Optimal Guidance with Constraints on Impact Angle and Terminal Acceleration

Numbers of impact angle guidance laws have been studied in order to satisfy the flight path angle constraint on each waypoint that unmanned aerial vehicles for reconnaissance should pass by, or to increase the warhead effect for anti-ship or anti-tank missiles. These guidance laws converge to a finite value as the missile approaches to the target so that sometimes maneuver acceleration can easily be saturated in real situation. The saturation of maneuver acceleration in terminal phase may cause large miss distance and impact angle error. In this paper, an optimal guidance law with the capacity of adjusting terminal maneuver acceleration is studied to control impact angle as well as miss distance. Constant speed missiles with the 1 order system lag are assumed for deriving closed-form state feedback guidance law. Since the proposed guidance law is able to nullify the maneuver acceleration at impact instant, not only it is robust to disturbances or uncertainties in terminal phase, but also the performances of terminal miss due to command saturation to prevent structural failure or flight instability is improved.