Design and Flight Control of Tail-Sitter Uncrewed Aerial Vehicles: A Review

One of the most promising uncrewed aerial vehicles (UAVs), tail-sitter UAVs combine the long endurance of fixed-wing aircraft with the vertical takeoff and landing capabilities of rotary-wing aircraft. This versatility has driven significant research interest over the past decade. However, a comprehensive overview of their development remains lacking. This article presents a comprehensive review of tail-sitter UAVs from a mechatronics perspective, emphasizing their integrated design and flight control technologies. Based on actuator integration methods, tail-sitter UAVs are classified into five types: single rotor (with or without thrust-vectoring), dual rotor (coaxial and parallel), quadrotor (monoplane and biplane), ducted fan, and others. The advantages and limitations of each type are analyzed. Flight control remains a primary challenge for tail-sitter UAVs due to highly variable flight speeds and strongly coupled dynamics during transition maneuvers. Therefore, flight control techniques are systematically reviewed from four aspects: dynamic characteristics analysis, flight corridor development, transition trajectory design, and controller design. Finally, current research gaps and future directions are discussed, particularly in distributed propulsion, hybrid electric systems, autonomous flight, and other areas. The insights provided herein aim to systematically guide future research on tail-sitter UAVs, facilitating their integration into diverse industrial applications.