Two- and three-dimensional part orientation by sensor-less grasping and pushing actions: use of the concept of 'attractive region in environment'

In our previous work, a concept attractive region in strategy investigation was proposed and it was proven that existence of these attractive regions is the essential and sufficient condition for reducing uncertainty. These attractive regions can be formed by active inputs based on sensory feedback or by passive inputs from constraints. The attractive regions were found and successfully used in three-dimension robotic assembly without force sensors and flexible wrist. Here the concept is successfully used in another important area, part orientation, which is also an essential step in manufacture. The main contribution of this paper includes: (1) the motion region of a general polygon with a flat parallel jaw gripper or a pushing fence is formed by attractive regions, (2) through use of these attractive regions, the algorithm to orient a polygon from arbitrary orientation to a unique orientation without feedback can be deduced straightforward, (3) the motion region of a general convex polyhedron with a flat parallel jaw gripper or a pushing fence in three dimensions is formed by various attractive regions and (4) through use of these attractive regions, an algorithm can be deduced directly based on the shape of a convex polyhedron, which can orient the polyhedron from an arbitrary orientation to a unique orientation without feedback.