GPS Attitude Measurement And Ambiguity Study

GPS carrier attitude measurement system has wide application prospect that it has the characteristics of low cost, measurement error does not accumulate with time,working environment requirement is low, can all-weather vectors to any place on the earth were measured by longitude and latitude limits, the system installing and operating is simple and using is easy. At present, single epoch attitude measurement technology is always used in the practical application of GPS attitude measurement to get the attitude data real-time or faster. There is a wide range of applications of single epoch attitude measurement,because it involves a simple model, it’s solution is.However,in the existing technical conditions, measurement accuracy is low because of the less the data. In this paper, we try to introduce the Ratio accumulation method to the solution of GPS attitude measurement.. A core problem of GPS attitude measurement is the degree of integer ambiguity solution. The ratio value accumulation method can use a degree of ambiguity relationship between the epoch to help determine the integer ambiguity,increase the accuracy of the determined integer ambiguity reliability, and ultimately improve the attitude determination accuracy. This paper is divided into 4 parts:GPS attitude measurement is based on the carrier phase measurement technology,and the attitude of the carrier is actually the relationship between the geographic coordinate system and the vector coordinate system.. In this paper, the author introduced the space part, the ground part and the user part of GPS, and also introduced the GPS signal structure and the content of the composition is carrier phase measurement equation and carrier phase single differential and double difference observation equations, the conversion relationship between the various coordinate in GPS attitude measurement is discussed else.In the process of using GPS carrier phase measurement of aircraft attitude, integer ambiguity can be calculated, solving fast or not is the key factor for GPS real-time attitude determination technology. In this paper, the author introduced the ambiguity resolution process, a detailed analysis of LAMBDA algorithm and the process of reducing the search process, and the LAMBDA algorithm of MLAMBDA is analyzed,the comparison between two algorithms.Aiming at the deficiency of single epoch attitude measurement, the ratio accumulation method for GPS carrier attitude measurement is proposed in this paper.First, Each epoch ambiguity and corresponding ratio values is solved by MLAMBDA algorithm and the single epoch fuzzy degree calculation method, then the same fuzzy combination of ratio values are accumulated, select cumulative ratio value and the maximum fuzzy combination to determine the fuzzy degree, and then fuzzy degree to calculate out the baseline, finally get the attitude information of the vehicle.A simulation of GPS attitude measurement is made by using MATLAB2014 a and the ratio value accumulation method. The attitude data of solved by data of all the epoch was used as the reference to compare with the single epoch solution results and use the ratio value accumulation method different epochs of the calculation results and the calculation results of different epochs which using the ratio value accumulation. The results show that the Ratio accumulation method can quickly obtain attitude data for attitude measurement and improve the accuracy of result of Single epoch attitude measurement.