末端带集中质量的可伸展挠性附件与航天器姿态耦合动力学分析

ATTITUDE DYNAMICS OF A SPACECRAFT WITH TIP MASS ATTACHED DEPLOYING FLEXIBLE APPENDAGE

结构复杂的航天器带有几十米、上百米大型挠性附件,附件末端还带有大质量刚体。大型挠性附件在空中展开时,其伸展运动、弹性振动和航天器的姿态运动相互耦合。为研究附件伸展和振动对航天器姿态的影响并设计有效的控制器,有必要建立可伸缩挠性附件与航天器姿态耦合动力学模型。为此,利用动量矩定理推导出末端带集中质量的可伸缩柔性附件与航天器姿态耦合动力学方程,研究了带末端质量附件的伸展运动对航天器姿态及对附件挠性振动的影响。附件匀速伸展,用Runge-Kutta法对系统进行数学仿真,仿真结果表明:伸展过程姿态角误差增大,附件振幅增大,附件频率不断降低,并且末端质量越大时,在相同长度处附件频率越小,增加了控制的难度。对末端带集中质量的挠性附件和中心刚体进行主动控制能有效抑制挠性附件的振动,满足姿态角精度要求。

The coupled dynamic equations of a spacecraft with tip mass attached flexible appendage which is deployable are obtained by using the momentum theorem. The attitude dynamics of the spacecraft and the vibrations of the appendage under the influence of appendage extending with tip mass are investigated. Based on the dynamic equations, and by using Runge-Kutta method, the numerical results of the appendage motion during uniform velocity deployment are obtained. The results show that during deployment, the attitude deviation and the amplitudes of vibration both increase while the frequencies of appendage vibration decrease and as the tip mass becomes larger the frequencies become lower under the same length of appendage and it is more difficult to control the system. The results also show that adaptive control of the appendage and center rigid body can suppress the vibration effectively and satisfies the precision requirement of attitude anagles.