Classification of a Class of 3-RER Parallel Manipulators Using Gröbner Cover and Primary Decomposition of Ideals

2019 ◽  
Author(s):  
Xianwen Kong
Keyword(s):  
Kinematic Chain ◽  
Parallel Manipulators ◽  
Polynomial Systems ◽  
Primary Decomposition ◽  
Type Number ◽  
Systematic Classification ◽  
Operation Modes ◽  
Moving Platform ◽  
The Impact

Abstract Recent studies have revealed that the type/number of operation modes of a parallel manipulator (PM) may vary with the link parameters of the PM. However, current research on the impact of link parameters on the type/number of operation modes of a PM is usually based on intuition. This paper deals with the systematic classification of a 3-RER PM. The 3-RER PM is composed of a base and a moving platform connected by three RER legs, each of which is a serial kinematic chain composed of a revolute (R) joint, a planar (E) joint and an R joint in sequence. The axes of the R joints on the base (or moving platform) are all parallel. At first, a set of constraint equations of the 3-RER PM is first derived. Then using a method called Gröbner cover to calculate the comprehensive Gröbner system of parametric polynomial systems, the 3-RER PM is classified into 21 types. The operation modes of all the types of 3-RER PMs are determined using primary decomposition of ideals. Besides the two 4-DOF (degree-of-freedom) 3T1R operation modes, different types of 3-RER PMs may have up to two more 3-DOF or other types of 4-DOF operation modes. This work is the first systematic study on the impact of link parameters on the operation modes of the 3-RER PM and will contribute to the design and control of 3-RER PMs and research on multi-mode (or reconfigurable) PMs.

scholarly journals Classification of a 3-RER Parallel Manipulator Based on the Type and Number of Operation Modes

2020 ◽  
pp. 1-17
Author(s):  
Xianwen Kong
Keyword(s):  
Parallel Manipulator ◽  
Operation Mode ◽  
Mode Analysis ◽  
Type Number ◽  
Systematic Classification ◽  
Operation Modes ◽  
Solid Foundation ◽  
And Control ◽  
The Impact

Abstract The type/number of operation modes of a parallel manipulator (PM) may vary with the link parameters of the PM. This paper presents a systematic classification of a 3-RER PM based on the type/number of operation modes. The 3-RER PM was proposed as a 4-DOF (degree-of-freedom) 3T1R PM in the literature. Using the proposed method, the classification of a PM based on the type/number of operation modes can be carried out in four steps, including formulation of constraint equations of the PM, preliminary classification of the PM using Gröbner Cover, operation mode analysis of all the types of PMs using primary decomposition of ideals, and identification redundant types of PMs. Classification of the 3-RER PM shows that it has 19 types. Besides the two 4-DOF 3T1R operation modes, different types of 3-RER PMs may have up to two more 3-DOF or other types of 4- DOF operation modes. This work is the first systematic study on the impact of link parameters on the operation modes of the 3-RER PM and provide a solid foundation for further research on the design and control of 3-RER PMs and other multi-mode (or reconfigurable) PMs.

Classification of 3-DOF 3-UPU Translational Parallel Mechanisms Based on Constraint Singularity Loci Using Gröbner Cover

2021 ◽  
Author(s):  
Xianwen Kong
Keyword(s):  
Parallel Mechanism ◽  
Polynomial Systems ◽  
Coordinate Frame ◽  
Parallel Mechanisms ◽  
Systematic Classification ◽  
Starting Point ◽  
Moving Platform ◽  
Singular Configuration ◽  
The Impact

Abstract A 3-UPU translational parallel mechanism (TPM) is one of typical TPMs. Several types of 3-UPU TPMs have been proposed in the literature. Despite comprehensive studies on 3-UPU TPMs in which the joint axes on the base and the moving platform are coplanar, only a few 3-UPU TPMs with a skewed base and moving platform have been proposed. However, the impact of link parameters on singularity loci of such TPMs has not been systematically investigated. The advances in computing CGS (comprehensive Gröbner system) or Gröbner cover of parametric polynomial systems provide an efficient tool for solving this problem. This paper presents a systematic classification of 3-UPU TPMs, especially those with a skewed base and moving platform, based on constraint singularity loci. First, the constraint singularity equation of a 3-UPU TPM is derived. To simplify this equation, the coordinate frame on the base (or moving platform) is set up such that the centers of three U joints are located on different coordinate axes. Using Gröbner Cover, the 3-UPU TPMs are classified into 20 types based on the constraint singularity loci. Finally, a novel 3-UPU TPM is proposed. Unlike most of existing 3-UPU TPMs which can transit to two or more 3-DOF operation modes at a constraint singular configuration, the proposed 3-UPU TPM can only transit to one general 3-DOF operation mode in a constraint singular configuration. The singularity locus divides the workspace of this 3-UPU TPM into two constraint singularity-free regions. This work provides a solid foundation for the design of 3-UPU TPMs and a starting point for the classification of a general 3-UPU parallel mechanism.

scholarly journals Measuring urban form: Overcoming terminological inconsistencies for a quantitative and comprehensive morphologic analysis of cities

2020 ◽  
pp. 239980832091044 ◽  
Author(s):  
Martin Fleischmann ◽  
Ombretta Romice ◽  
Sergio Porta
Keyword(s):  
Spatial Distribution ◽  
Quantitative Analysis ◽  
Urban Form ◽  
Large Scale ◽  
Global Scale ◽  
Urban Morphology ◽  
Systematic Classification ◽  
Social Patterns ◽  
The Impact

Unprecedented urbanisation processes characterise the Great Acceleration, urging urban researchers to make sense of data analysis in support of evidence-based and large-scale decision-making. Urban morphologists are no exception since the impact of urban form on fundamental natural and social patterns (equity, prosperity and resource consumption’s efficiency) is now fully acknowledged. However, urban morphology is still far from offering a comprehensive and reliable framework for quantitative analysis. Despite remarkable progress since its emergence in the late 1950s, the discipline still exhibits significant terminological inconsistencies with regards to the definition of the fundamental components of urban form, which prevents the establishment of objective models for measuring it. In this article, we present a study of existing methods for measuring urban form, with a focus on terminological inconsistencies, and propose a systematic and comprehensive framework to classify urban form characters, where ‘urban form character’ stands for a characteristic (or feature) of one kind of urban form that distinguishes it from another kind. In particular, we introduce the Index of Elements that allows for a univocal and non-interpretive description of urban form characters. Based on such Index of Elements, we develop a systematic classification of urban form according to six categories (dimension, shape, spatial distribution, intensity, connectivity and diversity) and three conceptual scales (small, medium, large) based on two definitions of scale (extent and grain). This framework is then applied to identify and organise the urban form characters adopted in available literature to date. The resulting classification of urban form characters reveals clear gaps in existing research, in particular, in relation to the spatial distribution and diversity characters. The proposed framework reduces the current inconsistencies of urban morphology research, paving the way to enhanced methods of urban form systematic and quantitative analysis at a global scale.

Type Synthesis of Variable Degrees-of-Freedom Parallel Manipulators With Both Planar and 3T1R Operation Modes

2012 ◽  
Author(s):  
Xianwen Kong
Keyword(s):  
Degrees Of Freedom ◽  
Operation Mode ◽  
Parallel Manipulators ◽  
Type Synthesis ◽  
Operation Modes ◽  
Moving Platform ◽  
Multiple Operation ◽  
Schönflies Motion

Parallel manipulators (PMs) with multiple operation modes are novel reconfigurable PMs which use less number of actuators and can be reconfigured without disassembly. Although several classes of PMs with multiple operation modes that have the same DOF (degrees-of-freedom) in all the operation modes have been proposed, only one class of variable-DOF PMs with multiple operation modes — PMs with multiple operation modes that do not have the same DOF in all the operation modes — have been proposed so far. This paper deals with the type synthesis of variable-DOF PMs with both planar and 3T1R (or Schönflies motion which has three translational DOF and 1 rotational DOF) operation modes. The axes of rotation of the moving platform in the planar operation mode are not parallel to the axes of rotation of the moving platform in the 3T1R operation mode. At first, an approach to the type synthesis of PMs with multiple operation modes is recalled. Based on the results on the type synthesis of planar PMs and 3T1R PMs, the types of variable-DOF PMs with both planar and 3T1R operation modes are then obtained. This work can be extended to the type synthesis of other classes of PMs with multiple operation modes.

scholarly journals ІДЕНТИФІКАЦІЯ ТА КЛАСИФІКАЦІЯ ГЛОБАЛЬНИХ ВИКЛИКІВ

2020 ◽  
pp. 36-44
Author(s):  
М. С. Татар
Keyword(s):  
Social Economic ◽  
Practical Significance ◽  
Interstate Relations ◽  
Systematic Classification ◽  
Probability Of Occurrence ◽  
Global Challenge ◽  
Global Challenges ◽  
The Impact

Global challenges complex affect the system of international relations, interstate relations, the nature of interaction between economic entities within the state and between economic entities of different states, requiring a radical transformation and modification of the modern global system and the actions of its actors. The aim of the research is to identification, classification of global challenges by strength of impact and probability of occurrence to further determine their impact on the economic entities behavior and the formation of relationships between them. The subject of the research is the global challenges, the strength of their impact and the probability of occurrence and change in time. The methods of the research: logical-substantive method, method of comparison, methods of induction and deduction, analysis and synthesis. The hypothesis of the research. There is a need to identify and classify global challenges to further determination of their impact on the nature of behavior and the system of relationships of economic entities in the context of global challenges. The statement of basic materials. The concepts of global challenge, global problem, global risk, global crisis, global catastrophe are considered. It is proposed to consider the global challenge as a situation facing a large number of people who are not able to solve it on their own in an adequate time and they need to join efforts to solve it, which can create a global threat that will result in global problems, risks, crises and catastrophes, and be an incentive for global positive change. The classification of global challenges is proposed, which includes geopolitical, social, economic, biological, demographic, climatic, technological, informational, cultural. The originality and practical significance of the research lies in the systematic classification of global challenges in order to further determination of the impact of each group of global challenges on changes in both interstate relations and the nature of interaction between individual entities. Conclusions and perspectives of further research. The proposed by the author classification of global challenges on the basis of the annotated critical analysis of scientific literature, which is presented by 7 groups of global challenges such as geopolitical, social, economic, biological, demographic, climatic, technological, informational, cultural – will be the basis for global challenges impact determining on the nature of behavior and the system of relationships of economic entities in the context of global challenges.

Classification of 6-SPS Parallel Manipulators According to Their Components

2000 ◽  
Author(s):  
Xianwen Kong ◽  
Clément M. Gosselin
Keyword(s):  
Parallel Manipulator ◽  
Kinematic Chain ◽  
Parallel Manipulators ◽  
Rigid Bodies ◽  
Type Synthesis ◽  
Forward Displacement ◽  
Quadratic Equations ◽  
Straight Lines ◽  
Forward Displacement Analysis

Abstract The complexity of the forward displacement analysis (FDA) of 6-SPS parallel manipulators1 varies to a great extent with the change of their geometric parameters. This paper presents a classification of the 6-SPS parallel manipulators according to their components. At first, we give the components for the 6-SPS parallel manipulator. A component refers to a part of the 6-SPS kinematic chain in which the number of actuators is equivalent to the degree of freedom. In addition to the commonly used rigid bodies, points and (straight) lines are also taken as elements of the components. Type synthesis of the 6-SPS parallel manipulators is then performed. The influence of the types of components on the maximal numbers of configurations and the degrees of the characteristic polynomials of the 6-SPS parallel manipulators is then revealed. The number of redundant sensors needed to reduce the FDA of 6-SPS parallel manipulators to the solution of several univariate quadratic equations in sequence based on the component method is also presented.

scholarly journals Open access uptake in Germany 2010–2018: adoption in a diverse research landscape

2021 ◽  
Author(s):  
Anne Hobert ◽  
Najko Jahn ◽  
Philipp Mayr ◽  
Birgit Schmidt ◽  
Niels Taubert
Keyword(s):  
Open Access ◽  
University Research ◽  
Journal Articles ◽  
Max Planck ◽  
Systematic Classification ◽  
Institutional Repositories ◽  
German Research ◽  
Max Planck Society ◽  
The Impact

AbstractThis study investigates the development of open access (OA) to journal articles from authors affiliated with German universities and non-university research institutions in the period 2010–2018. Beyond determining the overall share of openly available articles, a systematic classification of distinct categories of OA publishing allowed us to identify different patterns of adoption of OA. Taking into account the particularities of the German research landscape, variations in terms of productivity, OA uptake and approaches to OA are examined at the meso-level and possible explanations are discussed. The development of the OA uptake is analysed for the different research sectors in Germany (universities, non-university research institutes of the Helmholtz Association, Fraunhofer Society, Max Planck Society, Leibniz Association, and government research agencies). Combining several data sources (incl. Web of Science, Unpaywall, an authority file of standardised German affiliation information, the ISSN-Gold-OA 3.0 list, and OpenDOAR), the study confirms the growth of the OA share mirroring the international trend reported in related studies. We found that 45% of all considered articles during the observed period were openly available at the time of analysis. Our findings show that subject-specific repositories are the most prevalent type of OA. However, the percentages for publication in fully OA journals and OA via institutional repositories show similarly steep increases. Enabling data-driven decision-making regarding the implementation of OA in Germany at the institutional level, the results of this study furthermore can serve as a baseline to assess the impact recent transformative agreements with major publishers will likely have on scholarly communication.

A New Parallel Manipulator With Multiple Operation Modes

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Jaime Gallardo-Alvarado ◽  
Ramon Rodriguez-Castro
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Robot Manipulator ◽  
Kinematic Chain ◽  
Parallel Manipulators ◽  
Operation Modes ◽  
The Family ◽  
Multiple Operation ◽  
Three Degrees Of Freedom

In this work, a new parallel manipulator with multiple operation modes is introduced. The proposed robot is based on a three-degrees-of-freedom (3DOF) parallel manipulator endowed with a three-dof central kinematic chain, where by blocking some specific kinematic pairs, the robot can modify its mobility. Hence, the robot manipulator is able to assume the role of a limited-dof or a nonredundant parallel manipulator. Without loss of generality, the instantaneous kinematics of one member of the family of parallel manipulators generated by the reconfigurable parallel manipulator, the three-RPRRC + RRPRU nonredundant parallel manipulator with decoupled motions, is approached by means of the theory of screws. For the sake of completeness, the finite kinematics of the robot is also investigated. Numerical examples are included with the purpose to clarify the method of kinematic analysis.

Type Synthesis of 3-DOF Parallel Manipulators With Both Planar and Translational Operation Modes

2011 ◽  
Author(s):  
Xianwen Kong
Keyword(s):  
Operation Mode ◽  
Parallel Manipulators ◽  
Planar Motion ◽  
Type Synthesis ◽  
Recent Advances ◽  
Operation Modes ◽  
Open Issue ◽  
Moving Platform ◽  
Multiple Operation ◽  
Planar Parallel Manipulators

Despite recent advances in the type synthesis of parallel manipulators with a mono-operation mode, such as translational parallel manipulators and spherical parallel manipulators, the type synthesis of parallel manipulators with multiple operation modes is still an open issue. This paper deals with the type synthesis of 3-DOF parallel manipulators with both planar and translational operation modes. The type synthesis of planar parallel manipulators, which refer to parallel manipulators in which the moving platform undergoes planar motion, is first dealt with using the virtual chain approach. Then, the types of 3-DOF parallel manipulators with both planar and translational operation modes are obtained. This work can be extended to the type synthesis of other classes of parallel manipulators with multiple operation modes.

scholarly journals SOME COMMENTS ON A CATALOGUE OF ATMOSPHERIC PARAMETERS AND [Fe/H] DETERMINATIONS

1976 ◽  
Vol 72 ◽  
pp. 29-46
Author(s):  
G. Cayrel de Strobel
Keyword(s):  
Detailed Analysis ◽  
High Dispersion ◽  
Physical Parameters ◽  
List Type ◽  
Type Number ◽  
Spectral Classification ◽  
Atmospheric Parameters ◽  
Nearby Stars ◽  
The Impact

A few examples are given showing the utility of the catalogue of iron/hydrogen determinations for astrophysical researches. These are: (a)Histograms of dwarfs and giants analyzed in detail with spectral type between O and M.(b)Logarithmic abundances diagrams of given stars.(c)The impact on spectral classification of high-dispersion-detailed-analysis results.(d)The use of well-determined chemical and physical parameters of nearby stars for the construction of HR diagrams in the (Mbol –log Teff) plane.The spectra of F, G and K stars having the iron lines at their best visibility, special emphasis has been given to the results concerning these stars.

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