Distributed Motion Planning for 3D Modular Robots with Unit-Compressible Modules

Self-reconfigurable robots are versatile systems consisting of large numbers of independent modules. Effective use of these systems requires parallel actuation and planning, both for efficiency and independence from a central controller. This paper presents the PacMan algorithm, a technique for distributed actuation and planning. This algorithm works on systems with twoor three-dimensional unitcompressible modules. We give a simplified version of the algorithm along with extensions that handle a larger class of parallel actuation. For both algorithms, we present correctness analysis that show the classes of reconfigurations that can be guaranteed to be achieved. For the extensions, we give proofs of parallel actuation capability that describe how several modules can move simultaneously without synchronization while retaining correctness. We have successfully instantiated the basic algorithm onto the Crystal, a self-reconfigurable robot system, and present hardware experiments.