Rapid Gps Attitude Determination Technology Research

The Global Positioning System (GPS) is poised to revolutionize flight vehicle Guidance, navigation, and Control. The technology of determining attitude of carrier by GPS carrier phase measurements is becoming a particle of navigation fields because of its high precision and its freedom from the constraints of Precise Code (or Y code) by the U.S.Real-time attitude determination is derived from extremely precise differential carrier phase measurements among multiple GPS antennas mounted on a flight vehicle. This dissertation describes the application of GPS attitude determination system in theory as well as experiments.With the help of phase observation equations, single differential, double differential observations and their error sources are analyzed at first. Then methods of attitude determination derived from baseline vectors are proposed, especially, a least squares attitude estimation procedure and a direct computation method for attitude are discussed in details, and error analysis of the estimated attitude parameters is performed. Last but not least, directed at the practical features of the task, a new ambiguity estimation searching based on space geometry conditions is analyzed. In order to improve reliability of attitude determination, a pyramid algorithm based on attitude constraints is presented.As far as experiment is concerned, an attitude system using GPS is composed by some low-cost CMC ALLSTAR receivers. Methods presented in this paper were tested on the static and dynamic condition. On the static real-time condition, an accuracy better than 0.1 degrees for heading for 4m long baseline has been achieved, and an accuracy better than 0.3 degrees for heading for 1m long baseline has been achieved. On the dynamic condition, the correction of algorithm has been demonstrated. Such a performance of multiple GPS sensors attitude systems demonstrate an alternative means to provide real-time, cost-effective, accurate and reliable attitude information for attitude surveys, and a key means to realize INS alignment on a moving platform.