BLAS: Broadcast Relative Localization and Clock Synchronization for Dynamic Dense Multiagent Systems

Spatiotemporal information plays crucial roles in a multiagent system (MAS). However, for a highly dynamic and dense MAS in unknown environments, estimating its spatiotemporal states is a difficult problem. In this article, we present BLAS-a wireless broadcast relative localization and clock synchronization system to address these challenges. Our BLAS system exploits a broadcast architecture, under which a MAS is categorized into parent agents that broadcast wireless packets and child agents that are passive receivers, to reduce the number of required packets among agents for relative localization and clock synchronization. We first propose an asynchronous broadcasting and passively receiving protocol. The protocol schedules the broadcast of parent agents using a distributed time division multiple access scheme and delivers interagent information used for joint relative localization and clock synchronization. We then present distributed state estimation approaches in parent and child agents that utilize the broadcast interagent information for joint estimation of spatiotemporal states. The simulations and real-world experiments based on ultra-wideband illustrate that our proposed BLAS can not only enable accurate, high-frequency, and real-time estimation of relative position and clock parameters but also support theoretically an unlimited number of agents.