三轴气浮台挠性航天器动力学模拟方法研究

本文研究利用气浮台上的动量轮执行机构,模拟卫星上挠性附件振动产生的干扰力矩的卫星物理仿真实验方法,以克服三轴气浮台不能直接安装挠性附件进行仿真的局限性.本实验方法通过设计一个跟踪控制器,令气浮台的姿态角速度跟踪挠性卫星参考动力学,并由动量轮产生控制力矩,该力矩即是实验模拟的挠性振动干扰力矩.理论和仿真研究表明:(1)本文提出的挠性干扰力矩模拟方法可以较好地模拟低阶挠性振动干扰力矩;(2)理论上当控制器的增益参数越大,系统能够模拟的干扰力矩频率就越大,但是由于测量噪声的影响,反馈增益不能选得过大;(3)本方法模拟的干扰力矩与真实干扰力矩存在一定的相位延迟,这是由于控制器和执行机构的固有延迟造成的.通过引入超前-滞后校正网络可以有效减小延迟的影响.

Method for Flexible Satellite Dynamics Simulation on Three-Axis Air-Bearing Table

Because of the Earth gravity, flexible appendages cannot be fixed on the table, three-axis air-bearing table cannot be used to simulate attitude dynamics of a flexible satellite, a method is developed by using momentum wheels to simulate the vibrational disturbance torque of satellite flexible appendages on three-axis air-bearing table. By designing a tracking controller, the air-bearing table' s angular velocity is used to track reference dynamics of the flexible satellite, the momentum wheel provide the control torque, i.e. the vibration disturbance torque to be simulated. The theory and mathematial simulations show: ( 1 ) This method can simulate low-order flexible vibration disturbance torque well; (2) In theory, the greater the controller gain, the higher frequency of disturbance torque can be simulated. However, because of measurement noise, the feedback gain cannot be too great; (3) Due to the inherent de]ay of controller and actuator, there is phase delay between the emulational disturbance torque and real disturbance torque. Therefore, a lead-lag correction network is introduced to reduce the effect of phase delay.