Research Of Orientation Determination Technology Based On GPS Single Epoch Calculation

Global Positioning System can provide precise, continuous three-dimensional position and velocity information to global users with the appropriate receivers in all-weather, and has a good anti-interference and confidentiality. Attitude determination using GPS is an interest area of applications of GPS, and be widely applied in aero and navigation.This paper focused on the theory of orientation determination based on GPS. Specifically as following:1. Generally described the basic principles of GPS systematically, including the components of GPS system, positioning with the TOF principle of the pseudo-range, the theory of carrier phase attitude determination measurement, navigation data and information, discussed the error source generated by using GPS measurement, the accuracy and so on.2. Deeply discussed the definition of attitude angle with GPS measurement, the relationship between baseline attitude and vehicle's geometry. Derive the conversion between coordinate systems and the calculation method of three-dimensional attitude angle.3. Studied the internal and abroad status of using GPS carrier phase technology to calculate attitude angle, made a brief introduction of the general process and classical methods for determine the integer ambiguity. Also propose a double difference analysis search method which can solve the integer ambiguity problem. By using the carrier phase double difference observations, the composition relative vector of the two satellites'position and the characteristic that the length of the baseline can be accurately measured, the calculation for the double difference integer ambiguity possible values could be done. The analytical solution for the satellite carrier phase double difference equations between different compositions can realize the orientation function.4. According to the proposed double-difference ambiguity resolution search method, the GPS satellites data acquisition program and the satellite position solution software interface was written in the VB environment. Using GPS satellites carrier phase double-difference observations and the analysis method to search the double-difference ambiguity value, and achieve the determination for the true attitude angle of the baseline in Matlab program. Works have been done for making the criteria of excluding the double difference ambiguity candidate results.5. Flow the proposed algorithm, single-baseline experiment with GPS attitude measurement was carried out. Experiment's results show that in the case whose length of the baseline is 2 meters, the Yaw measurement accuracy is about 0.15°, with using single-epoch data. Aim at the experiment's results and the performance of the algorithm, the accuracy, the computation algorithms, and initialization time, were analyzed. Its availability and feasibility has been verified.