Application of SUKF filtering in initial alignment of large misalignment angle of SINS

The system error equation of Strapdown Inertial Navigation System(SINS) for large misalignment angle is nonlinear,thus it is urgent to solve the problem of initial alignment in SINS when the error equation is nonlinear.An approach of Scaled-Unscented Kalman Filter(SUKF) based on Scaled-Unscented Transformation(SUT) is presented.SUKF is then applied in the nonlinear alignment model based on the error of quaternion.The initial alignment of large misalignment angles is simulated by using Extended Kalman Filter(EKF) and SUKF respectively.The results indicate that SUKF is better than EKF in convergence speed and estimation precision.