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Mobility Analysis of Altmann Overconstrained Linkages by Modified Grübler-Kutzbach Criterion

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 638-646页

作者： liu jingfang LI Yanwen HUANG Zhen College of Mechanical Engineering andApplied Electronics Technology Beijing University of Technology Beijing 100124 China Robotics Research Center Yanshan University Qinhuangdao 066004 China

Developing a general mobility method/formula is a hot topic lasting for more than 150 years in kinematics. It is necessary to apply any mobility method to puzzling overconstrained mechanisms for verification of its generality. Altmann linkages are such recognized puzzling mechanisms that their mobility analysis is of important significance. A necessary condition for judging a general mobility method is that the method can be fit for Altmann linkages. Firstly, this study classes Altmann linkages into 17 types in terms of the numbers and types of kinematic pairs, and then Altmann overconstrained linkages are further classified into 4 types. Secondly, the mobility of Altmann overconstrained linkages is systematically analyzed by the Modified Grübler-Kutzbach criterion based on screw theory, where passive freedoms are defined as limb passive freedoms and mechanism passive freedoms. In addition, the full-cycle mobility is judged, which overcomes the shortcoming of instantaneous property of screw theory. It is shown that Modified Grübler-Kutzbach criterion not only obtains the correct numerical mobility, but also gives the mobility character by resolving reciprocal screws for the constraint system. This study lays the foundation of verification for the generality of Modified Grübler-Kutzbach criterion. Besides, Altmann overconstrained linkages almost comprise all kinds of modern parallel mechanisms and some classical mechanisms, which provides an important reference for mechanism mobility calculation.

关键词： mobility analysis overconstrained linkage screw theory

Mobility of the Myard 5R Linkage Involved in “Gogu Problem”

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Chinese Journal of Mechanical Engineering 2009年第3期22卷 325-330页

作者： liu jingfang HUANG Zhen LI Yanwen Robotics Research Center Yanshan Univers#y Qinhuangdao 066004 China

Since the traditional Griibler-Kutzbach criterion fails in many overconstrained mechanisms, developing a general mobility formula is a hot topic lasting for more than 150 years in mechanisms. GOGU systematically investigated various mobility methods, and pointed that the methods were not fit for two kinds of paradoxical overconstrained mechanisms. The mobility on the two kinds of mechanisms is regarded as ＂Gogu problem＂. The Modified Griibler-Kutzbach criterion has solved the mobility of the second kind of mechanisms in ＂Gogu problem＂, and has developed into a systematic mobility methodology. Myard 5R linkage is one of the single-loop mechanisms involved in ＂Gogu problem＂, its joint axes are distributed in space with special geometric conditions, which increases the difficulty of mobility analysis. The study is to calculate the global mobility of the Myard 5R linkage using the mobility methodology. Firstly, the mobility methodology based on screw theory is briefly introduced. Secondly, some homogeneous transforms are performed according to the D-H parameters and the invariance of the linkage plane symmetry is revealed, which provides an idea to judge a plane-symmetric loop. The special geometric features of the axes distribution are discussed as well. Finally, the global mobility of the Myard 5R linkage is determined by the Modified Grubler-Kutzbach criterion. The results show that the methodology can be applied to more paradoxical mechanisms.

关键词： overconstrained linkage screw theory mobility

Dynamic Modeling and Experimental Verification of an RPR Type Compliant Paralle Mechanism with Low Orders

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 83-94页

作者： Shuang Zhang jingfang liu Huafeng Ding Yanbin Zhang School of Mechatronics Engineering Henan University of Science and TechnologyLuoyangHenanChina Faculty of Materials and Manufacturing College of Mechanical Engineering and Applied Electronics TechnologyBeijing University of TechnologyBeijingChina Key laboratory of advanced manufacturing technology Beijing University of TechnologyBeijingChina School of Mechanical Engineering and Electronic Information China University of Geosciences(Wuhan)WuhanChina Center of Machinery Equipment Advanced Manufacturing of Henan Province LuoyangChina

Efficiency of calculating a dynamic response is an important point of the compliant mechanism for posture *** modeling with low orders of a 2R1T compliant parallel mechanism is studied in the *** mechanism with two out-of-plane rotational and one lifting degrees of freedom(DoFs)plays an important role in posture *** on elastic beam theory,the stiffness matrix and mass matrix of the beam element are established where the moment of inertia is *** improve solving efficiency,a dynamic model with low orders of the mechanism is established based on a modified modal synthesis ***,each branch of the RPR type mechanism is divided into a ***,a set of hypothetical modes of each substructure is obtained based on the C-B ***,dynamic equation of the whole mechanism is established by the substructure assembly.A dynamic experiment is conducted to verify the dynamic characteristics of the compliant mechanism.

关键词： Compliant parallel mechanism Dynamic model Modal synthesis method Dynamic experiment

A general methodology for mobility analysis of mechanisms based on constraint screw theory

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Science China(Technological Sciences) 2009年第5期52卷 1337-1347页

作者： Zhen Huang jingfang liu DaXing Zeng Robotics Research Center Yanshan University Qinhuangdao 066004 China

It is well known that the traditional Grübler-Kutzbach formula fails to calculate the mobility of some classical mechanisms or many modern parallel robots,and this situation seriously hampers mechani-cal *** seek an efficient and universal method for mobility calculation has been a heated topic in the sphere of *** modified Grübler-Kutzbach criterion proposed by us achieved success in calculating the mobility of a lot of highly complicated mechanisms,especially the mobility of all recent parallel mechanisms listed by Gogu,and the Bennett mechanism known for its particular *** wide applications of the criterion,a systematic methodology has recently *** paper systematically presents the methodology based on the screw theory for the first time and ana-lyzes six representative puzzling *** addition,the methodology is convenient for judgment of the instantaneous or full-cycle mobility,and has become an effective and general method of great scientific value and practical *** the first half,this paper introduces the basic screw theory,then it presents the effective methodology formed within this *** second half of this paper presents how to apply the methodology by analyzing the mobility of several puzzling ***,this paper contrasts and analyzes some different methods and interprets the essential reason for validity of our methodology.

关键词： mobility analysis redundant constraint parallel mechanism

Applicability and Generality of the Modified Grübler-Kutzbach Criterion

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Chinese Journal of Mechanical Engineering 2013年第2期26卷 257-263页

作者： LI Yanwen WANG Lumin liu jingfang HUANG Zhen Hebei Provincial Key Laboratory of Parallel Robot and Mechatronic System Yanshan University College of Environment and Chemical Engineering Yanshan University College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology

A generally applicable criterion for all mechanism mobility has been an active domain in mechanism theory lasting more than 150 years. It is stated that the Modified Grübler-Kutzbach criterion for mobility has been successfully used to solve the mobility of many more kinds of mechanisms, but never before has anyone proven the applicability and generality of the Modified Grübler-Kutzbach criterion in theory. In order to fill the gap, the applicability and generality of the Modified Grübler-Kutzbach Criterion of mechanism mobility is systematically demonstrated. Firstly, the mobility research background and the Modified Grübler-Kutzbach criterion are introduced. Secondly, some new definitions, such as half local freedom, non-common constraint space of a mechanism and common motion space of a mechanism, etc, are given to demonstrate the correctness and broad applicability of the Modified Grübler-Kutzbach criterion. Thirdly, the general applicability of the Modified Grübler-Kutzbach criterion is demonstrated based on screw theory. The mobilities of the classical DELASSUS mechanisms and a modern planar parallel mechanism, are determined through the Modified Grübler-Kutzbach criterion, which are as examples to show the practical application of the Modified Grübler-Kutzbach criterion.

关键词： mobility screw theory classical mechanism parallel mechanism

General Order Principle for Multi-Bennett Linkages

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Chinese Journal of Mechanical Engineering 2013年第2期26卷 275-281页

作者： liu jingfang YU Yueqing HUANG Zhen HUANG Xiao'ou College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology Robotics Research Center Yanshan University

Order analysis for multi-Bennett linkages is a difficult topic in kinematics. Traditional methods fail to obtain the order of multi-Bennett linkages due to considering the special geometric distributions among joint axes. An order principle for multi-Bennett linkages is presented. For a summated multi-Bennett linkage, three procedures are included in the order principle. Firstly, a homogeneous screw equation is obtained by taking linear superposition operations and then the maximum order is determined according to linear dependency of all screws. Secondly, two theorems are employed to determine the maximum order, where the first is used to judge the linear independency of four-system screws and the second is fit for identifying the linear independency of five-system screws. Lastly, all possible cases in the order range are considered until the valid order is screened out. For a syncopated multi-Bennett linkage, an equivalent summated model is built and then the order analysis is the same as that of summated linkages. In order to verify the effectiveness of the presented order principle, the orders of summated 5R and 6R linkages as well as a syncopated 6R linkage are analyzed. The computed orders of the former two summated linkages are both 4 and the computed order of the last syncopated 6R linkage is 5. The results coincide with the prototype data. The advantage of the proposed principle is that it can get the correct order of a multi-Bennett linkage without solving the geometric conditions of joint axes and has wide application in variety of multi-Bennett linkages.

关键词： Order analysis Multi-Bennett linkage Homogeneous screw equation Screw theory

Genome-Wide Analysis of Gene Expression in Stationary Phase and Genetic Characterization of Stationary-Phase-Dependent Halocin Gene Expression in the Haloarchaeon Haloferax mediterranei

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Journal of Genetics and Genomics 2013年第8期40卷 441-444页

作者： Xiaoqing liu Lei Wang jingfang liu Lei Cai Hua Xiang State Key Laboratory of Microbial Resources Institute of MicrobiologyChinese Academy of Sciences University of Chinese Academy of Sciences

The stationary phase of microbial growth is a very complex state regulated by various environmental and physiological factors. An intensive study of stationary phase could promote a comprehensive understanding of the complete life cycle of microorganisms, and may provide important insights into their adaptation to harsh and nutrient-depleted conditions. Although the underlying mechanisms have been weU-studied in bacteria and yeasts （Herman, 2002; Navarro Llorens et al., 2010）, less is known about this growth phase in archaea yet. The haloarchaeon Haloferax mediterranei has served as a good model for studying haloarchaeal physiology and metabolism for several decades because of its accelerated growth, remarkable metabolic ability and genomic stability （Han et al., 2012）. During stationary phase, H. mediterranei can produce halocin H4 （Cheung et al.,

关键词： Genome-Wide Analysis of Gene Expression in Stationary Phase and Genetic Characterization of Stationary-Phase-Dependent Halocin Gene Expression in the Haloarchaeon Haloferax mediterranei KEGG BRE gene down

Study on the hepatoprotective effect of Sporidiobolus pararoseus polysaccharides under the“gut microbiome-amino acids metabolism”network

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Food Bioscience 2022年第5期49卷 1318-1326页

作者： Chang liu Hanyi Hua Yahui Guo He Qian jingfang liu Yuliang Cheng State Key Laboratory of Food Science and Technology Jiangnan UniversityNo.1800 Lihu AvenueWuxiJiangsu Province214122China Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province Jiangnan UniversityNo.1800 Lihu AvenueWuxiJiangsu Province214122China Institutional Center for Shared Technologies and Facilities of Institute of Microbiology Chinese Academy of SciencesNO.1 Beichen West RoadChaoyang DistrictBeijing100101China

The“gut-liver”axis plays an important role in the mechanism of alcoholic liver disease(ALD).Sporidiobolus pararoseus polysaccharides(SPP)have been shown to improve the gut barrier and liver damage in mice with ***,the process is modulated via the gut microbiome and amino acids in the gut-liver axis has not been *** this study,the gut microbiome and metabolic function were explored for the mechanism by which SPP improve *** results showed that after the SPP were metabolized by ALD mice,microbial diversity was altered,and the relative abundances of Lachnospiraceae,Alistipes,Eubacterium siraeum,and Bacteroides *** predicted results of microbiome functions promoted the biosynthesis of amino acids,tyrosine,tryptophan,valine,leucine,and isoleucine were *** results also confirmed that butanoate metabolism and biosynthesis of phenylalanine,tyrosine,and tryptophan are the main regulatory pathways of *** gut microbiome metabolizes the hallmark metabolites of SPP were L-tyrosine,L-histidine,and *** analysis and interaction network deeply mine gut microbiome(Lachnospiraceae,Eubacterium siraeum,Erysipelotrichaceae),metabolites(L􀀀serine,L􀀀tyrosine),and metabolism(biosynthesis of amino acids,valine,leucine,and isoleucine biosynthesis)may be key factors in the SPP-gut microbiome-metabolites-metabolism in ALD ***,SPP have the effect of proliferating beneficial gut microbiome that metabolize polysaccharides,promoting the production of amino acids,and regulating liver metabolic disorders.

关键词： Sporidiobolus pararoseus polysaccharides Gut microbiome Amino acids metabolism Bioinformatics

Change of Disease Spectrum Characteristics of Psychiatric Inpatients Before and After Lockdown Lifted During the COVID-19 Pandemic—Wuhan City,Hubei Province,China,2021

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China CDC weekly 2022年第18期4卷 389-392,I0002-I0004页

作者： jingfang liu Xuan Gong Xiaofen Li Zhiying Wan Hongqiang Sun Lijun Kang Zhongchun liu Department of Psychiatry Renmin Hospital of Wuhan UniversityWuhan CityHubei ProvinceChina Peking University Sixth Hospital Peking University Institute of Mental HealthNHC Key Laboratory of Mental Health(Peking University)National Clinical Research Center for Mental Disorders(Peking University Sixth Hospital)National Center for Mental HealthChinese Center for Disease Control and PreventionBeijingChina

Summary What is already known about this topic?The coronavirus disease 2019(COVID-19)pandemic poses a significant threat to mental health globally and may change the proportion of hospitalized *** is added by this report?This report analyzed and compared the disease characteristics of psychiatric inpatients one year before and after Wuhan lifted lockdown during *** 50%of the inpatients were diagnosed with bipolar disorder;females and adolescents had a higher prevalence of mental *** are the implications for public health practice?More attention should be paid to the mental health of children,adolescents,and females.

关键词： Wuhan globally COV