方位角约束自主交会变结构制导律设计

针对空间交会视线相对运动动力学模型具有时变非线性和参数不确定性的特点,提出了一种基于非线性滑动模态的自主交会变结构制导算法。通过将视线运动模型划分为横向和纵向运动模型,分别设计了相应的非线性滑动模态。横向滑动模态是一种由视线角速率、视线角和时间构成的非线性函数,而纵向滑动模态则是由距离、速率以及时间构成的非线性函数。然后,根据Lyapunov稳定性理论分别推导了横向和纵向自主交会变结构制导规律。横向制导实现了带有末端方位角约束的自主接近;纵向制导保证了软交会所要求的距离和速度协同控制。仿真结果表明,设计的方法在只使用相对信息量的前提下克服了交会模型的耦合非线性和参数不确定性,并能适用于不同高度圆轨道和椭圆轨道上的V-bar和R-bar自主交会任务。

Variable Structure Guidance for Autonomous Rendezvous with Aspect Constraint

A variable structure guidance for autonomous rendezvous is proposed based on a line-of-sight(LOS) relative dynamics model with time-varying nonlinearity and parameter uncertainty.The LOS model is classified as a lateral model and a longitudinal model so that the corresponding guidance laws can be designed respectively.The designed lateral sliding model is a nonlinear function about LOS angle,LOS angle rate and time while the longitudinal nonlinear sliding model consists of range,range-rate and time.Then the rendezvous guidance laws are derived based on the nonlinear sliding model control and Lyapunov stability theory.The proximity with aspect constraint is achieved by the lateral guidance while the range and velocity requirements are satisfied with the longitudinal guidance.Numerical simulation shows that the time-varying nonlinearity and model uncertainty can be overcame with the present guidance strategy using the autonomous navigation information only.Moreover,both R-bar and V-bar autonomous rendezvous missions in any keplerian orbit can be completed with this guidance strategy.