JP2520211B2 - Tactile sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in the structure of a tactile sensor that utilizes the sensory series generated from the pressure sensation of the skin in engineering.

[0002]

2. Description of the Related Art As is well known, tactile sense plays an important role in human behavior along with vision. The engineering realization of this tactile function is extremely important in the field of intelligent robots. In particular, a distributed tactile sensor that detects a two-dimensional distribution of pressure and displacement is highly desired as a sensor that acquires information necessary for a robot to perform advanced object handling.

Regarding such a distributed type tactile sensor,
Although a sensor structure or a search method for object recognition using a tactile sensation has been studied so far, there are few practical ones, and the development of a sensor device is considerably delayed compared to the visual sense. The current situation.

By the way, the conventional tactile sensor disclosed in "Extracting the contour shape of a tactile object by an optical waveguide plate type distributed tactile sensor" (Publication of the Japan Society of Mechanical Engineers, No. 516, p. 2091 to 2099) is basically As shown in FIG. 4, a white elastic sheet 2 is arranged on the upper surface of the transparent plate 1, and the deformable elastic sheet 2 has a lower surface on the transparent plate 1 side. A large number of fine white protrusions 3 that come into contact with each other are provided in a protruding manner.

Therefore, the object 4 to be touched by the elastic sheet 2
As shown in FIG. 4, the protrusions 3 in the pressure contact region are crushed, and the contact area between the transparent plate 1 and the elastic sheet 2 is expanded. In this state, when the side surface of the transparent plate 1 is irradiated with light indicated by an arrow and observed from the lower surface, only the pressed portion of the object 4 is visually recognized brightly.

That is, since the transparent plate 1 and the elastic sheet 2 are in contact with each other at almost the same refractive index, the light radiated inside the transparent plate 1 is emitted to the elastic sheet 2 side. It is diffusely reflected by the white surface (scattered by particles in the elastic sheet 2) and passes through the transparent plate 1 to be visually recognized brightly, but the transparent plate 1 in a portion not in contact with the elastic sheet 2 is visible.
Forms an interface with air having a low refractive index, and the light is almost totally reflected inside the transparent plate 1 and is not leaked and emitted to the outside. Therefore, the above-mentioned light pattern is clearly observed.

Since the above-mentioned light pattern depends on the pressure contact shape of the object 4 to the elastic sheet 2, if this is detected by a light receiving system using a photoelectric conversion element, the shape information of the contact object 4 is obtained as an electric signal pattern. Is obtained, and the tactile sensor is configured.

Incidentally, as a prior art document of this kind, in addition to the above document, "Research on optical waveform fingertip tactile sensor" (Symposium on Robotics Automation System, 1991 9)
/ 12) and so on.

[0009]

Since the conventional tactile sensor is basically constructed as described above, there have been the following major problems. That is, according to the basic principle of the tactile sensor, when the object 4 is pressed against the elastic sheet 2, the protrusion 3 of the elastic sheet 2 is crushed to bring the transparent plate 1 and the elastic sheet 2 into contact with each other, and diffused light is generated at this contact portion. Occurs,
When the barycentric position of the diffused light is detected by using a light receiving lens and a semiconductor position detector (not shown), and the pressure contact position of the object 4 is detected, as shown in FIG. Since the tip of the portion 3 is also in contact with the transparent plate 1, diffused light is also generated from this contact portion.

For this reason, the semiconductor position detector has detected a combined barycentric position of two kinds of diffused light, which causes a serious problem that an error occurs with respect to the pressure contact position of the object 4.

The present invention has been made in view of the above, and an object thereof is to provide a tactile sensor capable of accurately detecting the pressure contact position of an object.

[0012]

In order to achieve the above-mentioned object in the present invention, a light source for making light incident on the inside of a transparent plate and a white surface on the inside of the transparent plate are provided so as to be covered with a gap. A sheet-shaped elastic body that is applied to the elastic body and is deformed by the action of external pressure, and a plurality of protrusions that are provided on the inner surface of the elastic body and are in substantially point contact with the surface of the transparent plate. In the one for detecting the contact position by detecting the diffused light generated at the contact portion between the portion and the transparent plate, a light absorbing portion that absorbs light is provided at the tip of the protruding portion.

[0013]

According to the present invention, since the black light absorbing portion that absorbs light is coated on the tip of the projection portion of the elastic sheet to which the white color is applied, the leakage that leaks out in the non-press contact area of the elastic sheet. All the light can be absorbed by the light absorbing portion, and it is possible to reliably prevent the generation of diffused light. Therefore, it is possible to provide a tactile sensor capable of detecting the contact position of an object extremely accurately by improving the contrast.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to an embodiment shown in FIG. 1. Basically, the tactile sensor according to the present invention is
A plurality of light sources 5 that allow light to enter the inside of the transparent plate 1, an elastic sheet 2 that covers the surface of the transparent plate 1 with a gap 6 in between, has an inner surface coated in white, and is deformed by the action of external pressure; A plurality of protrusions 3 are provided on the inner surface of the elastic sheet 2 and are in point contact with the surface of the transparent plate 1, and the protrusions 3 are provided.
A light absorbing portion 7 that absorbs light is applied to the tip of the.

The transparent plate 1 disposed between the plurality of upper light sources 5 is covered with a sheet-like elastic sheet 2 through a gap 6 on its surface, which is deformed by contact with the object 4. The inner surface of the elastic sheet 2 on the transparent plate 1 side is coated with white, and the inner surface, which is the reflective surface coated with the white color, has a substantially saw-toothed cross section that is substantially point-contacted with the surface of the transparent plate 1. A plurality of protruding portions 3 are provided so as to project. Then, a black light absorbing portion 7 that absorbs light shown by an arrow is applied to each of the sharp tips of the plurality of protrusions 3.

Therefore, the object 4 to be touched by the elastic sheet 2
1, the protrusions 3 in the pressure contact region are bent and crushed, as shown in FIG. 1, and the contact area between the transparent plate 1 and the elastic sheet 2 is expanded. When the contact area is expanded, in the pressure contact area of the elastic sheet 2, the portion of the protrusion 3 other than the tip provided with the light absorbing portion 7 is also crushed and comes into contact with the transparent plate 1, so that leakage occurs at this contact portion. The leaked light causes the elastic sheet 2 to generate diffused light.

On the other hand, in the non-pressure contact area of the elastic sheet 2, as shown in FIG. 1, the light absorbing portion 7 of the projection 3 is in point contact with the transparent plate 1, and the leaked light leaked out in this non-pressure contact area. All the light is absorbed by the light absorbing portion 7, and the generation of diffused light is reliably prevented.

However, the diffused light generated at the contact portion is received by the light-receiving lens 8 shown in FIG. 1 and imaged on the light-receiving surface of the semiconductor position detector 9, and the semiconductor position detector 9 is formed.
The accurate contact position of the object 4 is detected by detecting the center of gravity of the diffused light.

Next, FIG. 2 and FIG. 3 show in detail a tactile sensor of the size of a human fingertip using the above basic structure.
The tactile sensor mounted on the robot hand or the like includes a semiconductor position detector 9 electrically connected to an arithmetic processing circuit (not shown) and the like inside a base 10 having a substantially cylindrical exposed shape, and the base 10 A positive lens 11, an aperture lens 12, a negative lens 13, and a large-diameter negative lens 14 for sequentially forming diffused reflected light on the light receiving surface of the semiconductor position detector 9 are sequentially laminated at the center of the end face of the. A plurality of light emitting diodes (light sources 5) 15 provided with conductive wires are arranged side by side on the periphery of the end surface of the base 10 in a substantially ring shape.
A positive lens 11, a diaphragm lens 12, a negative lens 13, and a large-diameter negative lens 1 are mounted on the mounting seat 10a on the peripheral edge of
An approximately hemispherical shell-shaped light guide member (transparent plate 1) 16 that covers 4 is fitted.

The light guide member 16 is made of a transparent plate such as acrylic resin or glass, and is curved. The light emitted from the light emitting diode 15 is transmitted to the inside of the light guide member 16. It has the function of preventing dissipation. Therefore, the light guide member 16 is provided in the cover 1 described later.
A thin air layer (gap 6) 17 that effectively totally reflects light is interposed between the thin film and the air.

In addition, a flexible cover (elastic sheet 2) 18 having a substantially hemispherical shell shape is fitted on the peripheral edge of the end face of the base body 10 so as to cover the light guide member 16 with an air layer 17 interposed therebetween, and this deformable shape. White is applied to the inner surface of the cover 18 on the side of the light guide member 16, and the inner surface, which is the reflection surface coated with the white color, has a substantially saw-tooth cross section that makes a point contact with the surface of the light guide member 16. A plurality of white protrusions 3 are projected. And
As shown in FIG. 3, the sharp tips of the plurality of protrusions 3 are
Black light absorbing portions 7 that absorb light are each coated.

Therefore, when the cover 18, which is the sensing portion of the tactile sensor, comes into contact with the object 4 and is deformed, the cover 18 in the contact area is pressed against the light guide member 16 to expand the contact area, and the light guide member 16 is expanded. The light that is totally reflected in the light guide member 16 is diffusely reflected at the contact portion of the cover 18 and the cover 18. A part of this irregularly reflected light is refracted by the negative lenses 14 and 13, passes through the aperture of the diaphragm lens 12, and is imaged by the positive lens 11 on the light receiving surface of the semiconductor position detector 9. The accurate contact position of the object 4 is detected by detecting the position of the center of gravity of the light.

When the contact area is enlarged, the light absorbing portion 7 of the projection 3 is in point contact with the light guide member 16 in the non-pressure contact area of the cover 18, and the leaked light leaked out in this non-pressure contact area. Is completely absorbed by the light absorbing portion 7, and the generation of diffused light is reliably prevented.

According to the above configuration, since the black light absorbing portion 7 that absorbs light is applied to the tip of the protrusion 3 of the cover 18 to which the white color is applied, the leaked light leaked in the non-pressure contact area is leaked. Can be completely absorbed by the light absorbing portion 7, and the generation of diffused light can be reliably prevented. Therefore, it is possible to provide a tactile sensor capable of detecting the contact position of the object 4 extremely accurately by improving the contrast.

In the above embodiment, the black light absorbing portion 7 that absorbs light is simply applied to the tip of the projection 3 coated with white, but the tip of the projection 3 is exposed to light. Absorb and
Moreover, even if the light absorbing portion 7 made of a material that is easily adhered to the light guide member 16 (hard to slip) is provided, the same operational effect as that of the above-described embodiment can be expected, and further, the side slip of the protrusion 3 can be reliably prevented. The contact position of the object 4 can be detected extremely accurately.

[0026]

As described above, according to the present invention, since the black light absorbing portion that absorbs light is applied to the tip of the protrusion of the elastic sheet to which the white color is applied, the elastic sheet is not pressed. All the leaked light leaking in the region can be absorbed by the light absorbing portion, and the generation of diffused light can be reliably prevented. Therefore, there is a remarkable effect that a tactile sensor capable of detecting a contact position of an object very accurately can be provided very easily by greatly improving the contrast.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a tactile sensor according to the present invention.

FIG. 2 is an overall explanatory view showing another embodiment of the tactile sensor according to the present invention.

FIG. 3 is an enlarged explanatory view showing an enlarged part III of FIG.

FIG. 4 is a configuration diagram showing a basic principle of a conventional tactile sensor.

[Explanation of symbols]

1 ... Transparent plate, 2 ... Elastic sheet, 3 ... Projection part, 4 ... Object,
5 ... Light source, 6 ... Gap, 7 ... Light absorption part, 9 ... Semiconductor position detector, 15 ... Light emitting diode, 16 ... Light guide member, 17 ...
Air layer, 18 ... Cover.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-23104 (JP, A) JP-A 1-276034 (JP, A) JP-A 60-120229 (JP, A)

Claims (1)

(57) [Claims] 1. A light source for making light incident on the inside of a transparent plate,
A sheet-shaped elastic body which is covered with a gap on the surface of the transparent plate, the inner surface of which is applied in white, and which is deformed by the action of external pressure, and the surface of the transparent plate which is provided with a plurality of projections on the inner surface of the elastic body. In the tactile sensor for detecting the contact position by detecting the diffused light generated in the contact portion of the deformed elastic body and the transparent plate, the tip of the protrusion, A tactile sensor having a light absorbing portion for absorbing light.