Approach for altitude damping in integrated ship navigation system based on robust UKF filtering

The altitude damping is an important problem in ship navigation system which directly affects the combat efficiency of warships. In order to solve the problem of vertical channel divergence in pure inertial navigation system, an INS/GPS third-order vertical channel damping loop was designed. Meanwhile, a filtering algorithm was adopted to damp the main error source to prevent it from causing altitude error. Based on the concept of Euler platform error angles, a nonlinear SINS error model with arbitrary initial misalignment angles was proposed. By combining H-infinite theory with the unscented transformation, a robust UKF algorithm was also deduced. Finally, an altitude damping simulation test was conducted. The results show that the altitude damping approach in integrated ship navigation system based on the robust UKF filtering can efficiently damp the altitude calculation, and the altitude damping accuracy is roughly equivalent to the accuracy of external measurement information.