In-Flight Transfer Alignment/Calibration of a Strapdown INS That Employs Carouseled Instruments and IMU Indexing

An in-flight transfer alignment/calibration technique has been developed for the new Delco Electronics low cost inertial navigation system (LCINS). In-flight transfer alignment/calibration makes accurate guidance possible for a vehicle launched from a carrier aircraft without performing a pre-flight field alignment/calibration. The carrier aircraft possesses a master navigator which provides the reference information for LCINS operating as a slave navigator during the alignment/calibration process. Delco´s alignment/calibration implementation employs a 25-state Kalman estimator that uses carousel-induced modulation and IMU indexing to optimally estimate the IMU attitude and calibrate the unknown instrument coefficients.