液体多模态晃动柔性航天器姿态机动复合控制研究

发布时间：2018-04-27 11:45

本文选题：充液柔性航天器 + 大角度姿态机动　；参考：《北京理工大学》2015年博士论文

【摘要】：为了完成长时间复杂的航天任务，航天器需要携带大量的液体燃料，燃料质量的增加不但容易导致航天器储液箱液体发生晃动，还会与航天器的姿态运动及柔性附件振动发生耦合从而影响航天器的稳定性，甚至可能导致航天器飞行任务失败。因此，研究大型充液柔性航天器的姿态稳定性以及液体晃动与挠性附件的振动抑制至关重要。本课题主要对考虑液体多模态晃动的大型充液柔性航天器建模及大角度姿态机动复合控制策略进行了深入的研究。在动力学建模过程中，充分考虑了刚-液耦合及刚-液-柔耦合的问题。论文的研究内容主要包括以下几方面。 (1)应用动量矩定理建立了三轴稳定充液航天器耦合系统动力学方程。将晃动液体燃料等效为二阶弹簧-质量模型，针对充液航天器大角度姿态机动问题，设计了基于自适应动态输出反馈控制器及加入多模态前馈输入成型技术的复合控制器，数值模拟结果显示，控制器不依赖于航天器的惯性参数，对于外部干扰具有很好的鲁棒性；多模态ZVD输入成型器对于液体燃料的晃动具有很好的抑制效果。 (2)针对部分充液航天器耦合系统为典型的欠驱动系统这一特性，，设计了欠驱动自适应滑模控制器。采用Lyapunov方法分析了滑动模态的存在性及稳定性，并且针对不能直接得到等效液体弹簧质量模型晃动模态及速度的情形，设计了基于液体晃动方程的状态观测器，用于估计液体晃动的前两阶晃动模态，然后在控制系统中加入输入成型前馈控制技术从而设计出相应的复合控制器。仿真结果表明，自适应滑模控制方法与传统控制方法相比具有很好的控制精度，对参数不确定性具有很强的鲁棒性。 (3)研究了光压扰动影响下挠性充液航天器的姿态机动控制问题。以带有单个挠性帆板的在轨运行充液航天器为研究对象，分析其进出太阳半影区过程中，因太阳光压改变引起的温度骤然变化而产生的热弯矩对航天器系统稳定性的影响。根据Euler-Bernoulli梁理论，利用拉格朗日方法建立了挠性太阳帆板的动力学方程，应用动量矩定理建立刚体航天器及晃动液体的动力学方程，计算结果表明：太阳光压引起的热扰动对于航天器的姿态运动精度的影响不容忽视。之后，针对此类存在参数不确定、外部干扰以及控制力矩受限的复杂航天器大角度姿态机动问题，设计了自适应滑模控制律。并且将压电材料应用到挠性结构振动的主动控制中，设计了内回路PPF正位置反馈控制器。仿真结果表明，在考虑非线性饱和约束条件下，所设计的复合控制策略可以达到姿态控制精度的要求并且有效抑制挠性附件的振动及液体的晃动。 (4)研究了带有大挠性结构充液航天器耦合系统的动力学及控制问题。假设挠性附件为非线性Euler-Bernoulli大变形梁模型，应用拉格朗日方法建立了其动力学方程。鉴于控制方程极为复杂，引入了奇异摄动理论将控制系统分解为慢变子系统及快变子系统。对于慢变子系统，为了提高控制精度，设计了推力器与动量轮的混合控制策略；对于快变系统应用压电智能元件设计Lyapunov控制律，在很短的时间内有效地抑制挠性结构的振动。数值仿真结果很好验证了控制策略的有效性。
[Abstract]:In order to accomplish long - term and complex space missions , the spacecraft needs to carry a large amount of liquid fuel , which not only can cause the liquid of the spacecraft liquid storage tank to shake , but also can be coupled with the attitude motion of the spacecraft and the vibration of the flexible accessory so as to affect the stability of the spacecraft and even lead to failure of the spacecraft flight mission . Therefore , it is important to study the attitude stability of the large liquid - filled flexible spacecraft and the vibration suppression of the liquid shaking and the flexible attachment .

In this paper , the large - scale liquid - filled flexible spacecraft model considering multi - modal slosh of liquid and the complex control strategy of large - angle attitude maneuver are studied in detail . In the process of dynamic modeling , the problems of rigid - liquid coupling and rigid - liquid - flexible coupling are fully considered . The research contents of this paper mainly include the following aspects .

( 1 ) The dynamic equation of the coupling system of three - axis stable liquid - filled spacecraft is established by using the momentum moment theorem . The equivalent of the slosh liquid fuel is the second - order spring - mass model , and the composite controller based on the adaptive dynamic output feedback controller and the multi - modal feed - forward input shaping technology is designed aiming at the large - angle attitude maneuver problem of the liquid - filled spacecraft , and the numerical simulation results show that the controller is not dependent on the inertial parameter of the spacecraft , and has good robustness for external interference ;
The multi - modal ZVD input former has good restraining effect on the slosh of liquid fuel .

( 2 ) Under the typical underactuated system of some liquid - filled spacecraft coupling systems , an underactuated adaptive sliding mode controller is designed . A state observer based on the liquid slosh equation is designed by Lyapunov method . A state observer based on the liquid slosh equation is designed , which is used to estimate the first two - order slosh modes of the liquid slosh . Then , the input - forming feed - forward control technique is added to the control system to design the corresponding composite controller . The simulation results show that the adaptive sliding mode control method has good control accuracy and robustness to the parameter uncertainty .

Based on the Euler - Bernoulli beam theory , the dynamic equation of the flexible solar panel is established by using the Lagrange method , and the dynamic equation of the rigid spacecraft and the shaking liquid is established by using the Lagrange method . The simulation results show that the designed composite control strategy can meet the requirement of attitude control precision and effectively restrain the vibration of the flexible appendages and the liquid shake under consideration of the nonlinear saturation constraint .

( 4 ) The dynamics and control problems of coupling systems with large flexible structures are studied . It is assumed that the flexible appendages are nonlinear Euler - Bernoulli large deformation beam models , and the dynamic equations are established by Lagrange method . In view of the complexity of the control equation , the singular perturbation theory is introduced to decompose the control system into a slow - variable subsystem and a fast - variable subsystem . For the slow - variable subsystem , the hybrid control strategy of the thruster and the momentum wheel is designed to improve the control accuracy .
The Lyapunov control law of the piezoelectric intelligent element is applied to the fast changing system . The vibration of the flexible structure is effectively restrained in a short time . Numerical simulation results verify the effectiveness of the control strategy .

【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：V448.22

【参考文献】