Robotic sorting of paper items from a random pile

A random stack of documents is physically sorted into ordered stacks accord ing to type and condition. This is done by first locating the topmost item using a machine vision system with algorithms based upon the Hough Transfor m. The edges of the items are identified from the shadows created by illumi nating the pile from different directions. Having located the position and orientation of the topmost item, a robot arm is programmed to pick the item from the pile using an end-effector with vacuum picking mechanisms. The ro bot arm offers the picked item "on-the-fly" to devices which ascertain its physical fitness and classification. Finally, the item is placed on the app ropriate one of a number of piles of similar category. (C) 2000 Elsevier Sc ience Ltd. All rights reserved.