Newsgroups: comp.robotics
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From: hertz@ecf.toronto.edu (Roger B Hertz)
Subject: Re: Fast/Flexible Manipulators
Message-ID: <CHF0Fu.Iov@ecf.toronto.edu>
Sender: news@ecf.toronto.edu (News Administrator)
Organization: University of Toronto, Engineering Computing Facility
References: <2df5p5$f5s@info.epfl.ch> <2dhli2$dco@info.epfl.ch>
Date: Thu, 2 Dec 1993 15:59:53 GMT
Lines: 48

In article <2dhli2$dco@info.epfl.ch>,
Philippe Guglielmetti  <guglielmetti@elia.epfl.ch> wrote:
>
[some deletions]
>... The first consequence of this is that
>forward kinematics has no closed form in the general case while inverse
>kinematics always has a closed form. 
            ^^^^^^

While this can be said for 6 DOF // manipulators, it is not true in general
for 3 DOF // manipulators.  Only in very special cases will a 3 DOF //
mechanism have a closed form IK solution.  A closed form solution will not
exist for the general case where the translation and rotation of the 
end-effector are coupled (which really throws a wrench into the works).

[more deletions, including some good refs on // manips]

Another recent reference from some work in the US is:

	Kevin Cleary & Thurston Brooks, "Kinematic Analysis of a Novel 
	6-DOF Parallel Manipulator",  Proceedings of the IEEE International
	Robotics and Automation Conference - 1993, pp. 708-713.

and from Japan:

	Funabashi, Horie, Kubota & Takeda, "Development of Spatial 
	Parallel Manipulators with Six Degrees of Freedom", JSME 
	International Journal, Series III, Vol 34, No 3, 1991, 
	pp. 382-387.

just to name a few.

I have seen several of the parallel manipulators mentioned in Europe,
and IMHO, they have an extremely high potential to be used extensively
in industry.  One challenge that exists for researchers and designers,
however, is to overcome the problem of a much reduced workspace
volume.  The resulting robot mechanism may not be flexible, but the
resulting robot system may not be "flexible" either. ;-)

>
>Philippe Guglielmetti Institut d'Automatique EPFL Lausanne
>(philippe.guglielmetti@ia.epfl.ch)


-- 
hertz@ecf.toronto.edu
University of Toronto                               Ph: (416) 667-7744
Institute for Aerospace Studies                    Fax: (416) 667-7799
