Multiobjective Optimization of Steady-State Cruise Trajectory for a Hypersonic Vehicle

Cruise trajectory optimization for a hypersonic vehicle is a standard optimal control problem. With the use of the direct shooting (DS) method, it is converted to a NLP problem first. Then, the steady-state cruise dynamic equations are described. To solve the multiobjective problem related to the steady-state cruise trajectory optimization, one of the directed search domain (DSD) algorithm, DSD-II, is applied. The main steps are introduced. Furthermore, the optimization model is introduced. The design variables are the altitude, Mach number at the initial cruise moment, and the angle of attack during the cruise period. Finally, three test cases with different cruise Mach numbers are presented. It is shown from the numerical results that DSD-II can generate a quasi-evenly distributed Pareto set and effectively solve the multiobjective optimization problem. In addition, comparisons are made on the feasible cruise altitude zone, minimal cruise angle of attack, and maximal cruise time among the three cases. Relevant conclusions are drawn for reference.