I Want Too....

That's actually not too hard, depending on what you want it to
autonomously do.  If you want it to just walk around and avoid bumping
into things, that's pretty easy.  If you want it to serve drinks at your
next party, that's harder.  :)


I wouldn't suggest trying to use those computers, except for programming
the microcontroller that you'll actually use as the brains on the bot.  
I'd suggest starting with a hexapod kit -- Lynxmotion has some nice
ones, and the ones based on their "Servo Erector Set" are especially
cool in my eyes because if you get tired of your hexapod, you can take
it apart and build something completely different.

  <http://www.lynxmotion.com/Category.aspx?CategoryID=3>

Start by building it and speaking directly to a servo controller (the
SSC-32 is a good one) from your PC.  Then choose a microcontroller
(there are gazillions to choose from), program it in your favorite
language, and stick it on the robot.

For sensors, you'll probably want at least a few of the Sharp IR
distance sensors.  These are available in various places, such as the
Mark III Robot Store: <http://www.junun.org/MarkIII/Store.jsp>

Good luck and have fun!
- Joe

As one of the gazillion microcontrollers suppliers out there, I'll
suggest you buy one of our ServoPod(TM)s or IsoPod(TM)s and save your
money on the servo controller, because our micro is so advanced it can
drive up to 26 servos from internal hardware, without taxing the
internal processor. Which means with our micro, you can set an RC
Servo, and forget it. The hardware will continue to generate the
position pulses with no intervention from the software.

You might look at the various videos on Lynxmotion site, to see our
software running hexapods, dancing sideways and diagonals, etc. Those
videos are kind of impressive. Anybody else ever seen a hexapod walk on
a diagonal?

--
Randy M. Dumse
www.newmicros.com
Caution: Objects in mirror are more confused than they appear.

Yes, though only after half a bottle of Jack.

-- Gordon

ROTFLMAO :->

The Christmas spirits are at large I guess.

Anybody else ever seen a hexapod walk on

My (6 legged) robot can. I wasn't aware this was considered to be that
hard of a feat?

-Mike

http://www.lynxmotion.com/ViewPage.aspx?ContentCode=videos&CategoryID #hex3

the diagonal walk:

http://www.lynxmotion.com/images/video/eh3/tripangl.mpg
http://www.lynxmotion.com/images/video/eh3/tripang2.mpg

Difficult part is it takes full kinematics to do properly. Don't think
most people bother. So you can draw your feet on a straight line in any
direction? Do you have videos we could see?


--
Randy M. Dumse
www.newmicros.com
Caution: Objects in mirror are more confused than they appear.

Right now the software I'm using isn't perfectly precise. Good to maybe
+-5 degrees accuracy.

I have written some software that will give me +-.5mm accuracy in leg
movement (and thus a fraction of a degree accuracy), but I am still
testing it.

I still fail to see what is so terribly difficult. All you have to do
is implement the full reverse kinematics for the legs. Basic
trigonometry assuming a 3-DOF leg. Anybody that got through highschool
math should not have trouble with it.

I don't have any videos of it walking in a non straight direction,
sorry.

-Mike

What you say is true, and particularly for someone for instance from
the Physics department (refering to myself). However, if you check with
University level students, and ask them about the ease of kinematics,
you'll get quite a different story. Full kinematics is "a big deal" in
the industrial tech department. Or at least that has been my
impression. Besides Mike Keesling and myself, you're the first one I've
ever heard that has done it for a hex 3dof walker. Ask around, and see
if what you find is different.

--
Randy M. Dumse
www.newmicros.com
Caution: Objects in mirror are more confused than they appear.

Hmm - I figured out the kinematics for my robot before I knew what
kinematics meant. I think most anybody capable of building a 6 legged
robot should be able to do it. I think one thing that may prevent many
from implementing full kinematics is the processing power necessary to
compute the positions of all the motors in real time if you want smooth
motion. And just laziness, of course. There are all sorts of
approximations that can be used - but for perfectly smooth movement -
you need a decent amount of processing power, at least I did.

Anyways - I'm glad I'm among the elite few. If you're interested, I'll
post a video of him walking at a random angle when I get my new control
algorithm finished (should be about a month or two). Hopefully the new
algorithm should look pretty darn smooth. We shall see!

-Mike

Yes, take a pat on the back.

There's no doubt it takes a fair amount of processing power to work all
the trig. functions working through the kinematics. Particularly when
you're considering 18 servos, each with a different angle, and doing it
over 50 times a second.


Yes, I'd be interested to hear.

Randy

    Game developers, however, do it all the time.  Look around
for inverse kinematics code.  For legs with unique inverse kinematics
that don't operate near their singularities, it's not that bad.

                John Nagle
                Animats

STage 2 is to get it to learn about its environment and remember paths
between certain points, the hexapod looks good, would I be able to evolve it
to do the above?

I suppose I need to know if i can add extra sensors and some sort of memory
functions to it either programatically or via hardware.

Yes, that's all standard stuff.  You start with the basic kit, and then
add additional sensors and processing power as desired.

Best,
- Joe

On Mon, 18 Dec 2006 17:08:00 -0000


check out "Insectronics; Build Your Own Walking Robot" by Karl Williams.

    http://www.mhprofessional.com/product.php?isbn