Alt-BEAM Archive
Message #03188
To: "van Zoelen, Bram SSI-TSEA-352" Bram.A.A.vanZoelen@is.shell.com,
From: Dennison dennlill@buffnet.net
Date: Tue, 11 May 1999 08:03:57 -0400
Subject: [alt-beam] Re: a useless idea
Tada! Thats what I've been talking about! My robot for chiu's contest does
exactly that. It takes a little tuning to get right, (Which I'm still
working on) so that the bot doesn't just jiggle, but it indeed 'hops'
places, and twards the light. Geez, I built a working one of these last
summer and posted to the list and no one was interested! Now people see what
I was talking about. I knew someone would connect up the idea of inertial
positioning to an inertial drive.
cheers!
Dennison
Hi,
Why not go a little step further. Make a light seeking head on a light
frame.
This will position the top of the frame towards the light. Add to the frame
that can rotate the '¡nertial drive' but not in the horizontal plane but at
the vertical plane. If the drive kickes then the bot will hop towards the
light.
Some sort of kangaroo bot i guess.
Bram
Robotic pages
http://www.xs4all.nl/~vsim
> ----------
> From: Wilf Rigter[SMTP:Wilf.Rigter@powertech.bc.ca]
> Reply To: Wilf Rigter
> Sent: Tuesday, May 11, 1999 2:58 AM
> To: 'Dennison'
> Cc: beam@corp.sgi.com
> Subject: RE: a useless idea
>
> Hello Dennison,
>
> I guess there is inertia in everything especially my brain. I reread your
> post and yes there is some similarity but I would refer to your idea as
> "wobble"drive and Wouters idea as "inertial rotation" or "inertial
> positioning" You proposed your idea for locomotion which is quite
> different
> from simple phototropic "inertial rotation".
> Your original idea for inertial locomotion has much merit, and was no
> doubt
> itself based on prior ideas (all the way back to Newton's apple and then
> some) and like all other ideas/inventions on this list: grist for the
> "mill
> of learning" and that is what BEAM evolution is about.
>
> regards
>
> Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> tel: (604)590-7493
> fax: (604)590-3411
>
> > -----Original Message-----
> > From: Dennison [SMTP:dennlill@buffnet.net]
> > Sent: Monday, May 10, 1999 4:39 PM
> > To: Wilf Rigter; beam@corp.sgi.com
> > Subject: Re: a useless idea
> >
> > Actually, that's the same Idea that I use in my bot for chiu's contest.
> I
> > don't know if anyone got either other posting, but my bot uses the same
> > idea
> > of inertia, or momentum, for locomotion. Using one motor, and a ordinary
> > bicore head, with a little modification, I have a bot that is
> phototropic.
> > The head not only points twards the light, but it moves twards it.
> > Basically
> > the head swings a large weight around (not all the way around) a ceritan
> > amount, about 260 degres or so, and it produces a forward motion from
> the
> > angular momentum.
> >
> > When the head swings and reverses direction, you get a tangential
> > acceleration found by
> >
> > Acceleration-tangential = Radius * AngularAcceleration
> >
> > From that we can calculate a rough idea of the force, given the weight
> of
> > our head, and the radius of the counterweight.
> >
> > Force=Mass(weight)*Acceleration(tangential)
> >
> > But what about the inertia?
> >
> > Force = Mass * Acceleration
> >
> > so then
> >
> > Force = Mass * Radius * Angular Acceleration
> >
> > But we need some more befor we can go on, Torque is Radius times the
> force
> > or
> >
> > Torque=radisu*Force and we know what force is, so we get:
> >
> > Torque = Mass * Radius^2 * Angular Acceleration (mr^2 represents the
> > rotational inertia)
> >
> > To find the total torque, supposidly we need to calculate the torque for
> > every single particle. Atoms, quarks, etc.. But thats unnessesary for
> our
> > purposes.
> >
> > So the Momenet of Inertia for our HEAD or mobile, or etc.. is
> >
> > Inertia = Sumation( mass *radius^2)
> >
> > Actually this is a little simplified. For a Bicore head, or the mobile
> > described, the shape of our device isn't a thin hoop, which the above
> > formula works for. The formula for the momenet of inertia for our
> devices
> > is: (1/3)Mass*Radius^2
> >
> > When building a bot like this, this really isn't too important to know,
> > although you should understand it to produce good results, if you want
> > more,
> > any good physics book will tell you how. There's also a bunch more to
> it.
> > Like calculating the friction between the head device and it's
> environment
> > and such. But it's fun stuff.
> >
> > Dennison
> >
> >
> >
> >
> >
> > >Inertial positioning!
> > >
> > >Useless???? You have practically invented a phototropic MOBILE ! This
> is
> > of
> > >course a brilliant (although perhaps not entirely new) idea ! A low
> > >friction bearing would permit the same mechanism to be used for
> standard
> > >head applications with a tripod support. While interesting for
> > >head/bot/mobiles that turn with respect to a fixed reference this idea
> is
> > >much more practical when used in referenceless application: Most
> > effective
> > >in zero gravity applications (in space), it can also be used for zero
> > >bouancy applications in the air for example with helium filled
> spherical
> > >"AIRHEAD" or under water for example a cylindrical shaped or spherical
> 1
> > or
> > >2 DOF "AQUAHEAD" suspended in a transparent tank (aquarium) could use
> > this
> > >phototropic inertial positioning idea to follow a light.
> > >
> > >enjoy
> > >
> > >
> > > Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> > > tel: (604)590-7493
> > > fax: (604)590-3411
> > >
> > >> -----Original Message-----
> > >> From: Wouter Brok [SMTP:w.j.m.brok@stud.tue.nl]
> > >> Sent: Sunday, May 09, 1999 11:33 PM
> > >> To: beam@corp.sgi.com
> > >> Subject: a useless idea
> > >>
> > >> Hello,
> > >>
> > >> Yesterday I thought up an weird hanging robot (well, you can hardly
> > call
> > >> it
> > >> a robot, but it moves). I attached a scanned drawing to make things
> > more
> > >> clear, and I will write down a couple of remarks below. Maybe
> somebody
> > >> thinks it is a funny thing to make (be my guest ... I would like to
> > hear
> > >> about it) or maybe somebody can make a greater idea from it (... I
> > would
> > >> like to hear about that too).
> > >>
> > >> In a hanging box (which could be made with PCB, with the components
> on
> > the
> > >> outside) a motor is fixed with a weight attached to the axis. When
> the
> > >> motor turns the box will turn around the line of the wire to which it
> > is
> > >> attached. If the circuit is equiped with photodiodes it can turn
> itself
> > so
> > >> that these will keep pointing at a light source: the circuit will
> > control
> > >> the motor in such a way that the side of the box with the photodiodes
> > will
> > >> keep pointing to the light-source (is it clear what I have in mind?)
> > >>
> > >> - it is not interesting from the practical point of view (at least I
> > >> wouldn't know an application which can't be done easier), but from
> the
> > >> physics and system-control point of view it is.
> > >> - it can be made with a bicore (which is a really cool circuit, for
> > >> refference see http://www.beam-online.com/Bicore_article/select.htm).
> > >> - the mass as drawn in the picture doesn't need to be excentric, as
> > long
> > >> as
> > >> it is quite a mass compared to the overall mass.
> > >> - the box should be able to rotate freely around the point to which
> the
> > >> wire is attached, else the wire will excert a force on the box wich
> > will
> > >> try to turn it; that only complicates things.
> > >> - a little friction however can be usefull because than the motion is
> > >> damped.
> > >>
> > >> What do you think?
> > >>
> > >> Wouter Brok
> > >>
> > >> PS: hope the file isn't too large
> > >>
> > >> << File: Idea1.GIF >>
>
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