Alt-BEAM Archive
Message #06763
To: alt-beam@egroups.com
From: "Patrick Yeon" patyeon@hotmail.com
Date: Sat, 16 Oct 1999 06:38:47 PDT
Subject: [alt-beam] Re: Radio Communications?
I think it would be a great idea, but it would probably have to be big bots
so you can fit the circuitry in or they would need to have a computer hooked
up and listening with a program to tell em what to do.
I'm willing to try anyways.
PAT
>From: "Chris" <123abc@chek.com>
>Reply-To: alt-beam@egroups.com
>To: beam@sgiblab.sgi.com
>Subject: [alt-beam] Radio Communications?
>Date: Fri, 15 Oct 1999 22:16:53 -0400
>
> Ok, I know this is a lttle far-fetched but, I'm going to say this
>anyway. Wouldn't it be great if we could some how make some kind of radio
>transmitter and reciever on 2 robots (each has both), and one robot would
>come across some obsticle or something (hit a wall, anything you can think
>of), and then it would transmit a certain tone in acordance with what ever
>is needed, then the other robot would recieve this, play it on a tiny
>speaker (or something, it should work like a telephone beep), identify the
>tone and respond accordingly.
>
> I know that sounded hard (and probably impossible), but it would be a
>great research and engineering project. e-mail me if you think this would
>be a great project.
>
>Win a LAPTOP Computer and get your FREE E-mail Account at
>http://mail.chek.com
>
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______________________________________________________
6764 Sat, 16 Oct 1999 11:22:03 -0400 Re: What do I Need? - J Wilson's Gearmotors Mike Kulesza James Wilson
> I always for every problem I come across start with the basics. T try to
> break it down into small manageable bits, some times the problem can
appear
> so large it will overwhelm you.
> To start list the main goal of the project:
>
> To build a cool looking living robot style :Walker
>
> Next what are the main components of the walker, this is where the proj
can
> seem to grow without bounds as all sorts of ideas come flooding in for now
> lets just divide it into the four components that make a BEAM robot
> 1: Biological
> 2: Electronic
> 3: Aesthetic
> 4: Mechanical
> Well #2 has already been dealt with by Tilden so we can put a check mark
> beside that one, #3 lets put that on hold so that leaves #1&4. Numbers 1
> and 4 are linked and as we come to some discussions about one of them by
> default some choices are made about the other.
>
> So it would appear that you have some Idea of how you would like to
motivate
> your bot, and I am assuming that you are looking to the classic 'Miller'
> type arrangement. So that means that the bot will have a four phase
walking
> gate- left front, right rear, right front, left rear, repeat. To make
this
> work we first need some useful information about the motor being used. To
> read the label or ad and say a motor has 5oz.*in of torque really doesn't
> help much as we are not going to solve our problem mathematically (If you
> want to know how let me know and I will walk you through it). Take one of
> the motors and the leg arrangement you would like to use and put it
together
> (try to use a terminal block so you can change your mind). Now set up
your
> microcore and driver now using some sticky tape attach the other motor to
> the tip of the leg you have chosen. Fire up the microcore and adjust the
> pulse length long enough to lift the weighted leg through at least 45ø of
> arc both from below parallel to the ground and from parallel to the ground
> up.
>
> What does this tell you, well the implied question is Does the motor I
have
> selected have a POWER output large enough to complete the amount of WORK I
h
> ave asked of it? The two important terms are POWER and WORK. Power is
> measured in joules/second or what we are most familiar with is Watts, 1 W
=
> 1 J/s. Work is measured in say oz/in similar to our torque (or moment)
unit
> of oz*in. To get from work to energy and thus power one must integrate,
but
> we are empirical scientists and will not. For us we must just observe and
> tweak what to tweak 1. the length of the leg from the point at which power
> is being applied or the moment arm, 2 the amount of time the force is
being
> applied (this is called impulse) change the pulse length.
>
> Once a suitable pulse and leg length have been determined avery large
> portion of the mechanics have been tweaked to perfection or at least
> satisfaction.
>
> This process will tell you the maximum distance (plus or minus the square
> root of your shoesize) you can have from one leg tip or sometimes called a
> foot to the opposing motor to actually have it lift off the ground. Yes
> this is somewhat simplified but is a good start.
>
> You have also asked about center of mass, simply put the center of mass of
> an object is the point at which if placed on a pin the object would
balance.
> What does this gain you? Well to cause a rotation about that point uses
the
> least amount of energy as you do not have to overcome the eccentricity of
> any unbalanced mass. So what you say how does that help me build a better
> toaster? It doesn't but to improve the performance of your bot try to
have
> the center of gravity of one component pass through the center of rotation
> of the other thus minimizing the work required to move it. Okay so how do
I
> find these points on my bot? Well the center of rotation is easy the
output
> shaft of one motor right? Not exactly cause remember now the bot has four
> feet each moving in turn, shifting the center of rotation with each step.
I
> did say that this would get complicated. Tweak tweak tweak BEAM should
> really be called BEAMP P for patience. Think of each iteration as a link
on
> the chain of evolution striving for the perfect bot mechanics to allow the
> brain which has "finished" evolving at this stage to operate most
> efficiently.
>
> If I have succeeded in confusing the issue I apologize, but remain open to
> more questions.
>
> James :-))
> ----- Original Message -----
> From: Mike Kulesza
> To:
> Sent: Friday, October 15, 1999 6:02 PM
> Subject: Re: What do I Need? - J Wilson's Gearmotors
>
>
> >
> > OK, it seems as if i am having mechanical problems, even my new walker
> with
> > much higher torque gearmotors has the same problem. It will probably
have
> to
> > play around with some physics, centre of gravity, weight distribution
> etc...
> > However, is till dont really understand how all of these factors should
be
> > delt with... some tips would be nice!
> >
> > >From: "James Wilson"
> > >To: "Mike Kulesza"
> > >Subject: Re: What do I Need? - J Wilson's Gearmotors
> > >Date: Thu, 14 Oct 1999 21:27:50 -0400
> > >
> > >Wow!!!
> > >
> > >I just spent the last hour playing with my walker and found that I
could
> > >drive it with two 245's if I put the enable (pin 19) directly to
ground.
> I
> > >have the mechanics a little cock-eyed so it goes in circles but it
goes.
> > >
> > >I think that you have definetly provided ample current to drive them
try
> a
> > >little mechanical tweaking and you should get good results!
> > >
> > >My legs are approx. 7" total width, front and back. When the bot lifts
> it
> > >self up on its back legs the front leg drops with a mighty thud. I
think
> > >I'll have to name it Stomper.
> > >
> > >James:-))
> > >----- Original Message -----
> > >From: Mike Kulesza
> > >To:
> > >Sent: Wednesday, October 13, 1999 4:37 PM
> > >Subject: Re: What do I Need? - J Wilson's Gearmotors
> > >
> > >
> > > >
> > > > h-bridge, then 2 stacked ALS254's
> > > >
> > > > >From: "James Wilson"
> > > > >To:
> > > > >Subject: Re: What do I Need? - J Wilson's Gearmotors
> > > > >Date: Tue, 12 Oct 1999 21:31:50 -0400
> > > > >
> > > > >Just out of curiosity, what did you use to drive the motors?
> > > > >
> > > > >
> > > >
> > > > ______________________________________________________
> > > > Get Your Private, Free Email at http://www.hotmail.com
> > > >
> > >
> >
> > ______________________________________________________
> >
6765 Sat, 16 Oct 1999 08:30:44 PDT [alt-beam] 74HC240 question alt-beam@egroups.com "Patrick Yeon" Looking through the Radioshack catalog I notice the 74HCT240 chip, would it
replace the 74HC240 often needed? What's the "T" for?
does someone know where to get cheap 74HC240 or whichever chips?
Thx, PAT
______________________________________________________
6766 Friday, October 15, 1999 9:56 PM Radio Communications? beam@sgiblab.sgi.com Chris <123abc@chek.com>
> Ok, I know this is a lttle far-fetched but, I'm going to say this
anyway. Wouldn't it be great if we could some how make some kind of radio
transmitter and reciever on 2 robots (each has both), and one robot would
come across some obsticle or something (hit a wall, anything you can think
of), and then it would transmit a certain tone in acordance with what ever
is needed, then the other robot would recieve this, play it on a tiny
speaker (or something, it should work like a telephone beep), identify the
tone and respond accordingly.
>
> I know that sounded hard (and probably impossible), but it would be a
great research and engineering project. e-mail me if you think this would
be a great project.
>
>Win a LAPTOP Computer and get your FREE E-mail Account at
http://mail.chek.com
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