Predictor Observers for Proportional Navigation Systems Subjected to Seeker Delay

We propose predictor observers as viable tools to compensate for pure time delays in the seeker subsystem of missile guidance systems employing proportional navigation guidance (PNG). With the intention of use in terminal guidance in which the missile is already on a near-collision course with a target, we demonstrate that a classical predictor observer for linear time-delay systems is input-to-state stable (ISS) with respect to bounded target maneuver and measurement disturbances. We then show how the classical predictor observer can be implemented as a Kalman filter for the delayed state augmented with a predictor. Finally, we illustrate the practicality of the approach in missile guidance system design through two examples that exhibit seeker delay and random target maneuvers. For both examples, numerical simulations show that predictor observer guidance laws are able to substantially reduce miss distance versus baseline PNG laws that have no delay compensation, inviting further studies of the approach for designing real missile guidance systems in practice.