Development of an Integrated Design Environment for Optimal Ascent Trajectory Planning

Abstract

Current practical methods of pitch programming design for multi-stage launch and ballistic vehicles suffer from several deficiencies. For many applications they are often determined for various phases of ascent trajectory utilizing simplified dynamics that results in non-optimal trajectories. Trial-and-error design techniques coupled with flight simulation usually results in a more accurate pitch program, but that may not satisfy all the required constraints simultaneously and is also very time consuming. In this study, an integrated design environment is developed which enables a novice designer to generate optimal pitch program for the whole part of the ascent trajectory while satisfying all the required flight path constraints as well as the final time boundary conditions. Since, the preset guidance program is naturally known as an open-loop steering program, this method utilizes optimal control theory using full nonlinear system state equations together with a functional performance index to determine the optimal steering command. Evaluation of the proposed technique is demonstrated through application on a typical two stage ballistic vehicle, for which the resulting trajectory fully satisfies all the flight related and final time constraints.

Keywords

• multi-stage flight vehicle
• pitch program
• optimal design
• optimal control theory