Development of a finite difference neighboring optimal control law and application to the optimal landing of a reusable launch vehicle

A new neighboring optimal control methodology is developed and applied to the fuel-optimal landing of a reusable launch vehicle. Two new methods, both based on perturbation analysis, are explored. A fast open-loop optimal trajectory solver is developed to handle the numerically intensive perturbation analysis phase of control law synthesis. High accuracy closed-loop simulation of both the optimal control law and plant model shows that the optimal control law is robust for a number of different off-nominal conditions.