Dynamics Modeling and Full-Phase Control of a Z-Folding VTOL Aircraft

This paper focuses on modeling and control of a Z-folding vertical takeoff and landing (VTOL) aircraft, which integrates the maneuverability of quadrotors with the efficiency of fixed-wing platforms. For modeling, the strip theory is employed to compute aerodynamic forces and moments. The aircraft is decomposed into three rigid components: left outer wing, right outer wing, and inner wing. By calculating the moment of inertia for each component individually and superimposing the results, the total moment of inertia associated with the folding angle is derived. A multi-rigid-body dynamic model is formulated using Newton-Euler equations to capture the coupled dynamics during morphing. For control, a comprehensive full-process control strategy is developed to address the three operational modes (quadrotor, morphing, fixed-wing) and their corresponding transition phases within the full flight envelope. Numerical simulations validate that this strategy enables seamless mode transitions and maintains precise position/attitude tracking across all flight phases, thus demonstrating the efficacy of the proposed modeling and control approaches.