面向快速响应任务的卫星星下点轨迹调整轨道机动技术研究

In recent years, the operationally responsive space technology is an important research topic in international aerospace filed. Compared with rapid assembly and launch for new satellites, in-orbit satellite adjusting its ground track by orbit maneuver to accomplish the emergency Earth observation mission, is a more economical and efficient way. The traditional studies on the ground track adjustment are mainly for the fuel-optimal problem using coplanar maneuvers, but do not consider the requirement of response time. Based on the achieved analytical approximate results of the coplanar impulse maneuver, this project will study the orbit-maneuver optimization problem and the error analysis problem for ground track adjustment under noncoplanar impulse and constant thrust. In the condition of limited fuel, we will derive the reachable domain of the ground track under single orbital maneuver. Using the optimal control theory and the homotopic method, we will study the minimum-fuel and minimum-response-time ground track adjustment problems under impulse and constant thrust. Based on the results of single satellite and single ground target, we will study the mission planning problem for multiple satellites and multiple targets. Considering the navigation and control errors, we will study the error propagation mechanism for the ground track adjustment problem by using the linear and nonlinear covariance analysis methods, and then study the optimal correction maneuver. The research achievement of this project can provide theory and technology support for in-orbit satellites in Earth observation responsive missions.

近年来，快速响应空间技术是国际航天领域的重要研究方向。与新卫星快速组装发射相比，利用在轨卫星轨道机动调整其星下点轨迹，完成应急对地观测任务，是更为经济和快捷的方式。传统星下点轨迹调整的研究主要针对共面机动的燃料最优问题，而未考虑响应时间要求。本课题以军事和民用快速响应对地观测任务为背景，在目前取得的共面脉冲解析近似解基础上，继续研究异面脉冲和常值推力星下点轨迹调整的轨道机动优化问题和误差分析问题。考虑有限燃料条件下，研究单次轨道机动的星下点轨迹可达范围问题；利用最优控制理论和同伦法，研究脉冲和常值推力星下点轨迹调整的最小燃料和最小响应时间优化问题；在单星单目标点基础上，研究多星多目标点的星下点轨迹调整任务规划问题；考虑导航误差和控制误差，利用线性和非线性协方差分析方法，研究星下点轨迹调整问题的误差传播机理及修正控制策略。本项目的研究成果可为在轨卫星对地观测快速响应任务提供理论和技术支持。

快速响应任务要求短期内对局部的突发事件做出应急响应。当地震、森林火灾等自然灾害发生时，可利用在轨卫星轨道控制调整其星下点轨迹，在较短时间内实现对指定目标的过顶成像。本项目以空间快速响应为背景，研究了星下点轨迹调整问题的可达范围、时间最优、燃料最优等轨道控制问题。针对星下点轨迹调整可达范围问题，推导了脉冲控制与轨道参数变化的二阶高斯变分方程，并基于此求解了考虑J2摄动单脉冲下给定轨道星下点轨迹的可达范围问题。针对时间最优问题，推导了最小响应时间的解析近似；针对多目标问题，研究了J2摄动模型下单次共面脉冲飞越多个地面目标的星下点轨迹调整问题，并给出了单目标和双脉冲情况下的最小燃料解。针对不确定性问题，考虑导航和控制误差，基于线性协方差方法，求解了脉冲机动控制不确定情况下的最小终端状态误差问题。基于星下点轨迹研究成果，设计了大椭圆木星回归轨道，并用于木星磁场探测问题，获得了第十届全国空间轨道设计竞赛冠军。本项目的研究成果可为在轨卫星对地观测快速响应任务提供理论和技术支持。