Practical pushing planning for rearrangement tasks

Rearrangement of objects by pushing is a basic manipulation task. The authors (1995) presented a resolution-complete algorithm that plans optimal pushing manipulations for rearrangement tasks but operates in high time and space complexity. In this paper the authors address the issue of practical planning for the same kind of problems. Rather than using a classical heuristic method, the authors propose an alternative approach. The authors present a hierarchical classification of the pushing problems domain into several classes, each characterized by properties of the plans that can solve it. Such a classification allows the authors to consider each class individually, analyze and exploit properties of each class, and suggest individual planning methods. Algorithms for two of the defined classes are presented. Both algorithms were tested in a simulated environment, with up to 32 movable objects and 66 combined DOF. Some of these simulations are presented here.