Tactile sensor

Abstract

Provided is a tactile sensor capable of suppressing a decrease in spatial resolution and sensitivity of a sensor element, and having waterproofness and dustproofness. A tactile sensor (AA) has a sensor element (1) and a housing (2) that houses the sensor element (1). The sensor element (1) has a base (10), a contact (20A) having a contact end, a support body that supports the contact (20A) so as to be displaceable with respect to the base, and a displacement detector that detects displacement of the contact (20A) with respect to the base (10). The housing (2) has a flexible film that covers at least the contact end in the sensor element (1). The contact end is fixed to an inner surface of the film (60).

Description

Technical Field

[0001] This invention relates to tactile sensors. More specifically, this invention relates to tactile sensors intended for the quantification of human tactile sensation. Background Technology

[0002] It is claimed that the human fingertip can detect minute textures of approximately 100μm and minute forces of approximately 100μN. Because of this high spatial resolution and sensitivity, humans can perceive the texture / feel of objects they touch. In the medical field, this tactile sense is used by doctors to diagnose the condition of affected areas by directly touching them with their fingers. However, tactile examination cannot be performed during endoscopic and robotic surgeries. Therefore, it is necessary to install tactile sensors on endoscopes and other devices to provide doctors with tactile information from within the body.

[0003] Various structures have been developed as tactile sensors that ergonomically simulate human touch. For example, Patent Document 1 discloses a tactile sensor with tiny contacts. By pushing the tactile sensor against the object being measured and sliding it, the displacement of the contacts can be measured to detect the minute irregularities and frictional forces in small areas of the object's surface.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2015 / 133113

[0007] Patent Document 2: Japanese Patent Application Publication No. 2011-85435 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, the tactile sensor in Patent Document 1 exposes its fine mechanical structure. If such a tactile sensor comes into contact with internal organs, blood can enter the gaps in the mechanical structure and coagulate, hindering the movement of the mechanical structure. The same applies when measuring objects other than internal organs. If dust adhering to the surface of the object being measured enters the gaps, the movement of the mechanical structure is hindered. Furthermore, there are cases where liquid adhering to the surface of the object being measured can cause a short circuit in the detection circuit. Therefore, in order to create a tactile sensor that can withstand practical use, it is necessary to protect the tactile sensor from liquids and dust.

[0010] Patent Document 2 discloses a tactile sensor in which the sensor element is embedded inside a resin block. This structure protects the sensor element from liquids and dust. However, in this structure, the spatial resolution and sensitivity of the tactile sensor decrease because the force exerted on the object being measured is dispersed by the resin block. Therefore, it is not suitable for obtaining tactile information as a substitute for palpation.

[0011] In view of the above, the present invention aims to provide a tactile sensor that can suppress the decrease in spatial resolution and sensitivity of sensor elements and has waterproof and dustproof properties.

[0012] Methods used to solve problems

[0013] The tactile sensor of the first technical solution is characterized by comprising: a sensor element; and a housing for housing the sensor element; the sensor element comprising: a base; a contact having a contact end; a support for displaceably supporting the contact relative to the base; and a displacement detector for detecting the displacement of the contact relative to the base; the housing comprising a flexible membrane covering at least the contact end of the sensor element; the contact end being fixed to the inner surface of the membrane.

[0014] The second technical solution of the tactile sensor is characterized in that the membrane has an adhesive layer on its inner surface, and the contact end is adhered to the membrane by the adhesive layer.

[0015] The tactile sensor of the third technical solution is characterized in that the contact end has a pin that bites into the membrane.

[0016] The tactile sensor of the fourth technical solution is characterized in that the housing further comprises a housing body having an opening; the opening is sealed by the membrane; the contact end is disposed in the opening; and the base is fixed relative to the housing body.

[0017] The tactile sensor of the fifth technical solution is characterized in that the housing body comprises: a frame having the opening, wherein the film is adhered to the adhesive surface where the opening is located; and an outer body covering the portion of the film other than the portion corresponding to the opening.

[0018] The tactile sensor of the sixth technical solution is characterized in that the end of the opening in the sweeping direction is semi-elliptical or semi-circular.

[0019] The tactile sensor of the seventh technical solution is characterized in that the frame has an inclined surface at the end in the sweeping direction, as described in the fifth or sixth technical solution.

[0020] Invention Effects

[0021] According to the first technical solution, since the sensor element is housed within the housing, liquids and dust do not penetrate the sensor element. Therefore, the tactile sensor is waterproof and dustproof. Furthermore, since the contact end is fixed to the inner surface of the membrane, the contact moves in accordance with the movement of the membrane that is in direct contact with the object being measured. Therefore, the decrease in the spatial resolution and sensitivity of the sensor element can be suppressed.

[0022] According to the second technical solution, since the contact end is adhered to the membrane, the force exerted on the membrane by the object being measured is easily transmitted to the contact.

[0023] According to the third technical solution, since the contact end is fixed to the membrane by a nail, the force exerted on the membrane by the object being measured is easily transmitted to the contact.

[0024] According to the fourth technical solution, since the membrane is provided on the main body of the shell, the membrane is easier to fix.

[0025] According to the fifth technical solution, since a portion of the membrane is covered by the outer casing, the contact area between the membrane and the object being measured is reduced. Therefore, it is possible to suppress the membrane from rubbing against the object being measured and breaking.

[0026] According to the sixth technical solution, since the end of the opening is semi-elliptical or semi-circular, it can mitigate the stress concentration that occurs on the membrane during sweeping and suppress membrane rupture.

[0027] According to the seventh technical solution, since the end of the frame is tilted, even if the tactile sensor tilts forward during sweeping, it is less likely that a strong force will be applied to a part of the membrane, thus suppressing membrane rupture. Attached Figure Description

[0028] Figure 1 This is a top view of the sensor element according to the first embodiment.

[0029] Figure 2 (A) is an explanatory diagram of the first and second strain detection elements under the condition that there is no strain in the crossbeam of the support. Figure 2 (B) is an explanatory diagram of the first and second strain detection elements under the condition that there is strain in the crossbeam of the support.

[0030] Figure 3 This is a circuit diagram representing a strain detection circuit.

[0031] Figure 4(A) is an explanatory diagram of the third and fourth strain detection elements under the condition that there is no strain in the longitudinal beam of the support. Figure 4 (B) is an explanatory diagram of the third and fourth strain detection elements under the condition that there is strain in the longitudinal beam of the support.

[0032] Figure 5 This is an illustration of a tactile measurement method when the sensor element is used alone.

[0033] Figure 6 It is a graph illustrating various signals obtained from sensor elements.

[0034] Figure 7 This is a longitudinal sectional view of the tactile sensor according to the first embodiment.

[0035] Figure 8 It is an exploded view of the sensor components, frame, and membrane.

[0036] Figure 9 It is an exploded view of the sensor components, frame, and outer casing.

[0037] Figure 10 This is a 3D diagram of a tactile sensor.

[0038] Figure 11 This is an enlarged view of the front end of the contact.

[0039] Figure 12 (A) is an enlarged view of the case where the adhesive film is bonded to the contact. Figure 12 (B) is an enlarged view showing the contact pins biting into the membrane.

[0040] Figure 13 (A) is an enlarged view of the opening of a certain shape. Figure 13 (B) is an enlarged view of the opening in another form.

[0041] Figure 14 This is an explanatory diagram of the tactile measurement method of a tactile sensor.

[0042] Figure 15 This is an illustration showing the tactile sensor tilted forward.

[0043] Figure 16 This is a perspective view of the sensor element according to the second embodiment.

[0044] Figure 17 This is an explanatory diagram of the tactile measurement method of the tactile sensor according to the second embodiment.

[0045] Figure 18 (A) is a graph representing the reaction force corresponding to the displacement in the z-axis direction. Figure 18(B) is a graph representing the reaction force corresponding to the displacement in the x-axis direction.

[0046] Figure 19 This is a graph representing the results of measuring a roughness standard piece with a spacing of approximately 250 μm.

[0047] Figure 20 This is a graph representing the results of measuring the roughness of a standard sample with a 32μm pitch.

[0048] Figure 21 (A) is a graph showing the sensitivity of measuring the z-axis direction in air. Figure 21 (B) is a graph showing the sensitivity of the measurement in the z-axis direction in water.

[0049] Figure 22 It is a graph showing the coefficient of friction of a glass plate measured in air, water, and glycerin.

[0050] Figure 23 It is a graph representing the results of measuring the tactile sensation of simulated internal organs. Detailed Implementation

[0051] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

[0052] [First Embodiment]

[0053] (Sensor element)

[0054] The tactile sensor according to the first embodiment of the present invention has a sensor element. The structure of the sensor element is not particularly limited, and for example, it can be made into the following structure.

[0055] like Figure 1 As shown, sensor element 1 is formed by processing a semiconductor substrate using semiconductor microfabrication technology. The mechanical structure of sensor element 1 is formed by removing unwanted portions of the semiconductor substrate through etching in a predetermined pattern. Therefore, sensor element 1 is generally flat. The overall size of sensor element 1 is not particularly limited, and is, for example, a square shape of 1–20 mm.

[0056] Sensor element 1 uses one side as a sensing surface to receive force from the object being measured. In this embodiment, the side of sensor element 1... Figure 1 The upper side of the middle is used as the sensing surface.

[0057] The sensor element 1 has a generally rectangular base 10. A space 11 is formed in the central portion of the base 10. Furthermore, a gap 13 is formed in the center of the edge 12 on the sensing surface side of the base 10. The space 11 communicates with the outside of the base 10 via the gap 13.

[0058] The side surface of the edge portion 12 that forms part of the sensing surface is referred to as the reference surface 14. The reference surface 14 is divided into two by the gap 13. In addition, one of the reference surfaces 14 is disposed in the surface that extends the other reference surface 14.

[0059] Hereinafter, the x-axis, y-axis, and z-axis are defined with reference plane 14 as the reference. The x-axis and y-axis are axes parallel to reference plane 14. The y-axis is perpendicular to the x-axis. The x-axis is along the width direction of sensor element 1, and the y-axis is along the thickness direction of sensor element 1. The z-axis is an axis perpendicular to reference plane 14. The x-z plane is parallel to the main surface of the front and back surfaces of the plate-shaped sensor element 1. The direction along the x-axis is called the x-axis direction, the direction along the y-axis is called the y-axis direction, and the direction along the z-axis is called the z-axis direction.

[0060] A plurality of contacts 20A to 20F are disposed in the gap 13 of the base 10. The number of contacts 20A to 20F is not particularly limited; the sensor element 1 of this embodiment has six contacts 20A to 20F. Alternatively, the number of contacts 20A to 20F may be set to one.

[0061] Each contact 20A to 20F is a rod-shaped component with its central axis arranged along the z-axis. Furthermore, multiple contacts 20A to 20F are arranged along the x-axis. The contacts 20A to 20F are arranged between two reference surfaces 14, 14 (edge ​​portions 12, 12).

[0062] Preferably, the front ends of contacts 20A to 20F protrude outward from the reference surface 14. The front ends of each contact 20A to 20F are referred to as contact ends 21. The side surface of contact ends 21 forms part of the sensing surface. The shape of contact ends 21 is not particularly limited, as long as it is made into a semi-circle or a fan shape.

[0063] Typically, the contact ends 21 of all contacts 20A to 20F are designed to have the same shape and size. Furthermore, contacts 20A to 20F are usually arranged at equal intervals along the x-axis. The spacing (center-to-center distance) between adjacent contacts 20A and 20B is not particularly limited, but is preferably 300 to 700 μm, for example, 500 μm. This is similar to the spacing of the ridges that form a human fingerprint. In this way, it is conceivable that sensor element 1 can perform tactile detection close to that of a human.

[0064] From the viewpoint of achieving detection that approximates human touch, the contact end 21 preferably has the same shape and size as the cross-section of the raised lines constituting a fingerprint. Specifically, it is preferable to make the contact end 21 semi-circular, with a diameter of 100 to 500 μm.

[0065] A gap is provided between contacts 20A to 20F. Therefore, the width dimension of each contact 20A to 20F is smaller than the spacing between adjacent contacts 20A and 20B. The width dimension of each contact 20A to 20F is, for example, 200 to 600 μm. Because of the gap between contacts 20A to 20F, contacts 20A to 20F can be displaced independently.

[0066] A plurality of supports 30A to 30F are disposed in the space portion 11 of the base 10. The supports 30A to 30F support a plurality of contacts 20A to 20F respectively relative to the base 10. The number of supports 30A to 30F is equal to the number of contacts 20A to 20F. The sensor element 1 of this embodiment has six supports 30A to 30F. Each contact 20A to 20F is supported by its corresponding support 30A to 30F.

[0067] For example, the first contact 20A is connected to the base 10 via a first support 30A. The support 30A consists of one or more crossbeams 31, one or more longitudinal beams 32, and a connecting portion 33. The crossbeams 31 are installed between the contact 20A and the connecting portion 33. The longitudinal beams 32 are installed between the connecting portion 33 and the base 10. Alternatively, the longitudinal beams 32 can be installed between the contact 20A and the connecting portion 33, and the crossbeams 31 can be installed between the connecting portion 33 and the base 10.

[0068] The crossbeam 31 is elastic, possessing the same properties as a leaf spring. Furthermore, the crossbeam 31 is positioned along the x-axis. Therefore, the crossbeam 31 allows displacement of the contact 20A in the z-axis direction. The longitudinal beam 32 is elastic, possessing the same properties as a leaf spring. Furthermore, the longitudinal beam 32 is positioned along the z-axis. Therefore, the longitudinal beam 32 allows displacement of the contact 20A in the x-axis direction. That is, the contact 20A is supported relative to the reference surface 14 in a manner that allows displacement in both the x-axis and z-axis directions.

[0069] The number and dimensions (length and width) of the crossbeams 31 and longitudinal beams 32 constituting the support 30A are not specifically limited. As long as the number and dimensions of the crossbeams 31 and longitudinal beams 32 are set so that the support 30A can obtain the required elasticity.

[0070] The other supports 30B to 30F have the same structure as the first support 30A. The other contacts 20B to 20F are also supported so as to be displaceable relative to the reference plane 14 in the x-axis and z-axis directions. In addition, the supports 30A to 30F can be constructed from components other than beams, as long as the desired elasticity can be obtained.

[0071] If a normal force (force in the z-axis direction) is applied to the sensing surface of sensor element 1, contacts 20A to 20F will displace in the z-axis direction. Furthermore, if a tangential force (force in the x-axis direction) is applied to the sensing surface of sensor element 1, contacts 20A to 20F will displace in the x-axis direction. Multiple displacement detectors 40A to 40F are provided to detect these displacements of contacts 20A to 20F.

[0072] The number of displacement detectors 40A to 40F is equal to the number of contacts 20A to 20F. The sensor element 1 of this embodiment has six displacement detectors 40A to 40F. The displacement of each contact 20A to 20F relative to the reference surface 14 can be independently detected by the displacement detectors 40A to 40F. Each displacement detector 40A to 40F is located on its corresponding support 30A to 30F.

[0073] For example, a first displacement detector 40A is provided on the first support 30. The first displacement detector 40A can detect the displacement of the first contact 20A relative to the reference surface 14. The displacement detector 40A is composed of a longitudinal displacement detector 41 that detects the displacement of the contact 20A in the z-axis direction and a transverse displacement detector 42 that detects the displacement of the contact 20A in the x-axis direction.

[0074] like Figure 2 As shown in (A), the longitudinal displacement detector 41 is composed of first and second strain detection elements 43 and 44 for detecting the strain of the crossbeam 31. Piezoelectric resistor elements can be used as the first and second strain detection elements 43 and 44. Piezoelectric resistor elements can be formed on the surface of a semiconductor substrate using integrated circuit manufacturing processes such as impurity diffusion and ion implantation, or metal wiring formation techniques.

[0075] A first strain detection element 43 is formed on the surface of one of the multiple crossbeams 31 constituting the support 30A. Furthermore, a second strain detection element 44 is formed on the surface of the other crossbeam 31. The first and second strain detection elements 43 and 44 are respectively formed in a stepped shape, having a shape that extends from one end of the crossbeam 31 along one side and from the center to the other end along the other side. Moreover, the first strain detection element 43 formed on one crossbeam 31 and the second strain detection element 44 formed on the other crossbeam 31 have shapes that are linearly symmetrical to each other.

[0076] like Figure 2As shown in (B), if contact 20A is displaced in the z-axis direction, strain occurs in the beam 31. At this time, if the first and second strain sensing elements 43 and 44 are made of materials exhibiting a positive piezoelectric resistivity, the resistance of the first strain sensing element 43 increases due to tensile stress, and the resistance of the second strain sensing element 44 decreases due to compressive stress. If the displacement direction of contact 20A is opposite, the resistance of the first strain sensing element 43 decreases due to compressive stress, and the resistance of the second strain sensing element 44 increases due to tensile stress.

[0077] like Figure 3 As shown, a strain detection circuit for detecting the strain of the crossbeam 31 is formed on the surface of the sensor element 1. Figure 1 and Figure 2 (Not shown in the diagram). The strain detection circuit is a circuit that connects the first and second strain detection elements 43 and 44 in series, applies a voltage Vdd across their terminals, and reads the voltage Vout between the first strain detection element 43 and the second strain detection element 44. The voltage Vout varies due to the differential of the first and second strain detection elements 43 and 44. By reading the voltage Vout, the strain of the crossbeam 31 can be detected. Thus, the displacement of the contact 20A relative to the reference plane 14 in the z-axis direction can be detected by the longitudinal displacement detector 41.

[0078] like Figure 4 As shown in (A), the transverse displacement detector 42 is composed of third and fourth strain detection elements 45 and 46 for detecting the strain of the longitudinal beam 32. Piezoelectric elements can be used as the third and fourth strain detection elements 45 and 46.

[0079] A third strain detection element 45 is formed on the surface of one of the longitudinal beams 32 constituting the support 30A. Furthermore, a fourth strain detection element 46 is formed on the surface of the other longitudinal beam 32. The third and fourth strain detection elements 45 and 46 are formed in a symmetrical stepped shape.

[0080] like Figure 4 As shown in (B), if contact 20A is displaced in the x-axis direction, strain occurs in the longitudinal beam 32. At this time, if the third and fourth strain sensing elements 45 and 46 are made of materials exhibiting a positive piezoelectric resistivity, the resistance of the third strain sensing element 45 increases due to tensile stress, and the resistance of the fourth strain sensing element 46 decreases due to compressive stress. If the displacement direction of contact 20A is opposite, the resistance of the third strain sensing element 45 decreases due to compressive stress, and the resistance of the fourth strain sensing element 46 increases due to tensile stress.

[0081] A strain detection circuit for detecting the strain of the longitudinal beam 32 is formed on the surface of sensor element 1. Figure 1 and Figure 4(Not shown in the diagram). This circuit is in Figure 3 The circuit shown replaces the first strain detection element 43 with the third strain detection element 45 and the second strain detection element 44 with the fourth strain detection element 46. The strain of the longitudinal beam 32 is detected by the strain detection circuit. Thus, the displacement of the contact 20A relative to the reference plane 14 in the x-axis direction can be detected by the transverse displacement detector 42.

[0082] The other displacement detectors 40B to 40F have the same structure as the first displacement detector 40A. Furthermore, the first to fourth strain detection elements 43 to 46 are not limited to piezoelectric elements. For example, the displacement detectors 40A to 40F can be configured to detect the electrostatic capacitance between the contacts 20A to 20F and the base 10 by utilizing the change in distance between the contacts 20A to 20F and the base 10 caused by the displacement of the contacts 20A to 20F.

[0083] Sensor element 1 can be manufactured, for example, by processing an SOI substrate in the following order. Here, the SOI substrate has a three-layer structure consisting of a support substrate (silicon), an oxide layer (silicon dioxide), and an active layer (silicon), with a thickness of, for example, 300 μm.

[0084] First, the substrate is cleaned and oxidized to form a surface oxide film. Next, the surface oxide film is processed to form a diffusion layer pattern for the circuit components, followed by phosphorus diffusion. Then, a piezoelectric resistor element is formed by phosphorus ion implantation and thermal annealing. Next, a chromium thin film is sputtered onto the back side of the substrate, and the chromium film is patterned to allow the movable components (contacts 20A-20F and supports 30A-30F) to be molded. Next, the surface oxide film is removed, and the movable components are etched using ICP-RIE to form the movable components. After protecting the formed movable components by filling the periphery with photoresist, the back side is etched using ICP-RIE. Finally, the intermediate oxide film and photoresist are removed, and the movable components are demolded.

[0085] Furthermore, the manufacturing method of sensor element 1 is not limited to semiconductor microfabrication technology. For example, sensor element 1, either as a whole or in part, can also be formed using 3D printing molding technology.

[0086] Next, the tactile measurement method when using sensor element 1 alone will be described.

[0087] When using sensor element 1 for measurement, the sensing surface of sensor element 1 is pressed against the object being measured while being swept. In this way, contacts 20A to 20F are displaced in the x-axis and z-axis directions. Based on this displacement, the surface shape, friction, and other properties of the object being measured can be measured. The principle is explained below.

[0088] exist Figure 5The movement of a single contact 20 is represented in the figure. When the sensing surface of the sensor element 1 is pressed against the object being measured O, the reference surface 14 is positioned on a plane that connects the uneven peaks of the surface of the object being measured O. Furthermore, the contact 20 is pushed in by the reaction force of the pushing force of the sensor element 1, and displaced in the z-axis direction.

[0089] With the sensing surface of sensor element 1 pressed against the object being measured O, the sensor element 1 is swept along the surface of the object being measured O. Furthermore, the sweeping is performed in the x-axis direction. Therefore, the x-axis direction is also referred to as the sweeping direction. When sensor element 1 is swept, contact 20 is displaced in the z-axis direction along the unevenness of the surface of the object being measured O. Additionally, contact 20 is displaced in the x-axis direction by the frictional force acting between contact end 21 and the object being measured O.

[0090] exist Figure 6 The above describes examples of various signals obtained from sensor element 1 through the above operations.

[0091] In the curve (1), the horizontal axis represents time, and the vertical axis represents the displacement of the contact 20 in the z-axis direction detected by the vertical displacement detector 41. When the sensor element 1 is swept along the surface of the object being measured O at a fixed speed, the horizontal axis is synonymous with the position coordinates of the surface of the object being measured O. The displacement of the contact 20 in the z-axis direction means the amount of unevenness or roughness of the surface of the object being measured O. Therefore, the curve (1) reproduces the surface shape (spatial waveform) of the surface of the object being measured O.

[0092] In the curve (2), the horizontal axis represents time, and the vertical axis represents the displacement of the contact 20 in the x-axis direction detected by the horizontal displacement detector 42. The displacement of the contact 20 in the x-axis direction means the frictional force acting between the contact end 21 and the object being measured O. Here, since the contact area between the contact end 21 and the object being measured O is small, the displacement of the contact 20 in the x-axis direction means the frictional force in a small area.

[0093] Based on the displacements of contact 20 along the x-axis and z-axis, the coefficient of kinetic friction μ of a small region on the surface of the object O being measured can be determined. Since the elastic modulus of beam 31 is known, the vertical load f acting on contact 20 can be calculated based on the displacement of contact 20 along the z-axis. z Furthermore, since the elastic modulus of the longitudinal beam 32 is known, the frictional force f acting on the contact 20 can be calculated based on the displacement of the contact 20 in the x-axis direction. x According to the following equation (1), it is possible to determine the vertical load f. z and frictional force f x The coefficient of kinetic friction μ of a small area on the surface of the object O is calculated.

[0094] [Formula 1]

[0095] μ = f x / f y …(1)

[0096] As described above, by detecting the displacement of the contact 20 in the x-axis and z-axis directions, the fine characteristics of the surface of the object O being measured, namely the fine irregularities and friction in small areas, can be detected.

[0097] The sensor element 1 of this embodiment has multiple contacts 20A to 20F, and can detect the displacement of each of the contacts 20A to 20F. Therefore, if the above operation is performed using the sensor element 1, multiple measurements can be performed simultaneously. As a result, the surface characteristics of the object to be measured O can be detected at multiple points with high spatial resolution.

[0098] (case)

[0099] like Figure 1 As shown, the fine mechanical structure of sensor element 1 is exposed. Therefore, as Figure 5 As shown, if the sensing surface is brought into direct contact with the object being measured (O) and the sensor element 1 is swept across it, liquid or dust adhering to the surface of the object being measured (O) will enter the gaps in the mechanical structure. If this happens, the movement of the mechanical structure will be impeded, and the measurement accuracy will decrease.

[0100] Therefore, as Figure 7 As shown, the tactile sensor AA of this embodiment has a housing 2 that houses the sensor element 1. Since the sensor element 1 is housed in the housing 2, liquids and dust do not penetrate into the sensor element 1. That is, the tactile sensor AA is waterproof and dustproof.

[0101] The housing 2 has a housing body 50 consisting of a frame 51 and an outer casing 52. An opening 53 is formed on the housing body 50. The opening 53 is sealed by a membrane 60. The sensing surface of the sensor element 1 is disposed in the opening 53 and is in close contact with the membrane 60. When the tactile sensor AA measures tactile sensation, the membrane 60 is in direct contact with the object being measured O, and the sensing surface of the sensor element 1 is in indirect contact with the object being measured O via the membrane 60 (see reference). Figure 14 Therefore, the sensor element 1 is protected from liquids and dust by the membrane 60.

[0102] like Figure 8As shown, frame 51 is a generally plate-shaped component. The surface of frame 51 (one main surface) is a frustum-shaped square pyramid protruding outwards from its central portion. This frustum-shaped surface is called the adhesive surface 54. Inside frame 51, a slit 55 is formed, extending from the adhesive surface 54 (surface) to the back surface. The slit 55 opens at the central portion of the adhesive surface 54, i.e., the most protruding part. This opening in the adhesive surface 54 is called opening 53. Both slit 55 and opening 53 are horizontally elongated, with their x-axis dimension slightly longer than the width of sensor element 1. Furthermore, the y-axis dimension of slit 55 and opening 53 is slightly longer than the thickness of sensor element 1.

[0103] A membrane 60 is adhered to the adhesive surface 54 of the frame 51. Therefore, the opening 53 is sealed by the membrane 60. Furthermore, the membrane 60 only needs to seal the opening 53; it does not need to be adhered to the entire adhesive surface 54.

[0104] Sensor element 1 is inserted into slit 55 from the back of frame 51. Once inserted into slit 55, the sensing surface of sensor element 1 reaches membrane 60.

[0105] like Figure 9 As shown, the frame 51 and sensor element 1 are inserted inside the outer casing 52. The outer casing 52 is a generally cuboid component with an internal space. A window 56 is formed on one side of the outer casing 52, communicating between the interior and the exterior. The window 56 is an opening that is slightly larger than the opening 53.

[0106] like Figure 10 As shown, when the frame 51 is combined with the outer casing 52, the central portion of the protruding adhesive surface 54 is positioned within the window 56. That is, the entire opening 53 is positioned within the window 56. Furthermore, the portion of the membrane 60 corresponding to the opening 53 and its surrounding area protrudes from the window 56, while the remaining portion is covered by the outer casing 52.

[0107] like Figure 7 As shown, the frame 51 is fixed relative to the outer body 52. ​​The method of fixing the frame 51 and the outer body 52 is not particularly limited; the frame 51 can be snapped onto the protrusion provided on the outer body 52, or it can be tightly connected with bolts, nuts, or other fastening tools.

[0108] Furthermore, the base 10 of the sensor element 1 is fixed relative to the housing body 50. The base 10 can be fixed in a manner that prevents it from moving relative to the housing body 50; it can be directly fixed or indirectly fixed to the housing body 50 via other components. The fixing method is not particularly limited. Additionally, the movable structural parts of the sensor element 1 (contacts 20A-20F and supports 30A-30F) are movable relative to the housing body 50.

[0109] The contact ends 21 of the contacts 20A to 20F of the sensor element 1 can also be arranged in the same plane as the opening 53, but preferably they protrude outward from the opening 53. If so, then... Figure 11 As shown, the membrane 60 is pushed against the front end of the contacts 20A-20F and partially elongates along the shape of the contact end 21. Thus, the shape of the contact end 21 is formed on the outer surface of the membrane 60. Furthermore, the membrane 60 is preferably also in close contact with the reference surface 14.

[0110] Membrane 60 can be any flexible membrane. Resin membranes such as polyurethane and latex can be used as membrane 60. From the viewpoint of quality stability and durability, it is preferable to use a medical membrane that is used as a raw material for adhesive bandages or medical gloves as membrane 60.

[0111] When measuring tactile sensation, membrane 60 is sandwiched between contacts 20A-20F and the object being measured, O (see reference). Figure 14 To prevent the force received from the object being measured from being dispersed or attenuated and transmitted to the contacts 20A-20F, the membrane 60 is preferably thin. On the other hand, the membrane 60 needs to have a degree of durability that prevents it from breaking even when rubbed against the object being measured. That is, the membrane 60 is preferably thin as long as it has a certain degree of durability. For example, an 8μm thick medical membrane (polyurethane membrane) is sufficiently thin and also has sufficient durability.

[0112] The thickness of the membrane 60 is preferably sufficiently thin compared to the diameter of the contact end 21. Specifically, the thickness of the membrane 60 is preferably less than or equal to the diameter of the contact end 21, more preferably less than or equal to half the diameter, and even more preferably less than or equal to one-third of the diameter. For example, if the diameter of the contact end 21 is 500 μm, the thickness of the membrane 60 is preferably less than or equal to 500 μm, more preferably less than or equal to 250 μm, and even more preferably less than or equal to 170 μm. In this case, the force received from the object being measured is not significantly dispersed or attenuated, thus maintaining the performance (spatial resolution and sensitivity) of the sensor element 1.

[0113] The contact ends 21 of each contact 20A to 20F are fixed to the inner surface of the membrane 60. A frictional force acts between the outer surface of the membrane 60 and the object being measured. The contact ends 21 are fixed so that they do not shift relative to the membrane 60 against this frictional force. The method of fixing the contact ends 21 to the membrane 60 is not particularly limited; for example, the following methods can be used.

[0114] like Figure 12As shown in (A), the membrane 60 can be any membrane with a layered structure having a base layer 61 and an adhesive layer 62, i.e., an adhesive membrane. The membrane 60 is provided with the adhesive layer 62 as its inner surface. The contact end 21 is bonded to the membrane 60 by the adhesive layer 62. In addition, if an adhesive membrane is used as the membrane 60, it is also easier to attach it to the frame 51.

[0115] like Figure 12 As shown in (B), a pin 22 can also be provided on the contact end 21, so that the pin 22 bites into the membrane 60. The number of pins 22 is not particularly limited, and there can be one or more. In order to suppress the rupture of the membrane 60 caused by the pins 22, the length of the pins 22 is preferably less than half the thickness of the membrane 60. In addition, a pin 22 can be provided on the contact end 21 and an adhesive membrane can be used as the membrane 60.

[0116] Thus, by bonding the contact end 21 to the membrane 60, or by fixing the contact end 21 to the membrane 60 with the nail 22, the contact end 21 no longer shifts relative to the membrane 60. Therefore, the force exerted on the membrane 60 by the object being measured is easily transmitted to the contacts 20A to 20F.

[0117] The sensor element 1 in this embodiment has a horizontally elongated sensing surface. Therefore, as... Figure 13 As shown in (A), the opening 53 only needs to be made into a rectangle that is longer in the width direction (x-axis direction) of the sensor element 1. During tactile measurement, the membrane 60 rubs against the object being measured in the sweeping direction (x-axis direction). Therefore, wrinkles easily form on the membrane 60 at the sweeping end of the opening 53. These wrinkles may cause the membrane 60 to rupture.

[0118] Therefore, as Figure 13 As shown in (B), the opening 53 is preferably made into a semi-elliptical or semi-circular shape at its end in the sweeping direction. If this is done, stress concentration that occurs on the membrane 60 during sweeping can be suppressed, and the rupture of the membrane 60 can be suppressed.

[0119] Furthermore, the housing 2 is not limited to the structure described above. The housing body 50 may not be composed of two parts: the frame 51 and the outer casing 52. The housing body 50 may be configured as a single part, or it may be made into a structure composed of three or more parts. In short, as long as a membrane 60 is provided on the housing body 50 with the opening 53, the opening 53 can be sealed with the membrane 60. If so, the membrane 60 is easier to fix.

[0120] Alternatively, the sensor element 1 can be installed in devices such as endoscopes or robotic arms. In this case, the housing of the device in which the sensor element 1 is installed can also be used as the housing body 50 or the outer casing 52. That is, as long as an opening 53 is formed on the housing of the device, the opening 53 can be sealed with a membrane 60.

[0121] Furthermore, the housing 2 may not have a housing body 50. In a configuration that prevents liquids and dust from entering the gaps in the mechanical structure of the sensor element 1, the membrane 60 can be provided in a manner that at least covers the sensing surface or contact end 21. For example, it may be configured such that the entire sensor element 1 is wrapped with the membrane 60.

[0122] (Tactile Measurement Methods)

[0123] Next, the tactile measurement method using the tactile sensor AA will be explained.

[0124] The operation of the tactile sensor AA in tactile measurement is basically the same as that of using sensor element 1 alone. That is, as... Figure 14 As shown, the tactile sensor AA is pushed against the object being measured O while being swept. Here, the sensing surface of the sensor element 1 contacts the object being measured O via the membrane 60.

[0125] Since the outer casing 52 covers a portion of the membrane 60, the area of ​​the membrane 60 in contact with the object being measured, O, is correspondingly reduced. That is, the membrane 60 only contacts the object being measured, O, on the portion corresponding to and around the opening 53. Furthermore, since the object being measured, O, also contacts the outer casing 52, the pushing force of the tactile sensor AA is not only applied to the membrane 60 but is also dispersed by the outer casing 52. Therefore, the possibility of the membrane 60 breaking due to friction with the object being measured, O, can be suppressed.

[0126] If the tactile sensor AA is pushed against the object being measured O while being swept, the contacts 20A to 20F will displace in the x-axis and z-axis directions. Based on this displacement, the surface shape, friction, etc., of the object being measured O can be measured. The principle is the same as when sensor element 1 is used alone.

[0127] Compared to the case where sensor element 1 is used alone, the tactile sensor AA differs in that the contacts 20A-20F indirectly contact the object being measured O via the membrane 60. Here, if the contacts 20A-20F are not fixed to the membrane 60, especially under tangential force, the membrane 60 only shifts laterally, and the contacts 20A-20F do not move. However, in this embodiment, since the contact end 21 is fixed to the inner surface of the membrane 60, the contacts 20A-20F move in sync with the movement of the membrane 60, which is in direct contact with the object being measured O. Therefore, the decrease in the spatial resolution and sensitivity of sensor element 1 can be suppressed.

[0128] If the tactile sensor AA is pushed against the object O being measured while scanning, then as follows: Figure 15 As shown, there is a case where the tactile sensor AA is tilted forward in the sweeping direction. In this case, if the adhesive surface 54 of the frame 51 is a plane coplanar with the opening 53, the end of the frame 51 in the sweeping direction will bite into the object O being measured. As a result, the portion of the membrane 60 corresponding to the end of the frame 51 in the sweeping direction may rupture due to strong friction.

[0129] In this respect, the bonding surface 54 of the frame 51 in this embodiment is a frustum-shaped square pyramid. That is, the end of the frame 51 in the sweeping direction is an inclined surface. This inclined surface is inclined in such a way that it moves away from the measuring object O as it moves away from the opening 53 in the sweeping direction. Therefore, even if the tactile sensor AA tilts forward during sweeping, it is not easy to exert a strong force on a part of the membrane 60, and the rupture of the membrane 60 can be suppressed.

[0130] As described above, the tactile sensor AA combines the high spatial resolution and sensitivity of sensor element 1 with waterproofing and dustproofing. Therefore, it can measure tactile sensations in environments where sweat or blood may adhere, such as in the medical, care, and beauty / health fields. Furthermore, it can also measure tactile sensations in industrial applications where dust or droplets may adhere.

[0131] [Second Implementation]

[0132] The structure of the sensor element is not limited to the embodiments described above. For example, it can also use... Figure 16 Sensor element 3 with the structure shown.

[0133] The sensor element 3 mainly includes a base 10, a contact 20, and a diaphragm 30. The base 10 has a cylindrical space. The lower opening of this space is blocked by the diaphragm 30. A cylindrical contact 20 is erected in the center of the diaphragm 30. That is, the contact 20 is located in the center of the cylindrical space in the base 10. Furthermore, the diaphragm 30 is a support that supports the contact 20 relative to the base 10.

[0134] The sensor element 3 uses its upper surface as a sensing surface to withstand the force from the object being measured. Therefore, the upper surface of the base 10 is the reference surface 14, and the upper surface of the contact 20 is the contact end 21.

[0135] A gap is provided between the base 10 and the contact 20, allowing the contact 20 to swing. The diaphragm 30 is strained by the contact 20 due to external forces, such as tilting in the x-axis direction, y-axis direction, or displacement in the z-axis direction. In order to detect such deformation of the diaphragm 30, a displacement detector is formed on the diaphragm 30.

[0136] like Figure 17 As shown, in this embodiment, the tactile sensor BB has its sensor element 3 housed in a housing 4. The housing 4 consists of a housing body 50 having an opening 53 and a membrane 60 that seals the opening 53. The sensing surface of the sensor element 3 is in close contact with the inner surface of the membrane 60. The base 10 is fixed relative to the housing body 50, and the contact end 21 is fixed to the inner surface of the membrane 60.

[0137] When measuring touch with the touch sensor BB, the touch sensor BB is pushed against the object being measured O while being swept. Here, the sensing surface of the sensor element 3 contacts the object being measured O via the membrane 60.

[0138] If the tactile sensor BB is pushed against the object being measured O while being swept, the contact head 20 will displace in the x-axis, y-axis, and z-axis directions. Based on this displacement, the surface shape, friction, and other properties of the object being measured O can be measured.

[0139] Example

[0140] Next, an embodiment will be described.

[0141] A tactile sensor with the same structure as the tactile sensor AA in the first embodiment was fabricated. The sensor element was formed by processing a semiconductor substrate. In addition, the housing body was fabricated by 3D printing. As the membrane, a medical polyurethane membrane with a thickness of 8 μm (YUKI PERME-ROLLLite, a thin membrane dressing manufactured by Nitto Denko Co., Ltd.) was used.

[0142] The spring constants of the contact were measured in both the diaphragm-covered and non-diaphragm-covered conditions, along the z-axis and x-axis. A micromechanical measuring instrument (Femtotools FT-MTA03) with a force resolution range of nN was used for the measurements. The measuring probe was placed against the front end of the sensor element's contact or the front end of the contact covered by the diaphragm. The spring constant in the z-axis direction was determined by precisely measuring the load change (change in the reaction force from the contact support) under continuously small displacements applied to the sensor element along the z-axis direction. Similarly, the spring constant in the x-axis direction was determined by continuously applying small displacements to the sensor element along the x-axis direction with the measuring probe and measuring the load change. The results were expressed as follows: Figure 18 (A) and Figure 18 In (B). Figure 18 The horizontal axis of the curve (A) is the displacement of the contact in the z-axis direction, and the vertical axis is the reaction force of the contact. Figure 18 The horizontal axis of the curve (B) represents the displacement of the contact in the x-axis direction, and the vertical axis represents the reaction force of the contact.

[0143] The spring constant in the z-axis direction is 49.2 N / m without a membrane and 59.6 N / m with a membrane. The spring constant in the x-axis direction is 205.6 N / m without a membrane and 212.1 N / m with a membrane. Thus, by adding a membrane, the spring constant in the z-axis direction increases by 21.1%, and the spring constant in the x-axis direction increases by 3.2%. This is because the membrane, which is in close contact with the contact, is elastic.

[0144] If the spring constant of the contact increases, the displacement of the contact corresponding to the input decreases. This means that if a diaphragm is used, the sensitivity of the sensor element decreases proportionally. However, according to... Figure 18 (A) and Figure 18 The curve (B) confirms that even with the membrane in place, the linearity of the response can be adequately maintained.

[0145] Next, tactile measurements were performed using a roughness standard sheet. The roughness standard sheet used was a surface shape with triangular bumps and depressions continuously spaced at a specified interval. The tactile sensor was swept across the bumps and depressions to obtain a measurement signal.

[0146] exist Figure 19 The figure represents the case of measuring a roughness standard with a pitch of approximately 250 μm. No effect of the presence or absence of a film was confirmed in the signal of unevenness. On the other hand, regarding the signal of friction, the waveform becomes smoother with a film compared to the case without one. This is likely because the film buffers the contact between the contactor and the unevenness of the roughness standard.

[0147] exist Figure 20The image shows the results of measuring a roughness standard sheet with a 32 μm pitch. Compared to the uncoated case, a decrease in the amplitude of the unevenness was confirmed in the coated case. However, unevenness could still be identified. Therefore, it was confirmed that a spatial resolution of less than 50 μm can be maintained even with the coating.

[0148] As described above, it can be said that the mechanical properties of the sensor element change by setting a membrane. However, compared to the tip of a stiffer contact, a flexible membrane is closer to human skin. Therefore, it can also be considered that setting a membrane allows for the measurement of touch under conditions closer to human touch.

[0149] Next, the sensitivity of the tactile sensors in the air and water was measured. Figure 21 (A) is a graph showing the sensitivity of the measurement to the force exerted on the object in the air along the z-axis.

[0150] Figure 21 (B) is a graph showing the sensitivity of the measurement to the force exerted on the object in the z-axis direction in water. Figure 21 (A) and Figure 21 The horizontal axis of the curve (B) represents the displacement of the contact in the z-axis direction, and the vertical axis represents the rate of change of resistance measured by the vertical displacement detector. The sensitivity is determined based on the slope of each curve.

[0151] The sensitivity in air is 739 ppm / μm, and the sensitivity in water is 735 ppm / μm. This confirms that the sensitivity remains unchanged in both air and water. Furthermore, even in measurements taken in water, there was no water intrusion into the sensor element, and no short circuits occurred in the detection circuit.

[0152] Next, the coefficient of friction was determined by sweeping a tactile sensor across the surface of a flat glass plate in air, water, and glycerin. The results were then expressed as follows: Figure 22 In the middle. By Figure 22 It is evident that the coefficient of friction in glycerin is lower than in other cases. This is due to glycerin's role as a lubricant. This confirms that frictional forces in liquids can also be measured accurately.

[0153] Next, the surface of the simulated internal organs used in surgical training was measured using a tactile sensor. The simulated internal organs contained more than 70% water and had fine irregularities on their surface. In addition, simulated blood vessels, which were harder than the surrounding tissue, were embedded in a portion of the simulated internal organ. The tactile sensation was measured by sweeping the tactile sensor across the simulated blood vessels.

[0154] Express its results in Figure 23In this study, it was confirmed that a tactile sensor can detect the minute irregularities and friction on the surface of a simulated internal organ with high resolution. Furthermore, based on the waveforms of the irregularities and friction, the location of simulated blood vessels embedded within the simulated internal organ can be identified. This confirms that a tactile sensor can measure the tactile sensation of a wet object and can also be applied to medical purposes.

[0155] Label Explanation

[0156] AA and BB tactile sensors

[0157] 1, 3 Sensor Components

[0158] 2, 4 shell

[0159] 10. Base

[0160] 20A~20F contacts

[0161] 21 contact terminals

[0162] 30A~30F support body

[0163] 40A~40F Displacement Detector

[0164] 50. Shell body

[0165] 51 Framework

[0166] 52 outer body

[0167] 53 Opening

[0168] 54 Adhesive Surface

[0169] 60 membrane

Claims

1. A tactile sensor characterized by comprising: a sensor element; and a housing that houses the sensor element. The sensor element comprises: a base; a contact having a contact end; a support body that supports the contact so as to be displaceable with respect to the base; and a displacement detector that detects displacement of the contact with respect to the base. The housing comprises a flexible film that covers at least the contact end in the sensor element. The contact end is fixed to an inner surface of the film so that the contact moves in response to movement of the film.

2. The tactile sensor according to claim 1, characterized in that the film has an adhesive layer on the inner surface, and the contact end is adhered to the film by the adhesive layer.

3. The tactile sensor according to claim 1, characterized in that the contact end has a spike that is embedded in the film.

4. The tactile sensor according to any one of claims 1 to 3, characterized in that the housing further comprises a housing body having an opening portion, the opening portion is blocked by the film, the contact end is disposed in the opening portion, and the base is fixed with respect to the housing body.

5. The tactile sensor according to claim 4, characterized in that the housing body comprises: a frame having the opening portion, the film being adhered to a sticking surface on which the opening portion is located; and an outer body that covers a portion of the film other than a portion corresponding to the opening portion.

6. The tactile sensor according to claim 5, characterized in that an end portion of the opening portion in a sweeping direction is semicircular or semioval.

7. The tactile sensor according to claim 5, characterized in that the frame has an inclined surface on an end portion in the sweeping direction. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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