Baseline-constrained single-epoch GNSS attitude determination using a priori attitude information

Instantaneous Global Navigation Satellite System (GNSS) attitude determination method which achieves real-time attitude determination using GNSS signal has been extensively studied, particularly the one using a priori attitude information replacing the code measurements to enhance the successful rate for ambiguity resolution. However, there exists a key limitation that this method relies on considerable Monte Carlo sampling particles to construct the pdf of ambiguities, resulting in significant computational burdens. To address this limitation, this paper provides a rapid single-epoch GNSS attitude determination method based on a priori attitude information. It utilizes a second-order Taylor expansion to analytically estimate the covariance of the baseline conditioned on a priori attitude information. This is followed by deriving the float solution and covariance of ambiguities, which are then processed using the standard LAMBDA method for integer ambiguity resolution. Experimental results demonstrate that our method is both efficient and accurate, significantly reducing computational costs compared to previous methods, thereby enhancing its applicability for GNSS-based attitude determination.