Tactile sensor and method for manufacturing tactile sensor

Abstract

To provide a tactile sensor equipped with an electroconductive porous body and advantageous in terms of sensitivity and spatial resolution.SOLUTION: A tactile sensor 1a comprises a plurality of electrodes 10, an electroconductive porous body 20, a conductor 30, and a measurement unit 50. The electroconductive porous body 20 is in contact with the plurality of electrodes 10. The electroconductive porous body 20 has different electroconductivity in a specific direction. The conductor 30 is separated from the electroconductive porous body 20 in the specific direction. The measurement unit 50 measures the state of contact of an object with at least one of the electroconductive porous body 20 and the conductor 30 on the basis of the electric potential of the plurality of electrodes 10. The electroconductive porous body 20 has a first end section 21 and a second end section 22. The first end section 21 is formed at one end on the side of the conductor 30 in the specific direction. The electroconductivity at the first end section 21 of the electroconductive porous body 20 is greater than the electroconductivity at the second end section 22 of the electroconductive porous body 20.SELECTED DRAWING: Figure 2A

Description

[Technical field]

[0001] The present invention relates to a tactile sensor and a method for manufacturing a tactile sensor. [Background technology]

[0002] Tactile sensors are known in the art.

[0003] For example, Patent Document 1 describes a tactile sensor including a detection unit and a measurement unit. The detection unit has a first conductor and a second conductor. The first conductor is provided with a plurality of electrodes. The second conductor faces the first conductor. The measurement unit measures contact of a contacting object based on the potential of the electrodes.

[0004] Patent Document 2 describes a conductive porous resin molded body as a stress-strain sensor material. This conductive porous resin molded body has pores and conductive particles dispersed in the resin, and the diameters of the pores are distributed in a gradient. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-168247 A [Patent Document 2] JP 2018-39862 A Summary of the Invention [Problem to be solved by the invention]

[0006] It is conceivable to use a conductive porous body in a tactile sensor to measure the contact state of an object. The use of a conductive porous body is considered to be advantageous in terms of making the tactile sensor flexible and lightweight. On the other hand, according to the study by the present inventors, it has been newly found that the use of a thick conductive porous body in a tactile sensor tends to result in a problem that the sensitivity and spatial resolution of the tactile sensor to the contact of an object are likely to be reduced. Such a problem is neither described nor suggested in Patent Documents 1 and 2.

[0007] Therefore, the present invention provides a tactile sensor that includes a conductive porous body and is advantageous in terms of sensitivity and spatial resolution. [Means for solving the problem]

[0008] The present invention relates to A plurality of electrodes; A conductive porous body in contact with the plurality of electrodes and having different electrical conductivities in a specific direction; a conductor disposed apart from the conductive porous body in the specific direction; a measuring unit that measures a contact state of an object with at least one of the conductive porous body and the conductor based on the potentials of the plurality of electrodes; the conductive porous body has a first end portion formed at one end on the conductor side in the specific direction and a second end portion formed at the other end in the specific direction, The electrical conductivity at the first end of the conductive porous body is higher than the electrical conductivity at the second end of the conductive porous body. A tactile sensor is provided.

[0009] The present invention also provides a method for producing a method for manufacturing a semiconductor device comprising the steps of: A method for manufacturing a tactile sensor, comprising the steps of: The tactile sensor includes: A plurality of electrodes; A conductive porous body in contact with the plurality of electrodes and having different electrical conductivities in a specific direction; a conductor disposed apart from the conductive porous body in the specific direction; a measuring unit that measures a contact state of an object with at least one of the conductive porous body and the conductor based on the potentials of the plurality of electrodes; The method includes arranging the conductive porous body such that a first end portion, which is formed at one end of the conductive porous body on the side of the conductor in the specific direction and has a higher electrical conductivity than a second end portion of the conductive porous body formed at the other end in the specific direction, is located between the conductor and the second end portion. A method of manufacture is provided. Effect of the Invention

[0010] The above-described tactile sensor is advantageous in terms of sensitivity and spatial resolution while including a conductive porous body. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view showing an example of a tactile sensor according to the present invention. [Figure 2A] FIG. 2A is a cross-sectional view of the tactile sensor taken along line II-II in FIG. [Figure 2B] FIG. 2B is a cross-sectional view of a tactile sensor that has been deformed by contact with an object. [Diagram 3] FIG. 3 is a graph showing an example of the electrical conductivity of a conductive porous body. [Figure 4] FIG. 4 is a cross-sectional view that illustrates an example of a conductive porous body. [Diagram 5] FIG. 5 is a cross-sectional view that illustrates a schematic diagram of another example of a conductive porous body. [Figure 6] FIG. 6 is a cross-sectional view showing a modified example of the tactile sensor. [Figure 7] FIG. 7 is a plan view showing an example of the arrangement of a plurality of electrodes in a tactile sensor. [Figure 8] FIG. 8 is a plan view showing another example of the arrangement of a plurality of electrodes in a tactile sensor. [Figure 9] FIG. 9 is a diagram illustrating an example of a circuit of a measurement unit of a tactile sensor. [Figure 10]FIG. 10 is a plan view showing yet another example of the arrangement of a plurality of electrodes in a tactile sensor. [Figure 11] FIG. 11 is a perspective view showing another example of a tactile sensor according to the present invention. [Figure 12A] FIG. 12A is a side view that illustrates a schematic diagram of a calculation model used in calculations in the examples. [Figure 12B] FIG. 12B is a perspective view that illustrates a calculation model used in calculations in the examples. [Figure 12C] FIG. 12C is a perspective view that illustrates a calculation model used in calculations in the examples. [Figure 13A] FIG. 13A is a graph showing a schematic diagram of evaluation indexes of sensitivity and linearity of calculation results in an example. [Figure 13B] FIG. 13B is a graph showing a schematic representation of the spatial resolution of the calculation results in the example. [Figure 14A] FIG. 14A is a graph showing the results of sensitivity evaluation based on calculations in an example. [Figure 14B] FIG. 14B is a graph showing the results of linearity evaluation based on calculations in the examples. [Figure 14C] FIG. 14A is a graph showing the evaluation results of spatial resolution based on calculations in an example. [Figure 15A] FIG. 15A is a graph showing the relationship between the load and the output voltage corresponding to the center of the load in the evaluation sensor of Sample 1. FIG. [Figure 15B] FIG. 15B is a graph showing the relationship between the normalized output on the center line passing through the center of the load in the evaluation sensor related to Sample 1 and the position on that center line. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following description is for illustrative purposes only and the present invention is not limited to the following embodiment.

[0013] As shown in FIG. 1 and FIG. 2A, the tactile sensor 1a includes a plurality of electrodes 10, a conductive porous body 20, a conductor 30, and a measuring unit 50. The conductive porous body 20 is in contact with the plurality of electrodes 10. The conductive porous body 20 has different electrical conductivities in a specific direction. The conductor 30 is disposed apart from the conductive porous body 20 in a specific direction. The measuring unit 50 measures the contact state of an object with at least one of the conductive porous body 20 and the conductor 30 based on the potential of the plurality of electrodes 10. For example, when an object contacts at least one of the conductive porous body 20 and the conductor 30, as shown in FIG. 2B, the conductive porous body 20 and the conductor 30 come into contact with each other due to deformation of at least one of the conductive porous body 20 and the conductor 30, and the magnitude of the contact resistance between the conductive porous body 20 and the conductor 30 may vary. The potential of the plurality of electrodes 10 may change due to the variation in the magnitude of the contact resistance. Therefore, the contact state of the object with at least one of the conductive porous body 20 and the conductor 30 can be measured based on the potentials of the multiple electrodes 10. The conductor 30 is electrically connected to a power source (not shown) such as a DC power source. The measurement unit 50 may be equipped with this power source. Details of the method for measuring the contact state of the object with at least one of the conductive porous body 20 and the conductor 30 based on the potentials of the multiple electrodes 10 can be understood by referring to JP 2019-168247 A. The measurement of the contact state of the object includes, for example, measurement of the contact position of the object with at least one of the conductive porous body 20 and the conductor 30. The measurement of the contact state of the object may include, for example, measurement of the contact force of the object with at least one of the conductive porous body 20 and the conductor 30.

[0014] As described above, the tactile sensor 1a is provided with the conductive porous body 20, and therefore is likely to have flexibility. In addition, the tactile sensor 1a is advantageous in terms of light weight. On the other hand, according to the study by the present inventors, it was newly discovered that when a conductive porous body is used in a tactile sensor, the sensitivity and spatial resolution of the tactile sensor to contact with an object are likely to be reduced. This is because the potential contrast at the multiple electrodes is likely to decrease due to the thickness of the conductive porous body. Therefore, as a result of extensive study, the present inventors have newly developed a tactile sensor that is advantageous in terms of sensitivity and spatial resolution while using a conductive porous body.

[0015] As shown in FIG. 2A, the conductive porous body 20 has a first end 21 and a second end 22. The first end 21 is formed at one end of the conductive porous body 20 on the conductor 30 side in a specific direction. The second end 22 is formed at the other end of the conductive porous body 20 in the specific direction. The conductivity σ of the conductive porous body 20 at the first end 21 is 21 is the electrical conductivity σ at the second end 22 of the conductive porous body 20 22 With such a configuration, coupled with the fact that the conductive porous body 20 has different electrical conductivities in specific directions, the tactile sensor 1a is more likely to have the desired sensitivity and spatial resolution.

[0016] The conductivity of the conductive porous body 20 is not limited to a specific value. The conductive porous body 20 has a conductivity that varies in a specific direction, for example, within a range of 0.001 to 100 S / m. With this configuration, the tactile sensor 1a is more likely to have the desired sensitivity and spatial resolution.

[0017] Conductivity σ 21 is the conductivity σ 22 As long as the conductivity σ is higher 22 Conductivity σ 21 Ratio of σ 21 / σ 22 is not limited to a specific value. 21 / σ 22 For example, the number is 10 or more, and 20 or more. The ratio σ may be 0.01 or more, 30 or more, or 50 or more. 21 / σ22 is, for example, 1000 or less, may be 800 or less, or may be 500 or less.

[0018] The change pattern of the conductivity of the conductive porous body 20 in a specific direction is not limited to a specific pattern. Fig. 3 is a graph showing the relationship between the conductivity of the conductive porous body 20 and the distance from the second end 22 in a specific direction. In Fig. 3, 20 is the distance of the first end 21 from the second end 22 in the specific direction. As shown in FIG. 3, the conductive porous body 20 has, for example, a conductivity that increases continuously or stepwise from the second end 22 to the first end 21 in the specific direction. With this configuration, the tactile sensor 1a is more likely to have the desired sensitivity and spatial resolution. The conductive porous body 20 may have, for example, a portion between the first end 21 and the second end 22 in the specific direction that has a conductivity that decreases toward the first end 21. The conductive porous body 20 may have a conductivity that increases continuously or stepwise from the first end 21 to the second end 22 in the specific direction. With this configuration, the linearity of the tactile sensor 1a can be increased.

[0019] As shown by the solid line in the graph of Fig. 3, the conductivity of the conductive porous body 20 can increase continuously from the second end 22 to the first end 21 in a specific direction. Fig. 4 shows an example of a conductive porous body 20 having such conductivity. In this example, for example, the porosity of the conductive porous body 20 changes continuously from the second end 22 to the first end 21 in a specific direction.

[0020] As shown by the dashed line in the graph of FIG. 3, the conductivity of the conductive porous body 20 can increase stepwise from the second end 22 to the first end 21 in a specific direction. FIG. 5 shows an example of a conductive porous body 20 having such conductivity. In this example, the conductive porous body 20 includes, for example, a plurality of porous body layers 23. The plurality of porous body layers 23 include, for example, a first porous body layer 23a, a second porous body layer 23b, and a third porous body layer 23c. The first porous body layer 23a forms the second end 22. The second porous body layer 23b forms the first end 21. The third porous body layer 23c is disposed between the first porous body layer 23a and the second porous body layer 23b in the specific direction. The conductivity of the first porous body layer 23a, the conductivity of the second porous body layer 23b, and the conductivity of the third porous body layer 23c can be considered to be constant in each porous body layer. For example, the electrical conductivity of the third porous body layer 23c is higher than that of the first porous body layer 23a and lower than that of the second porous body layer 23b. For example, the porosity of the third porous body layer 23c is lower than that of the first porous body layer 23a and higher than that of the second porous body layer 23b.

[0021] 5, the conductive porous body 20 has a laminated structure including, for example, a plurality of porous body layers 23 and a bonding layer 24. The bonding layer 24 is disposed between the porous body layers 23 in a specific direction and has conductivity. With such a configuration, it is easy to manufacture the conductive porous body 20 having desired characteristics by adjusting the conductivity and number of the plurality of porous body layers included in the laminated structure. The bonding layer 24 may be omitted.

[0022] The conductivity of the bonding layer 24 is not limited to a specific value as long as the bonding layer 24 is conductive. The bonding layer 24 has a conductivity of, for example, 0.001 to 10,000 S / m. With this configuration, the tactile sensor 1a is more likely to have the desired sensitivity and spatial resolution.

[0023] In the conductive porous body 20, the material that forms the porous structure is not limited to a specific material. The material is, for example, a composite material of a resin and a conductive filler. In this composite material, the resin can form the matrix. With such a configuration, the tactile sensor 1a is likely to have the desired flexibility. The resin that forms the matrix in the composite material is not limited to a specific resin. The resin may be a thermoplastic resin, a thermosetting resin, or a thermoplastic elastomer. The resin may be a mixture of a thermoplastic resin and a thermoplastic elastomer. It is also possible.

[0024] The shape of the conductive filler in the composite material is not limited to a specific shape, and may be, for example, spherical, flake, dendritic, or fibrous. Examples of the conductive filler are metal filler, metal-coated resin filler, carbon nanotube, graphite, and carbon black. Examples of the shape of graphite are, for example, scale-like, needle-like, fibrous, spherical, flake-like, agglomerate, and porous. Examples of the metal filler are copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder.

[0025] The shape of the conductive porous body 20 is not limited to a specific shape. For example, the conductive porous body 20 has a shape in which the first end 21 and the second end 22 are parallel to each other. The conductive porous body 20 may be in the form of a plate or sheet having a predetermined thickness. The thickness of the conductive porous body 20 is, for example, 0.5 to 20 mm. With such a configuration, the conductive porous body 20 is likely to have flexibility suitable for a sensor member. In this case, the specific direction may correspond to, for example, the thickness direction of the conductive porous body 20.

[0026] There is no particular limitation to the method for producing the conductive porous body 20. The conductive porous body 20 may be produced by a method using a physical foaming agent, a chemical foaming agent, or a thermal expansion capsule.

[0027] The conductor 30 in the tactile sensor 1a is not limited to a specific conductor. The conductor 30 has, for example, flexibility. The shape of the conductor 30 is not limited to a specific shape. The shape of the conductor 30 is, for example, a plate shape or a sheet shape.

[0028] 1 and 2A, the conductor 30 covers at least a part of the porous resin body 20. The conductor 30 may cover the entire porous resin body 20.

[0029] The electrical conductivity of the conductor 30 is not limited to a specific value, and is, for example, 0.01 to 100 S / m.

[0030] The material of the bonding layer 24 is not limited to a specific material as long as the bonding layer 24 can bond the porous layers 23 together. The bonding layer 24 is made of, for example, an adhesive material containing a conductive filler. The bonding layer 24 may be made of an adhesive tape having a base material, or may be made of an adhesive material without a base material. The bonding layer 24 may be formed of a conductive adhesive containing a conductive filler.

[0031] As shown in FIG. 2A, the tactile sensor 1a further includes, for example, an insulator 40. The insulator 40 is disposed between the conductive porous body 20 and the conductor 30 in a specific direction. In addition, the insulator 40 forms a gap 42 extending in a specific direction. With this configuration, when an object contacts at least one of the conductive porous body 20 and the conductor 30, the conductive porous body 20 and the conductor 30 may come into contact with each other in the gap 42 near the contact portion with the object. On the other hand, in the gap 42 away from the contact portion with the object, the conductive porous body 20 and the conductor 30 do not come into contact with each other. For this reason, the difference between the potential at the electrode 10 near the contact portion with the object and the potential at the electrode 10 away from the contact portion with the object tends to be large, and the tactile sensor 1a tends to have the desired sensitivity and spatial resolution. The insulator 40 may be omitted.

[0032] As shown in FIG. 1, the tactile sensor 1a includes a laminate 5 including, for example, a conductive porous body 20, a conductor 30, and an insulator .

[0033] The insulator 40 may be disposed directly on the conductor 30 in a dot or mesh form. The material constituting the body 40 is not limited to a specific material. The insulator 40 may be, for example, a porous body made of an insulating material, a mesh made of an insulating material, a woven fabric made of an insulating material, or a nonwoven fabric made of an insulating material. The insulator 40 has, for example, a plate-like or sheet-like shape. In this specification, the insulator is defined as a body having a diameter of 1.0×10 -15 S / m or less It is a material that has electrical conductivity.

[0034] 1, the arrangement of the multiple electrodes 10 in the tactile sensor 1a is not limited to a specific arrangement as long as the multiple electrodes 10 are in contact with the conductive porous body 20. As shown in FIG. 2A, the multiple electrodes 10 are in contact with the second end 22, for example.

[0035] On the other hand, tactile sensor 1a may be modified to tactile sensor 1b shown in FIG. 6. Tactile sensor 1b is configured similarly to tactile sensor 1a, except for parts that will be particularly described. The same reference numerals are used to designate components of tactile sensor 1b that are the same as or correspond to the components of tactile sensor 1a, and detailed description will be omitted. The description of tactile sensor 1a also applies to tactile sensor 1b, except where there is a technical contradiction. This also applies to other modified examples.

[0036] 6, the multiple electrodes 10 are disposed in a specific direction between a first end 21 and a second end 22. In other words, the multiple electrodes 10 are embedded inside the conductive porous body 20.

[0037] The arrangement of the multiple electrodes 10 in the plan view of the tactile sensor 1a is not limited to a specific arrangement. In the plan view of the tactile sensor 1a, the multiple electrodes 10 may be arranged regularly or irregularly. As shown in FIG. 1, in the plan view of the tactile sensor 1a, the multiple electrodes 10 are arranged, for example, at lattice points of a square lattice. The multiple electrodes 10 may also be arranged at lattice points of other planar lattices such as a rectangular lattice and a parallelogram lattice. The multiple electrodes 10 may be arranged along the outer periphery of the tactile sensor 1a in the plan view of the tactile sensor 1a.

[0038] In addition, in a plan view of the tactile sensor 1a, the multiple electrodes 10 may be arranged as shown in Fig. 7. In this case, each of the multiple electrodes 10 is arranged so as to be randomly shifted within a predetermined range from each lattice point of the planar lattice. With such a configuration, the contact state of the object can be appropriately measured regardless of the contact position of the object with at least one of the conductive porous body 20 and the conductor 30. In addition, the degree of freedom in the arrangement of the multiple electrodes 10 is easily ensured.

[0039] In tactile sensor 1a, for example, measurement unit 50 selectively grounds one or more of the multiple electrodes 10 and sequentially switches between the grounded electrodes 10 to measure the contact state of an object. In this case, spatial performance and temporal performance change depending on the number of times the ground is switched, and in tactile sensor 1a, the more the number of times the ground is switched, the higher the spatial resolution and the lower the temporal resolution tends to be.

[0040] 8, in the tactile sensor 1a, the multiple electrodes 10 include, for example, multiple electrode groups 15. Each of the multiple electrode groups 15 has two or more electrodes 10. The measurement unit 50 simultaneously grounds the multiple electrodes 10, each of which is composed of one electrode 10 selected from the multiple electrode groups 15, and measures the contact state of the object by sequentially switching the electrodes 10 to be grounded in each of the multiple electrode groups 15. With this configuration, it is easier to improve the time resolution of the measurement of the contact state of the object compared to measuring the contact state of the object by sequentially switching the electrodes to be grounded one by one in the multiple electrodes 10.

[0041] According to the tactile sensor 1a, the plurality of electrodes 10 includes, for example, a first electrode group 15a, a second electrode group 15b, a third electrode group 15c, and a fourth electrode group 15d. For example, each electrode group 15 has four electrodes 10a, 10b, 10c, and 10d. In each electrode group 15, the four electrodes 10a, 10b, 10c, and 10d are arranged at the vertices of a predetermined quadrangle such as a square or a rectangle. The number of electrodes 10 included in each electrode group 15 may be three, or may be five or more.

[0042] 9 shows an example of the circuit of the measurement unit 50. The measurement unit 50 includes, for example, a switching circuit 52 and a control circuit 51. The switching circuit 52 includes, for example, 16 wires 52a to 52p and five multiplexers M1 to M5. The wires 52a, 52b, 52c, and 52d are electrically connected to the electrodes 10a, 10b, 10c, and 10d of the first electrode group 15a, respectively. The wires 52e, 52f, 52g, and 52h are electrically connected to the electrodes 10a, 10b, 10c, and 10d of the second electrode group 15b, respectively. The wires 52i, 52j, 52k, and 52l are electrically connected to the electrodes 10a, 10b, 10c, and 10d of the third electrode group 15c, respectively. The wirings 52m, 52n, 52o, and 52p are electrically connected to the electrodes 10a, 10b, 10c, and 10d of the fourth electrode group 15d, respectively. The wirings 52a to 52p are connected to a multiplexer M1. Each of the 16 wirings 52a to 52p branches between the electrode 10 and the multiplexer M1. The wirings branched from the wirings 52a to 52d are connected to the multiplexer M2. The wirings branched from the wirings 52e to 52h are connected to the multiplexer M3. The wirings branched from the wirings 52i to 52l are connected to the multiplexer M4. The wirings branched from the wirings 52m to 52p are connected to the multiplexer M5. The multiplexers M2, M3, M4, and M5 are each grounded. The multiplexer M1 may be omitted by connecting the 16 wires directly to the individual A / D converters ADC.

[0043] As a digital output (DO) signal is input from the control unit 51 to the multiplexer M1, electrical signals corresponding to the potentials of each of the electrodes 10 connected to the 16 wirings 52a to 52p are input sequentially to the A / D converter ADC of the control circuit 51.

[0044] As the digital output (DO) signal is input from the control unit 51 to each of the multiplexers M2, M3, M4, and M5, one of the four wires connected to these multiplexers is selectively grounded. As a result, for example, the electrodes 10a of each electrode group 15 are grounded simultaneously. Next, the electrodes 10b of each electrode group 15 are grounded simultaneously. Next, the electrodes 10c of each electrode group 15 are grounded simultaneously. Next, the electrodes 10d of each electrode group 15 are grounded simultaneously. Thereafter, the grounding of the electrodes 10a, 10b, 10c, and 10d is repeated in sequence.

[0045] In the tactile sensor 1a, multiple electrode groups 15 may be configured as shown in Fig. 10. In this example, the multiple electrode groups 15 have two or more electrodes 20 arranged in a row in a predetermined direction. For example, in each electrode group 15, four electrodes 10a, 10b, 10c, and 10d are arranged in a row in a predetermined direction. In addition, the multiple electrode groups 15 are arranged parallel to each other in a plan view.

[0046] In the tactile sensor 1a, when an object comes into contact with at least one of the conductive porous body 20 and the conductor 30, the tactile sensor 1a produces an output corresponding to the contact state. It is also assumed that the tactile sensor 1a is used in a state in which the conductive porous body 20 is arranged along a curved surface or in a state in which it is bent by applying a force. Alternatively, it is also conceivable that the conductive porous body 20 is arranged along a bendable member. The rate of variation of the output of the tactile sensor 1a accompanying the variation of the arrangement state of the conductive porous body 20 is not limited to a specific value. For example, the output of the tactile sensor 1a in a bent state exhibits a variation of 10% or less compared to the output of the tactile sensor 1a in a flat state.

[0047] In the tactile sensor 1a, for example, the output fluctuation rate shown in formula (1) is 10% or less. In formula (1), the first output is the output of the tactile sensor 1a under specific conditions when the conductive porous body 20 is placed along a flat surface. The second output is the output of the tactile sensor 1a under specific conditions when the conductive porous body 20 is fixed along a curved surface having a curvature radius of 30 mm. The specific condition is, for example, applying a predetermined external force to the tactile sensor 1a and releasing the external force. Output fluctuation rate = 100 × |Second output - First output| / First output Formula (1)

[0048] In the tactile sensor 1a, when the above-mentioned output fluctuation rate is 10% or less, the tactile sensor 1a is likely to have the desired sensitivity and spatial resolution even when the conductive porous body 20 is arranged along a curved surface or when the conductive porous body 20 is arranged along a bendable member.

[0049] The tactile sensor 1a may be modified as a tactile sensor 1c shown in FIG. 11. The tactile sensor 1c includes a gripper 7 including an elastomer. The conductive porous body 20 is arranged along the gripper 7. As shown in FIG. 11, for example, a laminate 5 including the conductive porous body 20 is arranged along the gripper 7. When the gripper 7 grips a predetermined object, deformation occurs in at least one of the conductive porous body 20 and the conductor 30 due to contact between the gripper 7 and the predetermined object, and the contact resistance between the conductive porous body 20 and the conductor 30 may vary. This may cause the potential of the multiple electrodes 10 to vary. The measuring unit 50 can measure the contact state of the object with at least one of the conductive porous body 20 and the conductor 30, which corresponds to the contact state between the gripper 7 and the predetermined object, based on the potential of the multiple electrodes 10.

[0050] The gripper 7 contains an elastomer, and therefore is easily deformed and is unlikely to damage an article that comes into contact with the gripper 7. Therefore, the gripper 7 can grasp a variety of articles without damaging them.

[0051] As long as the gripper 7 contains an elastomer, the shape of the gripper 7 is not limited to a specific shape. As shown in FIG. 11, the gripper 7 has, for example, a plurality of grooves 72 formed parallel to each other. This allows the gripper 7 to bend easily and to grasp an article easily. The conductive porous body 20 can deform in accordance with the deformation of the gripper 7. The plurality of electrodes 10 are formed on, for example, a flexible substrate.

[0052] The method for manufacturing the tactile sensor 1a is not limited to a specific method. 22 Higher conductivity σ 21 The method includes positioning the conductive porous body 20 such that the first end 21 having the conductive body 30 is located between the conductive body 30 and the second end 22. EXAMPLES

[0053] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0054] <Calculation example> Calculations were performed to evaluate the indices indicating the sensitivity, linearity, and spatial resolution in the calculation model M simulating the tactile sensor shown in Figures 12A, 12B, and 12C. The calculation model M had 16 first parts E simulating a plurality of electrodes 10, a second part P simulating a conductive porous body 20, and a third part D simulating a conductor 30. The second part P was a flat plate having a thickness of 10 mm, and had a square shape with a side length of 60 mm in a plan view. The first part E was cylindrical with a diameter of 4 mm, and the 16 first parts E were evenly arranged so as to line up on the lattice points of a square lattice on one main surface of the second part P. The third part D was cylindrical with a diameter of 4 mm, and was arranged at the center of the other main surface of the second part P. The third part The potential condition of the third part D was set under the condition that a certain DC voltage was applied to D. In addition, in order to reproduce the change in the load applied to the calculation model M, the conductivity of the third part D was changed and calculations were performed. In the calculation model M, the conductivity σP In the thickness direction, the following formula is satisfied: We assume that the distributions are exponential functions (2) and (3). In equation (2), σ low is conductive is the lower limit of the rate, σ up In the formulas (2) and (3), y indicates the position of the second portion P in the thickness direction. min is a thickness direction of the second portion P. Limit σ low y indicates the position corresponding to max is the upper limit value σ in the thickness direction of the second portion P up Indicates the corresponding position. σ P = σ low (σ up / σ low ) α Formula (2) α = (yy min ) / (y max -y min ) Formula (3)

[0055] An upper limit value σ selected from the group consisting of 0.001 S / m, 0.01 S / m, 0.1 S / m, 1 S / m, 10 S / m, and 100 S / m. up and the lower limit σ up For all combinations of the above, the potential in the calculation model M when the conductivity of the third site D was changed was numerically obtained according to the finite element method. From the potential data thus obtained, a group of data showing the relationship between the conductivity of the third site D and the voltage at the electrode E was obtained, as shown in FIG. 13A. Furthermore, a regression line of this group of data was determined according to the least squares method. The slope of this regression line was used as an index of sensitivity. Furthermore, the residual between the regression line and the value of the group of data was obtained. This residual was used as an index of linearity.

[0056] From the data on the potential on one principal surface of the second region P, the distribution of the potential on one principal surface of the second region P when the conductivity of the third region D is a predetermined value was obtained as shown in Fig. 13B. In this distribution, the third region D was located directly above the position of 0.5. The half-width of this potential distribution was used as an index of spatial resolution.

[0057] 14A, 14B, and 14C respectively show evaluation results of the sensitivity, linearity, and spatial resolution based on the calculation results using the calculation model M. The bottom of the second portion P corresponds to one of the main surfaces of the second portion P, and the top of the second portion P corresponds to the other main surface of the second portion P.

[0058] According to Figures 14A, 14B, and 14C, it can be seen that, for example, when the conductivity of the bottom of the second portion P is close to 0.001 S / m and the conductivity of the top of the second portion P is close to 0.1 S / m, the sensitivity, linearity, and spatial resolution are likely to be high.

[0059] <Sample 1> A porous sheet A1 having a thickness of 5 mm was prepared from conductive rubber sponge E-4385 manufactured by Inoac Corporation. E-4385 is a foam whose main component is ethylene propylene rubber. The surface resistivity of the porous sheet A1 is 3.8×10 2 The surface resistivity of the porous sheet B1 was 1.2×10 5 The surface resistivity of the bonding layer formed by the conductive adhesive 9707 was 0.5 Ω / sq. The porous sheet B1 was a square with one side measuring 60 mm in plan view. One main surface of the porous sheet A1 and one main surface of the porous sheet B1 were bonded together with conductive adhesive 9707 manufactured by 3M to produce a conductive porous body according to Sample 1. The thickness of the conductive porous body according to Sample 1 was 10.15 mm. The surface resistivity of the bonding layer formed by the conductive adhesive 9707 was 0.5 Ω / sq. The conductivity of the conductive adhesive 9707 was 2.0 S / m. The electrical conductivity of the main surface formed by the porous sheet A1 of the conductive porous body of Sample 1 was 0.52 S / m, and the electrical conductivity of the main surface formed by the porous sheet B1 of the conductive porous body of Sample 1 was 1.7×10 -3 S / m.

[0060] The conductive porous body of Sample 1 was placed on an electrode substrate having 16 electrodes, and the conductive porous body and the electrodes were bonded together with a conductive adhesive CW2401 provided by Circuit Works. The conductive porous body and the electrode were bonded so that the electrode B1 was in contact with the electrode. Each electrode of the electrode substrate was connected to a measurement circuit. The measurement circuit was composed of a microcontroller ESP-WROOM-32 provided by Espressif System and a multiplexer ADG726 provided by Analog Devices. The microcontroller was configured to be able to communicate with a computer. The multiplexer was configured to be able to select an electrode to be grounded from among the 16 electrodes of the electrode substrate by a digital signal output from the microcontroller. In this manner, an evaluation sensor relating to Sample 1 was produced.

[0061] The measurement circuit was configured to acquire 256 pieces of data to estimate one pressure distribution. The 256 pieces of data correspond to combinations of 16 electrodes and 16 conditions related to the grounding of the electrodes. Based on the data acquired by the measurement circuit, a finite element analysis of the electric potential distribution was performed in a computer. In this finite element analysis, a two-dimensional mesh model was prepared. This two-dimensional mesh model was defined by approximately 4,000 triangular elements and approximately 2,000 nodes. This two-dimensional mesh model included elements corresponding to the electrodes.

[0062] The evaluation sensor for Sample 1 was fixed on the XY stage. Furthermore, a force sensor USL06-H5-50N-A manufactured by Tech Gihan Co., Ltd. and an indenter with a diameter of 10 mm were attached to a linear actuator DRLM42G-04A2P-K manufactured by Oriental Motor Co., Ltd. A silicone rubber pad with a diameter of 5 mm was attached to the tip of the indenter. A conductive rubber was attached and a DC voltage of 3.3 V was applied to use it as a driving layer (conductor). An indenter was brought close to the conductive porous body of the evaluation sensor at a speed of 0.5 mm / sec to contact the center of the porous sheet A1 of the conductive porous body, and a load in the range of 0 to 5 N was applied. At this time, a voltage from a DC power source was applied to the contact. Based on the measurement results of the evaluation sensor, an estimated value of the voltage at the electrode at the center of the electrode substrate and an estimated value of the voltage on the straight line (center line) passing through the center of the porous sheet A1 in the conductive porous body were obtained. An example of the results is shown in Figures 15A and 15B.

[0063] FIG. 15A is a graph showing the relationship between the load and the output voltage corresponding to the center of the load in the evaluation sensor. The sensitivity was evaluated based on the shape of this graph. The results are shown in Table 1. According to FIG. 15A, the sensitivity of sample 1 was 2.6×10 -3 V / N. and linearity were evaluated as "high" and "medium", respectively. Figure 15B is a graph showing the relationship between the normalized output on the center line passing through the center of the load in the evaluation sensor and the position on that center line. This graph was used to evaluate the spatial resolution. If a steep peak is confirmed in this graph, the spatial resolution is evaluated as high. From the shape of this graph, the spatial resolution was evaluated as half-width. The results are shown in Table 1. According to Figure 15B, the spatial resolution of sample 1 was evaluated as 0.19. In Table 1, the lower surface is the main surface on the electrode side of the conductive porous body.

[0064] <Sample 2> A porous sheet A2 having a thickness of 5 mm was prepared from conductive rubber sponge E-4385 manufactured by Inoac Corporation. E-4385 is a foam whose main component is ethylene propylene rubber, and the surface resistivity of the porous sheet A2 is 3.8×10 2 The surface resistivity of the porous sheet B2 was 1.2×10 5Ω / sq. The porous sheet B2 was a square with one side measuring 60 mm in plan view. A dot pattern consisting of perfect circles with a diameter of 2 mm was arranged at equal intervals of 5 x 5 using conductive adhesive CN7120 manufactured by Kaken Tech Co., Ltd. to form a bonding surface, and one main surface of the porous sheet A2 and one main surface of the porous sheet B2 were bonded to each other. In this way, a conductive porous body according to sample 2 was produced. Sample The thickness of the conductive porous body according to Example 2 was 10.15 mm. The surface resistivity of each bonding layer formed with the conductive adhesive was 4.0×10 -4 The conductivity of this conductive adhesive was Ω / sq. The rate is 2.5 x 10 3 S / m. Conductive porous sheet A2 according to sample 2 The conductivity of the main surface formed by the porous sheet B2 of the conductive porous body of Sample 2 was 0.52 S / m, and the conductivity of the main surface formed by the porous sheet B2 of the conductive porous body of Sample 2 was 1.7 × 10 -3 S / m.

[0065] An evaluation sensor according to Sample 2 was produced in the same manner as Sample 1, except that the conductive porous body according to Sample 2 was used instead of the conductive porous body according to Sample 1. In addition, the sensitivity, linearity, and spatial resolution of the evaluation sensor according to Sample 2 were evaluated in the same manner as the evaluation sensor according to Sample 1. The evaluation results are shown in Table 1.

[0066] <Sample 3> Perforated sheets with a thickness of 2.5 mm were prepared from E-4385, conductive silicone sponge sheet Si-500 manufactured by Shibata Kogyo Co., Ltd., conductive polyurethane foam F-10 manufactured by Hozan Co., Ltd., and TK-2. Each perforated sheet was a square with one side measuring 60 mm in plan view. The surface resistivity of the perforated sheet A3 made from E-4385 was 6.6×10 2 The surface resistivity of the porous sheet B3 made from TK-2 was 1.3×10 5 The surface resistivity of the porous sheet C3 made from Si-500 was 4.2×10 2The surface resistivity of the porous sheet D3 made from F-10 was 2.5×10 4 Ω / sq. A bonding surface in which a dot pattern consisting of perfect circles with a diameter of 2 mm was arranged at equal intervals of 5×5 was formed using conductive adhesive CN7120, and one main surface of the porous sheet A2 and one main surface of the porous sheet C3 were bonded. A bonding surface in which a dot pattern consisting of perfect circles with a diameter of 2 mm was arranged at equal intervals of 5×5 was formed using conductive adhesive CN7120, and the other main surface of the porous sheet C3 and one main surface of the porous sheet D3 were bonded. A bonding surface in which a dot pattern consisting of perfect circles with a diameter of 2 mm was arranged at equal intervals of 5×5 was formed using conductive adhesive CN7120, and the other main surface of the porous sheet D3 and one main surface of the porous sheet B3 were bonded. The surface resistivity of each bonding layer formed by the conductive adhesive was 4.0×10 -4 The electrical conductivity of this conductive adhesive was 2.5×10 3 In this manner, the conductive porous body according to Sample 3 was produced. The conductive porous body according to Sample 3 had a principal surface formed by the porous sheet A3 with a conductivity of 0.30 S / m, and the conductive porous body according to Sample 3 had a principal surface formed by the porous sheet B3 with a conductivity of 1.5×10 -3 S / m.

[0067] An evaluation sensor according to Sample 3 was produced in the same manner as Sample 1, except that the conductive porous body according to Sample 3 was used instead of the conductive porous body according to Sample 1. In addition, the sensitivity, linearity, and spatial resolution of the evaluation sensor according to Sample 3 were evaluated in the same manner as the evaluation sensor according to Sample 1. The evaluation results are shown in Table 1.

[0068] <Sample 4> A porous sheet E4 having a thickness of 5 mm was prepared from conductive rubber sponge C-4255 manufactured by INOAC Corporation. C-4255 is a foam whose main component is chloroprene rubber. The porous sheet E4 had a square shape with one side measuring 60 mm in plan view. The surface resistivity of the porous sheet E4 was 8.8×10 2Ω / sq. An evaluation sensor for Sample 4 was produced in the same manner as Sample 1, except that the porous sheet E4 was used instead of the conductive porous body for Sample 1. In addition, the sensitivity, linearity, and spatial resolution of the evaluation sensor for Sample 4 were evaluated in the same manner as the evaluation sensor for Sample 1. The evaluation results are shown in Table 1.

[0069] <Sample 5> A porous sheet A5 having a thickness of 5 mm was produced from E-4385. The porous sheet A5 had a square shape with one side having a length of 60 mm in a plan view. The surface resistivity of the porous sheet A5 was 3.8×10 2 Ω / sq. An evaluation sensor for Sample 5 was produced in the same manner as Sample 1, except that the porous sheet A5 was used instead of the conductive porous body for Sample 1. In addition, the sensitivity, linearity, and spatial resolution of the evaluation sensor for Sample 5 were evaluated in the same manner as the evaluation sensor for Sample 1. The evaluation results are shown in Table 1.

[0070] <Sample 6> A porous sheet B6 having a thickness of 5 mm was produced from TK-2. The porous sheet B6 had a square shape with one side having a length of 60 mm in a plan view. The surface resistivity of the porous sheet B6 was 1.2×10 5 Ω / sq. An evaluation sensor for Sample 6 was produced in the same manner as Sample 1, except that the porous sheet B6 was used instead of the conductive porous body for Sample 1. In addition, the sensitivity, linearity, and spatial resolution of the evaluation sensor for Sample 6 were evaluated in the same manner as the evaluation sensor for Sample 1. The evaluation results are shown in Table 1.

[0071] <Sample 7> A porous sheet C7 having a thickness of 5 mm was prepared from Si-500. The porous sheet C7 had a square shape with one side having a length of 60 mm in a plan view. The surface resistivity of the porous sheet C7 was 2.2×10 3Ω / sq. An evaluation sensor for Sample 7 was produced in the same manner as Sample 1, except that the porous sheet C7 was used instead of the conductive porous body for Sample 1. In addition, the sensitivity, linearity, and spatial resolution of the evaluation sensor for Sample 7 were evaluated in the same manner as the evaluation sensor for Sample 1. The evaluation results are shown in Table 1.

[0072] As shown in Table 1, it is understood that the sensitivity and spatial resolution of the evaluation sensor for Sample 1 are higher than those of the evaluation sensors for Samples 5 and 7 in which a single-layer porous sheet was used as the conductive porous body. In addition, it is understood that the spatial resolution of the evaluation sensor for Sample 1 is higher than that of the evaluation sensor for Sample 6.

[0073] <Sample 8> A flexible electrode substrate was prepared in which 16 electrodes having a diameter in plan view were arranged in two rows. The flexible electrode substrate was rectangular in plan view, and 16 electrodes were arranged in two rows in a rectangular area having a long side of 60 mm and a short side of 13 mm. Perforated sheets E8 with thicknesses of 2 mm, 3 mm, and 5 mm were prepared from conductive rubber sponge C-4255 manufactured by Inoac Corporation. The perforated sheet E8 was rectangular in plan view, having a long side of 60 mm and a short side of 15 mm. The perforated sheet E8 was placed on the 16 electrodes of the flexible electrode substrate. Conductive silicone rubber Sirius 10547 and perforated sheet Between E8, install insulating glass fiber adhesive tape 13-7194 manufactured by Kyokuto Sanki Co., Ltd. The sheet E8 and the conductive silicone rubber were joined. Each electrode of the flexible electrode substrate was connected to a measurement circuit. In this manner, an evaluation sensor relating to Sample 8 was produced. The measurement circuit was composed of a microcontroller ESP-WROOM-32 provided by Espressif System, and multiplexers ADG709 and ADG707 provided by Analog Devices. The microcontroller was configured to be able to communicate with a computer. The multiplexer ADG709 was configured to be able to select an electrode to be grounded among the 16 electrodes by a digital signal output from the microcontroller. The multiplexer ADG709 was configured to simultaneously ground four electrodes among the 16 electrodes and sequentially switch the electrodes to be grounded. The multiplexer ADG707 was configured to switch the electrodes to be measured for potential.

[0074] In the evaluation sensor of sample 8, the measurement circuit was configured to acquire 64 pieces of data to estimate one pressure distribution. The 64 pieces of data consisted of combinations of 16 electrodes and four conditions related to the grounded electrode. The data was updated every 24 milliseconds. The new frequency was acquired and transferred to the computer.

[0075] The evaluation sensor for sample 8 was fixed so that the porous sheet E8 of the evaluation sensor was aligned along a flat surface. A force sensor USL06-H5-50N-A manufactured by Kubota Engineering and an indenter with a diameter of 10 mm were attached. The indenter was brought close to the conductive silicone rubber of the evaluation sensor at a speed of 0.5 mm / sec and brought into contact with a predetermined portion of the conductive silicone rubber, and a load in the range of 0 to 6 N was applied. At this time, a voltage from a DC power source was applied to the conductive silicone rubber. Based on the measurement results of the evaluation sensor related to sample 8, a graph α was obtained showing the relationship between the output voltage corresponding to the center of the load in the evaluation sensor and the load.

[0076] The porous sheet E8 of the evaluation sensor relating to Sample 8 was fixed along a concave curved surface having a curvature radius of 28.65 mm. A force sensor USL06-H5-50N-A manufactured by Tech Gihan Co., Ltd. and an indenter with a diameter of 10 mm were attached to a linear actuator DRLM42G-04A2P-K manufactured by Oriental Motor Co., Ltd. The indenter was brought close to the conductive silicone rubber of the evaluation sensor at a speed of 0.5 mm / sec to contact a predetermined portion of the conductive silicone rubber, and a load in the range of 0 to 6 N was applied. At this time, a voltage was applied from a DC power source to the conductive silicone rubber. Based on the measurement results of the evaluation sensor related to sample 8, a graph β was obtained that shows the relationship between the load and the output voltage corresponding to the center of the load in the evaluation sensor.

[0077] Based on the output in graph α and the output in graph β, the output fluctuation rate was calculated from the following formula (4): As a result, the output fluctuation rate of the evaluation sensor related to sample 8 was 10% or less. Output fluctuation rate = 100 × |Output in graph β - Output in graph α| / Output in graph α Equation (4)

[0078] <Sample 10> A porous sheet E10 having a thickness of 5 mm was prepared from the conductive rubber sponge C-4255. The porous sheet E10 had a rectangular shape with a long side of 60 mm and a short side of 15 mm in plan view. An evaluation sensor for sample 10 was prepared in the same manner as sample 8, except that the porous sheet E10 was used instead of the porous sheet E8, and the output fluctuation rate was obtained. As a result, the output fluctuation rate of the evaluation sensor for sample 10 was 10% or less.

[0079] [Table 1] [Explanation of symbols]

[0080] 1a, 1b, 1c Tactile sensors 7 Gripper 10 electrodes 15 electrode group 20 Conductive porous body 21 First end 22 Second end 24 Bonding layer 30 Conductors 40 Insulators 50 Measurement section

Claims

1. A plurality of electrodes; A conductive porous body in contact with the plurality of electrodes and having different electrical conductivities in a specific direction; a conductor disposed apart from the conductive porous body in the specific direction; a measuring unit that measures a contact state of an object with at least one of the conductive porous body and the conductor based on the potentials of the plurality of electrodes; the conductive porous body has a first end portion formed at one end on the conductor side in the specific direction and a second end portion formed at the other end in the specific direction, The electrical conductivity at the first end of the conductive porous body is higher than the electrical conductivity at the second end of the conductive porous body. Tactile sensor.

2. The tactile sensor according to claim 1 , further comprising an insulator disposed between the conductive porous body and the conductor in the specific direction and forming a gap extending in the specific direction.

3. 3. The tactile sensor according to claim 1, wherein the conductive porous body has a conductivity that varies in the range of 0.001 to 100 S / m in the specific direction.

4. The tactile sensor according to any one of claims 1 to 3, wherein the conductive porous body has a conductivity that increases continuously or stepwise from the second end to the first end in the specific direction.

5. The conductive porous body has a laminated structure, The laminated structure includes a plurality of porous body layers arranged in the specific direction, and a conductive bonding layer arranged between the porous body layers in the specific direction. The tactile sensor according to any one of claims 1 to 4.

6. The tactile sensor according to claim 5 , wherein the bonding layer has a conductivity of 0.001 to 10,000 S / m.

7. The tactile sensor according to any one of claims 1 to 6, wherein the plurality of electrodes are in contact with the second end or are arranged between the first end and the second end in the specific direction.

8. The tactile sensor according to any one of claims 1 to 7, wherein the measurement unit selectively grounds one or more of the plurality of electrodes and measures the contact state by sequentially switching between the electrodes to be grounded.

9. the plurality of electrodes includes a plurality of electrode groups each having two or more electrodes; the measurement unit simultaneously grounds a plurality of electrodes, each of which is one selected from a plurality of electrode groups, and measures the contact state by sequentially switching the electrodes to be grounded in each of the plurality of electrode groups. The tactile sensor according to any one of claims 1 to 8.

10. 10. The tactile sensor according to claim 1, wherein an output of the tactile sensor in a bent state varies by 10% or less with respect to an output of the tactile sensor in a flat state.

11. a gripper including an elastomer; The tactile sensor according to claim 1 , wherein the conductive porous body is disposed along the gripper.

12. A method for manufacturing a tactile sensor, comprising the steps of: The tactile sensor includes: A plurality of electrodes; A conductive porous body in contact with the plurality of electrodes and having different electrical conductivities in a specific direction; a conductor disposed apart from the conductive porous body in the specific direction; a measuring unit that measures a contact state of an object with at least one of the conductive porous body and the conductor based on the potentials of the plurality of electrodes; The method includes arranging the conductive porous body such that a first end portion, which is formed at one end of the conductive porous body on the side of the conductor in the specific direction and has a higher electrical conductivity than a second end portion of the conductive porous body formed at the other end in the specific direction, is located between the conductor and the second end portion. Manufacturing method.

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