A reconfigurable parts feeder with an array of pins

Abstract

This paper presents a simple parts feeder consisting of a grid of retractable pins on a vertical plate to manipulate polygonal parts. This reconfigurable "Pachinko machine" is intended as a parts feeding device for flexible assembly. A part dropped on this device may come to rest on the actuated pins, or bounce out or fall through. We can control the set of equilibrium part configurations by selecting the set of actuated pins. The objective is to automatically compute sequences of pin actuation that bring the part to a goal configuration without predicting the exact object motion between equilibria. Our approach is based on the construction of the capture region of each part equilibrium. Reorienting a part reduces to building a directed graph whose nodes consist of equilibria and whose area link pairs of nodes such that the first equilibrium lies in the capture region of the second one, and then exploring this graph to find paths from initial to goal states. We have implemented an algorithm to generate the capture regions and these paths, and have conducted experiments on a prototype Pachinko machine.