Safe formation control of multiple unmanned aerial vehicles: control design and safety-stability analysis

Both safety and stability are primary performance criteria for multi-unmanned aerial vehicle (multi-UAV) systems in many coordination tasks. Existing approaches often consider safety and stability separately. It is necessary and urgent to develop a safety-stability control strategy to merge these two performance criteria. In this paper, a unified approach is developed to consider safety and stability for multi-UAV formation control. The stability criterion is represented by a Lyapunov function and safety criterion is represented by a barrier function and then a relaxed converse control Lyapunov-barrier theorem is obtained. With the help of a relaxed converse control Lyapunov-barrier function (RCCLBF), a distributed safety-stability formation control strategy is proposed for the multi-UAV system. By transforming the solution of RCCLBF to a Lyapunov-like stabilization problem, we show that the proposed formation control strategy can drive the UAVs staying within a specified safe set. Simulation results are provided to validate the proposed safety-stability formation control strategy.