Comparison of inertial navigation system error models in application to IMU transfer alignment

Abstract

,This paper compares IMU transfer alignment results from using different INS system error model forms for a local level wander azimuth system. Actual recorded test data is processed by Kalman filter implementations of three INS error dynamic models. These three INS error model forms are obtained by using velocity error representations referred to as either computer frame or perturbation forms. For the computer frame form, two variations of that form are obtained from either of the assumptions - the local vertical axis tilt error, $z, is zero, or the navigation frame vertical axis misalignment, 66z, is zero. The perturbation form assumes the local vertical axis tilt error, 2 = 0 , and perturbation model results are similar for estimating the body referenced misalignment between the IMU and the aircraft's reference navigation system; and 3) the computer frame model, with ddt = 0 , produces results that more accurately reflect navigation system errors during aircraft maneuvers.