KHIT post-flight data reduction techniques based on Extended Kalman Filter

Abstract

One of the major concerns in attitude control of Kinetic-EnergyWeapon (KEW) vehicles proposed for exoatmospheric engagements is that some error sources such as vehicle center of gravity (CG) variations and thrust misalignments of divert thrusters may induce excessive parasitic torques. These errors may result in significant attitude perturbations which are undesirable for target tracking of strapdown seekers. In an effort to identify these error sources in a quantitative way, it has been proposed to explicitly estimate them by using the data obtained from KineticKill-Vehicle Hover Interceptor Test (KHIT) flights. An estimation procedure based on Extended Kalman Filtering (EKF) is developed for the post-flight data reduction that includes the estimation of CG location and thrust misalignments. Some modifications in EKF algorithms are made to reduce the sensitivity of the estimator to uncertainties in divert thrust timing. The proposed estimation scheme is then applied for processing simulated flight data and actual test data. The data reduction results are provided in this paper.