推力方向制約付き月軟着陸の最適化

Abstract

The purpose of this paper is to obtain the optimum trajectory for the fuel minimum guidance phase of lunar soft landing experiments NASDA is planning. In this phase the lander descends to a few km altitude from 15km altitude realized by the Hohmann transfer from the circular orbit of 100km altitude. Characteristics of the phase are thrust direction constraints near the terminal point, which are (A) thrust direction at the terminal point must be vertical and (B) change rate of the thrust direction must be smaller than the specified value. It was obtained the minimum thrust should be used for the latter half of the interval just before the terminal point where the thrust direction is changing largely. The optimum thrust direction except the region where the thrust direction is changing largely coincided with the one for no constraints. This fact will ease the derivation of guidance law.