Parameterization-switching GNSS attitude determination considering the success rate of ambiguity resolution

Abstract

The two key elements of GNSS attitude determination are the correct integer ambiguity resolution (IAR) and the choice of appropriate method. The least-squares ambiguity decorrelation adjustment method is normally used to fix ambiguities using float estimates. However, it is difficult to get all ambiguities fixed in real time. Therefore, a method of partial ambiguity resolution which considers the success rate of IAR and makes full use of the ambiguity information at each epoch is proposed. The ambiguities after decorrelation can be divided into fixed ambiguities and unfixed ambiguities considering the fixing success rate. At the next epoch, the fixed ones are treated as constants, while the float estimates of the unfixed ones, along with the corresponding covariance matrix, are treated as prior information or pseudo-measurements. The parameters of the attitude determination problem can be baseline coordinates (BCs) or attitude angles (AAs). BC parameterization, without considering the baseline constraints, has the merit of resulting in a linear model; however, it involves parameter redundancy, which reduces the model strength. AA parameterization, although avoiding parameter redundancy, brings in nonlinearity and hence linearization errors in the least-squares solution. The linearization errors decrease as the number of fixed ambiguities increases. A switching-parameterization method is proposed; namely, at any epoch, as long as there are at least three fixed double-difference ambiguities, AA parameterization is adopted, otherwise BC is adopted. Even with AA, BC is firstly estimated and then transformed to attitude estimates at which the nonlinear measurement equations are linearized and solved. To verify the performance of the proposed method, a comparative study is implemented with BC and AA methods in the static experiment. The results show that the proposed method can fix ambiguity faster and have better stability and accuracy. In addition, the yaw angle is consistent with the actual running route of the vehicle in the kinematic experiment.

High-Accuracy Attitude Determination Using Single-Difference Observables Based on Multi-Antenna GNSS Receiver with a Common Clock

“…Complementary to inertial navigation systems (INSs), attitude determination based on global navigation satellite system (GNSS) short-baseline technology demonstrates its advantages of low cost and immunity to error accumulations [1]. With studies on the ambiguity resolution success rate [2,3] and the improvement in complex environments [4], the GNSS short-baseline attitude determination has attracted more attention in the autopilot and marine industries.…”

An Optimization Method of Ambiguity Function Based on Multi-Antenna Constrained and Application in Vehicle Attitude Determination

“…When Global Positioning System (GPS) went into service, some researchers proposed to use GPS multi-antenna (at least three receivers) to realize attitude determination. It is generally believed that carrier phase integer ambiguity resolution (AR) and the choice of the suitable method are the keys to high-precision attitude determination [2,3]. As long as the ambiguity is fixed correctly, the attitude can be determined based on the coordinates of the multi-antenna [4,5].…”

Effect of Nonlinear Baseline Length Constraint on Global Navigation Satellite System Compass: A Theoretical Analysis

“…ough single-epoch AR is the most challengeable [17], we should do AR sequentially to fully explore the temporally constant property of the ambiguities [18], as long as cycle slips are absent or repaired in real time [19]. In this work, we are concerned with yaw angle estimation with carrier-phase measurements whose ambiguities have already been fixed at previous epochs.…”