JP3173180B2 - Distributed 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 a tactile sensor,
More particularly, the present invention relates to a distributed tactile sensor that is applied to an industrial robot hand and the like, and simultaneously measures a contact position and a contact pressure of an object when the object is grasped.

[0002]

2. Description of the Related Art Conventionally, as a distributed tactile sensor, a white elastic sheet having irregularities on one surface of a transparent plate is provided, and CCD elements are arranged on the other surface so that the convex portions are in contact with the transparent plate.
Light is incident from the side of the transparent plate, and when a force is applied to the white elastic sheet, the unevenness is broken and the white elastic sheet adheres to the transparent plate, so that light in the transparent plate leaks to the white elastic sheet and is scattered. There has been proposed a method of obtaining shape information and contact pressure information of an object by detecting and processing signals with a CCD element disposed on the opposite side of a transparent plate (for example, Japanese Utility Model Application Laid-Open No. Sho64).
-42431). FIG. 5 shows a principle diagram of a conventional tactile sensor, and FIG. 6 shows a system configuration diagram. 4a is a light source, 1 is a transparent waveguide, 3a is a white elastic sheet, 7 is a CCD element, and 6 is a signal processing unit. Light incident on the side surface of the transparent plate 1 from the light source 4a is confined in the transparent plate 1 while undergoing total reflection. When the contact object is in a separated state, the white elastic sheet makes point contact with the transparent plate at the convex portion. When the contact object presses the white elastic sheet 3a having the uneven portion, the uneven surface is collapsed according to the force, and the white elastic sheet 3a comes into contact with the transparent plate 1 over a wide area. As a result, the condition of total reflection of light on the surface of the transparent plate 1 is broken, and the light leaks to the white elastic sheet and is scattered on the white elastic sheet surface. The scattered light is received by the CCD element 7 provided on the opposite side of the transparent plate, converted into an electric signal, and subjected to the signal processing in the signal processing section 6, whereby the shape information and the contact pressure information of the contact object can be obtained.

[0003]

However, in this conventional example, it is difficult to realize a uniform light intensity distribution on the surface of the transparent plate 1, and correct shape information and contact pressure information cannot be obtained. Also, when the object contacts a large area or when there are two or more objects, light scattering occurs more strongly in a portion where the light intensity distribution is strong, and the light is attenuated. The correct shape information and the absolute value of the contact pressure information are not always given between objects. The present invention solves such a problem and proposes a distributed tactile sensor that gives accurate shape information and contact pressure information.

[0004]

In order to solve the above problems, the present invention provides a transparent waveguide having a light beam source on one side and an optical sensor on the other side, and a refractive index larger than the transparent waveguide. And a distributed elastic tactile sensor including a transparent elastic sheet having an uneven surface and a means for scanning the light beam.

[0005]

By providing a beam direction control mechanism to the light beam source, accurate contact pressure information at each detection point can be obtained, and accurate contact pressure information at all detection points can be obtained by scanning the probe light beam. Because you can
When the contact object is pressed, the accurate shape information and the contact pressure information can be detected in the signal processing unit.

[0006]

FIG. 1 shows a first embodiment of the present invention. In the figure, 1 is a transparent waveguide, 2 is an optical sensor, 3 is a transparent elastic sheet, 4 is a light beam source, 41 is a light beam, 5 is a piezo element, 51 is a piezo element driving circuit, and 6 is a signal processing unit. . FIG. 4 shows a detailed view of the light beam source. In the figure, reference numeral 42 denotes a laser diode (or LED).
43 is a collimator lens system. The light emitted from 42 is converged at 43 and becomes parallel beam light 41. The piezo element is driven by a command from the signal processing unit 6. Due to the driving amount, the light beam 41 from the light beam source 4 enters the transparent waveguide 1 at an angle so as to be totally reflected. When no force is applied to the transparent elastic sheet 3, the uneven portion makes point contact with the transparent waveguide 1 at the detection point 8. Therefore, the light beam from the light beam source 4 reaches the optical sensor 2 without being attenuated. When a force is applied to the transparent elastic sheet 3, the unevenness is broken, and a portion is brought into close contact between the transparent elastic sheet and the transparent waveguide 1. Now, since the refractive index N2 of the transparent elastic sheet is larger than the refractive index N1 of the transparent waveguide 1, if a portion where 1 and 3 come into close contact as described above occurs, the light beam 4 passing through this portion
1 passes through the transparent elastic sheet 3. That is, when a contact object is pressed against the transparent elastic sheet, the unevenness of the transparent elastic sheet collapses in accordance with the force, and the contact area between the transparent elastic sheet and the transparent waveguide increases. The condition is broken and the light passes through the transparent elastic sheet. as a result,
The light beam 41 is attenuated in proportion to the contact area.
This light attenuation is detected by the optical sensor 2 to detect the amount of light, and the signal processing unit 6
The magnitude of the force applied to the force detection point on the transparent waveguide 1 corresponding to the angle of incidence of the light beam 41 can be obtained by performing the signal processing in step (1).

FIG. 2 shows a second embodiment of the present invention. In the figure, 5a is a piezo element for vertical driving, 5b is a piezo element for horizontal driving, 51a is a driving circuit of 5a, 5a
1b is a drive circuit of 5b. Even when the force detection points are extended two-dimensionally, the magnitude of the force applied to each force detection point can be obtained by the same mechanism and signal processing.

FIG. 3 shows a third embodiment of the present invention. This is a case where an optical fiber is used as a transparent waveguide. In the figure, 1 is a transparent waveguide (in this case, the core of an optical fiber), 11 is a low refractive index layer (in this case, the cladding of an optical fiber), 2 is an optical sensor, 70 is a detection point which is not attenuated,
Reference numeral 71 denotes a detection point to be attenuated, 410 denotes an optical path of the light beam 41 that is not attenuated, and 411 denotes an optical path of the light beam that is attenuated. The incident angle of the light beam 41 is made variable to make the optical path 411.
By this, the beam passing through the detection point 71 to which the haptic pressure f is applied leaks out of the optical fiber waveguide, so that the light beam entering the optical sensor 2 is reduced. By scanning the detection point 71, the position and size of the detection point to which the tactile pressure f is applied can be known.

[0009]

As described above, according to the present invention, since the probe light beam can be scanned, the contact pressure information at each detection point can be accurately obtained, and the contact pressure information is measured and processed at all the detection points. As a result, a distributed tactile sensor that provides accurate shape information and tactile pressure information of a contact object is obtained.
Further, the use of an optical fiber as the transparent waveguide has an effect of achieving a compact structure.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the present invention.

FIG. 3 is a configuration diagram showing a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a light beam source.

FIG. 5 is a principle diagram of a conventional distributed tactile sensor.

FIG. 6 is a system configuration diagram of a conventional distributed tactile sensor.

[Explanation of symbols]

 Reference Signs List 1 transparent waveguide 11 low refractive index layer 2 optical sensor 3 transparent elastic sheet 3a white elastic sheet 4 light beam source 4a light source 5 piezo element 5a vertical driving piezo element 5b horizontal driving piezo element 41, 410, 411 light beam 42 Laser Diode 43 Collimator Lens System 51 Piezo Element Driving Circuit 51a Vertical Driving Piezo Element Driving Circuit 51b Horizontal Driving Piezo Element Driving Circuit 6 Signal Processing Unit 7 CCD Element 8, 70, 71 Detection Point

────────────────────────────────────────────────── ─── Continued on the front page Examiner Yuji Fukuda (56) References JP-A-60-120229 (JP, A) JP-A-62-128317 (JP, A) JP-A-2-115919 (JP, A) JP-A-63-269002 (JP, A) JP-A-61-272605 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01L 5/00 G01B 11/00

Claims (4)

(57) [Claims] 1. A transparent waveguide having a light beam source on one side and an optical sensor on the other side, a transparent elastic sheet having a refractive index larger than that of the transparent waveguide and having an uneven surface, A distributed tactile sensor having a scanning unit. 2. The distributed tactile sensor according to claim 1, wherein the means for scanning the light beam is a means for controlling the beam direction of the converged laser diode light or LED light by a piezo element. 3. The distributed tactile sensor according to claim 1, wherein the means for scanning the light beam is a means for controlling a refractive index of an output portion of the laser diode to control a direction of the light beam. 4. The distributed tactile sensor according to claim 1, wherein an optical fiber is used as the optical waveguide.