Two-Stage Impact Time Control Guidance with Limited Field of View Based on Periodic Delayed Feedback

This article proposes a two-stage guidance law for impact time control under field-of-view (FOV) constraint. In the first stage, a desired look angle profile is designed to strictly satisfy the impact time constraint, with additional modifications to address both the FOV constraint and potential singularities. To ensure precise profile tracking within a prescribed time, a look angle tracking guidance law based on periodic delayed feedback is subsequently developed. In the second stage, a range-varying proportional navigation guidance is employed, ensuring the convergence of both the look angle and acceleration command to zero. To further enhance robustness, a disturbance-observer-based composite guidance law is introduced. A key feature of the proposed guidance law is its operation without time-to-go estimation, numerical iterations, or linearization, while achieving a broader impact time region compared to existing methods. Finally, extensive numerical simulations demonstrate the effectiveness, robustness, and superiority of the proposed guidance law.