JP2019197037A - Optical type tactile sensor - Google Patents

Abstract

To provide an optical type tactile sensor that is miniaturized and highly accurate.SOLUTION: An optical type tactile sensor 10 comprises: a contact deformation part 14 that is composed of elastically deformable light-blocking material; a light source 15 that supplies light to the contact deformation part 14; a light detection unit 16 that detects a change in amount of light from the light source 15 accompanied by elastic deformation of the contact deformation part 14; and a computation processing unit 13 that calculates external force acting on the contact deformation part 14 on the basis of a result of the detection. The contact deformation part 14 is composed of an inner cover 18 that forms a first space S1 in which the light detection unit 16 is stored; and an outer cover 19 that covers the inner cover 18 from the outside in a state separating a second space S2 to which the light from the light source 15 is supplied. The inner cover 18 is provided to be elastically deformable integrally with the outer cover 19, and has partially a translucent part 21 that transmits the light of the second space S2 to the first space S1. In the computation processing unit 13, a size of the external force is obtained based on a state change in amount of light accompanied by a displacement of the translucent part 21 when the external force acts on the contact deformation part 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical tactile sensor, and more particularly to an optical tactile sensor that can detect a minute change in external force with a relatively simple configuration.

  For robots that co-operate with humans, when a person or object in the environment surrounding the robot comes into contact with the robot, a tactile sensor that detects the pressing force or shear force acting on the contact part And the like, and the operation control of the robot is performed based on the detection value of the touch sensor or the like.

  As the tactile sensor, there is known an optical tactile sensor that calculates an external force based on a marker displacement by imaging a marker that is displaced by the addition of an external force with a camera. As this optical tactile sensor, for example, as shown in Patent Document 1, a sensor surface to which an external force is applied by contact of a person or an object and translucency in which different types of markers are provided inside are provided. A marker layer made of an elastic body, a sheet layer that is disposed between the sensor surface and the marker layer, and when an external force is applied to the sensor surface, the action site changes to brightness according to the magnitude of the external force; and the sensor A camera that is disposed on the opposite side of the surface and captures the marker and sheet layer in the marker layer, and an arithmetic unit that calculates the force distribution on the sensor surface based on the imaging result of the camera. In the calculation unit, the force distribution is calculated from the movement information of the marker for the marker in the marker layer facing the portion where the sheet layer becomes bright.

JP 2007-147443 A

  However, in the optical tactile sensor, in order to obtain a three-dimensional force distribution, a large number of markers must be three-dimensionally arranged in the marker layer. This increases the overall thickness of the sensor, and hinders the downsizing of the sensor when mounted on a robot. In addition, it is necessary to track each marker before and after the external force is applied to the sensor surface, and the calculation processing when obtaining the three-dimensional movement vector of each marker from the camera's imaging result becomes complicated. The load on each process for calculating the distribution increases. This problem becomes conspicuous when the size of each marker is reduced to improve performance so that even a fine external force can be detected.

  The present invention has been devised in order to solve such a problem. The object of the present invention is to facilitate the downsizing of the entire sensor with a relatively simple configuration, and even with a small change in the applied external force. It is an object of the present invention to provide a high-performance optical tactile sensor that can detect the magnitude and distribution of an external force through simple calculation processing.

  In order to achieve the above object, the present invention mainly includes a contact deformation part made of a light-shielding material that can be elastically deformed by the action of an external force, a light source that supplies light to a space formed inside the contact deformation part, A light detection unit that detects a change in the amount of light from the light source accompanying elastic deformation of the contact deformation unit, and an arithmetic processing unit that calculates an external force acting on the contact deformation unit based on a detection result of the light detection unit; In the optical tactile sensor, the contact deformation portion includes an inner cover that forms a first space in which the light detection portion is accommodated, and a light that is supplied from the light source outside the inner cover. The outer cover is arranged so as to cover the inner cover with a gap of two spaces therebetween, and the inner cover can be elastically deformed integrally with the outer cover by an external force acting on the outer cover. A translucent part that partially transmits the light in the second space to the first space, and the arithmetic processing unit includes a translucent part of the translucent part when an external force acts on the contact deformation part. A configuration is adopted in which the magnitude of the external force is obtained based on the change in the state of the light amount accompanying the displacement.

  According to the present invention, the light supplied from the light source to the second space is transmitted to the first space where the light detection unit is disposed through the light transmission part partially formed on the inner cover, and the magnitude and direction of the external force. Accordingly, the translucent portion is displaced by elastic deformation of the inner cover. Thereby, before and after the action of the external force, the magnitude of the light amount in the light detection unit and the central portion change, and the magnitude of the external force can be calculated three-dimensionally based on these state changes. For this reason, it is not necessary to calculate the three-dimensional movement vector of each marker as compared with the conventional method of imaging the marker with a camera, and the translucent part is arranged two-dimensionally along a plane, with a simple calculation. Thus, the size and distribution of the three-dimensional external force can be obtained, and the entire apparatus can be reduced in size and thickness. Furthermore, if the size of the translucent part is reduced and the light detection part can detect the amount of light for each fine detection area, the size and distribution of fine external force can be changed with a simpler structure without using a lens or the like. Can be detected with high accuracy.

The schematic block diagram of the optical tactile sensor which concerns on this embodiment. Sectional drawing which follows the AA line of the sensor main-body part of FIG. The conceptual diagram showing an example of the deformation | transformation state of the said sensor main body when external force acts. The schematic plan view for demonstrating the detection area | region of a photon detection part. The schematic plan view for demonstrating the definition of the position of each pixel and detection light quantity in one detection area of a photon detection part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration diagram of an optical tactile sensor according to the present embodiment. In this figure, the optical tactile sensor 10 is connected to a substrate 11 on which a predetermined electronic circuit is printed, a sensing unit 12 which is placed on the substrate 11 and serves as a detection site for external force, and a sensing unit 12. And an arithmetic processing unit 12 that calculates the magnitude and distribution of the external force acting on the sensing unit 12 based on detection by the sensing unit 12.

  The sensing unit 12 includes a contact deformation unit 14 made of a light-shielding material that can be elastically deformed by the action of an external force, a light source 15 that supplies light to the inside of the contact deformation unit 14, and a light source that accompanies elastic deformation of the contact deformation unit 14. 15 and a light detection unit 16 that detects a change in the amount of light from 15.

  The contact deformation portion 14 includes a gap serving as an inner cover 18 that forms a first space S1 in which the light detection portion 16 is accommodated, and a second space S2 to which light from the light source 15 is supplied outside the inner cover 18. And an outer cover 19 arranged so as to cover the inner cover 18 in a state of being separated from each other.

  Although the inner cover 18 is not particularly limited, the inner cover 18 has a hollow container shape having a square shape in a plan view opened at the lower end side in FIG. 1 and has light shielding properties and is elastically deformable. Further, as shown in FIG. 2, a large number of holes 21 are partially formed in the top wall at the upper end in FIG. 1 of the inner cover 18 in a regular arrangement state having the same pitch in the vertical and horizontal directions. Has been. These holes 21 penetrate between the inside and outside of the inner cover 18 and are disposed relative to the light detection unit 16. For this reason, light from the second space S2 located outside the inner cover 18 is introduced into the first space S1 that is the inner space of the inner cover 18 through the hole 21, and the amount of the introduced light is changed to the first space. It will be detected by the light detection unit 16 arranged in S1. Since the inner cover 18 is formed of a light-shielding material, the light flow between the outer second space S2 and the inner first space S1 is performed only through the hole 21. As described above, the hole portion 21 constitutes a light transmitting portion that transmits the light in the second space S2 to the first space S1.

  The translucent portion is not limited to the hole portion 21 of the present embodiment. For example, the light transmitting portion has a similar function such as partially forming the light-shielding inner cover 18 with a translucent material. As long as it plays, various aspects can be taken.

  Similar to the inner cover 18, the outer cover 19 has a hollow container shape with a rectangular shape in a plan view opened at the lower end side in FIG. 1, has a light shielding property and is elastically deformable. For this reason, the light from the light source 15 irradiated to the second space S between the inner cover 18 and the outer cover 19 does not leak to the outside of the outer cover 19, but only through the hole 21 formed in the inner cover 18. The light detection unit 16 is reached.

  Although the inner cover 18 and the outer cover 19 are not shown in the drawing, a part of them is connected. The inner cover 18 can be elastically deformed integrally with the outer cover 19 according to the sheath direction. For this reason, as shown in FIG. 3, the holes 21 can be displaced in the three orthogonal directions along with the elastic deformation of the inner cover 18 due to the action of the external force F on the outer cover 19.

  The light source 15 is not particularly limited, and is configured by LED lights installed at a plurality of positions on the substrate 11 between the inner cover 18 and the outer cover 19, and between the inner cover 18 and the outer cover 19. The second space S2 can be irradiated with light.

  The light detection unit 16 is electrically connected to the substrate 11 and is not particularly limited, but is constituted by a C-MOS sensor. As will be described later, the light detection unit 16 generates an electrical signal in accordance with the received light amount in addition to other imaging elements such as a CCD as long as the light amount can be detected for each detection region within a predetermined range. It is also possible to apply general photoelectric conversion elements.

  The arithmetic processing unit 12 is configured by a computer including an arithmetic processing device such as a CPU and a storage device such as a memory and a hard disk, and the three orthogonal axes that act on the contact deformation unit 14 based on the detection result of the light detection unit 16. The external force in each direction is calculated. That is, the calculation processing unit 12 calculates the magnitude and distribution of the external force in each direction based on the change in the amount of light detected by the light detection unit 16 before and after the action of the external force on the contact deformation unit 14. In the following description, among the three orthogonal axes, the shear direction along the surface of the contact deformation portion 14 is the x-axis direction and the y-axis direction, and the pressing direction orthogonal to the surface of the contact deformation portion 14 is the z-axis direction. .

  The calculation processing unit 12 is a pressing force calculation unit 23 that calculates the magnitude of the pressing force that is an external force in the z-axis direction with respect to the contact deformation unit 14, and an external force in the x-axis direction and the y-axis direction with respect to the contact deformation unit 14. A shearing force calculating unit 24 for calculating the shearing force.

Here, as shown in FIG. 4, the light detection unit 16 facing each hole 21 is divided into a plurality of detection regions A _q (q = 1, 2,..., R−1, r). For each detection region A _q , the pressing force is calculated by the pressing force calculator 23 and the shear force is calculated by the shear force calculator 24.

Each of these detection areas A _q is assigned an area that can cover a range in which one opposing hole 21 is displaced, that is, the number of pixels, and each of the one opposing hole 21 passes through the corresponding hole 21. The distribution of the amount of light accompanying the change in the state of the light to be detected can be detected for each detection region _Aq .

For example, in the case of the schematic configuration example of FIG. 5, 5 × 5 pixels are allocated to each of the ₁₆ divided detection areas A _{1 to} A ₁₆ . Then, for each of the detection areas A _{1 to} A ₁₆ , the pressing force and the shear force are obtained, and the distribution of the external force that has acted on the contact deformation portion 14 is specified in units of the detection area A _q .

In the following description, when describing each pixel in the detection area A _q , the xy coordinate system shown in FIG. 5 is used, the pixel located at the center is set as the origin, and the right side in the figure on the x axis is the right side. The lower direction in the figure on the direction and the y-axis is the positive direction. Further, the x-axis coordinate i and the y-axis coordinate j are set, and the pixel position is P (i, j) (i = −m, −m + 1, 0,..., M−1, m) (j = −n, −n + 1, 0,..., N−1, n). In the example of FIG. 5, i = −2, −1, 0, 1, 2 and j = −2, −1, 0, 1, 2.
Also, it represents the amount of light detected by the respective pixel P (i, j) in the detection area _{A q S i,} and _j.

In the pressing force calculation unit 23, for each detection region A _q of the light detection unit 16, each pixel P (i in the same detection region A _{q with} respect to a reference state where no external force is acting on the contact deformation unit 14. , J), the pressing force is obtained based on the increase in the total sum of the light amounts S _{i, j} detected.

Specifically, first, the detection areas _A q of the light detection unit 16 (q = 1,2, ···, r-1, r) in, after the external force acts, each pixel of the detection area _{A q} P ( The sum SR _{q of} the light amounts S _{i, j} detected in i, j) is obtained. That is, in the example of FIG. 5 _, the total sum SR _q of the light amounts S _{i, j} for 25 pixels is obtained in each of the ₁₆ divided detection areas A _{1 to} A ₁₆ .

Then, as expressed by the following equation, a preset gain is obtained by subtracting the preset total light quantity SB _q of the same detection region A _q in the reference state from the total light quantity SR _q after the external force action. by multiplying the C, quantity S _i before and after external force _action, on the basis of a change in _j, the pressing force Fz _q of each region a _q is obtained.

In the shearing force calculating unit 24, first, for each of the detection areas A _q respectively, the detection area A each pixel constituting the _q P (i, j) amount detected by the S _i, with _j, from the reference state The movement distances Dx and Dy in the x-axis direction and the y-axis direction of the central portion of the light are obtained, and the shear force in these directions is obtained according to the movement distances Dx and Dy.

Here, the movement distance Dx in the x-axis direction and the movement distance Dy in the y-axis direction are obtained by the following equations. In each detection region _Aq , in the reference state, each corresponding hole 21 is set to be opposed to the central pixel P (0, 0) serving as the origin, and the central pixel P ( 0,0) is the central portion of the light in the reference state.

That is, in the above equation, the movement distance Dx in the x-axis direction is the distance from the coordinates in the x-axis direction, that is, the origin, to the detected light amount S _{i, j} for each pixel P (i, j) in the detection region A _q. The sum of the values obtained by multiplying the distance i is obtained by dividing by the sum SR _q of the light amounts S _{i, j} at each pixel P (i, j) in the same detection area A _q .

Similarly, the movement distance Dy in the y-axis direction is obtained by setting the detected light quantity S _{i, j} to the coordinates in the y-axis direction, that is, the separation distance j from the origin, for each pixel P (i, j) in the detection area A _q. The sum of the multiplied values is obtained by dividing by the sum SR _q of the light amounts S _{i, j} at each pixel P (i, j) in the same detection area A _q .

The moving distance Dx, for Dy in the detection areas A _q, is not limited to the calculation method described above, may be obtained using other techniques.

Then, by the following equation, and the shear force Fy _q shear force Fx _q and y-axis direction of the x-axis direction in the detection areas A _q is obtained.

上式において、Ｋ_１〜Ｋ_５、Ｐ_１〜Ｐ_５は、予め設定されたゲインである。

In the above equation, K _{1 to} K ₅ and P _{1 to} P ₅ are preset gains.

  According to the above embodiment, the pressing force of the external force acting on the outer cover 19 is detected by detecting the change in the light transmission state by the holes 21 formed in large numbers along the upper surface of the inner cover 18 in FIG. Unlike the conventional method using many markers arranged three-dimensionally, the magnitude and distribution of the external force can be obtained with a simple calculation. Therefore, it is possible to promote downsizing and thinning of the entire sensor.

  The configuration of each part of the apparatus in the present invention is not limited to the illustrated configuration example, and various modifications are possible as long as substantially the same operation is achieved.

DESCRIPTION OF SYMBOLS 10 Optical tactile sensor 13 Operation processing part 14 Contact deformation | transformation part 15 Light source 16 Photodetection part 18 Inner cover 19 Outer cover 21 Hole (translucent part)
23 pressing force calculation unit 24 shearing force calculation unit A _q detection area S1 first space S2 second space

Claims (4)

A contact deformation portion made of a light-shielding material that can be elastically deformed by the action of an external force, a light source that supplies light to a space formed inside the contact deformation portion, and a light source from the light source accompanying the elastic deformation of the contact deformation portion. In an optical tactile sensor comprising: a light detection unit that detects a change in the amount of light; and an arithmetic processing unit that calculates an external force applied to the contact deformation unit based on a detection result of the light detection unit.
The contact deformation part is a state in which a gap is formed between an inner cover that forms a first space in which the light detection part is accommodated and a second space to which light from the light source is supplied outside the inner cover. And an outer cover arranged to cover the inner cover with
The inner cover is provided so as to be elastically deformable integrally with the outer cover by an external force acting on the outer cover, and a translucent portion that partially transmits light in the second space to the first space. Have
In the arithmetic processing unit, the magnitude of the external force is obtained based on a change in the state of the light amount accompanying the displacement of the translucent portion when an external force is applied to the contact deformation portion. . The translucent part is provided to be opposed to the light detection part at a plurality of locations within a predetermined plane,
The light detection unit is divided into detection regions that can detect a change in the amount of light before and after the displacement of the contact deformation unit for each light transmission unit with respect to the light transmitted from the light transmission units to the first space,
The optical tactile sensor according to claim 1, wherein the arithmetic processing unit calculates the magnitude of the external force for each of the detection regions and obtains a distribution of the external force that has acted on the contact deformation unit. The calculation processing unit includes a pressing force calculation unit that calculates a pressing force with respect to the contact deformation unit,
The pressing force calculation unit obtains the magnitude of the pressing force based on an increase in the total amount of light in the detection region with respect to a reference state in which the external force does not act on the contact deformation unit. The optical tactile sensor according to claim 2. The calculation processing unit has a shear force calculation unit for calculating a shear force with respect to the contact deformation unit,
The shearing force calculation unit obtains the magnitude of the shearing force based on a moving distance of a central portion of the amount of light in the detection region with respect to a reference state where the external force does not act on the contact deformation unit. The optical tactile sensor according to claim 2.

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