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New celestial assisted INS initial alignment method for lunar explorer

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Journal of Systems Engineering and Electronics 2013年第1期24卷 108-117页

作者： weiren wu Xiaolin Ning Lingling Liu Lunar Exploration and Aerospace Engineering Center School of Instrument Science and Opto-electronics Engineering Beihang University Science and Technology on Inertial Laboratory Fundamental Science on Novel Inertial Instrument and Navigation System Technology Laboratory

In the future lunar exploration programs of China, soft landing, sampling and returning will be realized. For lunar explorers such as Rovers, Landers and Ascenders, the inertial navigation system （INS） will be used to obtain high-precision navigation information. INS propagates position, velocity and attitude by integration of sensed accelerations, so initial alignment is needed before INS can work properly. However, traditional ground-based initial alignment methods cannot work well on the lunar surface because of its low rotation rate （0.55°/h）. For solving this problem, a new autonomous INS initial alignment method assisted by celestial observations is proposed, which uses star observations to help INS estimate its attitude, gyroscopes drifts and accelerometer biases. Simulations show that this new method can not only speed up alignment, but also improve the alignment accuracy. Furthermore, the impact factors such as initial conditions, accuracy of INS sensors, and accuracy of star sensor on alignment accuracy are analyzed in details, which provide guidance for the engineering applications of this method. This method could be a promising and attractive solution for lunar explorer＇s initial alignment.

关键词： lunar exploration initial alignment inertial navigation,celestial navigation.

Methods for mapping QTLs underlying endosperm traits based on random hybridization design

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Chinese Science Bulletin 2006年第16期51卷 1976-1981页

作者： WEN Yongxian wu weiren College of Crop Science Fujian Agriculture & Forestry UniversityFuzhou 350002 China

Several methods of interval mapping of QTLs underlying endosperm traits based on random hybridization designs and the triploid genetic model are proposed. The basic idea is: plants (or lines) from a population with known marker genotype information are randomly hybridized to generate a population of hybrid lines for endosperm QTL mapping; a mixture of seeds of each hybrid line is measured for the en- dosperm trait to get the mean of the line; then en- dosperm QTL mapping and effect estimation is per- formed using the endosperm trait means of hybrid lines and the marker genotype information of parental plants (or lines). The feasibility and efficiency of the methods are examined by computer simulations. Results show that the methods can precisely map endosperm QTLs and unbiasedly and efficiently es- timate the three effects (additive effect, first dominant effect, second dominant effect) of endosperm QTLs.

关键词：胚乳 QTLs 随机杂化设计遗传模型

Design of communication relay mission for supporting lunar-farside soft landing

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Science China(Information Sciences) 2018年第4期61卷 73-86页

作者： weiren wu Yuhua TANG Lihua ZHANG Dong QIAO Lunar Exploration Program and Space Engineering Center School of Aerospace Engineering Beijing Institute of Technology Dong Fang Hong Satellite Co.Ltd. Key Laboratory of Autonomous Navigation and Control for Deep Space Exploration Ministry of Industry and Information Technology

Chang’E-IV will be the first soft-landing and rover mission on the lunar farside. The relay satellite, which is located near the Earth-Moon L2 point for relay communication, is the key to the landing mission. Based on an analysis of the characteristics of the task and the technical difficulties associated with the relay satellite system, the overall design scheme of the relay communication mission is proposed in terms of trajectory design and communication system design among other aspects. First, according to the complex dynamic environment, a mission orbit that serves as an uninterrupted communication link is presented. A short-duration and low-energy transfer trajectory with lunar flyby is discussed. Orbital correction and a low-cost control strategy for orbit maintenance in the Earth-Moon L2 point region are provided. Second,considering the existing technical constraints, the requirement of relay communication in different stages and the design schemes of frequency division and redundant relay communication system are introduced. Finally,based on the trajectory design index and the performance of the communication system, the overall design scheme of the relay communication mission is proposed. This mission will provide the technical support and reference required for the Chang’E-IV mission.

关键词： lunar farside soft landing relay communication Earth-Moon Lagrange point

Effect of orbital shadow at an Earth-Moon Lagrange point on relay communication mission

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Science China(Information Sciences) 2017年第11期60卷 211-220页

作者： Yuhua TANG weiren wu Dong QIAO Xiangyu LI School of Aerospace Engineering Beijing Institute of Technology

The shadow effect is an important constraint to be considered during the implementation of exploration missions. In this paper, for the Earth-Moon Lagrange point L2 relay communication mission, shadow effect issues on a periodic orbit about L2 are investigated. A systematic analysis based on the time domain and phase space is performed including the distribution, duration, and frequency of shadows. First, the LindstedtPoincare and second-order differential correction methods are used in conjunction with the DE421 planetary ephemeris to achieve a mission trajectory family in a high-precision ephemeris model. Next, on the basis of a conical shadow model, the influence of different orbital phases and amplitudes on the shadow is analyzed. The distribution of the shadow is investigated as well. Finally, the configuration of the shadow and its characteristics are studied. This study provides an important reference and basis for mission orbit design and shadow avoidance for relay satellites at an Earth-Moon Lagrange point.

关键词： Earth-Moon system equilibrium point relay orbit shadow effect motion control

Modern quantitative genetics:Dissecting complex polygenic systems into individual genetic factors

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Chinese Science Bulletin 2012年第21期57卷 2635-2636页

作者： wu weiren College of Life Sciences Fujian Agriculture and Forestry University Fuzhou 350002 China

Modern quantitative genetics began in the late 1980s with the advent and application of molecular marker *** markers made it possible to genotype the entire genome of an ***,for the first time,quantitative genetic analysis could be performed based on phenotypic and genotypic *** a result,quantitative genetic studies were no longer limited to the estimation of genetic parameters by treating the polygenic system as a whole,but were able to identify the locations and effects of individual quantitative trait loci (QTLs) as well as to examine the interactions between QTLs.

关键词：数量遗传学基因组学遗传因素个体系统分子标记技术解剖数量遗传分析

Strategy for the mapping of interactive genes using bulked segregant analysis method and Mapmaker/Exp software

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Chinese Science Bulletin 2006年第21期51卷 2619-2623页

作者： wu weiren HUANG Biguang College of Crop Science Fujian Agriculture and Forestry UniversityFuzhou350002 China

A qualitative trait is usually controlled by a single gene, but it may be sometimes controlled by two or even more genes. This phenomenon is called gene interaction. Rapidly searching for linked mo- lecular markers via bulked segregant analysis (BSA) and then constructing regional linkage map with Mapmaker/Exp has become a common approach to mapping single major genes. However, methods and computer programs developed for mapping single major genes cannot be simply applied to interactive genes because the genetic patterns of gene interac- tions are quite different from that of single-gene in- heritance. Up to now, experimental methods for quickly screening molecular markers linked to inter- active genes and statistical methods and corre- sponding computer softwares for simultaneously analyzing the linkage relationships of multiple mo- lecular markers to an interactive gene have not been available. To solve this problem, in this paper, we propose a strategy for mapping interactive genes using BSA and Mapmaker/Exp. We demonstrate that all interactive genes can be mapped by the 'BSA + Mapmaker/Exp' strategy using F2 generation (in a few cases, F3 generation is also needed). As BSA and Mapmaker/Exp have been broadly used in gene mapping studies and are well known by many re- searchers, the strategies proposed in this paper will be useful for practical researches.

关键词：基因相互作用基因作图制图软件安全

Angular velocity estimation using characteristics of star trails obtained by star sensor for spacecraft

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Science China(Information Sciences) 2021年第1期64卷 201-214页

作者： Xiaolin NING Pingping CHEN Yueqing HUANG weiren wu Jiancheng FANG School of Instrumentation Science & Opto-electronics Engineering Beihang University Lunar Exploration and Space Program Center China National Space Administration

Many studies have been conducted about angular velocity estimation using star sensors, and fairly good performance is achieved when the spacecraft is working at low-dynamic environments. However,when the spacecraft rotates at a large angular velocity, the star image will become blurred, which makes it difficult to identify and recognize star centroids, which, in turn, reduces the accuracy of angular velocity estimation. Therefore, to solve the problem with angular velocity estimation in highly dynamic situations,this research studies a method of angular velocity estimation using blurred star images. The length and ending point coordinates of star trails obtained from these blurred star images are used for a series of processes, which includes the pre-processing of blurred star images, determination of starting and ending points, thinning and selection of star trails, and calculation of trail lengths. Simulations show that the effectiveness of the proposed method in highly dynamic situations and the angular velocity estimation errors in constant and sinusoidal variation are reduced by at least 66% and 62%, respectively, compared with those of the traditional method.

关键词： angular velocity estimation star sensor blurred star images star trail characteristics unscented Kalman filter

Investigation on the development of deep space exploration

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Science China(Technological Sciences) 2012年第4期55卷 1086-1091页

作者： wu weiren LIU WangWang QIAO Dong JIE DeGang School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China Center of Lunar Exploration and Aerospace Engineering Beijing 100037China

Deep space exploration is the term used for the exploration of the Moon and the celestial bodies or space beyond the Moon, which is an important part of human space activities. Firstly, the development of deep space exploration (not including the Moon) during the last few decades is summarized. Secondly, the development trend of different space countries and regions is analyzed. Then the experience and enlightenment of deep space exploration are briefly discussed. Some suggestions for China's future deep space exploration are given in the end.

关键词： deep space exploration space program trend of development enlightenment

Overview of deep space laser communication

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Science China(Information Sciences) 2018年第4期61卷 7-18页

作者： weiren wu Ming CHEN Zhe ZHANG Xiangnan LIU Yuhui DONG School of Aerospace Engineering Beijing Institute of Technology Beijing Research Institute of Telemetry

The deep space probe is a vital technology for observing and exploring the universe. It is thus intensifying as an aerospace research focus on an international scale. Despite improving the frequency band,the conventional microwave communication technique has difficulty satisfying the increased demand for the enormous volume of scientific data returning to the Earth. With a carrier frequency that is several orders of magnitude higher than the microwave, free-space optical communication is a robust and promising method for achieving both high bit rates and long distances in deep space communication. In this article, the history of this technology is summarized and the objective laws are formulated, while key techniques and development trends are analyzed. Finally, useful concepts and suggestions are proposed for the development of deep space laser communication in China.

关键词： deep space communication deep space observation development process free space communication laser communication