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An Optical Proximity Sensor for Measuring Surface Position and Orientation for Robot Manipulation.

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The authors developed a noncontact proximity sensor which can measure the distance and orientation of a surface in a range of four to five centimeters. The sensor is based on the scheme of active illumination and triangulation. It uses multiple infrared LEDslight emitting diodes as the light sources and a PIN-diode area sensor chip for detecting the spot positions. Six LEDs with optics for collimating the beam are mounted at the sensor head. The directions of the beams are aligned to form a cone of light converging at a distance of 4.5 cm from the sensor head. As each LED is sequentially pulsed, the sensor chip detects the position, in its field of view, of the spot projected by the LED light beam on the object surface. The 3-D location of the spot on the surface can be computed by triangulation. By doing this for six LEDs a set of six 3-D points is obtained. Then by fitting a plane to those points, the distance and orientation of a small portion of the object surface are calculated. Since there is no moving part and the spot position sensor chip is a analog sensor which outputs the position of the spot directly without scanning its field of view, fast operation of the proximity sensor can be realized. Currently the sensor can give approximately 1000 measurements of distance and orientation per second with precision of 0.07 mm for distance and 1.5 deg for surface orientation. This non-contact proximity sensor will be useful for such applications as tracing an object surface by a robot arm with specified distance and orientation relative to the surface. Author

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  • Test Facilities, Equipment and Methods
  • Optical Detection and Detectors

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