Accurate Real-Time Prediction Guidance Using Numerical Integration for Reentry Spacecraft

Abstract

In an advanced concept study of the Japanese manned reentry capsule, the capsule attempts to land on the Japanese mainland. For this purpose, the targeted reentry guidance accuracy is to within 1 km at the point of parachute deployment. To meet this high requirement, we have been developing accurate real-time prediction guidance using numerical integration for reentry spacecraft. This guidance method is an explicit guidance law using real-time numerical integration to predict accurate range during reentry flight. The range prediction algorithm is specially designed to reduce computational load while retaining guidance accuracy. To improve reentry guidance accuracy, we also use IMU-GPSST integration navigation, measured wind information for range prediction, and terminal reentry guidance for reentry guidance. This paper proposes real-time prediction guidance using numerical integration and evaluates the computational load and reentry guidance accuracy of guidance law in comparison with existing reentry guidance laws such as the valuable gain method and the closed form method. This paper also describes methods used in the proposed reentry guidance to improve reentry guidance accuracy, IMU-GPS-ST integration navigation, accurate range prediction using measured upper-level wind information, and terminal reentry guidance, and evaluates guidance accuracy under the worst-case conditions and maximum errors.