Abstract
For Global Navigation Satellite System (GNSS) single frequency, single epoch attitude determination, this paper proposes a new reliable method with baseline vector constraint. First, prior knowledge of baseline length, heading, and pitch obtained from other navigation equipment or sensors are used to reconstruct objective function rigorously. Then, searching strategy is improved. It substitutes gradually Enlarged ellipsoidal search space for non-ellipsoidal search space to ensure correct ambiguity candidates are within it and make the searching process directly be carried out by least squares ambiguity decorrelation algorithm (LAMBDA) method. For all vector candidates, some ones are further eliminated by derived approximate inequality, which accelerates the searching process. Experimental results show that compared to traditional method with only baseline length constraint, this new method can utilize a priori baseline three-dimensional knowledge to fix ambiguity reliably and achieve a high success rate. Experimental tests also verify it is not very sensitive to baseline vector error and can perform robustly when angular error is not great.
Highlights
Global Navigation Satellite System (GNSS) double-differenced carrier phase observables can be used for high precision attitude determination, and the key is integer ambiguity resolution
For single epoch attitude determination, Chansik Park and Teunissen propose their own nonlinear constrained integer least square method and relevant searching strategy [10,11]. Both methods integrate nonlinear constraints into ambiguity objective function, the former is based on least squares ambiguity decorrelation algorithm (LAMBDA) ellipsoidal search space, and the latter is based on a more rigorous but complex non-ellipsoidal search space
The inverse of variance of each item in objective function is set as a weighted value
Summary
GNSS double-differenced carrier phase observables can be used for high precision attitude determination, and the key is integer ambiguity resolution. For single epoch attitude determination, Chansik Park and Teunissen propose their own nonlinear constrained integer least square method and relevant searching strategy [10,11] Both methods integrate nonlinear constraints into ambiguity objective function, the former is based on LAMBDA ellipsoidal search space, and the latter is based on a more rigorous but complex non-ellipsoidal search space. Other research on GNSS attitude determination methods without combination mainly focuses on misaligned baselines [14], instantaneous ambiguity resolution and attitude determination [15], and medium-length baselines and multi-frequency single epoch attitude determination [16,17] These methods do not accommodate whole prior baseline vector information into constraint and only take baseline length into consideration. L can be measured very precisely, and δl is very small. θ and β are measured by other airborne navigation systems and sensors with rough precision and bigger variance
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