Tightly coupled SINS/GNSS integration based on simplified SSKF

The spherical simplex Kalman filter (SSKF) used in tightly coupled SINS/GNSS integration is simplified, namely simplified SSKF, due to the linear state equation but the nonlinear observation equation. Using state prediction of common Kalman filter (FK) and observation prediction of SSKF, the generating and updating of each sigma point during state prediction is omitted in simplified SSKF, which can shorten filtering time with less accuracy loss. Through mathematical simulations, simplified SSKF is proved to be more efficient than common SSKF. Besides, simplified SSKF has almost the same position (velocity) accuracy as common SSKF.