应用非线性模型预测控制的绳系卫星Halo轨道保持控制

Station-keeping of Tethered Satellite System Around a Halo Orbit Using Nonlinear Model Predictive Control

针对哑铃型绳系卫星在圆形限制性三体问题(CRTBP)中的Halo轨道保持控制问题,应用非线性模型预测控制(NMPC)方法设计了Halo轨道保持控制器。首先采用摄动法得到目标Halo轨道,通过跟踪目标轨道上一运动点,将其转化为目标跟踪控制问题,然后设计非线性模型预测控制器对其进行跟踪控制。利用4阶Ronge-Kutta法对原非线性模型进行离散化,将预测控制中的有限时域最优问题转化为非线性规划问题进行求解,得到下一周期的控制量。最后通过数值仿真验证了即使在初始位置偏差较大的情况下,所设计的控制器只需要很少的速度增量就可使绳系卫星系统运动至目标轨道,并精确地保持在目标轨道上。

The nonlinear model predictive control（NMPC）method is employed to design the controller for the station-keeping mission around Halo orbits of dumbbell tethered satellites in the circular restricted three-body problem（CRTBP）.First,the target Halo orbit is obtained using the perturbation method.The station-keeping control problem is translated into a tracking control problem by tracking a target point moving along the reference orbit.Then,the original system model is discretized by the fourth-order Ronge-Kutta method.The finite horizon optimal control problem is transformed into a nonlinear optimization problem and solved by nonlinear programming,which then provides the control input for the next control period.Finally,the numerical simulation results demonstrate that even in the case of large initial position deviation,the controller can still guarantee that the tethered satellite system move along the target orbit precisely with relatively small velocity increment.