Improved Observer-based Fully Actuated System Approach to 3-DOF Quadrotor Control

Conventional state-space method cannot effectively address the strong coupling, nonlinearity, and underactuation characteristics inherent in quadrotor unmanned aerial vehicle (QUAV) systems. Therefore, based on the fully actuated system approach (FASA) proposed by Duan, this paper innovatively explores an improved observer-based FASA to 3-DOF quadrotor control. We derive an equivalent FAS of the UAV's physical dynamics and further develop a novel input calculation method for controller design without the need for an extended state observer (ESO) to estimate inputs and their derivatives, and a Luenburger observer is applied to estimate the unmeasurable states. The proposed approach compensates for the inherent nonlinearities of the original system, allows arbitrary assignment of desired closed-loop eigenstructure to achieve stabilization and tracking control, and significantly reduces computational complexity, which is crucial for real-time control systems. Finally, the simulation results validate the effectiveness of the proposed method.