Consensus-Based Cooperative Formation Guidance Strategy for Multiparafoil Airdrop Systems

Parafoil airdrop is an important way to deliver goods and materials to area where road vehicles are not easy to reach. However, it is difficult to deliver large quantities of goods and materials to a given location with only one parafoil. Airdropping multiple parafoils is an effective choice for transporting large quantities of goods and materials. To realize the cooperative airdrop of multiple parafoils, a cooperative guidance framework is proposed. First, a trajectory planning algorithm is designed to plan the multiphase trajectory for the parafoil group. Then, a trajectory tracking algorithm is developed for the pilot parafoil in the parafoil group to reliably follow the planned trajectory. Finally, a cooperative formation guidance strategy is designed based on the leader-follower consensus theory. Under this strategy, the position and speed of the follower parafoil can be consensus with those of the leader parafoil. Lyapunov's theorem proves the stability of this strategy. We evaluate the effectiveness of this framework through simulations. The results demonstrate that our algorithms can realize the precise airdrop of massive goods and materials with upwind landing using multiple parafoils. In addition, the parafoils could be gradually gathered to a desired formation, and safe distances could be maintained between parafoils during the airdrop process. Note to Practitioners - This article was motivated by the problem of airdropping massive goods and materials. Existing methods usually adopt a single heavy parafoil, or use centralized multiparafoil systems. Both these methods have their limitations. For the former, there is an upper limit of the load capacity for a single parafoil. For the latter, the parafoils in the centralized system lack fully autonomous ability. Distributed multiparafoil systems could solve the problem effectively. However, compared to single-parafoil systems, there are still some challenges, for example, the multiparafoil gathering, collision avoidance and cooperative formation, as well as the upwind landing. Fortunately, existing parafoils are equipped with sensors, communication, and control devices, so they could be viewed as agents with autonomous capabilities. In this article, a formation guidance framework for multiple autonomous parafoils is proposed. First, we plan a trajectory for the pilot parafoil. Then, we show how to effectively track the planned trajectory. Finally, we demonstrate how multiple parafoils could coordinate with each other to accomplish airdrop tasks. The simulation results confirm the feasibility of this strategy.