Improved attitude algorithm for fiber-optic- gyro strapdown INS

Rotation vector algorithm regarded as a classical and conventional attitude algorithm is widely used in strapdown inertial navigation system. This kind of algorithm usually uses incremental angle in calculation processes. However, the output of fiber-optic gyro is angular rate. Integrating angular rate to get incremental angle leads calculation errors. In this paper, a set of improved attitude algorithms for fiber-optic-gyro strapdown INS using angular rate are developed and evaluated under classical coning motion. The error criterion for the improved algorithms and conventional ones is derived. Under the standard testing circumstance, i.e. classical coning motion, the accuracy of attitude calculation can be improved at least three orders of magnitude as compared with conventional one.