Alt-BEAM Archive
Message #13518
To: beam@sgiblab.sgi.com
From: Ben Hitchcock beh01@uow.edu.au
Date: Mon, 17 Apr 2000 10:15:11 +1000 (EST)
Subject: Re: A reply to Zoz ... and a challenge for advanced/bored BEAMers.
> Hi, all.
>
> The following discussion is relevant to the challenge ... but if you
> find the talk boring, skip to the end of this note, where I've spelled
> out the challenge.
[BIG Snip!]
> --------------------------- The Challenge ---------------------------
>
> Here is a challenge for BEAMers that are getting bored with solar
> engines and microcores. Try building a robot that tries to avoid getting
> stepped on. Zoz's diagram is an excellent model ... do it in
> BEAM/digital as he suggests, or try it with 99% BEAM as I advocate.
>
> The avoidance part is easy: Move out of the way, hide, or attract
> attention (flash a light, make a noise, wave a flag, dance a jig). These
> have all been done by various people.
>
> The sensors are the tricky bit. You probably need to use several sensors
> to be "sure" that a human/animal/predator is approaching. Sound,
> proximity, vibration, heat detection ... these all come to mind.
Female chickens will stoop down whenever a shadow falls over them, because
they think that a rooster is about to mate with them. A shadow cast by a
human works just as well as a rooster. I wonder just how 'sure' a robot
needs to be? If it has a full capacitor or battery, then what harm can it
do by activating its alarm even if it's only a bit 'sure'? My point is
that I don't think you need THAT many sensors to figure it out. Someone
will jump if you tap them on the shoulder, whether they hear you or not.
>
> To add to the challenge, avoidance activities should be appropriate to
> the conditions. Dancing a jig in the dark isn't likely to attract
> attention :)
>
> You can also extend the idea to anti-predator activities. Squirm or make
> a loud noise when picked up (OK, no scalpels or lethal voltages please
My Vibra-popper already does this... sort of. I figure that it's going to
get
stepped on no matter what it does, so at least be crunch-resistant. It is
as flat and wide as possible, and I'm going to encase the whole lot in
silicone rubber to enable it to flex a bit. When
a sensor has a shadow fall on it (from a human foot, or if the light turns
off) then it vibrates like crazy. After sitting in the sun and doing a
convincing replica of an epileptic seizure every few seconds, putting it
in a pocket will cause it to vibrate like crazy for a good 10 seconds.
It sure is different to the normal poppers that just don't fire if a
shadow falls on them. This one certainly lets you know if a shadow falls
on it whether from a foot or something else. Granted, all it is is a
glorified popper with a 1F capacitor, but as a first start at human
avoidance it's not too bad.
I've left it on my desk and invited a visitor to pick it up. Sitting on
my desk, it won't vibrate often at all, so when she picked it up and it
started vibrating like crazy she was so frightened that she dropped it!
*Quite amusing!*
> I'd love to hear about your successes (and failures as well), and I'll
> be happy to help if you decide to go the all-BEAM route.
Well.. I haven't had time to try the bristles idea to actually get it to
go where it is supposed to, but that will come. Uni holidays next week!
Ben
13519 Sun, 16 Apr 2000 17:24:01 -0700 RE: reverser "'beam@sgiblab.sgi.com'" Wilf Rigter Yes and No.
No, the REVERSER will definitely not work with the simple 4 (bipolar)
transistor type h-bridge.
Yes, it works fine with a 4 mosfet h-bridge and it will probably work with
Mark's 6 transistor h-bridge for most applications but ......
the maximum current the h-bridge can deliver to a motor is sensitive to the
value of the input resistor. Mark's design calls for 50K and up resistors.
With a 5V supply and 50K resistors, the max current is about 100ma before
the transistors come out of saturation and you start losing power. With the
100K input resistor shown in the h-bridge schematic the max current is about
50ma. So, depending on the motor load, the extra 47K in the REVERSER in
series with the h-bridge input resistor can reduce max saturated current to
30ma. Depending on the logic and the motor (especially with hobby servos),
if the resistor is inserted during backup when the efficiency of the walker
is poor (not optimized), it could make a noticeable difference.
There is a simple solution for use with the 6 transistor h-bridge: use a
10K resistor in the REVERSER to minimize the effect or add a buffer in
series with the REVERSER output to restore full drive capability, compatible
with all kinds of h-bridges.
regards
wilf
> -----Original Message-----
> From: Ian [SMTP:Ian@beam-online.com]
> Sent: Sunday, April 16, 2000 4:26 PM
> To: beam@sgiblab.sgi.com
> Subject: Re: reverser
>
> Hi Wilf
>
> > The Beam Online reverser circuit cannot directly drive an h-bridge
> input,
> > let alone a motor. Just use it to drive HC/AC inputs (ie HC/AC245 or
> > HC/AC240 motor drivers) and all will be well.
> ? I've used it with the h-bridge many times with no problems. ?
>
> Laterz
> \^^^^^^^^/
> (.)(.)
> -------------------------.oooO-- (__) --Oooo.--------------------------
>
> There is only one true "SyNeT"
> BEAM Online - http://www.beam-online.com
13520 Sun, 16 Apr 2000 17:53:48 -0700 RE: A reply to Zoz ... and a challenge for advanced/bored BEAMers . "'beam@sgiblab.sgi.com'" Wilf Rigter Hi Ben,
Your vibra popper crack-a-joke chicken buzzer sounds great but how about a
solar powered whoopi bot defending itself to STOP PEOPLE FROM SITTING IN MY
FAVORITE CHAIR!
grin
wilf
> -----Original Message-----
> From: Ben Hitchcock [SMTP:beh01@uow.edu.au]
> Sent: Sunday, April 16, 2000 5:15 PM
> To: beam@sgiblab.sgi.com
> Subject: Re: A reply to Zoz ... and a challenge for advanced/bored
> BEAMers.
>
---8<---
> Female chickens will stoop down whenever a shadow falls over them, because
> they think that a rooster is about to mate with them.
---8<---
> My Vibra-popper already does this... sort of.
---8<---
> when she picked it up and it
> started vibrating like crazy she was so frightened that she dropped it!
>
> *Quite amusing!*
>
> Well.. I haven't had time to try the bristles idea to actually get it to
> go where it is supposed to, but that will come.
>
> Ben
13521 Sun, 16 Apr 2000 19:54:03 -0500 Quadrapod Update... KINDA up! BEAM Richard Piotter Well I'm including a list of file names for the images. I had some power
problems here. Lost power about 20 times last night and this morning.
Realy hampered my work on the update, but I DID get the information uploaded.
The Misc section has been updated. Look under school projects.
Monitor link isn't complete though. For the Quadrapod, Battery Charger
system, and the monitor images, you can go to the address below, and
look for the following filenames of the new files.
I'll have HTML up later.
http://richfiles.calc.org/robots
Charger Related Pictures
BatterysKeys.jpg
ChargerModification.jpg
ChargerSchem.gif
ChargerTransformers.jpg
Monitor Related Pictures
BassReflex.jpg
BassReflexDetail.jpg
LCDPCB.jpg
PortableMonitor.jpg
PortableMonitorCamera.jpg
PortableMonitorInside.jpg
VideoTransmitter.jpg
Quadrapod Related Pictures
QuadrapodBattKeyIn.jpg
QuadrapodBattKeyOut.jpg
QuadrapodLegBack.jpg
QuadrapodLegBottom.jpg
QuadrapodLegFront.jpg
QuadrapodLegSide.jpg
Quadrapod Blueprint Related Pictures
QuadrapodPanelsBlueprint.gif
QuadrapodFrameBlueprint.gif
QuadrapodLegBlueprint.gif
Walkman Jr. Related Pictures
WalkmanJr3766.jpg
--
Richard Piotter The Richfiles Robotics & TI web page:
richfile@rconnect.com http://richfiles.calc.org
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13522 Sun, 16 Apr 2000 18:19:30 +1000 Re: A reply to Zoz ... and a challenge for advanced/bored BEAMers. "David Perry" you can buy them (the PIR detectors) at www.oatleyelectronics.com - just the
circuit board though - might be worth looking into.
> Now I need to hack a motion detector and figure out the rest of the
> circuitry :)
>
> Bruce
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