Learning Safe Multi-UAV Coordination with Temporal-Spatial Constraints
Jean-Elie Pierre, Xiang Sun, Rafael Fierro · 2024
In Advanced Air Mobility applications, a group of autonomous uncrewed aerial vehicles (UAVs) may need to cooperate to arrive at their predefined destinations simultaneously to, for example, attack a target or carry heavy cargo. However, controlling a group of UAVs to arrive at destinations simultaneously is nontrivial as they have to meet spatial constraints, meaning that the control algorithm has to avoid collisions not only among UAVs but also between UAVs and non-cooperative flying objects (NCFOs), which are not coordinated by the control algorithm. The existing time-coordinated control algorithms can achieve simultaneous arrivals for a multi-UAV system but are unable to ensure collision-free trajectories. In this paper, we propose the safe terminal tiMe-cOordinated contRolleR for multI-uav Systems (MORRIS), a safe linear quadratic optimal control algorithm, which comprises two major parts, i.e., a terminal time-coordinated planner and a safety layer, where the terminal time-coordinated planner is to derive the accelerations of UAVs to minimize the difference between the arrival time and the predefined termination time for all the UAVs, and the safety layer applies a control barrier function (CBF) based solution to generate feasible accelerations of UAVs that ensure collision-free environment.