Alt-BEAM Archive

Message #04343



To: "'beam@sgiblab.sgi.com'" beam@sgiblab.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Mon, 7 Jun 1999 19:22:57 -0700
Subject: [alt-beam] Re: Solar Walker



content-type: text/plain;

Hello James,

As a follow up on my earlier comments, here is the LIGHT WALKER 1.0 design
as shown in the attached schematic. In this design the SE function has been
put inside the microcore loop. From another perspective this is a pentacore
design. The 1381 acts like a combination Nu, PNC and SE trigger. Note that
the 74HC14 and AC240 are powered up all the time. Normally the 4Nv outputs
will all be high, the motors will be stopped and no current will flow. The
solar panel will charge up the main cap and also the memory cap of the 1381.
The memory cap ensures that the 1381 input voltage will not drop during the
first process interval when the motor current starts to pull down the main
capacitor voltage. When the 1381 fires it "injects" a process into the first
Nv with a rising edge. This process ripples through the other Nvs and when
the process reaches the last Nv it resets the memory cap of the 1381. This
sequence is a 4Nv process cycle which causes the bot to advance by one step
on each leg. Next the solar panel charges the main capacitor and the 1381
memory cap back up and when fully charged the 1381 triggers the next process
cycle. If there is enough charge on the main cap the SE fires almost
immediately and the walker continues uninterrupted. This embedded SE design
can be extended to 6Nv or 8Nv designs as well.

The reverser circuit is quite a nice solution to the problem of early
reverser time out when the LIGHT WALKER only walks intermittently. To avoid
this problem, the reverser memory capacitor is discharged in steps, one
process cycle at time, with about 7 or 8 cycles required to return to
forward motion regardless of the time between steps. In addition the
reverser circuit switching is synchronized with the start of each cycle to
avoid the typical gait recovery time associated with asynchronous reverser
circuit switching. This synchronous reverser idea can be applied to many
walker designs and imho is a nice contribution to the state of the art of
BEAM tech.

The LIGHT WALKER still needs tactile inputs. Perhaps it can be left as an
exercise for the reader to complete the full LIGHT WALKER design.

enjoy

Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
tel: (604)590-7493
fax: (604)590-3411


<>


> -----Original Message-----
> From: James Taylor [SMTP:edgar_the_hate_bug1@yahoo.com]
> Sent: Monday, June 07, 1999 2:35 PM
> To: beam@sgiblab.sgi.com
> Subject: RE: Solar Walker
>
> I don't understand this?
> The PNC thing I sorta understand
> I like the unclosed microcore though, but how would it
> fall into the right state without a PNC, or a few
> processes to start?
> Disable the 245 sounds like a good idea too,
> expept, would the Microcore run all the time. How
> could you coordinate the right walking pulses, with
> the timed charges
> The time delay PNC sounds the best, having maby a
> 10-20 second delay between each pulse, allowing time
> for recharge. Any ideas?
> Any at all?
>
>
> --- Wilf Rigter wrote:
> > No need for a PNC, no need to disable the 245, and
> > perhaps use
> > the output of the last microcore stage to reset the
> > SE on the
> > lagging edge.
> >
> > enjoy
> >
> > Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
> > tel: (604)590-7493
> > fax: (604)590-3411
> >
> > > -----Original Message-----
> > > From: Benjamin Edward Hitchcock
> > [SMTP:beh01@uow.edu.au]
> > > Sent: Sunday, June 06, 1999 4:48 PM
> > > To: beam@corp.sgi.com
> > > Subject: Re: Solar Walker
> > >
> > > There are two things I would try if I were you:
> > >
> > > 1.
> > > Use the SE to initiate a 'pulse' around the
> > microcore. This means tthat
> > > your microcore isn't a closed loop, it is just an
> > open one - the last
> > > connection isn't made.
> > > So when the SE fires, it starts the pulse going,
> > the walker takes one
> > > complete cycle (step) and then waits for more
> > charge.
> > >
> > > I imagine this would make the walker a bit
> > lopsided, because one side of
> > > its operation would have more charge (voltage)
> > available to it. (ie the
> > > first state of the microcore always has more
> > voltage than the last state).
> > > Worth trying, though.
> > >
> > > 2.
> > > Use the SE to enable a 74XX245 driver chip.
> > Instead of tying the enable
> > > pin low, use a SE to pulse it low when there is
> > enough voltage to run the
> > > motors.
> > > This won't reasult in lopsided operation, but some
> > steps might be a bit
> > > jerky, and I would guess that sometimes the one
> > leg would rotate twice in
> > > the one direction. I think you would need end
> > stops for this
> > > configuration, or springs or something along
> > those lines.
> > >
> > >
> > > Good Luck!
> > >
> > > Ben
> > >
> > > ----- Forwarded message from James Taylor -----
> > >
> > > Hello,
> > > Need some help solarizing a walker. I read
> > the
> > > BEAM tech FAQ, and came up with the time delay
> > PNC.
> > > Only question is, do you need one of them for ever
> > Nu?
> > > If not where is it wired into the Micro Core?
> > > I would aslo like to know if their is a better
> > way
> > > to solarize a walker, not sure, but I heard once
> > that
> > > someone wired the microcore to have constant
> > power,
> > > and the leg motors to fire off after the charge?
> > > Anything that works is fine for me.
> > >
> > >
> > > ===
> > > Everything I say can mean one of two things...If
> > something I say makes you
> > > mad....I meant it the other way.
> > >
> > > James Taylor
> > > URL: http://fly.to/springmeadows
> > >
> >
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> > >
> > >
> > >
> > >
> > > ----- End of forwarded message from James Taylor
> > -----
> > >
> > > --
> > > Nothing is foolproof to a sufficiently talented
> > fool.
> >
>
> ===
> Everything I say can mean one of two things...If something I say makes you
> mad....I meant it the other way.
>
> James Taylor
> URL: http://fly.to/springmeadows
> _________________________________________________________
> Do You Yahoo!?
>
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