Decentralized Safe Control for Distributed Cyber-Physical Systems Using Real-Time Reachability Analysis

In this article, we present a decentralized safe control (DSC) approach for distributed cyber-physical systems based on conducting reachability analysis in real time. Each agent can periodically compute the local reachable set from its current local time to some time instant in the near future, and then broadcast a message containing the computed reachable set to the other agents via a shared communication channel. By comparing its own reachable set to unsafe regions such as obstacles, and received reachable sets in a peer-to-peer manner, the agent can predict if any collision may exist shortly. In this circumstance, the agent can utilize the unsafe intersection of its computed reachable set, the unsafe regions, and the received reachable sets to recalculate a new set of waypoints and update its corresponding control strategies. As a result, our DSC approach can ensure a distributed system achieving a mission goal with a collision-free guarantee. For evaluation, we applied the proposed DSC method to perform decentralized control, in real time, a group of quadcopters conducting a distributed patrol mission with safety guarantees.