Persistence Acquisition and Maintenance for Autonomous Formations

Built upon a recently developed theoretical framework, we consider some practical issues raised in autonomous multi-agent formation control. We use the notions of rigidity and persistence to analyze the cohesiveness of the formation structure and maintenance of the constraints on each individual agent. We present basic properties of persistent formations and give an operational criterion to determine if a formation is persistent. Using the framework we develop, we seek to provide systematic ways of acquiring persistence for classes of formations often found in real world applications. Decentralized automatic acquisition of persistence for rigid formations is an open problem and answers found for these specific examples may serve as hints for seeking a general solution. Another focus of this paper is on how to transfer autonomy (abstracted as degrees of freedom) among agents, when the formation changes with new agent(s) added, to preserve persistence.