[chbot] Balancing robots

[John Stowers]

On Tue, Oct 21, 2008 at 12:27 AM, Michael Pearce <mike at kiwacan.co.nz> wrote:

> > This is a level of stability and control not achievable with simplistic
> PID
> > or Fuzzy controllers.
>
> Actually the Segway used a good number of dsPICs to do it all.... so
> not as much processing power as you may have presumed.... (Note: dsPIC
> is _NOT_ a dsp- it is a 16 bit digital signal Controller up to 40MIPS)


I wasn't referring to simplistic in the computational complexity sense, I
was referring to it in reference to the theoretical foundations of the
approaches.

Was definitely in the 2007 version.... may be different now.


Cool, thats actually quite interesting to know. I wonder what drove their
decisions to go with the dsPICs.

John


>
>
> Mike
>
> On Mon, Oct 20, 2008 at 1:11 AM, John Stowers <john.stowers at gmail.com>
> wrote:
> > This was created by Dean Kamen, i.e. Mr Segway. I expect it uses some of
> the
> > control technology inherited from that project.
> >
> > Presumably, like the segway, it uses one or multiple voting, optimal
> state
> > space controller/s.
> >
> > This is a level of stability and control not achievable with simplistic
> PID
> > or Fuzzy controllers.
> >
> > John
> >
> > On Mon, Oct 20, 2008 at 1:34 AM, Charles Manning <cdhmanning at gmail.com>
> > wrote:
> >>
> >> Pretty neat.
> >>
> >> I think there are a few things which really help keep this thing stable:
> >>
> >> 1) Moment of inertia.  A heavy item placed relatively far from the
> wheels
> >> is far easier to balance than a light one. That's part of the reason
> Hanno
> >> has the batteries on the top of the pole of his robot . Having an object
> the
> >> size of a human helps.
> >> 2) Relatively unlimited budget. Hanno is trying to make a cheap consumer
> >> item while these flash wheelchairs cost many thousands.
> >>
> >>
> >> Some horizontal reference, typically accelerometers because they are
> >> small, cheap and reliable, need to be part of any gyro-based solution
> >> because gyro sensors give you the rate of rotation and you need a
> horizontal
> >> reference to cancel out any offset (normally done in a Kalman filter).
> If
> >> you don't cancel out this offset then the machine would seem to be
> slowly
> >> rolling.
> >>
> >> -- Charles
> >>
> >>
> >>
> >> On Sun, Oct 19, 2008 at 5:23 PM, QtuTrains <Howard at qtutrains.com>
> wrote:
> >>>
> >>> If you think Hanno's balancing robot is interesting just take a look
> >>> at this:
> >>>
> >>> http://www.powerchair-review.fsnet.co.uk/ibot-4000-transporter-full-
> >>> review.htm
> >>>
> >>> The manufacture's site is http://www.ibotnow.com/ but I couldn't get
> >>> it to respond when I looked.
> >>>
> >>> Its a wheelchair that can rise onto two wheels and balance with a
> >>> person sat in it.
> >>>
> >>> It can also climb stairs!
> >>>
> >>> We saw one today at the Canterbury museum (not an exhibit!) and the
> >>> owner said it was the only one in New Zealand.
> >>>
> >>> It looked amazingly stable - much less oscillation to keep upright
> >>> than Hanno has achieved thus far. Naturally it uses gyroscopes for
> >>> balance, perhaps accelerometers too but the owner wasn't too much
> >>> into the technical details.
> >>>
> >>> The point of balancing is improved manoeuvrability and visibility
> >>> through increased height which was obviously useful in the museum.
> >>>
> >>> Howard
> >>>
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> >>
> >>
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> >
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>
>
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