Coordinated control of pressure difference and rising velocity for stratospheric airship with thermal effects

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.