Trajectory optimization and control of stratospheric airship in cruising

Abstract

Stratospheric airships are important platforms for near-space enduring cruising capability for several applications. Since energy shortage is one of major limiting factors in stratospheric airship, it is crucial to develop novel methods to reduce the requirement on energy systems. In this article, optimal trajectory of stratospheric airship in gradient wind fields is investigated in order to reduce energy consumption. First, polynomial expressions for wind gradients are assumed, and three-dimensional point mass airship equations of motion are used. Then the variety characters of energy for stratospheric airship are studied, the minimum power output of power system is taken as the optimizing target, and collocation approach is used to convert the trajectory optimization problem into parameters optimization. The characters of stratospheric airship’s cruising in three typical wind field are analyzed, including control and state parameters time histories, power changes for airship system, and so on. This research work shows that the greater the wind gradient, the more favorable to reduce energy consumptions, but the speed of the gradient wind cannot be too high.