Air-recovery method of Unmanned Aerial Vehicles Swarm with Lower Speed Based on Backstepping

The swarm of the UAVs is characterized by flexibility and concealment. At present, Many countries are competing to develop the technology of UAVs swarm. Air-based launch and recovery of the swarm can overcome the constraints of geographical environment, which have the characteristics of rapid deployment and evacuation. This technology will become an important way for deployment and withdrawing of the swarm in the future. However, there is a large gap between the cruising speed of the UAV and the carrier, which has become an urgent problem to be solved in the way of air-recovery. In this paper, we establish the model of "mothership-cable-net" based on the theory of "tow-cable". The constraint of internal states of the model is analyzed, and a closed-loop control scheme that makes the recovery net slower but stable at a constant height is built. To reduce the speed of the recovery net and make it converge to the predefined height without changing the height of the carrier, a nonlinear controller based on backstepping technique is designed which can also adaptively adjust the recovery net with different damping coefficients. Finally, the effectiveness of the proposed scheme is verified by simulation experiments.