An Alternative Formulation for High-Order Intercept Guidance Laws

This paper presents an alternative formulation for linear intercept guidance laws. These guidance laws are in terms of zero effort miss (ZEM) vector premultiplied by a gain matrix. The ZEM consists of state vectors of the problem, each of which multiplied by a time-varying gain. If the time derivatives of the interceptor acceleration are chosen as the state variables of the interceptor control system, these derivatives can be replaced by the time derivatives of the line-of-sight (LOS) rate. The interceptor acceleration is given by the acceleration relations of polar coordinates for relative motion. Therefore, the time derivatives of the acceleration are already available by taking the time derivatives of the relation. For the linearized intercept problem, the closing velocity is assumed to be constant, and the formulation is simplified. The linearized ZEM is obtained as a summation of the LOS derivatives, each of which multiplied by a time-varying gain. These gains are functions of time-to-go and autopilot parameters (e.g., time constants and damping ratio) multiplied by the closing velocity.

Keywords:

Linear Optimal Guidance - Intercept Guidance , Zero Effort Miss.