Coordinated Control of Pressure Difference and Rising Velocity for Stratospheric Airship with Thermal Effects

Luhe Hong,Weiyao Lan,Hui-Yu Jin,Xianwu Lin

doi:10.1155/2015/923156

Abstract

Ascending control of stratospheric airship is a challenging control problem, especially if both the rising velocity and the pressure difference between the inside and outside of the airship are required to be controlled simultaneously during ascending. In this paper, a coordinated scheme to control pressure difference and rising velocity of stratospheric airship with vector thrust is presented. With the control scheme, the airship maintains the pressure difference by exhausting air with feedback control. At the same time, the supplemental thrust is generated to compensate the buoyancy fluctuation caused by exhausting air so that the airship’s vertical velocity can track a given reference trajectory. Simulations show that the coordinated control scheme ensures that the airship rises to the altitude of 20 km steadily and rapidly while the pressure difference is always in the safe range. Furthermore, the control scheme is robust enough to the thermal disturbance caused by solar radiation and other thermal processes, which is calculated with partial differential equations.

Highlights

Stratospheric airship, a low-speed near space aerocraft, mainly relies on static buoyancy to ascend and maintain itself in working height [1]
The velocity tracks the reference trajectory well, while the pressure difference is maintained in the safe range
Because the thermal models, such as solar radiation and membrane temperature change, are not used to design the controllers, these results show that the control scheme can achieve the coordinated control of pressure difference and rising velocity and has good robustness against the thermodynamic disturbance

Summary

Introduction

Stratospheric airship, a low-speed near space aerocraft, mainly relies on static buoyancy to ascend and maintain itself in working height [1]. Rising to the resident height safely is a prerequisite for stratospheric airship to work properly [3]. The stratospheric airship exhausts inner air continuously to guarantee that the pressure inside the airship is slightly greater than the atmospheric pressure outside. If the internal pressure is not enough, the airship balloon may be deflated by external atmospheric pressure, resulting in an overall structural deformation. If the internal pressure is too large, the balloon may be in excessive tension even rupture. To control the pressure difference between inside and outside of the airship is extremely important throughout the whole process of ascending [4]

Methods

Results

Conclusion