Practical time-to-go estimation methods for optimal guidance

This paper addresses the problem of computing practical and accurate time-to-go estimates, which is an important issue in implementing various optimal guidance laws developed for missiles of time-varying velocity. A recursive time-tó-go computation method which updates the time-to-go in a non-iterative way is presented. The recursive method includes an error compensation feature which explicitly computes the time-to-go error produced by nonzero initial heading errors. The proposed method is simple and straightforward to implement for any missile velocity profiles. Various numerical examples show that the proposed method works effectively for optimal guidance laws as weil as proportional navigation and augmented proportional navigation laws when implemented using time-to-go.