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Design,Modeling and Experimentation of a Biomimetic Wall-climbing Robot for Multiple Surfaces

Journal of Bionic Engineering 2020年第3期17卷 523-538页

作者： Jinfu Liu Linsen xu jiajun xu Tao Li Shouqi Chen Hong xu Gaoxin Cheng Marco Ceccarelli Institute of Advanced Manufacturing Technology Hefei Institutes of Physical ScienceCASChangzhou 213164China Department of Precision Machinery and Precision Instrumentation University of Science and Technology of ChinaHefei 230026China Anhui Province Key Laboratory of Biomimetic Sensing and Advanced Robot Technology Hefei 230026China Department of Industrial Engineerings University of Rome Tor Vergata Via del Politecnico 100133RomaItaly

Wall-climbing robots can work on steep terrain and obtain environment information in three dimensions for human in real time,which can improve operation ***,traditional single-mode robots cannot ensure the stable attachment on complex wall *** by the structure characteristics of flies and clingfishes,three bionic structures including the flexible spine wheel,the adhesive material and the adsorption system are *** at task requirements on multiple walls and based on the above three bionic structures,a wall-climbing robot with the composed mode of“grabbing+adhesion+adsorption”is presented v/a the law of mechanism configuration *** static analysis,the safe attachment conditions for the robot on smooth and rough walls are that the adsorption force is 30 N or *** on Newton's Euler and Lagrange formulas,the dynamic equations of the robot on vertical walls are established to deduce that the maximum theoretical torque of the driving motor is 1.43 N·m at a uniform ***,the prototype of the wall-climbing robot is manufactured and tested on the vertical lime wall,coarse sandpaper wall and acrylic ceiling ***,experiment results imply that the average maximum moving speed and the corresponding load are 7.19 cm·s-1 and 0.8 kg on the vertical lime wall,7.78 cm·s-1 and 0.6 kg on the coarse sandpaper wall,and 5.93 cm·s-1 and 0.2 kg on the acrylic ceiling wall *** findings could provide practical reference for the robot’s application on walls.

关键词： wall-climbing robot spine wheel adhesive material adsorption system

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WeldNet:A voxel-based deep learning network for point cloud annular weld seam detection

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Science China(Technological Sciences) 2024年第4期67卷 1215-1225页

作者： WANG Hui RONG YouMin xu jiajun XIANG SongMing PENG YiFan HUANG Yu State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China School of Mechanical Science and Engineering Huazhong University of Science and TechnologyWuhan 430074China

Weld seam detection is an important part of automated *** present,few studies have been conducted on annular weld seams,and a lot of defects exist in the point cloud model of the tube sheet obtained by RGB-D cameras and photography *** at the above problems,this paper proposed an annular weld seam detection network named WeldNet where a voxel feature encoding layer was adaptively improved for annular weld seams,the sparse convolutional network and region proposal network(RPN)were used to detect annular weld seam position,and an annular weld seam detection loss function was ***,an annular weld seam dataset was established to train the *** with the random sampling consistency(RANSAC)method,WeldNet has a higher detection accuracy,as well as a higher detection success rate which has increased by 23%.Compared with U-Net,WeldNet has been proven to achieve a better detection result,and the intersection over the union of the weld seam detection is improved by 17.8%.

关键词： deep learning point cloud weld seam detection welding annular weld seam

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Symplectic Conditions on Grassmannian,Flag,and Schubert Varieties

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Communications in Mathematical Research 2024年第2期40卷 154-190页

作者： jiajun xu Guanglian Zhang School of Mathematical Sciences Shanghai Jiao Tong UniversityShanghai 200240China.

In this paper,a description of the set-theoretical defining equations of symplectic(type C)Grassmannian/flag/Schubert varieties in corresponding(type A)algebraic varieties is given as linear polynomials in Plucker coordinates,and it is proved that such equations generate the defining ideal of variety of type C in those of type *** applications of this result,the number of local equations required to obtain the Schubert variety of type C from the Schubert variety of type A is computed,and further geometric properties of the Schubert variety of type C are given in the aspect of complete ***,the smoothness of Schubert variety in the non-minuscule or cominuscule Grassmannian of type C is discussed,filling gaps in the study of algebraic varieties of the same type.

关键词： Grassmannian variety generalized flag variety Schubert variety Plucker embedding complete intersection.

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Design and Theoretical Research on Aerial-Aquatic Vehicles:A Review

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Journal of Bionic Engineering 2023年第6期20卷 2512-2541页

作者： Yi Sun xuefei Liu Kai Cao Huan Shen Qian Li Guangming Chen jiajun xu Aihong Ji Lab of Locomotion Bioinspiration and Intelligent Robots College of Mechanical and Electrical EngineeringState Key Laboratory of Mechanics and Control for Aerospace StructuresNanjing University of Aeronautics and Astronautics29 Yudao StreetNanjing210016China State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

With the rapid development of unmanned aerial and underwater vehicles,various tasks,such as biodiversity monitoring,surveying,and mapping,as well as,search and rescue can now be completed in a single medium,either underwater or in the *** systematically examining the water–air cross-medium locomotion of organisms,there has been growing interest in the development of aerial-aquatic *** goal of this review is to provide a detailed outline of the design and cross-medium theoretical research of the existing aerial-aquatic vehicles based on the research on the organisms capable of transiting between water and *** these designs and theoretical frameworks have been validated in many aerial-aquatic vehicles,there are still many problems that need to be addressed,such as inflexible underwater motion and unstable medium *** a result,supplementation of the existing cross-medium biomimetic research,vehicle design,power selection,and cross-medium theory is urgently required to optimize the key technologies in ***,by summarizing the existing designs and theoretical approaches on aerial-aquatic vehicles,including biomimetic research on water–air cross-medium locomotion in nature,different power selections,and cross-medium theoretical research,the relative problems and development trends on aerial-aquatic vehicles were thoroughly explored,providing significant help for the subsequent research process.

关键词： Aerial-aquatic vehicle Cross-medium motion Power selection Control theory Biomimetic

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A Spark Scheduling Strategy for Heterogeneous Cluster

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Computers, Materials & Continua 2018年第6期55卷 405-417页

作者： xuewen Zhang Zhonghao Li Gongshen Liu jiajun xu Tiankai Xie Jan Pan Nees School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai200240P.R.C. Eberly College of Science Pennsylvania State UniversityOld MainState CollegePA 16801U.S.A.

As a main distributed computing system,Spark has been used to solve problems with more and more complex ***,the native scheduling strategy of Spark assumes it works on a homogenized cluster,which is not so effective when it comes to heterogeneous *** aim of this study is looking for a more effective strategy to schedule tasks and adding it to the source code of *** investigating Spark scheduling principles and mechanisms,we developed a stratifying algorithm and a node scheduling algorithm is proposed in this paper to optimize the native scheduling strategy of *** this new strategy,the static level of nodes is calculated,the dynamic factors such as the length of running tasks,and CPU usage of work nodes are considered *** through a series of comparative experiments in alienation cluster,the new strategy costs less running time and lower CPU usage rate than the original Spark strategy,which verifies that the new schedule strategy is more effective one.

关键词： Spark optimize scheduling stratifying algorithm performance optimization

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An unusual cause of cyanosis after intra-extra cardiac Fontan procedure: anastomotic leakage between conduit and inferior vena cava

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World Journal of Pediatric Surgery 2023年第4期6卷 282-284页

作者： jiajun xu Weize xu Jin Yu Shanshan Shi Qiang Shu Zhuo Shi Department of Cardiac Intensive Care Unit(CICU) Children’s HospitalZhejiang University School of MedicineNational Clinical Research Center for Child HealthHangzhouZhejiangChina Department of Cardiac Surgery Children’s HospitalZhejiang University School of MedicineNational Clinical Research Center for Child HealthHangzhouZhejiangChina Department of Ultrasound Diagnosis Children’s HospitalZhejiang University School of MedicineNational Clinical Research Center for Child HealthHangzhouZhejiangChina

A child aged 7 years was admitted to our hospital nearly 5 years after an intra-extra cardiac Fontan operation due to aggravated *** was diagnosed with pulmonary atresia(PA),atrial septal defect,patent ductus arteriosus(PDA)and thickened tricuspid valve with severe regurgitation 1 month after being born,which was considered PA with intact ventricular septum(IVS)with severely hypoplastic right ventricle and was similar to functional single ventricle.

关键词： admitted cardiac septal

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Wheel-legged In-pipe Robot with a Bioinspired Hook and Dry Adhesive Attachment Device

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Journal of Bionic Engineering 2024年第3期21卷 1208-1222页

作者： Yahong Liu Yi Sun Kai Cao Shutao Wu Xiaofeng xu Qingfei Han Shikun Wen Huan Shen Guangming Chen jiajun xu Zhiwei Yu Aihong Ji Lab of Locomotion Bioinspiration and Intelligent Robots College of Mechanical and Electrical EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In-pipe robots have been widely used in pipes-with smooth inner ***,current in-pipe robots face challenges in terms of moving past obstacles and climbing in marine-vessel pipeline systems,which are affected by marine biofouling and electrochemical *** paper takes inspiration from the dual-hook structure of Trypoxylus dichotomus’s feet and gecko‑like dry adhesives,proposing an in-pipe robot that is capable of climbing on rough and smooth pipe *** combination of the bioinspired hook and dry adhesives allows the robot to stably attach to rough or smooth pipe inwalls,while the wheel-leg hybrid mechanism provides better conditions for obstacle *** paper explores the attachment and obstacle-surmounting mechanisms of the ***,motion strategies for the robot are devised based on different pipe structural *** experiments showed that this robot can adapt to both smooth and rough pipe environments simultaneously,and its motion performance is superior to conventional driving *** robot’s active turning actuators also enable it to navigate through horizontally or vertically oriented 90°bends.

关键词： In-pipe robot Bioinspired attachment device Wheel-legged robot Mechanical design

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Human-robot interface based on sEMG envelope signal for the collaborative wearable robot

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Biomimetic Intelligence & Robotics 2023年第1期3卷 38-45页

作者： Ziyu Liao Bai Chen Dongming Bai jiajun xu Qian Zheng Keming Liu Hongtao Wu College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Mechanical and Electrical Engineering College of Jinhua Polytechnic Jinhua 321016China Key Laboratory of Crop Harvesting Equipment Technology of Zhejiang Province Jinhua 321016China

Surface electromyography(sEMG)control interface is a common method for human-centered *** have frequently improved the recognition accuracy of sEMG through multichannel or high-precision signal acquisition ***,this increases the cost and complexity of the control ***,this study developed a control interface based on the sEMG enveloped signal for a collaborative wearable robot to improve the accuracy of sEMG recognition based on the time-domain(TD)***,an acquisition device is developed to obtain the sEMG envelope signal,and 11 types of TD features are extracted from the sEMG envelope signal acquired from the upper ***,a dimension reduction method based on the correlation coefficient is proposed,transforming the 11-dimensional feature into a five-dimensional envelope feature set without decreasing the ***,a recognition algorithm based on a neural network has also been proposed for gesture ***,the recognition accuracy of the proposed method,principal component analysis(PCA)feature set,and Hudgins TD feature set is compared,with their accuracy at 84.39%,72.44%,and 70.89%,***,the results indicate that the envelope feature set performs better than the common gesture recognition method based on signal channel sEMG envelope signal.

关键词： Surface electromyography(sEMG) Gesture recognition Features extraction Wearable robot

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Development of Wheel-Legged Biped Robots:A Review

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Journal of Bionic Engineering 2024年第2期21卷 607-634页

作者： xuefei Liu Yi Sun Shikun Wen Kai Cao Qian Qi Xiaoshu Zhang Huan Shen Guangming Chen jiajun xu Aihong Ji Lab of Locomotion Bioinspiration and Intelligent Robots College of Mechanical and Electrical EngineeringNanjing University of Aeronautics and Astronautics29 Yudao StreetNanjing210016China State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

The wheel-legged biped robot is a typical ground-based mobile robot that can combine the high velocity and high efficiency pertaining to wheeled motion and the strong,obstacle-crossing performance associated with legged *** robots have gradually exhibited satisfactory application potential in various harsh scenarios such as rubble rescue,military operations,and wilderness ***-legged biped robots are divided into four categories according to the open–close chain structure forms and operation task modes,and the latest technology research status is summarized in this *** hardware control system,control method,and application are analyzed,and the dynamic balance control for the two-wheel,biomimetic jumping control for the legs and whole-body control for integrating the wheels and legs are *** summary,it is observed that the current research exhibits problems,such as the insufficient application of novel materials and a rigid–flexible coupling design;the limited application of the advanced,intelligent control methods;the inadequate understanding of the bionic jumping mechanisms in robot legs;and the insufficient coordination ability of the multi-modal motion,which do not exhibit practical application for the wheel-legged biped ***,this study discusses the key research directions and development trends for the wheel-legged biped robots.

关键词： Wheel-legged biped robot Wheeled motion Legged motion Control strategy

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The Time-frequency Characteristic of a Large Volume Airgun Source Wavelet and Its Influencing Factors

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Earthquake Research in China 2016年第3期30卷 364-379页

作者： Xia Ji Jin Xing Cai Huiteng xu jiajun Institute of Engineering Mechanics China Earthquake Administration Harbin 150080 China Key Laboratory of Earthquake Engineering and Engineering Vibration Institute of Engineering Mechanics CEA Harbin150080 China Earthquake Administration of Fujian Province Fuzhou 350003 China

Through analyzing the near-field hydrophone records of the airgun experiment in the Jiemian reservoir,Fujian,we study the time-frequency characteristic of airgun source wavelet and the influence of gun depth and firing pressure,and explain the process of bubble oscillation based on the Johnson( 1994) bubble model. The data analysis shows that:( 1) Airgun wavelet is composed of primary pulse and bubble pulse. The primary pulse,which is of large amplitude,short duration and wide frequency band,is usually used in shallow exploration. The bubble pulse,which is concentrated in the low-frequency range,is usually used in deep exploration with deep vertical penetration and far horizontal propagation.( 2) The variation of primary pulse amplitude with gun depth is very small,bubble pulse amplitude and the dominant frequency increase,and peak-bubble ratio and bubble period decrease. When the gun depth is 10 m,primary pulse amplitude and peakbubble ratio are maximum,which is suitable for shallow exploration; when gun depth is25 m,bubble pulse amplitude is large, and peak-bubble ratio is minimum, which is suitable for deep exploration.( 3) The primary pulse amplitude,bubble pulse amplitude,peak-bubble ratio,and bubble period increase and the dominant frequency decreases with increased firing pressure.

关键词： Airgun wavelet Time-frequency characteristic Wavelet parameters Gun depth Firing pressure

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