Self-Reconfiguration Using Graph Grammars for Modular Robotics

In this paper, we apply graph grammars to self-reconfigurable modular robots and present a method to reconfigure arbitrary initial configurations into prespecified target configurations thus connecting the motions of modules to formal assembly rules. We present an approach for centralized reconfiguration planning and decentralized, rule-based reconfiguration execution for three-dimensional modular structures. The reconfiguration is done in two stages. In the first stage, paths are planned for each module and then rewritten into production rules as defined for graph grammars. In stage two, these rules are applied in a decentralized fashion by each node individually.We show that our approach yields a unique reconfiguration sequence and a graph grammar that results in the target configuration being the only reachable stable configuration.