Robust formation control for unmanned helicopters with collision avoidance

A systematic framework is proposed which addresses fully distributed formation control of under actuated unmanned helicopters (UHs) with resisting the external disturbances and model uncertainty capability. In this paper, a hierarchical control strategy for the whole closed-loop under-actuated UHs system is applied. The adaptive terminal sliding mode (TSM) control technique is employed to design an continuous fast robust controller in each loop and an integral filter is introduced between the position loop and the attitude loop to ensure that the attitude controller can track the desired attitude command. The stability of the whole closed-loop system is guaranteed through Lyapunov theory and input-to-state stability (ISS). Compared to the previous related works, our main contribution is that the proposed adaptive control strategy is fully distributed and scalable, which is independent any global information of the network graph and is independent of the UHs's scale and we proved the stability of the closed-loop. Finally, the effectiveness and superiority of the designed strategy are demonstrated by numerical simulations.