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Frnak McKenney posted on January 4, 2007, 8:47 pm
I'm working on a design for a something to impress and entertain my
niece Caroline, who has recently gotten involved with robots.
Caroline is eleven; my impression is that she hasn't done any
ground-up robot construction, but she does seem to have enjoyed a
Lego-based program at her school.
So... I have an old Radio Shack "Street Quake" R/C truck I've dug
out of my collection of thrift-store $2 specials, and I'm wondering
how I can come up with "something" that is:
- Interesting and/or amusing to an eleven-year-old,
- Autonomous, and
- Cheap. <grin!>
My first thought was a simple "wandering truck" that would
occasionally go to sleep, then wake up, and wander some more. Its
main goals would be to (a) move randomly so it looked like it was
exploring and (b) not run into too many walls.
Then I discovered Bert Van Dam's 'web site and read his article on
"Tom", a Subsumption-based robot that "chased" things, and things
started falling into place. Here's what I hope I'll be able to make
this truck do:
2) Find a dark place and hide ("sleep") for a while.
3) Chase moving objects (based on distance)
4) "Play" with humans (and possibly dogs and cats) by moving toward
them, following if they move away, and running away if they come
close.
("Tom" has a rather full array of sensors, but I'm hoping I can get
similar results with fewer, and a smaller investment.)
Well, after several days exploring odd places on the 'web, I haven't
been able to come up with a simple, clear, and inexpensive way to
tell if my robot is facing a warm-blooded creature. I've looked at
E-fields, radiometers, thermopiles, pyrometers, and all sorts of
noncontact temperature measuring devices with prices from $40 to
$500 (I even looked into a gadget called a capaciflector); the best
I've been able to come up with is sticking a pair of Fresnel-domed
PIR motion detectors on the front of the truck. (Panasonic/
Matsushita's 'MP' series have some really nice features, but they're
in the $30-$45 range).
I could do worse: somewhere in my collection is my father's Garden
Frog which croaks when it "detects people", apparently by rapid
changes in the intensity of light falling on it (think "CdS
photoresistor"), but even that involves detecting motion. I'm
curious as to whether anyone can suggest another approach.
Detecting the presence of humans (e.g. "occupancy") seems to still
be an Interesting Problem; I've seen USENET newsgroup discussions on
the topic as far back as 1997.
The PIR approach has some problems. First, because it detects
changes in temperature, it can't detect a nonmoving human. Second,
it's not much help in determining range, and third, even when motion
is present I'm not sure I can tell which direction the human is
moving. How about a $10 noncontact ranging IR thermometer?
"There's a 98.6 degF object 2.64 meters away" would be really nice,
since I could use the range measurement to "chase" or "avoid".
Since I'm still at the GedankenRobot stage (the point where many of
my best creations seem to get stuck) it's not hard to change my
design. Any suggestions will be welcomed.
* * *
A note on the R/C truck. I wan't thrilled with having to cobble up
an L293D/PWM arrangement, but it looks like I can re-use the trucks
existing -- and designed exactly for the motors and batteries --
drive electronics. This is one of many _many_ R/C and IR/C vehicles
built around the Realtek TX2/RX2 and TX2C/RX2C chipsets, and it
_looks_ like all I'll have to do is desolder the chip and solder in
a 16-pin header for a cable.
Tracing a PC board to build some idea of its circuit is a long,
tedious project (I've done it a few times, but it's never fun); it's
simpler to throw the whole assembly away and start again. Even
worse, you have to do it again for the next R/C vehicle. On the
other hand, patching into the circuit through _known_ points (the
RX2 pins) is not only straightforward but it's a _reusable_
technique. In fact, if I had the companion TX2 board, I could
control the truck from _it_ and connect it to the RX2 board with a
two-wire cable.
Will an AVR output pin properly drive the transistors controlling
the L/R steering motor and the drive motor? Guess I'll find out,
but even the _thought_ of accomplishing that kind of re-use warms my
auld Scots heart. <grin!>
* * *
If anyone's curious, here are a few pointers to some of the items
I've mentioned:
Bert Van Dam's 'web site
http://members.home.nl/b.vandam/
Connell 1987: Tom (Description of "chase" behavior)
http://members.home.nl/b.vandam/lonely/pagina37.html
Realtek RX2/TX2 and RX2C/TX2C datasheets
http://www.datasheetarchive.com/
http://www.mobicon.com/
PIR Sensors/Modules/Detectors (search on PIR, Fresnel, RE200B)
http://www.hvwtech.com/ SKU#35050 $10.95
http://www.allelectronics.com/ CAT#IRD-10 $3.95
http://www.electronics123.com/ BB054 $8.95
http://store.qkits.com/ QK76 $12.95
Discussion thread on finding Fresnel lenses
http://www.jesseshunting.com/forums/index.php?
s@9bf6d58c94f4f6fc69200d19b42dde&showtopicP48
Enjoy...
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)
--
Copper wire was invented when two Scotsmen found the same penny.
--
dan michaels posted on
Re: Robots that play with people and pets
Hi Frank. Just a couple of comments to boil down your post. van Dam has
a lot of interesting stuff on his site. You should be able to cook up
an interesting bot using subsumption techniques, possibly coupled with
an "overseer" device that can select between different behavioral
schemes for different situations.
Joe Jones' books "Mobile Robots" and also "Robot Programming" are very
good practical introductions to subsumption techniques. Added to this,
Joseph Jones & Ben Wirz discuss their RoCK robot, which had a number of
different behaviors coded using subsumption techniques, and which they
could select between using a manual pushbutton. One behavioral
repertoire coded in were little song'n'dance routines. Kids love this.
http://www.circuitcellar.com/magazine/142toc.htm
I haven't experimented much with PIR devices, but it seems you could
use them to produce an interesting robot which would either approach or
run away from humans, or animals, in different circumstances. Having
such "ambivalent" responses might have some appeal to teenagers. You
might also check Braitenberg's classic book "Vehicles" regards coding
different forms of robot behavior for different situations.
More to practicalities, R/C cars generally do not make the best robot
platforms, since they are made for speed, while most robots tend to
lumber around at much slower rates. In general, the sorts of small
computers used in small robots to do have enough processing power to
deal with high speeds. R/C cars generally will not run well at slower
speeds, since the gear trains are not geared properly for this. You
won't get enough torque at the low end.
Also, the L293D h-bridges only handle 600-mA max, and most R/C car
motors will draw much more than this. It's probably easiest to try and
tap into the h-bridges already present in the car.
Re: Robots that play with people and pets
Dan,
Thanks for taking the time to reply.
On 5 Jan 2007 11:19:00 -0800 and On 5 Jan 2007 11:14:39 -0800, dan michaels
van Dam's description of his "Tom" robot was what really started
pulling things together for me. The Subsumption approach seems to
have worked well for van Dam, and I may well adopt it or something
like it, but before I start coding I need to work out a clear and
reasonably specific statement of how Caroline's toy will behave when
she turns it on. I may change it later, but at least I won't be
Thanks for the reminder. I dug out my copy and I've flagged a
couple of points to re-read when things calm down around here.
Thank you for the pointer. My Journal Storage and Retrieval system
(see also: Stacks'o'Magasines <grin!>) turned up issues #141, 142,
and 144, but it appears that I pulled #143 out some time back (for a
ReallyGoodReason(tm), I'm certain) and never got around to replacing
it.
The "Waltz" behavior sounded interesting, but there's little
description beyond "plays songs and moves in a pattern". Still, it's
worth thinking about.
One of my goals is to have the robot respond to humans and pets, and
be able to distinguish them from (say) radiators and fireplaces
(especially the latter! <grin>). PIR detectors, as I mentioned in
my original post, are the best thing I've found, but I'm hoping
someone out there has a better approach. If not (and several past
Usenet exchanges on the topic were inconclusive), I'll use them and
hope that I can be "good enough" to amuse Caroline.
But... R/C cars, carefully acquired ("You're not throwing _that_
away, are you??!!") are much cheaper than the cost of most motors,
battery packs, and motor controllers.
Yup. And as I mentioned, knowing the details of the TX2/RX2 IC
family should let me do this without spending hours following PC
board traces and trying to get part numbers off components.
Wish me luck. I'm hoping that creating this for Someone Else will
be incentive enough to ensure that it at least makes it past the
GedankenRobot stage; I have way too many bits and pieces of "virtual
And if any one out there has any suggestions for a cheap and
reliable People Sensor, please feel free to comment.
Thanks again, Dan.
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)
--
"Provide me with ships or proper sails for the celestial atmosphere
and there will be men there, too, who do not fear the appalling
distance" -- Johannes Kepler
--
Curt Welch posted on
Re: Robots that play with people and pets
For what you are trying to do, I would strongly suggest that evolving your
code as you write it is the only way to go. Your goal is to make the robot
interesting, and there's just no way possible for you to precisely define
"interesting" before you start coding. You can't even do a good job of. No
one can really.
Doing this type of evolutionary design work is not bad practice - it's the
only way to solve problems that haven't already been solved by someone
else. If there were books written on how to design and build interesting
interactive robot toys, then sure, get the book and read it before you
start (as you are doing). But in the end, hopefully, you will add some
features to your robot that no one has added to any other robot (or never
wrote a book or paper about) - and you come across these ideas by
evolutionary exploring of the design space. Build, play, think, build play
think, continue as long as possible.
Sensory data processing is one of the areas that most robots are extremely
weak in. It's a very hard problem that no one has yet come up with a
simple general answer to. If the sensor doesn't tell you want you want to
know directly, most robots simply don't "know it". In general, it's a
complex problem of statistical analysis that simply doesn't get built into
most hobby robots. It's what keeps complex sensors like video cameras from
being used more on small robots.
I assume you are talking about some type of heat sensor (IR?). It seems to
me that might get confused with various heat sources as you suggest. But,
it might turn out that the confusion makes it all that more interesting as
the robot tries to play with the fireplace, or a heat vent. ("oh look, he
likes the fire!"). And this is where the evolutionary design approach
really works. Instead of worrying about how it might get "confused" just
write some code taking your best guess as to what might produce interesting
behavior and see what behaviors emerge. If one of the behaviors is to
drive itself into a hot fireplace, then evolve the code to make it stop
that. :) You could make it be attracted to a low heat source but run away
from a high heat source for example - which could cause it to move towards
and then away from the fire place until something more interesting grabs
its attention.
I suggest that subsumption/reaction based approaches are most likely to
produce the most life-like and in turn, the most interesting behaviors.
And when interesting and entertaining is what you are shooting for instead
something precise like "vacuum the entire floor without missing any spot",
then you don't have to worry about the complex interaction of the different
behaviors - the more they interact in unpredictable ways the more
interesting it is likely to be. Robots that are predictable quickly become
uninteresting.
--
Curt Welch http://CurtWelch.Com/
curt@kcwc.com http://NewsReader.Com/
Joe posted on
Re: Robots that play with people and pets
One thing you may want to consider is the low cost PIR sensors they
sell (in Wal mart) for under $15. I forget the brand name, but I had
disassembled a few of them a couple of years ago to build trailcameras,
in order to photograph wildlife as it passed by the camera box. I
found the plans, with schematics and details on jesseshuntingpage.com
I am not sure if the page is still there, but it's worth a try. I know
of no other way to detect a moving warm body then this. Unless you buy
the sensors (the wavelength that we give off is 10 microns, by the
way), alone, and then buy a lens (fresnel of some type ) to detect just
the 10 u radiation. I think they are called pyrosensors. Google is your
friend there.
Anyway, hope this helps.
Joe
Re: Robots that play with people and pets
Joe,
Thank you for responding.
--snip--
You can find a sensor (the RE200B), the lens, and complete modules
for even less (URL snipped from my original post):
+> PIR Sensors/Modules/Detectors (search on PIR, Fresnel, RE200B)
+> http://www.hvwtech.com/ SKU#35050 $10.95
+> http://www.allelectronics.com/ CAT#IRD-10 $3.95
+> http://www.electronics123.com/ BB054 $8.95
+> http://store.qkits.com/ QK76 $12.95
I _think_ I have some of the BB054-style bubble-modules... er, "in
a box somewhere", but if I can't find them that's what I'll probably
try first. I need to work with them a bit to get a sense of how
their output signal is affected my various stiluli so I can decide
whether or not if they're what I'm looking for (or more likely, "the
best I can do" <grin!>).
Looks like it's time to grab one of those nice Rubbermaid storage
boxes and make a "grand sweep" of all my various Parts Repositories
(scattered across three rooms and half a basement) to collect "stuff
that might be useful".
Was this the thread (another URL snipped from my original post)? Or
was there more stuff there that I missed?
+> Discussion thread on finding Fresnel lenses
+> http://www.jesseshunting.com/forums/index.php?
+> s@9bf6d58c94f4f6fc69200d19b42dde&showtopicP48
I did run into a lot of other sensors when I was looking for
non-contact temperature measurement devices, but the prices were a
bit steep for my purposes (e.g. the Panasonic / Matsushita units I
mentioned).
I do appreciate your contribution (and Dan's and Curt's). Given
Earthlink's recent News Server problems (down fo a full week last
month) it's also reassuring to know that my posts are getting out.
The "people sensor" question seems to recur periodically; Gordon
McComb contributed to a round of it back in 2000. It seemed likely
that if someone had found a really good approach I would have run
into at least a reference to it in my 'web searches; on the other
hand, it was a question worth asking.
Ah, well. Time to go do some RealWork(tm) so I can spend some time
on "fun" stuff like this robot-to-be.
Thanks again.
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)
--
You are not thinking. You are merely being logical.
-- Neils Bohr to Albert Einstein
--
Re: Robots that play with people and pets
You might also be interested in taking a look at what Rod Brooks did on
one of his first robots, Genghis.
http://www.ai.mit.edu/projects/genghis/genghis.html
Subsumption based, and all of those round things on its nose are PIR
sensors.
Re: Robots that play with people and pets
Dan,
Thanks for the pointer.
Very impressive animations, and fortunately small enough that
mplayer on a 450MHz P-II can handle them.
Really? They looked like ultrasonic transducers, but the PDF file
listed with the MOV animations doesn't say much at all about sensors
of any kind.
Anyway, it looks like somethign that would be fun to build... once
I get a DOD-funded research grant to pay for all those servos.
<grin!>
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)
--
The joy of research must be found in doing, for every other
harvest is uncertain. -- Theobald Smith
--
Re: Robots that play with people and pets
http://www.google.com/custom?&q=brooks+genghis+pyroelectric
try Hitec HS-322HD at $10/ea from several vendors.
Re: Robots that play with people and pets
--snip--
IOW, "Sorry it wasn't in the PDF file. I don't have the specifics
at hand, but you can probably find something via Google." <grin!>
The search turned out really well, especially the part about using
"pyroelectric" rather than "PIR". It even turned up the following,
which pointed out that (a) one could use a motion detector to detect
still, warm objects (or is that "still warm" objects? <grin>), and
(b) why EEs don't waste time playing with water balloons:
Hoser: A Squirting Mobile Robot
http://www.cs.cmu.edu/~chuck/hoserpg/hoser.shtml
http://www.cs.cmu.edu/~chuck/hoserpg/hospapr.html
"Two pyroelectric sensors were also mounted on the robot to
detect body heat. One was mounted, forward looking, at the end
of the arm. The other was mounted on top of a Futaba servo on
the toy's "head" to scan back and forth looking for people."
So the trick is to get a DOD contract to supply these exact units
to, say, the Army, for $817 each. "Kinky... I like it".
In the mean time, I'll see how hard it would be to pair a PIR with a
Sharp IR Ranging unit and use a servo I have left over from a prior
project to "sweep" the two back and forth inside the truck cab.
All I need is a "Cylon" sound to go with it. <grin!>
(And a redesigned bumper. And a couple more IR obstacle detectors.
And a voice-input command system. Oh! How about TV remote IR
driving capability... this is how I wind up with a basement full
of GedankenRobot parts. <grin?>)
Anyway, thanks again.
Frank
--
"A ship in harbor is safe, but that is not what ships are built for."
-- John A. Shedd
--
Re: Robots that play with people and pets
Curt,
Thanks for joining in.
Agreed. I can't precisely define it. On the other hand, I think I
need to have some kind of general idea of what I want to happen. I
may well (as you point out) wind up going back and tweaking my
specifications based on what I learn is possible.
Agreed. Fortunately, as van Dam's 'web site
http://members.home.nl/b.vandam/
and Joseph Jones' (and others') books demonstrate, I don't have to
choose between starting _completely_ from scratch and waiting for
SomeoneElse(tm) to come up with a solution. There is a great deal of
material to build on.
"Never give in. Never surrender!"
(Winston Churchill? Tim Allen? Someone along those lines <grin!>)
The use of sensors is an incredibly wide-ranging topic. One of the
"Holy Grails" of A.I. research has always been a Magic Box that
would take a bunch of sensor inputs and Somehow Deliver The Right
Answers: from Arbib and Papert to Neural Nets to The Kalman Filter
to Subsumption.
Fortunately, I don't have to creat a GUTER (Grand Unified Theory of
Everything Robotic) to build what I have in mind (That can probably
wait 'til _next_ week. <grin>)
But it can be very difficult to "think like your robot". Even if
you imagine yourself inside a sound-, vibration-, and light-proof
box with a panel full of LEDs, dials, and switches, you also have to
think at a "ground level" of perhaps 3" (where the world looks very
different) and accept that you may never "know" just how many scars
you've left on the wall or how many cats have gone scurrying out of
your way. In fact, you won't even realize that you're lying upside
down with your wheels spinning because you didn't detect the top of
a stairway...
I complain about my poor eyesight, but things could be a _lot_
worse. <grin!>
Could be. And, as you point out, I'll have to wire it up, program
it, and see what happens (and then pick out th parts I like and keep
them).
Hm. I don't think you intended that statement _quite_ as literally
as I "heard" it; there's Chaos near one end of a spectrum, and
Crystal-lattice Rigidity near the other. My experience has been
that most of the things I find interesting are located near
boundaries, or, in this case, something like "unpredictable
interactions between predictable components".
Yup.
Thanks for the comments.
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)
--
"A good traveller has no fixed plans and is not intent on
arriving." -- Lao Tzu (570-490 BC)
--
Re: Robots that play with people and pets
Yeah, I was even thinking that as I wrote it. Pure chaotic random movement
would not be very interesting either.
For sure. Finding the right balance between predictable and unpredictable
is where we seem to find things the most interesting. I believe I even
remember reading a comment by a composer saying the same thing about music.
--
Curt Welch http://CurtWelch.Com/
curt@kcwc.com http://NewsReader.Com/
Joe Strout posted on
Re: Robots that play with people and pets
It's a general principle of psychology. In a nutshell, learning is fun,
and most fun relates to learning in some way. Something that's
completely predictable is no fun because you have nothing more to learn
from it. Something that's completely random is no fun because there is
nothing you CAN learn from it (though it may be fun at first until you
realize this is the case). Fun things are those which you can
continuously learn from.
Best,
- Joe
Re: Robots that play with people and pets
Um... reminds me of Dave Gorfein's Behavioral Psychology classes.
Let me think a minute.
While it's true that my robots work occasionally, it's also true
that I learn much more when they don't work. Can I conclude,
therefore, that my robots are _learning_ to malfunction in order to
get more of my time and attention?
Aaaaauuugh! It's A Conspiracy! (but it does explain a _lot_!)
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)
--
"Bother!" said Pooh, as the warp core went critical.
--
Re: Robots that play with people and pets
Heh. One of the first sensors I want to put on my bots (when I get that
far -- which should be pretty soon!) is some sort of tilt sensor. A tip
switch (or several such) could do in a pinch. Nothing makes a robot
look all kinds of stupid more than spinning its wheels upside down.
The next thing I want on my bots is a way to tell when the wheels or
feet aren't touching the ground at all. With feet this is pretty easy
(just stick a force sensor or two to the sole). With a wheeled bot it's
harder, unless you also have a suspension like the Roombas. But I feel
it's important, because a bot continuing to spin its wheels when you
pick it up looks only slightly less stupid than the one doing it
upside-down.
Of course our robots are going to actually BE stupid... but they
shouldn't APPEAR that way to a casual observer. (A lesson I learned
from computer-game AI programming!)
Best,
- Joe
Re: Robots that play with people and pets
I don't think that would ever bother one of my designs; none of them
Seriously, you might check out the Sharp GP1S36 Tilt Sensor; it's a
$2 unit with a metal ball and two optical interruptors.
If you were monitoring motion with (say) a hacked optical mouse
mounted in the underside of your robot it might be possible to
detect being picked up. Or, if you have a ring of "cliff
detectors", you can make a special case to handle all of them going
off at the same time.
Yes, but the nice thing is that it takes so _little_ to convince a
human being that you're behaving intelligently. <grin!>
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)
--
Writers listen for harmonies; civilians listen for melody alone.
For them the facades of ordinary situations are opaque, and they
see what is there to be seen. Writers are attracted to translucence.
We start with nothing but an idea, an agitation, a compulsion, an
irritation. That, plus a bumblebee's faith that it can fly.
-- Hal Ackerman / Write Screenplays That Sell
--
Rich Grise posted on
Re: Robots that play with people and pets
If she's eleven, and not retarded, a toy car that chases her around the
room will get really really boring Real Soon. :-)
What you do, is let her program whatever she wants into it; and get her
today's equivalent of an Erector Set, and let her make her own accessories
and stuff.
Good Luck!
RIch
Re: Robots that play with people and pets
Try this site for PIR sensor info:
http://www.web-ee.com/Schematics/PIR/pir.htm
Joe
Re: Robots that play with people and pets
--snip--
Thanks for the pointer. The PDF file has a schematic, plus a
description of how the PIR sensor and lens work.
In other good news, my missing three PIR modules turned up in a box
in my basement (turns out that they're KitsRUs #76 units). Next
step is to pull out my 'scope. hook one up, and see how it reacts
to hand-waving in various directions.
And then... Major Surgery on the truck!
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)
--
One of the demanding things about social life is that it fights
back. While you figure out how to move from tree to tree, the
tree just sits there, and while you figure out how to crack a
nut, the nut waits patiently. But while you are figuring out
how to deal with another monkey, it is figuring out how to
deal with you, or a third monkey steps in to make the deal.
-- Susan McCarthy / Becoming a Tiger
--
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