Concepts for payload to launch vehicle transfer alignment during boost and freefall

Summary form only given. The authors present an application of attitude velocity match algorithms useful for attitude keeping of an interceptor navigation and target acquisition system. It operates by comparing computed attitude and velocity from a high-quality launch vehicle inertial measurement unit (IMU) with the attitude and velocity computed using a strapdown payload IMU. The residual attitude and velocity differences measured during launcher boost, divert manuevers to shape the launcher trajectory, and/or freefall are a direct indication of mechanical misalignments, interceptor initial attitude error, and IMU uncertainties, and are used in a Kalman filter to estimate those quantities. A detailed analysis of a transfer alignment and instrument calibration filter for a payload IMU has been carried out. Also obtained was a complete derivation of the attitude/velocity match algorithms. A filter sizing study was carried out, and the sensitivity of the suboptimal filter to the unmodeled error states and the incorrectly modeled measurement noise and errors are evaluated