Article
Improved Adaptive Augmentation Control for a Flexible
Launch Vehicle with Elastic Vibration
Aiping Pang
1,2
, Hongbo Zhou
1,2
, Wenjie Cai
3
and Jing Zhang
1,
*
Citation: Pang, A.; Zhou, H.; Cai, W.;
Zhang, J. Improved Adaptive
Augmentation Control for a Flexible
Launch Vehicle with Elastic Vibration.
Entropy 2021, 23, 1058. https://
doi.org/10.3390/e23081058
Academic Editors: Quanmin Zhu,
Giuseppe Fusco, Jing Na,
Weicun Zhang and Ahmad
Taher Azar
Received: 16 June 2021
Accepted: 10 August 2021
Published: 16 August 2021
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4.0/).
1
College of Electrical Engineering, Guizhou University, Guiyang 550025, China; appang@gzu.edu.cn (A.P.);
hit_zhb@163.com (H.Z.)
2
Guizhou Provincial Key Laboratory of Internet + Intelligent Manufacturing, Guiyang 550025, China
3
China Academy of Launch Vehicle Technology, Beijing 100076, China; caiwenjie217@126.com
* Correspondence: zhangjingguizhou@126.com
Abstract:
The continuous development of spacecraft with large flexible structures has resulted in an
increase in the mass and aspect ratio of launch vehicles, while the wide application of lightweight
materials in the aerospace field has increased the flexible modes of launch vehicles. In order to solve
the problem of deviation from the nominal control or even destabilization of the system caused by
uncertainties such as unknown or unmodelled dynamics, frequency perturbation of the flexible mode,
changes in its own parameters, and external environmental disturbances during the flight of such
large-scale flexible launch vehicles with simultaneous structural deformation, rigid-elastic coupling
and multimodal vibrations, an improved adaptive augmentation control method based on model
reference adaption, and spectral damping is proposed in this paper, including a basic PD controller,
a reference model, and an adaptive gain adjustment based on spectral damping. The baseline PD
controller was used for flight attitude control in the nominal state. In the non-nominal state, the
spectral dampers in the adaptive gain adjustment law extracted and processed the high-frequency
signal from the tracking error and control-command error between the reference model and the actual
system to generate the adaptive gain. The adjustment gain was multiplied by the baseline controller
gain to increase/decrease the overall gain of the system to improve the system’s performance and
robust stability, so that the system had the ability to return to the nominal state when it was affected
by various uncertainties and deviated from the nominal state, or even destabilized.
Keywords: multiplicative adaptation; gain adjustment; spectral damping; robust stability
1. Introduction
As the exploration of the space environment progresses, the missions of spacecraft
exploration become more and more diversified, and as the application of polymer materials
in the space field progresses, the structure of spacecraft is gradually developing towards
large and flexible structures. In order to carry these large and flexible-structure spacecraft,
launch vehicles with a large carrying capacity have become an inevitable requirement of
space-development strategies [
1
]. At the same time, the lightweight polymer material used
in the body of launch vehicles has increased the flexible mode of the vehicles, leading to
the presence of structural deformation, rigid body-elastic vibration coupling, multi-modal
vibration, and other characteristics of the body at the same time. These factors make the
attitude control of launch vehicles subject to oscillations and difficult to attenuate, or even
lead to system instability, which poses a new challenge to the reliability and robustness of
launch vehicles [2].
For high-risk aerospace applications, both government and industry rely heavily on
classical control theory, and gain-scheduling PID control is still the mainstream control
method for current launch vehicles, due to the advantages of its simple structure, good
anti-interference, and ease of analysis in the time domain (or frequency domain). Typical
applications include the Saturn V and Space Shuttle of the United States, the Ariane of
Entropy 2021, 23, 1058. https://doi.org/10.3390/e23081058 https://www.mdpi.com/journal/entropy
