一种超静卫星动力学建模及控制方法

Dynamics Modeling and Control for Ultra-Quiet Satellite

针对Stewart超静卫星载荷和星体平台在姿态控制时存在平动和转动耦合问题,提出一种基于广义动量定理,反映载荷质心相对整星质心平动和转动耦合因素的动力学建模方法。由于载荷质心存在平动位移,极易造成Stewart平台支杆行程饱和,甚至发生碰撞。为避免支杆行程饱和,设计了具有平动前馈补偿控制的载荷控制器和具有支杆去饱和控制的星体平台控制器。通过3种姿态控制模式验证了控制器的正确性。仿真结果表明,在星体平台姿态实现10″控制精度的基础上,通过Stewart平台高精度指向控制,实现载荷0.1″指向控制。星体平台和载荷控制器在3种姿态控制模式下都能够有效实现支杆去饱和控制,避免发生机械碰撞。

To describe the coupling factor of translation and rotation actually,dynamics modeling based on generalized momentum is presented for Stewart ultra-quiet satellite. The coupling factor between centroid of payload and spacecraft is exactly analyzed in the dynamics model. Due to the translation of payload centroid,the lengths of Stewart struts are easily saturable,even collision occurred. To deal with this problem,the payload controller with translation compensation and base controller with struts desaturation are designed. They are validated by three attitude control modes. Simulation results show that the payload pointing accuracy is up to 0. 1″,while the base attitude control accuracy is 10″. The struts desaturation performance of payload controller and base controller come true in three attitude control modes.