复杂限制条件下电动力绳系离轨系统动力学分析及控制

This project is motivated by the requirement of removing space debris from the Earth orbits, and focuses on the dynamics and control of the deorbiting electrodynamic tether systems. The research topics of concern mainly include the problems of dynamic modeling and analysis, state estimation, controller design and ground-based experiments, etc. The research is based on a tight combination of theoretical, numerical and experimental studies, with a full consideration of the complex restrictions. The main innovations of the research include: for the problems of dynamic modeling, state observation and controller design, a non-singular description of attitude motions is proposed to replace the conventional method based on dual angular parameters; parameter estimation and disturbance observation are performed to improve the robustness of the deployment control law; online quasi-linearization iterations are exploited for efficiently solving the problems of state estimation and model predictive deorbiting control, etc. The objectives and aims of the research include: building nonlinear dynamic models for the deorbiting electrodynamic tether systems, developing numerical schemes of high precision for simulation verification, and revealing the complex dynamic behaviors due to the time-varying nonlinear characteristics and the multi-physics environment; accounting for the restrictions of measurement and actuation, the constraints of state and control, and the limiting computation resources, proposing the strategies of state observation and estimation which are efficient and easy to implement, and finding reliable and robust control schemes for the deployment and deorbiting processes; developing a ground-based experimental system based on the dynamic similarity of the in-orbit and ground systems for verifying the main results of the research.

本项目以地球轨道空间碎片清理需求为背景，从动力学建模与分析、状态估计、控制器设计及地面模拟实验等方面，研究电动力绳系离轨系统的动力学与控制问题。特色在于理论、数值和实验研究的紧密结合，尤其对复杂限制条件的综合。主要创新：打破基于双角参数的研究惯例，以非奇异姿态运动描述框架开展动力学简化建模、状态观测和控制器设计研究；以参数辨识和扰动观测等方法提高释放控制鲁棒性；以在线拟线性迭代实现移动区间状态估计和模型预测离轨控制问题的高效求解。本项目旨在建立电动力绳系离轨系统的非线性动力学模型，发展高精度数值仿真验证方法，揭示时变非线性特性及多物理场环境导致的复杂动力学行为；考虑测量条件、作动方式、控制/状态约束、计算资源等限制，提出易于实现的高效状态观测和估计方法，实现释放展开及离轨过程的可靠控制；建立天-地动力学相似模拟实验系统，验证主要结果。

电动力绳系离轨是一项具有广阔应用前景的前沿空间技术。本项目综合采用理论分析、数值计算和地面模拟实验方法，开展了电动力绳系离轨系统动力学与控制研究。已按计划开展项目研究，主要成果如下：建立了电动力绳系航天器的非奇异动力学模型，设计了解析形式的电流饱和反馈控制律，提出了基于模型预测控制的电动力绳起旋控制律，设计了基于非奇异模型和向量测量的系绳角速度观测器；分析了绳系卫星系统的非线性共振行为，建立了柔性系绳与航天器的刚柔耦合动力学模型，发展了计入参数不确定性的动力学分析方法；针对绳系航天器的释放控制问题，提出了以模糊动力学模型为基础的鲁棒拉力控制律，发展了电流和拉力的联合控制方法，设计了基于轨迹跟踪的拉力控制律及端部卫星的姿态控制律；基于非奇异姿态动力学模型，发展了非线性模型预测控制律的深度学习方法；基于时间尺度分离的概念和最优控制理论，提出了电动力绳系航天器长时间离轨的反馈控制方法；设计了基于视觉的绳系卫星系绳摆角测量方法和子星弹射机构，建立了电动力绳系航天器的地面模拟实验系统，对系绳摆动控制律进行了验证。本课题研究结果为电动力绳系系统动力学建模/分析、释放/离轨控制提供了新的理论和技术。