控制力矩陀螺磁轴承-框架动力学耦合特性仿真研究简

框架角速率精度决定着控制力矩陀螺输出的姿态控制力矩精度,前者的精度由框架伺服电机力矩精度和框架转动惯量决定.磁悬浮控制力矩陀螺框架转动和陀螺转子的微小扭摆运动间存在动力学耦合,其框架表现出比标称值大的等效转动惯量.在柔性结构框架动力学模型和磁轴承刚度-阻尼模型基础上,研究磁轴承-框架动力学特性,推导出框架等效转动惯量和磁轴承控制参数之间的关系式,表明调整磁轴承控制参数能增大框架等效转动惯量,提高框架角速率精度.根据闭环系统稳定性和轴承承载力,确定了磁轴承控制参数取值范围,并给出了框架等效转动惯量的调节范围.通过对某小型磁悬浮控制力矩陀螺框架角速率控制系统的Simulink仿真,证明了控制力矩精度可以提高5倍,验证了模型的准确性.

Simulation Study on Dynamic Coupling Characteristics between the Gimbals and Magnetic Bearings of CMG

The accuracy of gimbal-rate determines the precision of the output attitude control torque of a control moment gyroscope （CMG）. The former is determined by the torque precision of the gimhal servo motor together with the moment of inertia of the gimbals. Because of the dynamic coupling between the gimbal rotation and the rotor radial rotation of the magnetic bearing, magnetically sus- pended CMG demonstrates larger apparent gimbal inertia than its mechanical inertia, thus achieve higher gimbal rate accuracy and high pointing precision. Based on the gimbal control-loop dynamics with compliant structures and the stiffness-damping model of the magnetic bearing （MB） control- loop, the gimbal-MB coupling model was built. The relationship between the equivalent gimbal iner- tia and the MB＇s control parameters and the adjustable range of the gimbal inertia was preserited. Simulation results on a small MSCMG gimbal control-loop showed that the relationship presented was accurate and the output torque precision could be improved by 5 times.