Dynamic measurement of high-frequency deflections of the vertical based on the observation of INS/GNSS integration attitude error

Abstract

A novel method for dynamic measurement of deflections of the vertical (DOVs) by using the integration of inertial navigation system (INS) and global navigation satellite system (GNSS) has been proposed. Since the attitude errors of INS/GNSS integrated system are directly related to DOV, it is expected that DOV can be also estimated via the observation of INS/GNSS attitude errors. First, an attitude reference decoupled from DOV is constructed with the raw gyroscope data of the INS for INS/GNSS attitude error calculation. Then, DOV and various systematic errors including attitude reference error and inertial sensor errors are accurately modeled. The long-wavelength components of DOV are given by global gravity model, and the short-wavelength components are modeled as derivative second-order Gauss–Markov processes. Finally, DOV and systematic errors are simultaneously estimated by a Kalman smoother with the observation of INS/GNSS attitude error. A ship-borne survey campaign is conducted to validate the feasibility of the proposed method. Four sets of DOV data were obtained by two INS/GNSS integrated navigation systems along with two repeated survey lines. The experimental results show that the internal accuracy of the four sets of DOV data can reach better than 0.35″(1σ). When wavenumber correlation filter (WCF) algorithm is applied to the DOV data obtained by each system along the repeated lines, the DOV estimates from the two systems show good consistency, and the internal accuracy can be improved to about 0.2″(1σ).