Orienting parts by inside-out pulling

A common task in automated manufacturing processes is that of orienting (or feeding) parts prior to assembly. We propose a new type of feeder. We consider sensorless orientation of polygonal parts with elevated edges by pull actions with an overhead finger. We show that any asymmetric convex polygonal part can be oriented by a sequence of pull operations. We give an O(n/sup 3/) algorithm to compute the shortest sequence of pull operations to orient a convex polygonal part with n vertices, if such a sequence exists. We also show that there exist non-convex parts that cannot be fed by a sequence of pull operations.