简介：为了提高标准Cubature卡尔曼滤波（CKF）的稳定性和鲁棒性，提出一种改进的多重渐消H∞滤波cubamre卡尔曼滤波算法。首先基于系统状态的可观测性给出多重渐消因子矩阵求解过程，提高滤波算法的稳定性，抑制滤波发散；其次，引入H∞鲁棒思想，构造多重渐消H∞滤波Cubature卡尔曼滤波器；最后，提出采用一种奇异值分解的矩阵分解策略代替标准Cubature卡尔曼滤波中的Cholesky分解，进一步提高算法的数值稳定性。实际GPS／INS组合导航实验表明，改进的多重渐消H∞滤波Cubature卡尔曼滤波算法不仅能有效抑制滤波发散提高算法的稳定性，而且对观测野值具有更高的鲁棒性；提出的新算法与标准CKF算法相比，XYZ三个方向的位置精度分别提高了55．8％，46．6％和39．7％。

简介：DrivenbycuriosityaboutpossibleflightoptionsfortheChang’e-2spacecraftafteritremainsattheSun-EarthL2point,effectiveapproachesweredevelopedfordesigningpreliminaryfuel-optimalnear-Earthasteroidflybytrajectories.Theapproachesincludetheuseofmodifiedunstablemanifolds,gridsearchofthemanifolds’parameters,andatwo-impulsemaneuverfororbitalphasematchingandz-axisbiaschange,andaredemonstratedtobeeffectiveinasteroidtargetscreeningandtrajectoryoptimization.Asteroidflybysareexpectedtobewithinadistanceof2×107kmfromtheEarthowingtotheconstrainedEarth-spacecraftcommunicationrange.Inthiscase,thespacecraft’sorbitalmotionissignificantlyaffectedbythegravitiesofboththeSunandtheEarth,andtherefore,theconceptofthe"heliocentricoscillating-Keplerorbit"isproposed,becausetheclassicalorbitalelementsoftheflybytrajectoriesreferencedintheheliocentricinertialframeoscillatesignificantlywithrespecttotime.Theanalysisandresultspresentedinthisstudyshowthat,amongtheasteroidswhoseorbitsarethemostaccuratelypredicted,"Toutatis","2005NZ6",or"2010CL19"mightbeencounteredbyChang’e-2inlate2012or2013withtotalimpulseslessthan100m/s.