JP5013507B2 - Tactile sensor using reflection image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tactile sensor allowing high-resolution sensing by making the best use of the resolution of a camera. <P>SOLUTION: The tactile sensor comprises elastically deformable transparent silicone rubber 1, an image pattern 2 as a real image, and the camera 3. The interface between the transparent silicone rubber 1 and the air forms a reflecting surface 4 owing to a refractive index distribution, thereby allowing the image of the image pattern 2 to be reflected by the reflecting surface 4 and to enter the camera 3. The deformation of the flexible reflecting surface 4 caused by an object deforming the transparent silicone rubber 1 is measured by observing the distortion of a reflected image. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

The present invention relates to a tactile sensor using a reflected image.

In recent years, with the development of robotics, many tactile sensors have been developed. Conventional tactile sensors include a sensor that measures a contact state and a sensor that measures a force distribution. As tactile sensors that measure force, there are 6-axis force sensors that measure force at one point, sensors that measure contact state, and tactile sensors that measure force distribution. In many distributed force sensors, the number of sensor units and the number of wires associated with the units are problematic. In addition, since small sensors are distributed individually, each sensor unit itself is arranged at a location close to the measurement surface. Therefore, the sensor itself is subjected to stress as the measurement is repeated, and deterioration is unavoidable.

Further, several researches have been made as optical distributed tactile sensors at the research level (Patent Document 1). These sensors are good examples where the unit and wiring can be eliminated from the measurement surface by consolidating the sensing part into the camera. However, since a marker composed of a point array or a grid array is used as a measurement spot and sensing is based on these markers, it cannot be said that the resolution of the camera is sufficiently utilized.
International Publication WO02 / 18893 A1

An object of the present invention is to provide a tactile sensor that enables high-resolution sensing that fully utilizes the resolution of a camera.

Another object of the present invention is to provide a tactile sensor having fracture resistance.

Another object of the present invention is to provide a tactile sensor that can reduce wiring.

Another object of the present invention is to provide a tactile sensor capable of simultaneously measuring a contact state and a shape distribution (force distribution).

The tactile sensor of the present invention comprises a sensor body having a deformable reflective surface, an image pattern, and an image acquisition element that acquires a reflected image of the image pattern on the reflective surface using an optical lever. A tactile sensor using an image. The “deformable reflecting surface” means that the reflecting surface is deformed when the object comes into contact with the sensor body. In the sense that the object is deformed by contacting the sensor body, the deformable reflecting surface is a flexible reflecting surface. The deformable reflecting surface is preferably an elastically deformable reflecting surface. If only one measurement is required, the deformable reflecting surface may be plastically deformed. Further, the deformable reflecting surface is preferably formed on the surface (interface) of the sensor body. By the image acquisition element, the reflection image before the object contacts the sensor body and the reflection image when the object contacts the sensor body by acquiring the reflection image when the object contacts the sensor body. Can be obtained.

The tactile sensor device of the present invention includes a sensor main body having a deformable reflection surface, an image pattern, an image acquisition element that acquires a reflection image of the image pattern on the reflection surface using an optical lever, and the image acquisition. from the reflected image obtained by the element to obtain a deformation of the reflected image when the object is in contact with the contacted surface of the sensor body, and a reflecting surface reconstruction means for calculating the deformation of the reflecting surface from the deformation of the reflected image, A tactile sensor device using a reflected image. The reflecting surface reconstruction means can be configured from a computer.

In one preferred embodiment, the sensor body is transparent, and the light beam that forms the reflected image propagates through the sensor body. That is, light rays incident on the reflection surface from the image pattern and light rays reflected from the reflection surface toward the image acquisition element propagate in the medium of the sensor body.

In one preferred embodiment, the reflective surface is formed by an interface of the sensor body, and the material of the sensor body is selected from materials having a refractive index such that the interface forms a reflective surface. More specifically, the material of the sensor body is selected so that the refractive index of the medium of the sensor body is larger than the refractive index of the medium that forms an interface with the surface of the sensor body.

In one preferable aspect, the sensor body includes a transparent elastic body at least in part, and the deformable reflecting surface is formed by an interface of the transparent elastic body. In one aspect, the whole sensor main body is comprised from the transparent elastic body. Silicone rubber is illustrated as a transparent elastic body.

In one aspect, a part or all of the surface of the sensor body is formed from a film, and the fluid is filled inside the film, and the deformable reflective surface is formed from the film. ing. In one embodiment, the sensor body is composed of a membrane and a fluid sealed in the membrane.

In one aspect, the sensor body has a deformable plate-like body, and the deformable reflecting surface is formed from the surface of the plate-like body.

In one embodiment, the image pattern and / or the image acquisition element are located outside the sensor body. Preferably, both the image pattern and the image acquisition element are located outside the sensor body. In one aspect, the transparent sensor body includes a plurality of surfaces, at least one of the plurality of surfaces forms the deformable reflective surface, and at least one surface of the plurality of surfaces is A pattern surface on which light rays from the image pattern are incident is formed, and at least one of the plurality of surfaces forms a photographing surface from which reflected light from the reflecting surface is emitted. The image pattern is disposed facing or close to the pattern surface, and the image acquisition element is disposed facing or close to the imaging surface. The image pattern and the image acquisition unit may be in contact with or attached to the pattern surface and the imaging surface, respectively, or may be separated from the pattern surface and the imaging surface. Furthermore, in one preferable aspect, the transparent sensor main body includes a pattern surface group composed of a plurality of pattern surfaces parallel to each other, and a photographing surface group composed of a plurality of photographing surfaces parallel to each other, The pattern surface and each imaging surface are alternately arranged.

In one embodiment, the image pattern and / or the image acquisition element is located inside the sensor body. FIG. 15 illustrates a tactile sensor in which an image pattern and an image acquisition element are located inside the sensor body.

Preferably, the reflection surface is a contacted surface (sensor surface) with which an object contacts. That is, when the target object comes into contact with the deformable reflection surface, the reflection surface is deformed and the reflected image is deformed.

In one embodiment, the transparent sensor body constitutes a prism. That is, at least one surface of the prism forms a reflecting surface, at least one surface forms a pattern surface, and at least one surface forms a photographing surface.

In one embodiment, the image pattern is formed by a light emitting element. Examples of the light emitting element include an LED and a laser. In one embodiment, the image pattern is generated by a liquid crystal display. In one embodiment, the image pattern is dynamically variable.

In one aspect, the image acquisition element is a camera. In one embodiment, the image acquisition element includes a solid-state image sensor. Examples of the solid-state imaging device include a CCD and a CMOS device. In one embodiment, the image acquisition element comprises a PD (Photodetector).

According to the present invention, it is possible to configure a high-resolution tactile sensor using an optical lever by making use of the reflection characteristics on the reflection surface of the sensor body, and sensing that makes full use of the resolution of the camera is possible.

The tactile sensor of the present invention includes a sensor body having a reflecting surface (preferably including a transparent elastic body at least in part), an image pattern, and an image acquisition element. The image pattern and the image acquisition element, which are constituent elements of the sensor, can be arranged outside the main body with which the object comes into contact. Therefore, according to the present invention, it is possible to provide a sensor in which the image pattern and the image acquisition element are hardly affected by the contact of the object and are resistant to destruction. Further, even when any of the constituent elements constituting the tactile sensor is deteriorated, it can be easily replaced. Further, since wiring only needs to be performed for the image pattern and the image acquisition element, it is possible to save wiring compared to a conventional sensor that needs to be wired on the main body that the object contacts.

According to the present invention, by arranging the image pattern and the image acquisition element outside, the selection of the configuration of the components of the sensor is flexible. Due to the simple combination of the light beam and the deformable reflecting surface, the pattern surface on which the incident light of the image pattern is incident and the imaging surface on which the reflected light from the reflecting surface is emitted can be appropriately selected. For example, it is conceivable to arrange a laser beam or light emission diode (LED) on the pattern surface, a liquid crystal display, and a photo detector (PD) or camera on the imaging surface. The processing speed can be increased by replacing the image pattern and camera with LED and PD.

A tactile sensor capable of feedback measurement can be provided by making the pattern dynamically changeable. The dynamic pattern can be generated by a liquid crystal display in one embodiment. Further, the sensor body can be made thin by configuring the pattern surface and the imaging surface of the sensor body from a plurality of surface groups and arranging the pattern surfaces and the imaging surfaces alternately.

According to the present invention, it is possible to configure a tactile sensor that can simultaneously measure a contact state and a shape distribution (force distribution) by a reflecting surface using a refractive index distribution. It is also possible to calculate the contact pressure from the shape distribution based on the elasticity theory.

The present invention can provide a tactile sensor capable of measuring a non-contact state by using a transparent elastic body. Also, it can be combined with other optical devices. For example, by using an optical projector together, a user interface for tactile input visual output can be configured.

[A] Configuration of the Present Invention FIG. 1 shows one embodiment of a tactile sensor of the present invention. The tactile sensor according to the present invention includes a transparent elastic body 1, an image pattern 2 as a real image, and a camera 3. Based on the refractive index distribution at the interface between the surface of the transparent elastic body serving as the sensor surface and air, the surface of the transparent elastic body constitutes a flexible reflecting surface (mirror surface) 4. When the object 5 comes into contact with the flexible reflecting surface 4 and is deformed, the reflecting surface 4 is distorted. The deformation of the reflecting surface 4 is measured by observing the image reflected on the reflecting surface 4 from the camera 3. The tactile sensor of the present invention uses an optical lever principle and a flexible reflecting surface in combination. The optical lever is a technique for enlarging displacement by utilizing the characteristic of reflection. In the present invention, a tactile sensor capable of accurately detecting the deformation of the reflecting surface by using an optical lever and sufficiently utilizing the resolution of the camera is configured.

The configuration of the tactile sensor will be described more specifically. In FIG. 1, the main body of the tactile sensor is composed of a transparent elastic body 1, and the transparent elastic body 1 forms a prism having three surfaces: a first surface 10, a second surface 11, and a third surface 12. is doing. The first surface 10, the second surface 11, and the third surface 12 form a plane when no external force acts on the transparent elastic body 1. The second surface 11 and the third surface 12 extend so that one end edge of the second surface 11 and one end edge of the third surface 12 intersect at a right angle. It extends so that an end edge and the other end edge of the 3rd surface 12 may be connected. Incident light that is incident on the transparent elastic body 1 through the second surface 11 is totally reflected by the first surface 10 that forms the reflective surface 4 and is emitted from the third surface 12 as reflected light. . The image pattern 2 is disposed in the vicinity of the second surface 11. The image pattern 2 may be in contact with the second surface 11, or the image pattern 2 may be opposed to the second surface 11 with a gap. The camera 3 is disposed to face the third surface 12.

In one preferred embodiment, transparent silicone rubber is exemplified as the transparent elastic body 1, and the flexible reflective surface 4 is formed of silicone rubber. Therefore, from the refractive index distribution at the boundary where the silicone rubber is in contact with air, this interface has reflection characteristics as a reflection surface. By using this specular reflection characteristic, a distributed tactile sensor having a flexible reflecting surface 4 is configured.

Although the silicone rubber as the transparent elastic body 1 has been described, other materials that can form the transparent elastic body 1 include optically transparent materials such as glass and acrylic. Moreover, the external world which forms an interface between the surface which forms the reflective surface 4 of the transparent elastic body 1 is not limited to an air atmosphere, Gas other than air, a liquid, and a vacuum can be considered. It is easily understood by those skilled in the art that the refractive index distribution in the vicinity of the interface is important for the interface to function as the reflecting surface (mirror surface) 4. If the refractive index of the transparent elastic body 1 is larger than the refractive index of the space forming the interface with the transparent elastic body 1, the interface can form the reflecting surface 4. Therefore, the surface of the transparent elastic body 1 is made to function as the reflecting surface 4 by appropriately selecting the refractive index of the space forming the interface between the material forming the transparent elastic body 1 and the surface of the transparent elastic body 1. be able to. For example, if the air layer is changed to a layer made of another substance, the conditions causing the reflection also change. When silicone rubber is employed as the transparent elastic body 1, necessary conditions include those having a refractive index smaller than that of silicone rubber. Here, the refractive index of air is 1.000292, and the silicone rubber is about 1.5. The vacuum is 1, many gases are close to 1, and the surface of the transparent elastic body 1 can form the reflecting surface 4. Although the refractive index of water is 1.33 and the condition is worse than that of air, the reflected image can be observed by appropriately selecting the orientation of the camera and the angle of incident light from the image pattern.

[B] Principle of the Invention The optical lever plays an important role in the sensor according to the present invention. The point is how to create a flexible reflecting surface to realize this optical lever. By using the property of the flexible reflecting surface that allows different reflected images to be obtained before and after the deformation of the reflecting surface itself, the deformation of the reflecting surface itself is obtained by measuring its displacement using geometric optics. Hereinafter, each of these elements will be described in detail.

[B-1] The reflection condition light lever method refers to a method of irradiating the tip of a cantilever or the like with a light source such as a laser to increase the displacement of the reflecting surface by utilizing the characteristic of reflection. As a flexible reflective surface, one preferred embodiment uses transparent silicone rubber. When considering the boundary between the silicone rubber and air, such as in FIG. 3, the respective refractive index n _s, a n _a, the incident angle, the refraction angle [Phi _s, by placing the [Phi _a, boundaries silicone rubber is in contact with air From the refractive index distribution in FIG. 5, total reflection occurs when Expression (1) is satisfied, and this interface has reflection characteristics as a reflection surface. By using this specular reflection characteristic, a sensor having a flexible reflection surface is configured.

[B-2] Deformation of Reflected Image Among those using a camera as an optical sensor, there is one that captures deformation by tracking a marker (Patent Document 1). However, the resolution of the sensor is also limited by the resolution of the marker. On the other hand, the tactile sensor according to the present invention can use the resolution of the camera to the maximum extent by using a combination of a light reflector and a flexible reflecting surface.

As shown in FIG. 1, the image pattern 2, the camera 3, and the transparent silicone rubber as the transparent elastic body 1 are arranged so that the scattered light from the image pattern 2 is reflected on the first surface 10 (reflection surface 4) of the transparent elastic body 1. And is imaged on the camera 3. At this time, when the contact object 5 touches the transparent silicone rubber, the first surface 10 (the reflection surface 4) of the transparent elastic body 1 is deformed. When the reflecting surface 4 is deformed, the reflected image of the image pattern 2 is deformed. By solving the inverse problem from this deformation, the deformation of the reflecting surface 4 itself is measured. Thereby, all of the reflected images have information, and the resolution of the camera can be utilized to the maximum.

[B-3] Geometrical optics As shown in FIG. 3, when a pattern to be imaged is arranged in a plane (P ₀ P ₁ P ₂ ), the surface having this pattern is named a pattern surface (image pattern). The incident light from the second surface 11 forms a pattern surface in the tactile sensor of FIG. The angle between the pattern surface and the reflection surface is α ₀ , and the angle between the imaging surface and the reflection surface is β ₀ .

It is assumed that Q ₁ , which is a plane P ₀ R ₀ before the deformation, is subducted by d _{1 at} a distance of ₁ from P ₀ after the deformation and is inclined by θ ₁ . Similarly _{P 0} Q2 at a distance of l + .DELTA.l sinks d + [Delta] d from the inclined theta _2. At this time, considering the case where an image is projected as P ₁ → Q ₁ → R ₁ , P ₂ → Q ₂ → R ₂ , the light rays incident on the camera are α ₁ and α _{2 on} the pattern surface, β _{1 on the} imaging surface, Let β _{2 be} inclined. When the inclination of the reflecting surface in Q ₁ and Q ₂ changes Δθ continuously as θ ₁ → θ ₂ , the height displacement Δd represented by Q ₁ and Q _k is
It is represented by

Also, from the symmetry of the incident angle and reflection angle on the reflection surface,
Next, m = P ₀ P ₁ and w = R ₀ R ₁ are represented by Δl.
It can be expressed.

[B-4] Reconstruction of Reflecting Surface The amount that can be measured by the tactile sensor of the present invention is m, w, β ₁ , β ₂ , and the known amounts are L ₀ , α ₀ , β ₀ . The quantity to be obtained is the distribution of θ and d. From equation (2), if Δθ and Δl are known, Δd can be constructed, and if Δθ and Δd are known, θ and d can be reconstructed.

here,
And Δα → 0, and Δα from the second-order Taylor expansion,
Also, from equations (3), (5), (6)
It becomes. In the formula (2), the Q ₁ and n-th feature point, when the n-th [Delta] d represents the [Delta] d _n, from the continuity of the boundary surface,
Assuming As a result, equation (2) can be expressed as follows.
Since the l = 0 and l = L ₀ at d = 0 can be assumed, seeking l _n from equation (6), can be determined theta _n from (7). Δθ _n is obtained from the obtained θ _n and Δd _{n + 1} is calculated by using equation (9). By gradually repeating this, the distributions θ _n and d _n of θ and d are obtained.

[C] Simulation Based on the geometric optics described above, the accuracy is confirmed by simulation. The deformed shape is about 13 [pixel] on the vertical axis with respect to 1637 [pixel] on the horizontal axis (FIG. 4).

Assuming that a curved surface as shown in FIG. 4 is vertically inverted as a reflecting surface, α ₀ = β ₀ = π / 4, camera center at infinity, β ₁ = β ₂ = β ₀ , L ₀ = 1637 [pixel ] At this time, the discrete points P _n (n = 0... N) on the pattern surface in the axis passing through the center of deformation are imaging surfaces (surfaces from which the reflected light from the image pattern is emitted) by the reflecting surfaces. A point R _n (n = 0... N) appearing on the third surface 12) of the tactile sensor is calculated as a forward problem. By using the thus calculated P _n, R _n, the angular distribution theta _n, the depth distribution d _n Formula (7), solving the inverse problem as an approximate solution using (9). The calculation results are shown in FIGS.

The solid line is the original reflecting surface shape,-is the sum of Δl and Δd added from 1 = 0 in ascending series, and Δ is the sum of l = L ₀ and descending series. FIG. 5 shows that the distribution of θ can be traced almost accurately. In addition, the approximate shape of the position can be traced. Note that the error rate (error / true value) is kept at about 1% over the entire area. In addition, even if there is a non-differentiable point on the reflecting surface, it can be measured without any problem.

[D] Implementation Based on the above simulation, an actual system is constructed and the operation is confirmed.
[D-1] Addition polymerization type silicone (Shin-Etsu Chemical: transparent silicone RTV rubber) is used as silicone rubber and lattice-patterned transparent silicone rubber. The shape of the transparent silicone rubber is the same as that shown in FIG. As the image pattern, an image pattern printed on paper and pasted on a pattern surface (a surface on which incident light from the image pattern is incident, the second surface 11 in FIG. 1) is used. In this way, a tactile sensor having a flexible reflective surface is created. Install and fix a camera that reflects the created flexible reflecting surface.

[D-2] Measurement in an actual environment is performed using an experimentally mounted sensor. As shown in FIG. 7A and FIG. 7B, the tip of the pencil was applied to the sensor surface, and the state where it was pushed in by about 0.2 [mm] was measured. The image acquisition element used in the experiment is a CCD camera.

A grid pattern was used as the image pattern. At this time, the lattice points in a single vertical column at the center were matched as feature points, and the shape was restored based on a theoretical formula. FIG. 8 shows the average of the ascending sequence and the descending sequence. The grid pattern used this time is 2.5 [mm] wide, the acquired image size is 625 x 392 [pixel], and the number of grids in the image is 16 in length, so 1 [pixel] can be regarded as 0.1 [mm] The peak value of the average series shows a value close to the true value.

In the ascending series, l = 0 and L ₀ , and in the descending series, l = 0 and L ₀ are close to true values. The measured error can be avoided by repeated calculation.

[E] Features of the Present Invention Conventionally, a tactile sensor that has been used in the past often requires a complicated configuration such as a wiring problem or the arrangement of the sensor itself. If the information that can be sensed as a tactile sensor is also a force sensor, only force is measured. , And so on. The present invention is characterized by being able to sense a large amount of information and highly accurate information while using a very simple configuration of a transparent elastic body, an image pattern, and a camera. Hereinafter, the features of the present invention will be described in more detail.

[E-1] Fracture resistance In a conventional tactile sensor, elements used for sensing must be arranged at tactile measurement points, and deterioration of the sensor itself is unavoidable due to repeated measurement. On the other hand, in the present invention, since only the transparent elastic body is present at the tactile measurement point, it is much stronger against deterioration. Further, since the sensor element itself that converts a physical signal into an electrical signal does not exist at the measurement point, even if the measurement point portion is damaged, the transparent elastic body at the measurement point portion can be easily and inexpensively replaced.

[E-2] Reduced wiring Since all sensing is performed by the image pattern and the camera, the entire sensor surface can be sensed only by wiring to the image pattern and the camera.

[E-3] A light lever is a technique for measuring displacement by enlarging displacement by using a reflection surface and a light beam. In the present invention, a reflection surface is formed by forming a flexible reflection surface. It became possible to measure the distortion of the light using an optical lever. The distortion is magnified by the optical lever, and a sensor having high resolution can be configured.

[E-4] Measurement of Contact State and Shape Distribution In the present invention, the reflection surface is configured by utilizing a reflection phenomenon caused by the refractive index distribution at the interface between the transparent elastic body and air (for example). Therefore, the behavior changes between a portion that satisfies the condition of the reflecting surface and a portion that does not. That is, as shown in FIG. 9, the interface acts as a reflecting surface around the contact area, the deformation due to contact is measured from the distortion of the virtual image, and the shape distribution is calculated from this information. At the same time, the contact state between the contact object itself and the sensor is observed as a real image in a portion that does not satisfy the condition. Taking a case where a finger is pressed as an example, this is equivalent to measuring at the periphery what kind of force distribution is applied by the finger and causing deformation, and simultaneously measuring the shape of the fingerprint in contact with the finger.

[E-5] Utilization of camera resolution In a tactile sensor using a conventional camera (see Patent Document 1), a dot sequence or a grid sequence is mainly arranged as a marker inside an elastic body, and the movement of the marker is controlled by the camera. Sensing using. For this reason, the information used for sensing is limited by point arrays and grid arrays, and it cannot be said that all the resolution of the camera itself is utilized. On the other hand, in the present invention, information can be taken from all the images entering the camera by using the reflected image. This constitutes a sensor that makes the most of the resolution of the camera.

[E-6] The feedback measurement image pattern based on the dynamic pattern is not limited to a static image pattern, and may be a dynamically variable image pattern. For example, it is possible to perform measurement using feedback by generating an image pattern using a liquid crystal display (LCD). That is, it is possible to perform measurement using the null method by displaying the original image pattern so as to eliminate the distortion of the virtual image of the image pattern accompanying the deformation of the reflecting surface.

[E-7] Thinning and high-speed processing In the present invention, a sensor is configured by acquiring a reflection image at the interface between the transparent elastic body and air. Similar interfaces exist in the path from the pattern and the path to the camera. Here, in order not to cause reflection, it is necessary to configure each interface in parallel with the camera and the pattern. For this reason, the main body of the tactile sensor of the present invention has a prism shape, but this prism shape can be made thin. FIG. 10 illustrates an example of a thin sensor body. In FIG. 10, the sensor body has a plate-like transparent elastic body 1 whose one surface is the first surface 10 constituting the flexible reflecting surface 4, one surface having a plurality of second surfaces 11 ′, and a plurality of surfaces. A transparent plate-like body 1 ′ configured by alternately arranging third surfaces 12 ′, and the other surface of the plate-like transparent elastic body 1 and the other side of the transparent plate-like body 1 ′. It is comprised by sticking a surface. A group of a plurality of second surfaces 11 ′ constitutes a surface on which light rays from the image pattern 2 are incident, and a group of a plurality of third surfaces 12 ′ constitutes a surface from which reflected light from the reflecting surface 4 is emitted. . The second surface 11 and the third surface 12 in FIG. 1 are each composed of a group of a plurality of second surfaces 11 ′ and a group of a plurality of third surfaces 12 ′, thereby reducing the thickness of the sensor body. Making it possible. Each 2nd surface 11 'which comprises the group of several 2nd surface 11' is extended at the same angle. Each third surface 12 'constituting a group of a plurality of third surfaces 12' extends at the same angle. The second surface 11 ′ and the third surface ′ 12 extend in directions orthogonal to each other in the illustrated example.

FIG. 11 illustrates an example of an image pattern and an image acquisition element employed in the tactile sensor shown in FIG. In FIG. 10, a group of a plurality of second surfaces 11 ′ constitutes the pattern surface, and a group of the plurality of third surfaces 12 ′ constitutes the imaging surface. A surface from which the reflected light from the reflecting surface 4 is emitted is configured. As shown in FIG. 11, a strip-shaped light emitting element 2 ′ is provided in contact with or close to the second surface 11 ′, and an image pattern is formed from the plurality of strip-shaped light emitting elements 2 ′. Examples of the strip-shaped light emitting element 2 ′ include a strip-shaped LCD and a light emitting element such as an LED (Light Emission Diode). In the tactile sensor of FIG. 11, an image acquisition element 3 ′ is provided in contact with or close to the third surface 12 ′. In FIG. 11, as the image acquisition element 3 ′ employed instead of the camera, a line CCD (Charge Coupled Device) or PD (Photo
Detector) is exemplified. Also, since LEDs and PDs have high resolution in the time direction, using them makes it possible to greatly speed up the sensing process.

[E-8] The non-contact observation tactile sensor is a sensor that measures a contact state. However, the tactile sensor of the present invention enables non-contact observation by using a camera and a transparent sensor body. Therefore, the tactile sensor of the present invention can observe the object through the non-contact state and the contact state. 12 and 13 show examples of non-contact observation. In FIG. 12, the non-contact state is directly observed. In FIG. 13, a non-contact state is observed using reflection on a pattern surface (a surface on which incident light from an image pattern is incident, the second surface 11 in FIG. 1).

[E-9] Combined use with visual display The tactile sensor of the present invention is a sensor having a high degree of optical freedom by using a transparent elastic body. That is, various combinations with other optical devices are possible. As an example, FIG. 14 shows a configuration combined with a visual display. A cloth-like screen material is installed on the sensor surface, and light is projected from the back by a projector. By projecting from the back side, there is no problem such as shadowing of one's finger at the time of tactile input. Since the screen material is lightweight and the contact is discrete, it does not significantly affect deformation sensing. As a result, it can also be used as an interactive human interface device having tactile input and visual output.

The present invention can be industrially used as a tactile sensor. Specifically, a tactile sensor in the robot industry, a tactile sensor that quantifies the texture of a product such as clothing, and a tactile sensor as a user interface are exemplified.

It is the schematic of the tactile sensor which concerns on this invention. It is a figure which shows Snell's law. It is a figure which shows the geometrical optics in a sensor cross section. It is a figure which shows the acicular deformation | transformation in simulation. It is a figure which shows angle distribution in simulation. It is a figure which shows the displacement distribution in simulation. It is a figure which shows a mode that the silicone rubber of a touch sensor is deform | transformed with the front-end | tip of a pencil. It is a figure which shows the acquired image in FIG. 7A. It is a figure which shows the decompression | restoration result in experiment. It is a figure explaining a contact state and shape distribution. It is a figure which shows thickness reduction of a tactile sensor. It is a figure which shows thickness reduction of a tactile sensor. It is a figure which shows non-contact observation using a tactile sensor. It is a figure which shows non-contact observation using a tactile sensor. It is a figure which shows combined use with a tactile sensor and a visual display. It is a figure which shows the other form of a tactile sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent elastic body 2 Image pattern 3 Camera 4 Reflecting surface 5 Object

Claims (8)

A transparent sensor body having a deformable reflective surface;
Image patterns,
An image acquisition element for acquiring a reflection image of the image pattern on the reflection surface using an optical lever;
Consists of
The reflective surface is formed from the interface by selecting the medium of the sensor body from a material having a higher refractive index than the outside that forms the interface with the sensor body, and the image pattern A light ray incident on the reflective surface and a light ray reflected from the reflective surface toward the image acquisition element are configured to form the reflected image by propagating in the medium of the sensor body.
The image acquisition element acquires different reflection images before and after the reflection surface is deformed;
A tactile sensor using reflected images.   The tactile sensor according to claim 1, wherein the sensor body includes a transparent elastic body at least in part, and the deformable reflective surface is formed of a transparent elastic body.   The part or all of the surface of the sensor body is formed of a film, the inside of the film is filled with fluid, and the deformable reflective surface is formed of the film. The tactile sensor described in 1. The image pattern and / or said image acquisition element is located outside the sensor body, tactile sensor according to any of claims 1 to 3. The transparent sensor body includes a plurality of surfaces, at least one of the plurality of surfaces forms the deformable reflective surface, and at least one of the plurality of surfaces is a light beam from an image pattern. The tactile sensor according to claim 4 , wherein a pattern surface on which light is incident is formed, and at least one of the plurality of surfaces forms a photographing surface from which reflected light from the reflecting surface is emitted. The transparent sensor body has a pattern surface group composed of a plurality of pattern surfaces parallel to each other, and an imaging surface group composed of a plurality of imaging surfaces parallel to each other, and each pattern surface and each imaging surface is The tactile sensor according to claim 5 , wherein the tactile sensors are alternately arranged. The reflecting surface is contacted surfaces in which the object is in contact, the tactile sensor according to any one of claims 1 to 6. A transparent sensor body having a deformable reflective surface;
Image patterns,
An image acquisition element for acquiring a reflection image of the image pattern on the reflection surface using an optical lever;
Reflecting surface reconstruction means;
Consists of
The reflective surface is formed from the interface by selecting the medium of the sensor body from a material having a higher refractive index than the outside that forms the interface with the sensor body, and the image pattern A light ray incident on the reflective surface and a light ray reflected from the reflective surface toward the image acquisition element are configured to form the reflected image by propagating in the medium of the sensor body.
The image acquisition element acquires different reflection images before and at the time of deformation of the reflecting surface,
The reflecting surface reconstruction means acquires the deformation of the reflected image when the object comes into contact with the contacted surface of the sensor body from the reflected image before and during the deformation of the reflecting surface acquired by the image acquisition element. A tactile sensor device using a reflection image that calculates the deformation of the reflection surface from the deformation of the reflection image.