Disturbance observer-based control for small nonlinear UAV systems with transient performance constraint

Abstract

Small UAVs are a class of nonlinear systems with unknown dynamics and uncertainties. This paper proposes a disturbance observer-based (DOB) control scheme with transient performance design for such small UAV systems. In order to strictly guarantee both steady-state and transient observation performance, the idea of prescribed performance function (PPF) is incorporated into the disturbance observer design by transforming an estimation problem into a control problem. Then by utilizing backstepping technique to design the certain part of UAVs, virtual control is updated to compensate the mismatched items of the observed disturbances, where system stability is rigorously proved. Finally, comparative simulations with nonlinear UAV systems are conducted to validate the improved response and the robustness of the proposed control method.