Constrained Predictor-Corrector Entry Guidance

Abstract

In this paper we develop a numerical predictor-corrector entry guidance algorithm for vehicles with medium to higher lifting capability. A major dierence between the current algorithm and existing predictor-corrector algorithms is that the current algorithm has the ability to enforce all inequality trajectory constraints commonly seen in entry ight. The enabling mechanism is the so-called quasi-equilibrium glide condition (QEGC). The QEGC allows convenient translation of the path constraints in the velocity-altitude space into the energy-dependent upper and lower bounds for the magnitude of the bank angle. As such, the algorithm is able to enforce the path constraints without suering the usual side eects of increasing complexity and degraded robustness. Another unique feature of the current algorithm is on-line adaptation of a parameter in the lateral guidance logic so that the nal heading alignment oset is tightly regulated. Extensive dispersion simulation results are presented to demonstrate the eectiveness and precision of the algorithm.