Browsing by Author "Sanches, Tiago Nunes"
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- Longitudinal flight control with a variable span morphing wingPublication . Sanches, Tiago Nunes; Bousson, Kouamana; Gamboa, Pedro VieiraThe present study focuses on the design of a longitudinal flight controller for an unmanned aircraft equipped with dissymmetric variable-span system (VSMW or Variable-Span Morphing Wing). Its primary role consists in the longitudinal flight stabilization of the aeroplane while in levelled cruise flight, although, it was designed to offer longitudinal flight stabilization for other flight phases as well, such as e.g. take-off and landing. The stabilization algorithm relies on the most up-to-date developments in the state-of-the-art LQR and Batz-Kleinman controller techniques to stabilize the aircraft on its intended longitudinal attitude upon any small atmospheric disturbances inflicted. It was designed for the experimental UAV prototype Olharapo equipped with the VSMW, so it can automatically adjust the VSMW overall wingspan in accordance with the flight speed and stabilize the aircraft in the desired attitude, although, its modular concept allows it to be used for different configurations of the aircraft or even for a different aircraft. The development, simulation and testing of the algorithm were done using the MATLAB® software and the aircraft’s stability and control derivatives previously obtained using the XFLR5® software. Minor adaptations of the flight dynamics equations were performed to allow the compatibilization with the VSMW. The required implementation of imposed flight qualities was also performed to ensure proper scaling the controller weight matrix for optimal values. Finally, the algorithm was tested using three different methods: Classic Disturbances Simulation, Sinusoidal Pitch Variation Test Response and Random Pitch Variation Test Response.
- Optimal Robust Nonlinear LQG/LTR Control with Application to Longitudinal Flight ControlPublication . Sanches, Tiago Nunes; Bousson, K.As part of the development of a new 4D Autopilot System for Unmanned Aerial Aircrafts (UAVs), i.e. a time-dependent robust trajectory generation and control algorithm, this work addresses the problem of optimal path finding based on the aircraft’s own sensors data output, that may be unreliable due to noise on data acquisition and/or transmission under certain circumstances. Although several filtering methods, such as the Kalman-Bucy Filter or the LQG/LTR, are available, the utter complexity of the new control system, together with the robustness and reliability required of such a system on an UAV for airworthiness certifiable autonomous flight, required the development of a proper robust filter for a nonlinear system, as a way of further mitigate errors propagation to the control system and improve its performance. As such, a new nonlinear LQG/LTR algorithm, validated through computational simulation testing, is proposed on this paper. This research work was conducted in the Laboratory of Avionics and Control of the Department of Aerospace Sciences (DCA) at the Faculty of Engineering of the University of Beira Interior and supported by the Aeronautics and Astronautics Research Group (AeroG) of the Associated Laboratory for Energy, Transports and Aeronautics (LAETA).