Cable for detection and detection system

Abstract

To provide a cable for detection that can properly detect deformation.SOLUTION: A cable for detection comprises a conductor wire, an insulation layer provided on an outer peripheral side of the conductor wire, and a shield layer provided on an outer peripheral side of the insulation layer. The insulation layer has a plurality of pores formed in a circumference of the conductor wire.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to sensing cables and sensing systems. [Background technology]

[0002] In general, a coaxial cable for signal transmission includes a conductor wire, an insulating layer surrounding the side surfaces of the conductor wire, and a shielding layer covering the side surfaces of the insulating layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-138285 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a coaxial cable, a configuration capable of suppressing a change in the distance between a conductor wire and a shield layer is often adopted. This is because when the distance between the conductor wire and the shield layer changes due to deformation of the coaxial cable, the impedance of the coaxial cable changes partially, causing reflection loss in the coaxial cable and deteriorating transmission characteristics.

[0005] The inventors of the present application focused on the fact that the impedance of a coaxial cable changes partially due to deformation of the coaxial cable, and conducted research into attaching a coaxial cable to an object to be detected and using it as a sensor for detecting distortion or deformation of the object to be detected or for detecting external forces acting on the object to be detected. In the process, the following embodiments have been completed. [Means for solving the problem]

[0006] The detection cable according to the present disclosure includes a conductor wire, an insulating layer provided on an outer periphery of the conductor wire, and a shielding layer provided on the outer periphery of the insulating layer. The insulating layer has a plurality of holes provided around the conductor wire. Effect of the Invention

[0007] According to the present disclosure, it is possible to obtain a detection cable that can be used as a sensor capable of appropriately detecting deformation. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating an example of an overall configuration of a detection system according to the first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of the detection cable taken along a plane perpendicular to the longitudinal direction thereof. [Diagram 3] FIG. 3 is a block diagram showing a detection device. [Figure 4A] FIG. 4A is a cross-sectional view showing an example of a sheet-like member in a state where no external force is applied. [Figure 4B] FIG. 4B is a cross-sectional view showing an example of a sheet-like member in a state where an external force is applied. [Figure 5A] FIG. 5A is a diagram showing an example of data indicating the relationship between the amount of reflection and the compression rate of the detection cable. [Figure 5B] FIG. 5B is a diagram showing an example of data showing the relationship between the compression rate of the detection cable and the external force acting on the outer surface. [Figure 6] FIG. 6 is a diagram illustrating an example of an overall configuration of a detection system according to the second embodiment. [Figure 7] FIG. 7 is a cross-sectional view taken along a plane perpendicular to the longitudinal direction of the power cable. [Figure 8A] FIG. 8A is a diagram showing a power cable in a bent state after being stretched. [Figure 8B] FIG. 8B is an example of a cross-sectional view of the detection cable at the bent portion in FIG. 8A. [Figure 9]FIG. 9 is a cross-sectional view of a detection cable according to a modified example taken along a plane perpendicular to the longitudinal direction. [Figure 10] FIG. 10 is a diagram showing the results of computer simulation of the cross-sectional state of the deformed portion when the experimental example of the detection cable is subjected to compressive deformation. [Figure 11] FIG. 11 is a graph showing the relationship between the compression ratio and the impedance at the deformed portion of the detection cable. [Figure 12A] FIG. 12A is a graph showing the relationship between the frequency of an input signal and the amount of reflection of a reflected signal when the input signal is applied to a detection cable. [Figure 12B] FIG. 12B is a graph showing the relationship between the frequency of an input signal and the amount of reflection of a reflected signal when the input signal is applied to a detection cable when an actual detection cable is deformed. [Figure 13] FIG. 13 is a diagram showing the results of computer simulation of the cross-sectional state of the deformed portion when the detection cables of Experimental Examples 1 to 4 are subjected to compressive deformation. [Figure 14A] FIG. 14A is a graph showing the relationship between compressibility and crushing load. [Figure 14B] FIG. 14B is a graph in which a portion of the vertical axis of the graph in FIG. 14A is enlarged. [Figure 15A] FIG. 15A is a graph showing the relationship between the radius of curvature and the aspect ratio of the detection cable. [Figure 15B] FIG. 15B is a graph showing the relationship between the radius of curvature of the detection cable and the amount of change ΔZ. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First, the contents of the embodiment will be listed and described. [Overview of the embodiment]

[0010] (1) The present disclosure provides a detection cable comprising a conductor wire, an insulating layer provided on an outer periphery of the conductor wire, and a shielding layer provided on the outer periphery of the insulating layer, the insulating layer having a plurality of voids provided around the conductor wire.

[0011] According to the above configuration, when deformation occurs in a portion of the longitudinal direction of the detection cable due to radial compression or bending, the multiple voids are crushed, causing large deformation in the insulating layer. This causes a large change in the distance between the conductor wire and the shield layer at the deformed portion of the detection cable, and allows a large change in the impedance of the deformed portion of the detection cable. When the impedance at the deformed portion of the detection cable changes significantly, the reflection amount of the reflected signal when a predetermined input signal is applied to the detection cable also changes significantly. Therefore, by detecting the reflection amount of the reflected signal when an input signal is applied to the detection cable, the deformation of the detection cable can be appropriately detected. In other words, according to the above configuration, since the insulating layer has a plurality of holes, when the detection cable is deformed, the plurality of holes are crushed, so that the insulating layer can be significantly deformed, thereby significantly changing the impedance of the deformed portion, and significantly changing the amount of reflection of the reflected signal when an input signal is applied to the deformed detection cable. As a result, the detection cable according to this embodiment can be used as a sensor that can detect deformation of itself and deformation of a detection object to which the detection cable is attached with high sensitivity and appropriateness.

[0012] (2) In the detection cable described above in (1), the plurality of holes may have a tubular shape extending along a longitudinal direction of the conductor wire. In this case, a plurality of holes can be provided uniformly in the longitudinal direction of the conductor wire.

[0013] (3) In the detection cable of (1) or (2) above, a ratio of a cross-sectional area of ​​the plurality of holes to a cross-sectional area of ​​the insulating layer may be 30% or more and 80% or less. If the cross-sectional area ratio of the multiple holes is less than 30%, when the detection cable is deformed, the multiple holes may not be crushed sufficiently in the deformed portion. Also, if the cross-sectional area ratio of the multiple holes is more than 80%, the strength required for the detection cable may be insufficient. By setting the cross-sectional area ratio of the multiple holes to be 30% or more and 80% or less, it is possible to obtain holes that can be appropriately crushed by deformation of the detection cable.

[0014] (4) In the detection cable according to any one of the above (1) to (3), the insulating layer may have a Young's modulus of 5 MPa or more and 260 MPa or less. If the Young's modulus of the insulating layer is less than 5 MPa, the strength required for the detection cable may be insufficient.If the Young's modulus of the insulating layer is more than 260 MPa, when the detection cable is deformed, the degree of crushing of the multiple pores in the deformed portion may not be sufficient. By setting the Young's modulus of the insulating layer to 5 MPa or more and 260 MPa or less, it is possible to obtain pores that can be appropriately crushed by deformation of the detection cable.

[0015] (5) In the detection cable according to at least one of the above (1) to (4), the insulating layer may be made of a rubber material having insulating properties.

[0016] (6) In the detection cable according to at least one of (1) to (4) above, the insulating layer may be made of a resin material containing low-density polyethylene. These materials have a lower Young's modulus than polytetrafluoroethylene, which is generally used for the insulating layer of a detection cable, and therefore can be suitably used as the material for the insulating layer having voids that are appropriately crushed by deformation of the detection cable.

[0017] (7) In addition, in at least one of the detection cables (1) to (6) above, the outer diameter may be 0.3 mm or more and 1.0 mm or less. If the outer diameter is smaller than 0.3 mm, the amount of deformation of the insulation layer due to the collapse of the pores accompanying deformation will be small, and there is a risk that the deformation of the detection cable cannot be detected sufficiently.If the outer diameter is larger than 1.0 mm, there is a risk that the detection cable will be hindered from being attached to the object to be detected for deformation. By setting the outer diameter to be equal to or greater than 0.3 mm and equal to or less than 1.0 mm, the detection cable can be suitably used as a sensor that can appropriately detect deformation of the detection cable itself and deformation of the object to which the detection cable is attached.

[0018] (8) From another viewpoint, the present disclosure is a detection system. The detection system includes a detection cable and a detection device that detects a reflection amount of a reflected signal when an input signal is applied to the detection cable. The detection cable includes a conductor wire, an insulating layer provided on the outer periphery of the conductor wire, and a shielding layer provided on the outer periphery of the insulating layer. The insulating layer has a plurality of holes provided around the conductor wire. According to this configuration, it is possible to appropriately detect the deformation of the detection cable and the deformation of the detection object based on the amount of reflection of the input signal.

[0019] (9) In the detection system of (8) above, the detection device may include a signal source that provides the input signal to the conductor wire, and a processing device that executes a process of detecting the amount of reflection and a process of calculating the amount of deformation of the detection cable based on the amount of reflection. In this case, the amount of deformation of the detection cable can be obtained based on the amount of reflection of the reflected signal.

[0020] [Details of the embodiment] Hereinafter, preferred embodiments will be described with reference to the drawings. At least a part of each of the embodiments described below may be combined in any manner.

[0021] [Regarding the detection system according to the first embodiment] FIG. 1 is a diagram illustrating an example of an overall configuration of a detection system according to the first embodiment. In FIG. 1, a detection system 1 has a function of detecting pressure (external force) acting on an artificial skin of a robot or the like.

[0022] The detection system 1 includes a detection cable 2 and a detection device 4 . The detection cable 2 is attached to a sheet-like member 6 . The sheet-like member 6 is made of an elastic material and is used for artificial skin of a robot, etc. The sheet-like member 6 has an outer surface 6a. The outer surface 6a is the surface that is exposed to the outside when the sheet-like member 6 is attached to the surface of the robot. The sheet-like member 6 is elastically deformable by an external force acting on the outer surface 6a.

[0023] The detection cable 2 is inserted into a hole 6 b inside the sheet-like member 6 . The outer circumferential surface of the detection cable 2 is in contact with the hole 6b. Therefore, when the sheet-shaped member 6 is elastically deformed by an external force, the detection cable 2 is also deformed in accordance with the deformation of the sheet-shaped member 6. The detection cable 2 is attached to a detection object such as a sheet-like member 6, and is used as a sensor for detecting deformation of the detection object or detecting an external force. The detection cable 2 has a basic structure as a coaxial cable. The structure of the detection cable 2 will be described in detail later.

[0024] The detection device 4 has a function of determining the amount of deformation of the detection cable 2, and determining the external force acting on the outer surface 6a of the sheet-like member 6 (or the detection cable 2). The detection device 4 is connected to a first end 2a of the detection cable 2 via a line 7. The first end 2a is one of the two ends of the detection cable 2. The second end 2b is the end of the detection cable 2 opposite the first end 2a. A terminator 3 is connected to the second end 2b via a line 5. The terminator 3 is a resistor having a resistance value according to the characteristic impedance of the detection cable 2, and terminates the second end 2b.

[0025] [Regarding detection cable 2] FIG. 2 is a cross-sectional view of the detection cable 2 taken along a plane perpendicular to the longitudinal direction thereof. The outer shape of the detection cable 2 is approximately circular. The detection cable 2 includes a conductor wire 12, an insulating layer 14, a shield layer 16, and a coating layer 18. The conductor wire 12 is located at the radial center of the detection cable 2. The conductor wire 12, the insulating layer 14, the shield layer 16, and the coating layer 18 are layered in order from the radial center of the detection cable 2 toward the radial outside.

[0026] The conductor wire 12 is a linear member formed of a conductor such as copper, aluminum, etc. The conductor wire 12 may be a single strand, or a stranded wire in which a plurality of strands are twisted together. The insulating layer 14 is provided on the outer periphery of the conductor wire 12. The insulating layer 14 is interposed between the conductor wire 12 and the shield layer 16. The insulating layer 14 insulates the conductor wire 12 from the shield layer 16. The insulating layer 14 is made of an insulating rubber material or an insulating resin material. The shield layer 16 is provided on the outer periphery of the insulating layer 14. The shield layer 16 is interposed between the insulating layer 14 and the covering layer 18. The shield layer 16 is made of a conductor. The shield layer 16 is grounded. The shield layer 16 is made of aluminum foil or a braid. The braid is a structure obtained by weaving thin wires of a conductor such as copper or aluminum into a mesh shape. The liquid-permeable outer conductor 24 is obtained by forming the braid into a cylindrical shape.

[0027] The covering layer 18 is provided on the outer circumferential side of the shielding layer 16. The covering layer 18 is provided along the outer circumferential surface of the shielding layer 16. The covering layer 18 covers the above-mentioned components, thereby protecting the components constituting the detection cable 2 from the external environment. The covering layer 18 is formed of, for example, polyvinyl chloride, polyethylene terephthalate, or the like. The outer surface of the covering layer 18 is a contact surface that comes into contact with the hole 6b of the sheet-shaped member 6, which is the object to be detected. Stress accompanying the deformation of the sheet-shaped member 6 acts on the detection cable 2 through the outer surface of the covering layer 18. This stress causes the detection cable 2 to deform in accordance with the deformation of the sheet-shaped member 6.

[0028] Furthermore, the insulating layer 14 of the present embodiment includes a base 22 and a plurality of holes (gaps) 20. The base 22 is formed of an insulating rubber material or an insulating resin material. The insulating rubber material includes rubber compositions mainly composed of silicone rubber, fluororubber, butyl rubber, ethylene propylene rubber, etc. These rubber compositions have high insulating properties and a suitably low Young's modulus, and are therefore suitable for use as the insulating layer 14. The insulating resin material includes a resin composition mainly composed of low-density polyethylene. The resin composition mainly composed of low-density polyethylene has an appropriately low Young's modulus and is therefore suitable for use as the insulating layer 14. "Low density polyethylene" means polyethylene with a density of 0.870 g / cm 3 More than 0.930g / cm 3 This refers to polyethylene less than 100 mm. In the present embodiment, the term "main component" refers to the component that accounts for the largest percentage by mass when the total of the constituent components is 100% by mass, for example, a component that is contained in an amount of 50% by mass or more.

[0029] The insulating resin material also includes a resin composition mainly composed of polytetrafluoroethylene (PTFE). The Young's modulus of the resin composition mainly composed of PTFE is relatively high. However, since the insulating layer 14 of the present embodiment contains a plurality of pores 20, it is possible to suppress the rigidity of the resin composition mainly composed of PTFE (base 22) from hindering the deformation of the insulating layer 14.

[0030] In this embodiment, six holes 20 are provided in the cross section of the detection cable 2. The six holes 20 are provided at equal intervals in the circumferential direction around the conductor wire 12. Thus, the holes 20 are provided so as to surround the conductor wire 12. Each of the six holes 20 has a cylindrical shape extending along the longitudinal direction of the conductor wire 12 . As a result, the holes 20 are uniformly provided in the longitudinal direction of the conductor wire 12 .

[0031] [Regarding detection device 4] FIG. 3 is a block diagram showing the detection device 4. The detection device 4 has a function of applying an input signal to the detection cable 2 and detecting the reflection amount of a reflected signal relative to the input signal. The detection device 4 has a signal source 9, a directional coupler 8, and a processing device 10. The signal source 9 has a function of outputting an input signal to be provided to the first end 2a of the detection cable 2. The line 7 connects the signal source 9 and the first end 2a of the detection cable 2. The input signal is a sine wave having a frequency of several MHz to approximately 100 MHz. The directional coupler 8 is provided on the line 7. The directional coupler 8 provides the reflected signal propagating on the line 7 to the processing device 10. The processing unit 10 is also provided with an input signal from a signal source 9 .

[0032] The processing device 10 is configured by a computer or the like that includes a processing unit 10a, a storage unit 10b, and an output unit 10c. The processing unit 10a is, for example, any of a variety of processors suitable for computer control, such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or a quantum processor.

[0033] The storage unit 10b is, for example, a flash memory, a hard disk, a ROM (Read Only Memory), or the like. The storage unit 10b stores computer programs and necessary information to be executed by the processing unit 10a. The processing unit 10a executes computer programs stored in a computer-readable non-transitory recording medium such as the storage unit 10b to realize various processing functions of the processing device 10. The processing unit 10a also has a function of detecting the amount of reflection of a reflected signal when an input signal is applied to the detection cable 2, and of calculating the amount of deformation of the detection cable 2. Furthermore, the processing unit 10a also has a function of performing processing to determine the external force acting on the outer surface 6a of the sheet-like member 6 (or the detection cable 2) based on the deformation amount of the detection cable 2.

[0034] The output unit 10c has a function of outputting various information related to the processing by the processing unit 10a to the outside. The output unit 10c may include a wireless communication device. In this case, the output unit 10c outputs various information by wireless communication. The output unit 10c may also include a monitor, an indicator, and a speaker. In this case, the output unit 10c outputs various information by these devices.

[0035] [Deformation of the detection cable 2 and the sheet-like member 6] FIG. 4A is a cross-sectional view showing an example of a sheet-like member 6 in a state where no external force is applied. As shown in Fig. 4A, when no external force is acting on the sheet-like member 6, the outer diameter of the detection cable 2 is approximately circular. Therefore, the interval W1 and the interval W2 are approximately the same value. In Fig. 4A, the interval W1 is the interval between the conductor wire 12 and the shield layer 16 in the thickness direction of the sheet-like member 6. In Fig. 4A, the interval W2 is the interval between the conductor wire 12 and the shield layer 16 in the planar direction of the sheet-like member 6 (the direction along the outer surface 6a).

[0036] FIG. 4B is a cross-sectional view showing an example of the sheet-like member 6 in a state where an external force is applied. FIG. 4B shows a state in which an external force is applied to a portion P (see FIG. 1) that is a part of the outer surface 6a, and a part of the sheet-like member 6 is compressed and deformed in the thickness direction. As shown in FIG. 4B, when sheet-shaped member 6 is compressed and deformed in the thickness direction, detection cable 2 is compressed in the radial direction in accordance with the deformation, and part of detection cable 2 in the longitudinal direction is deformed.

[0037] The insulating layer 14 of the detection cable 2 has six holes 20. Therefore, when deformation occurs in a portion of the detection cable 2 in the longitudinal direction, the holes 20 located in the portion P are crushed. When the voids 20 are collapsed, the insulating layer 14 is significantly deformed. 4B, when the sheet-like member 6 is compressed and deformed in the thickness direction, the outer shape of the detection cable 2 is deformed into an ellipse. At this time, the minor axis of the detection cable 2 is along the thickness direction. The major axis of the detection cable 2 is along the planar direction. Therefore, the distance W3 is smaller than the distance W4. The distance W3 is the distance between the conductor wires 12 and the shielding layer 16 in the thickness direction of the sheet-shaped member 6 in Fig. 4B. The distance W4 is the distance between the conductor wires 12 and the shielding layer 16 in the planar direction of the sheet-shaped member 6 in Fig. 4B. Furthermore, the interval W3 is smaller than the interval W1 (W2), and the interval W4 is larger than the interval W1.

[0038] In this manner, the distance between the conductor wire 12 and the shield layer 16 at the deformed portion of the detection cable 2 changes significantly. Therefore, the impedance of the deformed portion of the detection cable 2 changes significantly with respect to the impedance before the deformation. When the impedance at the deformed portion of the detection cable 2 changes significantly, the amount of reflection of the reflected signal when a predetermined input signal is applied to the detection cable 2 also changes significantly.

[0039] Here, the detection device 4 (FIG. 1) has a function of detecting the reflection amount of a reflected signal when an input signal is applied to the detection cable 2, as described above. Therefore, by detecting the amount of reflection of the reflected signal when an input signal is applied to the detection cable 2, the deformation of the detection cable 2 and the deformation of the sheet-like member 6 to which the detection cable 2 is attached can be properly detected.

[0040] That is, according to the above configuration, since the insulating layer 14 has a plurality of holes 20, when the detection cable 2 is deformed, the insulating layer 14 can be deformed more greatly than when it does not have the holes 20. This makes it possible to greatly change the impedance of the deformed portion of the detection cable 2, and to greatly change the reflection amount of the reflected signal when an input signal is applied to the detection cable 2 during deformation. As described above, the detection cable 2 of the present embodiment can be used as a sensor capable of detecting deformation of itself and deformation of the sheet-like member 6 (detection target) with high sensitivity and appropriateness.

[0041] The outer diameter of the detection cable 2 is set in the range of 0.3 mm or more and 1.0 mm or less. If the outer diameter is smaller than 0.3 mm, the amount of deformation of the insulating layer 14 caused by the crushing of the holes 20 due to deformation is small, and there is a risk that it will be difficult to adequately detect the deformation of the detection cable 2. If the outer diameter is larger than 1.0 mm, there is a risk that it will be difficult to attach the detection cable 2 to the sheet-like member 6, which is the object to be detected for deformation. By setting the outer diameter to be 0.3 mm or more and 1.0 mm or less, the detection cable 2 can be suitably used as a sensor that can appropriately detect deformation of the detection cable 2 itself and deformation of the sheet-like member 6.

[0042] In this embodiment, the ratio of the cross-sectional area of ​​the plurality of pores 20 to the cross-sectional area of ​​the insulating layer 14 (porosity) is set in the range of 30% or more and 80% or less. If the proportion of the cross-sectional area of ​​the multiple holes 20 is less than 30%, the degree of crushing of the holes 20 at the deformed portion may not be sufficient when deformation occurs in the detection cable 2. Furthermore, if the proportion of the cross-sectional area of ​​the multiple holes 20 is greater than 80%, the strength required for the detection cable 2 may be insufficient. By setting the proportion of the cross-sectional area of ​​the plurality of holes 20 to 30% or more and 80% or less, it is possible to obtain holes 20 that are appropriately crushed by deformation of the detection cable 2.

[0043] The porosity is more preferably 40% or more and 60% or less, and even more preferably 50% or more and 60% or less. The porosity can be adjusted by changing the diameter of the holes 20, and can also be adjusted by changing the number of the holes 20. Furthermore, the porosity can also be adjusted by changing the cross-sectional shape of the holes 20 to a shape other than a circle.

[0044] Furthermore, the Young's modulus of the insulating layer 14 may be not less than 5 MPa and not more than 260 MPa. If the Young's modulus of the insulating layer 14 is smaller than 5 MPa, the strength required for the detection cable 2 may be insufficient. If the Young's modulus of the insulating layer 14 is larger than 260 MPa, when the detection cable 2 is deformed, the plurality of holes 20 in the deformed portion may not be crushed to a sufficient degree. By setting the Young's modulus of the insulating layer 14 to be equal to or greater than 5 MPa and equal to or less than 260 MPa, it is possible to obtain the pores 20 that are appropriately crushed by the deformation of the detection cable 2. The Young's modulus of the insulating layer 14 is more preferably 5 MPa to 20 MPa, and even more preferably 10 MPa to 20 MPa.

[0045] [Regarding processing by the processing device 10] As described above, the processing unit 10a of the processing device 10 (Figure 3) performs a process of detecting the amount of reflection of the reflected signal when an input signal is applied to the detection cable 2, a process of calculating the amount of deformation of the detection cable 2 based on the amount of reflection of the reflected signal when an input signal is applied to the detection cable 2, and a process of calculating the external force acting on the outer surface 6a of the sheet-like member 6 based on the amount of deformation. The processing unit 10a of this embodiment obtains an estimated value of the compression ratio as the amount of deformation of the detection cable 2. The compression ratio is the ratio of the amount of crushing to the diameter of the detection cable 2 before deformation. The amount of crushing is the difference between the diameter of the detection cable 2 before deformation and the minor axis of the detection cable 2 after deformation.

[0046] The storage unit 10b stores data indicating the relationship between the amount of reflection of the reflected signal relative to the input signal and the compression rate of the detection cable 2. Furthermore, the storage unit 10b stores data indicating the relationship between the amount of deformation of the detection cable 2 and the external force acting on the outer surface 6a. FIG. 5A is a diagram showing an example of data showing the relationship between the amount of reflection and the compression ratio of the detection cable 2, and FIG. 5B is a diagram showing an example of data showing the relationship between the compression ratio of the detection cable 2 and the external force acting on the outer surface 6a. As shown in FIG. 5A, there is a certain relationship between the reflection amount and the compression ratio. The processing unit 10a refers to this data and obtains an estimate of the compression rate of the detection cable 2 based on the amount of reflection.

[0047] Furthermore, as shown in FIG. 5B, there is a certain relationship between the compressibility of the detection cable 2 and the external force acting on the outer surface 6a. The processing unit 10a refers to this data and determines the external force based on the estimated value of the compression ratio. Each of the above data can be obtained by experiments, simulations, etc. Each of the above data may be in the form of graphs such as those shown in Figures 5A and 5B, or may be in the form of a table or a mathematical formula. Furthermore, if the memory unit 10b stores data indicating the relationship between the amount of reflection and the external force acting on the outer surface 6a, the processing unit 10a may use this data to determine the external force based on the amount of reflection.

[0048] The processing unit 10a executes a process of continuously applying an input signal to the detection cable 2 and detecting the amount of reflection. Furthermore, the processing unit 10a executes a process of calculating an estimated value of the compression ratio (hereinafter also simply referred to as the compression ratio) of the detection cable 2 based on the amount of reflection, and a process of calculating an external force acting on the outer surface 6a of the sheet-like member 6 based on the compression ratio.

[0049] When the compression ratio and the external force are calculated, the processing unit 10a outputs at least the external force to the outside via the output unit 10c. As described above, according to the detection system 1 of this embodiment, it is possible to appropriately detect the deformation of the detection cable 2 (sheet-like member 6) based on the reflection amount of the reflected signal, and obtain the compression ratio (amount of deformation).

[0050] [Regarding the detection system according to the second embodiment] FIG. 6 is a diagram illustrating an example of an overall configuration of a detection system according to the second embodiment. The detection cable 2 of the detection system 1 of this embodiment differs from that of the first embodiment in that it is attached to a power cable 30 which is another cable. The detection cable 2 of this embodiment is used as a sensor that detects bending deformation of the power cable 30 by being attached to the power cable 30 which is the object to be detected.

[0051] FIG. 7 is a cross-sectional view of the power cable 30 taken along a plane perpendicular to the longitudinal direction thereof. The power cable 30 includes two power lines 32, one twisted pair signal line 34, and one electrical wire 36. The two power lines 32 are insulated wires for supplying power. Of the two power lines 32, one is a positive electric wire and the other is a negative electric wire. Each of the two power lines 32 has a core wire 32a and a coating 32b. The core wire 32a is made of a conductor such as copper or aluminum. The core wire 32a may be a stranded wire made of a plurality of strands twisted together, a twisted wire made of strands twisted together, or a single strand. The coating 32b is formed around the core wire 32a. The coating 32b is made of resin.

[0052] The twisted pair signal line 34 is a covered electric wire for transmitting signals. The twisted pair signal wire 34 includes two signal wires 35. The two signal wires 35 are twisted together to form one twisted pair signal wire 34. Each of the two signal wires 35 has a core wire 35a and a coating 35b. The core wire 35a is an electric wire made of a conductor such as copper or aluminum. The core wire 35a may be a twisted wire made of a plurality of strands twisted together, a twisted wire made of twisted wires twisted together, or a single strand. The coating 35b is formed around the core wire 35a. The coating 35b is made of resin. The electric wire 36 is a generally used coated electric wire. The electric wire 36 also has a core wire 36a made of a conductor and a coating 36b made of resin.

[0053] The power cable 30 further has an outer covering layer 38. The outer covering layer 38 is a resin layer that covers the outer periphery of each electric wire. The outer covering layer 38 may be composed of a plurality of layers or a single layer. The individual electric wires are bundled into a single power cable 30 by an outer covering layer 38 .

[0054] The detection cable 2 is disposed approximately at the center of the cross section of the power cable 30 . The configuration of the detection cable 2 is similar to that of the first embodiment. 6 and 7, the detection cable 2 is inserted inside the power cable 30. Therefore, when the power cable 30 is bent and deformed, the detection cable 2 is also bent and deformed in response to the power cable 30 being bent and deformed.

[0055] FIG. 8A is a diagram showing the power cable 30 in a bent and deformed state from an elongated state. 8A, the detection cable 2 is bent and deformed in response to the bending deformation of the power cable 30. Therefore, the radius of curvature of the detection cable 2 is approximately the same as the radius of curvature of the power cable 30.

[0056] FIG. 8B is an example of a cross-sectional view of detection cable 2 at bent portion B in FIG. 8A. 8B, the outer shape of the detection cable 2 at the bent portion B is deformed into an elliptical shape. At this time, the minor axis of the detection cable 2 is aligned along a radial direction that determines the radius of curvature. The major axis of the detection cable 2 is aligned along a direction perpendicular to the radial direction that determines the radius of curvature.

[0057] Here, it is known that the aspect ratio of the shield layer 16 of the detection cable 2 has a correlation with the radius of curvature of the detection cable 2 . In addition, it is known that the aspect ratio of the shield layer 16 has a correlation with the amount of change in the characteristic impedance of the detection cable 2. The aspect ratio of the shield layer 16 is the ratio of the major axis LR to the minor axis SR of the shield layer 16.

[0058] Furthermore, the amount of reflection of the reflected signal when an input signal is applied to the detection cable 2 changes according to the change in the characteristic impedance of the detection cable 2. Therefore, the radius of curvature of the detection cable 2 can be obtained from the amount of reflection of the reflected signal when an input signal is applied to the detection cable 2.

[0059] Therefore, the detection device 4 of the present embodiment obtains an estimated value of the radius of curvature of the detection cable 2 as the deformation amount of the detection cable 2. The storage unit 10b stores data indicating the relationship between the reflection amount of the reflected signal and the radius of curvature of the detection cable 2. The processing unit 10a refers to this data and obtains an estimate of the radius of curvature of the detection cable 2 based on the amount of reflection. The above data can be obtained by experiments, simulations, etc. The above data may be in the form of a graph, a table, or a mathematical formula.

[0060] The processing unit 10a executes a process of continuously applying an input signal to the detection cable 2 and detecting the amount of reflection. Furthermore, the processing unit 10a executes a process of calculating the radius of curvature (amount of deformation) of the detection cable 2 based on the amount of reflection. As described above, the radius of curvature of the detection cable 2 is approximately the same as the radius of curvature of the power cable 30. Therefore, the detection system 1 can obtain the radius of curvature of the power cable 30 by obtaining the radius of curvature of the detection cable 2 based on the amount of reflection.

[0061] After determining the radius of curvature, the processing unit 10a outputs the radius of curvature to the outside via the output unit 10c. As described above, in the detection system 1 according to this embodiment as well, it is possible to appropriately detect the deformation of the detection cable 2 and obtain the radius of curvature (amount of deformation) based on the amount of reflection of the input signal.

[0062] [Modifications] In each of the above embodiments, the multiple holes 20 in the insulating layer 14 of the detection cable 2 have a cylindrical shape extending along the longitudinal direction of the conductor wire 12. However, the multiple holes 20 are not limited to this. For example, the number of holes 20 is not limited to six as in each of the above embodiments, and the number of holes 20 may be more, such as seven or eight, or less, such as five or four. 9, the cross-sectional shape of the hole 20 may be an ellipse having a curvature along the circumferential direction of the detection cable 2. Furthermore, the insulating layer 14 may be formed from a foam material, and the plurality of bubbles contained in the foam material may function as the plurality of voids 20.

[0063] In addition, in each of the above embodiments, the detection cable 2 is attached to a detection target such as the sheet-like member 6 or the power cable 30, but the detection cable 2 can be used alone as a pressure sensor. In this case, the detection cable 2 is used as a sensor that detects, for example, an external force acting on the outer surface of the detection cable 2.

[0064] [About verification testing] Next, a verification test carried out on the characteristics of the detection cable 2 will be described. As a test method, a model of the detection cable 2 of each of the above-described embodiments was constructed by a computer as an experimental example, and the characteristics of the detection cable 2 were obtained by computer simulation using the experimental example. In addition, for some of the experimental examples, the characteristics were measured using an actual detection cable 2, and the actual measurement results were compared with the results of the computer simulation. For the model of the detection cable 2, experimental examples 1 to 4 shown below were set.

[0065] (Experimental Example 1) In Experimental Example 1, it is assumed that the insulating layer 14 is formed from a resin composition containing PTFE as a main component. Outer diameter of detection cable 2: 0.32 mm Length of detection cable 2: 1.5m Rated value of characteristic impedance of detection cable 2: 85 Ω Porosity: 43.3% Young's modulus of insulating layer 14: 0.5 GPa Young's modulus of conductor wire 12: 100 GPa Young's modulus of shield layer 16: 100 GPa Young's modulus of coating layer 18: 4.0 GPa

[0066] (Experimental Example 2) In Experimental Example 2, the porosity was set to 53.1%. Other than that, the experiment was the same as Experimental Example 1.

[0067] (Experimental Example 3) In Experimental Example 3, the insulating layer 14 was assumed to be formed from a resin composition containing low-density polyethylene as a main component, and the Young's modulus of the insulating layer 14 was set to 0.25 GPa (250 MPa). The rest of the experiment was the same as in Experimental Example 1.

[0068] (Experimental Example 4) In Experimental Example 4, the insulating layer 14 was assumed to be made of an insulating rubber composition, and the Young's modulus of the insulating layer 14 was set to 0.001 GPa (10 MPa). In addition, the insulating layer 14 was given the property of being elastically deformable in order to represent a rubber composition. The rest of the experiment was the same as in Experimental Example 1.

[0069] (Compression rate during compression deformation) A computer simulation was used to determine the cross-sectional state of the deformed portion of the detection cable 2 when the longitudinal center portion of the detection cable 2 in the above-mentioned Experimental Example 1 was subjected to radial compression deformation within a range of 40 mm in the longitudinal direction. The deformed portion of the detection cable 2 reproduced the deformation state that would occur when the above-mentioned range was compressed so as to be sandwiched from both sides in the radial direction.

[0070] FIG. 10 is a diagram showing the results of computer simulation of the cross-sectional state of the deformed portion when an experimental example of the detection cable 2 is subjected to compressive deformation. Here, the cross-sectional state of the deformed portion was obtained for each of the cases where the compression ratio was 0%, 37%, 1%, 52.3%, and 62.5%. Note that the compression ratio of 0% is the cross-sectional state before deformation (undeformed). As described above, the compression ratio is the ratio of the amount of crushing to the diameter R1 of the detection cable 2 before deformation. The amount of crushing is the difference between the diameter R1 of the detection cable 2 before deformation and the minor diameter R2 of the detection cable 2 after deformation.

[0071] As shown in FIG. 10, it can be seen that the voids 20 in the deformed portions are crushed, and large deformation occurs in the insulating layer 14 in the deformed portions. Furthermore, when the compression ratio is 37.1% and 52.3%, some of the six pores 20 are not completely crushed. When the compression ratio is 62.5%, all of the six pores 20 are completely crushed. Thus, it can be seen that when the compression ratio exceeds approximately 60%, all of the pores 20 are crushed.

[0072] It can also be seen that the outer shape of the detection cable 2 is deformed into an oval shape due to being compressed in the radial direction. Furthermore, the distance between the conductor wire 12 and the shield layer 16 in the short diameter direction becomes smaller as the compression ratio increases, and the distance between the conductor wire 12 and the shield layer 16 in the long diameter direction perpendicular to the short diameter direction becomes larger as the compression ratio increases.

[0073] FIG. 11 is a graph showing the relationship between the compression ratio and the impedance at the deformed portion of the detection cable 2. As shown in FIG. In Fig. 11, the horizontal axis indicates the compression ratio, and the vertical axis indicates the impedance of the deformed portion. The impedance of the deformed portion was obtained by computer simulation using the above-mentioned experimental example (model) of the detection cable 2. The impedance of the deformed portion is the impedance obtained when an input signal with a frequency of 10 MHz is applied.

[0074] As shown in FIG. 11, it can be seen that the impedance of the deformed portion of the detection cable 2 changes significantly with respect to the impedance before the deformation. Moreover, the impedance of the deformed portion decreases as the compression ratio increases, and it is apparent that there is a correlation between the impedance of the deformed portion and the compression ratio. If the impedance at the deformed portion changes significantly, the reflection amount of the reflected signal when a predetermined input signal is applied to the detection cable 2 also changes significantly. In other words, there is a correlation between the impedance at the deformed portion and the reflection amount. Therefore, there is also a correlation between the reflection amount and the compression ratio. Therefore, it is understood that the detector 4 is capable of determining the compression ratio based on the reflection amount of the reflected signal relative to the input signal.

[0075] FIG. 12A is a graph showing the relationship between the frequency of an input signal and the amount of reflection of a reflected signal when the input signal is applied to detection cable 2. As shown in FIG. In Fig. 12A, the horizontal axis indicates the frequency of the input signal, and the vertical axis indicates the amount of reflection. Note that the amount of reflection shown here is the normalized value of the amplitude (mag) of the reflection coefficient (S parameter S11) when an input signal is applied to the detection cable 2. The amount of reflection was obtained by computer simulation using the experimental example (model) of the detection cable 2 described above.

[0076] As shown in FIG. 12A, in the range below 80 MHz, if the frequency of the input signal is set to a predetermined value, the amount of reflection decreases as the compression ratio increases, and it can be seen that there is a correlation between the amount of reflection and the compression ratio. Also, in the range of 80 MHz or less, it can be seen that as the frequency of the input signal is increased, the change in compression ratio relative to the change in the amount of reflection increases. Therefore, the frequency of the input signal is set so as to obtain an appropriate amount of reflection.

[0077] FIG. 12B is a graph showing the relationship between the frequency of an input signal and the amount of reflection of a reflected signal when the input signal is applied to detection cable 2 when detection cable 2 is actually deformed. FIG. 12B shows the results of actually creating a detection cable 2 equivalent to Experimental Example 1, and actually compressing and deforming the created detection cable 2 to measure the amount of reflection. Comparing FIG. 12A with FIG. 12B, they show almost the same characteristics. From this result, it can be determined that the characteristics obtained by the computer simulation model represent the characteristics of the actual detection cable 2.

[0078] As described above, the results of the tests conducted on the radial compressive deformation of the detection cable 2 show that when the detection cable 2 is deformed, the holes 20 are crushed, thereby causing a large deformation of the insulating layer 14, and that this can significantly change the amount of reflection of the reflected signal when an input signal is applied to the detection cable during deformation. From this result, it can be confirmed that the detection cable 2 of this embodiment can be used as a sensor that can appropriately detect its own deformation.

[0079] (Relationship between compression ratio and crushing load) The cross-sectional state of the deformed portion of the detection cable 2 when the longitudinal central portion of the detection cable 2 of the above-mentioned Experimental Examples 1 to 4 was subjected to radial compression deformation within a range of 40 mm in the longitudinal direction was obtained by computer simulation. The deformed portion of the detection cable 2 reproduced the deformation state that occurs when the above-mentioned range is compressed so as to be sandwiched from both sides in the radial direction.

[0080] FIG. 13 is a diagram showing the results of computer simulation of the cross-sectional state of the deformed portion when the detection cables 2 of Experimental Examples 1 to 4 are compressively deformed. Here, the cross-sectional state of the deformed portion was obtained for each of the cases where the compression ratio was 31.3%, 62.5%, and after unloading. In addition, for the cases where the compression ratio was 31.3% and 62.5%, the load (crushing load) acting on the detection cable 2 during deformation was also obtained by computer simulation.

[0081] As shown in FIG. 13, when the compression ratio is 31.3%, some of the six holes 20 are not completely crushed in all experimental examples. When the compression ratio was 62.5%, all of the six pores 20 were completely crushed in all experimental examples. As in Fig. 10, this result also shows that when the compression ratio exceeds approximately 60%, all of the pores 20 are crushed.

[0082] The crushing loads at a compression rate of 62.5% in Experimental Examples 2 and 3 are lower than the crushing load at a compression rate of 62.5% in Experimental Example 1 by approximately 30 to 40 N / mm. Moreover, the crushing load at a compression rate of 62.5% in Experimental Example 4 is about 1 / 10 of the crushing load at a compression rate of 62.5% in Experimental Example 1.

[0083] Furthermore, when the cross-sectional state after unloading is examined, the cross-sectional state after unloading in Experimental Examples 1 to 3 does not recover significantly from the crushed state, but maintains the crushed state. On the other hand, the cross-sectional state of Experimental Example 4 after the load was removed was restored from the crushed state to the original state. This is because the insulating layer 14 in Experimental Examples 1 to 3 is assumed to be formed from a resin composition mainly composed of PTFE and a resin composition mainly composed of low-density polyethylene, whereas the insulating layer 14 in Experimental Example 4 is assumed to be formed from a rubber composition. In Experimental Example 4, the insulating layer 14 is elastically deformable, and therefore returns to its original shape when the load is removed.

[0084] FIG. 14A is a graph showing the relationship between compressibility and crushing load. 14A, the horizontal axis represents the compression ratio, and the vertical axis represents the crushing load. The crushing load was obtained by computer simulation using the experimental example (model) of the detection cable 2 described above. As shown in FIG. 14A, in Experimental Examples 1 to 3, the crushing load at which the compression ratio becomes 60%, where all of the pores 20 are completely crushed, is 40 N / mm or more. On the other hand, in Experimental Example 4, the crushing load at which the compression ratio becomes 60% is an extremely low value compared to the other experimental examples.

[0085] FIG. 14B is a graph in which a portion of the vertical axis of the graph in FIG. 14A is enlarged. As shown in FIG. 14B, in Experimental Example 4, it is found that the crushing load at which the compression rate becomes 60% is about 5 N / mm. From these results, when assuming that the detection cable 2 is used at a compression ratio ranging from 0% to 60%, at which all of the pores 20 are completely crushed, it can be determined that experimental example 4 (insulating layer 14 formed from a rubber composition), which can cover the range of compression ratios with a relatively low crushing load, can enable more sensitive and appropriate detection than the other experimental examples.

[0086] (About bending deformation) The aspect ratios of the shield layer 16 in the deformed portion of the detection cable 2 when the detection cable 2 of each of the above experimental examples 1 to 4 was bent at a plurality of different radii of curvature were obtained by computer simulation. As described above, the aspect ratio is the ratio of the major axis LR to the minor axis SR of the shield layer 16 (FIG. 8B).

[0087] FIG. 15A is a graph showing the relationship between the radius of curvature and the aspect ratio of the detection cable 2. As shown in FIG. 15A, in all of the experimental examples, it is found that the aspect ratio has a correlation with the radius of curvature of detection cable 2 if the range of the radius of curvature is limited.

[0088] In addition, the aspect ratio of the shield layer 16 was converted into the amount of change ΔZ by computer simulation, and the relationship between the radius of curvature and the amount of change ΔZ was obtained. The amount of change ΔZ is the difference between the characteristic impedance of the detection cable 2 before deformation and the characteristic impedance of the detection cable 2 after deformation.

[0089] FIG. 15B is a graph showing the relationship between the radius of curvature of the detection cable 2 and the amount of change ΔZ. As shown in FIG. 15B, in all of the experimental examples, it is found that the amount of change ΔZ has a correlation with the radius of curvature of the detection cable 2 if the range of the radius of curvature is limited.

[0090] As described above, the amount of reflection of the reflected signal when an input signal is applied to the detection cable 2 changes according to the change in the characteristic impedance of the detection cable 2. From these results, it is evident that the radius of curvature of the detection cable 2 when it is bent and deformed can be obtained from the amount of reflection of the reflected signal when an input signal is applied to the detection cable 2.

[0091] 〔others〕 It should be noted that the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, not by the meaning described above, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0092] 1. Detection System 2 Detection cable 2a 1st end 2b Second end 3 Terminator 4. Detection Device 5 railroad tracks 6 Sheet-like members 6a Exterior 6b Hole 7 railroad tracks 8 Directional coupler 9 Signal source 10 Processing equipment 10a Processing section 10b Storage section 10c output section 12 Conductor Wire 14 Insulating layer 16 Shielding Layer 18 Covering layer 20 Vacancies 22 Base 24 Liquid-permeable outer conductor 30 Power Cable 32 Power Lines 32a core wire 32b Covering 34 Twisted pair signal wire 35 Signal Line 35a core wire 35b Covering 36 Electric wire 36a core wire 36b coating 38 outer coating layer

Claims

1. A conductor wire; an insulating layer provided on an outer periphery of the conductor wire; a shield layer provided on an outer circumferential side of the insulating layer, The insulating layer has a plurality of holes provided around the conductor line. Detection cable.

2. The plurality of holes have a cylindrical shape extending along the longitudinal direction of the conductor wire. The sensing cable according to claim 1 .

3. The ratio of the cross-sectional area of ​​the plurality of holes to the cross-sectional area of ​​the insulating layer is 30% or more and 80% or less. The sensing cable according to claim 2 .

4. The Young's modulus of the insulating layer is 5 MPa or more and 260 MPa or less. The sensing cable according to claim 2 .

5. The insulating layer is made of a rubber material having insulating properties. The sensing cable according to claim 2 .

6. The insulating layer is made of a resin material containing low-density polyethylene. The sensing cable according to claim 2 .

7. The outer diameter is 0.3 mm or more and 1.0 mm or less. The detection cable according to any one of claims 1 to 6.

8. A detection cable; a detection device that detects a reflection amount of a reflected signal when an input signal is applied to the detection cable, The detection cable is A conductor wire; an insulating layer provided on an outer periphery of the conductor wire; a shield layer provided on an outer circumferential side of the insulating layer, The insulating layer has a plurality of holes provided around the conductor line. Detection system.

9. The detection device includes: a signal source for applying the input signal to the conductor line; a processing device that executes a process of detecting the amount of reflection and a process of calculating an amount of deformation of the detection cable based on the amount of reflection. The detection system of claim 8.

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