Nonlinear modeling and flight control system design of an unmanned aerial vehicle

Karakaş, Deniz
The nonlinear simulation model of an unmanned aerial vehicle (UAV) in MATLAB®/Simulink® environment is developed by taking into consideration all the possible major system components such as actuators, gravity, engine, atmosphere, wind-turbulence models, as well as the aerodynamics components in the 6 DOF equations of motion. Trim and linearization of the developed nonlinear model are accomplished and various related analyses are carried out. The model is validated by comparing with a similar UAV data in terms of open loop dynamic stability characteristics. Using two main approaches; namely, classical and optimal, linear controllers are designed. For the classical approach, Simulink Response Optimization (SRO) tool of MATLAB®/Simulink® is utilized, whereas for the optimal controller approach, linear quadratic (LQ) controller design method is implemented, again by the help of the tools put forth by MATLAB®. The controllers are designed for control of roll, heading, coordinated turn, flight path, pitch, altitude, and airspeed, i.e., for the achievement of all low-level control functions. These linear controllers are integrated into the nonlinear model, by carrying out gain scheduling with respect to airspeed and altitude, controller input linearization regarding the perturbed states and control inputs, and anti integral wind-up scheme regarding the possible wind-up of the integrators in the controller structures. The responses of the nonlinear model controlled with the two controllers are compared based on the military flight control requirements. The advantages and disadvantages of these two frequently used controllers in industry are investigated and discussed. These results are to be evaluated by the designers themselves based on the design criteria of a project that is worked on.


Multidisciplinary design of an unmanned aerial vehicle wing
Sakarya, Arzu; Yaman, Yavuz; Department of Aerospace Engineering (2011)
In this thesis, the structural design, structural analysis and producibility analysis of an unmanned aerial vehicle wing were performed. Three different wing models, made of different materials, were designed. The wings were aluminum wing model and composite wing models; made of prepreg and wet lay-up. All wings have the same aerodynamic geometry and structural configuration under the same flight conditions. The structural designs of three wings were done by using Unigraphics NX. The finite element modeling...
Structural optimization of a composite wing
Sökmen, Özlem; Akgün, Mehmet A.; Department of Aerospace Engineering (2006)
In this study, the structural optimization of a cruise missile wing is accomplished for the aerodynamic loads for four different flight conditions. The flight conditions correspond to the corner points of the V-n diagram. The structural analysis and optimization is performed using the ANSYS finite element program. In order to construct the flight envelope and to find the pressure distribution in each flight condition, FASTRAN Computational Fluid Dynamics program is used. The structural optimization is perfo...
Low reynolds number aerodynamics of flapping airfoils in hover and forward flight
Günaydınoğlu, Erkan; Kurtuluş, Dilek Funda; Department of Aerospace Engineering (2010)
The scope of the thesis is to numerically investigate the aerodynamics of flapping airfoils in hover and forward flight. The flowfields around flapping airfoils are computed by solving the governing equations on moving and/or deforming grids. The effects of Reynolds number, reduced frequency and airfoil geometry on unsteady aerodynamics of flapping airfoils undergoing pure plunge and combined pitch-plunge motions in forward flight are investigated. It is observed that dynamic stall of the airfoil is the mai...
Development of a dynamic flight model of a jet trainer aircraft
Gilani, Muhaned; Özgen, Serkan; Department of Aerospace Engineering (2007)
A dynamic flight model of a jet trainer aircraft is developed in MATLAB-SIMULINK. Using a six degree of freedom mathematical model, non-linear simulation is used to observe the longitudinal and lateral-directional motions of the aircraft following a pilot input. The mathematical model is in state-space form and uses aircraft stability and control derivatives calculated from the aircraft geometric and aerodynamic characteristics. The simulation takes the changes in speed and altitude into consideration due t...
Multidisciplinary and multiobjective design optimization of an unmanned combat aerial vehicle (UCAV)
Çavuş, Nesrin; Tekinalp, Ozan; Department of Aerospace Engineering (2009)
The Multiple Cooling Multi-Objective Simulated Annealing Algorithm is used for the conceptual design optimization of a supersonic Unmanned Combat Aerial Vehicle (UCAV). Single and multiobjective optimization problems are addressed while limiting performance requirements between desired bounds to obtain viable aircraft configurations. A conceptual aircraft design code was prepared for planned but flexible combat missions. The results demonstrate that the optimization technique employed is an effective tool f...
Citation Formats
D. Karakaş, “Nonlinear modeling and flight control system design of an unmanned aerial vehicle,” M.S. - Master of Science, Middle East Technical University, 2007.