Autonomous control of an unstable model helicopter using carrier phase gps only

This thesis contains the results of my experiments in using carrier phase global positioning system (GPS) techniques to totally control an inherently unstable model helicopter for the first time. In the process a new algorithm for determining the unknown integer wavelength offsets for attitude calculation was devised. The helicopter is capable of hovering autonomously. It uses four GPS antennas on the helicopter and a ground reference station to determine position and attitude to precisions of roughly a centimetre and a degree, both at a ten Hertz update rate. The new algorithm for integer resolution allows integers to be resolved in a computationally efficient manner with fewer satellites in view than previous algorithms, allowing use in a greater number of applications. This thesis describes the overall problems, approaches, and philosophy of design, then contains detailed descriptions of the various logical parts of the project. A description is given of GPS, carrier phase approaches, and how position, velocity, attitude and attitude rate can be calculated, and a description of the new algorithms that make this possible. The hardware used in this project is then described, followed by the software for flight and analysis. The results of the flight tests are given, and then some conclusions and suggestions for further work in this valuable arena are presented. The appendices contain comprehensive technical details of the hardware and software.