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Type Synthesis of Lower Mobility Parallel Mechanisms: A Review

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Chinese Journal of Mechanical Engineering 2019年第2期32卷 13-23页

作者： Wei Ye qinchuan Li Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech University

Type synthesis of mechanisms aims to systematically determine all possible structures for a specific mobility requirement. Numerous methods based on di erent theories were proposed for type synthesis of lower mobility parallel mechanisms in past decades. However, there does not exist a comprehensive review on these approaches. Therefore, the goal of this paper is to give such a review, classifying the approaches proposed in the literature into three groups, namely, motion-based methods, constraint-based methods, and other methods. The motion-based methods include the Lie group based method, the GF set method, the linear transformation method, the POC set method,and the finite screw method. The constraint-based methods involve the screw theory-based method, the virtual chain method, the method based on Grassmann line geometry and line graphs, and the motion constraint generator method. Other methods contain the enumeration approach based on the general CGK mobility formula and the graph theory method. Upon thoroughly analyzing the characteristics and/or limitations of each method, this review provides a well reference to help researchers find an e ective synthesis method for innovative design and further scientific investigations for mechanisms.

关键词： Parallel mechanism Lower mobility Type synthesis Innovative design

Robotized manufacturing equipment:A review from the perspective of mechanism topology

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Science China(Technological Sciences) 2023年第6期66卷 1683-1697页

作者： YE Wei TANG TengFei LI qinchuan National and Local Joint Engineering Research Center of Reliability Analysis and Testing for Mechanical and Electrical Products Zhejiang Sci-Tech UniversityHangzhou 310018China School of Mechanical Engineering Zhejiang Sci-Tech UniversityHangzhou 310018China

In recent years,robots have been extensively applied in the establishment of intelligent manufacturing *** robotized manufacturing equipment have been developed,some of which have gained successful applications.A mechanism is the skeleton of a machine that transfers motion and *** topology of a mechanism is an important gene that determines the function and performance of a *** several reviews have focused on robotized manufacturing,an up-to-date review of robotized manufacturing equipment from the perspective of mechanism topology is *** motivated us to present a survey about existing robotics structures used in manufacturing *** studies are classified into three types:serial robot-based manufacturing equipment,parallel kinematic machines,and hybrid robot-based manufacturing *** features and performance behaviour of these equipments,as determined by their mechanism topology,are *** particular,the influences of joint numbers,rotational axes of output motion,actuation schemes,and topological symmetry on equipment performance are discussed to provide insight into the new development of robotized manufacturing equipment,as well as future research directions on this topic.

关键词： intelligent manufacturing robotized manufacturing equipment mechanism topology performance

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Effects of PyC shell thickness on the microstructure,ablation resistance of SiCnws/PyC-C/C-ZrC-SiC composites

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Journal of Materials Science & Technology 2021年第12期71卷 55-66页

作者： qinchuan He Hejun Li Xuemin Yin Jinhua Lu College of Materials and Chemistry&Chemical Engineering Chengdu University of TechnologyChengdu 610059China Carbon/Carbon Composites Research Center Northwestern Polytechnical UniversityXi’an710072China

SiC nanowires/pyrocarbon(SiCnws/PyC)core-shell structure toughenedC/C-ZrC-SiC composites were fabricated by CLVD process,and the influences of PyC shell thickness on the microstructure and ablation resistance of the composites were *** results presented that SiCnws/PyC core-shell structure had a linear shape,and the composites became dense with the increasing PyC *** the thickness of PyC shell increased from 0 to 2.4μm,the density and thermal conductivity of the composites was improved gradually,but the coefficient of thermal expansion(CTE)decreased firstly and then *** the ablation test for 90 s,the ablation rates of the composites decreased continuously as the PyC thickness increased from 0 to 1.4μm,but increased when the PyC thickness was up to 2.4μ*** when the PyC thickness was 1.4μm,the linear and mass ablation rates of the composites were 71.25%and 63.01%lower than those of the composites without PyC *** reasons behind the remarkable improvement of anti-ablation property were that the proper PyC thickness could alleviate the CTE mismatch to promote the formation of complete oxide coating,improve the thermal conductivity to reduce heat corrosion and enhance the capability to limit the mechanical erosion.

关键词： SiCnws/PyC core-shell structure C/C-ZrC-SiC composites Microstructure Ablation resistance CLVD

Displacement manifold method for type synthesis of lower-mobility parallel mechanisms

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Science China(Technological Sciences) 2004年第6期47卷 641-650页

作者： LI qinchuan HUANG Zhen Jacques Marie Hervé Center of Integration Engineering Zhejiang University of SciencesHangzhou 310033China Robotics Research Center Yanshan UniversityQinhuangdao 066004China Ecole Centrale Paris France

Type synthesis of lower-mobility parallel mechanisms is a hot and frontier topic in international academic and industrial field. Based on the Lie group theory, a displacement manifold synthesis method is proposed. For all the nine kinds of lower-mobility parallel mechanisms, the mechanism displacement manifold, limb displacement manifold and the geometrical conditions which guarantee that the intersection of the limb displacement manifold is the desired mechanism displacement manifold are enumerated. Various limb kinematic chains can be obtained using the product closure of displacement subgroup. Parallel mechanisms can be constructed with these limbs while obeying the geometrical conditions. Hence, all the nine kinds of lower-mobility parallel mechanisms can be synthesized using this method. Since displacement manifold deals with finite motion, the result mechanism of synthesis have full-cycle mobility. Novel architectures of lower-mobility parallel mechanisms can be obtained using this method.

关键词： lower-mobility parallel mechanisms Lie group displacement manifold type synthesis

New Family of RPR-Equivalent Parallel Mechanisms:Design and Application

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Chinese Journal of Mechanical Engineering 2017年第2期30卷 217-221页

作者： qinchuan LI Lingmin XU Qiaohong CHEN Wei YE Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China School of Information Zhejiang Sci-Tech UniversityHangzhou 310018China

Parallel mechanisms（PMs） have been used as skeletons or end-effectors in various advanced manufacturing equipment. Compared with their serial counterparts, PMs offer high rigidity, good dynamic response, and large p... 详细信息

关键词： PM RPR

Efficient microwave absorption achieved through in situ construction of core-shell Co Fe_(2)O_(4)@mesoporous carbon hollow spheres

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International Journal of Minerals,Metallurgy and Materials 2023年第3期30卷 504-514页

作者： Lianggui Ren Yiqun Wang Xin Zhang qinchuan He Guanglei Wu College of Materials and Chemistry&Chemical Engineering Chengdu University of TechnologyChengdu 610059China Institute of Materials for Energy and Environment State Key Laboratory of Bio-fibers and Eco-textilesCollege of Materials Science and EngineeringQingdao UniversityQingdao 266071China

Cobalt ferrite(CoFe_(2)O_(4)),with good chemical stability and magnetic loss,can be used to prepare composites with a unique structure and high *** this study,CoFe_(2)O_(4)@mesoporous carbon hollow spheres(MCHS)with a core-shell structure were prepared by introducing CoFe_(2)O_(4)magnetic particles into hollow mesoporous carbon through a simple in situ ***,the microwave absorption performance of the CoFe_(2)O_(4)@MCHS composites was *** and dielectric losses can be effectively coordinated by constructing the porous structure and adjusting the ratio of MCHS and CoFe_(2)O_(4).Results show that the impedance matching and absorption properties of the Co Fe_(2)O_(4)@MCHS composites can be altered by tweaking the mass ratio of MCHS and CoFe_(2)O_(4).The minimum reflection loss of the Co Fe_(2)O_(4)@MCHS composites reaches-29.7 dB at 5.8 *** addition,the effective absorption bandwidth is 3.7 GHz,with the thickness being 2.5 *** boosted microwave absorption can be ascribed to the porous core-shell structure and introduction of magnetic *** coordination between the microporous morphology and the core-shell structure is conducive to improving the attenuation coefficient and achieving good impedance *** porous core-shell structure provides large solid-void and CoFe_(2)O_(4)-C interfaces to induce interfacial polarization and extend the electromagnetic waves’multiple scattering and ***,natural resonance,exchange resonance,and eddy current loss work together for the magnetic *** method provides a practical solution to prepare core-shell structure microwave absorbents.

关键词： porous core-shell structure microwave absorption interface polarization ferrite structure-controllable

Extraction of Astaxanthin from Euphausia pacific Using Subcritical 1,1,1,2-tetrafluoroethane

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Journal of Ocean University of China 2012年第4期11卷 562-568页

作者： HAN Yuqian MA qinchuan WANG Lan XUE Changhu Department of Food Science and Engineering Ocean University of ChinaQingdao 266003P.R.China

Euphausia pacific is an important source of natural astaxanthin. Studies were carried out to assess the extractability of astaxanthin from E. pacific using subcritical 1, 1, 1,2-tetrafluoroethane （R134a）. To examine the effects of multiple process variables on the extraction yield, astaxanthin was extracted under various conditions of pressure （30-150bar）, temperature （303-343 K）, time （10-50rain）, flow rate （2-10gmin-1）, moisture content （5.5%-63.61%）, and particle size （0.25-0.109mm）. The results showed that the extraction yield increased with temperature, pressure, time and flow rate, but decreased with moisture content and particle size. A maximum yield of 87.74% was obtained under conditions of 100bar, 333K, and 30min with a flow rate of 6gmin-1 and a moisture content of 5.5%. The substantial astaxanthin yield obtained under low-pressure conditions demonstrates that subcritical R134a is a good alternative to CO2 for extraction of astaxanthin from E. pacific.

关键词： subcritical R134a astaxanthin extraction Euphausia pacific

Singularity Analysis of a 3-RPS Parallel Manipulator Using Geometric Algebra

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Chinese Journal of Mechanical Engineering 2015年第6期28卷 1204-1212页

作者： LI qinchuan XIANG Ji'nan CHAI Xinxue WU Chuanyu Mechatronic Institute Zhejiang Sci-Tech University

Singular configurations must be avoided in path planning and control of a parallel manipulator. However, most studies rarely focus on an overall singularity loci distribution of lower-mobility parallel mechanisms. Geometric algebra is employed in analysis of singularity of a 3-RPS parallel manipulator. Twist and wrench in screw theory are represented in geometric algebra. Linear dependency of twists and wrenches are described by outer product in geometric algebra. Reciprocity between twists and constraint wrenches are reflected by duality. To compute the positions of the three spherical joints of the 3-RPS parallel manipulator, Tilt-and-Torsion angles are used to describe the orientation of the moving platform. The outer product of twists and constraint wrenches is used as an index for closeness to singularity（ICS） of the 3-RPS parallel manipulator. An overall and thorough perspective of the singularity loci distribution of the 3-RPS parallel manipulator is disclosed, which is helpful to design, trajectory planning and control of this kind of parallel manipulator.

关键词： singularity parallel manipulator geometric algebra

A Comparative Study on Kinematic Calibration for a 3-DOF Parallel Manipulator Using the Complete-Minimal,Inverse-Kinematic and Geometric-Constraint Error Models

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Chinese Journal of Mechanical Engineering 2023年第5期36卷 206-230页

作者： Haiyu Wu Lingyu Kong qinchuan Li Hao Wang Genliang Chen State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Intelligent Robot Research Center Zhejiang LabHangzhou 311100China School of Mechanical Engineering Zhejiang Sci-Tech UniversityHangzhou 310018China

Kinematic calibration is a reliable way to improve the accuracy of parallel manipulators, while the error model dramatically afects the accuracy, reliability, and stability of identifcation results. In this paper, a comparison study on kinematic calibration for a 3-DOF parallel manipulator with three error models is presented to investigate the relative merits of diferent error modeling methods. The study takes into consideration the inverse-kinematic error model, which ignores all passive joint errors, the geometric-constraint error model, which is derived by special geometric constraints of the studied RPR-equivalent parallel manipulator, and the complete-minimal error model, which meets the complete, minimal, and continuous criteria. This comparison focuses on aspects such as modeling complexity, identifcation accuracy, the impact of noise uncertainty, and parameter identifability. To facilitate a more intuitive comparison, simulations are conducted to draw conclusions in certain aspects, including accuracy, the infuence of the S joint, identifcation with noises, and sensitivity indices. The simulations indicate that the complete-minimal error model exhibits the lowest residual values, and all error models demonstrate stability considering noises. Hereafter, an experiment is conducted on a prototype using a laser tracker, providing further insights into the diferences among the three error models. The results show that the residual errors of this machine tool are signifcantly improved according to the identifed parameters, and the complete-minimal error model can approach the measurements by nearly 90% compared to the inverse-kinematic error model. The fndings pertaining to the model process, complexity, and limitations are also instructive for other parallel manipulators.

关键词： Kinematic calibration Parallel manipulator Error modeling Product of exponential(POE)