Alt-BEAM Archive

Message #02894



To: "'Dave Hrynkiw'" dave@solarbotics.com,
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Mon, 3 May 1999 12:55:13 -0700
Subject: [alt-beam] Re: Caterpillar


Thanks Dave!

This kind of anecdotal description with details really fills an information
vacuum for the new (post 93?) Beamers. It gives a flavour of the excitement
of the early days of Beam/robotics development. I wish we had more
background stories like this to contrast with "dry" facts that are the
likely result of compiling information in a history/genome index.

regards


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

> -----Original Message-----
> From: Dave Hrynkiw [SMTP:dave@solarbotics.com]
> Sent: Monday, May 03, 1999 12:32 AM
> To: Chiu-Yuan Fang; Andrew Miller
> Cc: BEAM List
> Subject: Re: Caterpillar
>
> At 03:09 PM 4/30/99 , Chiu-Yuan Fang wrote:
> >Dave was telling me about "PhotoPheeder". What kind of circuit did you
> use to
> >control it? I'm trying out different circuits in my ATpV
> >http://www.geocities.com/SouthBeach/6897/atpv.html
> >and would love to see your solution.
>
> Here's a bit of historia from when I was just getting into BEAM. Miller
> put
> together a "bio" sheet for his better robots (hmmm, pre-genome!). The copy
>
> he gave me has these details for the "PhotoPheeder II". Feel free (pending
>
> Miller's approval) to copy this into any GENOME project. Best I can tell,
> this device was constructed in early 1992, based originally on Mark
> Tilden's HBS BEAMants:
>
> Solarcells - 2 multicell packets, calc. cells; 5V nominal each
>
> Caps - Twin 94000uF 5V drive supplies; one 4700uF 5V "reverse panic"
> supply
>
> Battery - Two 3V lithium cells (currently dead, source for "reverse panic"
> (Dave's note: the original photovore contest as per the BEAM rules allows
> these lithiums)
>
> Engine type - Twin HBS drive engines with 3.3k bias; nominal trigger 3.1V
> - Single HBS reverse engine Nominal 2.7V trigger
>
> Drive - Gear reduction; 3V cassette motoer; Tani type final drive from
> modified printer paper feeders
>
> Chassis - Paper feeders bridged by glued perf board; brass tubing and
> stainless steel wire; Removable solar array and cct board.
>
> Behavior:
>
> The is the most complex of my machines. It starts with the most simple of
> behaviors. Basic Phototropic behavior, with mechanical tactile sensors for
>
> obstacle avoidance. A more difficult behaviors was introduced to allow the
>
> machine to "aback up" should it enter a zone of darkness such as a cave.
> This is accomplished by using a photo resistor to trigger the "reverse
> panic" system powered by the lithium batter "body fat". In an attempt to
> avoid potential problems with other competitors who follow the classic
> phototropic behavior, this machine was created as a "semi light pool
> avoider". That is to say that it begins its behavior with phototropic
> intent, but when the light intensity becomes greater than a preset level
> the machine will become "semi-photophobic". This behavior could be
> considered self preservation, as the robot now avoids conflict with other
> competitors who are holding Tilden's third law of robotics as the highest
> priority. This light pool avoidance technique works best in low light
> conditions such as 100W bulbs, but can be carried to situations with much
> brighter and more uniform lighting. The introduction of a moving light
> source, such as sun up/sun down, creates even more possible behaviors.
>
>
> Background: As this was my first attempt at creating a photovore, it
> proved
> to be quite a "voyage of discovery". Countless hours of frustration can be
>
> directly attributed to this machine. The basic chassis was created to
> challenge the line from the BRO guidebook which stated "... a photovore
> need not be a modified tank to compete." in fact this was the second
> chassis based on a modified printer feed mechanism. There are some obvious
>
> disadvantages to making such a "heavy duty" driveline, but the most
> obvious
> of which is partially compensated for by LOTS of solarcells. The machine
> has, however, proved its worth as an All Terrain Vehicle. At one point
> during the last competition, PHOTOPHEEDER actually climbed over another
> competitor and dragged it around for almost an hour. The light pool
> avoidance technique, although great in theory , aw immensely difficult to
> implement. The analog nature of most electronic components, and the
> resulting power losses caused endless problems. A functional circuit was
> finally created using a photocell and a photoresistor in series to give a
> current vs intensity rise that was much closer to a digital response.
> PHOTOPHEEDER II was the 1993 world champion. I hope to expand this
> machines
> "All terrain" style into larger robotic life forms in the future.
>
> Regards,
> Dave
> ---------------------------------------------------------------
> "Um, no - that's H,R,Y,N,K,I,W. No, not K,I,U,U, K,I,_W_. Yes,
> that's right. Yes, I know it looks like "HOCKYRINK." Yup, only
> 2 vowels. Pronounciation? _SMITH_".
> http://www.solarbotics.com

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