Modern Accuracy of Instantaneous Attitude Determination Using Multi-Antenna Multi-GNSS

The research focuses on the analysis of the accuracy of attitude determination using satellite measurements from a multi-antenna Global Navigation Satellite System (GNSS). Carrier phase satellite measurements are characterized by the presence of integer ambiguities. Conventional methods based on carrier phase measurement decorrelation techniques are used in this work to resolve integer ambiguities. We propose a method of accuracy estimation of attitude determination using multi-antenna multi-GNSS (GPS, GLONASS, Galileo, BeiDou) in a special experiment to obtain the reference attitude with low-cost inertial measurement unit (IMU). This method addresses the common issue of a vicious cycle in many studies, where the solution to be verified is also used to derive the reference solution, thereby removing bias and ensuring independent validation. Experimental data from 5 GNSS antennas mounted on a rotatable board with inter-antenna distances of approximately 1 m are processed. The obtained reference attitude achieves an accuracy 2 to 3 times better than that of typical modern multi-antenna GNSS systems. This enhanced accuracy enables a detailed study of attitude errors, decomposable into low-frequency and high-frequency stochastic components. We further conduct a cross-generation hardware comparison of attitude determination accuracy and analyze its dependence on the number of GNSS constellations used. Solutions from newer generation hardware demonstrate approximately 20% higher accuracy compared to older hardware. The most accurate multi-GNSS constellation combinations are identified: Among 2-system setups, Galileo and BeiDou provide the highest accuracy. In 3-system configurations, adding GLONASS to Galileo and BeiDou provides the best yaw accuracy, while including GPS yields the best pitch accuracy.