A Midcourse Estimation and Guidance Law for Space Based Interceptors

The proposed guidance approach places emphasis on estimation of the current target state, via least mean squares and Kalman Filtering. This forms the basis for projecting ahead the targets future position. One is then able to solve the Intercept Point Prediction problem and directly aim the interceptor towards the Intercept Point. This results in a collision course guidance scheme. For mechanization of this scheme a hierarchical approach, where in the "outer loop" one first addresses the Intercept Point Prediction problem, followed by classical Proportional Navigation for small corrections around the Intercept Point, is proposed. Methods for target state estimation are provided and explicit solution for the Intercept Point Prediction problem is given. Subsequently, a guidance algorithm based on correcting for perceived Intercept Point movements is presented. Next, a correction term for the "gravity drop" is provided. The contributions of this paper are the Intercept Point correction methods which compensate for the perceived drift of the Intercept Point during the engagement and for the gravity drop.