Robust Discrete-Time Proportional-Derivative Navigation Guidance

A discrete-time, proportional-derivative navigation guidance (PDNG) law for the terminal phase of an engagement with emphasis on the effect of a digital implementation, is proposed. A missile-target engagement on a two-dimensional plane is formulated by assuming that lateral and longitudinal planes are decoupled by means of roll control. The missile-target system is simulated and the acceleration of a slightly damped maneuvering target is determined. The pattern of the PDNG control signal is found to be slightly different from that of OGL because the former adopts high values at the beginning of the homing phase while avoiding saturation. As optimal guidance law (OGL) relies on the assumption of unitary gain missile dynamics, the performance of OGL becomes sensitive to response times obtained with realistic flight-control dynamics.