The Research On Multi-antenna GPS Attitude Determination Algorithm

Attitude determination is an important branch of GPS measurement.Because GPS has so many advantages,such as high precision,all weather,low cost,it has been widely concerned in the field of attitude determination and other applications.GPS phase observation can achieve high-precision positioning and attitude results.With the lack of enough number of observed satellites,the success rate of ambiguity solution is very low,as well as the ineffective attitude solution.When the baseline length is fixed,the baseline length will act as a high-precision observation to help the ambiguity solution.For the short baseline constraint,in this paper,we proposed an ambiguity search method with nonlinear constraints of baseline length,which greatly improves the success rate of ambiguity solution and the measurement accuracy of the baseline.In terms of the attitude determination,TRIAD and QUEST are mainly studied,and the relationship between the two algorithms in solving the dual-baseline attitude is analyzed.The main research content of this paper is multi-antenna GPS attitude determination algorithm.The solution process is divided into two steps: Firstly,completing the ambiguity solution;secondly,realizing attitude determination.For the part of the ambiguity solution methods,we study the ambiguity solution method under the constraint of ultra-short baseline.Sometimes the baseline length is too short,the solution using the linear model established by the baseline length directly is ineffective.Considering the use of the baseline length nonlinear model to search for ambiguity,and it improves the success rate of the ambiguity solution.For the part of the attitude determination algorithms,TRIAD and QUEST are studied in this paper.The two algorithms are compared and analyzed,the relationship between the two algorithms and the equivalence between the two algorithms is obtained.The ambiguity searching method under the ultra-short baseline constraint proposed in this paper is verified by the measured data.Compared with the LAMBDA algorithm without baseline constraint and the LAMBDA algorithm under the baseline length linear constraint,the success rate of ambiguity is increased by 30% to 40%.and the accuracy of corresponding baseline is also improved accordingly.As to dual-baseline attitude determination with one baseline of low accuracy,this paper verifies by the measured data: 1)TRIAD algorithm depends on the main vector accuracy.The improved algorithm solved dependency problem,and improved the measurement accuracy;2)When the TRIAD and QUEST algorithm have the same effect in attitude determination,the two baselines in the precision to meet the special conditions.When baselines are all solved with high accuracy,the accuracy of attitude determination is generally effective.Actually,not all baseline accuracy is very high in GPS attitude measurement.This paper provides a theoretical basis for the efficient dual-baseline attitude determination when one of the baselines accuracy is not high.