Abstract
The global navigation satellite system (GNSS)-based multi-antenna attitude determination method has the advantages of a simple algorithm and no error accumulation with time in long endurance operation. However, it is sometimes difficult to simultaneous obtain the fixed solutions of all antennas in vehicle attitude determination. If float or incorrect fixed solutions are used, precision and reliability of attitude cannot be guaranteed. Given this fact, a baseline-constrained ambiguity function method (BCAFM) based on a self-built four GNSS antennas hardware platform is proposed. The coordinates obtained by BCAFM can replace the unreliable real-time kinematic (RTK) float or incorrect fixed solutions, so as to assist the direct method for attitude determination. In the proposed BCAFM, the baseline constraint is applied to improve search efficiency (searching time), and the ambiguity function value (AFV) formula is optimized to enhance the discrimination of true peak. The correctness of the proposed method is verified by vehicle attitude determination results and baseline length difference. Experimental results demonstrate that the function values of error peaks are reduced, and the only true peak can be identified accurately. The valid epoch proportion increases by 14.95% after true peak coordinates are used to replace the GNSS-RTK float or incorrect fixed solutions. The precision of the three attitude angles is 0.54°, 1.46°, and 1.15°, respectively. Meanwhile, the RMS of baseline length difference is 3.8 mm.
Highlights
Once the ambiguities of the rover station cannot be fixed, the search scope will be large, and it is not easy to determine the specific range; the other is that the coordinate accuracy obtained by ambiguity function method (AFM) depends on search steps
We realize a multi global navigation satellite system (GNSS) antenna vehicle positioning and attitude determination algorithm based on a self-built four antenna platform
The experimental results show that the single epoch search time of baseline-constrained ambiguity function method (BCAFM) is less than 0.5 s
Summary
As long as the ambiguity is fixed correctly, the attitude can be determined based on the coordinates of the multi-antenna [4,5]. AFM is a search method based on the coordinate domain and does not explicitly calculate the ambiguity but directly uses the integer characteristics of ambiguity [38]. There are mainly two reasons for low efficiency: one is that the search scope depends on the positioning accuracy of the rover station. Once the ambiguities of the rover station cannot be fixed (only float or SPP solutions), the search scope will be large, and it is not easy to determine the specific range; the other is that the coordinate accuracy obtained by AFM depends on search steps.
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