A Dynamic Initialization Method for LEO/INS Integrated Positioning

In the context of Global Navigation Satellite System (GNSS) denial environments, positioning can be achieved using low Earth orbit (LEO) satellite signals of opportunity (SOPs). When the instantaneous visibility of LEO satellites is insufficient, independent dynamic positioning cannot be realized, necessitating the combination with inertial navigation systems (INSs) for dynamic positioning. However, in current research, LEO/INS integrated positioning either requires the initialization of states using GNSS/INS or demands a prolonged stationary period to utilize SOP for providing initial states. Both of these scenarios severely limit practical applications. Addressing this issue, this article proposes an initialization method based on dynamic multiepoch (D-ME), enabling independent dynamic initialization of Iridium satellites and INS with a very minor loss of positioning accuracy. Due to the low orbital altitude of LEO satellites, arbitrary selection of initial iteration values for position is not feasible. To ensure the strong convergence of the initialization model, an algorithm is proposed based on Iridium signal pseudorange differences and Doppler differences (PDs-DDs) for determining initial position iteration values. Vehicular experiments were conducted using actual Iridium signals, and the results indicate that, compared with GNSS initialization and the 15-min static initialization, the 15-min dynamic initialization based on the proposed method can achieve comparable positioning performance after filter convergence.