Alt-BEAM Archive
Message #03183
To: "'Dennison'" dennlill@buffnet.net,
From: "van Zoelen, Bram SSI-TSEA-352" Bram.A.A.vanZoelen@is.shell.com
Date: Tue, 11 May 1999 09:57:27 +0200
Subject: [alt-beam] Re: a useless idea
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 '=EDnertial 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
>=20
> Hello Dennison,
>=20
> 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.
>=20
> regards
>=20
> Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> tel: (604)590-7493=20
> fax: (604)590-3411
>=20
> > -----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
> >=20
> > 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.
> >=20
> > When the head swings and reverses direction, you get a tangential
> > acceleration found by
> >=20
> > Acceleration-tangential =3D Radius * AngularAcceleration
> >=20
> > From that we can calculate a rough idea of the force, given the =
weight
> of
> > our head, and the radius of the counterweight.
> >=20
> > Force=3DMass(weight)*Acceleration(tangential)
> >=20
> > But what about the inertia?
> >=20
> > Force =3D Mass * Acceleration
> >=20
> > so then
> >=20
> > Force =3D Mass * Radius * Angular Acceleration
> >=20
> > But we need some more befor we can go on, Torque is Radius times =
the
> force
> > or
> >=20
> > Torque=3Dradisu*Force and we know what force is, so we get:
> >=20
> > Torque =3D Mass * Radius^2 * Angular Acceleration (mr^2 =
represents the
> > rotational inertia)
> >=20
> > 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.
> >=20
> > So the Momenet of Inertia for our HEAD or mobile, or etc.. is
> >=20
> > Inertia =3D Sumation( mass *radius^2)
> >=20
> > 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
> >=20
> > 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.
> >=20
> > Dennison
> >=20
> >=20
> >=20
> >=20
> >=20
> > >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 >>
>=20
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