Skip entry guidance using numerical predictor–corrector and patched corridor

Abstract

This paper presents a skip entry guidance algorithm that uses a numerical predictor–corrector and a patched corridor for low-lifting capsules returning from the Moon. The longitudinal and lateral channels are assumed to be decoupled. The bank angle magnitude profile is parameterized using piecewise linear segments with respect to a normalized energy. The shape of the bank-vs-energy profile is determined using a single piecewise-defined variable. The predicted longitudinal bias is nullified using a false position method. The adverse effects of aerodynamic and atmospheric uncertainties are mitigated using an on-board estimating strategy during the trajectory prediction. A patched corridor is devised to manage the lateral state based on analytical derivations and reasonable approximations. The sign of the bank angle is reversed when the boundary of the patched corridor is violated. Dispersed simulations are implemented in a three-degree-of-freedom dynamical context, and the results demonstrate the high performance of the proposed guidance algorithm under stressful testing conditions.