flight mechanics and control of tilt rotor/tilt wing unmanned aerial vehicles: a review

A literature review of the tilt rotor/tilt wing (tr/tw) unmanned aerial vehicles (uavs) is presented in this paper from the flight mechanics and control points of view. firstly, the advantages as well as the challenges of the tr/tw uavs are studied, from the design, aerodynamic, flight dynamic and control viewpoints. next, a chronicle of the most important researches conducted about the tr/tw uavs is reported. then, these tr/tw uavs are categorized based on the overall configurations, rotor arrangements, engine/rotor positions, and engine/rotor types. next, a comprehensive flight dynamic modeling of the tr/tw aircraft is introduced that may provide a complete and consistent set of the dynamic equations for any type of the tr/tw regardless of the configurations and rotor arrangements. afterwards, a survey is carried out about the trim and stability of the tr/tw within the hover and transition phases of flight. finally, different control methods and control strategies utilized for the attitude and altitude control of the tr/tw uavs are categorized based on their pros and cons. since this paper covers the flight mechanics and control of the tr/tw uavs, it may assist designers in making decisions about the most critical aspects of a new design based on the previous studies.