Redundant autopilot systems for fixed wing uav

Unmanned aerial vehicles have played a major role in the defense strategies of the last centuries with the innovations it has brought since the first day they were used. This unmanned aerial vehicles are used in many different military and civilian fields.. Especially with the disappearance of the human factor, the prevention of human losses in possible accidents has aroused interest and curiosity in the studies. These autonomous vehicles, whose crews have been replaced by a computer system and have a wireless data line, are less costly than manned aerial vehicles, and also more tolerant to dangerous and harsh maneuvers. With the elimination of the human factor, there is a need for a control mechanism within the aerial vehicles. There are many different control theories in the literature. In this study, autopilot system designed using floating mode controller, which is a kind of robust control, is backed up and performance analysis is performed in MATLAB / SIMULINK environment with the voter algorithm integrated into the system. Redundant autopilot systems duplicate the autopilot hardware in the system and mask any errors that may occur in the autopilot. These analyzes were made considering three redundant autopilot systems. The analyzes are; analysis of non-redundant and correctly operating autopilot behavior, redundant system - analysis of behavior in which all three autopilots are operating correctly, analysis of non redundant and autopilot operating in the faulty state, analysis of any autopilot operating in the faulty state, analysis of behavior of two autopilot operating in the faulty state, analysis of behavior in the case of minor disturbances in all three autopilots. In these analyzes, it is shown that the stability of the system cannot be maintained and flight safety cannot be ensured in case of any error that may occur in autopilot at non-redundant autopilot systems. Therefore, in order to demonstrate the necessity of redundant autopilot systems and to ensure flight safety with an optimum safety - cost ratio, the following results are summarized in the safety analysis of three redundant autopilot systems. In the redundant systems, even if two autopilot systems fail, or a small level of error occurs at three autopilots, it is shown that the stability of the system for fixed wing unmanned aerial vehicles is non deteriorated and flight safety is ensured thanks to the coherent working of the voter algorithm with redundant autopilot systems. As a result of the analysis, it was seen that autopilot redundancy increases flight reliability. If the cost of failure of a system causes property and life losses in possible accidents, the system should be redundant to increase its reliability. The algorithm used in redundant systems can be implemented in any type of controller. The analyzes have been made considering the scenario of loss of rudder control which is a common failure. Keywords: N modular redundancy systems , Voter algorithms, Redundant systems, Unmanned aerial vehicles, Triple modular redundancy, Matlab/SIMULINK