JP6943480B2 - Tactile sensor - Google Patents

Description

The present invention relates to an inductance measurement type tactile sensor that detects deformation of a thick flexible material.

When giving a deformation detection function to a thick flexible material, it is an issue to achieve both durability and sensitivity of the deformation detection function. For example, if the wiring and the sensor element are embedded in the thick flexible material, the wiring and the sensor element are easily destroyed when the thick flexible material is greatly deformed. However, if the wiring and the sensor element are arranged on the bottom surface of the thick flexible material in order to avoid easy destruction of the wiring and the sensor element, the sensitivity of the sensor element to minute deformation on the surface portion of the thick flexible material is impaired.

To solve this problem, a magnet is placed in the thick flexible material, and the movement of the magnet due to deformation of the thick flexible material is remotely detected by a magnetic detection sensor element placed on the bottom surface of the thick flexible material. Therefore, a tactile sensor that achieves both durability and sensitivity is known (Patent Document 1).

However, when the magnet is arranged as it is in the thick flexible material as in Patent Document 1, the tactile sensation to the thick flexible material is impaired. In order to avoid this problem, a tactile sensor that disperses magnets made of fine particles on the surface of a thick flexible material is known (Patent Document 2).

Further, there is known a tactile sensor in which a magnetic elastomer (thick flexible material) in which iron powder particles are dispersed is fixed to a frame, and a coil is arranged on the opposite side of the magnetic elastomer with the frame interposed therebetween (Non-Patent Document 1). ).

Japanese Unexamined Patent Publication No. 2011-153826 (published on August 11, 2011) JP-A-2015-202821 (published on November 16, 2015)

"Magnetic Tactile Sensor Using Magnetic Elastoma" Horii et al., Proceedings of the Japan Society of Mechanical Engineers Robotics and Mechatronics Lecture Proceedings May 21, 2014

However, the above-mentioned tactile sensor described in Patent Documents 1 and 2 has the following problems because the magnet is present in the thick flexible material.

First, it is difficult to manufacture a tactile sensor with a complicated shape such as a curved surface because a manufacturing process that aligns the magnetization direction of the material to be a magnet along the surface shape of the tactile sensor is indispensable for increasing the sensitivity of the tactile sensor. Is.

Further, since the amount of magnetic flux leaking to the outside of the tactile sensor is large, it is difficult to bring the tactile sensor into contact with an object that is weak against magnetism. Further, if there is a metal near the surface of the tactile sensor that is not in contact with the surface, the magnetic field changes according to the amount of magnetic flux leaking, so that the response of the tactile sensor changes.

Since a sensor that measures changes in magnetism is used, it is difficult to use it in a situation where the inclination of the sensor itself changes in the geomagnetism or in a situation where a magnet or an electric motor that emits a magnetic field is present nearby.

Further, the tactile sensor described in Non-Patent Document 1 detects a change in inductance due to particles dispersed in a magnetic elastoma being compressed by an external force and the particles approaching each other to increase the density. There is a problem that it is minute and the sensitivity of the tactile sensor is extremely low.

One aspect of the present invention is a highly sensitive tactile sensor that can easily realize a complicated shape, can be brought into contact with a magnetically sensitive object, and can be used even in an environment where an external magnetic field exists. The purpose is to provide.

In order to solve the above problems, the tactile sensor according to one aspect of the present invention has a first flexible layer formed on a base material and a magnetic permeability higher than the magnetic permeability of the first flexible layer. The second flexible layer formed so that the unmagnetized particles are dispersed and supported by the first flexible layer, and the particles formed on the base material by an external force acting on the second flexible layer. It is characterized by including one or more coils whose inductance changes based on displacement and a measurement circuit that measures a change in the inductance of the coil.

According to one aspect of the present invention, a highly sensitive tactile sensation that can easily realize a complicated shape, can be brought into contact with a magnetically sensitive object, and can be used even in an environment where an external magnetic field exists. A sensor can be provided.

(A) is a cross-sectional view of the tactile sensor according to the first embodiment, (b) is a bottom view thereof, and (c) is a diagram for explaining the inductance of a coil provided in the tactile sensor. (A) is a cross-sectional view showing the operating principle of the tactile sensor, (b) is a perspective view showing the appearance of the tactile sensor, and (c) is a substrate, a coil, and non-magnetic material provided on the tactile sensor. It is a perspective view which shows the flexible layer and the magnetic flexible layer. (A) is a perspective view showing the appearance of a prototype of the tactile sensor, (b) is a plan view showing a substrate provided on the tactile sensor, and (c) is a plan view showing a substrate provided on the substrate. It is a plan view, and (d) is a perspective view which shows the coil provided on the said substrate. It is a perspective view which shows the experimental apparatus of the above-mentioned tactile sensor. It is a graph which shows the relationship between the pushing depth of the indenter pushed into the tactile sensor, and the elapsed time. It is a graph which shows the relationship between the pressing force to the tactile sensor and the inductance of the coil. It is sectional drawing of the tactile sensor which concerns on Embodiment 2. FIG. (A) is a perspective view showing the appearance of the tactile sensor, and (b) is a perspective view showing a substrate, a coil, a non-magnetic flexible layer, and a magnetic flexible layer provided on the tactile sensor. It is a top view which shows typically the relationship between the coil provided in the tactile sensor, and a magnetic flexible layer. (A) is a graph showing the relationship between the displacement of the magnetic flexible layer in the Z-axis direction and the change in the inductance of the coil, and (b) is the vertical force applied to the magnetic flexible layer and the inductance of the coil. It is a graph which shows the relationship with the change of. It is a top view which shows typically the relationship between the coil provided in the tactile sensor, and the magnetic flexible layer which moves in a + X direction. (A) is a graph showing the relationship between the displacement of the magnetic flexible layer in the X-axis direction and the change in the inductance of the coil, and (b) is the shearing force applied to the magnetic flexible layer in the X-axis direction. It is a graph which shows the relationship with the change of the inductance of the coil. It is a top view which shows typically the relationship between the coil provided in the tactile sensor, and the magnetic flexible layer which moves in a + Y direction. (A) is a graph showing the relationship between the displacement of the magnetic flexible layer in the Y-axis direction and the change in the inductance of the coil, and (b) is the shearing force applied to the magnetic flexible layer in the Y-axis direction. It is a graph which shows the relationship with the change of the inductance of the coil.

Hereinafter, embodiments of the present invention will be described in detail.

[Embodiment 1]
FIG. 1A is a cross-sectional view of the tactile sensor 1 according to the first embodiment, FIG. 1B is a bottom view thereof, and FIG. 1C is for explaining the inductance of a coil 5 provided in the tactile sensor 1. It is a figure.

The tactile sensor 1 includes a non-magnetic flexible layer 3 (first flexible layer) formed on the substrate 2 (base material). The magnetic flexible layer 4 (second flexible layer) is formed so as to be supported by the non-magnetic flexible layer 3. Unmagnetized particles having a magnetic permeability higher than that of the non-magnetic flexible layer 3 are dispersed in the magnetic flexible layer 4. However, a non-flexible material having a magnetic permeability lower than that of the magnetic flexible layer 4 may be sandwiched between the substrate 2 and the non-magnetic flexible layer 3, and this non-flexible material may be used as a protective surface for the substrate 2.

A coil 5 whose inductance changes based on the displacement of particles due to an external force acting on the magnetic flexible layer 4 is formed on the substrate 2.

The tactile sensor 1 is provided with an inductance measurement circuit 6 (measurement circuit) that measures a change in the inductance of the coil 5.

The particles dispersed in the magnetic flexible layer 4 include at least one of Fe-based powder, Ni-based powder, and Co-based powder. Here, an example will be described in which the particles are iron powder having a high magnetic permeability and being relatively easily available. The shape of the particles is not particularly limited, and may be spherical, flat, needle-like, columnar, linear, or amorphous.

The coil 5 formed on the substrate 2 is a spiral coil or a spiral coil. FIGS. 1 (a) and 1 (b) show an example of a spiral coil.

The substrate 2 is preferably a flexible substrate, but may be a rigid substrate. Further, the substrate 2 may be a stretchable substrate or a rubber-like substrate. The substrate 2 may have any hardness, thickness, surface texture, shape, and shape as long as it is made of a material having low conductivity. For example, the substrate 2 may be made of wood, fiber, resin, glass, rubber, ceramic, or the like.

The magnetic flexible layer 4 may be any material as long as it contains particles having a magnetic permeability higher than that of the non-magnetic flexible layer 3 and is not magnetized, and is easily deformable. For example, the magnetic flexible layer 4 can be formed of a flexible material such as an elastomer or an elastic foam.

The non-magnetic flexible layer 3 may be any material as long as it can stably support the magnetic flexible layer 4 and is easily deformable. For example, an elastomer or an elastic foam can be used, and any of these can be used. If the non-magnetic flexible layer 3 is configured to be sealed by the magnetic flexible layer 4, the non-magnetic flexible layer 3 may be a gas or liquid, for example, air or water.

The coil 5 may be any coil whose inductance changes due to the approach based on the elastic deformation of the magnetic flexible layer 4. For the coil 5, for example, a coil for general circuit parts such as a chip inductor and a power inductor can be used, and any of these may be used. Further, the coil 5 does not necessarily have to be a spiral coil spirally wound from the substrate 2 toward the magnetic flexible layer 4, and is a flat coil (spiral coil) in which wiring is mounted so as to swirl on the surface of the substrate 2. It may be. Therefore, the coil 5 of the flat coil can be mounted on a thin flexible sheet such as a flexible substrate. The shape of the coil 5 is not particularly limited, and may be any of a circular shape, a quadrangular shape, a triangular shape, and an irregular shape, and a closed circuit having an inductance that operates as the coil 5 may be formed by the coil 5. Further, the diameter, thickness, and number of turns of the coil 5 are not particularly limited.

The tactile sensor 1 converts the magnitude of the external force applied to the magnetic flexible layer 4 or the displacement itself of the magnetic flexible layer 4 due to the external force into an electric signal that can be measured by the inductance measuring circuit 6 connected to the coil 5.

Here, the inductance means a value peculiar to a coil that determines the magnetic flux φ generated when a current I is passed through a certain coil, as shown in the following (Equation 1).

(Magnetic flux φ) = (Inductance L) × (Current I)… (Equation 1),
Therefore, a coil having a large inductance L generates a larger magnetic flux φ.

As shown in FIG. 1 (c), when the coil 5 is a solenoid coil (spiral coil) and a core having a magnetic permeability μ is used for the coil 5 having the number of turns N, the length l, and the cross-sectional area S, the coil is used. The inductance L of 5 is determined by the following (Equation 2).
L = μN ² S / l ... (Equation 2),
Therefore, the inductance L changes according to the magnetic permeability μ of the core of the coil 5.

FIG. 2A is a cross-sectional view showing the operating principle of the tactile sensor 1, FIG. 2B is a diagram showing the appearance of the tactile sensor 1, and FIG. 2C is a substrate 2 and a coil 5 provided on the tactile sensor 1. , Is a perspective view showing a non-magnetic flexible layer 3 and a magnetic flexible layer 4.

When an external force that pushes down the magnetic flexible layer 4 toward the spirally formed coil 5 is applied, the magnetic flexible layer 4 is elastically deformed so as to approach the coil 5, as shown in FIG. 2 (a). Therefore, the positional relationship between the magnetic flexible layer 4 and the coil 5 changes. The inductance value of the coil 5 changes depending on the spatial distribution of the magnetic permeability of the substance around the coil 5. Therefore, when the inductance value of the coil 5 is measured by the inductance measuring circuit 6, it can be detected that an external force is applied to the magnetic flexible layer 4.

Further, if the relationship between the displacement of the magnetic flexible layer 4 generated by the external force applied to the magnetic flexible layer 4 or the inductance value of the coil 5 is understood, the magnitude of the external force applied to the magnetic flexible layer 4 or The displacement of the magnetic flexible layer 4 can be estimated from the inductance value of the coil 5 measured by the inductance measuring circuit 6.

FIG. 3A is a perspective view showing the appearance of a prototype of the tactile sensor 1, FIG. 3B is a plan view showing a substrate 2 provided on the tactile sensor 1, and FIG. 3C is a plan view showing the substrate 2 provided on the substrate 2. It is a plan view of the coil 5, and (d) is a perspective view showing the coil 5 provided on the substrate 2.

The exemplary dimensions of the prototype of the tactile sensor 1 are as follows. The prototype of the tactile sensor 1 has, for example, a substantially rectangular parallelepiped shape having a horizontal dimension of X1 = 150 mm and a vertical dimension of Y1 = 150 mm. On the back surface of the tactile sensor 1, for example, a substrate 2 having a horizontal dimension of X2 = 60 mm and a vertical dimension of Y2 = 60 mm is provided. A spiral coil 5 is formed on the substrate 2. As shown in FIG. 3D, the coil 5 is formed in two layers, for example, on the front surface and the back surface of the substrate 2 having a thickness T = 1.6 mm. As shown in FIG. 3C, the coil 5 is composed of, for example, a diameter D = 20 mm, a number of turns N = 34, a line width W = 0.1 mm, and a line width P = 0.1 mm.

The non-magnetic flexible layer 3 formed on the substrate 2 is made of an elastomer and has dimensions of, for example, 150 mm in length, 150 mm in width, and 10 mm in thickness, and Ecoflex 30 is used as the material.

The magnetic flexible layer 4 formed on the non-magnetic flexible layer 3 is made of an elastomer and has dimensions of, for example, 150 mm in length, 150 mm in width, and 2 mm in thickness, and Ecoflex 30 is used as the material. The magnetic flexible layer 4 has an iron powder content ratio of, for example, a volume ratio of 20%. The contained iron powder has a particle size of, for example, 300 μm. However, it is not limited to these dimensions.

FIG. 4 is a perspective view showing an experimental device of the tactile sensor 1. An experimental device was constructed to measure the inductance of the coil 5 when an external force in the pushing direction was applied to the tactile sensor 1.

This experimental device includes a 3-axis stage 11 on which the tactile sensor 1 is mounted, a plastic cylindrical indenter 7 having a diameter of 10 mm, for example, for applying an external force in the pushing direction to the tactile sensor 1 mounted on the 3-axis stage 11. A 3-axis force torque sensor 8 that measures the external force applied to the tactile sensor 1 by the indenter 7, and an AD converter 9 that AD-converts a signal representing the external force measured by the 3-axis force torque sensor 8 and supplies it to the computer 10. And an inductance measuring circuit 6 for measuring the inductance of the coil 5 provided in the tactile sensor 1.

FIG. 5 is a graph showing the relationship between the pushing depth of the indenter 7 pushed into the tactile sensor 1 and the elapsed time.

The surface of the magnetic flexible layer 4 corresponding to the center of the coil 5 was pressed by an indenter 7 having a diameter of 10 mm. As shown in FIG. 5, the pressing depth was linearly increased from 0 mm to 6 mm for 6 seconds after the start of pressing. Then, the pressing depth of 6 mm was maintained from 6 seconds to 16 seconds. Next, the indentation depth was linearly reduced from 6 mm to 0 mm from 16 seconds to 22 seconds.

FIG. 6 is a graph showing the relationship between the pressing force on the tactile sensor 1 and the inductance of the coil 5. The curve C1 shown in FIG. 6 represents the average value of the inductance of the coil 5 measured when the experiment shown in FIG. 5 was tried 10 times. The region R1 represents a region of the standard deviation 2σ section of the inductance of the coil 5.

As shown in FIG. 6, it was confirmed that the curve C1 showing the inductance with respect to the pressing force increases monotonically, although there is hysteresis. Then, it was confirmed that the noise with respect to the response level of the inductance was very small, and the signal noise ratio (SN ratio) was about 53 dB (the ratio of the signal to the noise was about 1000). It was also confirmed that the region R1 in the standard deviation 2σ section of the inductance of the coil 5 was very narrow compared to the sensor response.

As described above, according to the first embodiment, the magnetic flexible layer 4 formed so as to be supported by the non-magnetic flexible layer 3 is magnetized with a magnetic permeability higher than that of the non-magnetic flexible layer 3. Particles that are not magnetized are dispersed. Therefore, the manufacturing process of arranging the magnetic flexible layer 4 in a strong magnetic field to magnetize the material to be a magnet becomes unnecessary. As a result, it becomes easy to manufacture a tactile sensor having a complicated shape such as a curved surface shape.

Further, since the amount of magnetic flux leaking to the outside of the tactile sensor 1 is small, the tactile sensor 1 can be brought into contact with an object weak to magnetism. Further, the problem that the response of the tactile sensor is changed by the metal that is near the surface of the tactile sensor and is not touched is alleviated.

And since it is not a method of measuring magnetism, it also solves the problem that the tactile sensor itself tilts in the geomagnetism, or the response of the tactile sensor changes when a magnet or electric motor that generates magnetism is nearby. Will be done.

Since the tactile sensor 1 according to the first embodiment has a configuration in which particles are dispersed in the magnetic flexible layer 4, no current flows through the magnetic flexible layer 4 on the surface, and therefore the safety is high.

According to the first embodiment, the magnetic flexible layer 4 and the non-magnetic flexible layer 3 that are distorted by an external force do not have solid objects such as wirings and electric elements. Therefore, even if a large deformation occurs due to an external force, the wiring, the electric element, and the like are not destroyed. Then, only the coil 5 and the wiring connecting the coil 5 to the inductance measurement circuit 6 are arranged on the substrate 2 at the bottom of the tactile sensor 1 to which an external force is applied. Further, the non-magnetic flexible layer 3 is arranged between the coil 5 and the magnetic flexible layer 4 to which an external force is applied. Therefore, the tactile sensor 1 has high durability against an external force.

Further, since the magnetic flexible layer 4 formed on the surface of the tactile sensor 1 is flexible, it has a property of adapting to the shape of the contact target.

Further, since there is no solid substance near the surface of the tactile sensor 1, there is little possibility that the tactile sensor 1 will damage the contact target.

Then, even if the flexible portion including the magnetic flexible layer 4 and the non-magnetic flexible layer 3 is damaged, the flexible portion can be replaced with a new one without making any change to the circuit portion of the substrate 2 including the coil 5. Is. No positioning is required when replacing the flexible part.

The tactile sensor 1 is a method of detecting the deformation of the flexible layer (magnetic flexible layer 4, non-magnetic flexible layer 3) that is deformed by a small external force, and is a method of detecting the deformation of the outermost surface, so that high detection sensitivity is realized. can do.

When the coil 5 is a flat coil (swirl coil), it can be formed by printing conductive ink on a substrate, so that the tactile sensor 1 can be easily mass-produced.

The sensitivity of the tactile sensor 1 can be increased by reducing the thickness of the non-magnetic flexible layer 3 or by reducing the rigidity of the non-magnetic flexible layer 3. By adjusting the material properties of the non-magnetic flexible layer 3 in this way, the sensitivity of the tactile sensor 1 can be adjusted. As a result, the material properties of the non-magnetic flexible layer 3 can be adjusted without increasing the particle content of the magnetic flexible layer 4, adopting the coil 5 having a higher inductance, or passing a stronger current through the coil 5. The sensitivity of the tactile sensor 1 can be adjusted simply by doing so.

The measurement range of the tactile sensor 1 can be widened by increasing the thickness of the non-magnetic flexible layer 3 or increasing the rigidity of the non-magnetic flexible layer 3. By adjusting the material properties of the non-magnetic flexible layer 3 in this way, the measurement width of the tactile sensor 1 can be adjusted.

Further, the non-magnetic flexible layer 3 does not necessarily have to be composed of a single material (layer), and for example, a plurality of layers having different rigidity may be folded in a direction perpendicular to the surface. With such a configuration, it becomes easier to adjust the sensitivity and the measurement width.

The tactile sensor described in Non-Patent Document 1 detects a change in inductance due to compression of the magnetic elastomer by an external force, but in the tactile sensor 1 according to the first embodiment, the magnetic elastomer (magnetic flexible layer 4) is subjected to an external force. The difference is that it detects changes in inductance due to displacement. In Non-Patent Document 1, the particles dispersed in the magnetic elastoma are compressed by an external force, and the change in inductance due to the particles approaching each other and increasing the density is detected. The difference is that the magnetic flexible layer 4) is displaced, and the particles dispersed in the magnetic elastoma are displaced in one direction as a whole to detect a change in inductance due to approaching or moving away from the coil 5. Since the magnetic elastomer of Non-Patent Document 1 is fixed to the frame and the coil is arranged on the opposite side of the magnetic elastomer across the frame, the magnetic elastomer is only compressed and displaced even when an external force is applied. Do not mean. On the other hand, the particles dispersed in the magnetic elastomer (magnetic flexible layer 4) of the tactile sensor 1 according to the first embodiment are displaced by the action of an external force, which changes the inductance of the coil 5, which is non-patented. It is different from the magnetic elastomer of Document 1. As a result, the tactile sensor 1 according to the first embodiment has a large change in the inductance of the coil 5, and can have a higher sensitivity than the tactile sensor of Non-Patent Document 1.

[Embodiment 2]
Other embodiments of the present invention will be described below. For convenience of explanation, the members having the same functions as the members described in the above-described embodiment are designated by the same reference numerals, and the description thereof will not be repeated.

FIG. 7 is a cross-sectional view of the tactile sensor 1A according to the second embodiment. FIG. 8A is a perspective view showing the appearance of the tactile sensor 1A, and FIG. 8B is a substrate 2, coils 5A, 5B, 5C, 5D, non-magnetic flexible layer 3, and magnetic flexibility provided in the tactile sensor 1A. It is a perspective view which shows the layer 4A. FIG. 9 is a plan view schematically showing the relationship between the coils 5A, 5B, 5C, and 5D provided in the tactile sensor 1A and the magnetic flexible layer 4A.

When the magnetic flexible layer (magnetic elastoma, MRE) 4A is spatially locally arranged and the change in inductance of a plurality of coils 5A, 5B, 5C, and 5D is measured, a tactile sensor 1A capable of estimating an external force in a three-dimensional direction is provided. Can be built.

Four coils 5A, 5B, 5C, and 5D arranged in 2 rows and 2 columns are formed on the substrate 2. The magnetic flexible layer 4A is a non-magnetic flexible layer so that a part of the magnetic flexible layer 4A formed in a disk shape overlaps a part of each coil 5A, 5B, 5C, and 5D when viewed from a direction perpendicular to the substrate 2. It is embedded in 3. A plurality of coils may be formed on the substrate 2 so that a part of the magnetic flexible layer 4A overlaps a part of each coil when viewed from a direction perpendicular to the substrate 2. For example, the coils are arranged at the apex positions of a triangle. Three coils may be formed on the substrate 2.

The inductances of the coils 5A, 5B, 5C, and 5D increase or decrease according to the distance between the disk-shaped magnetic flexible layer 4A and the coils 5A, 5B, 5C, and 5D, and from the direction perpendicular to the substrate 2. The amount increases or decreases depending on the degree of overlap between the seen magnetic flexible layer 4A and each coil 5A, 5B, 5C, 5D. Therefore, by measuring each inductance of the coils 5A, 5B, 5C, and 5D with the inductance measuring circuit 6, it is possible to estimate the three-dimensional displacement of the magnetic flexible layer 4A to which the contact force in the three-dimensional direction is applied.

Illustrative dimensions of the coils 5A, 5B, 5C, 5D and the magnetic flexible layer 4A are as follows. Each coil 5A, 5B, 5C, 5D is composed of, for example, a diameter D1 = 10 mm. The distance d1 = 15 mm between the coils 5A and 5D and between the coils 5B and 5C, and the distance d2 = 15 mm between the coils 5A and 5B and between the coils 5C and 5D. The magnetic flexible layer 4A has a diameter of, for example, 16 mm and a thickness of, for example, 3 mm.

FIG. 10A is a graph showing the relationship between the displacement of the magnetic flexible layer 4A in the Z-axis direction and the change in the inductance of the coils 5A, 5B, 5C, and 5D, and FIG. 10B is a graph showing the relationship between the magnetic flexible layer 4A and the magnetic flexible layer 4A. It is a graph which shows the relationship between the vertical force and the change of the inductance of a coil 5A, 5B, 5C, 5D.

When a normal force is applied to the magnetic flexible layer 4A embedded in the non-magnetic flexible layer 3 along the Z direction perpendicular to the substrate 2, the magnetic flexible layer 4A moves in the Z direction. When the magnetic flexible layer 4A moves in the + Z direction, the inductance of all the coils 5A, 5B, 5C, and 5D increases, and when the magnetic flexible layer 4A moves in the -Z direction, all the coils 5A, 5B, 5C, and 5D Inductance is expected to decrease.

As shown in FIGS. 10A and 10B, when the magnetic flexible layer 4A on which a normal force acts along the + Z direction is displaced in the + Z direction, the inductances of all the coils 5A, 5B, 5C, and 5D increase. Was confirmed.

FIG. 11 is a plan view schematically showing the relationship between the coils 5A, 5B, 5C, and 5D provided in the tactile sensor 1A and the magnetic flexible layer 4A moving in the + X direction. FIG. 12A is a graph showing the relationship between the displacement of the magnetic flexible layer 4A in the X-axis direction and the change in the inductance of the coils 5A, 5B, 5C, and 5D, and FIG. 12B is a graph showing the relationship between the magnetic flexible layer 4A and the magnetic flexible layer 4A. It is a graph which shows the relationship between the shearing force in the X-axis direction and the change of the inductance of a coil 5A, 5B, 5C, 5D.

When a shearing force along the X direction parallel to the substrate 2 is applied to the magnetic flexible layer 4A embedded in the non-magnetic flexible layer 3, the magnetic flexible layer 4A moves in the X direction. When the magnetic flexible layer 4A moves in the + X direction, it is expected that the inductance of the coils 5A and 5D will increase and the inductance of the coils 5B and 5C will decrease. Then, when the magnetic flexible layer 4A moves in the −X direction, it is expected that the inductance of the coils 5A and 5D will decrease and the inductance of the coils 5B and 5C will increase.

As shown in FIGS. 12 (a) and 12 (b), the change tendency of the inductance of the coils 5A and 5D coincides with the shearing force along the X direction and the displacement of the magnetic flexible layer 4A along the X direction. It was confirmed that the changing tendencies of the inductances of 5B and 5C match.

FIG. 13 is a plan view schematically showing the relationship between the coils 5A, 5B, 5C, and 5D provided in the tactile sensor 1A and the magnetic flexible layer 4A moving in the + Y direction. FIG. 14A is a graph showing the relationship between the displacement of the magnetic flexible layer 4A in the Y-axis direction and the change in the inductance of the coils 5A, 5B, 5C, and 5D, and FIG. 14B is a graph showing the relationship between the magnetic flexible layer 4A and the magnetic flexible layer 4A. It is a graph which shows the relationship between the shearing force in the Y-axis direction and the change of the inductance of a coil 5A, 5B, 5C, 5D.

When a shearing force along the Y direction parallel to the substrate 2 is applied to the magnetic flexible layer 4A embedded in the non-magnetic flexible layer 3, the magnetic flexible layer 4A moves in the Y direction. When the magnetic flexible layer 4A moves in the + Y direction, it is expected that the inductance of the coils 5A and 5B will increase and the inductance of the coils 5C and 5D will decrease. Then, when the magnetic flexible layer 4A moves in the −Y direction, it is expected that the inductance of the coils 5A and 5B will decrease and the inductance of the coils 5C and 5D will increase.

As shown in FIGS. 14 (a) and 14 (b), the change tendency of the inductance of the coils 5A and 5B coincides with the shearing force along the Y direction and the displacement of the magnetic flexible layer 4A along the Y direction. It was confirmed that the changing tendencies of the inductances of 5C and 5D match.

As described above, according to the second embodiment, the following effects are exhibited in addition to the effects of the first embodiment. That is, the magnetic flexible layer 4A is non-magnetically flexible so that a part of the magnetic flexible layer 4A formed in a disk shape when viewed from the direction perpendicular to the substrate 2 overlaps a part of each coil 5A, 5B, 5C, and 5D. By embedding in the layer 3, it is possible to provide a tactile sensor 1A capable of measuring changes in inductance of a plurality of coils 5A, 5B, 5C, and 5D and estimating an external force in a three-dimensional direction.

The tactile sensors 1.1A according to the first and second embodiments can be applied to, for example, the following applications.

First, as a skin sensor for robots, the hardness and thickness of the flexible layer (magnetic flexible layer 4.4A, non-magnetic flexible layer 3) are effectively adjusted according to the required sensitivity and unexpected force in various parts, and the tactile sensor 1 is effectively used.・ 1A can be used.

For example, in the case of a robot's fingertip, although high sensitivity is required, impact dispersibility is not required, so the flexible layer (magnetic flexible layer 4.4A, non-magnetic flexible layer 3) may be thinned. For the sole of a robot that needs to withstand a large impact or load, the hardness and thickness of the flexible layer (magnetic flexible layer 4.4A, non-magnetic flexible layer 3) may be increased. For the buttocks of a robot that requires high impact dispersibility, the hardness of the flexible layer (magnetic flexible layer 4.4A, non-magnetic flexible layer 3) may be reduced and the thickness may be increased.

Further, by changing the width of the coil 5 in the surface direction (line width P, line width W), the spatial resolution of the tactile sensors 1.1A suitable for each part can be easily realized, and the number of unnecessary sensor channels can be eliminated. be able to. For example, a coil 5 having a narrow width may be used for the fingertips of a robot that requires high spatial resolution, and a coil 5 having a wide width may be used for the back and buttocks of the robot.

Further, when the tactile sensors 1.1A are used on the surface of a robot that a person touches, such as a care robot or a pet robot, the tactile surface can be made safe and sensitive. At the same time, by changing the distribution of hardness and thickness of the flexible layer (magnetic flexible layer 4.4A, non-magnetic flexible layer 3) and arranging fibers and flexible tubes in the flexible layer, the tactile sensor 1.1A It is possible to devise ways to bring the touch feeling closer to the skin of animals.

The tactile sensors 1.1A are also suitable for use as a contact sensor provided at the tip of a medical device that touches the human body or organs, which requires safety and hygiene. For example, during endoscopic or laparoscopic surgery, the tactile sensor 1.1A can be used to measure the hardness of the tissue of the surgical target area and to grasp whether or not an excessive load is applied to the human body during the surgery. It will be possible. In such applications, hygiene can be maintained simply by replacing the surface flexible layer (magnetic flexible layer 4.4A, non-magnetic flexible layer 3) with a new one after use. Since the coil portion and flexible layer of the tactile sensor 1.1A do not have protrusions or large current circuits that may damage the human body, it is safe to press them strongly.

If a toy that can be handled roughly is equipped with a tactile sensor 1.1A, the tactile function will be added to the toy without impairing the soft feel and safety of the toy, and the added value of the toy such as entertainment and educational effects will be increased. Can be done. For example, the stress-relieving effect can be increased by mounting the tactile sensor 1.1A on a ball that has elasticity that relieves stress by gripping it, and producing sound and light according to the strength of the grip. You can expect it. In addition, if the tactile sensor 1.1A is mounted on the soft part of the doll that the child plays, it is possible to add a function that makes the doll say "It hurts" when it is gripped strongly or handled roughly.

By mounting the tactile sensors 1.1A on the contact surface with people who need comfort, such as massage chairs, cockpit seats, and pillows, the comfort is not impaired, and the contact state of people is detected for a more comfortable state. It becomes possible to guide to. For example, by accumulating data by associating the record of the contact state with the evaluation of the comfort of a person, how to make the state comfortable when the state becomes uncomfortable (when moving a little further to the right). A function to advise people on (good, etc.) can be installed in massage chairs and the like.

The tactile sensor 1.1A can be used for the purpose of enhancing the effect by equipping health equipment such as muscle training equipment and facial equipment with a motion adjustment function that takes into account the contact state. For example, a tactile sensor 1.1A is mounted on the contact surface of a device that gives a muscle training effect or a facial beauty effect by vibrating or applying electrical stimulation while being pressed against a part of the body, and is in strong contact with the part. Where not, it is possible to change the amount of vibration and stimulation.

The tactile sensors 1.1A are also suitable as tactile sensors attached to the end effectors of robots that handle food. Since the magnetic flexible layers 4.4A on the surface of the tactile sensor 1.1A are flexible, it does not easily damage soft foods. Since the surface of the tactile sensors 1.1A can be easily cleaned and replaced, hygiene can be ensured. Since the tactile sensor 1.1A can use silicone rubber, which is also used for cooking utensils, as the surface material, it has high safety compatibility.

(summary)
In order to solve the above problems, the tactile sensor according to one aspect of the present invention has a first flexible layer formed on a base material and a magnetic permeability higher than the magnetic permeability of the first flexible layer. The second flexible layer formed so that the unmagnetized particles are dispersed and supported by the first flexible layer, and the particles formed on the base material by an external force acting on the second flexible layer. It is characterized by including one or more coils whose inductance changes based on displacement and a measurement circuit that measures a change in the inductance of the coil.

According to this feature, unmagnetized particles having a magnetic permeability higher than that of the first flexible layer are dispersed in the second flexible layer formed so as to be supported by the first flexible layer. .. Even if the particles are not magnetized, the displacement of the particles causes a change in the inductance of the coil, so that a manufacturing step of arranging a second flexible layer in a strong magnetic field to magnetize the material to be a magnet becomes unnecessary. As a result, it becomes easy to manufacture a tactile sensor having a complicated shape such as a curved surface shape.

Since the amount of magnetic flux leaking out of the tactile sensor is small, the tactile sensor can be brought into contact with an object that is weak against magnetism.

Further, since the sensor for measuring the change in magnetism is not used, the tactile sensor can be used even in an environment where an external magnetic field exists.

In the tactile sensor according to one aspect of the present invention, it is preferable that the particles contain at least one of Fe-based powder, Ni-based powder, and Co-based powder.

According to the above configuration, the inductance of the coil changes due to the displacement of the particles containing at least one of the Fe-based powder, the Ni-based powder, and the Co-based powder.

In the tactile sensor according to one aspect of the present invention, it is preferable that the particles contain iron powder.

According to the above configuration, it can be used as particles having a high magnetic permeability and dispersing particles that are relatively easily available in the second flexible layer.

In the tactile sensor according to one aspect of the present invention, it is preferable that the coil includes at least one of a flat coil and a solenoid coil.

According to the above configuration, the inductances of the planar coil and the solenoid coil change based on the displacement of the particles due to the external force acting on the second flexible layer.

In the tactile sensor according to one aspect of the present invention, it is preferable that the base material is a flexible substrate.

According to the above configuration, the tactile sensor can be mounted on a portion having a complicated shape such as a curved surface shape of a robot.

In the tactile sensor according to one aspect of the present invention, it is preferable that the second flexible layer contains an elastomer or an elastic foam.

According to the above configuration, the second flexible layer can be formed of an elastic material that can be easily deformed.

In the tactile sensor according to one aspect of the present invention, the first coil is arranged so that a part of the second flexible layer overlaps a part of each coil when viewed from a direction perpendicular to the base material. 2 It is preferable that the flexible layer is embedded in the first flexible layer.

According to the above configuration, the external force in the three-dimensional direction can be estimated.

In the tactile sensor according to one aspect of the present invention, the coils are four coils arranged in two rows and two columns, or three coils arranged at the apex positions of a triangle. 2 It is preferable that the flexible layer is formed in a disk shape.

According to the above configuration, the external force in the three-dimensional direction can be estimated with a simple configuration.

In the tactile sensor according to one aspect of the present invention, the displacement of the particles may include the displacement of the particles along the direction perpendicular to the base material and the displacement of the particles along the direction of the surface of the base material. preferable.

According to the above configuration, the displacement of the second flexible layer in the three-dimensional direction can be estimated.

In the tactile sensor according to one aspect of the present invention, it is preferable that the thickness and rigidity of the first flexible layer are set so as to adjust the sensitivity and measurement width of the tactile sensor.

According to the above configuration, the sensitivity and measurement width of the tactile sensor can be adjusted by adjusting the material properties of the first flexible layer.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

1 Tactile sensor 2 Substrate (base material)
3 Non-magnetic flexible layer (first flexible layer)
4 Magnetic flexible layer (second flexible layer)
5 Coil 6 Inductance measurement circuit (measurement circuit)

Claims (9)

The first flexible layer formed on the base material and
A second flexible layer formed so that unmagnetized particles having a magnetic permeability higher than the magnetic permeability of the first flexible layer are dispersed and supported by the first flexible layer,
One or more coils formed on the substrate and whose inductance changes based on the displacement of the particles by an external force acting on the second flexible layer.
It is equipped with a measurement circuit that measures changes in the inductance of the coil.
A plurality of the coils are arranged,
A tactile sensation characterized in that the second flexible layer is embedded in the first flexible layer so that a part of the second flexible layer overlaps a part of each coil when viewed from a direction perpendicular to the base material. Sensor. The tactile sensor according to claim 1, wherein the particles include at least one of Fe-based powder, Ni-based powder, and Co-based powder. The tactile sensor according to claim 2, wherein the particles contain iron powder. The tactile sensor according to claim 1, wherein the coil includes at least one of a flat coil and a solenoid coil. The tactile sensor according to claim 1, wherein the base material is a flexible substrate. The tactile sensor according to claim 1, wherein the second flexible layer contains an elastomer or an elastic foam. The coils are four coils arranged in two rows and two columns, or three coils arranged at the apex positions of a triangle.
The tactile sensor according to claim 1, wherein the second flexible layer is formed in a disk shape. The tactile sensor according to claim 1, wherein the displacement of the particles includes the displacement of the particles along the direction perpendicular to the base material and the displacement of the particles along the direction of the surface of the base material. The tactile sensor according to claim 1, wherein the thickness and rigidity of the first flexible layer are set so as to adjust the sensitivity and measurement width of the tactile sensor.

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