V3Hiculos Aereos No Tripulados

Hover to Cruise Flight of a Tailsitter Mini-UAV: Modeling, Control and Implementation
J. Escareño, S. Salazar, G. Flores
Laboratorio Franco-Mexicano de Informatica y Automatica UMI-CNRS 3175 CINVESTAV, Mexico City Email: jescareno@ctrl.cinvestav.mx Email: ssalazar@ctrl.cinvestav.mx Email: gflores@ctrl.cinvestav.mx

R. Hugh Stone
Military Aircraft Business Unit Australian Aerospace Ltd RAAFBase Richmond, NSW Email: hstone@ausaero.com.au

R. Lozano
Laboratorio Franco-Mexicano de Informatica y Automatica UMI-CNRS 3175 CINVESTAV, Mexico City Email: rlozano@ctrl.cinvestav

Abstract—This paper addresses the problem of the transition between rotary-wing and fixed-wing flight of a tail-sitter mini unmanned aerial vehicle (mUAV). A control strategy is presented to control, via nonlinearcontroller, the vertical and horizontal flight dynamics of the vehicle in the longitudinal plane. We present the dynamic and aerodynamic equations that model the behavior of the vehicle in the whole flight envelope. An experimental prototype is developed to perform the vertical, transition and forward light, obtaining satisfactory results. A low-cost DSP-based embedded control system is designed andbuilt to control the autonomous attitude-stabilized flight during the experimental flight. Index Terms—Tail-sitter UAV, Operational Transition, Innerouter loop control, Embedded Control System

I. INTRODUCTION The applications of mini Unmanned Aerial Vehicles (UAVs) have widely diversified during the last years. They comprise both military and civilian, though the latter has had a lower developmentrate. The key feature of UAVs is to provide a mobile extension of human perceptions allowing not only the security of the user (soldier, policeman, cameraman, volcanologist) but also gathering information such as images or video, locations coordinates, weather conditions, etc., for either online or offline analysis. As a result, the use of aerial robots, specially small UAVs, mini and micro UAVs(mUAVs, MAVs), has enhanced activities such as surveillance of sensible areas (ports, borders, prisons), wildlife study, natural disasters assessment, traffic surveillance, pollution monitoring, just to mention a few. However, there are missions whose scope is beyond the capabilities of conventional small UAVs designs since they require not only longer flight endurance but also hovering/VTOL1capabilities. Missions like the surveillance of fast-moving/static targets, medical supplies (blood samples, saliva samples, medications) exchange between hospitals and clinics located in remote areas, identification of cracks in pipelines or bridges. This poses the necessity of vehicles capable of maneuvering in more than one operational profile, i.e. the combination of rotary and fixed wing configurations.1 Vertical

Take-off & Landing

Tail-sitter UAVs have a number of advantages compared to other configurations. In comparison to conventional designs they offer a large operational flexibility because they don’t require a runway for take-off and landing but instead can operate from any small clear space. While other conventional designs partially overcome this limitation via the use of takeoffand landing aids such as catapults and parachutes, these all entail extra system complexity and logistic support. Although helicopter UAVs share the same operational flexibility as the tail-sitter, they suffer from well known deficiencies in terms of range, endurance and forward speed limitations due to the lower efficiency of rotor-born, rather than wing-born flight. Lastly, the other configurationswhich have been developed to achieve the same goals as the tail-sitter, such as the tilt-wing, tilt-rotor and tilt-body, do so at the expense of significantly increased mechanical complexity compared to a tail-sitter that uses propeller wash over normal aircraft control surfaces to perform vertical flight. By marrying the takeoff and landing capabilities of the helicopter with the forward flight...