Reconfiguration Analysis of a Fully Reconfigurable Parallel Robot

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Allan Daniel Finistauri ◽  
Fengfeng (Jeff) Xi
Keyword(s):  
Comparative Study ◽  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Passive State ◽  
Limited Mobility ◽  
Six Degrees Of Freedom ◽  
Revolute Joints ◽  
Six Degree Of Freedom ◽  
The Comparative Study ◽  
Selection Of

This paper presents a new method for the combined topological and geometric reconfiguration of a parallel robot to achieve task-based reconfiguration. Using the existing structure of a six degree-of-freedom (DOF) parallel robot, reconfiguration to limited mobility modes, a configuration with less than six degrees-of-freedom, can be achieved easily without the need to remove branches from the robot structure. Branch modules are instead, reconfigured from an unconstrained-active to a constrained-passive state by means of hybrid active/passive motors and reconfigurable universal-to-revolute joints. In doing so, the robot is capable of assuming a configuration in which the number of task-based degrees-of-freedom match the number of controllable actuators within the robot structure. The selection of branch modules for reconfiguration is independent of the limited mobility mode required and leads to multiple isomorphic configurations. A comparative study is thus needed to understand not only the implication of morphing, but also the capabilities of the reconfigured robot. For this purpose, a branch-based mobility analysis is performed and isomorphic configurations are identified. These isomorphic configurations are then compared based on their workspace and kinematic capabilities for which a parametric kinematic constraint formulation is developed. The comparative study evaluates the abilities of each configuration and is used for guidance in selecting an appropriate configuration for a particular task. The developed tools can also be used for design evaluation purposes.

A Nonlinear Six Degree-of-Freedom Axle and Body Combination Roll Model for Heavy Trucks’ Directional Stability

2004 ◽  
Author(s):  
Nuraj I. Rajapakse ◽  
Gemunu S. Happawana
Keyword(s):  
Degrees Of Freedom ◽  
Phase Portraits ◽  
Six Degrees Of Freedom ◽  
Directional Stability ◽  
Heavy Trucks ◽  
Inclination Angles ◽  
Heavy Truck ◽  
Six Degree Of Freedom ◽  
Limiting Values ◽  
Selection Of

Six degrees of freedom nonlinear suspension roll model of a heavy truck axle unit is presented. The model includes the effects of nonlinear tire damping, road inclination angle, and variation of suspension angles. The roll model parametric analysis provides the influence of various geometric truck parameters that are important to the designer in stability viewpoint. Many of the important parameters such as nonlinear tire coefficients, road and suspension inclination angles, and some of their limiting values for stability are also discussed to facilitate the selection of proper actuators and sensors for automation. The dynamic stability of the axle unit is illustrated using parameters dependent phase portraits. These phase portraits provide qualitative information on truck’s directional stability.

Inverse kinematics of six-degree of freedom “general” and “special” manipulators using symbolic computation

Robotica ◽  
1994 ◽  
Vol 12 (5) ◽  
pp. 421-430 ◽  
Author(s):  
C. Mavroidis ◽  
F. B. Ouezdou ◽  
P. Bidaud
Keyword(s):  
Trivial Solution ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Six Degrees Of Freedom ◽  
Industrial Manipulator ◽  
Revolute Joints ◽  
Closure Equation ◽  
Inverse Kinematics Problem ◽  
A Chain ◽  
Six Degree Of Freedom

SUMMARYThis paper presents an algorithm that solves the inverse kinematics problem of all six degrees of freedom manipulators, “general” or “special”. A manipulator is represented by a chain of characters that symbolizes the position of prismatic and revolute joints in the manipulator and the special geometry that may exist between its joint axes. One form of the loop closure equation is chosen and the Raghavan and Roth method is used to obtain symbolically a square matrix. The determinant of this matrix yields the characteristic polynomial of the manipulator in one of the kinematic variables. As an example of the use of this algorithm we present the solution to the inverse kinematics problem of the GMF Arc Mate welding manipulator. In spite of its geometry, this industrial manipulator has a non-trivial solution to its inverse kinematics problem.

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 Public Policies for Procurement under COVID19

2021 ◽  
Vol 1 (3) ◽  
pp. 9-36
Author(s):  
Luís Valadares Tavares ◽  
Pedro Arruda
Keyword(s):  
Comparative Analysis ◽  
Comparative Study ◽  
Public Procurement ◽  
Public Policies ◽  
European Directives ◽  
Public Markets ◽  
The Public ◽  
Public Contracting ◽  
The Comparative Study ◽  
Selection Of

Public procurement is a main issue in the frontline of Governments fighting COVID 19 pandemic as the need for additional and urgent acquisitions as well as the need to consolidate the supply chains and to promote sustainable and innovative procurement have been a source of deep changes and main challenges disturbing public markets and invalidating several assumptions of the traditional public contracting. In this paper, the development of appropriate public policies to cope with these challenges is studied following the approach suggested by several authors and including four stages: a Stage on Facts and Issues where the main challenges and conditions are studied, the Options Stage to describe which polices and procedures can be adopted, a Values Stage stating the main values to be pursued and, finally, a Policies Stage including the selection of the recommended policies. The analysis of the challenges and facts includes the study of a taxonomy of short and longer term needs and the available options are based on the comparative study of procedures ruled by the European Directives on Public Procurement approved on 2014. The major values to be respected include the principle of competition which is a major institutional principle of the European Treaty and of the Directives as well as the goal of promoting sustainable and innovative public procurement. Several indicators are suggested to describe the application of the public procurement policies adopted across EU and their comparative analysis is presented using the TED data for contracts concerning COVID 19. The case of Portugal is discussed and final remarks about the recommended public policies are also included herein.

scholarly journals Application of a Multifunctional Additive in Cosmetic Preparations for Safe Preservation

2019 ◽  
Vol 70 (7) ◽  
pp. 2429-2433
Author(s):  
Anca Maria Juncan ◽  
Luca Liviu Rus ◽  
Veronica Isabela Craciun ◽  
Andreea Loredana Vonica Tincu ◽  
Claudiu Morgovan
Keyword(s):  
Comparative Study ◽  
Challenge Test ◽  
Multifunctional Additive ◽  
Methyl Paraben ◽  
Propyl Paraben ◽  
Proven Efficacy ◽  
Cosmetic Formulation ◽  
The Comparative Study ◽  
S Application ◽  
Selection Of

The aim of this study is represented by the description and the selection of an alternative preservative complex, it�s application in the development and formulation of a moisturizer and the comparative study of the efficacy of the cosmetic formulation, versus a traditional preserved cosmetic cream. For an adecvate preservation of the moisturizing cream there was used comparatively, the alternative preservation system Dermosoft LP (Caprylyl Glycol, Glycerin, Glyceryl Caprylic, Phenylpropanol), and the traditional preservative Salinip (Phenoxyethanol, Methyl Paraben, Propyl Paraben, Ethyl Paraben, Butyl Paraben, Isobutyl Paraben). Dermosoft LP has comparable effects to traditional preservatives, and proven efficacy by microbiological Challenge test.

Construction of a Six-Degrees-of-Freedom Parallel Manipulator With Three Planarly Actuated Links

1996 ◽  
Author(s):  
Ronen Ben-Horin ◽  
Moshe Shoham
Keyword(s):  
Parallel Manipulator ◽  
High Performance ◽  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Simple Design ◽  
Output Link ◽  
Coordinated Motion ◽  
Six Degrees Of Freedom ◽  
Work Volume ◽  
New Type

Abstract The construction of a new type of a six-degrees-of-freedom parallel robot is presented in this paper. Coordinated motion of three planar motors, connected to three fixed-length links, produces a six-degrees-of-freedom motion of an output link. Its extremely simple design along with much larger work volume make this high performance-to-simplicity ratio robot very attractive.

A Family of 3-DOF Translational Parallel Manipulators1

2003 ◽  
Vol 125 (2) ◽  
pp. 302-307 ◽  
Author(s):  
Marco Carricato ◽  
Vincenzo Parenti-Castelli
Keyword(s):  
Degrees Of Freedom ◽  
Translational Motion ◽  
Parallel Manipulators ◽  
Geometric Interpretation ◽  
The Other ◽  
Six Degrees Of Freedom ◽  
Revolute Joints ◽  
Rotational Degrees Of Freedom

This article addresses parallel manipulators with fewer than six degrees of freedom, whose use may prove valuable in those applications in which a higher mobility is uncalled for. In particular, a family of 3-dof manipulators containing only revolute joints or at the most revolute and prismatic ones is studied. Design and assembly conditions sufficient to provide the travelling platform with a pure translational motion are determined and two sub-families that fulfill the imposed constraint are found: one is already known in the literature, while the other is original. The new architecture does not exhibit rotation singularities, i.e., configurations in which the platform gains rotational degrees of freedom. A geometric interpretation of the translation singularities is provided.

General Mathematical Model of Multi-Arm Cooperating Robots With Elastic Interconnection at the Contact

1997 ◽  
Vol 119 (4) ◽  
pp. 707-717 ◽  
Author(s):  
Milovan Z˘ivanovic´ ◽  
Miomir Vukobratovic´
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Dynamic Environment ◽  
Six Degrees Of Freedom ◽  
General Mathematical Model ◽  
Cooperating Robots ◽  
Six Degree Of Freedom ◽  
Physical Phenomena ◽  
First Time ◽  
Object Dynamic

The procedure of modeling and the complete general form mathematical model of manipulators with six degrees of freedom in cooperative work are presented in the paper, together with the solution of undefiniteness problem with respect to force distribution. For the first time, a system of active spatial six-degree-of-freedom mechanisms elastically interconnected with the object (dynamic environment) is modeled. The reason for the emergence of the undefiniteness problem with respect to force is explained and the procedure for solving this problem given. Unlike the approaches given in the available literature, the undefiniteness problem with respect to force is solved in accordance with physical phenomena. The modeling procedure is illustrated by a simplified example.

A Parallel Six Degrees-of-Freedom Inflatable Robot

2000 ◽  
Author(s):  
Patricia Ben-Horin (Dombiak) ◽  
Moshe Shoham ◽  
Gershon Grossman
Keyword(s):  
Path Planning ◽  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Six Degrees Of Freedom ◽  
Robot Architecture

Abstract A new structure of a six degrees-of-freedom robot is described in this paper. The robot presents two new features: three inflatable links that constitute the robot structure and parallel robot architecture with large workspace. These features result in a lightweight and easy to deploy robot. The structure, kinematics and path planning of the experimental robot are presented.

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