Singularity-invariant leg substitutions in pentapods

6 páginas, 5 figuras, 4 tablas.-- Trabajo presentado a la IROS 2010 celebrada en Taipei (Taiwan) del 18 al 22 de Octubre.A pentapod is usually defined as a 5-degree-of-freedom fully-parallel manipulator with an axial spindle as moving platform. This kind of manipulators have revealed as an interesting alternative to serial robots handling axisymmetric tools. Their particular geometry permits that, in one tool axis, inclination angles of up to 90 degrees are possible thus overcoming the orientation limits of the classical Stewart platform.This work has been partially supported by the Spanish Ministry of Education and Innovation, under the I+D project DPI2007-60858.Peer reviewe

Self-motions of pentapods with linear platform

We give a full classification of all pentapods with linear platform possessing a self-motion beside the trivial rotation about the platform. Recent research necessitates a contemporary and accurate re-examination of old results on this topic given by Darboux, Mannheim, Duporcq and Bricard, which also takes the coincidence of platform anchor points into account. For our study we use bond theory with respect to a novel kinematic mapping for pentapods with linear platform, beside the method of singular-invariant leg-rearrangements. Based on our results we design pentapods with linear platform, which have a simplified direct kinematics concerning their number of (real) solutions.Comment: 28 pages, 5 figure

New geometric approaches to the singularity analysis of parallel platforms

Presentado al Workshop de Robótica Experimental celebrado en Sevilla del 28 al 29 de noviembre de 2011.In general, rearranging the legs of a Stewart-Gough platform, i.e., changing the locations of its leg attachments, modifies the platform singularity locus in a rather unexpected way. Nevertheless, some leg rearrangements have been recently found to leave singularities invariant. In this work, a summary of the some of such singularity-invariant leg rearrangements are presented, and their practical consequences are illustrated with several examples including well-known architectures.Peer Reviewe

New geometric approaches to the singularity analysis of parallel platforms

In general, rearranging the legs of a Stewart- Gough platform, i.e., changing the locations of its leg attachments, modifies the platform singularity locus in a rather unexpected way. Nevertheless, some leg rearrangements have been recently found to leave singularities invariant. In this work, a summary of the some of such singularity-invariant leg rearrangements are presented, and their practical consequences are illustrated with several examples including well-known architectures.Postprint (author’s final draft

New geometric approaches to the analysis and design of Stewart-Gough platforms

In general, rearranging the legs of a Stewart-Gough platform, i.e., changing the locations of its leg attachments, modifies the platform singularity locus in a rather unexpected way. Nevertheless, some leg rearrangements have been recently found to leave singularities invariant. Identification of such rearrangements is useful not only for the kinematic analysis of the platforms, but also as a tool to redesign manipulators avoiding the implementation of multiple spherical joints, which are difficult to construct and have a small motion range. In this study, a summary of these singularity-invariant leg rearrangements is presented, and their practical implications are illustrated with several examples including well-known architectures.The authors gratefully acknowledge funding from the Generalitat de Catalunya through the Robotics group (SRG0155).Peer Reviewe

Advances in Robot Kinematics : Proceedings of the 15th international conference on Advances in Robot Kinematics

International audienceThe motion of mechanisms, kinematics, is one of the most fundamental aspect of robot design, analysis and control but is also relevant to other scientific domains such as biome- chanics, molecular biology, . . . . The series of books on Advances in Robot Kinematics (ARK) report the latest achievement in this field. ARK has a long history as the first book was published in 1991 and since then new issues have been published every 2 years. Each book is the follow-up of a single-track symposium in which the participants exchange their results and opinions in a meeting that bring together the best of world’s researchers and scientists together with young students. Since 1992 the ARK symposia have come under the patronage of the International Federation for the Promotion of Machine Science-IFToMM.This book is the 13th in the series and is the result of peer-review process intended to select the newest and most original achievements in this field. For the first time the articles of this symposium will be published in a green open-access archive to favor free dissemination of the results. However the book will also be o↵ered as a on-demand printed book.The papers proposed in this book show that robot kinematics is an exciting domain with an immense number of research challenges that go well beyond the field of robotics.The last symposium related with this book was organized by the French National Re- search Institute in Computer Science and Control Theory (INRIA) in Grasse, France

The design and analysis of a novel 5 degree of freedom parallel kinematic manipulator.

Masters Degree. University of KwaZulu-Natal, Durban.Abstract available in PDF

Singularity-invariant leg substitutions in pentapods

A pentapod is usually defined as a 5-degree-offreedom fully-parallel manipulator with an axial spindle as moving platform. This kind of manipulators have revealed as an interesting alternative to serial robots handling axisymmetric tools. Their particular geometry permits that, in one tool axis, inclination angles of up to 90 degrees are possible thus overcoming the orientation limits of the classical Stewart platform. This paper presents a solution to the problem of finding those changes in the location of the leg attachments of a pentapod that leave its singularity locus invariant. Although the solution to this problem does not provide a fully characterization of the singularities, it provides a lot of insight into its nature. It is shown, for example, that there are four different architectures for a pentapod with a completely different behavior from the point of view of their singularities. The kinematics of pentaponds with coplanar attachments at the fixed base has previously been studied as rigid subassemblies of a Stewart platforms. In this paper, we treat the general case in which the base attachments are arbitrarily located in 3D space