[chbot] Hexapod - autonomously writing messages

Chris Hellyar chris at trash.co.nz
Sun Dec 28 21:32:14 GMT 2008

Not so much the speed, but the jerky movements....

Hexapods are very simple to get walking from a sequence point of view,
but getting them really smooth is much harder, as with any legged robot.

What he's done there is a very simple tripod gait.  Three legs down,
three legs up, and jerk.  Which is what I did with both of mine,
although I did start working on a 'ripple' gait table on the second one
but ran out or processing power with the small PIC I was using..  Was
probably my algorithm, if I did it now I'm fairly certain I would do it
differently, as is always the way with 20/20 hind site.

Wave/ripple gait is much cooler looking, and can give you continuous
looking motion:


And, also in the smooth movement department:

And: http://www.youtube.com/watch?v=n4JJEazpb_g which is quite cool as
well, obviously using propper geometry calcs!

With a PIC32 on board you should be able to create some adaptive gait
tables/routines in C to give very smooth movement.  Ripple/wave gait
also gives more strength as more legs are acting in 'drive' at the same
time (5 vs three), which would suit his project.

I would like to play with my hexapod, but I pillaged it for bits about a
year ago.  :-)

I don't actually have any working robot-like devices at the moment, must
work on that...  I've only just got over changing full time jobs earlier
in the year, and got back into doing some of my own stuff.  Robots are
bottom of the list unfortunately, under a pile of domestic stuff, and
the continuing saga of the PLC  that I've been wanting to do since I
sold the electronics business back in 2004!  (llloooonnnggg
project :-) )

Hope everyone had a great Xmas, and all the best for the New Year..

Cheers, Chris H.

On Wed, 2008-12-24 at 08:46 -0700, Michael Pearce wrote:

> I also thought he could have it moving a little faster..... but still
> pretty cool - guess you could modify yours and add a lawn cutting
> blade and draw in the grass (Thats what the whole project is about)
> Mike
> > It's nice, but nothing that clever IMHO...
> >
> > And, you'd think with 3dof legs and that much processing power you'd code a
> > dynamic gait to remove the jerking motion out of it.
> >
> > my 2c. :-)
> >

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