Unsaturated Optimal Guidance Law for Impact Angle and Acceleration Constraints

Most research on impact angle control has not addressed acceleration constraints, as it assumes that maneuverability is sufficient. However, when guidance commands are saturated due to aerodynamic or structural loads, the miss distance and impact angle errors can be significantly large. This paper presents an unsaturated optimal guidance law that satisfies acceleration constraints in a period of full flight. The proposed guidance law is established by designing a weighting function based on the closed-form solution of a time-to-go weighted optimal impact angle guidance law. This strategy theoretically guarantees optimality and convergence under acceleration constraints. Numerical simulations are conducted to validate the proposed guidance law.