Title
A Complete Algorithm for Designing Passive Fences to Orient Parts

Abstract
Peshkin and Sanderson[18] showed that parts can be aligned as they move on a conveyor belt against a passive sequence of fences. In this paper we describe the first complete algorithm to design such sequences for a given convex polygonal part. The algorithm is complete in the sense that it is guaranteed to and a design if one exists and to terminate with a negative report otherwise. Based on an exact breadth-first search of the design space, the algorithm is also guaranteed to find the design requiring the fewest fences. We describe the algorithm and compare results with those previously reported. We conjecture that a fence design exists to orient any convex polygonal part.

Source: 1996 IEEE International Conference on Robotics and Automation

Title
Curved Fences for Part Alignment on a Belt

Abstract
In automated packing or assembly it is often necessary to bring randomly oriented parts into uniform alignment. Mechanical methods such as vibratory bowl feeders are often used for this purpose, although there is no theory for the systematic design of such feeders. A slanted fence attached to the stationary sides of a conveyor belt is also capable of orienting a stream of parts and a sequence of such fences has been shown to function as a systematically designable linear parts feeder.

A limitation of fence alignment is that once a part has left contact with a fence, its final orientation is confined to a narrow range of angles but is not unique. Here we consider the design of a single fence, consisting of a straight slanted section followed by an optimal curved tail. The straight section selectively aligns certain edges of the part, while the curved tail preserves this alignment precisely as the part leaves contact with the fence. We have found the shortest tail which guarantees alignment.

Optimal curved fences may be used individually for alignment of parts on a conveyor belt. They also lend themselves to systematic design of multi- fence linear parts feeders.

Source: ASME Journal of Mechanical Design, 117 (1), March 1995 (p. 27)