Performance improvement of GPS single frequency, single epoch attitude determination with poor satellite visibility

Abstract

Similar to global positioning system (GPS) positioning in urban canyons, a fast and successful attitude determination with limited satellite visibility is very significant. For land vehicles, the possible attitude candidates can be treated as a spherical zone with the center at the reference antenna and the baseline as the radius. This provides an important constraint, which can be exploited to improve the reliability of GPS single frequency and single epoch attitude determination in the case of poor satellite reception. First, we fully integrate the spherical zone constraint into the estimation procedure of ambiguity resolution, but not in the validation procedure. Combining both the coordinate domain search and the ambiguity domain search, allows development of a global minimizer of the fixed ambiguity objective function. This scheme also improves the precision of the float ambiguity solution, thus avoiding the problem of search halting. The performance of the new ambiguity resolution method was analyzed by means of several experimental tests, using simulated as well as actual GPS data in urban environments. The experimental results showed that this new, proposed method can utilize a priori spherical zone knowledge to improve the reliability of ambiguity resolution in difficult environments.