Design of a near optimal midcourse guidance law for exoatmospheric interceptor

A near optimal midcourse guidance strategy with fixed-interval propulsive maneuvers for exoatmospheric interceptor is proposed. Firstly, a new analytic expression of relative motion is derived, because the difference of gravity for interceptor and ballistic missile is taken into account, so the expression had good fidelity than the case where gravitational accelerations acting upon both vehicles are equal. The expression and Pontryagin's minimum principle are combined to obtain a closed-loop form acceleration command. In order to improve the performance of the guidance law, a residual acceleration is introduced. Simulation results show that presented guidance law is effective.