Postflight data-reduction techniques for hovered kinetic energy weapons

Abstract

One of the major concerns in attitude control of kinetic-energy-weapon vehicles proposed for exoatmospheric engagements is that error sources such as vehicle center-of-gravity variations and thrust misalignments of divert thrusters may induce excessive parasitic torques on the vehicle. These torques may result in significant attitude perturbations that are undesirable for target tracking, especially when using strapdown seekers. In an effort to identify and characterize these error sources in a quantitative way, it has been proposed to explicitly estimate them by using the data obtained from kinetic-energy-weapon hovered interceptor test flights. An estimation procedure based on extended Kalman filtering is developed for the postflight data reduction that includes the estimation of the center-of-gravity location and thrust misalignments. Some modifications to the basic extended Kalman filter algorithm are made to reduce the sensitivity of the estimator to uncertainties in divert thrust timing. The proposed estimation scheme is then used to process simulated flight data and actual test data. The data-reduction results are provided in this paper.