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Type synthesis of the rotational decoupled parallel mechanism based on screw theory

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Science China(Technological Sciences) 2011年第4期54卷 998-1004页

作者： ZENG DaXing huang zhen College of Mechanical Engineering Yanshan UniversityQinhuangdao 066004China

With the gradual deepening of study on the parallel mechanism,the difficulty brought by the existence of coupling to the theoretical analysis and practical application of parallel mechanisms is becoming increasingly *** research on the decoupled parallel mechanism is currently one of the hot *** most of the rotational parallel mechanisms,which has been widely used in spatial orientation fields,are not *** is comparative difficult for the synthesis of fully decoupled rotational parallel mechanisms,and the number of the existing parallel mechanisms which can realize rotational decoupling is *** addition,most of the existing rotational decoupled parallel mechanism are obtained depending on the experience of the researcher,and don't possess the general theoretical *** on the screw theory,this paper presents the rotational conditions of the parallel mechanism through the analysis of the relationship between the degree of freedom of the parallel mechanism and its *** synthesis rule of the limbs for decoupled rotational parallel mechanism is established according to the twist screw system of the limbs,which assures the decoupling of the rotations in each *** selection principle of the input pairs for the rotation driven limbs is proposed,then the type synthesis method for rotational decoupled parallel mechanisms is *** this type synthesis method,synthesis of the rotational decoupled parallel mechanisms is performed,which can provide a reference for the development of the novel type parallel mechanisms with independent intellectual property rights.

关键词： parallel mechanism screw theory rotational decoupling type synthesis

Synthesis and optical behaviors of 6-seleno-deoxyguanosine

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Science China Chemistry 2014年第2期57卷 314-321页

作者： KAUR Manindar huang zhen Department of Chemistry Georgia State University

We have developed a simple method to synthesize 6-seleno-2′-deoxyguanosine(SedG)by selectively replacing the 6-oxygen atom with *** selenium-atom-specific modification(SAM)alters the optical properties of the naturally occurring2′-deoxyguanosine(dG).Unlike the native dG,the UVabsorption ofSedG is significantly influenced by the pH of the aqueous ***,SedG is fluorescent at the physiological pH and exhibits pH-dependent fluorescence in aqueous ***,SedG has noticeable fluorescence in non-aqueous solutions,indicating its sensitivity to environmental *** is the first time a fluorescent nucleoside by single-atom alteration has been *** nucleosides modified by a single atom have great potential as molecular probes with minimal perturbations to investigate nucleoside interactions with proteins,such as membrane-transporter proteins.

关键词： selenium derivatization and fluorescence nucleoside with single-atom modification fluorescent DNA RNA nucleicacid probes

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Theory of loop algebra on multi-loop kinematic chains and its application

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Science China(Technological Sciences) 2007年第4期50卷 437-447页

作者： huang zhen DING HuaFeng Robotics Research Center Yanshan UniversityQinhuangdao 066004China

Based on the mathematic representation of loops of kinematic chains, this paper proposes the " ⊕ " operation of loops and its basic laws and establishes the basic theorem system of the loop algebra of kinematic chains. Then the basis loop set and its determination conditions, and the ways to obtain the crucial perimeter topological graph are presented. Furthermore, the characteristic perimeter topo-logical graph and the characteristic adjacency matrix are also developed. The most important characteristic of this theory is that for a topological graph which is drawn or labeled in any way, both the resulting characteristic perimeter topological graph and the characteristic adjacency matrix obtained through this theory are unique, and each has one-to-one correspondence with its kinematic chain. This character-istic dramatically simplifies the isomorphism identification and establishes a theoretical basis for the numeralization of topological graphs, and paves the way for numeralization and computerization of the structural synthesis and mechanism design further. Finally, this paper also proposes a concise isomorphism identifica-tion method of kinematic chains based on the concept of characteristic adjacency matrix.

关键词： kinematic chain loop algebra perimeter topological graph isomorphism identification

INSTANTANEOUS KINEMATIC CHARACTERISTICS OF ASPECIAL 3-UPU PARALLEL MANIPULATOR

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Chinese Journal of Mechanical Engineering 2005年第3期18卷 376-381页

作者： Li Shihua huang zhen College of Mechanical Engineering Yanshan University Qinhuangdao 066004 China

The instantaneous kinematics of a special 3-UPU parallel platform manipulator is discussed. First, the instantaneous motions of the 3-UPU manipulator in four kinds of positions and a special manipulator are studied by reciprocal screw theory. Then, the principal screws in one of four positions are obtained. It is shown that the moving platform has five degrees of freedom （DOF） in the initial position or after a translation along the z-axis; In the generic position, the mechanism only has three DOF, moreover the three DOF characteristics are different in different position. The instantaneous kinematic characteristics of alike 3-UPU mechanisms are very different in different position and special structure. The results presented are important to the use of alike 3-UPU parallel manipulator and contribute to the mechanism theory .

关键词： Parallel manipulator Reciprocal screw Principal screws Instantaneous kinematic characteristics

Over-constraint and a Unified Mobility Method for General Spatial Mechanisms Part 1: Essential Principle

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 869-877页

作者： ZENG Daxing LU Wenjuan huang zhen School of Mechanical Engineering Yanshan University

Compared with the parallel mechanisms, the mobility analysis of the general multi-loop spatial mechanisms（GMSMs） is more difficult to obtain correct results. The reason is that its multi-loop is formed through several times of closings and there also exists motion coupling even strong coupling, where the over-constraints are concealed. However, the mobility analysis for this kind of mechanisms has been paid few attentions. A new systemic methodology for analyzing mobility is proposed for GMSMs also based on the screw theory. The key issue for mobility analysis is to recognize the over-constraint. Firstly, three theorems are given and point out： the reason and site of over-constraint occurrence, calculating the number of over-constraints by the screw theory, and how to analyze the over-constraints for a single-loop mechanism as well. Then, three closing forms for GMSMs are proposed including rigid closure, movable closure and dynamic closure, and for the three different forms the different analysis methods are also given. Especially, for the most difficult issue of GMSMs with the multi-loop Closure in many times and the inevitable motion coupling, two important methods are proposed：＂recognizing over-constraints by analyzing relative movement＂ and ＂recognizing over-constraints by virtual loop＂. The two methods are well used to solve the issue. Above-mentioned principles are not only systematic and effective but also unified. They provide a theoretical basis for the general multi-loop spatial mechanisms.

关键词： mobility analysis multi-loop over-constraint closing forms virtual loop

Over-Constraints and a Unified Mobility Method for General Spatial Mechanisms Part 2:Application of the Principle

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Chinese Journal of Mechanical Engineering 2016年第1期29卷 1-10页

作者： LU Wenjuan ZENG Daxing huang zhen School of Mechanical Engineering Yanshan University

The pre-research on mobility analysis presented a unified-mobility formula and a methodology based on reciprocal screw theory by huang, which focused on classical and modem parallel mechanisms. However its range of application needs to further extend to general multi-loop spatial mechanism. This kind of mechanism is not only more complex in structure but also with strong motion coupling among loops, making the mobility analysis even more complicated, and the relevant research has long been ignored. It is focused on how to apply the new principle for general spatial mechanism to those various multi-loop spatial mechanisms, and some new meaningful knowledge is further found. Several typical examples of the genera/multi-loop spatial mechanisms with motion couple even strong motion couple are considered. These spatial mechanisms include different closing way： over-constraint appearing in rigid closure, in movable closure, and in dynamic closure as well; these examples also include two different new methods to solve this kind of issue： the way to recognize over-constraints by analyzing relative movement between two connected links and by constructing a virtual loop to recognize over-constraints. In addition, over-constraint determination tabulation is brought to analyze the motion couple. The researches above are all based upon the screw theory. All these multi-loop spatial mechanisms with different kinds of structures can completely be solved by following the directions and examples, and the new mobility theory based on the screw theory is also proved to be valid. This study not only enriches and develops the theory and makes the theory more universal, but also has a special meaning for innovation in mechanical engineering.

关键词： mobility analysis over-constraint multi-loop spatial mechanism motion coupling 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

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

A MATRIX-FREE IMPLICIT METHOD FOR INCOMPRESSIBLE FLOW AROUND 3D COMPLEX UNDERWATER BODIES

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Journal of Hydrodynamics 2006年第2期18卷 192-198页

作者： huang zhen-yu Miao Guo-ping School of Naval Architecture Ocean and Civil Engineering Shanghai Jiaotong University Shanghai 200030China China Ship Scientific Research Center Wuxi 214082 China

A fast, matrix-free implicit method based on the Lower-Upper Symmetric Gauss-Seidel （LU-SGS） method was developed to solve the three-dimensional incompressible Reynolds-averaged Navier-Stokes equations on multi-block structured grids. The method was applied to the simulations of a variety of flowfields around 3D complex underwater bodies with different appendages. The numerical procedure and results show that the method is efficient, reliable and robust for steady viscous flow simulations.

关键词： Lower-Upper Symmetric Gauss-Seidel(LU-SGS) method incompressible flow underwater bodies,Computational Fluid Dynamics (CFD)