Design And Implementation Of Attitude Measurement System Based On GPS

As a new generation of satellite positioning navigation system the Global Positioning System is famous for its high precision, global character, all-weather, continuity and high speed, It can overcome inertial navigation equipment's shortcoming which error accumulates along with the time effectively. With the rapid development of the carrier phase differencing technique and digital signal processing hardware,The research on attitude determination by GPS carrier phase differencing measurement explores a new area in GPS application. This thesis investigates the attitude determination using carrier phase differencing technique with an emphasis on theoretical aspects and algorithms of the attitude determination and the solution of integer ambiguity. The implementation of GPS determination system based on FPGA is also discussed.The GPS attitude determination system which is discussed in this thesis consists of four vital parts including data acquisition and processing, integer ambiguity determination, attitude determination and the hardware implementation of the GPS attitude determination system. In the first part the configuration information has to be send into the GPS receiver firstly, then the binary information received from the GPS receiver needs to be extracted and converted in format. The integer ambiguity determination is discussed in the second part, the method of QR decomposition algorithm will be used in the ambiguity determination because of its rapidity, we can determinate the integer ambiguity form the scope of the integer ambiguity with the help of constraints. The attitude determination is discussed in the third part, and the carrier phase difference model which comes form the carrier phase observation equation will be established by using the differential techniques, the vector solution of the baseline and the angles of the attitude will be acquired from the model. In the last part the implementation of hardware and software which based on the research in the first three parts will be discussed. This GPS attitude determination system takes the FPGA as the hardware foundation, Nios II soft-core as the processor, and two SUPERSTAR II GPS OEM boards as the GPS signal receivers. Finally, this system will be verified by a variety of experimental programs, and it can be proved that the plan is feasible, the system works well, and the attitude angles can be acquired effectively.