Adaptation of a strapdown formulation for processing inertial platform data

An estimator propagation formulation, which utilizes dynamic data (attitude and sensed acceleration information) from a gimballed inertia! platform, has been developed to aid in the Shuttle postflight trajectory reconstruction process and aerodynamic coefficient determination studies. Unlike classical inertial algorithms, this formulation yields a six degree-of-freedom fully coupled state and attitude estimate. Furthermore, this inertial version is shown to be independent of initial unknown platform misalignments. Results obtained using actual Inertial Measurement Unit (IMU) Data and Aeodynamic Coefficient Identification Package (ACIP) strapdown data from Shuttle flights are presented.