[论文解读] On Attitude Recovery of Spacecraft using Nonlinear Control

S. Tafazoli|arXiv (Cornell University)|Dec 2, 2020

Space Satellite Systems and Control被引用 6

一句话总结

本博士论文提出了一种基于输入-输出反馈线性化的非线性控制方法，用于柔性航天器的姿态恢复。通过采用混合坐标建模航天器，并将系统划分为外部线性动态和内部非线性动态，该方法实现了局部渐近稳定的零动态，并在存在不确定性的情况下表现出鲁棒性能，其有效性通过在具有柔性附件的刚性中心舱体上进行的大量仿真得到验证。

ABSTRACT

The general objective of this Ph.D. thesis is to study the dynamics and control of rigid and flexible spacecraft supported by a high-fidelity numerical simulation environment. The demand for greater attitude pointing precision, attitude maneuvering or recovery with the increased use of lightweight and flexible materials necessitates the consideration of flexible dynamics in the control strategy. These highly nonlinear dynamics which increase the order of the system are extremely difficult to model with high degree of accuracy. A general model for attitude and flexible dynamics for a class of spacecraft is hence derived in detail based on the so-called hybrid coordinates approach. The spacecraft considered has a star topology with a rigid central bus and flexible plate-type appendages. Given that the flexible spacecraft is under-actuated, the input-output feedback linearization technique is specifically used to partition the system into two distinct parts, namely an external linear system and an internal unobservable nonlinear system. A general internal/zero dynamics theorem for a class of nonlinear systems is proved and then applied to a flexible spacecraft which results in a linear asymptotically stable zero dynamics. The overall closed-loop stability of the flexible spacecraft is also analyzed rigorously and shown to be locally asymptotically stable using the Lyapunov theory. The robustness of the controller against modeling and parametric uncertainties is examined through extensive numerical simulations. Overall, the feedback linearization control scheme has been proven to be feasible and efficient for the attitude recovery of a spacecraft and has also become front and center in other application areas in the recent years.

研究动机与目标

• 开发一种高保真的控制策略，用于柔性航天器，以提升姿态指向精度。
• 解决轻质柔性材料在航天器设计中带来的非线性、高阶动力学挑战。
• 确保欠驱动柔性航天器系统的稳定姿态恢复。
• 利用李雅普诺夫理论严格分析闭环稳定性。
• 评估控制器在参数和建模不确定性下的鲁棒性。

提出的方法

• 采用混合坐标方法，为具有刚性中心舱体和板式柔性附件的航天器，推导出一种通用的姿态与柔性动力学模型。
• 应用输入-输出反馈线性化，将系统划分为外部线性系统和内部不可观测的非线性系统。
• 证明并应用非线性系统的一般内部/零动态定理于柔性航天器模型。
• 证明零动态为线性且渐近稳定，从而确保整个系统的稳定性。
• 基于李雅普诺夫的分析证实了闭环系统的局部渐近稳定性。
• 进行了大量数值仿真，以评估控制器在建模和参数不确定性下的鲁棒性。

实验结果

研究问题

• RQ1 如何通过高保真方法准确建模柔性航天器动力学以支持控制设计？
• RQ2 反馈线性化能否有效稳定欠驱动柔性航天器的姿态恢复？
• RQ3 柔性航天器系统中内部零动态的稳定性行为如何？
• RQ4 控制器在参数和建模不确定性下的性能表现如何？
• RQ5 所提出的控制方案在实际运行条件下能实现多大程度的鲁棒性？

主要发现

• 柔性航天器的内部零动态被证明为线性且渐近稳定，从而确保了整个系统的稳定性。
• 闭环系统表现出局部渐近稳定性，该结论通过李雅普诺夫理论得到严格证明。
• 尽管系统具有高度非线性和因柔性带来的高阶特性，反馈线性化控制方案仍成功实现了姿态恢复。
• 在数值仿真中，控制器在各种参数和建模不确定性下表现出鲁棒性能。
• 该方法在姿态恢复方面具有可行性与高效性，并已在更广泛的应用领域获得关注。
• 本研究为将反馈线性化方法应用于复杂柔性航天器系统奠定了基础，具有实际工程应用价值。