Predictor–Feedback Entry Guidance for Super Heavy-Lift Launch Vehicles’ Second Stage

This paper investigates entry guidance for the second stage of super heavy-lift launch vehicles, which are liftingbody vehicles equipped with aerodynamic control surfaces. The vehicle performs a gliding entry, demanding very high targeting accuracy. Existing methods relying solely on bank-angle control typically achieve only kilometer-level targeting accuracy. This paper proposes a predictor–feedback entry guidance method realizing meter-level targeting accuracy. The high accuracy necessitates the use of both angle of attack and bank angle as controls. However, this leads to a difficulty in that the controls have a strong coupled effect on the downrange and cross-range errors. To address this, the proposed method first applies reference control profiles to predict the terminal position error, then introduces an appropriate transformation to obtain a transformed terminal position error. This error serves as feedback to the designed guidance laws for computing the control commands. A unique property is the near decoupling of the controls’ influence on the transformed error, enabling significant improvement in targeting accuracy. Path constraints on heating rate, dynamic pressure, and load factor are also incorporated via reference control refinement. Notably, the proposed entry guidance’s stability is theoretically established. Numerical results clearly demonstrate the effectiveness, strong robustness, and high targeting accuracy of the proposed method.