Nonlinear hierarchical adaptive control of a quad tilt-wing UAV

Official URL: http://risc01.sabanciuniv.edu/record=b1615037 (Table of Contents)

Unmanned aerial vehicles (UAVs) have become an indispensable part of many military and civilian applications. The popularity of these vehicles have led to a demand for novel mechanical con gurations and controllers which are adaptable for the requirements of the desired tasks. In this thesis, a nonlinear hierarchical adaptive controller is proposed for the control of a quad tilt-wing unmanned aerial vehicle (SUAVI: Sabanci University Unmanned Aerial Vehicle). SUAVI can take-o vertically as a helicopter and ies like a xed-wing airplane during the long duration ights for power e ciency. In order to compensate for the uncertainties such as moment of inertia changes during the transition from vertical mode to horizontal mode and aerodynamic disturbances an adaptive controller framework is proposed. In the outer loop of the hierarchical control, a model reference adaptive controller with robustifying terms creates required forces to track the reference trajectory and in the inner loop a nonlinear adaptive controller tracks the desired attitude angles to achieve these forces. The proposed controller is applied to a high delity UAV model in the presence of uncertainties, wind disturbances and measurement noise. A structural failure is introduced which results in sudden actuator power drops, mass, inertia and center of gravity changes. Performance of the proposed controller is compared with the feedback linearized xed controller used in earlier studies.