An improved method for gravity disturbances compensation in INS/GPS integrated navigation

Though the gravity-induced velocity and position errors can be easily dumped in GPS/INS integrated navigation, the attitude estimation errors are more affected by the gravity disturbance errors. In this paper, an improved gravity disturbance compensation method is performed to reduce the gravity-induced attitude measurement error in inertial navigation system (INS) and global positioning system (GPS) integrated navigation. Specifically, the long and medium wavelength components of the gravity disturbance are compensated by using the EGM2008 global gravity model, and then a derivative second-order Gauss-Markov process is adopted as a statistical model of the short-wavelength components, which are estimated and removed online by a Kalman filter. Simulations results show that the proposed statistical model can decouple the short-wavelength components of gravity disturbances from the attitude errors. Therefore, the attitude errors are reduced effectively when the improved compensation method is applied.