[chbot] Balancing robots

[John Stowers]

On Tue, Oct 21, 2008 at 12:41 AM, John Stowers <john.stowers at gmail.com>wrote:

>
> 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.
>

wow, too many references there. Too late at night.


>
>
> 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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>>
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