多扰动下充液柔性航天器动力学响应及其颤动抑制策略研究

The jitter would occur when an in-orbit fuel-filled spacecrafts with flexible appendage subjected to the disturbances. These disturbances on spacecrafts include reaction or momentum wheels, control moment gyros, solar drive motors, thruster firing and fuel sloshing in tank. This jitter would easily affect the stability of spacecraft and cause the failure of attitude transition and orbit change for spacecraft. In this project, the dynamic characteristics of a fuel-filled flexible spacecraft subjected to multi-disturbance are discussed by numerical and analytical method, and the hybrid control method is investigated to suppress the jitter of the spacecraft. In the process of dynamics modeling, the couple effects between the nonlinear sloshing of liquid fuel and the large deflection of flexible appendage are fully considered. The analytical solution of the coupling system is studied using the classical theory of nonlinear dynamics, and the effects of the system parameters on the stability of the spacecraft are analyzed. The hybrid control method is developed to suppress the jitter of the spacecraft, at the same time, reduce the amplitude of the flexible appendage vibration and liquid sloshing. The hybrid controller is designed by smart adaptive feedback control strategy and piezoelectric layers control law, the numerical simulation method will be used to verify the control precision and effectiveness of the proposed hybrid controller. This research will provide the theoretical supports for the design and control of the fuel-filled flexible spacecraft.

充液柔性航天器在轨运行过程中，会受到多种扰动的影响从而发生颤动，扰动的来源主要有：航天器内置动量轮；控制力矩陀螺；热冲击；推进剂点火过程引起的振动；贮液箱体中液体燃料的晃动等。这种颤动会严重影响航天器的稳定性，甚至导致航天器飞行任务的失败。本项目以大型充液柔性航天器为研究背景，应用数值和解析的方法分析多扰动下航天器系统的动力学特性，并进行颤动抑制复合策略的研究。建模过程中考虑液体燃料非线性晃动及挠性附件大变形对耦合系统的影响，引入非线性动力学理论对航天器耦合系统进行解析分析，探讨各种参数对航天器结构稳定性的影响。然后深入研究复合控制策略，在快速有效抑制航天器本体颤动的同时控制挠性结构的振动及液体燃料的晃动，复合控制器设计过程中结合智能自适应反馈控制理论及压电智能控制方法，并应用数值方法验证控制器的有效性。研究结果将为航天器的设计及控制提供理论储备。

为了完成长时间复杂的航天任务，要求现代航天器有灵活的机动性能及较高的稳定性，因此需要对航天器在轨运行过程中残余振动进行严格控制。本项目主要进行多扰动下三轴稳定充液柔性航天器动力学建模与控制策略研究。课题在以下几个方面取得了进展：(1) 在动力学建模过程中，充分考虑了刚-柔-液-控耦合问题。引入了液体多模态晃动，及挠性附件几何大变形。(2) 利用数值法和解析法研究了多扰动下航天器动态特性，携带复杂储液腔体及多腔体充液航天器液体燃料晃动的动态特性，柔性附件大挠度非线性振动对航天器姿态的影响。(3) 利用自适应滑模控制理论、压电智能控制理论与输入成型技术相结合设计复合控制策略，所设计的复合控制器不依赖于航天器的惯性参数，对外部扰动具有很好的鲁棒性，在完成高精度姿态机动的同时抑制了挠性帆板振动及液体燃料晃动。本项目研究成果将为复杂航天器的姿态控制设计提供理论储备。