Field-of-View Constrained Optimal Guidance Law for Impact-Time and Angle Control

This study proposes a twofold approach for designing an impact-time and angle control guidance law under a field-of-view (FOV) constraint. First, an impact-angle control guidance law is derived by assuming the line-of-sight angle profile to be a second-degree polynomial function of the range-to-go. This reduces the guidance problem to determining the polynomial coefficients that enforce the boundary conditions required for impact-angle control. Second, an impact-time control guidance law is derived based on desired error dynamics, enforcing the impact-time constraint through the finite-time convergence of the time-to-go error. This controller is derived using optimal control theory to minimize a weighted quadratic cost functional, and its finite-time stability is rigorously verified through Lyapunov analysis. The integrated guidance law, which incorporates the FOV constraint, satisfies all prescribed constraints and demonstrates robust performance, as validated through extensive numerical simulations.