Measuring device, evaluation device for conductor strain, and disconnection detection device

Abstract

To provide a measuring device that accurately measures change of a resistance value of a conductor in a cable, an evaluation device for conductor strain and a disconnection detection device.SOLUTION: A cable resistance measuring device 1 as a measuring device comprises: an operation application mechanism 3 applying operation to a cable 2 including a conductor; and a resistance measuring instrument 4 for measuring a chronologically changing resistance value of the conductor due to the operation. The resistance measuring instrument 4 includes: a transmission side unit 4a which is connected to one end of the cable 2 and outputs an inspecting signal generated from a reference frequency signal to the conductor; and a reception side unit 4b which is constituted separately from the transmission side unit 4a and is connected to the other end of the cable 2 and measures a chronologically changing resistance value of the conductor, based on a detecting signal generated from an output signal from the conductor and the reference frequency signal.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a measuring device, a conductor strain evaluation device, and a disconnection detection device.

Background Art

[0002] For example, there are known cables to which repeated bending or / and twisting operations are applied, such as cables wired to movable parts of industrial robots. For example, in the cables used in industrial robots, sudden disconnection may cause problems such as stoppage of the production line, so it is desirable to replace the cable before most of the plurality of conductors arranged in the cable reach disconnection (that is, before the cable reaches the end of its life). Therefore, in order to determine the replacement timing of the cable, it is necessary to accurately evaluate the disconnection of the conductors included in the cable.

[0003] Note that Patent Documents 1 and 2 are available as prior art document information related to the invention of this application.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present inventors are proposing to evaluate the strain of a conductor and estimate the progress of conductor disconnection based on the resistance value of the conductor that changes according to the operation applied to the cable. In order to perform these evaluations and estimations accurately, it is desirable to accurately measure minute changes in the resistance value of the conductor.

[0006] By the way, as described above, when measuring the resistance value of a conductor that changes according to the operation applied to the cable, it is necessary to measure the resistance of the conductor while applying the operation to the cable. Therefore, with the operation of this cable, the lead wire connecting the resistance measuring device and the cable may be repeatedly bent. In such a case, due to repeated bending, strain occurs in the conductor of the lead wire and the resistance value changes, and the change in the resistance value in the lead wire becomes noise, and there are cases where the change in the resistance value of the conductor in the cable cannot be accurately measured.

[0007] Therefore, an object of the present invention is to provide a measuring device, a conductor strain evaluation device, and a disconnection detection device that can accurately measure changes in the resistance value of a conductor in a cable.

Means for Solving the Problems

[0008] The present invention aims to solve the above problems, and includes an operation applying mechanism for applying an operation to a cable having a conductor, and a resistance measuring device for measuring the resistance value of the conductor that changes in time series due to the operation. The resistance measuring device is connected to one end of the cable and includes a transmission side unit that outputs a test signal generated from a reference frequency signal to the conductor, and is configured separately from the transmission side unit and connected to the other end of the cable. It has a receiving side unit that measures the resistance value of the conductor that changes in time series based on the output signal from the conductor and the detection signal generated from the reference frequency signal.

[0009] Further, the present invention aims to solve the above problems, and provides a conductor strain evaluation device including the measurement device and a strain evaluation processing unit that evaluates the strain applied to the conductor based on the fluctuation range of the resistance value measured by the measurement device.

[0010] Further, the present invention aims to solve the above problems, and provides a disconnection detection device including the measurement device and a disconnection progress state estimation processing unit that estimates the disconnection progress state of the conductor based on the magnitude of the resistance value variation component of the operating frequency corresponding to the operation or its higher-order frequency at the resistance value measured by the measurement device.

Effect of the Invention

[0011] According to the present invention, it is possible to provide a measurement device, a conductor strain evaluation device, and a disconnection detection device that can accurately measure changes in the resistance value of a conductor in a cable.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiment for Carrying Out the Invention

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

[0014] FIG. 1 is a schematic configuration diagram showing a cable resistance measuring device 1 as a measuring device according to the present embodiment, and FIG. 2 is a diagram showing an example of a circuit diagram of the resistance measuring device 4. As shown in FIGS. 1 and 2, the cable resistance measuring device 1 includes an operation applying mechanism 3 that applies a periodic operation to the cable 2, a resistance measuring device 4, and a lead wire 5 that connects the resistance measuring device 4 and the cable 2.

[0015] (Operation applying mechanism 3) The operation applying mechanism 3 is a mechanism that applies a periodic operation to the cable 2 to be measured. In the present embodiment, the cable 2 is configured by twisting a plurality of electric wires. And the operation applying mechanism 3 is configured to apply a repeated bending operation to the cable 2 to the left and right. The operation applying mechanism 3 has a pair of cylindrical mandrels 31 provided so as to sandwich the cable 2, and is configured to apply a bending operation to the cable 2 by rotating the pair of mandrels 31. Weights 32 are respectively provided at both ends of the cable 2.

[0016] Any one of the electric wires constituting the cable 2 is the measurement target, and lead wires 5 are respectively connected to both ends of the conductor of the electric wire to be measured. The conductor of the cable 2 is composed of a plurality of strands, and is, for example, a stranded conductor formed by twisting a plurality of strands made of copper or a copper alloy.

[0017] In the motion imparting mechanism 3, the cable 2 is bent clockwise or counterclockwise at a predetermined angle (90 degrees in the figure). The motion imparted to the cable 2 by the motion imparting mechanism 3 may be, for example, a twisting motion that periodically twists the cable 2 in its circumferential direction, or a U-shaped bending motion in which the cable 2 is bent into a U shape and one end of the cable 2 is periodically slid in a predetermined stroke along the longitudinal direction of the cable at that end. Further, the motion imparted to the cable 2 may be a rocking motion that periodically rocks the cable 2. The cable 2 to be measured may be a flat cable. Note that the above-described motion imparted to the cable 2 by the motion imparting mechanism 3 does not have to be a periodic motion. Furthermore, the motion imparting mechanism 3 may be a device such as an industrial robot in which the cable 2 is wired, and the cable 2 may be imparted with a motion by causing the device to perform a predetermined motion.

[0018] (Resistance measuring device 4) The resistance measuring device 4 measures the resistance value of the conductor that changes in time series due to the motion when a predetermined motion is repeatedly applied to the cable 2. In the present embodiment, the resistance measuring device 4 is composed of two units, a transmission side unit 4a and a reception side unit 4b.

[0019] By configuring the transmission side unit 4a and the reception side unit 4b separately, it becomes possible to arrange the transmission side unit 4a near one end of the cable 2 and the reception side unit 4b near the other end of the cable 2, and it becomes possible to shorten the lead wire 5 that connects the cable 2 and the resistance measuring device 4. As a result, the resistance value of the lead wire 5 can be reduced. Further, according to the present embodiment, since it is not necessary to wire the lead wire 5 to the motion imparting portion, it is possible to suppress the influence (fluctuation of the resistance value) of the strain of the lead wire 5 caused by the motion being imparted to the conductor of the lead wire 5.

[0020] The transmitting unit 4a is connected to one end of the cable 2 and has a transmitting oscillator 41a as a signal source that outputs an inspection signal to the conductor to be measured. In the present embodiment, the resistance measuring device 4 has a reference frequency oscillator 46 that outputs a reference frequency signal to the transmitting oscillator 41a, and the reference frequency oscillator 46 is mounted on the transmitting unit 4a. The transmitting oscillator 41a consists of a variable frequency oscillator. Based on the reference frequency signal input from the reference frequency oscillator 46, it generates an inspection signal consisting of an alternating current signal of a predetermined frequency and outputs the generated inspection signal to the conductor of the cable 2 that is the measurement target. A capacitive element 45 adjusted to a capacitance that allows the inspection signal to pass through and blocks other signals is provided between the transmitting oscillator 41a and one end of the cable 2.

[0021] The inspection signal is obtained by dividing a reference frequency signal having a predetermined frequency input to the transmitting oscillator 41a by a predetermined division ratio. The frequency of the inspection signal is, for example, about several kHz. The frequency of the inspection signal may be appropriately adjusted to be different from the frequency of external noise, etc. And it is desirable that the frequency of the reference frequency signal be sufficiently higher than the frequency of the inspection signal, for example, be a frequency 1000 times or more the frequency of the inspection signal. For example, when the frequency of the reference frequency signal is 1 MHz, it is divided in the transmitting oscillator 41a into an inspection signal with a frequency of 1 kHz. The larger the division ratio in the transmitting oscillator 41a, the more the measurement accuracy can be improved.

[0022] The inspection signal output from the transmitting unit 4a is input to one end of the conductor of the cable 2 via the lead wire 5. In the present embodiment, the transmitting unit 4a is mounted on the operation imparting mechanism 3 and is configured to move together with one end of the cable 2 when an operation is imparted to the cable 2. Thereby, the lead wire 5 can be shortened, and fluctuations in the resistance value due to strain being applied to the lead wire 5 can be suppressed.

[0023] In addition, the transmission-side unit 4a is equipped with a voltage circuit 47 having a constant-voltage regulator for stabilizing the power supply voltage. The power supply to the transmission-side unit 4a is provided from the outside. However, by setting the voltage of the power supply to be sufficiently high, even if there is a change in the resistance value of the power cable used for power supply, there will be no particular problem. Therefore, there is no problem even if the power cable is arranged along the cable 2 and configured such that an operation is applied to the power cable in the same manner as the cable 2.

[0024] The receiving-side unit 4b is configured separately from the transmitting-side unit 4a and is connected to the other end of the cable 2. The receiving-side unit 4b generates a detection signal that is in the same phase and has the same frequency as the inspection signal output from the transmitting-side oscillator 41a based on the reference frequency signal input without passing through the transmitting-side oscillator 41a from the reference frequency oscillator 46 provided in the transmitting-side unit 4a, and outputs the generated detection signal to the synchronous detection circuit 42. The receiving-side unit 4b also has a synchronous detection circuit 42 that synchronously detects the output signal input from the other end of the conductor via the lead wire 5 with the detection signal input from the receiving-side oscillator 41b.

[0025] The receiving - side oscillator 41b is also a variable - frequency oscillator like the transmitting - side oscillator 41a. Based on the reference - frequency signal input from the reference - frequency oscillator 46 without passing through the transmitting - side oscillator 41a, it generates a detection signal composed of an AC signal with a predetermined frequency (in - phase and of the same frequency as the inspection signal), and outputs the generated detection signal to the synchronous - detection circuit 42. In this embodiment, since the reference - frequency oscillator 46 is mounted on the transmitting - side unit 4a, a reference - frequency signal transmission cable 6 for transmitting the reference - frequency signal without passing through the transmitting - side oscillator 41a is provided between the transmitting - side unit 4a and the receiving - side unit 4b. Since the reference - frequency signal is at a relatively high frequency, it is desirable to use a coaxial cable as the reference - frequency signal transmission cable 6. The reference - frequency signal transmission cable 6 is wired along the cable 2. Therefore, when an operation is applied to the cable 2, an operation is also applied to the reference - frequency signal transmission cable 6, resulting in a slight change in the resistance value. However, since the reference - frequency signal is a digital signal, this does not pose a particular problem. Note that one of the electric wires (such as a coaxial wire) included in the cable 2 may be used as the reference - frequency signal transmission cable 6. When the reference - frequency signal transmission cable 6 is wired along the cable 2, in order to suppress the influence on the cable 2 during the operation of the operation - applying mechanism 3, the outer diameter of the reference - frequency signal transmission cable 6 needs to be smaller than the outer diameter of the cable 2.

[0026] The synchronous - detection circuit 42 is composed of a mixer that multiplies the output signal input from the other end of the cable 2 via the lead wire 5 and the detection signal input from the receiving - side oscillator 41b for synchronous detection. A capacitive element 45 adjusted to a capacitance that can pass the output signal and block other signals is provided between the other end of the cable 2 and the synchronous - detection circuit 42.

[0027] On the receiving unit 4b, the resistance value of the conductor of the cable 2 is measured based on the magnitude of the DC component of the signal (synchronous detection signal) synchronously detected by the synchronous detection circuit 42. The receiving unit 4b further includes a low-pass filter (LPF) 43 into which the signal from the synchronous detection circuit 42 is input, and an A / D converter 44 that converts the signal from the low-pass filter 43 into a digital signal and outputs it to arithmetic units 101 and 201 (see FIGS. 4 and 6) described later. Also, the receiving unit 4b is equipped with a voltage circuit 48 having a constant voltage regulator for stabilizing the power supply voltage.

[0028] When the frequency of the detection signal is set to the same ωc as the frequency of the inspection signal, the synchronous detection circuit 42 multiplies (in other words, synchronously detects) this detection signal and the output signal from the other end of the cable 2 to generate a signal in which a signal of the DC component and a signal of the 2×ωc component are superimposed, and outputs the generated signal to the low-pass filter 43. The low-pass filter 43 blocks the signal of the 2×ωc component of the signal input from the synchronous detection circuit 42 and passes the signal of the DC component. This signal of the DC component represents the magnitude of the component of the frequency ωc. Since the magnitude of the component of the frequency ωc changes depending on the magnitude of the resistance value of the conductor to be measured, the resistance value of the conductor can be obtained from the magnitude of the obtained component of the frequency ωc. Note that the receiving unit 4b may be configured to be able to measure changes in the electrical characteristics (for example, capacitance and self-inductance) of the cable 2 other than the resistance value of the conductor.

[0029] If the transmission-side unit 4a and the reception-side unit 4b are configured separately and a reference frequency oscillator 46 having a predetermined jitter (a slight fluctuation in the oscillation frequency over time) is provided in the reception-side unit 4b, the reference frequency signal output from the reference frequency oscillator 46 is input to the transmission-side oscillator 41a provided in the transmission-side unit 4a, a test signal is generated by the transmission-side oscillator 41a, and the generated test signal is input to the synchronous detection circuit 42 of the reception-side unit 4b via the cable 2. At this time, the paths (propagation paths) through which the reference frequency signal and the test signal generated thereby propagate become longer, and the time (propagation time) required for these signals to propagate through the entire path also becomes longer. Therefore, when the length of the cable 2 to be measured is long and the length of the cable 6 for transmitting the reference frequency signal is also as long as that of the cable 2, the reference frequency signal output from the reception-side unit 4b is generated as a test signal by the transmission-side oscillator 41a, and the propagation time from when the test signal is input to the synchronous detection circuit 42 of the reception-side unit 4b from the other end of the cable 2 as an output signal until the reference frequency signal from the reference frequency oscillator 46 is generated as a detection signal by the reception-side oscillator 41b and the detection signal is input to the synchronous detection circuit 42, a time difference is likely to occur in the signal derived from the reference frequency oscillator by the time required to propagate through the entire path. When such a time difference occurs, since the reference frequency oscillator 46 has jitter (a slight fluctuation in the oscillation frequency over time), a deviation occurs between the frequencies of the signals input to the synchronous detection circuit 42, and there arises a problem that the measurement accuracy deteriorates.

[0030] On the other hand, in the present invention, by configuring the transmission-side unit 4a and the reception-side unit 4b separately and providing the reference frequency oscillator 46 in the transmission-side unit 4a, it becomes difficult for the above-described difference to occur in the respective propagation times of the output signal input to the synchronous detection circuit 42 via the cable 2 to be measured and the detection signal input to the synchronous detection circuit 42 without passing through the cable 2. Therefore, it becomes difficult for a frequency deviation to occur in the signals subjected to synchronous detection in the synchronous detection circuit 42, and the measurement accuracy can be improved.

[0031] (Conductor Strain Evaluation Device 100) Next, the conductor strain evaluation device 100 using the cable resistance measuring device 1 will be described. FIG. 3 is a schematic configuration diagram of the conductor strain evaluation device 100. As shown in FIG. 3, the conductor strain evaluation device 100 includes a cable resistance measuring device 1 and an arithmetic unit 101.

[0032] The arithmetic unit 101 has a control unit 102 and a storage unit 103. The control unit 102 is equipped with a data acquisition processing unit 104, an operating frequency estimation processing unit 105, a cycle start point setting processing unit 106, and a strain evaluation processing unit 107. These data acquisition processing unit 104, operating frequency estimation processing unit 105, cycle start point setting processing unit 106, and strain evaluation processing unit 107 are realized by appropriately combining arithmetic elements such as a CPU, memories such as a RAM and a ROM, software, an interface, a storage device, etc. The arithmetic unit 101 is configured by, for example, a personal computer. Note that the arithmetic unit 101 is not limited to this, and may be, for example, a server device.

[0033] In addition, a display 108 and an input device 109 are connected to the arithmetic unit 101. Note that the display 108 and the input device 109 do not necessarily need to be wired-connected to the arithmetic unit 101, and may be wirelessly connected. In this case, the display 108 and the input device 109 may be configured by a mobile terminal such as a smartphone or a tablet.

[0034] The data acquisition processing unit 104 acquires measurement data from the resistance measuring device 4 (reception side unit 4b) of the cable resistance measuring device 1 and stores it in the storage unit 103 as resistance value data 110.

[0035] When the operating frequency, which is the frequency corresponding to the period of the operation applied to cable 2, is unknown, the operating frequency estimation processing unit 105 estimates the operating frequency based on the resistance value data 110 measured by the resistance measuring device 4. When the operating frequency (or operating period) is known, or when the operating frequency can be obtained from information from the operation applying mechanism 3 or the like, the operating frequency estimation processing unit 105 can be omitted.

[0036] The operating frequency estimation processing unit 105 performs a frequency analysis of the resistance value data 110 (i.e., the resistance value data of the conductor that changes in time series), and estimates the operating frequency based on the result of the frequency analysis. More specifically, a frequency analysis of the resistance value data 110 is performed, and the magnitude of the signal (i.e., the amplitude of the resistance value fluctuation or the resistance value fluctuation width) is obtained for each component of each frequency. In the analysis result of the obtained frequency analysis, the operating frequency component and its higher-order frequency components that are n times (n is a natural number of 2 or more) the operating frequency component are larger than other frequency components. Therefore, it is advisable to extract the frequency with a relatively large signal magnitude from the analysis result of the frequency analysis, and estimate the smallest (lowest-order) frequency among the extracted frequencies as the operating frequency. Note that frequency components near 0 Hz (for example, 0.2 Hz or less) with a large influence of noise should be excluded. Also, even if the frequency has a large signal magnitude, if the signal magnitude at a frequency that is n times the frequency is small and no higher-order frequency component is generated, the frequency may be excluded as noise. The operating frequency estimated by the operating frequency estimation processing unit 105 is stored in the storage unit 103 as the operating frequency data 111.

[0037] The cycle start point setting processing unit 106 is for setting the start point of the operation cycle in the operation applied to the cable 2. Therefore, when the start point of the cycle is known (for example, when the start point of the operation cycle can be obtained from information from the operation applying mechanism 3, etc.), the cycle start point setting processing unit 106 can be omitted. The cycle start point setting processing unit 106 extracts the component of the operation frequency estimated by the operation frequency estimation processing unit 105 from the resistance value data 110 in order to exclude the influence of noise, and sets the start point of the cycle based on the temporal change of the extracted operation frequency component. The start point of the cycle set by the cycle start point setting processing unit 106 is stored in the storage unit 103 as the cycle start point data 112.

[0038] The strain evaluation processing unit 107 evaluates the strain based on the variation range of the resistance value of the conductor that changes in time series measured by the cable resistance measuring device 1. However, when using the variation range of the resistance value only in the section corresponding to one operation, the influence of noise becomes large, and it is conceivable that sufficient evaluation accuracy cannot be obtained. Therefore, in the present embodiment, the strain evaluation processing unit 107 divides the resistance value of the conductor that changes in time series for each operation cycle, and averages the change in the resistance value of each divided cycle for each elapsed time from the start point of the cycle, and obtains the change in the resistance value for one averaged cycle. The strain is evaluated based on the variation range of the resistance value in the change in the resistance value for one averaged cycle.

[0039] More specifically, as shown in FIG. 4, the strain evaluation processing unit 107 first divides the resistance value data 110 for each section corresponding to one operation (that is, divides the resistance value data 110 for each operation cycle) based on the operation frequency estimated by the operation frequency estimation processing unit 105 and the start point of the cycle set by the cycle start point setting processing unit 106. Hereinafter, the divided resistance value data 110 is referred to as divided resistance value data 113. Each obtained divided resistance value data 113 is stored in the storage unit 103.

[0040] Then, the strain evaluation processing unit 107 overlaps and averages a plurality of divided resistance value data 113 to obtain resistance value data for one averaged section (one cycle). Hereinafter, the resistance value data for this averaged one section (one cycle) is referred to as averaged resistance value data 114. When averaging, it is advisable to add up all the resistance values at the same time (elapsed time from the start of the cycle) in each section and divide by the number of sections added together for averaging. The obtained averaged resistance value data 114 is stored in the storage unit 103.

[0041] Then, the strain evaluation processing unit 107 obtains, as the strain equivalent amount, the fluctuation range of the resistance value in the obtained averaged resistance value data 114, that is, the value obtained by subtracting the minimum value from the maximum value of the resistance value in the averaged resistance value data 114. This strain equivalent amount is an amount proportional to the strain applied to the conductor, and it is possible to evaluate the strain applied to the conductor from this strain equivalent amount. Note that the strain evaluation processing unit 107 may be configured to calculate the strain applied to the conductor from the strain equivalent amount. The obtained strain equivalent amount is stored in the storage unit 103 as strain equivalent amount data 115.

[0042] Although not shown in the figure, the arithmetic device 101 may be equipped with a life prediction unit that predicts the number of operating times of the cable 2 until the cable 2 reaches the end of its life based on the strain equivalent amount obtained by the strain evaluation processing unit 107. For example, the relationship between the strain equivalent amount and the number of operating times of the cable 2 until the cable 2 reaches the end of its life can be obtained in advance through actual measurement, and based on this relationship, the life prediction unit can be configured to predict the number of operating times of the cable 2 until the cable 2 reaches the end of its life.

[0043] According to the conductor strain evaluation device 100, it becomes possible to easily evaluate the strain of the conductor in the cable 2, and based on the evaluated strain, it becomes possible to evaluate the number of operating times until the cable 2 reaches the end of its life in a short time. Although the change in the resistance value of the conductor due to strain is minute, by using the cable resistance measurement device 1 according to the present embodiment, the error due to the change in the resistance value of the lead wire 5 can be suppressed, and the accuracy of strain evaluation can be improved. Furthermore, by using the averaged resistance value data 114 obtained by averaging the divided resistance value data 113 and obtaining the fluctuation range of the resistance value in this averaged resistance value data 114 as the strain equivalent amount, the influence of noise can be suppressed, and strain can be accurately evaluated.

[0044] (Open circuit detection device 200) Next, the open circuit detection device 200 using the cable resistance measurement device 1 will be described. FIG. 5 is a schematic configuration diagram of the open circuit detection device 200. As shown in the figure, the open circuit detection device 200 includes a cable resistance measurement device 1 and an arithmetic device 201.

[0045] When a periodic operation is applied to the conductor in a state where a strand of the conductor is broken, the broken portion will periodically repeat approaching and separating in response to the operation, and a change in the resistance value will occur at the operation period, which is the period of the applied operation, or a period that is an integer multiple of the operation period. Therefore, by using the cable resistance measurement device 1 to measure the resistance value of the conductor that changes over time, and monitoring the magnitude of the component of the operation frequency, which is the frequency corresponding to the operation period, or the component of its higher-order frequency, in the obtained resistance value data 210, it becomes possible to detect that a strand of the conductor is broken (that is, the progress of the conductor break). By using this method, for example, it becomes possible to accurately detect the break of the strand excluding the influence of factors such as the change in the resistance value due to temperature, and it becomes possible to detect, for example, at the initial stage of break where one to several strands are broken.

[0046] The arithmetic unit 201 includes a control unit 202 and a storage unit 203. The control unit 202 is equipped with a data acquisition processing unit 204, a frequency analysis processing unit 205, a disconnection progress state estimation processing unit 206, and an alarm processing unit 207. These data acquisition processing unit 204, frequency analysis processing unit 205, disconnection progress state estimation processing unit 206, and alarm processing unit 207 are realized by appropriately combining arithmetic elements such as a CPU, memories such as RAM and ROM, software, interfaces, storage devices, etc. The arithmetic unit 201 is composed of, for example, a personal computer. Note that the arithmetic unit 201 is not limited to this, and may be, for example, a server device.

[0047] In addition, a display 208 and an input device 209 are connected to the arithmetic unit 201. Note that the display 208 and the input device 209 do not necessarily need to be wired-connected to the arithmetic unit 201, and may be wirelessly connected. In this case, the display 208 and the input device 209 may be composed of, for example, a mobile terminal such as a smartphone or a tablet.

[0048] The data acquisition processing unit 204 acquires measurement data from the resistance measuring device 4 (reception side unit 4b) of the cable resistance measuring device 1, and stores it in the storage unit 203 as resistance value data 210.

[0049] The frequency analysis processing unit 205 performs frequency analysis on the resistance value data 210. The result of the frequency analysis is stored in the storage unit 203 as frequency analysis data 211. Note that frequency analysis means analyzing the magnitude of each frequency component included in the resistance value data 210 and obtaining frequency analysis data 211 which is data obtained by extracting the magnitude of the component for each frequency. Then, the frequency analysis processing unit 205 extracts a resistance value variation component of an operating frequency or a higher-order frequency that is n times (n is a natural number of 2 or more) the operating frequency from the frequency analysis data 211 obtained by frequency analysis. It is advisable to determine which frequency's resistance value variation component to extract according to the operation applied by the operation application mechanism 3, etc., and it is preferable to conduct experiments in advance and set based on the experimental results.

[0050] The disconnection progress state estimation processing unit 206 estimates the disconnection progress state by comparing the resistance value fluctuation component extracted by the frequency analysis processing unit 205 with a preset threshold value. In the present embodiment, the disconnection progress state estimation processing unit 206 determines whether the magnitude of the resistance value fluctuation component extracted by the frequency analysis processing unit 205 is greater than the preset threshold value. The determination result is stored in the storage unit 203 as determination data 212. As the preset threshold value, for example, it is set to the magnitude of the resistance value fluctuation component at the operating frequency or its higher-order frequency when x (x is an integer of 1 or more) of the plurality of strands constituting the conductor are disconnected. By appropriately setting the threshold value used for determination according to the occurrence of disconnection in the strands, it is possible to estimate that a desired disconnection progress state has been reached, for example, at the stage of the initial occurrence of disconnection or at the stage where the disconnection has further progressed from the initial disconnection (that is, when one of the plurality of strands is disconnected). Regarding the specific value to be set for the threshold value, it is preferable to conduct experiments in advance and set it based on the experimental results.

[0051] When the disconnection progress state estimation processing unit 206 determines that a desired disconnection progress state has been reached, the alarm processing unit 207 issues an alarm to an administrator or the like. The alarm issued by the alarm processing unit 207 may be, for example, an alarm by light or sound, or may be performed by an alert display on the display 208 or a notification using an e-mail or the like.

[0052] According to the disconnection progress state estimation processing unit 206, by using the cable resistance measuring device 1, it is possible to suppress the change in the resistance value of the conductor due to the strain of the lead wire 5 and accurately detect the disconnection progress state of the cable 2.

[0053] (Operations and Effects of the Embodiment) As described above, in the cable resistance measuring device 1 according to the present embodiment, the resistance measuring instrument 4 is configured by dividing it into a transmission side unit 4a and a reception side unit 4b. As a result, each unit 4a, 4b can be arranged near the end of the cable 2 to shorten the lead wire 5, and the resistance value of the lead wire 5 can be reduced. Further, for example, since it is not necessary to wire the lead wire 5 to the operation imparting mechanism 3 along the cable 2, it is possible to suppress the influence of the strain generated in the lead wire 5 due to the operation of the operation imparting mechanism 3 and accurately measure the change in the resistance value of the conductor. Therefore, by using the cable resistance measuring device 1 for the conductor strain evaluation device 100 or the disconnection detection device 200, it is possible to accurately evaluate the strain and estimate the progress state of the disconnection.

[0054] (Modification example) In the above embodiment, the reference frequency oscillator 46 is mounted on the transmission side unit 4a. However, the present invention is not limited to this, and the reference frequency oscillator 46 may be mounted on the reception side unit 4b. In this case, the reference frequency signal will be transmitted from the reception side unit 4b to the transmission side unit 4a.

[0055] Further, in the above embodiment, the reference frequency signal is transmitted between the transmission side unit 4a and the reception side unit 4b by wired communication using the reference frequency signal transmission cable 6. However, the present invention is not limited to this, and the reference frequency signal may be transmitted between the transmission side unit 4a and the reception side unit 4b by wireless communication. For example, as shown in FIG. 6, by providing a transmitter 71 that transmits a reference frequency signal to the transmission side unit 4a and a receiver 72 that receives a reference frequency signal to the reception side unit 4b, it is possible to transmit a reference frequency signal by wireless communication.

[0056] Furthermore, the reference frequency oscillator 46 may not be mounted on both the transmission-side unit 4a and the reception-side unit 4b. In this case, it is preferable that the reference frequency oscillator 46 and the transmission-side unit 4a and the reception-side unit 4b are configured to transmit a reference frequency signal by wireless communication or wired communication. For example, when transmitting the reference frequency signal wirelessly, as shown in FIG. 7, the reference frequency signal from the reference frequency oscillator 46 is transmitted by the transmitter 71, and the receiver 72 provided in the transmission-side unit 4a and the reception-side unit 4b receives the reference frequency signal. Using the configuration of FIG. 7, for example, a clock output obtained by GPS (Global Positioning System) may be used as the reference frequency signal.

[0057] Also, in the above embodiment, an alternating current inspection signal is used, but a direct current signal may be used as the inspection signal. In this case, since it is not necessary to synchronize between the transmission-side unit 4a and the reception-side unit 4b, the reference frequency oscillator 46 and the reference frequency signal transmission cable 6 can be omitted.

[0058] (Summary of Embodiment) Next, the technical idea grasped from the above-described embodiments will be described by referring to the reference numerals and the like in the embodiments. However, each reference numeral and the like in the following description are not limited to the members and the like that specifically show the components in the claims in the embodiments.

[0059] [1] A measurement device (1) comprising: an operation imparting mechanism (3) for imparting an operation to a cable (2) having a conductor; and a resistance measuring device (4) for measuring a resistance value of the conductor that changes in time series by the operation, wherein the resistance measuring device (4) is connected to one end of the cable (2), and includes a transmission-side unit (4a) that outputs an inspection signal generated from a reference frequency signal to the conductor, and a reception-side unit (4b) that is configured separately from the transmission-side unit (4a), is connected to the other end of the cable (2), and measures the resistance value of the conductor that changes in time series based on an output signal from the conductor and a detection signal generated from the reference frequency signal.

[0060] [2] The resistance measuring device (4) has a reference frequency oscillator (46) that outputs the reference frequency signal. The transmission side unit (4a) has a transmission side oscillator (41a) that outputs the inspection signal composed of an alternating current signal of a predetermined frequency based on the reference frequency signal. The reception side unit (4b) has a reception side oscillator (41b) that outputs the detection signal having the same phase and the same frequency as the inspection signal based on the reference frequency signal, and a synchronous detection circuit (42) that synchronously detects the output signal output from the other end of the conductor with the detection signal. The measuring device (1) according to [1].

[0061] [3] The reference frequency oscillator (46) is mounted on either the transmission side unit (4a) or the reception side unit (4b), and further has a reference frequency signal transmission cable (6) that transmits the reference frequency signal between the transmission side unit (4a) and the reception side unit (4b). The measuring device (1) according to [2].

[0062] [4] The reference frequency oscillator (46) is mounted on either the transmission side unit (4a) or the reception side unit (4b), and is configured to transmit the reference frequency signal by wireless communication between the transmission side unit (4a) and the reception side unit (4b). The measuring device (1) according to [2].

[0063] [5] The reference frequency oscillator (46) is not mounted on the transmission side unit (4a) and the reception side unit (4b), and is configured to transmit the reference frequency signal between the reference frequency oscillator (46), the transmission side unit (4a), and the reception side unit (4b) by wireless communication or wired communication. The measuring device (1) according to [2].

[0064] [6] A strain evaluation device (100) including the measuring device (1) according to any one of [1] to [5], and a strain evaluation processing unit (107) that evaluates the strain applied to the conductor based on the variation range of the resistance value measured by the measuring device (1).

[0065] [7][1] to any one of [5] of the measuring device (1), and a disconnection progress state estimation processing unit (206) that estimates the disconnection progress state of the conductor based on the magnitude of the resistance value variation component of the operating frequency corresponding to the operation or its higher-order frequency at the resistance value measured by the measuring device (1). A disconnection detection device (200) comprising:

[0066] (Appendix) As described above, the embodiments of the present invention have been described. However, the embodiments described above do not limit the invention according to the claims. Also, it should be noted that not all combinations of features described in the embodiments are essential means for solving the problems of the invention. Further, the present invention can be implemented by appropriately modifying it without departing from its gist.

Explanation of Reference Numerals

[0067] 1... Cable resistance measuring device (measuring device) 2... Cable 3... Operation applying mechanism 4... Resistance measuring instrument 4a... Transmission side unit 4b... Reception side unit 41a... Transmission side oscillator 41b... Reception side oscillator 42... Synchronous detection circuit 46... Reference frequency oscillator 5... Lead wire 6... Cable for transmitting reference frequency signal

Claims

1. An operation imparting mechanism for imparting an operation to a cable having a conductor, and a resistance measuring device for measuring the resistance value of the conductor that changes in time series by the operation, comprising: The resistance measuring device A transmission side unit connected to one end of the cable and outputting a test signal generated from a reference frequency signal to the conductor, A reception side unit configured separately from the transmission side unit, connected to the other end of the cable, and measuring the resistance value of the conductor that changes in time series based on the output signal from the conductor and a detection signal generated from the reference frequency signal. A measuring device.

2. The resistance measuring device has a reference frequency oscillator that outputs the reference frequency signal, The transmission side unit has a transmission side oscillator that outputs the test signal composed of an AC signal of a predetermined frequency based on the reference frequency signal, The reception side unit has a reception side oscillator that outputs the detection signal in the same phase and at the same frequency as the test signal based on the reference frequency signal, and a synchronous detection circuit that synchronously detects the output signal output from the other end of the conductor with the detection signal. The measuring device according to claim 1.

3. The reference frequency oscillator is mounted on either the transmission side unit or the reception side unit, The measuring device according to claim 2, further comprising a reference frequency signal transmission cable for transmitting the reference frequency signal between the transmission side unit and the reception side unit. The measuring device according to claim 2.

4. The reference frequency oscillator is mounted on either the transmission side unit or the reception side unit, The measuring device according to claim 2, configured to transmit the reference frequency signal by wireless communication between the transmission side unit and the reception side unit. The measuring device according to claim 2.

5. The reference frequency oscillator is not mounted on the transmission side unit and the reception side unit, The reference frequency oscillator is configured to transmit the reference frequency signal by wireless communication or wired communication between the reference frequency oscillator and the transmission side unit and the reception side unit. The measuring device according to claim 2.

6. The measuring device according to any one of claims 1 to 5, and A strain evaluation processing unit for evaluating the strain applied to the conductor based on the variation range of the resistance value measured by the measuring device. A conductor strain evaluation device.

7. The measuring device according to any one of claims 1 to 5, and Based on the magnitude of the resistance value fluctuation component of the operating frequency corresponding to the operation or its higher-order frequency at the resistance value measured by the measurement device, a disconnection progress state estimation processing unit that estimates the disconnection progress state of the conductor, and A disconnection detection device.

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