Orienting Polygonal Parts without Sensors

In manufacturing, it is often necessary to orient parts prior to packing or assembly. We say that a planar part is polygonal if its convex hull is a polygon. We consider the following problem: given a list of n vertices describing a polygonal part whose initial orientation is unknown, find the shortest sequence of mechanical gripper actions that is guaranteed to orient the part up to symmetry in its convex hull. We show that such a sequence exists for any polygonal part by giving an O(n 2 log n) algorithm for finding the sequence. Since the gripper actions do not require feedback, this result implies that any polygonal part can be oriented without sensors. Keywords: Robotics, Parts Feeding, Planning, Grasping, Compliance, Motion Planning with Uncertainty, Compliant Motion Planning. 1 Introduction Manufacturing processes such as injection molding and stamping often produce a stream of parts that must be reoriented before assembly. A parts feeder is a machine that orients parts (Figu..