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Trajectory Planning of High Precision Collaborative Robots

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Computer Modeling in Engineering & Sciences 2019年第3期118卷 583-598页

作者： tuanjie li Yan Zhang Jiaxing Zhou School of Mechano-Electronic Engineering Xidian UniversityXi’an710071China

In order to satisfy the high efficiency and high precision of collaborative robots,this work presents a novel trajectory planning ***,in Cartesian space,a novel velocity look-ahead control algorithm and a cubic polynomial are combined to construct the end-effector trajectory of ***,the joint trajectories can be obtained through the inverse *** order to improve the smoothness and stability in joint space,the joint trajectories are further adjusted based on the velocity look-ahead control algorithm and quintic ***,the proposed trajectory planning method is tested on a 4-DOF serial collaborative *** experimental results indicate that the collaborative robot achieves the high efficiency and high precision,which validates the effectiveness of the proposed method.

关键词： Collaborative robot high efficiency high precision velocity look-ahead control trajectory planning quintic B-spline

A nonlinear equivalent circuit method for analysis of passive intermodulation of mesh reflectors

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Chinese Journal of Aeronautics 2014年第4期27卷 924-929页

作者： Jiang Jie li tuanjie Ma Xiaofei Wang Pei School of Electromechanical Engineering Xidian University Xi’an Institute of Space Radio Technology

Passive intermodulation（PIM） has gradually become a serious electromagnetic interference due to the development of high-power and high-sensitivity RF/microwave communication systems, especially large deployable mesh reflector antennas. This paper proposes a field-circuit coupling method to analyze the PIM level of mesh reflectors. With the existence of many metal–metal（MM） contacts in mesh reflectors, the contact nonlinearity becomes the main reason for PIM generation. To analyze these potential PIM sources, an equivalent circuit model including nonlinear components is constructed to model a single MM contact so that the transient current through the MM contact point induced by incident electromagnetic waves can be calculated. Taking the electric current as a new electromagnetic wave source, the far-field scattering can be obtained by the use of electromagnetic numerical methods or the communication link method. Finally, a comparison between simulation and experimental results is illustrated to verify the validity of the proposed method.

关键词： Contact nonlinearity Equivalent circuit Mesh reflector Metal-metal contact Nonlinear distortion Passive intermodulation Scattering

Equilibrium state of axially symmetric electric solar wind sail at arbitrary sail angles

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Chinese Journal of Aeronautics 2024年第11期37卷 232-241页

作者： Chonggang DU Zheng H.ZHU Changqing WANG Aijun li tuanjie li School of Mechano-Electronic Engineering Xidian UniversityXi’an 710071China Department of Mechanical Engineering York UniversityOntario M3J 1P3Canada School of Automation Northwestern Polytechnical UniversityXi’an 710129China

This paper studies the equilibrium state and trajectory dynamics of an axially symmetric Electric solar wind sail(E-sail)at arbitrary sail *** E-sail is assumed operating in a heliocentric-ecliptic orbit at approximately one astronomic unit(au)from the Sun,and experiencing various dynamic disturbances like solar wind pressure,tether tension oscillations,and centrifugal *** study derives analytical expressions for the E-sail's equilibrium state and its maximal coning angle under small coning angle ***,an improved propulsion model is developed for the E-sail in this equilibrium *** assess the precision of these formulations,a high-fidelity E-sail dynamic model is constructed using the nodal position finite element method,where the tethers are modeled as two-noded tensile elements and the central spacecraft and remote units are simplified as lumped *** thorough parametric analyses,this paper conclusively demonstrates that the operation of the E-sail at the equilibrium state can be achieved in accordance with the derived analytical prediction of the equilibrium ***,the improved propulsion model is employed in trajectory analyses for a mission to reach the solar system's *** study provides valuable insights and findings and foundation for the practical application and further advancement of the E-sail technology.

关键词： Electric solar wind sail Extremely flexible system Multi-body dynamics Harmonic motion Maximum coning angle Equilibrium configuration Improved propulsion model High-fidelity modeling

Form-fnding methods for deployable mesh reflector antennas

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Chinese Journal of Aeronautics 2013年第5期26卷 1276-1282页

作者： li tuanjie Jiang Jie Deng Hanqing lin Zhanchao Wang Zuowei School of Electromechanical Engineering Xidian University

Deployable high-frequency mesh reflector antennas for future communications and obser- vations are required to obtain high gain and high directivity. In order to support these new missions, reflectors with high surface accuracy are widely required. The form-finding analysis of deployable mesh reflector antennas becomes more vital which aims to determine the initial surface profile formed by the equilibrium prestress distribution in cables to satisfy the surface accuracy requirement. In this paper, two form-finding methods for mesh reflector antennas, both of which include two steps, are pro- posed. The first step is to investigate the prestress design only for the cable net structure as the circum- ferential nodes connected to the supporting truss are assumed fixed. The second step is to optimize the prestress distribution of the boundary cables connected directly to the supporting truss considering the elastic deformation of the antenna structure. Some numerical examples are carried out and the simulation results demonstrate the proposed form-finding methods can warrant the deformed antenna reflector surface matches the one by design and the cable tension forces fall in a specified range.

关键词： Antenna reflectors Cable net structure Elastic deformation Form-finding analysis Mesh reflector Prestress distribution

Evaluation of E-sail parameters on central spacecraft attitude stability using a high-fidelity rigid–flexible coupling model

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Astrodynamics 2024年第2期8卷 271-284页

作者： Chonggang Du Zheng H.Zhu Changqing Wang Aijun li tuanjie li School of Electro-Mechanical Engineering Xidian UniversityXi’an 710071China Department of Mechanical Engineering York University4700 Keele StreetTorontoOntario M3J 1P3Canada School of Automation Northwestern Polytechnical UniversityXi’an 710129China

This study examines the impact of electric solar wind sail(E-sail)parameters on the attitude stability of E-sail’s central spacecraft by using a comprehensive rigid–flexible coupling dynamic *** this model,the nodal position finite element method is used to model the elastic deformation of the tethers through interconnected two-node tensile *** attitude dynamics of the central spacecraft is described using a natural coordinate *** rigid–flexible coupling between the central spacecraft and its flexible tethers is established using Lagrange *** research reveals the significant influences of parameters such as tether numbers,tether’s electric potential,and solar wind velocity on attitude ***,solar wind fluctuations and the distribution of electric potential on the main tethers considerably affect the attitude stability of the *** consistent management,the angular velocities of the spacecraft must remain at target ***,the attitude stability of a spacecraft has a pronounced dependence on the geometrical configuration of the E-sail,with axisymmetric E-sails proving to be more stable.

关键词： electric solar wind sail(E-sail) space tether nodal position finite element method(NPFEM) natural coordinate formulation (NCF) attitude stability

The Origin,Historical Variations,and Distribution of Heavy Metals in the Qiongzhou Strait and Nearby Marine Areas

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Journal of Ocean University of China 2017年第2期16卷 262-268页

作者： ZHANG Zhiqiang CHEN liang WANG Weiping li tuanjie ZU Tingting Guangzhou Institute of Geochemistry Chinese Academy of Sciences:CAS Key Laboratory of Marginal Sea GeologyGuangzhou 510640P.R.China South China Sea Branch of State Oceanic Administration Guangzhou 510300P.R.China South China Sea Branch Institute of Oceanology Chinese Academy of SciencesGuangzhou 510301P.R.China

We analyzed heavy metal concentrations in a number of surface sediments and cores from the Qiongzhou Strait and surrounding marine *** areas of high concentrations are primarily outside the eastern mouth of the Qiongzhou Strait and on the west side of the Leizhou Peninsula,whereas the areas of low concentrations are located primarily in the eastern Qiongzhou *** maximum Cd,Pb and Zn concentrations in the samples collected in our study do not exceed the official standards for marine sediments,whereas the concentrations of Cr and Cu slightly exceed the *** exist between the concentrations of Cu,Pb,Zn,Cr and Cd,and the concentrations of these metals are positively correlated with the mean particle size(φ value),indicating that the finer sediments have adsorbed greater amounts of heavy metal elements than the coarser *** evaluation of the potential environmental risks demonstrates that certain indices of heavy metal pollution and environmental risks are relatively low and may be assigned low risk levels,thereby indicating that,in terms of heavy metals,the marine sedimentary environment in this region is only mildly *** analysis of the contaminant origins shows that the heavy metals in this region primarily originate in the Pearl River Estuary and that a small amount of them is derived from local *** elevated heavy metal concentrations from the upper sections of the cores started 130 years ago,which indicats that heavy metals in the surface sediments are primarily due to human activities associated with industrialization.

关键词： heavy metals sediment origin Qiongzhou Strait

Surface pollen distribution patterns in Beibu Gulf and corresponding sediment dynamics environment

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Chinese Science Bulletin 2012年第8期57卷 902-911页

作者： TONG GuoBan CHEN lian LONG JiangPing li tuanjie XIAO XiaYun TONG SongMei lnxtituta of Hvdrooeologv and Environmental Geoloev.Chinese Academy of Geological Sciences Shijiazhuang 050061China South China Sea Marine Engineering Surveying Center State Oceanic AdministrationGuangzhou 510300China Second Institute of Oceanography State Oceanic AdministrationHangzhou 310012China State Key Laboratory of Lake Science and Environments Nanjing Institute of Geography and LimnologyChinese Academy of SciencesNanjing 210008China

The Beibu Gulf is a semi-enclosed gulf in the northwest of the South China *** palynologically analyzed 306 surface sediment samples from the eastern Beibu Gulf to improve bioclimatic interpretation of fossil pollen records *** pollen assemblages could be classified into five pollen regions based on the distributions of total,arboreal,herbaceous and fern pollen *** high-concentration and three low-concentration subregions could be distinguished within these *** distribution patterns of surface pollen assemblages were consistent with those of grain sizes of surface *** from regions with high pollen concentrations were very fine and fine silts (>7.0,0.088 mm).Sedimentary heterogeneity of surface pollen assemblages was closely related to pollen source,transportation and sedimentation controlled by ocean currents,tides and waves,and oceanic bottom *** spores exhibited higher percentages along the east margins of the region,while arboreal types like Pinus increased in concentration towards the *** pollen appeared in high percentages around seacoasts near their source *** and mangrove pollen were distributed near their source regions at low *** discuss the sediment dynamic environments in the eastern Beibu Gulf based on surface pollen *** estuary region is an important access to the sea basin and a depositional site for terrestrial pollen *** regions can accumulate pollen due to the back-and-forth movements of tides *** ocean currents on a gulf scale tend to spread pollen grains,the interaction of multiple currents could lead to pollen accumulation and *** surface pollen concentrations in the northeast shallow-water regions of the eastern Beibu Gulf could be attributed to repeated washing and sediment floatation caused by severe wave activities duri

关键词：花粉浓度分布格局北部湾动力学环境表面泥沙表层沉积物蕨类植物

Potential Submarine Geologic Hazards at the Entrance of the Pearl River Estuary in the Northern South China Sea

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Journal of Ocean University of China 2016年第4期15卷 606-612页

作者： ZHANG Zhiqiang WEI Zhiqiang HE Huizhong WEI Wei QIAN libing li tuanjie Guangzhou Institute of Geochemistry Chinese Academy of Sciences CAS Key Laboratory of Marginal Sea GeologyGuangzhou 510640 P. R. China South China Sea Branch of State Oceanic Administration Guangzhou 510300 P. R. China

The potential submarine geologic hazards were distinguished and categorized at the entrance of the Pearl River Estuary in the northern South China Sea, based upon the analysis of side scan sonar and sub-bottom profiler surveying data of about 2500 km long, in an area about 2000 km^2 around the Wanshan Archipelago. The data obtained in the survey has the highest spatial resolution by far, which could reveal more detailed distributions and characteristics of the geologic hazards than before. In the study region, three paleo-channels that were buried about 10–30 m below the seabed were found; more than 10 shallow gas areas were discovered. The sand waves found in the region were generally small and located near the islands, and twenty pockmarks found on the seabed were mostly concentrated to north of Zhuzhou island. There are also many man-made obstacles in the region, such as wreckages, pipeline, etc. In this paper we provide a detailed distribution map of the submarine geologic hazards in this region for the first time, and discuss their formation and harmfulness, which will provide a scientific basis for marine engineering construction, marine geologic disaster prevention and mitigation.

关键词： geologic Pearl buried shallow submarine mostly mitigation north disaster sonar

Recent Advances in Space-Deployable Structures in China

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Engineering 2022年第10期17卷 207-219页

作者： Xiaofei Ma tuanjie li Jingya Ma Zhiyi Wang Chuang Shi Shikun Zheng Qifeng Cui Xiao li Fan liu Hongwei Guo liwu liu Zuowei Wang Yang li Xi’an Institute of Space Radio Technology Xi’an 710100China School of Electromechanical Engineering Xidian UniversityXi’an 710071China Beijing Institute of Spacecraft System Engineering Beijing 100094China Aerospace System Engineering Shanghai Shanghai 201109China State Key Laboratory of Robotics Harbin Institute of TechnologyHarbin 150001China Department of Astronautical Science and Mechanics Harbin Institute of TechnologyHarbin 150001China

Deployable space structure technology is an approach used in building spacecraft,especially when realizing deployment and folding *** in orbit,the structures are released from the fairing,deployed,and *** the development of communication,remote-sensing,and navigation satellites,space-deployable structures have become cutting-edge research topics in space science and *** paper summarizes the current research status and development trend of spacedeployable structures in China,including large space mesh antennas,space solar arrays,and deployable structures and mechanisms for deep-space *** technologies of space-deployable structures are addressed from the perspectives of deployable mechanisms,cable-membrane form-finding,dynamic analysis,reliable environmental adaptability analysis,and ***,future technology developments and trends are elucidated in the fields of mesh antennas,solar arrays,deployable mechanisms,and on-orbit adjustment,assembly,and construction.

关键词： Deployable space structures Mesh antennas Solar arrays Deep-space exploration