Adaptif dört rotorlu bir insansız hava aracının modellenmesi ve kontrolü

In the last years there is a drastic increase of demand on the unmanned aerial vehicles (UAVs). The UAVs are commonly used in military, scientific and civilian sectors where they are giving better results in surveillance & rescue missions and missions that take place in danger zones such as nuclear plants and battle fields. UAVs are often preffered due to their higher maneuverability, decreased radar signature, lower cost in long run, durability, as well as decreased risk for human life. That's why vast researchers studying on UAVs are currently focusing to increase the abilities of these aircrafts. Among the UAV world, vertical take off and landing (VTOL) units are also in a favorable position as there is almost no need for an extra landing field and airfield for take off and landing. As being one of the versions of VTOL units, quadrotor is a UAV platform in which there exists four rotors and propellers to create the necessary thrust force in order to enable the vehicle's flight and determine the 3D position of its flight direction. However, as being an underactuated system, there is a limiting factor for the way quadrotor move. It is necessary to tilt the body frame along the desired direction of motion in order to change the 3D coordinates of the vehicle. Tilting the body frame can result with some undesired effects when the work area is limited and/or when there is a need to use of on-board cameras or sensors. There are already some studies on tiltable rotor design for planes which are able to tilt their rotors only in one direction, enhancing an extra one degree of freedom for the rotor in question. This kind of a design improves the maneuverability such that the aircraft can switch from plane mode to helicopter mode by the transition of the tilting rotors. Moreover, there are advantages on the increase of the distribution of required force vectors by transfering and delivering the thrust force along the desired axes. There are a few studies that have tiltable geometry for unmanned quadrotors and other VTOL units. However, their rotor tilting mechanisms are all limited along the one axis only. In these studies, rotors tilt either all at the same time at same direction with a pre-specified amount, or all tilt around one axis only. Unlike the regular design, this study proposes an alternative propulsion system for quadrotors. The rotors of the quadrotor both have tilting and rolling capabilities around their axes adding 8 additional control inputs. Hence, upgrading the system being underactuated to overactuated. In the first part of this study all the rotors are controlled such that they have the same tilt-roll angles depending on each other. After the tilt-roll capable system is designed and verified via Matlab simulations, further failure modes of the rotors, propellers xx and outside environmental effects are added as a random noise signal. Then the system is controlled and balanced by driving each of the rotors' tilt-roll angles independently from each other. It is introduced in adaptive control of tilt-roll rotor quadrotor sections of this thesis. The proposed design in this paper has more complex but more effective control system and algorithm with respect to the previous studies and regular quadrotors. What's more the possible failure modes of the system is analysed and some preventive-safe flight actions and further adaptive control systems in order to compensate for these failure modes are presented. This design eliminates the need of tilting the body frame, what's more it has relatively better performance in terms of lower reach, settling time and maximum overshoot values when travelling along 3D coordinates. The mathematical model of the tiltable-rotor type quadrotor and designed control algorithms are studied during the development stages of this work. The detailed explanation of the mathematical model, control system design and algorithm will be introduced in the following pages. In order to verify the results various simulations are developed on MATLAB and Simulink. Comparison of the proposed system performances are better than what a regular quadrotor suggests.