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Target localization method of non-cooperative spacecraft on on-orbit service

Chinese Journal of Aeronautics 2022年第11期35卷 336-348页

作者： Yingxiao LI Ju HUO Ping MA Ruiye JIANG Control and Simulation Center Harbin Institute of TechnologyHarbin 150001 China

With the explosion of the number of meteoroid/orbital debris in terrestrial space in recent years, the detection environment of spacecraft becomes more complex. This phenomenon causes most current detection methods based on machine learning intractable to break through the two difficulties of solving scale transformation problem of the targets in image and accelerating detection rate of high-resolution images. To overcome the two challenges, we propose a novel noncooperative target detection method using the framework of deep convolutional neural network.Firstly, a specific spacecraft simulation dataset using over one thousand images to train and test our detection model is built. The deep separable convolution structure is applied and combined with the residual network module to improve the network’s backbone. To count the different shapes of the spacecrafts in the dataset, a particular prior-box generation method based on K-means cluster algorithm is designed for each detection head with different scales. Finally, a comprehensive loss function is presented considering category confidence, box parameters, as well as box confidence. The experimental results verify that the proposed method has strong robustness against varying degrees of luminance change, and can suppress the interference caused by Gaussian noise and background complexity. The mean accuracy precision of our proposed method reaches 93.28%, and the global loss value is 13.252. The comparative experiment results show that under the same epoch and batchsize, the speed of our method is compressed by about 20% in comparison of YOLOv3, the detection accuracy is increased by about 12%, and the size of the model is reduced by nearly 50%.

关键词： Spacecraft service High resolution image Object detection Complex environment Lightweight model

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Novel camera calibration method based on invariance of collinear points and pole-polar constraint

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Journal of Systems Engineering and Electronics 2023年第3期34卷 744-753页

作者： WEI Liang ZHANG Guiyang huo ju XUE Muyao School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin 150001China School of Mechanical Engineering Changshu Institute of TechnologySuzhou 215500China Space Propulsion Technology Research Institute Shanghai Academy of Spaceflight TechnologyShanghai 201109China

To address the eccentric error of circular marks in camera calibration,a circle location method based on the invariance of collinear points and pole–polar constraint is proposed in this paper.Firstly,the centers of the ellipses are extracted,and the real concentric circle center projection equation is established by exploiting the cross ratio invariance of the collinear points.Subsequently,since the infinite lines passing through the centers of the marks are parallel,the other center projection coordinates are expressed as the solution problem of linear equations.The problem of projection deviation caused by using the center of the ellipse as the real circle center projection is addressed,and the results are utilized as the true image points to achieve the high precision camera calibration.As demonstrated by the simulations and practical experiments,the proposed method performs a better location and calibration performance by achieving the actual center projection of circular marks.The relevant results confirm the precision and robustness of the proposed approach.

关键词： camera calibration cross ratio invariance infinite lines eccentricity error compensate

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Information entropy-based fitting of the disease trajectory of brain ischemia-induced vascular cognitive impairment

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Neural Regeneration Research 2012年第9期7卷 697-702页

作者： Lin Liu Ju HUO Ying Zhao Yu Tian College of Pharmacy Harbin University of Commerce Harbin 150076 Heilongjiang Province China Department of Electrical Engineering Harbin Institute of Technology Harbin 150001 Heilongjiang Province China

The present study investigated the disease trajectory of vascular cognitive impairment using the entropy of information in a neural network mathematical simulation based on the free radical and excitatory amino acids theories. Glutamate, malondialdehyde, and inducible nitric oxide synthase content was significantly elevated, but acetylcholine, catalase, superoxide dismutase, glutathione peroxidase and constitutive nitric oxide synthase content was significantly decreased in our vascular cognitive impairment model. The fitting curves for each factor were obtained using Matlab software. Nineteen, 30 and 49 days post ischemia were the main output time frames of the influence of these seven factors. Our results demonstrated that vascular cognitive impairment involves multiple factors. These factors include excitatory amino acid toxicity and nitric oxide toxicity. These toxicities disrupt the dynamic equilibrium of the production and removal of oxygen free radicals after cerebral ischemia, reducing the ability to clear oxygen free radicals and worsening brain injury.

关键词： vascular cognitive impairment bilateral ligation of the common carotid artery acetylcholine nitric oxide synthase free radical glutamate

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Multi-camera calibration method based on minimizing the difference of reprojection error vectors

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Journal of Systems Engineering and Electronics 2018年第4期29卷 844-853页

作者： huo ju LI Yunhui YANG Ming School of Electrical Engineering Harbin Institute of Technology Control and Simulation Center Harbin Institute of Technology

In order to achieve a high precision in three-dimensional（3D） multi-camera measurement system, an efficient multi-cameracalibration method is proposed. A stitching method of large scalecalibration targets is deduced, and a fundamental of multi-cameracalibration based on the large scale calibration target is provided.To avoid the shortcomings of the method, the vector differencesof reprojection error with the presence of the constraint conditionof the constant rigid body transformation is modelled, and mini-mized by the Levenberg-Marquardt （LM） method. Results of thesimulation and observation data calibration experiment show thatthe accuracy of the system calibrated by the proposed methodreaches 2 mm when measuring distance section of 20 000 mmand scale section of 7 000 mm × 7 000 mm. Consequently, theproposed method of multi-camera calibration performs better thanthe fundamental in stability. This technique offers a more uniformerror distribution for measuring large scale space.

关键词： vision measurement multi-camera calibration field stitching vector error

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Atmospheric fate of typical liquid crystal monomers in the tropospheric gas,liquid,and granular phases

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Journal of Environmental Sciences 2024年第2期136卷 348-360页

作者： Yanru huo Zexiu An Mingxue Li Jinchan Jiang Yuxin Zhou ju Xie Jianguo Zhang Maoxia He Environment Research Institute Shandong UniversityQingdao 266237China College of Plant Protection Hebei Agricultural UniversityBaoding 071000China School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China Jinan Environmental Research Academy Jinan 250000China

Mineral aerosol particles significantly impact environmental risk prediction of liquid crystal monomers(LCMs).In this work,we investigated the reaction mechanisms and kinetics of three typical LCMs(4-cyano-3,5-difluorophenyl 4-ethylbenzoate(CEB-2F),4-cyano-3-fluorophenyl 4-ethylbenzoate(CEB-F),and 4-cyanophenyl 4-ethylbenzoate(CEB))with ozone(O_(3))in the atmospheric gas,liquid,and particle phases employing density functional theory(DFT).Here,O_(3)is prone to add to the benzene ring without F atom(s)in the selected LCMs.The ozonolysis products are aldehydes,carboxylic acids,epoxides,and unsaturated hydrocarbons containing aromatic rings.Those products undergo secondary ozonolysis to generate small molecular compounds such as glyoxal,which is beneficial for generating secondary organic aerosol(SOA).Titanium dioxide(TiO_(2)),an essential component of mineral aerosol particles,has good adsorption properties for LCMs;however,it slightly reduces the reactivity with O_(3).At 298 K,the reaction rate constant of the selected LCMs reacting with O_(3)in the gas and atmospheric liquid phases is(2.74–5.53)×10^(-24)cm^(3)/(mol·sec)and 5.58×10^(-3)–39.1 L/(mol·sec),while CEB-2F reacting with O_(3)on(TiO_(2))_(6)cluster is 1.84×10^(-24)cm^(3)/(mol·sec).The existence of TiO_(2)clusters increases the persistence and long-distance transportability of LCMs,which enlarges the contaminated area of LCMs.

关键词： Liquid crystal monomers(LCMs) Ozonolysis TiO_(2)clusters Adsorption Toxicity assessment

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Non-cooperative target pose estimation based on improved iterative closest point algorithm

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Journal of Systems Engineering and Electronics 2022年第1期33卷 1-10页

作者： ZHU Zijian XIANG Wenhao huo ju YANG Ming ZHANG Guiyang WEI Liang Department of Astronautics Harbin Institute of TechnologyHarbin 150006China Department of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin 150006China Systems Engineering Research Institute China State Shipbuilding Corporation LimitedBeijing 100036China

For localisation of unknown non-cooperative targets in space,the existence of interference points causes inaccuracy of pose estimation while utilizing point cloud registration.To address this issue,this paper proposes a new iterative closest point(ICP)algorithm combined with distributed weights to intensify the dependability and robustness of the non-cooperative target localisation.As interference points in space have not yet been extensively studied,we classify them into two broad categories,far interference points and near interference points.For the former,the statistical outlier elimination algorithm is employed.For the latter,the Gaussian distributed weights,simultaneously valuing with the variation of the Euclidean distance from each point to the centroid,are commingled to the traditional ICP algorithm.In each iteration,the weight matrix W in connection with the overall localisation is obtained,and the singular value decomposition is adopted to accomplish high-precision estimation of the target pose.Finally,the experiments are implemented by shooting the satellite model and setting the position of interference points.The outcomes suggest that the proposed algorithm can effectively suppress interference points and enhance the accuracy of non-cooperative target pose estimation.When the interference point number reaches about 700,the average error of angle is superior to 0.88°.

关键词： non-cooperative target pose estimation iterative closest point(ICP) Gaussian weight

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High Precision and Noise Resistance Estimation Based on Optimized GOI Algorithm for Rocket Nozzle

High Precision and Noise Resistance Estimation Based on Opti...

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第37届中国控制会议

作者： Xing Zhou Ju HUO Guiyang Zhang School of Electrical Engineering and Automation Harbin Institute of Technology School of Astronautics Harbin Institute of Technology

This paper is concerned with the rocket nozzle working environment with many interference factors, upon which a high precision and noise resistance algorithm for pose estimation is proposed. The optimized generalized orthogonal iterative（GOI） algorithm is utilized for iterative solution such that it avoids the poor convergence or convergence failure problem caused by the weak perspective projection. The proposed technique only needs to observe the rocket nozzle at different orientations and the objective function based on the collinear error is established, thus the estimated parameters can be obtained subsequently. Finally, simulation and practical experiments are carried out simultaneously. By using the improved algorithm, within a space of 2 m u2 m u4 m, the maximum static error of the swing angles is superior to 0.085 and the maximum dynamic error is less than 0.13°. The results verify the high accuracy and noise resistance performance of the proposed approach.

关键词： Binocular vision CCD camera pose estimation optimized GOI algorithm rocket nozzle

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Pose measurement of small-size aircraft based on machine vision

Pose measurement of small-size aircraft based on machine vis...

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第40届中国控制会议

作者： Yunhui Li Ou Fang Zhonghua Miao Ju HUO School of Mechatronic Engineering and Automation Shanghai University School of Electrical Engineering and Automation Harbin Institute of Technology

In small-size aircraft ground tests,pose measurement is significant for the validation of aircraft control and guidance algorithm development and performance evaluation.In order to achieve a precise value of the pose in the aircraft ground test,Firstly,an aircraft ground test localization system based on machine vision has been established and proposed a global localization method for the smaller sizes of aircraft ground test.Multi-view matching of feature points is realized by using the spatiotemporal consistency method.The method of uncertainty analysis is used to realize the high precision 3D reconstruction of feature points from multiple views.The pose parameters of the aircraft are solved by using the pose estimation algorithm of non-collinear vectors.The feasibility and accuracy of the pose measurement algorithm are verified by simulation and actual experiment.The experimental results show that:under the condition of the measurement range is 6000 mm×6000 mm×3000 mm,the size of the aircraft is about 400 mm,and the 3D positioning accuracy of the feature points is 2.9 mm,the theoretical accuracy of the pose measurement algorithm based on vector crossover can reach 0.5°（3σ） and 3 mm（3σ） respectively.The actual relative measurement accuracy up to 1.3 °（3σ） and 4 mm（3σ）.It meets the requirements of stable and reliable performance evaluation,high precision,and strong anti-jamming ability of small-size aircraft guidance and control system.

关键词： Machine vision Ground test of aircraft Pose estimation Vector cross

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“距离”与艺术实践:阿尔都塞文艺批评中“群众”概念的展开

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文艺理论研究 2020年第3期41卷 201-209页

作者：霍炬陕西师范大学文学院陕西省西安市710119

阿尔都塞对政治性的"群众"概念进行了理论厘清,申明在斗争中被联合起来的各阶级群众既是行动起点,也是理论归宿,因此在"西方马克思主义"的思想脉络中独树一帜。本文从文艺批评论述出发,强调阿尔都塞对当代批评理论中的"作者""形式"和"... 详细信息

阿尔都塞对政治性的"群众"概念进行了理论厘清,申明在斗争中被联合起来的各阶级群众既是行动起点,也是理论归宿,因此在"西方马克思主义"的思想脉络中独树一帜。本文从文艺批评论述出发,强调阿尔都塞对当代批评理论中的"作者""形式"和"间离效果"等概念的重新定位,用"距离"理论说明围绕着群众运动的意识形态实践如何介入现实和发挥现实功能,对"群众"概念的历史脉络、阿尔都塞文艺批评的理论斗争内容、他在当时新艺术实践中发现的积极内容以及哲学-艺术实践整体中的有机联系等问题展开论述。

关键词：阿尔都塞群众距离意识形态

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Calibration of Camera with Large Field-of-View Based on Flexible Planar Target

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Journal of Harbin Institute of Technology(New Series) 2013年第4期20卷 14-20页

作者： Ju HUO Wen-Bo Dong Ning Yang Wu-Kang Lin Dept.of Electrical Engineering Harbin Institute of Technology Control and Simulation Center Harbin Institute of Technology

For high precision calibration of camera with large field-of-view,massive calibration points will be needed if traditional methods are selected,which makes the calibration complex and time-consuming.In order to solve this problem,a calibration method based on flexible planar target is proposed.In this method,distortion factor is firstly acquired by the invariance of cross ratio,and existing feature points are adjusted with the distortion factor.Then,a large number of points that will be used for the calibration are constructed with the adjusted feature points.Simultaneously,Tsai method is modified so as to reduce the complexity of calibration,which makes the process linear.The simulation and real experiments show that the method proposed in this paper is simple,linear,accurate and robust,and the precision of this method is close to that of Tsai method using abundant points.The method can satisfy the requirement of high precision calibration for camera with large field-of-view.

关键词： large field-of-view calibration distortion factor flexible planar target linear two-step method

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