Topological Structural Design of Umbrella-Shaped Deployable Mechanisms Based on New Spatial Closed-Loop Linkage Units

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Wen-ao Cao ◽  
Donghao Yang ◽  
Huafeng Ding
Keyword(s):  
Structural Design ◽  
Closed Loop ◽  
Space Exploration ◽  
Degree Of Freedom ◽  
Structural Symmetry ◽  
Potential Applications ◽  
Good Potential

The umbrella linkage is one of the most classical deployable mechanisms. This paper concentrates on topological structural design of a family of umbrella-shaped deployable mechanisms based on new two-layer and two-loop spatial linkage units. First, deployable units are developed systematically from two-layer and two-loop linkage with four revolute pair (4R) coupling chains. Then, mobile connection modes of the deployable units are established based on the conditions of one degree-of-freedom (DOF) and structural symmetry. Finally, umbrella-shaped deployable mechanisms are constructed based on the developed deployable units and the established mobile connection modes. Like umbrellas, the designed deployable mechanisms can be actuated in a simple and reliable way, and those mechanisms have good potential applications in the fields of architecture, manufacturing, space exploration, and recreation.

Design and Development of a Novel 2-Degree-of-Freedom Parallel Robot

Robotica ◽  
2019 ◽  
Vol 38 (1) ◽  
pp. 1-14
Author(s):  
Changxi Cheng ◽  
Wenkai Huang ◽  
Chunliang Zhang
Keyword(s):  
Structural Design ◽  
Medical Science ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Degree Of Freedom ◽  
Static Stiffness ◽  
Reachable Workspace ◽  
Workspace Analysis ◽  
Potential Applications ◽  
Speed Performance

SummaryParallel robots are widely used in the fields of manufacturing, medical science, education, scientific research, etc. Many studies have been conducted on the topic already. However, shortcomings still exist, especially in certain situations. To meet the demand of good speed and load performances at the same time, this work presents a novel 2-degree-of-freedom parallel robot. The structural design, static, stiffness, and reachable workspace analysis of the robot are given in the manuscript. Experiment regarding the accuracy and speed performance is conducted, and the results are provided. In the end, potential applications of the proposed robot are suggested.

scholarly journals Circular RNAs: Potential Applications as Therapeutic Targets and Biomarkers in Breast Cancer

2021 ◽  
Vol 7 (1) ◽  
pp. 2
Author(s):  
Debina Sarkar ◽  
Sarah D. Diermeier
Keyword(s):  
Breast Cancer ◽  
Translational Regulation ◽  
Closed Loop ◽  
Mechanisms Of Action ◽  
Circular Rnas ◽  
Therapeutic Approaches ◽  
Mirna Sponge ◽  
Bodily Fluids ◽  
Potential Applications ◽  
Non Coding Rnas

Circular RNAs (circRNAs) are a class of non-coding RNAs that form a covalently closed loop. A number of functions and mechanisms of action for circRNAs have been reported, including as miRNA sponge, exerting transcriptional and translational regulation, interacting with proteins, and coding for peptides. CircRNA dysregulation has also been implicated in many cancers, such as breast cancer. Their relatively high stability and presence in bodily fluids makes cancer-associated circRNAs promising candidates as a new biomarker. In this review, we summarize the research undertaken on circRNAs associated with breast cancer, discuss circRNAs as biomarkers, and present circRNA-based therapeutic approaches.

scholarly journals A New Method for Type Synthesis of 2R1T and 2T1R 3-DOF Redundant Actuated Parallel Mechanisms with Closed Loop Units

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Yongquan Li ◽  
Yang Zhang ◽  
Lijie Zhang
Keyword(s):  
Closed Loop ◽  
Screw Theory ◽  
Line Graph ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Allocation Criteria ◽  
Grassmann Line Geometry ◽  
Moving Platform ◽  
Atlas Method

Abstract The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms, or using screw theory to perform multiple getting intersection and union to complete type synthesis. The number of redundant parallel mechanisms obtained by these two methods is limited. In this paper, based on Grassmann line geometry and Atlas method, a novel and effective method for type synthesis of redundant actuated parallel mechanisms (PMs) with closed-loop units is proposed. Firstly, the degree of freedom (DOF) and constraint line graph of the moving platform are determined successively, and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph, and a branch constraint allocation scheme is formulated based on the allocation criteria. Secondly, a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop units. Finally, the branch chains that meet the requirements of branch chains configuration criteria and F&C (degree of freedom & constraint) line graph are assembled. In this paper, two types of 2 rotational and 1 translational (2R1T) redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational (2T1R) redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples, and 238, 92 and 15 new configurations were synthesized. All the mechanisms contain closed-loop units, and the mechanisms and the actuators both have good symmetry. Therefore, all the mechanisms have excellent comprehensive performance, in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently controlled. The instantaneous analysis shows that all mechanisms are not instantaneous, which proves the feasibility and practicability of the method.

Two-Degree-of-Freedom Helicopter Closed-Loop Identification through a Cascade Controller

2011 ◽  
Vol 403-408 ◽  
pp. 4649-4658 ◽  
Author(s):  
Pouya Ghalei ◽  
Alireza Fatehi ◽  
Mohamadreza Arvan
Keyword(s):  
Closed Loop ◽  
Flight Simulation ◽  
Degree Of Freedom ◽  
Input Output ◽  
Closed Loop Identification ◽  
Practical Algorithm ◽  
Nonlinear Autoregressive Model ◽  
And Control ◽  
Nonlinear Autoregressive ◽  
Two Degree Of Freedom

Input-Output data modeling using multi layer perceptron networks (MLP) for a laboratory helicopter is presented in this paper. The behavior of the two degree-of-freedom platform exemplifies a high order unstable, nonlinear system with significant cross-coupling between pitch and yaw directional motions. This paper develops a practical algorithm for identifying nonlinear autoregressive model with exogenous inputs (NARX) and nonlinear output error model (NOE) through closed loop identification. In order to collect input-output identifier pairs, a cascade state feedback (CSF) controller is introduced to stabilize the helicopter and after that the procedure of system identification is proposed. The estimated models can be utilized for nonlinear flight simulation and control and fault detection studies.

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.

Continuous Closed-Loop 4-Degree-of-Freedom Holdable Haptic Guidance

2020 ◽  
Vol 5 (4) ◽  
pp. 6853-6860
Author(s):  
Julie M. Walker ◽  
Allison M. Okamura
Keyword(s):  
Closed Loop ◽  
Degree Of Freedom ◽  
Haptic Guidance

Two-degree-of-freedom control design for ball screw driving table using full-closed loop

2004 ◽  
Vol 2004.57 (0) ◽  
pp. 441-442
Author(s):  
Hiroshi HAMAMATSU ◽  
Kentaro Kondo ◽  
Shigeru FUTAMI ◽  
Teruo TSUJI ◽  
Akihiro YAMAMOTO ◽  
...  
Keyword(s):  
Closed Loop ◽  
Control Design ◽  
Degree Of Freedom ◽  
Ball Screw ◽  
Screw Driving ◽  
Two Degree Of Freedom

scholarly journals Numerical Approach to the Kinematic Analysis of Deployable Structures Forming a Closed Loop

2006 ◽  
Vol 220 (7) ◽  
pp. 1045-1056 ◽  
Author(s):  
W W Gan ◽  
S Pellegrino
Keyword(s):  
Systematic Study ◽  
Numerical Scheme ◽  
Closed Loop ◽  
Numerical Approach ◽  
The Other ◽  
Deployable Structures ◽  
Potential Applications ◽  
Motion Range ◽  
Polygonal Shape ◽  
Spatial Linkages

This article is concerned with spatial linkages forming a closed loop. In one extreme configuration (deployed), these linkages form a frame of polygonal shape, such as a square or a hexagon, and in the other extreme (folded), configuration form a tight bundle. Throughout their motion range, they have mobility one. These linkages have potential applications for next-generation deployable spacecraft structures. The article presents a systematic study of the kinematics of closed-loop structures with these special properties and a numerical scheme for simulating their deployment without making any assumptions about particular symmetry features. The proposed simulation technique is applied to three examples that show different behaviour during deployment.

Reverse Kinematic Analysis of the Spatial Six Axis Robotic Manipulator With Consecutive Joint Axes Parallel

2007 ◽  
Author(s):  
Javier Rolda´n Mckinley ◽  
Carl Crane ◽  
David B. Dooner
Keyword(s):  
Kinematic Analysis ◽  
Closed Loop ◽  
Degree Of Freedom ◽  
Repetitive Motion ◽  
Spatial Mechanism ◽  
Joint Axis ◽  
Specific Geometry ◽  
Noncircular Gears ◽  
Six Degree Of Freedom ◽  
The Given

This paper introduces a reconfigurable one degree-of-freedom spatial mechanism that can be applied to repetitive motion tasks. The concept is to incorporate five pairs of noncircular gears into a six degree-of-freedom closed-loop spatial chain. The gear pairs are designed based on the given mechanism parameters and the user defined motion specification of a coupler link of the mechanism. It is shown in the paper that planar gear pairs can be used if the spatial closed-loop chain is comprised of six pairs of parallel joint axes, i.e. the first joint axis is parallel to the second, the third is parallel to the fourth, …, and the eleventh is parallel to the twelfth. This paper presents the detailed reverse kinematic analysis of this specific geometry. A numerical example is presented.

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