Development of a fixed wing UAV reference model for studies of autopilots simulations

The use of Unmanned Aerial Vehicles and their applications are increasing every day. Those vehicles are in certain way autonomous, so they need to have a well studied and defined autopilot. In order to study autopilots it is necessary to have a dynamic model that represents how would be the behaviour of the aircarft in a real situation. However, there is a high dispersion on the use of these models. Usually, papers and articles about autopilots' studies can be found in the literature, but all of them use an own model that have been defined exclusively for the corresponding UAV they are using. Due to that, this project has the aim to construct a reference model that could be used in studies of autopilots and control techniques, non-depending on the considered UAV. Evidently, there are a lot of types of different UAVs, so it would have no sense to try to construct a model useful for a multirotor and a fixed wing aircraft at the same time. By the way, the scope of the project has been reduced to fixed wing UAVs of about 3 meters of wingspan. Moreover, regarding the three types of stability that can be differentiated in an aircraft (longitudinal, lateral and directional), only the longitudinal stability has been considered. It is the one that has more presence in the literature and it might be the more representative concerning the whole behaviour of the UAV. The goal of the project is to take into account different fixed wing unmanned aerial vehicles and compute an averaged model of all of them. Those individual models have been achieved from two different sources of information. On the one hand, articles, papers, books and other written documents have been consulted obtaining models already defined. On the other hand, some models have been created purposely for the project with the help of Digital Datcom. Due to the existing dispersion in the variables the found models use and the different ways in which they have been constructed, the most feasible way to average all of them has been considering their pole-zero diagrams. Finally, using the reference model created, it has been done a study to find out what are the structural parameters that more affect the stability of the UAV. This study joined to the reference model can be useful to make lighter the process of constructing a model before starting any study of autopilots. In addition, when designing the aircraft, they can be even useful to decide how each parameter should be in terms of stability.