Topological Representations and Characteristics of Variable Kinematic Joints

2005 ◽  
Vol 128 (2) ◽  
pp. 384-391 ◽  
Author(s):  
Hong-Sen Yan ◽  
Chin-Hsing Kuo
Keyword(s):  
Graph Theory ◽  
Degrees Of Freedom ◽  
Structural Synthesis ◽  
Characteristic Analysis ◽  
Push Button ◽  
Walking Machines ◽  
Operation Process ◽  
Variable Topology ◽  
Topological Characteristics ◽  
Kinematic Joint

There exist some mechanisms with variable topologies that have interesting applications, for examples, legged walking machines, mechanical push-button stopper locks, and various toys. A variable kinematic joint is a kinematic joint that is capable of topological variation in a mechanism with variable topology. This work aims at the topological representations and characteristic analysis of variable kinematic joints. During the operation process of a mechanism, the topology states of a variable kinematic joint can be expressed symbolically as the joint sequences, graphically the digraphs, and mathematically the matrices. With the applications of graph theory, it proves that the topological characteristics of variable kinematic joints appeared with the abilities of reversibility, continuity, variability of degrees of freedom, joint homomorphism, contractibility, and expansibility. Two examples are provided for illustrating how the proposed concepts can be used to analyze and synthesize the variable joints. The results of this work provide a logical foundation for the systematic structural synthesis regarding the kinematic joints and mechanisms with variable topologies.

An Innovative Approach to Detect Isomorphism in Planar and Geared Kinematic Chains Using Graph Theory

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Vinjamuri Venkata Kamesh ◽  
Kuchibhotla Mallikarjuna Rao ◽  
Annambhotla Balaji Srinivasa Rao
Keyword(s):  
Graph Theory ◽  
Degrees Of Freedom ◽  
Quantitative Measure ◽  
Simple Algorithm ◽  
Isomorphism Problem ◽  
Innovative Approach ◽  
Two Degrees Of Freedom ◽  
Kinematic Chains ◽  
Topological Characteristics ◽  
Interesting Area

Detection of isomorphism in planar and geared kinematic chains (GKCs) is an interesting area since many years. Enumeration of planar and geared kinematic chains becomes easy only when isomorphism problem is resolved effectively. Many researchers proposed algorithms based on topological characteristics or some coding which need lot of computations and comparisons. In this paper, a novel and simple algorithm is proposed based on graph theory by which elimination of isomorphic chains can be done very easily without any tedious calculations or comparisons. A new concept “Net distance” is proposed based on the graph theory to be a quantitative measure to assess isomorphism in planar kinematic chains (PKCs) as well as GKCs. The proposed algorithm is applied on nine-link two-degrees-of-freedom (DOF) distinct kinematic chains completely and the results are presented. Algorithm is tested on examples from eight-link 1-DOF, ten-link 1-DOF, 12-link 1-DOF, and 15link 4-DOF PKCs. The algorithm is also tested on four-, six-link 1-DOF GKCs to detect isomorphism. All the results are in agreement with the existing literature.

Kinematic Synthesis of Deployable-Foldable Truss Structures Using Graph Theory, Part 1: Graph Generation

1995 ◽  
Vol 117 (1) ◽  
pp. 112-116 ◽  
Author(s):  
D. B. Warnaar ◽  
M. Chew
Keyword(s):  
Graph Theory ◽  
Conceptual Design ◽  
Design Process ◽  
Degrees Of Freedom ◽  
Truss Structure ◽  
Truss Structures ◽  
Structural Synthesis ◽  
Deployable Structures ◽  
Kinematic Synthesis ◽  
Graph Generation

Kinematic structural synthesis has been relatively successful when applied to the conceptual design of mechanisms. The approach presented in this paper, however, views the design process from an initial standpoint of a truss structure. First, graphs are generated that represent truss structures with a given number of nodes and links. Each graph is then modified by designating certain edges in the graph to represent links in the structure that incorporate additional degrees of freedom. In so doing, the graph of a structure is transformed into one representing a mechanism. A procedure is presented that enables the exhaustive generation of these graphs for deployable structures of any given number of nodes and links. From these graphs, it is then possible to obtain enumerable novel deployable truss structures as well as those that have been reported in the literature.

Structural Synthesis of a Class of Five-DOF Parallel Robot Mechanisms Based on Single-Opened-Chain Units

2001 ◽  
Author(s):  
Qiong Jin ◽  
Ting-Li Yang ◽  
An-Xin Liu ◽  
Hui-Ping Shen ◽  
Fang-Hua Yao
Keyword(s):  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Degree Of Freedom ◽  
Structural Synthesis ◽  
Structure Synthesis ◽  
Systematic Methodology ◽  
Rotational Degrees Of Freedom ◽  
Topological Characteristics

Abstract Based on the units of single-opened-chain limb, some topological characteristics of rank-degenerate parallel robot mechanisms are revealed, and a systematic methodology for the structural synthesis of a class of five degree-of-freedom parallel robot mechanisms is put forward in this paper. 49 new mechanisms with three translational and two rotational degrees of freedom are synthesized and classified. The method proposed in this paper is of universal significance and has been used for the structure synthesis of rank-degenerate parallel robot mechanisms with other kinematics output types.

An Application of Graph Theory for the Detection of Degenerate Structures in Planetary Gear Trains

2021 ◽  
Author(s):  
Essam L. Esmail ◽  
Anahed H. Juber
Keyword(s):  
Graph Theory ◽  
Adjacency Matrix ◽  
Degrees Of Freedom ◽  
Planetary Gear ◽  
Connectivity Matrix ◽  
Structural Synthesis ◽  
Multiple Degrees Of Freedom ◽  
Planetary Gear Trains ◽  
Gear Trains ◽  
Straightforward Approach

Abstract One of the most important steps in the structural synthesis of planetary gear trains is to eliminate degenerate structures. First, the graph theory is used to represent planetary gear trains (PGTs). Second, a procedure is developed to identify fundamental geared entities (FGEs). Further, the single-planet FGEs are shown to have one-DOF and, therefore, cannot constitute a degenerate structure. It is this that allows a significant reduction in the calculation in relation to other methods of diagnosing degenerate structures. Third, using the concepts of FGEs and the notation of the associated adjacency matrix, an algorithm is developed for the detection of degenerate structures in PGTs. The algorithm is based on the fact that any degenerate structure is a PGT formed by two fundamental geared entities with common edges and/or vertices equal to or more than 3. Forth, the concept of connectivity between single-planet FGEs is introduced and a simple, straightforward approach for deducting the connectivity matrix from the adjacency matrix is developed. The new vertex-edge mobility criterion does not require combinatorial analysis. Besides, the method is applicable to one and multiple degrees of freedom PGTs, it is also applicable to multi-planet PGTs and complex PGTs, including contrary examples found in the literature.

Mechanical Structural Interference Detection for Dedicated Hybrid Transmissions

2021 ◽  
Vol 143 (9) ◽  
Author(s):  
Hanqiao Sun ◽  
Xiangyang Xu ◽  
Yanfang Liu ◽  
Peng Dong ◽  
Shuhan Wang ◽  
...  
Keyword(s):  
Graph Theory ◽  
Graph Model ◽  
Planetary Gear ◽  
Modeling Method ◽  
Structural Synthesis ◽  
Original Graph ◽  
Power Sources ◽  
Detection Approach ◽  
Hybrid Transmission ◽  
Planetary Gear System

Abstract Planetary gear set (PGS) has been one of the best components to constitute a transmission configuration, including the dedicated hybrid transmission (DHT). Using different synthesis approaches, the DHT configurations can be obtained through algorithms. However, different synthesis results correspond to different connection states of the planetary gear system. There are a certain number of results that violate the motion requirements of the mechanical principal need to be detected and removed. Therefore, this paper presents a novel modeling method to systematically remove the interference structures, with graph theory in structural synthesis. Based on the original graph theory, this paper proposes an equivalent replacement modeling method to convert the motor graph model into a brake-like graph model. Based on the conversion, avoid the appearance of the hanging points in the graph model. By applying the proposed approach, a DHT structure proves the feasibility of the method. The proposed detection approach can systematically detect all the PGS-based transmission with multi-PGSs, multi-shifting elements, and multi-power sources.

scholarly journals Application of Linear and Nonlinear Graphs in Structural Synthesis of Kinematic Chains

1973 ◽  
Vol 95 (2) ◽  
pp. 525-532 ◽  
Author(s):  
M. Huang ◽  
A. H. Soni
Keyword(s):  
Mathematical Model ◽  
Graph Theory ◽  
Structural Analysis ◽  
Three Dimensional ◽  
Structural Synthesis ◽  
Kinematic Chains ◽  
Piston Cylinder ◽  
General Constraints ◽  
Analysis And Synthesis ◽  
Linear And Nonlinear

Using graph theory and Polya’s theory of counting, the present paper performs structural synthesis and analysis of planar and three-dimensional kinematic chains. The Section 2 of the paper develops a mathematical model that permits one to perform structural analysis and synthesis of planar kinematic chains with kinematic elements such as revolute pairs, cam pairs, springs, belt-pulley, piston-cylinder, and gears. The theory developed is applied to enumerate eight-link kinematic chains with these kinematic elements. The Section 3 of the paper develops a mathematical model that permits one to perform structural analysis and synthesis of multi-loop spatial kinematic chains with higher and lower kinematic pairs. The theory developed is applied to enumerate all possible two-loop kinematic chains with or without general constraints.

Design and its characteristic analysis of a wheeled train uncoupling robot with multi-degrees-of-freedom

2015 ◽  
Vol 230 (10) ◽  
pp. 1673-1684 ◽  
Author(s):  
Jianjun Yao ◽  
Yuxuan Huang ◽  
Guilin Jiang ◽  
Shuang Gao ◽  
Rui Xiao ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Robot Manipulator ◽  
Vital Role ◽  
Real Time Control ◽  
Characteristic Analysis ◽  
Time Control ◽  
Operational Space ◽  
Wheeled Robot ◽  
Marshalling Yard ◽  
Cargo Transportation

Freight trains play a vital role in cargo transportation in the world. The freight cars need to be redistributed for marshalling according to different destinations in the hump yard. Humans are usually employed to uncouple the freight cars in the marshalling yard. However, the work environment is difficult to work in, because of its potential danger and the effects of the surrounding environment can have a very serious impact on human’s health. A wheeled robot is developed to replace humans to finish the uncoupling task. It has four degrees-of-freedom with flexible motion. Based on the D-H method, the kinematics, including the forward and the inverse kinematics, is firstly analysed. The dynamic analysis is then studied by Newton–Euler equations. The workspace is lastly investigated to verify its operational space such that the coupler can be easily reached by the robot manipulator. Those characteristic analyses provide a basis for motion planning and real-time control of the robot.

scholarly journals A Translational Three-Degrees-of-Freedom Parallel Mechanism With Partial Motion Decoupling and Analytic Direct Kinematics

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Huiping Shen ◽  
Damien Chablat ◽  
Boxiong Zeng ◽  
Ju Li ◽  
Guanglei Wu ◽  
...  
Keyword(s):  
Parallel Mechanism ◽  
Design Theory ◽  
Degrees Of Freedom ◽  
Analytic Solutions ◽  
Inverse Kinematic ◽  
Kinematic Modeling ◽  
Topological Design ◽  
Prismatic Joints ◽  
Topological Characteristics ◽  
Three Degrees Of Freedom

Abstract According to the topological design theory and the method of parallel mechanism (PM) based on position and orientation characteristic (POC) equations, this paper studied a three-degrees-of-freedom (3-DOF) translational PM that has three advantages, i.e., (i) it consists of three fixed actuated prismatic joints, (ii) the PM has analytic solutions to the direct and inverse kinematic problems, and (iii) the PM is of partial motion decoupling property. First, the main topological characteristics, such as the POC, degree-of-freedom, and coupling degree, were calculated for kinematic modeling. Thanks to these properties, the direct and inverse kinematic problems can be readily solved. Further, the conditions of the singular configurations of the PM were analyzed, which corresponds to its partial motion decoupling property.

scholarly journals Development of a Nomogram for Predicting the Occurrence of Symptomatic Intracranial Haemorrhage after Thrombectomy: A Single-Center Retrospective Observational Study

2022 ◽  
Author(s):  
Zequn Li
Keyword(s):  
Risk Factors ◽  
Intracranial Haemorrhage ◽  
Treatment Strategies ◽  
Area Under The Curve ◽  
Intravenous Thrombolysis ◽  
Characteristic Analysis ◽  
Anterior Circulation ◽  
Vessel Occlusion ◽  
Operation Process ◽  
R Project

Abstract Background Symptomatic intracranial haemorrhage (SICH) is a severe and deadly complication in patients with large vessel occlusion (LVO) who receive endovascular treatment (EVT). Recent studies have indicated that many risk factors, including pretreatment scores and the operation process, may be associated with the occurrence of SICH after thrombectomy. This study aims to identify independent risk factors and establish a novel nomogram-based model for patients with anterior LVO to predict the occurrence of SICH after direct thrombectomy or bridge therapy (thrombectomy based on intravenous thrombolysis). Methods Patients with acute ischaemic stroke after EVT to recanalize the blocked artery in anterior circulation were consecutively recruited from November 2017 to March 2019. Baseline information was collected from each patient. These data were subsequently analysed by R Project for Statistical Computing. Results A total of 127 patients with complete data were classified into the training set, among whom 37 patients (29.1%) fulfilled the criteria for SICH. The results of the multivariate analyses showed that NIHSS (P=0.024), ASPECT (P<0.001) and ASITN (P=0.017) scores were independently associated with the occurrence of SICH after thrombectomy. Ultimately, three independent pretreatment predictors were included in the NIHSS/ASPECT/ASITN (NAA) prediction model, and the receiver operating characteristic analysis results showed an area under the curve (AUC) of 0.845 (95% CI=0.763–0.928). The calibration plots showed that the actual observations were consistent with the measured and predicted results of the nomogram. Conclusions In this study, a novel model based on NAA for predicting the occurrence of SICH after thrombectomy in patients with anterior LVO was established and validated internally. The results suggest that this model can help improve perioperative evaluations and individualized treatment strategies.

Shimmy Characteristic Analysis for Steering System of Heavy Mining Dump Trucks

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Lulu Gao ◽  
Fei Ma ◽  
Chun Jin ◽  
Yanjun Huang ◽  
Zhipeng Feng
Keyword(s):  
Hopf Bifurcation ◽  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Steering System ◽  
Parameter Range ◽  
Characteristic Analysis ◽  
Excited Vibration ◽  
Tire Wear ◽  
Dump Trucks ◽  
Pneumatic Suspension

Abstract Tire wear cost accounts for a large proportion of the total cost of heavy mining dump trucks (HMDTs), and the shimmy of the steering system aggravates the tire wear severely. This study proposes a model-based approach to avoid the shimmy of the steering system for such trucks without replacement or destruction of steering structure. First, a five degrees-of-freedom (DOF) shimmy dynamic model of the steering system is established considering the tire lateral dynamics and the nonlinearity of the hydro-pneumatic suspension (HPS). Second, the unstable parameter range of the dynamic model is obtained based on the Lyapunov’s first approximation theorem and Hopf bifurcation theory. The stability analysis results show that the steering system of heavy mining dump trucks is a self-excited vibration system because of the Hopf bifurcation in the unstable parameter range, and this unstable parameter range is greatly affected by the load and the initial pneumatic volume of hydro-pneumatic suspension. In addition, the accuracy of the dynamic is verified by a field test. Therefore, how the load and initial pneumatic volume affect the shimming is analyzed numerically. In other words, how to match the load and initial pneumatic volume is uncovered to avoid the shimmy. For instance, it shows that the shimmy at full load can be avoided at the speed of 30 km/h by charging the initial pneumatic volume of hydro-pneumatic suspension to 14.5 l.

Sign in / Sign up

Export Citation Format

Share Document