scholarly journals Degree-of-Freedom Analysis and Structural Synthesis of a Class of Host–Parasite Multi-Loop Mechanisms

2021 ◽  
Author(s):  
Wei Wei ◽  
Geyu Dong
Keyword(s):  
Machine Tools ◽  
Degrees Of Freedom ◽  
Distribution Patterns ◽  
Degree Of Freedom ◽  
Numerical Control ◽  
Serial Connection ◽  
In Series ◽  
P Type ◽  
S Model ◽  
Host Parasite

Abstract The method of analyzing the mechanism in series, parallel and hybrid modes can no longer meet the requirements of analyzing multi-loop mechanisms (MLMs), especially multi-loop mechanisms with passive degrees of freedom(P-DOFs).This study presents an approach to analyzing sub-degree-of-freedom (sub-DOF) relations in a class of MLMs with P-DOFs (P-DOFs) as well as structurally synthesizing these mechanisms. First,the DOFs of mechanisms with P-DOFs are decomposed and combined,and two methods—multi-loop serial connection and multi-loop stacking—are formulated to establish MLMs with P-DOFs.Second, a DOF space (DOF-S) model is generated.Host–parasite (H–P) MLMs are proposed, and various types of parasitism are analyzed. Finally, various DOF distribution patterns in H–P MLMs are analyzed based on real-world examples. The results show the following. H–P mechanisms are a class of MLMs with P-DOFs. For an H–P mechanism, its DOFs can be longitudinally and centrally, transversely and centrally, or comprehensively optimally distributed in the DOF-S by selecting a suitable type of parasitism. The H–P-type palletizing robot prototype developed in this study is able to self-balance. This demonstrates that the comprehensive optimization of DOF distribution is effective. This study enriches the theoretical knowledge on MLMs, which are extensively applied in fields such as aerospace, industrial robotics, and numerical-control machine tools.

A Novel 5-DOF NC Serial-Parallel Machine Tool and its Position Analysis

2010 ◽  
Vol 431-432 ◽  
pp. 355-360
Author(s):  
Hong Jun San ◽  
Shi Sheng Zhong ◽  
Zhi Xing Wang
Keyword(s):  
Machine Tool ◽  
Analytical Method ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Structural Characteristics ◽  
Parallel Machine ◽  
Numerical Control ◽  
Forward Solution ◽  
In Series ◽  
Parallel Machine Tool

In this paper, a novel 5 degrees-of-freedom (DOF) numerical control (NC) serial-parallel machine tool is proposed. It can provide 3 translational DOF and 2 rotational DOF. The proposed mechine tool is composed of a 2-TPR/2-TPS special 4-DOF parallel mechanism in series with a rotatable component. The structure of this machine tool is simple. The machine tool can process the workpieces which have complex surfaces.The structural characteristics of this machine tool is introduced. The position inverse solution of this machine tool is deduced by analytical method and the position forward solution of this machine tool is achieved by numerical method.

scholarly journals Coupled tribo-dynamic modelling of linear guideways for high precision machining application

2020 ◽  
pp. 135065012091988
Author(s):  
Parivash Soleimanian ◽  
Mahdi Mohammadpour ◽  
Hamid Ahmadian
Keyword(s):  
Machine Tools ◽  
Degrees Of Freedom ◽  
Thickness Distribution ◽  
Dynamic Modelling ◽  
Degree Of Freedom ◽  
Precision Machining ◽  
Lubricated Contacts ◽  
Loading Direction ◽  
And Performance ◽  
Coupled Solution

Linear guideways play a crucial role in determining precision of machine tools. Understanding their dynamic response is essential for objectively controlling their behavior and performance in operation. Due to highly loaded lubricated contacts, mixed-elastohydrodynamic regime is dominant. The mixed-elastohydrodynamic film maintains the coupling between horizontal degree of freedom (feed velocity) and vertical degree of freedom (loading direction). This paper presents a novel tribo-dynamic solution for linear guideways, taking in to account the lubricant effects and coupling between horizontal and vertical degrees of freedom. An analytical tribology model is used implicitly within the dynamic model. For in-depth tribological quantities including pressure and film thickness distribution, an explicit full numerical solution for mixed-elastohydrodynamic is utilized. Results show that the coupled solution of vertical and horizontal degrees of freedom taking in to account lubricated contacts is essential. It is shown that at moderate and light loads, the effect of this coupling and presence of lubricant is more pronounced.

Development of Five-Axis Machine Tool Cutting Simulation System with Nonorthogonal Linear Axis

2011 ◽  
Vol 314-316 ◽  
pp. 1587-1590
Author(s):  
Chen Hua She ◽  
Kai Sheng Li ◽  
Yueh Hsun Tsai
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Degrees Of Freedom ◽  
Simulation System ◽  
Numerical Control ◽  
Cutting Simulation ◽  
Nc Code ◽  
Tool Axis ◽  
Tool Cutting ◽  
Five Axis

Five-axis machine tools with two additional rotational degrees of freedom provide more flexibility in tilting the tool axis to various orientations than conventional three-axis machine tools do, subsequently increasing the cutting efficiency and avoiding tool collision against a workpiece. Also, the risk of programming error can be avoided by simulating the five-axis Numerical Control (NC) code before real machining. This work presents a five-axis machine tool cutting simulation system with a nonorthogonal linear axis configuration. A window-based cutting system written by Borland C++ Builder and OpenGL is also developed based on the kinematics model of the proposed machine tool. Furthermore, implementing and verifying the five-axis NC code demonstrates the effectiveness of the proposed scheme.

Kinematics of a Hybrid Series-Parallel Manipulation System

1989 ◽  
Vol 111 (2) ◽  
pp. 211-221 ◽  
Author(s):  
K. J. Waldron ◽  
M. Raghavan ◽  
B. Roth
Keyword(s):  
Degrees Of Freedom ◽  
Joint Space ◽  
Degree Of Freedom ◽  
Micro Manipulator ◽  
In Series ◽  
Basic Transformation ◽  
Motion Characteristics ◽  
Six Degree Of Freedom ◽  
Three Degree Of Freedom ◽  
Force Decomposition

In this paper we first derive the coordinate transformations associated with a three-degree-of-freedom in-parallel-actuated micro-manipulator. Then we combine these results with the transformations associated with an in-series three-axis wrist on which the in-parallel micro-manipulator is mounted. The results are the basic transformation equations between joint-space position variables and end-effector (or task space) position variables for a hybrid series/parallel six-degree-of-freedom manipulator system. This structural combination results in a manipulator which exhibits desirable fine and gross motion characteristics as both a stand-alone device or as a sub-system of a more complex system with redundant degrees of freedom. The forward and inverse position kinematics and rate and force decomposition for this hybrid six-degree-of-freedom linkage are presented.

scholarly journals Path-planning of a hybrid parallel robot using stiffness and workspace for foot rehabilitation

2018 ◽  
Vol 10 (1) ◽  
pp. 168781401775415 ◽  
Author(s):  
Alireza Rastegarpanah ◽  
Hamid Rakhodaei ◽  
Mozafar Saadat ◽  
Mohammad Rastegarpanah ◽  
Naresh Marturi ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Degree Of Freedom ◽  
Position Vector ◽  
Parallel Mechanisms ◽  
Moving Platforms ◽  
Maximum Stiffness ◽  
In Series ◽  
Applied Forces

Stiffness is one of the important parameters for estimating the performance of hybrid parallel robots as it is not constant throughout its workspace. The aim of this study is to provide an optimum path based on maximum stiffness within the workspace of a 9-degree-of-freedom hybrid parallel mechanism configuration, which includes nine linear actuators connecting one stationary and two moving platforms in series. The proposed robot is designed for ankle rehabilitation, where accurate and precise movement of lower extremities is required. The design takes advantage of two important characteristics of parallel robots: stiffness and workspace. The proposed methodology to determine the stiffness of hybrid robot in three single axes is based on calculation of position vector of each actuator in any particular pose, by considering the inverse kinematics of the system, in order to obtain the magnitude and direction of the applied forces. The results obtained from the workspace calculations have been compared with those of two standard parallel mechanisms including a 6-degree-of-freedom hexapod and a tripod with 3 degrees of freedom. The stiffness of the robot has been calculated in simulation and then compared with those of a developed prototype hybrid model in two different case studies.

scholarly journals Influence Structures of The Machine Tools on Roughness in Turning

2020 ◽  
Vol 14 ◽  
Keyword(s):  
Surface Quality ◽  
Machine Tools ◽  
Numerical Control ◽  
Elastic Behaviour ◽  
Machined Surface ◽  
Good Surface ◽  
Machined Surface Quality ◽  
Finished Surface ◽  
In Series

The final quality of machining is directly a function of the type of machine used. The geometrical and micro quality geometrical of finished surface are one of the principal goals of machining. During the operation of turning, in particular, the elastic behaviour of the pin controls the surface quality machined. To say that the rigidity of the machine must be largest possible is not sufficient. The design of the axes of movement of the machine must take account of the effects static, kinematics, dynamic of the mass. The rigidity and the conditions of maintenance by the stages must be qualified in comparison with the results sought in term of machined surface quality. To characterize the effect of the vibrations of the machine tools on the quality of the machined surfaces a study was undertaken on two different lathes, a conventional turn and a turn with numerical control. The results of roughness show that the machine tool exploits a great role the machined surface quality. The rigidity of the machine and its capacities damping are prevalent factors to have a good surface quality.To this end the choice of a thing rigid and damping tool is essential for any trial run and any industrial machining in series.

scholarly journals Design and Calibration of a Hall Effect System for Measurement of Six-Degree-of-Freedom Motion within a Stacked Column

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3740
Author(s):  
Olafur Oddbjornsson ◽  
Panos Kloukinas ◽  
Tansu Gokce ◽  
Kate Bourne ◽  
Tony Horseman ◽  
...  
Keyword(s):  
Hall Effect ◽  
Degrees Of Freedom ◽  
Reactor Core ◽  
Degree Of Freedom ◽  
Life Extension ◽  
Scale Model ◽  
Design Development ◽  
Seismic Safety ◽  
Six Degrees Of Freedom ◽  
Six Degree Of Freedom

This paper presents the design, development and evaluation of a unique non-contact instrumentation system that can accurately measure the interface displacement between two rigid components in six degrees of freedom. The system was developed to allow measurement of the relative displacements between interfaces within a stacked column of brick-like components, with an accuracy of 0.05 mm and 0.1 degrees. The columns comprised up to 14 components, with each component being a scale model of a graphite brick within an Advanced Gas-cooled Reactor core. A set of 585 of these columns makes up the Multi Layer Array, which was designed to investigate the response of the reactor core to seismic inputs, with excitation levels up to 1 g from 0 to 100 Hz. The nature of the application required a compact and robust design capable of accurately recording fully coupled motion in all six degrees of freedom during dynamic testing. The novel design implemented 12 Hall effect sensors with a calibration procedure based on system identification techniques. The measurement uncertainty was ±0.050 mm for displacement and ±0.052 degrees for rotation, and the system can tolerate loss of data from two sensors with the uncertainly increasing to only 0.061 mm in translation and 0.088 degrees in rotation. The system has been deployed in a research programme that has enabled EDF to present seismic safety cases to the Office for Nuclear Regulation, resulting in life extension approvals for several reactors. The measurement system developed could be readily applied to other situations where the imposed level of stress at the interface causes negligible material strain, and accurate non-contact six-degree-of-freedom interface measurement is required.

scholarly journals Study of Machining of Gears with Regular and Modified Outline Using CNC Machine Tools

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2913
Author(s):  
Rafał Gołębski ◽  
Piotr Boral
Keyword(s):  
Machine Tools ◽  
Coordinate Measuring Machine ◽  
Optical Microscope ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Cnc Milling ◽  
Cnc Machine ◽  
Cylindrical Gears ◽  
Measuring Machine ◽  
Five Axis

Classic methods of machining cylindrical gears, such as hobbing or circumferential chiseling, require the use of expensive special machine tools and dedicated tools, which makes production unprofitable, especially in small and medium series. Today, special attention is paid to the technology of making gears using universal CNC (computer numerical control) machine tools with standard cheap tools. On the basis of the presented mathematical model, a software was developed to generate a code that controls a machine tool for machining cylindrical gears with straight and modified tooth line using the multipass method. Made of steel 16MnCr5, gear wheels with a straight tooth line and with a longitudinally modified convex-convex tooth line were machined on a five-axis CNC milling machine DMG MORI CMX50U, using solid carbide milling cutters (cylindrical and ball end) for processing. The manufactured gears were inspected on a ZEISS coordinate measuring machine, using the software Gear Pro Involute. The conformity of the outline, the tooth line, and the gear pitch were assessed. The side surfaces of the teeth after machining according to the planned strategy were also assessed; the tests were carried out using the optical microscope Alicona Infinite Focus G5 and the contact profilographometer Taylor Hobson, Talysurf 120. The presented method is able to provide a very good quality of machined gears in relation to competing methods. The great advantage of this method is the use of a tool that is not geometrically related to the shape of the machined gear profile, which allows the production of cylindrical gears with a tooth and profile line other than the standard.

scholarly journals Cysteine-Free Proteins in the Immunobiology of Arthropod-Borne Diseases

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
J. Santiago Mejia ◽  
Erik N. Arthun ◽  
Richard G. Titus
Keyword(s):  
Plasmodium Falciparum ◽  
Amino Acid ◽  
Distribution Patterns ◽  
Structural Features ◽  
Structure And Function ◽  
Cysteine Residues ◽  
Distribution Analysis ◽  
And Function ◽  
Abundance And Distribution ◽  
Host Parasite

One approach to identify epitopes that could be used in the design of vaccines to control several arthropod-borne diseases simultaneously is to look for common structural features in the secretome of the pathogens that cause them. Using a novel bioinformatics technique, cysteine-abundance and distribution analysis, we found that many different proteins secreted by several arthropod-borne pathogens, includingPlasmodium falciparum, Borrelia burgdorferi, and eight species of Proteobacteria, are devoid of cysteine residues. The identification of three cysteine-abundance and distribution patterns in several families of proteins secreted by pathogenic and nonpathogenic Proteobacteria, and not found when the amino acid analyzed was tryptophan, provides evidence of forces restricting the content of cysteine residues in microbial proteins during evolution. We discuss these findings in the context of protein structure and function, antigenicity and immunogenicity, and host-parasite relationships.

The thermodynamics of intracrystalline sorption I. Models of the sorbed state

1956 ◽  
Vol 234 (1196) ◽  
pp. 24-34 ◽  
Keyword(s):  
Mobile Phase ◽  
Degrees Of Freedom ◽  
Degree Of Freedom ◽  
Translational Degree ◽  
Sorbate Concentration ◽  
The Ideal

Three basic models of the intracrystalline sorbed state are discussed: a localized phase, a mobile phase possessing two translational degrees of freedom, and a mobile phase with one translational degree of freedom. The isotherm and entropy of each of these models have been investigated for the ideal phase, and where possible the influence of sorbate-sorbate interactions has been considered. Expressions for the molal and differential entropies of each model are given as a function of sorbate concentration. The method of comparing theoretical isotherms and entropies with experimental observations is outlined.

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