Near time-optimal feedback instantaneous impact point (IIP) guidance law for rocket

This paper proposes a feedback guidance law to move the instantaneous impact point (IIP) of a rocket to a desired location. Analytic expressions relating the time derivatives of an IIP with the external acceleration of the rocket are introduced. A near time-optimal feedback-form guidance law to determine the direction of the acceleration for guiding the IIP is developed using the derivative expressions. The effectiveness of the proposed guidance law, in comparison with the results of open-loop trajectory optimization, was demonstrated through IIP pointing case studies.