Ertuğrul Çetinsoy

This paper presents a robust position controller for a tilt-wing quadrotor to track desired traje... more This paper presents a robust position controller for a tilt-wing quadrotor to track desired trajectories under external wind and aerodynamic disturbances. Wind effects are modeled using Dryden model and are included in the dynamic model of the vehicle. Robust position control is achieved by introducing a disturbance observer which estimates the total disturbance acting on the system. In the design of the disturbance observer, the nonlinear terms which appear in the dynamics of the aerial vehicle are also treated as disturbances and included in the total disturbance. Utilization of the disturbance observer implies a linear model with nominal parameters. Since the resulting dynamics are linear, only PID type simple controllers are designed for position and attitude control. Simulations and experimental results show that the performance of the observer based position control system is quite satisfactory.

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Design and construction of a novel quad tilt-wing UAV

Mechatronics, 2012

ABSTRACT This paper presents aerodynamic and mechanical design, prototyping and flight control sy... more ABSTRACT This paper presents aerodynamic and mechanical design, prototyping and flight control system design of a new unmanned aerial vehicle SUAVI (Sabanci University Unmanned Aerial VehIcle). SUAVI is an electric powered quad tilt-wing UAV that is capable of vertical takeoff and landing (VTOL) like a helicopter and long duration horizontal flight like an airplane. Aerodynamic and mechanical designs are optimized to enhance the operational performance of the aerial vehicle. Both of them have great importance for increasing efficiency, reaching the flight duration goals and achieving the desired tasks. A full dynamical model is derived by utilizing Newton–Euler formulation for the development of the flight control system. The prototype is constructed from carbon composite material. A hierarchical control system is designed where a high level controller (supervisor) is responsible for task decision, monitoring states of the vehicle, generating references for low level controllers, etc. and several low level controllers are responsible for attitude and altitude stabilization. Results of several simulations and real flight tests are provided along with flight data to show performance of the developed UAV.

Aerodynamic Design and Characterization of a Quad Tilt-Wing UAV via Wind Tunnel Tests

Journal of Aerospace Engineering, 2012

ABSTRACT This paper presents aerodynamic design and characterization of a new quad tilt-wing unma... more ABSTRACT This paper presents aerodynamic design and characterization of a new quad tilt-wing unmanned aerial vehicle [Sabanci University unmanned aerial vehicle (SUAVI)] through wind tunnel tests and provides experimental data for the design of similar aerial platforms. SUAVI is capable of vertical takeoff and landing (VTOL) and horizontal flight, and it can perform both indoor and outdoor surveillance. Aerodynamic design of the vehicle directly affects its operational performance, including flight stability and flight duration in vertical, transition, and horizontal flight modes. Selection of the propulsion system and determination of the shape of the fuselage and the wings are done in an optimal manner by taking several aerodynamic criteria into account. Flow simulations reveal that the rear wings are affected by the downwash of the front wings. To solve this problem, the rear wings are placed at a higher incidence angle than the front wings. Wind tunnel tests are performed to measure the lift and drag forces and pitching moments for level flight in the entire speed range. Furthermore, the rear and front motor throttle settings and the wing incidence angle combinations for the nominal flight are measured and tabulated. To eliminate undesired spanwise air flows at the wing tips, several winglets with different shapes and sizes are introduced, and the optimum winglet is developed by several simulations and experiments. Some of the results presented in this paper are novel contributions to the literature and can be used in the design of new hybrid unmanned aerial vehicles (UAVs). DOI: 10.1061/(ASCE)AS.1943-5525.0000161. (C) 2012 American Society of Civil Engineers.