A modified velocity updating algorithm for a strapdown INS

Abstract

Velocity updating typically involves integration of the transformed specific force and gravity Coriolis velocity increments. If the angular rate and specific force vectors maintain fixed directions relative to a frame, updating the velocity in that frame will be straightforward. In practice, the coning angular rate and sculling specific force vectors cause a calculation error in velocity updating on the navigation frame. Thus, the development of sculling compensation algorithms for the reduction of the sculling error is necessary. In this study, a new method for the propagation of vehicle velocity is proposed. This method utilizes an auxiliary frame that slews along with the angular rate and specific force vectors, which remain fixed in the auxiliary frame. This transforms and integrates the specific force vector in this auxiliary frame such that it is error-free. Additionally, the updated velocity can be obtained by translating the above results to the navigation frame, thereby avoiding the need for sculling correction. The validity of this proposed method under the influence of a typical slewing motion was established experimentally, suggesting that it provides an efficient and accurate velocity propagation method that can be employed in aerospace applications.