绳系卫星实施安全捕获的能量最优控制

Energy-optimal Control of Safe Capture by Using Tethered Subsatellite

考虑系绳质量、系统质心变化及状态、控制约束,基于Lagrange方程给出了圆轨道条件下空间绳系网捕系统三维动力学模型。推导得到了零相对速度条件下的安全捕获末端条件,研究了面内安全捕获策略下的非线性能量最优控制问题。为保证方法的适用性,基于Legendre伪谱法将连续时间最优控制问题离散为标准的非线性动态规划问题。最后在考虑捕获控制前初始面外角偏差分别为5°和15°的情况下,通过数值仿真验证了该方法的有效性。

The 3D dynamics model of the tethered subsatellite in circular orbit is presented for the rendez- vous and capture of payloads on the basis of Lagrange equations, which also takes tether mass, centroid drift and mission-related state-controlled constrains into consideration. The end terms of zero velocity rendez- vous are derived for the study of nonlinear energy-optimal control of safe capture. For ensuring the adapta- bility, the optimal control is solved by discretizing the problem based on the Legendre pseudospectral meth- od. The initial error of the out-of-plane libration angle before capture control is considered as 5 or 15 degree and the numerical results well demonstrate the performance of the proposed strategy.