Optical tactile sensor and sensor system

Abstract

This optical tactile sensor (100) comprises: an elastic member (10) having a contact surface (10a) that is brought into contact with an object (2); a holding member (20) having a transparent window part (23), the holding member (20) coming into contact with and holding the elastic member (10); a light source (30); and a camera (40) for imaging the shape of the contact surface (10a) through the window part (23). The elastic member (10) has a first portion having the contact surface (10a), and a transparent second portion formed so as to be integral with the first portion and disposed between the first portion and the window part (23). The second portion has a hardness higher than that of the first portion, and is in contact with the window part (23) across the imaging range of the camera.

Description

Optical tactile sensor and sensor system

[0001] The present disclosure relates to optical tactile sensors and sensor systems.

[0002] Patent Document 1 discloses an optical tactile sensor that can simultaneously measure multiple types of mechanical quantities of force acting on a tactile part from an object when the object comes into contact with the tactile part.

[0003] Japanese Patent Application Laid-Open No. 2005-257343

[0004] However, the technique of Patent Document 1 may result in a decrease in the measurement accuracy of the measured mechanical quantity.

[0005] Therefore, an object of the present disclosure is to provide an optical tactile sensor that can prevent a decrease in measurement accuracy.

[0006] An optical tactile sensor according to one aspect of the present disclosure comprises an elastic member having a contact surface that contacts an object, a holding member having a transparent window that holds the elastic member in contact, a light source, and a camera that photographs the shape of the contact surface through the window, wherein the elastic member has a first portion having the contact surface and a transparent second portion that is formed integrally with the first portion and is positioned between the first portion and the window, and the second portion is harder than the first portion and is in contact with the window throughout the camera's imaging range.

[0007] Furthermore, a sensor system according to one aspect of the present disclosure includes the above-described optical tactile sensor and an information processing device that acquires multiple images obtained by the camera photographing the contact surface at different times, calculates the movement of the contact surface using the multiple images, and calculates at least one of the force that the contact surface is receiving from the object and the change in that force.

[0008] The optical tactile sensor and sensor system of the present disclosure can prevent a decrease in measurement accuracy.

[0009] FIG. 1 is a diagram showing an example of a schematic configuration of a sensor system according to an embodiment. FIG. 2 is a diagram showing an example of a cross-sectional view and two-dimensional pattern of an optical tactile sensor according to an embodiment when no load is applied. FIG. 3 is a diagram showing an example of a cross-sectional view and two-dimensional pattern of an optical tactile sensor according to a comparative example when a load is applied. FIG. 4 is a diagram showing an example of a cross-sectional view and two-dimensional pattern of an optical tactile sensor according to an embodiment when a load is applied. FIG. 5 is a diagram showing images including two-dimensional patterns before and after deformation of the tactile portion. FIG. 6 is a block diagram showing an example of a configuration of an information processing device. FIG. 7 is a diagram showing an example of a cross-sectional view of an optical tactile sensor according to Modification (1). FIG. 8 is a diagram showing an example of a cross-sectional view of an optical tactile sensor according to Modification (2). FIG. 9 is a diagram showing an example of a cross-sectional view of an optical tactile sensor according to Modification (3).

[0010] (Knowledge forming the basis of the present disclosure) Patent Document 1 specifically discloses an optical tactile sensor that includes a tactile part that has a convex curved surface at the tip side that can be in direct contact with an object and is made of a light-transmitting elastic body and has a marker part arranged on the convex curved surface, a pressing member that is transparent and relatively harder than the light-transmitting elastic body and is joined in surface contact with the light-transmitting elastic body, and an imaging means that photographs the behavior of the marker part when an object comes into contact with the convex curved surface from the back side of the tactile part through the pressing member.

[0011] This optical tactile sensor determines mechanical quantities by analyzing images obtained by capturing the behavior of the marker with an imaging device. Therefore, to maintain a certain level of measurement accuracy, it is necessary for the marker to be clearly visible in the image. The marker is captured through a holding member, which is used to prevent deformation of the surface of the tactile device facing the imaging device, making it easier to capture a clear image of the marker.

[0012] However, when the tactile portion is deformed by an external load, it deforms to follow the deformation and may peel off from the pressing member. Even if the tactile portion and the pressing member are firmly bonded with an adhesive to prevent peeling due to deformation, the tactile portion itself may tear because it is an elastic and relatively fragile body. Thus, with conventional technology, peeling between the tactile portion and the pressing member or damage to the tactile portion itself may make it difficult to obtain a good image of the marker portion. This may result in a decrease in the measurement accuracy of the measured mechanical quantity.

[0013] Therefore, after extensive research, the present inventors have discovered an optical tactile sensor that can prevent a decrease in measurement accuracy.

[0014] An optical tactile sensor according to one aspect of the present disclosure comprises an elastic member having a contact surface that contacts an object, a holding member having a transparent window that holds the elastic member in contact, a light source, and a camera that photographs the shape of the contact surface through the window, wherein the elastic member has a first portion having the contact surface and a transparent second portion that is formed integrally with the first portion and is positioned between the first portion and the window, and the second portion is harder than the first portion and is in contact with the window throughout the camera's imaging range.

[0015] According to this, the second portion of the elastic member is harder than the first portion having the contact surface and is in contact with the window portion over the entire imaging range of the camera. In other words, the portion of the elastic member that is in contact with the window portion over the entire imaging range of the camera is less likely to deform than the first portion. Therefore, even if an external load is applied to the contact surface and the first portion deforms, the second portion is less likely to deform. This allows the camera to capture an image that clearly captures the contact surface through the window portion. Therefore, it is possible to prevent a decrease in the measurement accuracy of the measured mechanical quantity.

[0016] The elastic member may be formed so that its hardness gradually increases from the first portion toward the second portion.

[0017] Therefore, when an external load is applied to the contact surface and the first portion is deformed, the amount of deformation can be made smaller toward the second portion, making it possible to make the second portion less susceptible to deformation.

[0018] The elastic member may be formed so that its hardness increases stepwise from the first portion to the second portion.

[0019] Therefore, when an external load is applied to the contact surface and the first portion is deformed, the amount of deformation can be gradually reduced toward the second portion, making the second portion less susceptible to deformation.

[0020] The elastic member may be formed so that its hardness varies in three or more stages.

[0021] Therefore, when an external load is applied to the contact surface and the first portion is deformed, the amount of deformation can be gradually reduced in three or more stages toward the second portion, making it possible to make the second portion less susceptible to deformation.

[0022] Furthermore, the elastic member may have a first surface and a second surface that are different from each other and adjacent to each other, the retaining member may have a first member that contacts the first surface and a second member that contacts the second surface, the first member may have the window portion, and the second portion may have the first surface and the second surface.

[0023] In this case, the second portion has not only the first surface but also the second surface, and is formed so as to cover not only the first surface side of the first portion but also the second surface side, which makes it possible to make the second portion less susceptible to deformation.

[0024] Furthermore, a portion of the second portion having the second surface may have a thickness that decreases with increasing distance from the first surface.

[0025] Therefore, the volume of the first portion can be increased relative to the second portion as it moves away from the first surface. This makes it easier to deform the contact surface of the elastic member, and minimizes a decrease in measurement sensitivity. In other words, by forming the second portion to cover the second surface side of the first portion, it is possible to make the second portion less susceptible to deformation and improve measurement sensitivity at the same time.

[0026] Furthermore, the contact surface and the first surface may be adjacent to each other, the contact surface and the second surface may be opposite each other, and the angle formed by the first member on which the elastic member is arranged and the second member may be greater than or equal to 90 degrees and less than or equal to 135 degrees.

[0027] In this case, since the contact surface and the first surface are adjacent to each other, the camera is disposed, for example, on the first surface side of the elastic member. In this way, the camera is not disposed on the opposite side of the elastic member from the contact surface, but is disposed to the side of the elastic member when the elastic member is viewed from the normal direction of the contact surface, which makes it possible to reduce the thickness of the optical tactile sensor in the normal direction to the contact surface.

[0028] The Shore A hardness of the elastic member other than the second portion may be 10° or more and 30° or less, and the Shore A hardness of the second portion may be 10° or more higher than that of the other portion.

[0029] This makes it possible to realize the other portions excluding the second portion for improving measurement sensitivity and the second portion for improving measurement accuracy.

[0030] The Shore A hardness of the second portion may be 20° or more higher than that of the other portion.

[0031] This makes it possible to realize a second portion that is less likely to deform, thereby improving measurement accuracy.

[0032] Furthermore, the ratio of the thickness of the second portion to the thickness of the other portion of the elastic member excluding the second portion on a straight line connecting the center of the contact surface and the center of the window portion may be 2 or more and 9 or less.

[0033] This makes it possible to realize the other portions excluding the second portion for improving measurement sensitivity and the second portion for improving measurement accuracy.

[0034] The holding member may be entirely made of a transparent material.

[0035] Therefore, the holding member can be made of one type of material, which can be easily realized.

[0036] The holding member may have an opening, and the window portion may be a transparent plate-like member that closes the opening.

[0037] A sensor system according to one aspect of the present disclosure includes the optical tactile sensor described above, and an information processing device that acquires multiple images obtained by the camera photographing the contact surface at different times, calculates the movement of the contact surface using the multiple images, and calculates at least one of the force that the contact surface is receiving from the object and the change in that force.

[0038] This makes it possible to identify the shape of an object pressed against the contact surface and estimate what the object is.

[0039] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not described in the independent claims are described as optional components.

[0040] In addition, each drawing is a schematic diagram and is not necessarily an exact illustration. In addition, the same components are denoted by the same reference numerals in each drawing.

[0041] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0042] (Embodiment) [1. Configuration] FIG. 1 is a diagram showing an example of a schematic configuration of a sensor system according to an embodiment.

[0043] The sensor system 1 includes an optical tactile sensor 100 and an information processing device 200. In Fig. 1, the side of the optical tactile sensor 100 on which the contact surface 10a is located is referred to as the front side, and the opposite side is referred to as the rear side.

[0044] When an object comes into contact with the contact surface 10a on the front side of the elastic member 10, the optical tactile sensor 100 photographs the shape of the deformed contact surface 10a with a camera 40 located on the rear side of the elastic member 10 while light from a light source 30 is irradiated from the rear side. This produces image data 50 that indicates an image for detecting the magnitude and direction of the force acting on the contact surface 10a from the object. The information processing device 200 performs a predetermined image analysis on the image data 50 obtained by the optical tactile sensor 100 to calculate the magnitude and direction of the force acting on the contact surface 10a from the object.

[0045] [1-1. Optical Tactile Sensor] The specific configuration of the optical tactile sensor 100 will be described with reference to FIGS.

[0046] 2A and 2B are diagrams showing a cross-sectional view of the optical tactile sensor according to the embodiment when no load is applied and an example of a two-dimensional pattern. Fig. 2A is a cross-sectional view of the optical tactile sensor 100 cut along a plane passing through the optical axis L1 of the camera 40. Fig. 2B is a diagram showing the two-dimensional pattern 15 as seen through the window 23 of the holding member 20 in the state of Fig. 2A (i.e., when no load is applied by an object).

[0047] The optical tactile sensor 100 includes an elastic member 10 , a holding member 20 , a light source 30 , and a camera 40 .

[0048] The elastic member 10 has a contact surface 10a that comes into contact with the object 2. The contact surface 10a is, for example, an outwardly convex curved surface. The curved surface may be a part of a sphere, a part of an ellipsoid or a paraboloid, or a part of the side surface of a cylinder. The curved surface is not limited to a curved surface with a constant curvature, as long as it is an outwardly convex curved surface. The elastic member 10 has a transparent portion behind the first layer 11a, which includes the contact surface 10a. Therefore, when the elastic member 10 is viewed from behind, the first layer 11a can be seen. Furthermore, the portion of the elastic member 10 that includes the contact surface 10a is made of an elastic material.

[0049] [1-1-1. Elastic Member] Specifically, the elastic member 10 has a top layer 11, a first intermediate layer 12, a second intermediate layer 13, and a bottom layer 14. The top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 each have a flat plate-like shape and are stacked in the front-to-back direction. The elastic member 10 is an elastic body. As shown in FIG. 2(a), the cross-sectional shape of the elastic member 10 is a substantially isosceles trapezoid whose rear base is shorter than its front base. The elastic member 10 has a front contact surface 10a, a rear surface 10b, and a lateral surface 10c. The contact surface 10a and the lateral surface 10c are different surfaces of the elastic member 10 and adjacent to each other. The rear surface 10b and the lateral surface 10c are different surfaces of the elastic member 10 and adjacent to each other. The contact surface 10a and the rear surface 10b are different surfaces of the elastic member 10 and are opposed to each other in the front-to-rear direction. In the present embodiment, the rear surface 10b is an example of a first surface, and the side surface 10c is an example of a second surface.

[0050] The top layer 11 has a contact surface 10a. The top layer 11 has a first layer 11a that is a part of the top layer 11. The first layer 11a is an elastic body that has the contact surface 10a. The top layer 11 is an example of a first part of the elastic member 10.

[0051] The first layer 11a has a contact surface 10a on the front side. The thickness of the first layer 11a is substantially constant at any position. The first layer 11a may be a scatterer. Alternatively, the first layer 11a may be made of an opaque material. Alternatively, the first layer 11a may be made of a scatterer and an opaque material. The first layer 11a may be made of a material colored to reflect light. The color may be white, a color other than white, such as red, blue, yellow, or green, or a color formed by mixing two or more of these colors. Alternatively, the first layer 11a may be made of a material having light-blocking properties or a material colored to have light-blocking properties. The first layer 11a may be made of, for example, a silicone resin, a urethane resin, or the like.

[0052] The first layer 11a may be configured to have light-blocking properties by, for example, incorporating light-reflecting particles (e.g., silver paste) into a base material such as silicone resin or urethane resin, so that the particles are arranged two-dimensionally with no gaps. The first layer 11a may also be configured to have light-blocking properties by, for example, incorporating light-absorbing particles (e.g., carbon particles (graphene)) into a base material such as silicone resin or urethane resin, so that the particles are arranged two-dimensionally with no gaps. The latter first layer 11a may have a two-layer structure further including a layer containing light-scattering particles (titanium oxide).

[0053] The second layer 11b is a transparent elastic body that contacts the rear surface of the first layer 11a. When viewed from the front, the center portion of the second layer 11b is thicker than the surrounding portions. Specifically, the front surface of the front side (first layer 11a side) of the second layer 11b is raised so that the center portion protrudes forward more than the surrounding portions, and the rear surface of the rear side of the second layer 11b is flat. The second layer 11b is made of, for example, silicone resin, urethane resin, etc.

[0054] The first layer 11a may have the same hardness as the second layer 11b, or may have a hardness higher than that of the second layer 11b. When the hardnesses of the first layer 11a and the second layer 11b are different, the hardness of the top layer 11 is represented by the hardness of the second layer 11b. This is because the volume of the second layer 11b is larger than the volume of the first layer 11a, and the first layer 11a is a thin layer, so the hardness of the second layer 11b is more dominant.

[0055] The first intermediate layer 12 is a transparent elastic body that contacts the rear of the top layer 11. The first intermediate layer 12 is formed to have a higher hardness than the top layer 11. Note that when the first layer 11a and the second layer 11b that form the top layer 11 have different hardnesses, the first intermediate layer 12 is formed to have a higher hardness than the hardness of the second layer 11b, which is typified by the hardness of the top layer 11. The first intermediate layer 12 is made of, for example, a silicone resin, a urethane resin, or the like.

[0056] The second intermediate layer 13 is a transparent elastic body that contacts the rear of the first intermediate layer 12. The second intermediate layer 13 is formed to have a higher hardness than the first intermediate layer 12. The second intermediate layer 13 is made of, for example, a silicone resin, a urethane resin, or the like.

[0057] The bottom layer 14 is a transparent elastic body that contacts the rear of the second intermediate layer 13. The bottom layer 14 is formed to have a higher hardness than the second intermediate layer 13. The rear surface of the bottom layer 14 contacts the entire front surface of a window portion 23 (described later) of the holding member 20. Note that the bottom layer 14 only needs to contact the entire shooting range of the camera 40 in the window portion 23, and does not have to contact the entire front surface of the window portion 23. The shooting range of the camera 40 is a partial area of ​​the front surface of the window portion 23. The bottom layer 14 is made of, for example, silicone resin, urethane resin, etc. Note that the bottom layer 14 is an example of the second portion of the elastic member 10.

[0058] In this way, the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 have different hardnesses, with the top layer 11 having the lowest hardness and the hardness increasing in the order of the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14. Furthermore, the second layer 11b of the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 are each made of a transparent material.

[0059] In other words, the elastic member 10 is formed so that the hardness increases stepwise from the top layer 11 to the bottom layer 14. The elastic member 10 is formed so that the hardness changes in four steps: the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14. Note that the elastic member 10 may be formed so that the hardness changes in three or more steps, as in this embodiment, or so that the hardness changes in two steps.

[0060] For example, the Shore A hardness of the portions of the elastic member 10 other than the bottom layer 14 (i.e., the top layer 11, the first intermediate layer 12, and the second intermediate layer 13) may be 10° or greater and 30° or less. The Shore A hardness of the bottom layer 14 may be 10° or greater than the Shore A hardness of the top layer 11, more preferably 20° or greater than the Shore A hardness of the top layer 11. Furthermore, the Shore A hardness of the portions of the elastic member 10 other than the bottom layer 14 (i.e., the top layer 11, the first intermediate layer 12, and the second intermediate layer 13) may be 30° or greater and 50° or less. The Shore A hardness of the bottom layer 14 may be 5° or greater than the Shore A hardness of the top layer 11, more preferably 10° or greater than the Shore A hardness of the top layer 11.

[0061] The Shore A hardness of the first intermediate layer 12 must be higher than the Shore A hardness of the top layer 11 and lower than the Shore A hardness of the second intermediate layer 13, and the Shore A hardness of the second intermediate layer 13 must be higher than the Shore A hardness of the first intermediate layer 12 and lower than the Shore A hardness of the bottom layer 14.

[0062] The top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 are made of the same material. For example, the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 are made of either a silicone resin or a urethane resin.

[0063] The hardness of the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 may be adjusted by adjusting the amount of curing agent mixed per unit volume. Specifically, the greater the amount of curing agent, the higher the hardness achieved. In other words, the hardness may be adjusted so that the bottom layer 14 has the highest hardness by mixing the smallest amount of curing agent in the top layer 11 and increasing the amount of additive mixed in the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14, in that order.

[0064] The hardness of the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 may be adjusted by adjusting the heating time when curing the uncured resin material. Specifically, the longer the heating time, the higher the hardness achieved. In other words, the hardness of the bottom layer 14 may be adjusted to be highest by setting the heating time for mixing the top layer 11 to be the shortest and then increasing the heating times for the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 in that order.

[0065] Here, we will explain the case where silicone resin is used for at least one of the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14. When silicone resin is used as the material, the base agent and the curing agent are mixed in a 1:1 ratio. During mixing, the mixture is stirred with a stirrer in a space reduced in pressure or evacuated by a vacuum unit to degas the air in the mixed solution. The degassed mixed solution is then heated, for example, at 150°C for about 30 minutes to harden the mixed solution. In this way, a cured silicone resin can be obtained. For example, the mixed solution before the silicone resin hardens can be placed in molds shaped like the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14, thereby obtaining the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 made of silicone resin.

[0066] Furthermore, the hardness of the silicone resin can be adjusted by adjusting the heating temperature and heating time during heating after degassing. For example, if the mixed solution is cured by maintaining it at a temperature of 23°C for 24 hours, a silicone resin having a Shore A hardness of 28° is obtained. Furthermore, if the mixed solution is cured by heating it at a temperature of 100°C for 3 hours, a silicone resin having a Shore A hardness of 55° is obtained. In this way, a silicone resin adjusted to the desired hardness is obtained.

[0067] Next, we will explain the case where urethane resin is used for at least one of the top layer 11, first intermediate layer 12, second intermediate layer 13, and bottom layer 14. When using urethane resin as the material, the base agent and curing agent are mixed in a ratio of 100:14 to 17. During mixing, the mixture is stirred with a stirrer in a space reduced in pressure or evacuated by a vacuum unit to degas the air in the mixed solution. The degassed mixed solution is then heated, for example, at 100°C for approximately 60 minutes to harden the mixed solution. In this way, a hardened urethane resin can be obtained. For example, the mixed solution before hardening of the urethane resin can be placed in molds shaped like the top layer 11, first intermediate layer 12, second intermediate layer 13, and bottom layer 14, thereby obtaining the top layer 11, first intermediate layer 12, second intermediate layer 13, and bottom layer 14 made of urethane resin.

[0068] The top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 may be formed by stacking and curing the bottom layer 14, the second intermediate layer 13, the first intermediate layer 12, and the top layer 11 in that order. That is, after the bottom layer 14 is cured in a mold for forming the elastic member 10, a mixed solution for forming the second intermediate layer 13 is poured above the cured bottom layer 14 and cured. Then, a mixed solution for forming the first intermediate layer 12 is poured above the cured second intermediate layer 13 and cured. Then, a mixed solution for forming the top layer 11 is poured above the cured first intermediate layer 12 and cured. In this manner, an elastic member 10 may be manufactured in which the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 are bonded together.

[0069] The boundaries between the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 may be bonded with an adhesive. The top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 may be bonded together by sandwiching the same type of material as the two adjacent layers between the boundaries and heating and curing the material. The material sandwiched between the boundaries between the two adjacent layers may be applied to the surface of one layer that contacts the other layer, or may be applied to the surface of the other layer that contacts the one layer. In this way, an elastic member 10 may be manufactured in which the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 are tightly bonded together.

[0070] Furthermore, the ratio of the thicknesses of the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 of the elastic member 10 in the front-to-rear direction may be defined as follows: The ratio of the total thickness TH1 of the portions of the elastic member 10 other than the bottom layer 14 (i.e., the top layer 11, the first intermediate layer 12, and the second intermediate layer 13) to the thickness TH2 of the bottom layer 14 on the straight line connecting the center of the contact surface 10a and the center of the window portion 23 may be 2 or greater and 9 or less.

[0071] The top layer 11 also has a two-dimensional pattern 15 arranged along the contact surface 10a, as shown in FIG. 2(b).

[0072] The two-dimensional pattern 15 may be disposed, for example, on the rear surface of the first layer 11 a. That is, the two-dimensional pattern 15 is disposed between the first layer 11 a and the second layer 11 b. It can also be said that the two-dimensional pattern 15 is disposed on the front surface of the second layer 11 b.

[0073] The two-dimensional pattern 15 may be a pattern (design) made up of a plurality of dots 15a arranged two-dimensionally, as shown in Fig. 2(b). The two-dimensional pattern 15 may also be a pattern (design) made up of grid lines, which are a group of straight lines extending in two different directions and intersecting each other. The two-dimensional pattern 15 may also be a pattern (design) other than a plurality of dots 15a and grid lines, as long as it is a pattern (design) arranged two-dimensionally.

[0074] The two-dimensional pattern 15 may be a pattern (design) that is regularly arranged two-dimensionally, which can simplify image processing and reduce the processing load required for image processing.

[0075] The two-dimensional pattern 15 may have a color different from that of the first layer 11a, for example, black. The two-dimensional pattern 15 is not limited to black as long as it has a color different from that of the first layer 11a. The pattern (design) consisting of multiple dots may be recessed or protruding portions formed in the first layer 11a. The pattern (design) consisting of grid lines may be grooves or protruding portions (ribs) formed in the first layer 11a. The two-dimensional pattern 15 may have any configuration as long as it can be distinguished from portions of the first layer 11a where the two-dimensional pattern 15 is not arranged in an image captured by the camera 40.

[0076] The two-dimensional pattern 15 may be formed, for example, by screen-printing a black-colored base material on the rear surface of the first layer 11 a. Alternatively, the two-dimensional pattern 15 may be formed by screen-printing a black-colored base material on the front surface of the second layer 11 b.

[0077] The two-dimensional pattern 15 may be disposed inside the first layer 11a, that is, between the contact surface 10a and the rear surface of the first layer 11a, or may be disposed on the contact surface 10a. When the two-dimensional pattern 15 is disposed on the contact surface 10a, the first layer 11a may be transparent so that the two-dimensional pattern 15 is included in an image captured by the camera 40, that is, so that the two-dimensional pattern 15 is distinguishable in the image.

[0078] [1-1-2. Holding Member] The holding member 20 has a bottom member 21 that contacts the rear surface 10b of the elastic member 10, and a side member 22 that contacts the side surface 10c of the elastic member 10. The bottom member 21 is a portion that supports the elastic member 10 from behind, and is an example of a first member. The bottom member 21 has an opening 24 formed in the center, and has a window portion 23 that is arranged to cover the opening 24. The window portion 23 is a transparent plate-like member. The side member 22 is a portion that supports the elastic member 10 from the side, and is an example of a second member. The side member 22 is arranged to extend forward from the periphery of the bottom member 21, and is arranged to surround the sides of the elastic member 10.

[0079] The holding member 20 has higher rigidity than the elastic member 10. The holding member 20 has a hardness that makes it less likely to bend when, for example, the contact surface 10a is pressed by the object 2. The Shore A hardness of the holding member 20 may be, for example, 90 or higher. The rigidity of the holding member 20 may be such that the deflection of the holding member 20 caused by the contact surface 10a being deformed by a force of the magnitude expected to be applied by the object 2 is sufficiently smaller than the amount of depression of the elastic member 10 when the contact surface 10a is pressed. Here, "sufficiently small" means, for example, 1 / 50 or less. The holding member 20 and the elastic member 10 are fixed in close contact with each other. A transparent adhesive may be applied between the holding member 20 and the elastic member 10 to more firmly fix the holding member 20 and the elastic member 10. Note that the bottom member 21 need only be transparent and capable of holding the elastic member 10, and does not need to have a uniform thickness. The holding member 20 is made of, for example, polycarbonate, glass, acrylic resin, cycloolefin resin, etc. Note that the holding member 20 only needs to be transparent at least in the portion of the side member 22 where light is irradiated by the light source 30 and in the window portion 23, and other portions may be opaque.

[0080] [1-1-3. Light Source] The light source 30 is disposed to the side of the elastic member 10 and emits light diagonally forward from the side of the elastic member 10. In other words, the light source 30 emits light toward the first layer 11a via the holding member 20 and at least the second layer 11b of the second layer 11b, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14.

[0081] The light source 30 may be disposed behind the elastic member 10. In this case, the light source 30 may be disposed to the side of the camera 40 when viewed along the optical axis of the camera 40. The light source 30 may be disposed at any position as long as it is disposed outside the angle of view (i.e., the shooting range) of the camera 40 and can emit light from behind the first layer 11a.

[0082] The light source 30 is, for example, a light emitting diode (LED). Note that the light source 30 is not limited to an LED, and may be a light bulb, a fluorescent lamp, an organic electroluminescence (EL) light, or the like.

[0083] Light source 30 may be a light source that emits light of a specific color such as red, green, or blue, or may be a light source that emits light that is a mixture of multiple lights with wavelengths corresponding to multiple colors. Note that light source 30 may be any light source that emits light that can be detected by the image sensor of camera 40.

[0084] [1-1-4. Camera] The camera 40 is disposed on the side opposite to the contact surface 10a of the elastic member 10 (i.e., the rear side of the elastic member 10) in a position facing the elastic member 10. The positional relationship between the camera 40 and the elastic member 10 may be fixed. That is, the distance between the camera 40 and the elastic member 10 may be fixed. For example, the camera 40 and the elastic member 10 may be fixed by a support member (not shown). The camera 40 may be disposed so that its optical axis passes through the center of the elastic member 10 and is perpendicular to the holding member 20 of the elastic member 10. Note that the camera 40 may be disposed in any position and in any position as long as it is disposed in a position that allows it to capture an image of the entire first layer 11a (or the two-dimensional pattern 15) of the elastic member 10 from behind.

[0085] The camera 40 captures an image of the first layer 11a (or the two-dimensional pattern 15) of the elastic member 10 that has received light from the light source 30. The camera 40 may, for example, sequentially capture images of the first layer 11a (or the two-dimensional pattern 15). That is, the camera 40 is not limited to capturing one still image, but may also capture multiple still images or a moving image. Therefore, the image captured by the camera 40 may be multiple still images or a moving image.

[0086] The camera 40 is, for example, a charge coupled device (CCD) camera, a complementary metal oxide semiconductor (CMOS) camera, etc. The camera 40 may be a color camera or a monochrome camera.

[0087] Because the holding member 20, the second layer 11b, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 are made of transparent materials, light emitted by the light source 30 reaches the first layer 11a. The light that reaches the first layer 11a is reflected (scattered) by the rear surface of the first layer 11a or inside the first layer 11a, passes through the second layer 11b, the first intermediate layer 12, the second intermediate layer 13, the bottom layer 14, and the holding member 20, travels backward, and is received by the camera 40. In this way, the camera 40 captures an image of the first layer 11a including the two-dimensional pattern 15.

[0088] 3 is a diagram showing a cross-sectional view and an example of a two-dimensional pattern of an optical tactile sensor according to a comparative example when a load is applied. The comparative example is an example of an optical tactile sensor that employs an elastic member 110 made of a material with a uniform hardness. The optical tactile sensor of the comparative example has the same configuration as the optical tactile sensor 100 according to the embodiment, except that the elastic member 110 is made of a uniform hardness. Therefore, the same components are designated by the same reference numerals and their descriptions are omitted.

[0089] Fig. 3(a) is a cross-sectional view of the optical tactile sensor of the comparative example when a load is applied, taken along a plane passing through the optical axis of the camera 40. Fig. 3(b) is a diagram showing the two-dimensional pattern 15 as seen through the window 23 of the holding member 20 in the state of Fig. 3(a) (i.e., when a load is applied by the object 2).

[0090] As shown in FIG. 3A , when a load is applied from the object 2 to the contact surface 110a of the elastic member 110, the contact surface 110a is pushed by the object 2 and deforms to follow the shape of the object 2. Furthermore, when the contact surface 110a of the elastic member 110 deforms, the surfaces of the elastic member 110 other than the contact surface 110a deform in response to the deformation of the contact surface 110a. For example, a boundary portion A1 between the bottom surface 110b and the side surface 110c of the elastic member 110 and a boundary portion A2 between the contact surface 110a and the side surface 110c of the elastic member 110 may deform into a curved shape, which may cause the elastic member 110 to peel off from the holding member 20. In particular, if the boundary portion A1 between the bottom surface 110b and the side surface 110c of the elastic member 110 deforms and the elastic member 110 peels off from the window portion 23 of the holding member 20, an air layer will be trapped between the elastic member 110 and the window portion 23. 3B, the two-dimensional pattern 15 at the boundary portion A1 appears blurred compared to the portion A3 where the elastic member 110 is in contact with the window portion 23. Therefore, it is difficult to obtain an image in which the two-dimensional pattern 15 is clearly captured.

[0091] 4A and 4B are diagrams showing a cross-sectional view and an example of a two-dimensional pattern of the optical tactile sensor according to the embodiment when a load is applied. Fig. 4A is a cross-sectional view of the optical tactile sensor 100 when a load is applied, taken along a plane passing through the optical axis of the camera 40. Fig. 4B is a diagram showing the two-dimensional pattern 15 as viewed through the window 23 of the holding member 20 in the state of Fig. 4A (i.e., when a load is applied by an object).

[0092] As shown in Figure 4(a) , when a load is applied from the object 2 to the contact surface 10a of the elastic member 10, the contact surface 10a is pushed by the object 2 and deforms to follow the shape of the object 2. However, because the hardness of the bottom layer 14 of the elastic member 10 is configured to be higher than the hardness of the top layer 11, even if the contact surface 10a deforms, the portion A31 of the rear surface 10b that is in contact with the window portion 23 is less likely to deform. This allows the elastic member 10 and the window portion 23 to maintain contact, as shown in Figure 4(b) , making it possible to obtain an image in which the two-dimensional pattern 15 is clearly captured.

[0093] 5 is a diagram showing an image including a two-dimensional pattern before and after deformation of the tactile section. In order to clearly explain the displacement of the plurality of dots 15a that make up the two-dimensional pattern 15, Fig. 5 shows the plurality of dots 15a whose outer edges are indicated by solid circles and the centers 15b of the plurality of dots 15a.

[0094] When the camera 40 captures an image when the contact surface 10a of the elastic member 10 is not subjected to force from the object 2 and is not deformed, an image 51 shown in Fig. 5(a) is obtained. The image 51 shows the two-dimensional pattern 15 that is not deformed.

[0095] When the camera 40 captures an image while the contact surface 10a of the elastic member 10 is being deformed by the force from the object 2, an image 52 shown in Fig. 5B, for example, is obtained. The image 52 shows a plurality of dots 16a that are displacements of the plurality of dots 15a in the undeformed two-dimensional pattern 15. It can be seen that the centers 16b of the plurality of dots 16a have moved to a position displaced from the center 15b of the plurality of dots 15a.

[0096] The first layer 11a is an elastic body having a uniform thickness and being sufficiently thinner than the second layer 11b, and therefore deforms to a shape corresponding to the deformation of the contact surface 10a. Therefore, an image 52 of the first layer 11a deforming to a shape corresponding to the deformation of the contact surface 10a is obtained. In other words, it can be said that the image 52 includes the shape of the contact surface 10a. When the first layer 11a is deformed, the two-dimensional pattern 15 disposed on the rear surface of the first layer 11a also deforms in response to the deformation. Therefore, the image 52 obtained when the contact surface 10a is deformed by the force from the object 2 includes a deformed two-dimensional pattern 15, as shown in FIG. 5B . In the deformed two-dimensional pattern 15, multiple dots are displaced, i.e., the positions of multiple dots are shifted, compared to the undeformed two-dimensional pattern 15.

[0097] 5 illustrates a two-dimensional pattern 15 composed of a plurality of dots. However, in the case of a two-dimensional pattern composed of grid lines, the grid lines are deformed in response to deformation of the contact surface 10a. For example, the positions of the intersections of the grid lines are shifted compared to when the contact surface 10a is not deformed. Furthermore, the straight grid lines are deformed into curved lines.

[0098] Image data 50 including images 51 and 52 obtained by the camera 40 is output to the information processing device 200 .

[0099] [1-2. Information Processing Device] FIG. 6 is a block diagram showing an example of the configuration of an information processing device.

[0100] 6 , the information processing device 200 includes, as its hardware configuration, a processor 201, a main memory 202, a storage 203, and a communication IF (Interface) 204. The information processing device 200 may further include an input IF (Interface) 205 and a display 206.

[0101] The processor 201 is a processor that executes a program stored in the storage 203 or the like.

[0102] The main memory 202 is a volatile storage area that is used to temporarily store data generated during processing by the processor 201, used as a work area used when the processor 201 executes a program, and used to temporarily store data received by the communication IF 204.

[0103] The storage 203 is a non-volatile storage area that holds various data such as programs. The storage 203 stores data including, for example, various data generated as a result of processing by the processor 201 and image data 50 received via the communication IF 204. The storage 203 may also store in advance image data representing an image 51 captured when the contact surface 10a of the elastic member 10 is not subjected to force from the object 2 and is not deformed. The storage 203 may also store feature information representing features of the two-dimensional pattern 15 included in the image 51. The feature information may be, for example, information (two-dimensional coordinates) representing the positions on the image 51 of the plurality of dots 15a that make up the two-dimensional pattern 15.

[0104] The communication IF 204 is a communication interface for receiving image data 50 from the camera 40. The communication IF 204 may also be a communication interface for transmitting data to and from an external device such as a smartphone, a tablet, a PC (Personal Computer), or a server. The communication IF 204 may be an interface for wireless communication, such as a wireless LAN interface or a Bluetooth (registered trademark) interface. The communication IF 204 may also be an interface for wired communication, such as a USB (Universal Serial Bus) or a wired LAN interface.

[0105] The input IF 205 is an interface for receiving input from a person, and may be a pointing device such as a mouse, a touchpad, a touch panel, or a trackball, or may be a keyboard.

[0106] The display 206 is a liquid crystal display, an organic EL display, or the like.

[0107] The information processing device 200 realizes the following functions by the processor 201 executing a program.

[0108] The information processing device 200 acquires image data 50 output from the camera 40 and performs a predetermined image analysis on images 51 and 52 included in the acquired image data 50. The information processing device 200 recognizes the shape of the two-dimensional pattern 15 included in each of the images 51 and 52, and calculates the magnitude and direction of the force applied to the contact surface 10a from the object 2 based on the shape of the recognized two-dimensional pattern 15. The information processing device 200 compares the image 51 stored in the storage 203 with each of the acquired images 51 and 52, and calculates the magnitude and direction of the force based on the comparison result. For example, the information processing device 200 compares the two-dimensional coordinates of the multiple dots 15a in the two-dimensional pattern 15 included in the image 51 stored in the storage 203 with the two-dimensional coordinates of the multiple dots 15a and 16a in the two-dimensional pattern 15 included in the acquired images 51 and 52.

[0109] When the acquired image is image 51, the information processing device 200 may determine that no force is being applied from the object 2 because there is no difference between the two-dimensional coordinates of the multiple dots 15a in the two-dimensional patterns 15 of both images. When the acquired image is image 52, the information processing device 200 determines that a difference exists between the two-dimensional coordinates of the multiple dots 15a in the two-dimensional pattern 15 included in image 51 stored in storage 203 and the two-dimensional coordinates of the multiple dots 16a in the two-dimensional pattern 15 included in acquired image 52. The information processing device 200 identifies this difference and, based on the identified difference, calculates the magnitude and direction of the force that the contact surface 10a is receiving from the object 2. That is, the information processing device 200 vectorizes the load that the contact surface 10a is receiving from the object 2.

[0110] In addition, the information processing device 200 may calculate the movement of the contact surface 10a using multiple images 51, 52 included in the image data 50, and calculate at least one of the force that the contact surface 10a is receiving from the object 2 and the change in that force.

[0111] Although the information processing device 200 calculates the magnitude and direction of the force that the contact surface 10a is receiving from the object 2 based on the difference in the two-dimensional coordinates of the multiple dots 15a and 16a, the magnitude and direction of the force may be calculated based on changes in the size or shape of the multiple dots 15a. For example, if the multiple dots 15a are circular, the magnitude and direction of the force may be calculated based on changes in the size or shape of the circular dots. Here, the size of a circular dot refers to the area, circumference, radius, diameter, etc. of the dot.

[0112] The calculated magnitude and direction of the force may be presented on the display 206, or may be notified to a pre-registered smartphone, tablet, PC, etc. via the communication IF 204.

[0113] Furthermore, the information processing device 200 may calculate the shape of the portion of the object 2 that is in contact with the contact surface 10a, based on the shape of the recognized two-dimensional pattern 15. Note that, when the two-dimensional pattern 15 is composed of a plurality of dots, the shape of the two-dimensional pattern 15 refers to the shape of the arrangement of the plurality of dots.

[0114] 2. Effects, etc. The optical tactile sensor 100 according to this embodiment includes an elastic member 10, a holding member 20, a light source 30, and a camera 40. The elastic member 10 has a contact surface 10a that contacts the object 2. The holding member 20 has a transparent window 23, and holds the elastic member 10 in contact with it. The camera 40 photographs the shape of the contact surface 10a through the window 23. The elastic member 10 has a top layer 11 as a first portion and a bottom layer 14 as a second portion. The top layer 11 has a contact surface. The bottom layer 14 is formed integrally with the top layer 11 and is disposed between the top layer 11 and the window 23. The bottom layer 14 is harder than the top layer 11 and is in contact with the window 23 throughout the entire imaging range of the camera 40.

[0115] According to this, the bottom layer 14 of the elastic member 10 has a higher hardness than the top layer 11 having the contact surface 10a, and is in contact with the window portion 23 over the entire imaging range of the camera 40. In other words, the portion of the elastic member 10 that is in contact with the window portion 23 over the entire imaging range of the camera 40 is less likely to deform than the top layer 11. Therefore, even if an external load is applied to the contact surface 10a and the top layer 11 deforms, the bottom layer 14 is less likely to deform. This allows the camera 40 to capture an image in which the contact surface 10a is clearly reflected through the window portion 23. This makes it possible to prevent a decrease in the measurement accuracy of the measured mechanical quantity.

[0116] Furthermore, in the optical tactile sensor 100 according to this embodiment, the elastic member 10 is formed so that its hardness increases stepwise from the top layer 11 to the bottom layer 14. Therefore, when an external load is applied to the contact surface 10a and the top layer 11 deforms, the amount of deformation can be reduced stepwise toward the bottom layer 14. This makes it possible to make the bottom layer 14 less susceptible to deformation.

[0117] Furthermore, in the optical tactile sensor 100 according to this embodiment, the elastic member 10 is formed so that its hardness changes in three or more stages. Therefore, when an external load is applied to the contact surface 10a and the top layer 11 is deformed, the amount of deformation can be gradually reduced in three or more stages toward the bottom layer 14. This makes it possible to make the bottom layer 14 even more resistant to deformation.

[0118] In the optical tactile sensor 100 according to this embodiment, the elastic member 10 has a rear surface 10b and a side surface 10c that are different from each other and adjacent to each other. The holding member 20 has a window portion 23, and has a bottom surface member 21 that contacts the rear surface 10b and a side surface member 22 that contacts the side surface 10c.

[0119] According to this, the holding member 20 has the bottom member 21 and the side member 22, and is formed so as to cover not only the rear surface 10b side but also the side surface 10c side of the elastic member 10. As a result, the holding member 20 can hold the elastic member 10 so as to prevent deformation.

[0120] Furthermore, in the optical tactile sensor 100 according to this embodiment, the Shore A hardness of the remaining portions of the elastic member 10 excluding the bottom layer 14 is equal to or greater than 10 and equal to or less than 30. The Shore A hardness of the bottom layer 14 is 10 or more higher than that of the remaining portions. This makes it possible to improve measurement sensitivity in the remaining portions excluding the bottom layer 14, and to improve measurement accuracy with the bottom layer 14.

[0121] Furthermore, in the optical tactile sensor 100 according to this embodiment, the Shore A hardness of the bottom layer 14 is 20 or more higher than that of the remaining portions of the elastic member 10 excluding the bottom layer 14. This makes it possible to achieve a bottom layer 14 that is less likely to deform, thereby improving measurement accuracy.

[0122] Furthermore, in optical tactile sensor 100 according to this embodiment, the ratio of thickness TH1 of the remaining portion of elastic member 10 excluding bottom layer 14 to thickness TH2 of bottom layer 14 on line L1 connecting the center of contact surface 10a and the center of window portion 23 is between 2 and 9. This makes it possible to achieve the remaining portion excluding bottom layer 14 for improving measurement sensitivity, and bottom layer 14 for improving measurement accuracy.

[0123] Furthermore, in the optical tactile sensor 100 according to this embodiment, the holding member 20 is made entirely of a transparent material, which allows the holding member 20 to be made of a single type of material and is easily realized.

[0124] Furthermore, in the optical tactile sensor 100 according to this embodiment, the holding member 20 has an opening 24. The window portion 23 is a transparent plate-like member that covers the opening 24. Therefore, even if the holding member 20 is an opaque member, it is easy to make the imaging range of the camera 40 transparent.

[0125] [3. Modifications] (1) In the optical tactile sensor 100 according to the above embodiment, the top layer 11, the first intermediate layer 12, the second intermediate layer 13, and the bottom layer 14 each have a flat plate shape and are stacked in the front-to-back direction, but this is not limited to this. Figure 7 is a diagram showing an example cross-sectional view of an optical tactile sensor according to modification (1).

[0126] 7 , the components excluding the top layer 11A having the contact surface 10Aa of the elastic member 10A, i.e., the first intermediate layer 12A, the second intermediate layer 13A, and the bottom layer 14A, may have a shape that follows the shape of the holding member 20. That is, the first intermediate layer 12A may have a first portion 12Aa that follows the bottom member 21 of the holding member 20 and a second portion 12Ab that follows the side member 22. Similarly, the second intermediate layer 13A may have a first portion 13Aa that follows the bottom member 21 of the holding member 20 and a second portion 13Ab that follows the side member 22. Similarly, the bottom layer 14A may have a first portion 14Aa that follows the bottom member 21 of the holding member 20 and comes into contact with the bottom member 21, and a second portion 14Ab that follows the side member 22 and comes into contact with the side member 22. In this manner, the elastic member 10A has the bottom layer 14A having the first portion 14Aa and the second portion 14Ab, and therefore the bottom layer 14A has the rear surface 10Ab and the side surface 10Ac. Note that each of the second portions 12Ab, 13Ab, and 14Ab may have a uniform thickness.

[0127] According to the first modification, the bottom layer 14A has not only the rear surface 10Ab but also the side surface 10Ac, and is formed to cover not only the bottom surface side but also the side surface side of the top layer 11A, thereby making the bottom layer 14A less susceptible to deformation.

[0128] (2) In the elastic member 10A according to the above-described modification (1), each of the second portions 12Ab, 13Ab, and 14Ab has a uniform thickness, but this is not limited to this. Fig. 8 is a diagram showing an example of a cross-sectional view of the optical tactile sensor according to the modification (2).

[0129] 8 , the components excluding the top layer 11B having the contact surface 10Ba of the elastic member 10B, i.e., the first intermediate layer 12B, the second intermediate layer 13B, and the bottom layer 14B, may have a shape that follows the shape of the holding member 20. That is, the first intermediate layer 12B may have a first portion 12Ba that follows the bottom member 21 of the holding member 20 and a second portion 12Bb that follows the side member 22. Similarly, the second intermediate layer 13B may have a first portion 13Ba that follows the bottom member 21 of the holding member 20 and a second portion 13Bb that follows the side member 22. Similarly, the bottom layer 14B may have a first portion 14Ba that follows the bottom member 21 of the holding member 20 and comes into contact with the bottom member 21, and a second portion 14Bb that follows the side member 22 and comes into contact with the side member 22. In this manner, the elastic member 10B has the bottom layer 14B having the first portion 14Ba and the second portion 14Bb, and therefore the bottom layer 14B has the rear surface 10Bb and the side surface 10Bc. Here, unlike the second portions 12Ab, 13Ab, and 14Ab, the second portions 12Bb, 13Bb, and 14Bb may be configured to become thinner as they move away from the rear surface 10Bb.

[0130] Therefore, the volume of the top layer 11B can be made larger relative to the first intermediate layer 12B, the second intermediate layer 13B, and the bottom layer 14B as it moves away from the rear surface 10Bb. This makes it easier to deform the contact surface 10Ba of the elastic member 10B, and minimizes a decrease in measurement sensitivity. In other words, by forming the bottom layer 14B to cover the side surfaces of the top layer 11B, it is possible to make the bottom layer 14B less likely to deform and improve measurement sensitivity at the same time.

[0131] (3) In the optical tactile sensor 100 according to the above embodiment, the window portion 23 of the holding member 20 is disposed in a position that contacts the rear surface 10b of the elastic member 10, but this is not limited to this. Figure 9 is a diagram showing an example cross-sectional view of an optical tactile sensor according to modification (3).

[0132] 9 , the holding member 20C includes a bottom member 21C that supports the rear surface 10Cb of the elastic member 10C, and a side member 22C that supports the side surface 10Cc of the elastic member 10C. The side member 22C has an opening 24 and a window portion 23 that is a transparent plate-like member that closes the opening 24. The bottom member 21C and the side member 22C are connected so that the angle θ formed between the bottom member 21C and the side member 22C on which the window portion 23 is provided is between 90 degrees and 135 degrees. The side member 22C is an example of a first member, and the bottom member 21C is an example of a second member.

[0133] The elastic member 10C includes a top layer 11C, a first intermediate layer 12C, a second intermediate layer 13C, and a bottom layer 14C. The top layer 11C, the first intermediate layer 12C, the second intermediate layer 13C, and the bottom layer 14C are formed so that their boundary surfaces are inclined relative to the bottom member 21C. The bottom layer 14C is formed across the window portion 23 and the bottom member 21C, and is configured so that its boundary surface with the second intermediate layer 13C is inclined relative to the bottom member 21C. The top layer 11C, the first intermediate layer 12C, the second intermediate layer 13C, and the bottom layer 14C are each configured so that their thicknesses decrease toward the window portion 23. In this manner, the contact surface 10Ca and the side surface 10Cc that contacts the side member 22C having the window portion 23 are adjacent to each other. The contact surface 10Ca and the rear surface 10Cb face each other.

[0134] With this, because contact surface 10Ca and side surface 10Cc that contacts side surface member 22C having window portion 23 are adjacent to each other, camera 40 is positioned, for example, on the side surface side of elastic member 10C. In this way, camera 40 is not positioned on the opposite side of elastic member 10C from contact surface 10Ca, but is positioned to the side of elastic member 10C when elastic member 10C is viewed from the normal direction of contact surface 10Ca, which makes it possible to reduce the thickness of the optical tactile sensor in the normal direction to contact surface 10Ca.

[0135] (4) In the above embodiment, an example in which one light source 30 is arranged on a side of the elastic member 10 is illustrated. However, this is not limited to this. Three or more light sources may be arranged on the side of the elastic member 10. For example, the three or more light sources may be arranged so as to surround the elastic member 10 when viewed from the front. That is, the three or more light sources may be arranged in positions that emit light at different angles toward the center of the elastic member 10. Furthermore, the three or more light sources may emit light of different colors, and these colors may correspond to subpixels of the image sensor of the camera 40, respectively. For example, the three or more light sources may be red, green, and blue light sources, and the image sensor of the camera 40 may be a sensor in which each pixel has red, green, and blue subpixels.

[0136] As a result, red, green, and blue light from three light sources arranged on the sides of the elastic member 10 is irradiated onto the first layer 11a from three different directions. Therefore, when the contact surface 10a of the elastic member 10 is pressed and depressed, a shadow is created in the depressed portion with light of each color from each direction. In other words, because light is irradiated from three different directions, light blocking is reduced, and because the light from the three different directions is a different color, it is possible to distinguish between the light from each direction. The camera 40 captures an image including the shadows of the light of each color created by the depression of the contact surface 10a, and the image obtained by the camera 40 includes these shadows. Therefore, the information processing device 200 can identify the shape of an object pressed against the contact surface by analyzing the image.

[0137] The colors of the three or more light sources do not have to be different colors, and three or more light sources emitting light of the same color may be arranged on the sides of the elastic member 10. Furthermore, the number of light sources is not limited to three or more, and two or more light sources may be arranged on the sides of the elastic member 10. Furthermore, two or more light sources may be arranged behind the elastic member 10.

[0138] (5) In the above embodiment, the contact surface 10a is an outwardly convex curved surface, but it is not limited to an outwardly convex curved surface and may be a surface of another shape.

[0139] (6) Although the optical tactile sensor 100 according to the above embodiment and its modified examples is configured to include one camera 40, it may also be configured to include multiple cameras. The multiple cameras, like the camera 40, may be arranged behind the elastic member 10 so as to capture images of the first layer 11 a of the elastic member 10.

[0140] (7) Although the optical tactile sensors 100 according to the above embodiments and their modifications are configured to include a light source 30, it is not necessary to include a light source 30. For example, the camera 40 may capture natural light, ambient light, or light emitted from a light source located outside the optical tactile sensor 100, reflected by the first layer 11a. In this case, the optical tactile sensor may include a light guide that guides the natural light, ambient light, or light emitted from a light source located outside the optical tactile sensor 100 to the first layer 11a.

[0141] While the optical tactile sensor according to one or more aspects of the present disclosure has been described above based on the embodiments, the present disclosure is not limited to these embodiments. As long as they do not deviate from the spirit of the present disclosure, various modifications conceivable by those skilled in the art to the present embodiments and configurations constructed by combining components of different embodiments may also be included within the scope of the present disclosure.

[0142] The present disclosure is useful as an optical tactile sensor or the like that can suppress a decrease in measurement accuracy.

[0143] 1 Sensor system 2 Object 10, 10A to 10C Elastic member 10a, 10Aa to 10Ca Contact surface 10b, 10Ab to 10Cb Rear surface 10c, 10Ac to 10Cc Side surface 11, 11A to 11C Top layer 11a First layer 11b Second layer 12, 12A to 12C First intermediate layer 13, 13A to 13C Second intermediate layer 14, 14A to 14C Bottom layer 12Aa to 12Ca, 13Aa to 13Ca, 14Aa to 14Ca First part 12Ab to 12Cb, 13Ab to 13Cb, 14Ab to 14Cb Second part 15 Two-dimensional pattern 15a, 16a Multiple dots 15b, 16b center 20, 20C Holding member 21 Bottom member 22 Side member 23 Window portion 24 Opening 30 Light source 40 Camera 50 Image data 51, 52 Image 100 Optical tactile sensor 200 Information processing device 201 Processor 202 Main memory 203 Storage 204 Communication IF (Interface) 205 Input IF (Interface) 206 Display

Claims

1. an elastic member having a contact surface to be brought into contact with an object; a holding member having a transparent window portion and contacting and holding the elastic member; A light source; a camera that captures an image of the shape of the contact surface through the window, The elastic member is a first portion having the contact surface; a transparent second portion integrally formed with the first portion and disposed between the first portion and the window portion; The second portion has a harder hardness than the first portion. Optical tactile sensor.

2. The second part is in contact with the window part over the entire shooting range of the camera. The optical tactile sensor according to claim 1 .

3. The elastic member is formed so as to have a gradually increasing hardness from the first portion toward the second portion. The optical tactile sensor according to claim 1 .

4. The elastic member is formed so that the hardness gradually increases from the first portion to the second portion. The optical tactile sensor according to claim 1 .

5. The elastic member is formed so that the hardness changes in three or more stages. The optical tactile sensor according to claim 4 .

6. the elastic member has first and second surfaces that are distinct and adjacent to each other; the holding member has a first member in contact with the first surface and a second member in contact with the second surface, The first member has the window portion, The second portion has the first surface and the second surface. The optical tactile sensor according to claim 1 .

7. The second portion has a thickness that decreases as it gets farther from the first surface. The optical tactile sensor according to claim 6 .

8. the contact surface and the first surface are adjacent to each other; The contact surface and the second surface face each other, The angle between the first member and the second member on which the elastic member is disposed is equal to or greater than 90 degrees and equal to or less than 135 degrees. The optical tactile sensor according to claim 6 .

9. The Shore A hardness of the elastic member other than the second portion is 10° or more and 30° or less, The Shore A hardness of the second portion is 10° or more higher than that of the other portion. The optical tactile sensor according to claim 1 .

10. The Shore A hardness of the second portion is 20° or more higher than that of the other portion. The optical tactile sensor according to claim 9 .

11. A ratio of a thickness of the second portion to a thickness of the other portion of the elastic member excluding the second portion on a straight line connecting the center of the contact surface and the center of the window portion is 2 or more and 9 or less. The optical tactile sensor according to claim 1 .

12. The holding member is entirely made of a transparent material. The optical tactile sensor according to claim 1 .

13. The holding member has an opening, The window portion is a transparent plate-like member that closes the opening. The optical tactile sensor according to claim 1 .

14. An elastic member having a contact surface for contacting an object; a holding member having a transparent window portion and contacting and holding the elastic member; A light source; a camera that captures an image of the shape of the contact surface through the window, The elastic member is a first portion having the contact surface; a transparent second portion integrally formed with the first portion and disposed between the first portion and the window portion; The second portion is in contact with the window portion over the entire photographing range of the camera. Optical tactile sensor.

15. An optical tactile sensor according to any one of claims 1 to 8 and 14; and an information processing device that acquires a plurality of images obtained by the camera photographing the contact surface at different times, calculates a movement of the contact surface using the plurality of images, and calculates at least one of a force acting on the contact surface from the object and a change in the force. Sensor system.