scholarly journals Virtual and Physical Prototyping of Reconfigurable Parallel Mechanisms with Single Actuation

2021 ◽  
Vol 11 (15) ◽  
pp. 7158
Author(s):  
Alexey Fomin ◽  
Daniil Petelin ◽  
Anton Antonov ◽  
Victor Glazunov ◽  
Marco Ceccarelli
Keyword(s):  
Computer Aided Design ◽  
Screw Theory ◽  
Complex Geometry ◽  
Kinematic Chain ◽  
Parallel Mechanisms ◽  
Mobility Analysis ◽  
Kinematic Chains ◽  
Physical Prototype ◽  
Detailed Computer ◽  
Aided Design

The paper presents novel models of reconfigurable parallel mechanisms (RPMs) with a single active degree-of-freedom (1-DOF). The mechanisms contain three to six identical kinematic chains, which provide three (for the tripod) to zero (for the hexapod) uncontrollable DOFs. Screw theory is applied to carry out mobility analysis and proves the existence of controllable and uncontrollable DOFs of these mechanisms. Each kinematic chain in the synthesized mechanisms consists of planar and spatial parts. Such a design provides them with reconfiguration capabilities even when the driving link is fixed. This allows reproduction of diverse output trajectories without using additional actuators. In this paper, the model of a mechanism with six kinematic chains (hexapod) has been virtually and physically prototyped. The designing and assembling algorithms are developed using the detailed computer-aided design (CAD) model, which was further used to carry out kinetostatic analysis considering complex geometry of mechanism elements and friction among all contacting surfaces of joints. The developed virtual prototype and its calculation data have been further applied to fabricate mechanism elements and assemble an actuated full-scale physical prototype for future testing.

Mobility Analysis of Parallel Mechanisms Based on Screw Theory and the Concept of Equivalent Serial Kinematic Chain

2005 ◽  
Author(s):  
Xianwen Kong ◽  
Cle´ment M. Gosselin
Keyword(s):  
Systematic Approach ◽  
Screw Theory ◽  
Kinematic Chain ◽  
Second Step ◽  
Parallel Mechanisms ◽  
Mobility Analysis ◽  
Single Loop ◽  
Kinematic Chains ◽  
Serial Chain ◽  
Parallel Kinematic

This paper presents a systematic approach for the mobility analysis of parallel mechanisms. The method is based on screw theory and the concept of equivalent serial chain. An equivalent serial kinematic chain of a k-legged PKC (parallel kinematic chain) is defined as a serial kinematic chain which has the same twist system and the wrench system as the k-legged PKC. Using the proposed approach, the mobility analysis of a PKC is performed in two steps. The first step is the instantaneous mobility analysis, and the second step is the full-cycle mobility inspection. The first step is dealt with based on screw theory. The second step is performed with the aid of the concept of equivalent serial chain and the types of multi-DOF overconstrained single-loop kinematic chains. The proposed approach is illustrated with several examples.

Jacobian Derivation of 5-DOF 3R2T Parallel Mechanisms

2004 ◽  
Author(s):  
Qinchuan Li ◽  
Xudong Hu ◽  
Zhen Huang
Keyword(s):  
Degrees Of Freedom ◽  
Jacobian Matrix ◽  
Screw Theory ◽  
Kinematic Chain ◽  
Parallel Mechanisms ◽  
Mobility Analysis

This paper presents a method for the Jacobian derivation of 5-DOF 3R2T PMs (parallel mechanisms), where 3R denotes three rotational DOFs (degrees of freedom) and 2T denotes two translational DOFs. First the mobility analysis of such kind of parallel mechanisms is reviewed briefly. The Jacobian matrix of the single limb kinematic chain is obtained via screw theory, which is a 6 × 5 matrix. Then it is shown that the mobility analysis of such kind of PM is important when simplifying the 6 × 5 matrix into a 5 × 5 Jacobian matrix. After obtaining the 5 × 5 Jacobian matrix for each limb, a 5 × 5 Jacobian matrix for the whole mechanism can be established.

An approach for mobility and force/motion transmissibility analysis of parallel mechanisms based on screw theory and CAD technology

2021 ◽  
Vol 13 (10) ◽  
pp. 168781402110507
Author(s):  
Yue Ma ◽  
Qi Liu ◽  
Mian Zhang ◽  
Bin Li ◽  
Zhenzhong Liu
Keyword(s):  
Conceptual Model ◽  
Computer Aided Design ◽  
Semantic Information ◽  
Screw Theory ◽  
Parallel Mechanisms ◽  
Rule Based ◽  
The Past ◽  
Joint Axis ◽  
Kinematic Diagram ◽  
Aided Design

By integrating screw theory with computer-aided design (CAD) technology, this paper presents an effective and automated methodology for mobility and force/motion transmissibility analysis of parallel mechanisms (PMs). In this approach, A kinematic diagram of a PM termed as the conceptual model, which consists of a solid assembly and several skeleton elements in the form of datum entities and non-geometric entities such as parameters, equations and semantic information, is built by using the 3D modeling capabilities of SolidWorks. For each limb of the PM, a rule-based reasoning (RBR) system is developed based upon the dual and reciprocal properties of screw systems, allowing its own twist/wrench subspaces to be determined automatically by using the joint axis features extracted from the conceptual model. These considerations lead to an automated procedure that can be used to generate the general Jacobian of PMs, allowing the mobility and force/motion transmissibility analysis to be carried out automatically, a work that had to be done manually in the past. Based on the proposed approach, a software package is developed and examples are given to verify its effectiveness.

Mobility Analysis of a Novel 3-5R Parallel Mechanism Family

2004 ◽  
Vol 126 (1) ◽  
pp. 79-82 ◽  
Author(s):  
Q. C. Li ◽  
Z. Huang
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Kinematic Chain ◽  
Parallel Mechanisms ◽  
Mobility Analysis

Mobility analysis of a novel 3-5R parallel mechanism family whose limb consists of a 2R and a 3R parallel subchain is performed by the aid of screw theory. A mobility criterion applicable to such 3-leg parallel mechanisms in which each kinematic chain contains five kinematic pairs is proposed. It is shown that under different structural conditions, the 3-5R parallel mechanism can have 3, 4, or 5 DOF (degrees of freedom). The structural conditions that guarantee the full-cycle mobility are analyzed. The analysis and the method presented in this paper will be helpful in using such a 3-5R parallel mechanism family and introduce new insights into the mobility analysis of parallel mechanisms.

scholarly journals Synthesis and Analysis of a Novel Linkage Mechanism with the Helical Motion of the End-Effector

Robotics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 53
Author(s):  
Alexey Fomin ◽  
Daniil Petelin ◽  
Andreas Jahr
Keyword(s):  
Computer Aided Design ◽  
Functional Performance ◽  
Cad Model ◽  
Kinematic Scheme ◽  
Linkage Mechanism ◽  
End Effector ◽  
Kinematic Chains ◽  
Cyclic Movement ◽  
Physical Prototype ◽  
Aided Design

The proposed study is focused on the development of a novel modification of the slider-crank mechanism, the kinematic scheme of which is organized by coupling planar and spatial (screw) kinematic chains. The structure of this mechanism provides the end-effector with a cyclic movement along a helicoidal trajectory, while all other links have planar motions. A kinematic analysis of the synthesized mechanism is discussed in this study. The motion variables of the end-effector at different pitches in the screw joints are determined analytically and numerically. Based on the mechanism’s kinematic scheme, its assembling computer-aided design (CAD) model has been created, in accordance with which a physical prototype has been built. A functional performance of the prototype is studied by comparing the displacements of its end-effector with analogical displacements of the CAD model. The question of the technological application of the developed mechanism for spring winding and various objects’ screwing has been considered in this study.

Synthesis of Deployable/Foldable Single Loop Mechanisms With Revolute Joints

2011 ◽  
Vol 3 (3) ◽  
Author(s):  
Zongquan Deng ◽  
Hailin Huang ◽  
Bing Li ◽  
Rongqiang Liu
Keyword(s):  
Computer Aided Design ◽  
Geometric Approach ◽  
Mobility Analysis ◽  
Design Models ◽  
Single Loop ◽  
Kinematic Chains ◽  
Design And Synthesis ◽  
Revolute Joints ◽  
Computer Aided ◽  
Aided Design

This paper presents a geometric approach for design and synthesis of deployable/foldable single loop mechanisms with pure revolute joints. The basic kinematic chains with symmetric mobility are first synthesized, and an intuitive geometric method is proposed for the mobility analysis of these kinematic chains. The deployable/foldable single loop mechanisms can be regarded as a combination of the basic kinematic chains with nontrivial mobility intersection, under this approach, the 5R to 8R single loop mechanisms with symmetric mobility are synthesized systematically. The method for determining the positions of the joint axes on polyhedral links is also proposed, so that the mechanism can be fully deployed or fully folded without suffering from physical interference. Under this framework, a class of novel deployable/foldable single loop mechanisms is developed. The computer-aided design models for typical examples are built to illustrate their feasibility.

scholarly journals The Influence of Exposure Energy Density on Porosity and Microhardness of the SLM Additive Manufactured Elements

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2304 ◽  
Author(s):  
Janusz Kluczyński ◽  
Lucjan Śnieżek ◽  
Krzysztof Grzelak ◽  
Janusz Mierzyński
Keyword(s):  
Computer Aided Design ◽  
Complex Geometry ◽  
Final Analysis ◽  
Machine Building ◽  
Layer By Layer ◽  
Laser Melting ◽  
Measurement Results ◽  
Computer Aided ◽  
Exposure Energy ◽  
Aided Design

Selective laser melting (SLM) is an additive manufacturing technique. It allows elements with very complex geometry to be produced using metallic powders. A geometry of manufacturing elements is based only on 3D computer-aided design (CAD) data. The metal powder is melted selectively layer by layer using an ytterbium laser. This paper contains the results of porosity and microhardness analysis made on specimens manufactured during a specially prepared process. Final analysis helped to discover connections between changing hatching distance, exposure speed and porosity. There were no significant differences in microhardness and porosity measurement results in the planes perpendicular and parallel to the machine building platform surface.

Design and Mobility Analysis of Large Deployable Mechanisms Based on Plane-Symmetric Bricard Linkage

2016 ◽  
Author(s):  
Xiaozhi Qi ◽  
Bing Li ◽  
Zhihuai Miao ◽  
Hailin Huang
Keyword(s):  
Computer Aided Design ◽  
Closed Loop ◽  
Degree Of Freedom ◽  
Mobility Analysis ◽  
Plane Symmetric ◽  
Analysis And Design ◽  
Geometric Conditions ◽  
Deployable Mechanism ◽  
Vertical Bars ◽  
Aided Design

In this paper, a class of large deployable mechanisms constructed by plane-symmetric Bricard linkage is presented. The plane-symmetric Bricard linkage is a closed-loop over-constrained spatial mechanism composed of six hinge-jointed bars, which has one plane of symmetry during its deployment process. The kinematic analysis of the linkage is presented from the perspectives of geometric conditions, closure equations and degree of freedom. The results illustrates that the linkage has one degree of freedom, and it can be deployed from the folded configuration to one rectangle plane. Therefore, the plane-symmetric Bricard linkage can be used to construct lager deployable mechanism as basic deployable unit. Four plane-symmetric Bricard linkages can be assembled to a quadrangular module by sharing the vertical bars of adjacent units. The module is a multi-loop deployable mechanism and has one degree of freedom by the mobility analysis. Large deployable mast, deployable plane truss and deployable ring are built by a plurality of plane-symmetric Bricard linkages. The computer-aided design models for typical examples are built to illustrate their feasibility and validate the analysis and design methods.

Towards Computer Aided Design and Analysis of Spatial Flexure Mechanisms

2016 ◽  
Author(s):  
Omer Anil Turkkan ◽  
Hai-Jun Su
Keyword(s):  
Computer Aided Design ◽  
Screw Theory ◽  
Design Tool ◽  
Future Design ◽  
Linear Elastic ◽  
Wide Range ◽  
Speed Up ◽  
System Equations ◽  
Compliance Matrices ◽  
Aided Design

Flexure mechanisms are the central part of numerous precision instruments and devices that are used in a wide range of science and engineering applications and currently, design of flexure mechanisms often heavily relies on designers’ previous hands-on experience. Therefore, a design tool that will speed up the design process is needed and this paper will introduce a systematic approach for building the necessary equations that are based on screw theory and linear elastic theory to analyze flexure mechanisms. A digital library of commonly used flexure elements must be available for a design tool and therefore, we first present the compliance matrices of commonly used flexure components. Motion twists and force wrenches of the screw theory can be related with these compliance matrices. Then, we introduce an algorithm that constructs the required linear system equations from individual compliance equations. This algorithm is applicable to flexure mechanisms with serial, parallel or hybrid chains. Finally, the algorithm is tested with a flexure mechanisms and it is shown that this approach can be the core of a future design tool.

scholarly journals An Interactive Tool for Automatic Predimensioning and Numerical Modeling of Arch Dams

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
D. J. Vicente ◽  
J. San Mauro ◽  
F. Salazar ◽  
C. M. Baena
Keyword(s):  
Computer Aided Design ◽  
Complex Geometry ◽  
Design Procedure ◽  
Software Tool ◽  
Gravity Dams ◽  
Detailed Model ◽  
Arch Dams ◽  
Double Curvature ◽  
Aided Design ◽  
Mass Volume

The construction of double-curvature arch dams is an attractive solution from an economic viewpoint due to the reduced volume of concrete necessary for their construction as compared to conventional gravity dams. Due to their complex geometry, many criteria have arisen for their design. However, the most widespread methods are based on recommendations of traditional technical documents without taking into account the possibilities of computer-aided design. In this paper, an innovative software tool to design FEM models of double-curvature arch dams is presented. Several capabilities are allowed: simplified geometry creation (interesting for academic purposes), preliminary geometrical design, high-detailed model construction, and stochastic calculation performance (introducing uncertainty associated with material properties and other parameters). This paper specially focuses on geometrical issues describing the functionalities of the tool and the fundamentals of the design procedure with regard to the following aspects: topography, reference cylinder, excavation depth, crown cantilever thickness and curvature, horizontal arch curvature, excavation and concrete mass volume, and additional elements such as joints or spillways. Examples of application on two Spanish dams are presented and the results obtained analyzed.

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