再入制导和弹道跟踪误差分析

新一代可重复使用运载器对再入制导提出了更高地要求。目前的空间运输系统证明基于阻力加速度的制导方法是行之有效的。其基本概念是跟踪基准阻力加速度包线，在飞行过程中可根据需要更新这个包线。跟踪适当的阻力加速度包线保证了飞行器可以飞行准确的距离达到目标，同时满足弹道约束。在横向上，我们可采用类似于美国航天飞机的倾斜反转逻辑或航向角跟踪技术。本文推导出了基于反馈线性化的控制算法，并将其应用于可重复使用运载器纵向和横向的制导。最后，我们分析了阻力加速度跟踪的误差。

Entry guidance and trajectory tracking error analysis

The new generation of Reusable Launch Vehicles (RLVs) demands improvements to the current entry guidance capability.The acceleration guidance method has proven effective for the current space transportation system.The basic concept is to track a reference drag acceleration generated by a planner,replanning these profiles periodically if necessary.From the guidance perspective,the trajectory is controlled by adjusting the normal and lateral components of lift to bend the trajectory in the vertical and lateral directions respectively.Tracking an appropriately designed drag profile ensures that the vehicle will fly the correct distance to reach the target without ever violating the vehicle constraints.In the lateral direction,either shuttle type of bank reversal logic or heading angle tracking can be used to ensure that the trajectory will curve such that the desired target is reached.In this paper,we first derive a feedback linearization based control algorithm.We then formulate a baseline entry tracking law for the RLVs.Finally the drag tracking error is analyzed.