Strapdown INS initial alignment in inertial frame using H∞ filter

Initial alignment is the key procedure in the strapdown inertial navigation system (INS), which directly relates to the working precision of strapdown INS. But the tradition alignment method can't finish alignment under the dynamic disturbance condition. In this paper, a novel alignment method using H∞ filter was investigated to solve this problem. In the coarse alignment procedure, the invariance property of gravity in the inertial frame was used to deal with the disturbances. In the fine alignment procedure, strapdown INS alignment error model under the dynamic condition was established. Moreover, because of the uncertainty observation noise in the velocity measurements, the H∞ robust filter was designed to estimate the misalignment angles accurately. Finally, simulation results demonstrated that the proposed method can depress the random disturbances more effectively than the traditional alignment method. © 2014 Binary Information Press.