Velocity propagation with a time-varying slew rate vector for strapdown INS

Abstract The traditional velocity integration algorithms in a strapdown inertial navigation system are to approximate the rotational vector which related to the transformation matrix and then integrate the transformed specific force vector over the velocity update interval. In order to eliminate approximate integration error existed in the traditional algorithms, a new velocity integration algorithm with a time-varying slew rate vector is developed in this paper. An additional frame, the slewing frame which slews along with the angular rate and specific force vectors, is constructed to design and form the optimized algorithms of velocity. The relative position among the angular rate vector, the specific force vector and the slewing frame is fixed. So it is convenient to get a precise rotation vector. In addition, a more general testing circumstance called the time-varying slewing motion developed in this paper for evaluation of the velocity integration algorithms. It is more complex and severer than the classic sculling motion. Simulation test results under the classic sculling motion and the time-varying slewing motion demonstrate that the proposed velocity integration algorithm has better performance than the traditional one.