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[DPRG] Re: Interesting robot to check out...

Subject: [DPRG] Re: Interesting robot to check out...
From: Kenneth Maxon kmaxon at qwest.net
Date: Mon May 28 15:00:01 CDT 2007


Yes, ProtoBot is a skid steer platform.  It has only one set of drive motors
per side with a chain to engage both front and back wheels.  The motor
driver CCAs are common design to the six wheeled robot I am building.  Since
the six wheeled robot has 10x drivers I decided it was better to build two
prototypes throw them on ProtoBot and get it all debugged before investing
the significant time / effort it will take to lay out 10 of them on a common
board, go through all the work to lower the interference / radiation only to
find that I've made a bone head mistake.  Yep those happen every once in a
while and now that I am no longer compensated for overtime work, I have to
watch the pennies and bone head mistakes on that scale.

When it comes to the Sojourner robot, I am still debating breaking up the
motor drivers into individual boards and distributing them out into the
wheels next to the motors.  At that point using differential twisted
shielded pair to move PWM from a differential driver out to the wheels
rather than amplified / switched high current DC relieves a good number of
problems.  Additionally with the motor drivers right down on the motors
inside the wheel, leads to a fully contained model from an EMI stand point.
This should go a long long way towards reducing the exposure to the IMU from
unwanted radiated fields.


-----Original Message-----
From: dpa [mailto:dpa at io.isem.smu.edu]
Sent: Monday, May 28, 2007 2:51 PM
To: Kenneth Maxon
Cc: dprglist at dprg.org
Subject: Re: [DPRG] Re: Interesting robot to check out...


You continue to amaze me.  The quality and _quantity_ of work you
turn out in addition to your 90+ hours a week real-job are an
inspiration (and somewhat humbling to a congentile slacker such
as myself ;)

The four wheel ProtoBot is a skid steered platform?  Do you
run a separate PID controller for each wheel?

S.Rainwater has also used some beautiful laser cut parts for his
treaded robot.  The price is right, turn around is quick, and the
parts are first rate.

Ron Grant of the DPRG has built and refined a similar laser CNC device
in his garage (living room?) and made some really nice parts for
the group as well as trophies for our contests (anybody have any pictures?)
and this really seems like the wave of the future in one-off fabrications.


> Hello David,
> The robot is coming along.  Given the extreme hours working for "the man",
> there has been no progress in ~3-mo.  Leading up to that point the
> was good.  Today, in the studio is the first chance I am getting to really
> play in ever so long...
> Given the massive scope of the six wheeled robot project I decided to
> a simplified test platform to test out controllers, power supplies, motor
> drivers, software and algorithmic solutions.  The CAD depiction below
> the test platform. All of the circuit boards for this design are completed
> and in various states of population.  There are only 8 mechanical
> remaining to be fabricated prior to complete assembly, minus some final
> ops...
> I have also been taking advantage of Pololu's laser cutting service on
> project.  Given that I expect this one to get quite a bit of outdoor
> operation I have taken some time in an attempt to keep FOD out of the
> Some of the subassemblies are already assembled.  I will snap some photos
> this evening and post them to the web site.  It is all just a matter of
> time.  Work on the robot or document the progress.  I try to spend a
> reasonable amount of time on both but that is a struggle :)
> http://nikita.argia.net/kmaxon/proto_bot_cad27.gif
> The beautiful part about this robot is that the construction and
> are relatively simple compared to the 6 wheeled robot, and much of the
> technology from this robot test bed will lift directly into that one.
> fact then leads to the name of this robot, ProtoBot....
> Currently I do have pictures of most of the parts for this robot on my web
> site.   I'll try to finish that out tonight and post a few pictures of
> of the subassemblies as they sit today.
> Oh yes, some time back we chatted about the overall size of this robot.
> Unfortunately as the various components were sized it grew and grew.  The
> finished foot print will be ~24" front to back by ~30" side to side and
> a Z elevation of ~46".
> -Kenneth
> -----Original Message-----
> From: dprglist-bounces at dprg.org [mailto:dprglist-bounces at dprg.org]On
> Behalf Of dpa
> Sent: Monday, May 28, 2007 11:19 AM
> To: dprglist at dprg.org
> Subject: [DPRG] Re: Interesting robot to check out...
> Kenneth,
> Very interesting.  Are you contemplating a Linux powered robot?
> Any progress to report on your own 6-wheel robot project.
> best regards,
> dpa
> >
> >
> > Hello David and Group,
> >
> > I wound up on the west coast stuck working in Oregon for just short of 2
> > months.  Upon returning I have worked 96.5hrs this week and 92hrs last
> week.
> > Sigh... Not much time for robotics.  Tomorrow will be my first real day
> > head back to working on the robot.
> >
> > I thought I would take a minute and share the site I stumbled across on
> the
> > web.  If this has been seen before, then please  forgive the repost.  If
> > not, give this a look.  The articulated body is an interesting /
> > way to do things...
> >
> > http://linuxdevices.com/articles/AT8656331847.html
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