Distributed proximity sensor system having embedded light emitters and detectors

• US 4,893,025 A
• Filed: 12/30/1988
• Issued: 01/09/1990
• Est. Priority Date: 12/30/1988
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: University of Southern California
• Inventors: Lee, Sukhan
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Allen, Stephone B.
• Application Number:
  US07/292,047
• Time in Patent Office: 375 Days
• Field of Search: 250/221, 250/222.1, 250/560, 250/561, 250/578, 356/1, 356/3, 356/4, 901/46, 901/47
• US Class Current: 250/559.33
• CPC Class Codes: B25J 13/086 Proximity sensors
• CPC Class Codes: G01S 17/04 Systems determining the presence of a target
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver

Abstract

A distributed proximity sensor system is provided with multiple photosensitive devices and light emitters embedded on the surface of a robot hand or other moving member in a geometric pattern. By distributing sensors and emitters capable of detecting distances and angles to points on the surface of an object from known points in the geometric pattern, information is obtained for achieving noncontacting shape and distance perception, i.e., for automatic determination of the object'"'"'s shape, direction and distance, as well as the orientation of the object relative to the robot hand or other moving member.

Claims

1. A distributed sensor system for robotics comprised of multiple proximity sensors embedded on the surface of a robotic moving member, each proximity sensor comprising a defined pattern of interspersed light emitters and receivers, each receiver having an aperture with a lens focusing light onto an array of photosensitive devices, and each light emitter comprising a light emitting diode and an optical guide to form a light beam with its axis tilted slightly toward the center of an adjacent receiver that is either closer or further from the center of said defined pattern, and with a dispersion angle sufficient to span said aperture of one of said light receivers toward which it is tilted.

2. A distributed sensor system as defined in claim 1 wherein each light receiver is comprised of a geometrically defined nonplanar surface embedded in said moving member and an array of photosensitive devices uniformly spaced on said geometrically defined nonplanar surface with said lens over said aperture through which reflected light is received to provide a pinhole camera effect in focusing light into the receiver, whereby the position one of said devices in the receiver which receives the most reflected light depends upon the incidence angle of the reflected light at the aperture, which in turn depends upon the distance and orientation of an object reflecting light from one of said emitters.

3. A distributed sensor system as defined in claim 2 including means for turning on said light emitters one at a time in a known sequence, thereby to enable each receiver to receive light from only one emitter at a time, whereby each receiver determines the distance of an object reflecting light from one emitter of known position relative to each receiver, and the distance of the object can be determined from an equation:

##EQU4## where X_c is the distance between the light emitter turned on and an axis of the light receiver, θ

₁ is the emitter tilt angle, and θ

₂ is the angle of the received light with respect to the axis of the receiver, whereby said sensor system provides information for achieving noncontacting perception capable of carrying out recognition of the three-dimensional shape of an object, its distance, and its relative position and orientation.

4. A distributed sensor system as defined in claim 1 wherein said pattern of interspersed light emitters and receivers is comprised of thirteen receivers distributed on two concentric circles, six on an outer circle at points defining a hexagon, and six on an inner circle at points defining a smaller hexagon centered on the outer hexagon, but with its points rotated 30°

from the points of the outer hexagon, and a thirteenth receiver at the center of the two concentric hexagons such that the centered receiver is spaced to form equilateral triangles with each two adjacent receivers on the inner hexagon, and each of the receivers on the outer hexagon forms an equilateral triangle with two adjacent receivers on the inner hexagon, and said light emitters are twelve in number dispersed with one in the center of each group of said three receivers that define an equilateral triangle.

5. A distributed sensor system as defined in claim 4 wherein each light emitter is comprised of a light emitting diode and an optical guide to form a light beam with its axis tilted slightly toward the center of an adjacent receiver that is either closer or further from the center of said concentric hexagons and with a dispersion angle sufficient to span one of said light receivers toward which it is tilted, whereby said twelve light emitters are dispersed on two circles, six on an outer circle, alternately tilted in and out with respect to the center of said concentric hexagons, and six on an inner circle alternately tilted in and out in a similar manner, and positioned on the same radial line as emitters on the outer circle, but tilted in the opposite direction from the emitters on the outer circle so that they alternately tilt toward and away from each other in six radial line positions spaced at 60°

intervals.

6. A distributed sensor system as defined in claim 5 wherein each light receiver is comprised of a geometrically defined nonplanar surface embedded in said moving member, and an array of photosensitive devices uniformly spaced on said geometrically defined nonplanar surface whereby the position of a photosensitive device in the receiver which receives the most reflected light depends upon the incidence angle of the reflected light, which in turn depends upon the distance and orientation of an object reflecting light from one of said emitters.

7. A distributed sensor system as defined in claim 6 wherein each receiver has a defined shape of a hollow hemisphere having said photosensitive devices uniformly spaced on the inside surface of said hollow hemisphere.

8. A distributed sensor system as defined in claim 6 wherein each receiver has a defined shape of a hollow cylinder with a reflecting cone having its base at the end of said cylinder opposite the end receiving light and its axis coincident with the axis of said hollow cylinder, and having said photosensitive devices spaced in linear arrays on the inside surface of a hollow cylinder, each linear array being disposed parallel to the axis of said hollow cylinder.