Design of autopilot for fixed wing unmanned aerial vehicle using sliding mode controller

Recently, there is an interest over unmanned aerial vehicles (UAVs) that prevent possible military personel dead in accident in military field and the interest is going to increase gradually by adding new features to UAVs. Because of that, the absence of human factor in UAV systems, a control mechanism requirement becomes a necessity. Furthermore, even in some cases under human control, because of the human limitations that physiological features such as tolerance to high pressure and extreme forces, an auxiliary control structure is required. At this point, in the literature there are many control theories and these have superiotries among themselves around some point. The system that we work on aims at having robust system structure under possible parameter and environmental changes. These factors necesitates a control system structure requirement with sliding mode control that is a member of the robust controller family. Conventional sliding mode controller design has some restrictions in terms of system type and requires all state variables of the system to be measurable. In this study, to overcome these limitations and generation the control signals by using only the output signals of the system instead of measuring all of the state variables of the system, Dynamic Output Feedback Sliding Mode Controller is designed. The controller is designed in Matlab/SIMULINK environment. Obtained controller performance is tested both software in loop simulations in Xplane flight simulator which is a detailed flight simulator to test the extreme flight conditions and in real flight tests designed for Apprentice-S model aircraft with Ardupilot controller board.