It is very important to apply rotation vector algorithm to the GFSINS that how to attain the relative angular displacement and meet its precision and updating frequency.

In the new algorithm, a time-variant forgetting factor is introduced to estimate the Mean Square Er-ror (MSE) and change the updating direction of adaptive filter coefficient vector.

An instance proved method of dynamic fussy symptom vector is efficient to solve the problems of symptom updating and unify of symptom value and unit.