一种带航迹角约束的临近空间目标拦截中制导算法

针对采用双脉冲发动机的防空导弹拦截临近空间高速目标的多约束中制导问题,设计了一种基于逆轨拦截且满足过载收敛的预测-校正制导方法。该算法在基于由最优控制理论推导的满足终端位置、速度约束的ZEM-ZEV算法基础上,以具有航迹角约束的零控拦截流形作为交班条件,采用数值预测方法对剩余飞行时间进行高精度求解,通过在线动态生成初-中制导交班的速度方向和II脉冲发动机的开机时刻来降低中制导段需用过载。蒙特卡洛打靶仿真结果表明本文所提出的中制导算法能够满足带航迹角约束的零控拦截条件,对模型的参数偏差和不确定性具有强鲁棒性,具备重要的理论意义和工程应用价值。     

Relative motion guidance for near-rectilinear lunar orbits with path constraints via actor-critic reinforcement learning

This paper presents a feedback guidance algorithm for proximity operation in cislunar environment based on actor-critic reinforcement learning. The algorithm is lightweight, closed-loop, and capable of taking path constraints into account. The method relies on reinforcement learning to make the well known Zero-Effort-Miss/Zero-Effort-Velocity guidance state dependent and allow for path constraints to be directly embedded. The algorithm is tested in the circular restricted three-body problem (CRTBP) framework for Near Rectilinear Orbits (NRO) in the Earth-Moon system. It shows promising results in terminal guidance error and satisfies path constraints in constraint scenarios comprising spherical constraints and keep-out-spheres with approach corridors. Furthermore, this approach indicates that reinforcement learning can be effectively used to solve constrained relative spacecraft guidance problems in complex environments and thus can be effective for autonomous relative motion operations in the Earth-Moon dynamical environment.     

Reducing mission operations costs through spacecraft autonomy: the near earth asteroid rendezvous (near) experience

With a maximum time of 12 days out of ground contact and a round-trip light time as high as 56 minutes, The Near Earth Asteroid Rendezvous (NEAR) spacecraft requires a moderate degree of onboard autonomy to react to faults and safe the spacecraft. Beyond the basic safing requirements, additional functions are carried out onboard. For example, on-board calculation of the Sun, Earth, asteroid, and spacecraft positions allow the spacecraft to autonomously orient itself for science and downlink operations. On-board autonomous momentum management during cruise relieves Mission Operations from planning, scheduling, and carrying out many manual momentum dumps. During development, additional operations, such as center-of-mass management during propulsive maneuvers and optical navigation were also considered for onboard autonomy on the NEAR spacecraft, but were not selected. The allocation of functions to onboard software or to ground operations involved tradeoffs such as development time for onboard software versus ground software, resource management, life cycle costs, and spacecraft safety.After two years of cruise operations, considerable experience with the NEAR autonomy system has accrued. The utility of some autonomous capabilities is greater than expected, others less so. Software uploads increased spacecraft autonomy in some cases, and the impact on Mission Operations can be assessed. Allocation of functions between spacecraft autonomy and ground operation during development of future missions can be improved by applying the lessons learned from the NEAR experience.     

Design and analysis of a direct transfer trajectory from a near rectilinear halo orbit to a low lunar orbit

A near rectilinear halo orbit (NRHO) is regarded as a potential orbit for a future deep space station that can effectively support sustainable crewed lunar exploration missions. In this paper, the L₂ southern NRHOs are selected as the research object, and a direct transfer trajectory from an NRHO to a low lunar orbit (LLO) is designed and analyzed. First, based on the circular restricted three-body problem, the characteristics of NRHOs are discussed including geometric behaviour, stability and synodic resonance. Second, optimal direct transfer trajectories are obtained by combining a local gradient optimization with a numerical continuation strategy. A reachable domain calculation model is established. Finally, simulations are carried out to verify the feasibility of the trajectory design method. The relationship between the velocity change and the reachable domain is further analysed through simulation calculations.     

基于边缘电流法近远场变换中的探头补偿

针对目前平面近远场变换中，探头H面方向图对天线远区副瓣引入误差较大的情况，研究了一种基于边缘电流法近远场变换的探头补偿。通过在微波暗室对某频段阵列天线测量，并分别用传统使用的stratton-chu积分法、E面电场法与边缘电流法进行近远场变换并进行比较。结果表明，此方法相比传统方法，副瓣精度基本接近国际先进水平，远远高于国内现有水平，证明了该方法的有效性和工程实用性，并填补了国内空白。     

近区场强仪自动校准测试的研究

介绍了近区场强仪的校准原理和方法，着重介绍了近区场强仪的自动校准测试系统和软件的研究。     

Near space as a sui generis zone: A tri-layer approach of delimitation

The lack of a legal boundary between air space and outer space has not given rise to significant difficulties in the determination of applicable law with respect to traditional flight craft – aircraft and space objects, due to their separated sphere of activities. But the advent of new flight craft that are capable of operating in the intermediate “near space”, i.e. Near Space Vehicles, would render a clarification of their applicable law and the legal status of the zone requisite. For the purpose of balancing the right of exploration and use of near space and the security interest of subjacent States, this short note proposes a tri-layer approach of delimitation by which near space is established as a sui generis zone reserved exclusively for peaceful purposes, while the space below the upper operative limit of aircraft and that above the lower operative limit of space craft are air space and outer space respectively.     

可组装轻质空间结构技术研究进展

概述了当前可组装轻质空间结构的构建技术方法,具体包含嵌锁组装、堆叠组装、折叠成型、充气成型和张拉整体成型五种主流技术;以太空建造、月面栖息地和近空间飞行器为典型应用,介绍了现有可组装轻质空间结构技术的航空航天应用。最后,对比分析了各空间结构技术,讨论了现有挑战和技术难点,并对其未来发展方向进行了展望,旨在为今后航空航天任务中所需的轻量化空间结构研究提供参考。     

临近空间高超声速飞行器关键技术及展望

随着各国对提高军队通信、反应和作战能力的需求与日俱增,发展临近空间高超声速 飞行器技术的重要性愈发明显。综述了临近空间高超声速飞行器国内外的发展现状与趋 势,系统全面地分析了发展临近空间高超声速飞行器的关键技术,包括总体设计技术、气动 力和气动热技术、高温长时间热防护技术、高精度GNC技术、有效载荷抛撒技术以及发动机 技术。在此基础上,最后提出了适合我国国情的临近空间高超声速飞行器技术的发展设想。
     

基于组合优化算法的临近空间飞行器轨迹优化

提出一种临近空间飞行器轨迹优化方法,利用基于支持向量机与遗传算法的组合优化算法,解决多约束条件下的高效轨迹优化问题。首先,建立临近空间飞行器轨迹优化数学模型。然后,通过参数化方法和惩罚函数法将轨迹优化问题转化为约束参数优化问题。在此基础上,提出一种求解无约束参数优化问题的组合优化算法,通过支持向量机对遗传过程中产生的种群进行分类,提高基本遗传算法的计算效率,结合轨迹优化数学模型,给出轨迹优化算法。最后,以临近空间飞行器航程最远轨迹优化问题为例,进行数学仿真分析。仿真结果表明,针对给定的算例,文中提出的方法与基于基本遗传算法的轨迹优化方法相比,计算效率显著提高。