Observability analysis of inertial navigation errors from optical flow subspace constraint

Rapid detection of index for encoder in rotary inertial navigation system

This paper presents an approach to detect the index of incremental photoelectric encoder with shorter time for rotary inertial navigation system. The order of index detection and coarse alignment is exchanged in this approach and information from coarse alignment is used to calculate the direction of index. Then two cases of azimuth axis and four cases of horizontal axes are analyzed and corresponding solutions are designed. The paper examines the solutions through two experiments in a tri-axis rotary inertial navigation system, and the results demonstrate that the system can capture index pulse in the application of the presupposes schemes with shorter time.