An Integrated Decoupling Device for Azimuth Control of a Balloon-Borne Gondola

Honghui Wang,Xiaojun Yu,Shicheng Liang,Zeming Fan,Zhaohui Yuan,Juan Wu

doi:10.1155/2020/6718273

Honghui Wang, Xiaojun Yu + Show 4 more

Open Access

https://doi.org/10.1155/2020/6718273

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Abstract

Controlling and maintaining the orientation of the balloon-borne gondola for high-altitude flight is a prerequisite for ensuring the pointing control of observation instruments. When the balloon-borne gondola is flying in the stratosphere of the atmosphere, the existing external interferences will be converted into the coupling moment to the azimuth control system. Meanwhile, those uncertain factors and the frictional nonlinearity of the control system will also cause a certain magnitude of coupling moment. The existence of such coupling moment largely impacts on the accuracy and stability of the orientation control for the angular momentum exchange devices of the balloon-borne gondola. To address such an issue, this paper proposes and implements a novel type of integrated decoupler device. With this decoupler adopted, the aziDmuth control system could sense the existence of coupling torque and azimuth fluctuations quickly and suppress the influences of external interference, uncertain factors, and system structure nonlinearity on the azimuth control effectively, thereby improving the control accuracy of the azimuth control system. Both simulations and experiments are conducted to verify the effectiveness of the proposed device. The results show that the integration of the decoupler and the controller of the azimuth control system provide the azimuth control of the balloon-borne gondola with high accuracy and stability. Such a decoupler device design has a broad potential and could not only be used for balloon-borne gondola control but also could be applied onto other control systems using angular momentum exchange devices as actuators.

Highlights

Those reported systems achieved satisfactory control precision, there still exist a number of problems after integrating the azimuth control system onto the ball-carrying gondola platform, due to the various external factors and the inherent system nonlinearities [11, 12]
Last but not least, during the transient state when the gondola orientation is modified at its transient state, the gondola azimuthal control may fail due to the frictional nonlinearity of the system structure, and such a state may last for a while until the influences of the frictional torque are eliminated with the increased control torque [16, 17]
The decoupler is desired to compensate the coupling torque caused by the frictional nonlinearity of the control system structure such that the available control torque of the azimuth control system can be extracted more timely [20, 21]

Summary

Introduction

Those reported systems achieved satisfactory control precision, there still exist a number of problems after integrating the azimuth control system onto the ball-carrying gondola platform, due to the various external factors and the inherent system nonlinearities [11, 12]. E main contributions of our study could be summarized into two aspects: first, both the formation and the influences of the coupling torque introduced by the nonlinearities and uncertain disturbances are theoretically analyzed when the balloon-borne gondola is working in the air, and secondly, an integrated decoupler that could help avoid velocity saturation of the flywheel motor is proposed and experimentally verified, which lays a good foundation for the azimuth control of the balloon-borne gondola.

Results

Conclusion