Optimization of multi-revolution low-thrust transfer based on modified direct method

A modified direct optimization method is proposed to solve the optimal multi-revolution transfer with low-thrust between Earth-orbits. First, through parameterizing the control steering angles by costate variables, the search space of free parameters has been decreased. Then, in order to obtain the global optimal solution effectively and robustly, the simulated annealing and penalty function strategies were used to handle the constraints, and a GA/SQP hybrid optimization algorithm was utilized to solve the parameter optimization problem, in which, a feasible suboptimal solution obtained by GA was submitted as an initial parameter set to SQP for refinement. Comparing to the classical direct method, this novel method has fewer free parameters, needs not initial guesses, and has higher computation precision. An optimal-fuel transfer problem from LEO to GEO was taken as an example to validate the proposed approach. The results of simulation indicate that our approach is available to solve the problem of optimal muhi-revolution transfer between Earth-orbits.     

Autonomous determination of orbit for probe around asteroids using unscented Kalman filter

The observed images of the asteroid and the asteroid reference images are used to obtain the probe-to-asteroid direction and the location of the limb features of the asteroid in the inertial coordinate. These information in combination with the shape model of the asteroid and, attitude information of the probe are utilized to obtain the position of the probe. The position information is then input to the UKF which determines the real-time orbit of the probe. Finally, the autonomous orbit determination algorithm is validated using digital simulation. The determination of orbit Using UKF is compared with that using extended Kalman filter (EKF), and the result shows that UKF is superior to EKF.     

Design of MGA trajectories for main belt asteroid

0　INTRODUCTIONAsteroidsareofkeenscientificinterest ,holdingcluestotheformationandevolutionofoursolarsystem .Currentplansforplanetaryandsolarsystemexplorationcallforinnovative ,excitingmissions ,whicharelowcost.Missiontoasteroidswithlowlaunchenergiesandshortflighttimescanfulfillallofthesegoals .Ifthetrajectoryiswell designed ,asinglemissioncanachieveseveralscien tificobjectives .Inviewofthepastresearchesinthisfield ,BreakwellandPerkodemonstratedthatthe‘patched conic’theoryisreasonablya…     

Timeline based autonomous mission planning system for deep space exploration

In order to realize the explorer autonomy, the software architecture of autonomous mission management system (AMMS) is given for the deep space explorer, and the autonomous mission planning system, the kernel part of this architecture, is designed in detail. In order to describe the parallel activity, the state timeline is introduced to build the formal model of the planning system and based on this model, the temporal constraint satisfaction planning algorithm is proposed to produce the explorer‘ s activity sequence. With some key subsystems of the deep space explorer as examples, the autonomous mission planning simulation system is designed.The results show that this system can calculate the executable activity sequence with the given mission goals and initial state of the explorer.     

利用混合法进行地球-火星小推力轨道设计

研究固定推力幅值情况下燃料最省小推力轨道转移问题.利用混合法,即通过结合Pontryagin极小值原理和序列二次规划方法,舍弃了横截条件,避免了直接求解非线性两点边值问题,从而极大地提高了迭代的收敛性.以定常推力幅值地球-火星燃料最省小推力转移为例给出了混合法完整的计算步骤,仿真结果表明采用混合法收敛速度快,得到的状态和共轭状态轨线连续光滑,验证了混合法在设计行星际小推力转移轨道中的有效性.     

基于标称轨道的小推力轨道设计方法

研究了推力可变情况下燃料最省小推力轨道转移问题。分析了传统轨道优化模型在数值求解过程中存在的困难,通过引入标称轨道的概念,提出了一种新的轨道优化模型———标称轨道优化模型。新的轨道优化模型克服了传统轨道优化模型在数值求解中存在的困难,并具有收敛速度快、初始猜测容易的优点。以飞行器从地球向火星的小推力转移为例,验证了标称轨道优化模型的正确性。最后给出了标称轨道优化模型的主要用途及适用范围。     

论工程在科技及经济社会发展中的创新驱动作用

从工程与科学技术辩证关系的角度,在四个方面讨论了工程在创新驱动发展中的作用和意义.从劳动与劳动工具对人类进化和发展过程中的关键作用入手,讨论了工程的本质以及科学、技术、工程三者的关系,认为三者处于“无首尾逻辑”的不断循环的融合体状态,三者互相依赖、互相推动,而工程直接联系着技术的应用和科学的基础,在这一循环中起着“扳机”和载体的作用.以中国航天经历仿制阶段、自主研制阶段、跟踪发展阶段以及开始步入创新驱动发展新时期的58 年发展历程为例,论述了以重大工程带动科技发展对我国来说是一条成功之路.提出在未来的创新驱动发展中要坚持两项原则：一是坚持通过重大工程带动科技发展和社会进步;二是要将基础科研按其本身的特点并吸纳重大工程的成功经验制定发展规划.讨论了工程成果对于科学发展的基础作用,提出工程成果不仅是现代基础科学取得重大突破的必要手段和基础,还牵引着诸多基础学科的生成,完善和推动基础学科的发展;工程设施所提供的成果,既是设计成果、验证结果,也是运营的伴行装置;既是对象的物理表现,也是模型化认识的基础科学.对工程师的使命强调了三点认识：一是要依据系统工程的原则、方法和程序指导工程实践,一项重大工程系统在其运行中,必然要包括“非拥护性评审”以及相应的机会成本权衡;二是系统工程实施的第一步是工程需求论证,而复杂工程系统的需求论证必须是全域性的,涉及技术、经济、社会的诸多方面,否则可能造成巨大的损失;三是科技进步将人类社会推到高科技时代的同时,也把我们带进了为科技进步和工程建设而付出的各种代价之中,工程师要与科学家携手,通过“科学一技术一工程”无首尾逻辑的综合运用,共同解决当代民生难点课题,这是工程师的?     

中国的探月工程——中国航天第三个里程碑

人类对月球的探测显示了人类的智慧和能力,也带动了人类社会及科学技术的进步和发展。中国以“绕”、“落”、“回”为标志的探月工程是中国航天的第三个里程碑性工程,既是国力强大的体现,也是中国航天能力的表征。