Gravity-Turn-Assisted Optimal Guidance Law

This chapter proposes a new optimal guidance law that directly utilizes, instead of compensating, the gravity for accelerating missiles. The desired collision triangle that considers both gravity and vehicle’s axial acceleration is analytically derived based on geometric conditions. The concept of instantaneous zero-effort-miss is introduced to allow for analytical guidance command derivation. The proposed optimal guidance law is derived by using the optimal error dynamics proposed in Chap. 2. The relationships of the proposed formulation with conventional PNG and guidance-to-collision (G2C) are analyzed and the results show that the proposed guidance law encompasses previously suggested approaches. The significant contribution of the proposed guidance law lies in that it ensures zero final guidance command and enables energy saving with the aid of utilizing gravity turn. Nonlinear numerical simulations clearly demonstrate the effectiveness of the proposed approach.