Sensorless orientation of 3D polyhedral parts

A common task in automated manufacturing processes is to orient parts prior to assembly. We consider sensorless orientation of an asymmetric polyhedral part by a sequence of push actions, and show that is it possible to move any such part from an unknown initial orientation into a known final orientation if these actions are performed by a jaw consisting of two orthogonal planes. We also show how to compute an orienting sequence of push actions. We propose a three-dimensional generalization of conveyor belts with fences consisting of a sequence of tilted plates with curved tips; each of the plates contains a sequence of fences. We show that it is possible to compute a set-up of plates and fences for any given asymmetric polyhedral part such that the part gets oriented on its descent along plates and fences.

1 Introduction

An important task in automated assembly is orienting parts prior to assembly. A part feeder takes in a stream of identical parts in arbitrary orientations and outputs them in a uniform orientation. Often, part feeders use data obtained from some kind of sensing device to accomplish their task. We consider the problem of sensorless orientation of parts, in which no sensors, but only knowledge of the geometry of the part is used to orient it from an unknown initial orientation to a unique final orientation. In sensorless manipulation, parts are positioned or oriented using open-loop actions which rely on passive mechanical compliance. Figure 1: The feeder: plates with fences mounted to a cylinder.