A Practical Optimal Guidance Scheme Under Impact Angle and Terminal Acceleration Constraints

Abstract

This paper proposes a practical optimal guidance law that can handle terminal angle and acceleration constraints while providing robustness against uncertainty in autopilot dynamics. Building upon a well-established linear-quadratic optimal guidance framework, we first derive an energy-minimizing guidance scheme that nullifies terminal acceleration called optimal guidance law with impact angle and terminal acceleration constraints (OGL–IATA). Then, a practical modification to OGL–IATA is proposed to deal with the stability degradation of OGL–IATA due to unmodeled high-order autopilot dynamics. The modification primarily features feedback of pseudo-acceleration that is computed by passing the true acceleration signal through approximate missile dynamics; this simple modification is demonstrated to improve the stability margin of the guidance loop. Numerical examples of nonlinear engagement kinematics demonstrate the performance and the robustness characteristics of the proposed practical guidance scheme.