不平衡飞轮的扰动特性

Study on Disturbance Characteristics of Imbalance Flywheels

高精度航天器对指向精度有极高的要求,飞轮是卫星姿态控制环节中不可或缺的执行部件,在研制和装备过程中,不可避免地具有微量的偏心或动不平衡,在姿态机动和稳定控制的过程中,飞轮的旋转会产生干扰力。将动静不平衡质量作为航天器的一部分,推导出完整航天器动力学姿态方程,进行动力学仿真,并根据完整的姿态动力学方程简化分析仿真结果。研究发现动静不平衡质量在飞轮高速转动时,对姿态均有影响,动不平衡质量对姿态的影响与安装位置关系很小,而静不平衡质量呈现线性关系,且两者对姿态的影响满足线性叠加。单轴转动时,指向精度的长周期变化只与飞轮的固有特性有关,与转速的大小无关。多轴转动时,姿态会振荡或发散,与初始相位有关;但对姿态的影响不满足单轴转动的叠加。

High-precision spacecraft has very serious demands on pointing accuracy. The flywheel is an integral part of the execution units for satellite attitude control. In the research and development process, small eccentricity or dynamic imbalance is unavoidable. So, in the attitude maneuver and stability control process, rotation of the flywheel can cause interference forces. In this paper, taking the imbalance mass as a part of the spacecraft, the spacecraft attitude dynamic equations are conducted and the simulation is carried out. The simulation results are analyzed and illustrated. It is found that when the flywheel is rotating at high speed, the attitude of the spacecraft is essentially independent of the dynamic unbalance mass and its installation location, while it is linearly related to the static unbalance mass. When a single flywheel rotates, the long-period pointing accuracy depends on the inherent characteristics of the flywheel only, instead of its rotating speed. While multi-flywheels rotate, the attitude will oscillate or diverge, depending on the initial phase. Furthermore, effect of the multi-flywheels rotating does not mean the superposition of the influences of single-flywheel’s rotating.