Based on Hill guidance, the optimization of trajectories for the manned maneuvering unit rescuing an astronaut or equipment that becomes separated from a space station is studied because of minimum fuel, rendezvous accuracy, and time constraint requirements. The Hill guidance targeting errors induced by navigation error, target measurement error, and actuation error are analyzed. The minimum fuel solutions for 17 typical cases are found, and designing rules for the rescue trajectories are developed. A multi-impulse Hill guidance scheme is presented for simultaneously realizing accurate rendezvous and saving energy. Simulation results reveal that the multi-impulse scheme is much more superior to the conventional double-impulse Hill guidance scheme in rendezvous accuracy and consumes nearly the same amount of fuel as the later does.

We adopted optimal preview control methodology to design a terrain-following controller for a cruise missile. In this methodology, tracking errors and control increments are both considered in a quadratic penalty function. An augmented error system that involves future command inputs is built. Thus the preview control problem can be formulated as an optimal regulator problem. Integrating the general optimal servo system with preview feed-forward compensations that respectively feed forward future command inputs and future disturbances produces an optimal preview servo system. In the terrain-following system, the flight altitude of a cruise missile is the command input, and its future information can be known a priori. The wind is viewed as the disturbance in the system and is not previewable. Thus we designed a terrain-following controller with a basic state feedback and a feed-forward compensation for future altitude information. regarding the wind as a constant signal. Simulation results show that the performance of the terrain-following system with such an optimal preview controller is improved dramatically.

An optimal guidance law based on missile-target LOS angular rate is presented for intercepting a nonmaneuvering target. It is then integrated with sliding-mode control theory to derive an optimal sliding-mode guidance law for intercepting a maneuvering target. The new guidance method's robustness against target maneuvers and good miss distance performance are proved by the second method of Lyapunov and simulation results. The presented guidance law is simple to implement in practical applications

为了使导弹制导系统具备良好的鲁棒性，本文提出用滑模变结构控制理论设计末端导引规律。结合时变系统的特点，本文提出并应用了滑模自适应趋近律这一概念。理论分析和数字仿真表明自适应变结构制导律具有优良的弹道性能和鲁棒性。另外，此制导律比较简单，便于应用。