Effect of Wind on the Connectivity and Safety of Large Scale UAV Swarms

Unmanned Aerial Vehicle (UAV) swarms are promising solutions to conduct different military and commercial missions. However, highly varying environmental factors such as wind make the UAVs unable to maintain the minimum safe distance between each other, and the UAVs at the edge of the swarm more vulnerable to connectivity loss from the swarm. The paper extensively studies the effect of wind on the connectivity and safety of a large scale swarm with one leader and multiple follower UAVs. We examined the relationship between different parameters including UAV speed, UAV mass, wind speed, drag force, and number of UAVs maintaining the desired safety and connectivity requirement in a swarm. Our analysis demonstrates that planning to fly the swarm at a speed closer (equal, if possible) to the mean value of the wind speed at the desired altitude increases the number of connected and safely flying UAVs. This choice of UAV speed, however, might not be the best solution when one considers the time constraint to reach the desired destination. And, when the UAVs are flying with a speed less than the wind speed, we get a smaller number of critical UAVs whereas, such a selection leads to a higher number of UAVs that do not meet the safety requirement of the swarm. To address this challenge, we propose to optimally and adaptively select the UAV speed so that the swarm reaches the target destination with the minimum/desired flight time while maintaining the connectivity and safety of most (all, if possible) of the UAVs.