Nonlinear control of a quad tilt-wing UAV

Official URL: http://192.168.1.20/record=b1379250 (Table of Contents)

Unmanned aerial vehicles (UAVs) have become increasingly more popular over the last few decades. Their fascinating capabilities and performance in accomplishing a specific task have made them indispensable for various civilian/commercial and military applications. The remarkable progress in advanced manufacturing techniques and electronic components have rendered development of small, intelligent and low-cost UAVs possible. Consequently, a significant amount of research effort has been devoted to design of UAVs with intelligent navigation and control systems. This thesis work focuses on nonlinear control of a quad tilt-wing unmanned aerial vehicle (SUAVI: Sabanci University Unmanned Aerial Vehicle). The aerial vehicle has the capability of vertical takeoff and landing (VTOL), and flying horizontally due to its tilt-wing mechanism. Nonlinear dynamical models for various flight modes are obtained. A hierarchical control system that includes vertical, transition and horizontal modes flight controllers is developed. In order to design these controllers, the dynamics of the aerial vehicle is divided into position and attitude subsystems. Several nonlinear position control methods are developed for different flight modes. For the vertical flight mode, integral sliding mode and PID based position controllers via dynamic inversion method are designed. Feedback linearization and integral sliding mode attitude controllers are also proposed for the attitude stabilization of the aerial vehicle in vertical, transition and horizontal flight modes. Simulations and several real flight experiments demonstrate success of the developed flight controllers.