency component r of resistance r ωm Multiplying all combinations of and gives the index value I β =β ωn ×r ωm Calculate the following.

[0049] The state of breakage of the conductor in the movable part 11b moving at an angle α is expressed by the frequency component α ωn Frequency component r of resistance r related to ωm The breakage of the conductor in the movable part 11c moving at an angle β appears as a frequency component β of the angle β. ωn Frequency component r of resistance r related to ωm Therefore, the frequency component r ωm frequency component α ωn The index value I calculated by multiplying α (That is, the frequency component α ωn Frequency components related to r ωm Index value I with emphasis on α ) can be used to detect the breakage of the wire or the progress of the breakage of the conductor in the movable part 11b moving at an angle α. Similarly, the frequency component r ωm The frequency component β ωn The index value I calculated by multiplying β (That is, the frequency component β ωn Frequency components related to r ωm Index value I with emphasis on β ) can be used to detect the breakage of the wire or the progress of the breakage of the conductor in the movable part 11c moving at the angle β. In this way, when there are multiple movable parts 11b and 11c, the frequency component r of the resistance value r related to the operation of each of the movable parts 11b and 11c can be detected. ωm Index value I with emphasis on α ,I β By determining this, it becomes possible to detect the progress of breakage of the wire or the conductor for each of the movable parts 11b and 11c.

[0050] (Functions and Effects of the Embodiments) As described above, the wire break detection method of this embodiment includes a data acquisition process for acquiring operation information data 31, which is data indicating changes over time in information related to the operation of device 11, and resistance value data 32, which is data on the resistance value of the conductor that changes over time due to the operation of device 11; an analysis process for analyzing the resistance value data 32 based on the operation information data 31 acquired in the data acquisition process to acquire an index value for detecting a wire break; and a wire break detection process for detecting a wire break based on the index value in the analysis process.

[0051] By analyzing the resistance value data 32 based on the operation information data 31, it is possible to detect the resistance value that changes according to the operation, and based on the detection result, it is possible to detect a disconnection even when the device 11 in which the cable 10 is mounted is in operation. For example, the device 11, such as an industrial robot 11a used in a factory, has an overwhelmingly longer operating time than non-operating time during which maintenance can be performed. Therefore, by making the data collected during operation available, it is possible to collect more data, and the accuracy of disconnection detection using machine learning can be improved.

[0052] (Modification) In the above embodiment, the disconnection detection is performed using the motion information data 31 and the resistance value data 32, but if the motion information data 31 cannot be acquired for some reason, it is also possible to generate (or predict) the motion information data 31 from the resistance value data 32 and perform the disconnection detection. For example, the frequency analysis result of the resistance value data and the frequency analysis result of the motion information data may be stored in advance as a database in association with each other, data closest to the frequency analysis result of the measured resistance value data may be extracted from the database, and the index value I may be calculated using the frequency analysis result of the motion information data included in the extracted data. In this case, as shown in FIG. 8, instead of step S35 in FIG. 6, a process of extracting the frequency analysis result of the motion information data from a past database (DB) may be performed in step S38.

[0053] In addition, when the conductor is not broken, the strain applied to the conductor by the movement of the movable part 11b causes ω na :ω mr The index value I becomes larger when the ratio (for example, the ratio of integers) between the wires becomes larger, and this tendency continues to some extent even if the wire breakage progresses. Therefore, the index value I becomes larger due to the influence of strain, ω na :ω mr If the ratio is confirmed in advance, it is possible to generate the result of frequency analysis of the motion information data 31 using the result of frequency analysis of the resistance value data 32. In other words, it is possible to detect a disconnection without acquiring the motion information data 32.

[0054] More specifically, when calculating the index value I, the angular frequency ω na The frequency component α corresponding to ωn When is unknown, ω na =ω mr ω such as / 2 na :ω mr If you check the ratio of these factors in advance, you can get the angular frequency ω mr The frequency component r corresponding to ωn α ωn For example, when a bending motion in which the resistance value increases twice in one cycle of motion is applied, ωna :ω mr The index value I of the combination where ω = 1:2 is large. na =ω mr The index value I of the combination with α ωn Instead of r ωn / 2 Using this, the index value I can be calculated using the following equation (9). I=r ωn / 2 ×r ωm (9) However, both frequency components r ωn ,r ωm may be multiplied by all combinations to obtain n×m index values ​​I, or only combinations that are likely to cause a change when a wire is broken may be appropriately selected and used as the index value I.

[0055] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiment will be described by using the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiment.

[0056] [1] A wire break detection method for detecting that a wire of a cable (10) having a conductor composed of a plurality of wires and wired to a device (11) is broken due to operation of the device (11), the wire break detection method comprising: a data acquisition step of acquiring operation information data (31) which is data indicating changes over time in information related to the operation of the device (11) and resistance value data (32) which is data on the resistance value of the conductor which changes over time due to the operation of the device (11); an analysis step of analyzing the resistance value data (32) based on the operation information data (31) acquired in the data acquisition step to acquire an index value for detecting a wire break; and a wire break detection step of detecting a wire break based on the index value acquired in the analysis step.

[0057] [2] In the analysis step, for each of the operation states, the average value (r k) and normalizing the average value to obtain the index value, and in the disconnection detection process, a disconnection of the wire is detected based on the index value in the analysis process.

[0058] [3] The wire break detection method according to [1] or [2], wherein in the analysis step, a frequency analysis is performed on the operation information data (31) and the resistance value data (32) for a predetermined period, and the index value is obtained based on a result of the frequency analysis, and in the wire break detection step, a wire break is detected based on the index value in the analysis step.

[0059] [4] The wire break detection method according to [3], wherein in the analysis step, an arbitrary frequency component of the operation information data (31), which is a result of the frequency analysis, is multiplied by an arbitrary frequency component of the resistance value data (32) to calculate the index value (I), and in the wire break detection step, a wire break is detected based on the index value in the analysis step.

[0060] [5] In the analysis step, based on the result of the frequency analysis, the products of frequency components whose frequency is x times (where x is an integer equal to or greater than 1) the frequency of the resistance value data (32) are added to the operation information data (31) to obtain the index value (I x ) and in the disconnection detection step, a disconnection of the wire is detected based on the index value in the analysis step.

[0061] [6] A wire break detection method according to any one of [1] to [5], in which, in the wire break detection process, a trained model is created by previously training using training data including the index value when there is no break in the wire, and a break in the wire is detected from the index value that is the subject of wire break detection.

[0062] [7] A wire breakage detection device (1) having a conductor composed of a plurality of wires, the wire of a cable (10) being wired to an apparatus (11) and configured to detect a break in the wire due to operation of the apparatus (11), the wire breakage detection device (1) comprising: a data acquisition processing unit (21) that acquires operation information data (31) which is data indicating changes over time in information related to the operation of the apparatus (11) and resistance value data (32) which is data on the resistance value of the conductor which changes over time due to the operation of the apparatus (11); an analysis processing unit (22) that analyzes the resistance value data (32) based on the operation information data (31) acquired by the data acquisition processing unit (21) and acquires an index value for detecting a break in the wire; and a wire breakage detection processing unit (23) that detects a break in the wire based on the index value acquired by the analysis processing unit (22).

[0063] [8] A wire breakage detection device (1) having a conductor composed of a plurality of strands, the wire of a cable (10) being wired to an apparatus (11) and configured to detect a break in the wire due to operation of the apparatus (11), the wire breakage detection device (1) comprising: a data acquisition processing unit (21) that acquires resistance value data (32), which is data on the resistance value of the conductor that changes over time due to operation of the apparatus (11); an analysis processing unit (22) that generates operation information data (31), which is data showing changes over time in information related to the operation of the apparatus, from the resistance value data (32), analyzes the resistance value data (32) based on the operation information data (31), and acquires an index value for detecting a break in the wire; and a wire breakage detection processing unit (23) that detects a break in the wire based on the index value obtained by the analysis processing unit (22).

[0064] (Additional Note) Although the embodiment of the present invention has been described above, the invention according to the claims is not limited to the embodiment described above. It should be noted that not all of the combinations of features described in the embodiment are essential to the means for solving the problems of the invention. The present invention can be modified appropriately without departing from the spirit of the invention. [Explanation of symbols]

[0065] 1...Disconnection detection device 2...Control section 21...Data acquisition processing section 22...Analysis processing unit 23...Disconnection detection processing unit 3...Storage section 31...Operation information data 32…Resistance data 33…Analysis data 34…Disconnection detection data 10…Cable 11...device 11a…Industrial robots 11b...Movable part 12a...Motion control section 12b…Resistance detection section

Claims

1. 1. A method for detecting a break in a cable having a conductor composed of a plurality of wires and wired to a device, the method comprising the steps of: a data acquiring step of acquiring operation information data which is data showing a change over time in information related to the operation of the device, and resistance value data which is data on the resistance value of the conductor which changes over time due to the operation of the device; an analysis step of analyzing the resistance value data based on the operation information data acquired in the data acquisition step to acquire an index value for detecting a breakage of the wire; A break detection process for detecting a break in the wire based on the index value in the analysis process. Disconnection detection method.

2. In the analysis step, an average value of the resistance value during a predetermined period when the operation is in each of the operation states is calculated, and the index value is obtained by normalizing the average value. In the disconnection detection step, a disconnection of the wire is detected based on the index value in the analysis step. The method for detecting a disconnection according to claim 1 .

3. In the analyzing step, a frequency analysis is performed on the motion information data and the resistance value data for a predetermined period of time, and the index value is obtained based on a result of the frequency analysis. In the disconnection detection step, a disconnection of the wire is detected based on the index value in the analysis step. The method for detecting a disconnection according to claim 1 .

4. In the analyzing step, an arbitrary frequency component of the motion information data, which is a result of the frequency analysis, is multiplied by an arbitrary frequency component of the resistance value data to calculate the index value; In the disconnection detection step, a disconnection of the wire is detected based on the index value in the analysis step. The disconnection detection method according to claim 3.

5. In the analyzing step, the index value is calculated by adding up the products of frequency components in which the frequency of the resistance value data is x times (where x is an integer of 1 or more) the frequency of the motion information data based on the result of the frequency analysis; In the disconnection detection step, a disconnection of the wire is detected based on the index value in the analysis step. The disconnection detection method according to claim 3.

6. In the disconnection detection step, a disconnection of the wire is detected from the index value that is a detection target for a disconnection, using a trained model that is created by previously training using training data including the index value when there is no disconnection in the wire. The method for detecting a disconnection according to claim 1 .

7. A wire breakage detection device that detects that a wire of a cable having a conductor composed of a plurality of wires and wired to an apparatus is broken due to an operation of the apparatus, a data acquisition processing unit that acquires operation information data that is data showing changes over time in information related to the operation of the device, and resistance value data that is data on the resistance value of the conductor that changes over time due to the operation of the device; an analysis processing unit that analyzes the resistance value data based on the operation information data acquired by the data acquisition processing unit and acquires an index value for detecting a breakage of the wire; A break detection processing unit that detects a break in the wire based on the index value in the analysis processing unit. Disconnection detection device.

8. A wire breakage detection device that detects that a wire of a cable having a conductor composed of a plurality of wires and wired to an apparatus is broken due to an operation of the apparatus, a data acquisition processing unit that acquires resistance value data, which is data on the resistance value of the conductor that changes over time due to the operation of the device; an analysis processing unit that generates operation information data from the resistance value data, the operation information data being data indicating a change over time in information related to an operation of the device, analyzes the resistance value data based on the operation information data, and obtains an index value for detecting a break in the wire; A break detection processing unit that detects a break in the wire based on the index value in the analysis processing unit. Disconnection detection device.

Images