Re: Hexapod question

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Tim" <luvindaddy@y...> wrote:
> Hello everyone,
> Can someone answer this stupid question for me????
> What would be the need for a hexapod machine anyway?
> I think it is cool & would probably build one myself if I had the
> time, but can't seem to figure out a use for one??? haha!!
> Any Ideas?
> Thanks, Tim Bostic
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Ray Henry <rehenry@u...>
> wrote:
> >
> > > From: Jon Elson <elson@p...>
> > > Subject: Re: Hexapod question
> > >
> > > Simon M. Arthur wrote:
> > > >I've started building a hexapod on the cheap. Some photos:
> > > >http://www.tinyplanet.com/images/hexapod-portrait-reduced.jpg
> > > >http://www.tinyplanet.com/images/dscf0011-reduced.jpg
> > > >
> > > >I noticed that the platform can be rotated and tilted more or
> less
> > > >freely, even with power going to the steppers. Translational
> movement
> > > > is a lot harder. This makes me think that I misunderstood
> completely
> > > > how a hexapod is supposed to work. I have a universal joint
on
> the
> > > > frame so that the motor can tilt, and another on the platform.
> > > >
> > > >Can this setup be made to work? Why doesn't my hexapod lock the
> > > > platform in place?
> > > >
> > >
> > > The only way a hexapod (Stewart platform) maintains alignment
of
> the
> > > platform
> > > is by controlling the lengths of all 6 struts in a coordinated
> way.
> > > EMC can drive a hexapod, but it doesn't really allow tilting
of
> the
> > > platform. But, you can translate the platform in 3 cartesian
> > > coordinates rather nicely.
> > >
> >
> > Hi Jon, Simon
> >
> > As of a while ago, the EMC motion planner can tilt the hexapod's
> platform.
> > Till Franitza in Stuttgart has been doing this with his desktop
> models.
> > You can see both stepper and servo version photos and a movie at
> >
> > http://www.isw.uni-
stuttgart.de/personen/t_franit/modell/index.html
> >
> > There is some pretty novel work on platform geometry with Model 2
> where
> > three of the the struts interact with the three other struts
rather
> than
> > with the platform itself. This allows for a much larger angle of
> tilt
> > before the system approaches a singularity.
> >
> > If your German conprehension is as poor as mine, there is a
Queen's
> > English version that can be reached by clicking on the Brit flag.
> >
> > Ray