Effects of time-to-go errors on performance of optimal guidance laws

This paper describes the sensitivity analysis concerning time-to-go estimation error for the class of optimal impact angle control guidance laws under a stationary or a slowly moving target. First, in this paper, the closed-form solutions of those guidance laws for a lag-free system are determined. Then, we derive the explicit expressions of the terminal errors (i.e., miss distance and impact angle error) in the presence of a constant positive time-to-go estimation error. Based on these results, the guidance parameters that can help reduce the sensitivity to time-to-go estimation error are identified. Additionally, the terminal performance of the presented optimal impact angle guidance laws is evaluated from the standpoint of robustness against the time-to-go estimation errors. Numbers of linear homing simulations are also performed to confirm the analysis results.