多储液腔航天器刚液耦合动力学与复合控制

采用复合控制方法对充液航天器的姿态和轨道机动进行高精度控制.通过傅里叶-贝塞尔级数展开法,将低重力环境下液体的弯曲自由表面的动态边界条件转化为简单的微分方程,其中耦合液体晃动方程的状态向量由相对势函数的模态坐标和波高的模态坐标组成.通过广义准坐标下的拉格朗日方程得到航天器刚体部分运动和液体燃料晃动的耦合动力学方程,提出了自适应快速终端滑模策略和输入整形技术相结合的复合控制器,并分别用于控制携带有一个燃料腔和四个燃料腔航天器的轨道机动和姿态机动.通过数值模拟来验证控制器的效率和精度.结果表明,对于多储液腔航天器,如果在设计航天器的姿态和轨道控制器时没有充分考虑燃料晃动效应,那么在受控航天器系统中将会出现刚-液-控耦合问题并导致航天器姿态不稳定.而本研究中的复合自适应终端滑模控制器可以实现航天器机动的高精度控制并有效抑制液体燃料晃动.

RIGID AND LIQUID COUPLING DYNAMICS AND HYBRID CONTROL OF SPACECRAFT WITH MULTIPLE PROPELLANT TANKS

The compound control methods are widely used to control the orbit translation and attitude maneuver of liquid-filled spacecraft with high accuracy. The dynamic boundary conditions on curved liquid free surface under low-gravity environment are transformed to general simple differential equations by using Fourier-Bessel series expansion method and the state vectors of coupled liquid sloshing equations are composed by the modal coordinates of relative potential function and the modal coordinates of wave height. The coupled dynamic equations for the rigid platform motion and liquid fuel sloshing are obtained by means of Lagrange equations in terms of general quasi-coordinates. The expressions of the sloshing forces and moments are obtained by analyzing the liquid model. An adaptive fast terminal sliding mode controller and a composite controller that combines the adaptive fast terminal sliding mode strategy and the input shaping technology are respectively designed to control spacecraft orbit translation and attitude maneuver for two cases. In the first case, the spacecraft carries one partially liquid-filled propellant tank. In the second, the spacecraft carries four partially liquid-filled propellant tanks. The efficiency and the accuracy of the controllers are examined through numerical simulations. The results indicate that liquid-control-spacecraft coupled resonance can appear in the controlled spacecraft system if the sloshing effects have not been sufficiently taken accounted of during designing attitude and orbit controller for spacecraft with multiple propellant tanks, and this resonance will result in the instability of the spacecraft attitude. Nevertheless, such disadvantages have been efficiently inhibited by using presented composite adaptive terminal sliding mode controller.