Improving missile guidance performance by in-flight two-step nonlinear estimation of radome aberration

A new technique is presented for compensating radome-induced line-of-sight (LOS) aberrations in active radar-guided homing missiles based on a novel nonlinear estimation algorithm. Decoupling of radome errors from the nominal missile state is achieved by implementing a two-step estimator that utilizes nonlinear measurements of the radome-corrupted azimuth and elevation LOS angles. Elaborate aerodynamic and kinematic models are used to establish a realistic interception setup, which constitutes a basis for a thorough performance evaluation and comparison of the new algorithm to a traditional extended Kalman filter. It is shown that the new approach requires neither specialized observability maneuver nor dithering to estimate the radome slopes. An unbiased, efficient estimate of radar slopes yielded by the new method permits considerable reduction of miss distance.