航天器交会对接近距离姿轨一体化控制方法分析.docx

摘要
失效的目标航天器在空间做自由翻滚运动,其姿态与位置随时间快速变化,这给交会对接、在轨修复、燃料加注等航天任务的研究带来了新的问题和挑战。与这样非合作目标交会对接技术因其在航天任务中的广泛应用前景和数学模型上的强耦合性和强非线性,近年来逐渐成为控制领域的热点和难点。本文以与空间内自由翻滚目标交会对接近距离段的相对位置和相对姿态控制技术为课题展开研究,首先针对近距离段的姿态跟踪问题设计了有限时间姿态控制器,然后针对考虑姿轨耦合的交会对接任务设计姿轨一体化控制器,并且考虑了外力产生的干扰、推力器、飞轮等执行机构故障和控制输出饱和等问题。本论文主要包括以下内容:
针对交会对接中执行器存在故障与控制受限刚体航天器的姿态跟踪控制问题,提出一类基于新型指数形式的非奇异快速滑模面(ENFTSM)与趋近律的姿态容错控制器设计方法。当部分推力器发生故障时,假设剩余推力器具有输出饱和特性且能提供足够推力保证航天器执行任务,相比传统的终端滑模控制器,本文设计的有限时间控制器不仅能使系统状态以更快的速度收敛到平衡点,且不需要对执行器故障信息进行实时的检测和分离。基于 Lyapunov 方法证明本文设计的控制器能保证闭环系统稳定,且能有效地抑制外部干扰、控制受限和执行器故障等约束。
针对与自由翻滚航天器交会对接近距离段的姿轨强耦合控制问题,基于滑模自适应控制方法设计了一类六自由度姿轨一体化控制器,且在其数学表达式中显式地引入执行机构的饱和幅值,从而确保控制输出在其要求界的范围内;考虑到追踪航天器姿轨运动中存在外干扰、参数不确定性、强耦合非线性等工程实际问题,设计的控制器可以使闭环控制系统对这类干扰具有 L2 增益稳定,并基于 Lyapunov 稳定原理证明了闭环系统的稳定性与系统性能。最后仿真说明在与目标自由翻滚航天器进行交会对接时,本文设计的控制器可以对追踪航天器相对位置和姿态同时进行快速、高精度的控制,且具有良好的性能。
关键词:航天器;交会对接;耦合控制;控制受限;容错控制;终端滑模
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Abstract
Approaching and docking autonomously with a freely tumbling spacecraft, whose position and attitude are time-varying, leads new challenges to space missions, such as repairing a failure satellite, refueling a powerless satellite and so on. The technology of approaching and docking to an out-of-control target spacecraft, which has a widespread application prospect in the future spacecraft mission, and whose mathematic model is strongly coupled and nonlinear, is ing a hot and difficult problem. In this dissertation, relative position and relative attitude controllers are investigated for approaching and docking within a short distance. In the first, a finite-time controller is proposed for the attitude tracking control system. Then a relative position and attitude coupled controller is developed for approaching and docking. The main contents of the dissertation are as follows:
An exponent nonsingular fast terminal sliding mode (ENFTSM) control law is investigated in this paper for a rigid spacecraft with redundant thrusters in which thruster faults, and control input saturation as well as external disturbances have t