Enhanced Procedures for Direct Trajectory Optimization Using Nonlinear Programming and Implicit Integration

Abstract

Trajectory optimization is key to the design and analysis of aerospace vehicles. The use of implicit integration combined with modern nonlinear programming packages has proven to be an effective technique for trajectory optimization. To provide greater fidelity and robustness, enhanced procedures have been developed. General procedures are presented for implicit integration schemes of arbitrary order, automatic variable scaling and grid refinement. The implicit integration methods of interest are collocation, quadrature and pseudo-spectral integration. Computation experiences applying and comparing these methods to interplanetary spacecraft and aircraft problems are given. These procedures have demonstrated substantial improvements in integration accuracy and robust operations.