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

Abstract

A global navigation satellite system (GNSS) receiver with multi-antenna using clock synchronization technology is a powerful piece of equipment for precise attitude determination and reducing costs. The single-difference (SD) can eliminate both the satellites and receiver clock errors with the common clock between antennas, which benefits the GNSS short-baseline attitude determination due to its lower noise, higher redundancy and stronger function model strength. However, the existence of uncalibrated phase delay (UPD) makes it difficult to obtain fixed SD attitude solutions. Therefore, the key problem for the fixed SD attitude solutions is to separate the SD UPD and fix the SD ambiguities into integers between antennas. This article introduces the one-step ambiguity substitution approach to separate the SD UPD, through which we merge the SD UPD parameter with the SD ambiguity of the reference satellite ambiguity as the new SD UPD parameter. Reconstructing the other SD ambiguities, the rank deficiency can be remedied by nature, and the new SD ambiguities can have a natural integer feature. Finally, the fixed SD baseline and attitude solutions are obtained by combining the ambiguity substitution approach with integer ambiguity resolution (IAR). To verify the effect of the ambiguity substitution approach and the advantages of the SD observables with a common clock in practical applications, we conducted static, kinematic, and vehicle experiments. In static experiments, the root mean squared errors (RMSEs) of the yaw and pitch angles obtained by the SD observables with a common clock were improved by approximately 80% and 93%, respectively, compared to double-difference (DD) observables with a common clock in multi-day attitude solutions. The kinematic results show that the dispersion of the SD-Fix in the pitch angle is two times less that of the DD-Fix, and the standard deviations (STDs) of the pitch angle for SD-Fix can reach 0.02°. Based on the feasibility, five bridges with low pitch angles in the vehicle experiment environment, which the DD observables cannot detect, were detected by the SD observables with a common clock. The attitude angles obtained by the SD observables were also consistent with the fiber optic gyroscope (FOG) inertial navigation system (INS). This research on the SD observables with a common clock provides higher accuracy.

Sea Surface Height Measurements Based on Multi-Antenna GNSS Buoys

“…From the results of the attitude solution, the normal high attitude correction for the instantaneous sea surface height on our designed buoy was within 1 cm (Figure 12), while a small amount of correction exceeding 1 cm existed, but these higher corrections were not based on the attitude angle corrected from the normal solution, but were due to the unfixed ambiguity in the dynamic baseline solution process leading to the error in the attitude angle solution [35,36]. (3) After correcting the tidal data of the GNSS buoy using the attitude angle measured by the multi-antenna GNSS, the tidal measurement accuracy was only improved by 0.3 mm compared to the pre-correction values, and similar problems have been…”

“…From the results of the attitude solution, the normal high attitude correction for the instantaneous sea surface height on our designed buoy was within 1 cm (Figure 12), while a small amount of correction exceeding 1 cm existed, but these higher corrections were not based on the attitude angle corrected from the normal solution, but were due to the unfixed ambiguity in the dynamic baseline solution process leading to the error in the attitude angle solution [35,36]. (3) After correcting the tidal data of the GNSS buoy using the attitude angle measured by the multi-antenna GNSS, the tidal measurement accuracy was only improved by 0.3 mm compared to the pre-correction values, and similar problems have been encountered by scholars in previous studies [37], which occurred for two reasons: first, because the wobble angle of the buoy itself is not large (−10 • ~10 • ), and the second is that the distance of the main antenna of the GNSS buoy from the center of the buoy was very short (0.61 m), which, under the combined influence of these two factors, leads to a small amount of attitude correction for the GNSS buoy, which was not prominent in the tidal extraction process.…”

Multi-dimensional particle filter-based estimation of phase line biases for single-differenced ambiguity resolution in GNSS-based attitude determination

“…Previous works have investigated the advantages of the SD model over the DD model with a common-clock receiver. It is found that with respect to the DD model, the achievable baseline accuracy of the SD model in the vertical could be improved to the same level as the horizontal, and the accuracy of pitch and roll could be improved to the same level as for yaw [8,[13][14][15][16][17].…”

“…The existence of these phase LBs therefore prevents the SD integer ambiguity resolution (AR). One way to tackle this problem is parameter reorganization, which is simple to implement but only DD ambiguities are resolved [8,14]. An alternative approach is first calculating and filtering the phase LBs over time and then correcting them with the SD model, in which the DD and SD models are utilized simultaneously [18][19][20].…”

An Overview of a Special Issue on Upcoming Positioning, Navigation, and Timing: GPS, GLONASS, Galileo and BeiDou

“…Ref. [13] proposed a single-difference (SD) approach to retain the advantages of SD observables and a one-step ambiguity substitution technique to separate ambiguities from SD uncalibrated phase delay. The proposed method was validated in both static and kinematic modes, and the results were consistent with the reference attitude data.…”