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Robust optimization of nonlinear impulsive rendezvous with uncertainty

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Science China(Physics,Mechanics & Astronomy) 2014年第4期57卷 731-740页

作者： LUO YaZhong YANG Zhen li hengnian College of Aerospace Science and Engineering National University of Defense Technology State Key Laboratory of Astronautic Dynamics

The optimal rendezvous trajectory designs in many current research efforts do not incorporate the practical uncertainties into the closed loop of the design.A robust optimization design method for a nonlinear rendezvous trajectory with uncertainty is proposed in this *** performance index related to the variances of the terminal state error is termed the robustness performance index,and a two-objective optimization model(including the minimum characteristic velocity and the minimum robustness performance index)is formulated on the basis of the Lambert algorithm.A multi-objective,non-dominated sorting genetic algorithm is employed to obtain the Pareto optimal solution *** is shown that the proposed approach can be used to quickly obtain several inherent principles of the rendezvous trajectory by taking practical errors into ***,this approach can identify the most preferable design space in which a specific solution for the actual application of the rendezvous control should be chosen.

关键词： rendezvous and docking uncertainty robust optimization multi-objective evolutionary algorithm

Analysis of noncommensurate sampling effects on the performance of PN code tracking loops

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Science China(Technological Sciences) 2018年第6期61卷 893-905页

作者： YANG Jian YANG YiKang li JiSheng li hengnian YANG TianShe School of Electronic and Information Engineering Xi 'an Jiaotong University Xi 'an 710049 China State Key Laboratory Astronautic Dynamics (ADL) Xi 'an Satellite Control Center Xi 'an 710043 China Key Laboratory for Fault Diagnosis and Maintenance of Spacecraft in Orbit Xi 'an Satellite Control Center Xi 'an 710043 China

Noncoherent early-late processing （NELP） code tracking loops are often implemented using digital hardware for digital global positioning system （GPS） receivers. Noncommensurate sampling technology is widely used because it is viewed as an effective solution to cope with the drawback of digital effects. However, the relationship between the sampling rate and auto-correlation function （ACF） is not adequately characterized by traditional analysis. The principles for selecting the sampling rate are still not apparent. In order to solve this problem, we first analyzed the effects of different sampling rates on ACF and obtained the analytical form of a discrete auto-correlation function （DACF） for a noncommensurate sampling rate. Based on the result, the relationship between the step variation in DACF and NELP parameters such as sampling rate, integration time, and correlator spacing was determined. The maximum step variation size of DACF was also determined. However, considering the actual situation, additional factors such as code Doppler shift, precorrelation filter, and thermal noise may degrade the step variation of DACE The relationship between the step variation and these factors was analyzed separately. An appropriate sampling rate and appropriate correlator spacing were proposed to achieve the typical accuracy of measurement. The numerical simulation verified the validity of the above theoretical analyses, and finally, the conclusions and design constraints for the digital GPS receiver are summarized.

关键词： sampling rate code tracking loops heat dissipation GPS digital receiver

Analytical Propagation of Space Debris Density for Collisions near Sun-Synchronous Orbits

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Space(Science & Technology) 2022年第1期2022卷 245-261页

作者： Yongjie liu Yu Jiang hengnian li State Key Laboratory of Astronautic Dynamics Xi’an Satellite Control CenterXi’an 710043China

The increasing frequency of human launches has led to a dramatic increase in the amount of space debris,especially near sunsynchronous *** of the fragments are small in size,which may make tracking ***,characterizing the distribution,evolution,and collision risk of small debris has long been a difficult *** paper is aimed at investigating the orbital evolution and global dispersion behavior of debris clouds near sun-synchronous ***,the NASA breakup model is used to provide an initial distribution of small fragments after collision ***,the continuity equation is adopted to propagate the density variation ***,we introduce some statistical quantities and the entropy of debris clouds to model the randomness and band formation.A theorem concerning the equivalence of the band formation and maximal entropy is *** accuracy of the band formation time estimation is also *** noncatastrophic collisions at an altitude of 800 km due to a projectile with a mass of 100 g and a collision velocity of 1 km/s,we compare the analytical and numerical results of space debris *** results show that the maximal peak error is within 0.17,and the mean square error is about 0.25 at 400 ***,the entropy of right ascension of the ascending node is 8.5%less than that for debris clouds near an orbit with the same altitude and an inclination of 30 *** indicates the concentrating behavior for debris clouds near sun-synchronous orbits.

关键词： density. collision entropy

A novel satellite-equipped receiver for autonomous monitoring of GNSS navigation signal quality

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Science China(Technological Sciences) 2016年第7期59卷 1137-1146页

Global navigation satellite system(GNSS) comes with potential unavoidable application risks such as the sudden distortion or failure of navigation signals because its satellites are generally operated until failure. In order to solve the problems associated with these risks, receiver autonomous integrity monitoring(RAIM) and ground-based signal quality monitoring stations are widely used. Although these technologies can protect the user from the risks, they are expensive and have limited region coverage. Autonomous monitoring of satellite signal quality is an effective method to eliminate these shortcomings of the RAIM and ground-based signal quality monitoring stations; thus, a new navigation signal quality monitoring receiver which can be equipped on the satellite platform of GNSS is proposed in this paper. Because this satellite-equipped receiver is tightly coupled with navigation payload, the system architecture and its preliminary design procedure are first introduced. In theory, code-tracking loop is able to provide accurate time delay estimation of received signals. However, because of the nonlinear characteristics of the navigation payload, the traditional code-tracking loop introduces errors. To eliminate these errors, the dummy massive parallel correlators(DMPC) technique is proposed. This technique can reconstruct the cross correlation function of a navigation signal with a high code phase resolution. Combining the DMPC and direct radio frequency(RF) sampling technology, the satellite-equipped receiver can calibrate the differential code bias(DCB) accurately. In the meantime, the abnormities and failures of navigation signal can also be monitored. Finally, the accuracy of DCB calibration and the performance of fault monitoring have been verified by practical test data and numerical simulation data, respectively. The results show that the accuracy of DCB calibration is less than 0.1 ns and the novel satellite-equipped receiver can monitor the signal qualit

关键词： satellite-equipped receiver dummy massive parallel correlators(DMPC) differential code bias(DCB) signal quality monitoring

Mathematical prototypes for collocating geostationary satellites

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Science China(Technological Sciences) 2013年第5期56卷 1086-1092页

作者： li hengnian GAO ZhaoZhao li JiSheng li QuanJun XUE Dan li Donglin State Key Laboratory of Astronautic Dynamics(ADL) Xi'an Satellite Control Center Institute of Space System Engineering China Academy of Space Technology(CAST) Xi'an Satellite Control Center(XSCC)

Collocating geostationary satellites sharing the same position is much demanded for satellite operation recently,the separation strategies are adopted to safeguard the satellites collocated of leaving the relative distance beyond collision with different sets of orbit *** paper presents the mathematical prototypes which establish the allowable relative distance with uncertainty of orbital determination(OD),as well as the orbital element offset for each pair of collocated satellites,and puts forward algorithms to build such relationship to face the challenge of putting three satellites sharing the same position,the algorithms to allocate the longitude,eccentricity and inclination for each satellite are also given to ascertain that the mathematical prototypes are the guide specification to design collocation strategy for geostationary satellites.

关键词： geostationary satellite (GEO) satellite operation satellite collocation separation strategies

Determining origins of satellite breakup events in LEO region

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Astrodynamics 2023年第4期7卷 465-476页

作者： Yongjie liu Yu Jiang hengnian li Zongbo Huyan Hongchao Wang State Key Laboratory of Astronautic Dynamics Xi'an Satellite Control CenterXi'an 710043China

Currently,a surge in the number of spacecraft and fragments is observed,leading to more frequent breakup events in low Earth orbits(LEOs).The causes of these events are being identified,and specific triggers,such as collisions or explosions,are being examined for their importance to space traffic *** propagation methods were employed to trace the origins of these types of breakup *** were conducted using the NASA standard breakup model,and satellite Hitomi’s breakup was ***-Leibler(KL)divergences,Euclidean 2-norms,and Jensen-Shannon(JS)divergences were computed to deduce potential types of breakups and the associated fragmentation *** the simulated case,a discrepancy of 22.12 s between the estimated and actual time was ***,the breakup of the Hitomi satellite was estimated to have occurred around UTC 1:49:26.4 on March 26,*** contrasts with the epoch provided by the Joint Space Operation Center,which was estimated to be at 1:42 UTC±11 *** the findings,it was suggested that the techniques introduced in the study can be effectively used to trace the origins of short-term breakup events and to deduce the types of collisions and fragmentation masses under certain conditions.

关键词： breakup collision explosion Kullback-Leibler(KL)divergence Jensen-Shannon(JS)divergence

Design and optimization of low-energy transfer orbit to Mars with multi-body environment

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Science China(Technological Sciences) 2015年第10期58卷 1660-1671页

作者： LU Yi li hengnian li JiSheng CHE Zheng YANG YiKang YANG Yuan SUN Yang School of Electronic and Information Engineering Xi’an Jiaotong University State Key Laboratory of Astronautic Dynamics (ADL) Affiliated to Xi’an Satellite Control Center College of Aeronautics and Astronautics University of Electronic Science and Technology of China School of Aerospace Xi’an Jiaotong University

This paper discusses the problem of design and optimization of low-energy transfer orbit with multi-body environment. A new integrative method is proposed to effectively solve the problem, in which the parameterized patched manifolds in CR3BP(circular restricted three-body problems), the shape-based method with multi-body environment, the homotopic method with multi-body environment, and the low-thrust capturing and descending algorithm with multi-body environment are all included. Firstly, the parameters describing the patched manifolds in CR3 BP are optimized until the least total absolute velocity increment has been got, including the employment of the shape-based method with multi-body environment. Secondly, the low-thrust control laws of the transfer orbit are optimized employing the homotopic method with multi-body environment that transfers the fuel optimization problem to an easier energy optimization problem. Thirdly, the low-thrust descending orbit around Mars is computed using the laws proposed in this paper. As a typical example, the Earth-Mars transfer orbit design is discussed. The results showed that the parameters describing the patched manifolds could be optimized by the DE(differential evolution) algorithm effectively; the homotopic method with multi-body environment could get the optimal value that meets the first order optimality conditions; and the low-thrust descending orbit could effectively be captured by Mars and finally become a circular parking orbit around it by the hypothesis control laws proposed in this paper. It shows that the final fuel cost is much less than the optimal transfer in the patched two-body problems. In conclusion, the method proposed in this paper could effectively solve the low-energy low-thrust optimal control problem in multi-body environment for the future deep space explorations.

关键词： orbit optimization multi-body patched manifolds low-energy low-thrust

Stable periodic orbits for spacecraft around minor celestial bodies

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Astrodynamics 2018年第1期2卷 69-86页

作者： Yu Jiang Jurgen Arno Schmidt hengnian li Xiaodong liu Yue Yang State Key Laboratory of Astronautic Dynamics Xi'an Satellite Control CenterXi'an 710043China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China Astronomy Research Unit University of OuluFinland School of Software Engineering Xi'an Jiaotong UniversityXi'an 710049China

We are interested in stable periodic orbits for spacecraft in the gravitational eld of minor celestial *** stable periodic orbits around minor celestial bodies are useful not only for the mission design of the deep space exploration,but also for studying the long-time stability of small satellites in the large-size-ratio binary *** irregular shapes and gravitational elds of the minor celestial bodies are modeled by the polyhedral *** the topological classi cations of periodic orbits and the grid search method,the stable periodic orbits can be calculated and the topological cases can be ***,we nd ve di erent types of stable periodic orbits around minor celestial bodies:(1)stable periodic orbits generated from the stable equilibrium points outside the minor celestial body;(2)stable periodic orbits continued from the unstable periodic orbits around the unstable equilibrium points;(3)retrograde and nearly circular periodic orbits with zero-inclination around minor celestial bodies;(4)resonance periodic orbits;(5)near-surface inclined periodic *** take asteroids 243 Ida,433 Eros,6489 Golevka,101955 Bennu,and the comet 1P/Halley for examples.

关键词： asteroid comet deep space exploration periodic orbits stability orbit design

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应用观测新息和状态信息检测联合脉冲机动

国防科技大学学报 2014年第3期36卷 164-168页

作者：黄普钱山李恒年宇航动力学国家重点实验室陕西西安710043

针对提高空间机动目标跟踪精度的机动检测问题,提出一种新型机动检测方法——χ2-β检测法。该算法以脉冲前后沿为研究对象,通过分析观测新息和常推力α-β动力学模型中辅助变量β的物理特性,给出脉冲机动前后沿检测判据。仿真实验比较... 详细信息

针对提高空间机动目标跟踪精度的机动检测问题,提出一种新型机动检测方法——χ2-β检测法。该算法以脉冲前后沿为研究对象,通过分析观测新息和常推力α-β动力学模型中辅助变量β的物理特性,给出脉冲机动前后沿检测判据。仿真实验比较了χ2检测法和β检测法的特性,结果表明:χ2检测法,对机动前沿的敏感性与采样点和机动阀值相关,较多的采样点与较大的机动阀值可以降低虚警率,但会增加检测延时,反之,可以减小检测延时,但会增加虚警率;β检测法,对机动后沿的敏感性与滤波跟随性能相关,在测量精度的保证下,可对机动后沿准确检测。两种方法联合起来,可有效检测多种形式脉冲机动,性能优于传统的机动检测方法,具有一定的工程实用性。

关键词：机动检测 χ^2-β检测法 χ^2检测器 β检测器