Carrier differential GPS as a sensor for automatic control: Development of a full state estimation and flight control system for an autonomous aircraft based on the global positioning system

This thesis is about the use of the Global Positioning System (GPS) as a sensor for automatic control. To control a vehicle outdoors in an uncontrolled (non-laboratory) environment, information on orientation and position is needed. Automotive or agricultural vehicles, aircraft and ships are potential mobile examples. Cranes and derricks are potential machine examples. To achieve control, the ability to sense position and orientation accurately, robustly and reliably is paramount.; The vehicle investigated here is a small, highly maneuverable, autonomous aircraft. Having three degrees of position and three degrees of orientation freedom, it provides a challenging and suitably general platform on which to demonstrate the concept.; The thesis describes the construction, modeling, hardware and algorithms that were employed to make a 12 foot autonomous aircraft fly a predetermined trajectory (from takeoff to landing) without any form of inertial instrumentation or human intervention. To the knowledge of the author, this is also the first time such capability has been demonstrated.; The thesis also includes a chapter on the integration of inexpensive piezo-electric rate gyroscopes with GPS attitude measurements. In simulation it is shown that this form of sensor fusion can improve attitude robustness, accuracy and bandwidth relative to a system using either sensor in isolation.