A tracking vision sensor system

The initial aim was to develop a nontactile scanner capable of tracking a weld seam during robot welding operations. In addition, it was intended to investigate AGV guidance and surface inspection applications. The scanner is based on the 'flying spot' principle as described by Batchelor et al. (1985), with a low power helium-neon laser scanned across the work-piece by means of a mirror rotated at constant speed using a stepper motor. Clearly the scan rate of the laser across the work-piece is determined by the number of sides on the mirror and the switching rate of the motor, while the scan length is a function of the distance between mirror and work-piece and the number of sides on the mirror. An eight-sided mirror has been selected as this gives the maximum scan rate with the required scan length and stand off height.<
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