Field-of-View-Reduced Impact Angle Guidance Law via Range Shaping Approach

This paper addresses the impact angle guidance problem for low-cost missiles equipped with strap-down seekers that require a reduced field-of-view (FOV) limit. The objective is to obtain a lightweight, robust, and applicable constrained homing guidance law. As a cornerstone, the missile-target range is reshaped by polynomials in the look angle-related variable. Then, constrained guidance laws are derived with analytical formulations via transforming the model and solving boundary conditions of different shaping forms. The reduced FOV limit is achieved by restricting the shaping profile's variation rate as negative. To improve the model-induced guidance robustness, the shaping deviation is eliminated via a compensation law. Both the shaping-based and robust guidance laws are generalized as PNG laws with time-varying gains governed by the reference range profiles. Furthermore, the achievable impact angle sets are derived such that proper constraints can be selected for blind guess avoidance and feasible command generation. Notably, the analytical formulation, a priori set determination, robust compensation, and PNG generalization meet the previously mentioned objective in unison. Finally, extensive numerical simulations and Monte Carlo tests are conducted to verify the guidance performance and robustness.