4,555 research outputs found

    Pitch-Efficient Trajectory Tracking for Winged eVTOL UAVs

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    Current control methods for winged eVTOL UAVs consider the vehicle primarily as a fixed-wing aircraft with the addition of vertical thrust used only during takeoff and landing. These methods provide good long-range flight handling but fail to consider the full dynamics of the vehicle for tracking complex trajectories. We present a trajectory tracking controller for the full dynamics of a winged eVTOL UAV in hover, fixed-wing, and partially transitioned flight scenarios. We show that in low-to moderate-speed flight, trajectory tracking can be achieved using a variety of pitch angles. In these conditions, the pitch of the vehicle is a free variable which we use to minimize the necessary thrust, and therefore energy consumption, of the vehicle. We use a geometric attitude controller and an airspeed-dependent control allocation scheme to operate the vehicle at a wide range of airspeeds, flight path angles, and angles of attack. We provide simulation results and theoretical guarantees for the stability of the proposed control scheme assuming a standard aerodynamic model

    Solar UAV for long endurance flights

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    The project have been done during the four months stay in Lithuania by Marc Olmo and LLibert Chamizo. The aim of the project was to obtain an Unmanned Aerial Vehicle powered by solar energy that was able to flight for as long as possible it within the limitations which are the budget, the time and the technological limitations. During the limited time, the team have been working in all the necessary phases to build a real scale and fully functional Solar UAV. This phases were the following; Theoretical Calculations, Design, Simulation, Building, Tests of the Airframe, Solar Energy Circuit Design and Building 2nd phase tests and Conclusion Obtaining. Through all the process several technical and engineering decisions have been made leading the team to obtain a fully functional 4,4m wingspan fixed wing UAV with a TOW of 5,5 Kg which is perfectly pilotable The final achievements have been a UAV capable of long endurance flight within daytime. The model achieved was able to maintain level, climb and turn perfectly using just the power gathered by the solar cells in its wing. During the development of the project the possibility of the multiday flight have been discussed leading to the conclusion that it's viable but not within the frame of this project. There have been done several tests under actual mission parameters loading the plane with the weight it would be carried during the missions that are most likely solar uav related such as mapping or surveillance. The final result have been correct and lead to an optimistic opinion about the whole Solar UAV paradigm and about the prototype modification and improvement in the near future to achieve even better results (which have been overviewed and planned in the actual report). A fatal error drove the airplane to a nosedive fall with disastrous consequences, the whole project feels and success though it's undoubtable

    Design, simulation and analysis of a parallel hybrid electric propulsion system for unmanned aerial vehicles

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    Aerial Vehicles (UAV) has become a significant growing segment of the global aviation industry. These vehicles are developed with the intention of operating in regions where the presence of onboard human pilots is either too risky or unnecessary. Their popularity with both the military and civilian sectors have seen the use of UAVs in a diverse range of applications, from reconnaissance and surveillance tasks for the military, to civilian uses such as aid relief and monitoring tasks. Efficient energy utilisation on an UAV is essential to its functioning, often to achieve the operational goals of range, endurance and other specific mission requirements. Due to the limitations of the space available and the mass budget on the UAV, it is often a delicate balance between the onboard energy available (i.e. fuel) and achieving the operational goals. This paper presents the development of a parallel Hybrid Electric Propulsion System (HEPS) on a small fixed-wing UAV incorporating an Ideal Operating Line (IOL) control strategy. A simulation model of an UAV was developed in the MATLAB Simulink environment, utilising the AeroSim Blockset and the in-built Aerosonde UAV block and its parameters. An IOL analysis of an Aerosonde engine was performed, and the most efficient (i.e. provides greatest torque output at the least fuel consumption) points of operation for this engine were determined. Simulation models of the components in a HEPS were designed and constructed in the MATLAB Simulink environment. It was demonstrated through simulation that an UAV with the current HEPS configuration was capable of achieving a fuel saving of 6.5%, compared to the ICE-only configuration. These components form the basis for the development of a complete simulation model of a Hybrid-Electric UAV (HEUAV)

    On the trade-off between electrical power consumption and flight performance in fixed-wing UAV autopilots

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    This paper sets out a study of the autopilot design for fixed wing Unmanned Aerial Vehicles (UAVs) taking into account the aircraft stability, as well as the power consumption as a function of the selected control strategy. To provide some generality to the outcomes of this study, construction of a reference small-UAV model, based on averaging the main aircraft defining parameters, is proposed. Using such a reference model of small, fixed-wing UAVs, different control strategies are assessed, especially with a view towards enlarging the controllers' sampling time. A beneficial consequence of this sample time enlargement is that the clock rate of the UAV autopilots may be proportionally reduced. This reduction in turn leads directly to decreased electrical power consumption. Such energy saving becomes proportionally relevant as the size and power of the UAV decrease, with benefits of lengthening battery life and, therefore, the flight endurance. Additionally, through the averaged model, which is derived from both published data and computations made from actual data captured from real UAVs, it is shown that behavior predictions beyond that of any particular UAV model may be extrapolated.Peer ReviewedPostprint (author's final draft
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