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Design of a Two-Step Calibration Method of Kinematic Parameters for Serial Robots

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Chinese Journal of Mechanical Engineering 2017年第2期30卷 438-448页

作者： Wei WANG Lei WANG chao yun School of Mechanical Engineering and Automation Beihang University State Key Lab of Digital Manufacturing Equipment and Technology Huazhong University of Science and Technology

Serial robots are used to handle workpieces with large dimensions, and calibrating kinematic parameters is one of the most efficient ways to upgrade their accuracy. Many models are set up to investigate how many kinematic parameters can be identified to meet the minimal principle, but the base frame and the kinematic parameter are indistinctly calibrated in a one-step way. A two-step method of calibrating kinematic parameters is proposed to improve the accuracy of the robot＇s base frame and kinematic parameters. The forward kinematics described with respect to the measuring coordinate frame are established based on the product- of-exponential （POE） formula. In the first step the robot＇s base coordinate frame is calibrated by the unit quaternion form. The errors of both the robot＇s reference configuration and the base coordinate frame＇s pose are equivalently transformed to the zero-position errors of the robot＇s joints. The simplified model of the robot＇s positioning error is established in second-power explicit expressions. Then the identification model is finished by the least square method, requiring measuring position coordinates only. The complete subtasks of calibrating the robot＇ s 39 kinematic parameters are finished in the second step. It＇s proved by a group of calibration experiments that by the proposed two-step calibration method the average absolute accuracy of industrial robots is updated to 0.23 mm. This paper presents that the robot＇s base frame should be calibrated before its kinematic parameters in order to upgrade its absolute positioning accuracy.

关键词： Kinematic parameter Calibration Error model Product of exponential Industrial robot

COUPLING EFFECT OF FLEXIBLE JOINT AND FLEXIBLE LINK ON DYNAMIC SINGULARITY OF FLEXIBLE MANIPULATOR

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Chinese Journal of Mechanical Engineering 2008年第1期21卷 9-12页

作者： GAO Zhihui yun chao BIAN Yushu School of Mechanical Engineering and Automation Beihang University Beijing 100083 China

The coupling effect of the flexible joint and the flexible link on the dynamic singularity of the flexible manipulator is addressed. Firstly, the dynamic equations of a flexible manipulator with a flexible joint and a flexible link are derived. Secondly, the relationship and property between the flexible joint and the flexible link are analyzed. It shows that the flexible joint＇s amplitude will increase abruptly, thereby the dynamic singularity occurs if the frequency of a flexible joint is near or equal to some natural frequency of a flexible link. Finally, some numerical simulations which will verify the correctness of the theoretical analysis, are carded out. The results are fundamental for the design of a flexible manipulator and for the avoidance of the dynamic singularity.

关键词： Dynamic singularity Resonance Natural frequency Flexible manipulator

OPTIMAL CONTROL OF THE FLEXI-BLE LINK MANIPULATOR WITH CONTROLLABLE LOCAL DEGREES OF FREEDOM

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Chinese Journal of Mechanical Engineering 2008年第4期21卷 27-30页

作者： BIAN Yushu yun chao GAO Zhihui School of Mechanical Engineering and Automation Beihang Universily Beijing 100083 China State Key Laboratory for Manufacturing Systems Engineering Xi＇an Jiaotong University Xi＇an 710049 China School of Mechanical Engineering and Automation Beihang University Beijing 100083 China

Although flexible manipulators own many potential advantages, one of their major disadvantages is the deterioration of the end-effector accuracy due to the flexibility. Therefore, how to reduce vibration is a significant problem. Inspired by the observation on the motion behaviors of animals, a new idea of decreasing motion deflection of the flexible manipulator is suggested. The concept of controllable local degrees of freedom is proposed and analyzed. By way of optimizing local motion provided by the controllable local degrees of freedom, the end-effector deflection of the flexible manipulator can be effectively decreased through dynamic coupling. The corresponding optimal method for vibration control of the flexible manipulator is put forward. The kinematic simulation is carried ant on a three-link flexible manipulator The corresponding results verify the feasibility of this method.

关键词： Flexible manipulator Vibration Flexibility Local degree of freedom

Synthesis of Calix[4]resorcinarene Core Dendrimers with Peripheral Salicylideneimine Functional Groups

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Chemical Research in Chinese Universities 2006年第4期22卷 537-542页

作者： HAN Jun GE yun YAN chao-guo College of Chemistry ＆ Chemical Engineering Yangzhou University Yangzhou 225002 P. R. China

First to third-generation calix[4] resorcinarene core dendrimers, compounds 4a, 4b, 7a, 7b, 10a and 10b, were prepared via the divergent method in seven steps with the corresponding tetraphenyl- and tetra （hydroxyphenyl） calix[4] resorcinarenes （compounds 1a, 1b） as the starting material. The repeat units of the polyamidoamines of these dendrimers were obtained by the ammonolysis of ethyl calixarylacetates 2a and 2b with 1,3-diaminopropane, that is, amide derivatives with terminal amino groups, which in turn reacted with ethyl acrylate to give a higher generation of ester derivatives. The structures of these dendrimers were characterized by IR, ^1H and ^13C NMR spoctrometries. The crystal structure of compound 2b with 12 ethoxycarbonylmethoxy groups was determined by X-ray analysis.

关键词： Calixresorcinarene Dendrimer Schiffbase Amide Calixarene

3.1 μm mid-infrared luminescence in Er^(3+) doped ZnF_(2) modified aluminum fluoride glass

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Journal of Rare Earths 2023年第7期41卷 997-1003,I0002页

作者： Chuncheng Zhang chaomin Zhang chao yun Shengying Lai School of Materials Engineering Shanghai University of Engineering ScienceShanghai 201620China School of Mathematics Physics and StatisticsShanghai University of Engineering ScienceShanghai 201620China

Herein,melt-quenching and Er^(3+) doping were used to synthesize fluoride glass specimens with low phonon energies(582 cm^(-1)).These glass specimens exhibit intense 3.1 μm mid-infrared band emission when they are excited by a 980 nm laser diode,achieving a full width at half maximum(FWHM) of about166 *** 3.1 μm emission intensity is enhanced by the introduction of ZnF_(2) to the AlF_(3)-based fluoride ***-conversion emission,strong near-infrared emission,and fluorescence lifetime are enhanced to different degrees by increasing the ZnF_(2) ***,the spectroscopic characteristics of the glass specimens and the highly efficient Er^(3+):~4S_(3/2)→~4F_(9/2) transition's energy transfer mechanism were *** absorption spectra and emission spectra of these aluminum fluoride glass specimens were used to calculate their gain coefficients and maximum cross sections at 1.5 and 3.1 μ***,the spectral properties of these prepared aluminum fluoride glass specimens demonstrate their high potential for use as infrared laser host materials.

关键词： 3.1μm mid-infrared luminescence Energy transfer Er^(3+)ions Spectroscopic properties Rare earths

The Stability of the Elliptic Equilibrium of Planar Quasi-periodic Hamiltonian Systems

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Acta Mathematica Sinica,English Series 2012年第4期28卷 801-816页

作者： yun chao WU Yi Qian WANG Department of Mathematics Nanjing University

In this paper, we study the planar Hamiltonian systemwhere where f is real analytic in x and θ,A（θ） is a 2×2real analytic symmetric matrix,J=（1^-1） and w is a Diophantine vector. Under the assumption that the unperturbed systemreducible and stable, we obtain a series of criteria for the stability and instability of the equilibrium of the perturbed system.

关键词： Lyapunov stability elliptic equilibrium Hamiltonian system quasi-periodic system

Designing and Optimization of an Off-line Programming System for Robotic Belt Grinding Process

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 647-655页

作者： WANG Wei yun chao ZHANG Ling GAO Zhihui Robotics Institute Beihang University Beijing 100191 China State Key Laboratory for Manufacturing Systems Engineering Xi＇an Jiaotong University Xi＇an 710049 China

Off-line programming （OLP） system becomes one of the most important programming modules for the robotic belt grinding process, however there lacks research on increasing the grinding dexterous space depending on the OLP system. A new type of grinding robot and a novel robotic belt grinding workcell are forwarded, and their features are briefly introduced. An open and object-oriented off-line programming system is developed for this robotic belt grinding system. The parameters of the trimmed surface are read from the initial graphics exchange specification （IGES） file of the CAD model of the workpiece. The deBoor-Cox basis function is used to sample the grinding target with local contact frame on the workpiece. The numerical formula of inverse kinematics is set up based on Newton＇s iterative procedure, to calculate the grinding robot configurations corresponding to the grinding targets. After the grinding path is obtained, the OLP system turns to be more effective than the teach-by-showing system. In order to improve the grinding workspace, an optimization algorithm for dynamic tool frame is proposed and performed on the special robotic belt grinding system. The initial tool frame and the interval of neighboring tool frames are defined as the preparation of the algorithm. An optimized tool local frame can be selected to grind the complex surface for a maximum dexterity index of the robot. Under the optimization algorithm, a simulation of grinding a vane is included and comparison of grinding workspace is done before and after the tool frame optimization. By the algorithm, the grinding workspace can be enlarged. Moreover the dynamic tool frame can be considered to add one degree-of-freedom to the grinding kinematical chain, which provides the theoretical support for the improvement of robotic dexterity for the complex surface grinding.

关键词： off-line programming robotic belt grinding path generation tool optimization

Vascular Metabolic Mechanisms of Pulmonary Hypertension

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Current Medical Science 2020年第3期40卷 444-454页

作者： Xiao-fan SHI yun-chao SU Department of Pharmacology&Toxicology Augusta UniversityAugustaGA30912USA Department of Medicine Augusta UniversityAugustaGA30912USA Vascular Biology Center Medical College of GeorgiaAugusta UniversityAugustaGA 30912USA

Pulmonary hypertension(PH)is a severe and progressive disease characterized by increased pulmonary vascular resistance leading to right heart failure and *** PH,the cellular metabolisms including those of the three major nutrients(carbohydrate,lipid and protein)are aberrant in pulmonary vascular *** uptake,glycolysis,insulin resistance,sphingolipid S1P,PGE2,TXA2,leukotrienes and glutaminolysis are upregulated,and phospholipid-prostacyclin and L-arginine-nitric oxide pathway are compromised in lung vascular *** acid metabolism is disordered in lung endothelial cells and smooth muscle *** molecular mechanisms are integrated to promote PH-specific abnormal vascular cell proliferation and vascular *** review summarizes the recent advances in the metabolic reprogramming of glucose,fatty acid,and amino acid metabolism in pulmonary vascular remodeling in PH and the mechanisms for how these alterations affect vascular cell fate and impact the course of PH.

关键词： pulmonary hypertension metabolism vascular remodeling proliferation

High Yield Transfer of Clean Large-Area Epitaxial Oxide Thin Films

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Nano-Micro Letters 2021年第2期13卷 363-376页

作者： Bowen Zhang chao yun Judith L.MacManus-Driscoll Department of Materials Science and Metallurgy University of Cambridge27 Charles Babbage RoadCambridge CB30FSUK

In this work,we have developed a new method for manipulating and transferring up to 5 mm×10 mm epitaxial oxide thin *** method involves fixing a PET frame onto a PMMA attachment film,enabling transfer of epitaxial films lifted-off by wet chemical etching of a Sr3Al2O6 sacrificial *** crystallinity,surface morphology,continuity,and purity of the films are all preserved in the transfer *** demonstrate the applicability of our method for three different film compositions and structures of thickness~100 ***,we show that by using epitaxial nanocomposite films,lift-off yield is improved by~50% compared to plain epitaxial films and we ascribe this effect to the higher fracture toughness of the *** work shows important steps towards large-scale perovskite thin-film-based electronic device applications.

关键词： Free-standing oxide thin films High yield transfer Wet etching Crack prevention