[Dprglist] Hovercraft for RoboColumbus, sonar mapping of entire arena

[Ed Paradis]

I recall using that style of toy hovercraft as a kid and they _were_ very
hard to control manually, but fun. I wonder what modern gyro-stabilized
controls would be like.  I recall them having plenty of control
orthogonality despite the fan positions, lots of lag in direction changes,
and short battery lives. Lag in direction change was probably due to
insufficient thrust for its weight. Low battery time was due to the use of
NiCd batteries. LiPos would improve several parameters. You might eat all
that weight savings in the payload of your autonomous control, however.
High quality ducted fans were available in the RC plane space, when I last
looked a decade or two ago.

Ed

On Wed, Dec 7, 2016 at 8:51 PM, David Anderson <davida at smu.edu> wrote:

> John,
>
> I have a TYCO toy hovercraft:
>
> http://www.geology.smu.edu/dpa-www/robo/firefight/hovercraft.gif
>
> Or rather had one. I took it apart to use one of the blowers to extinguish
> a candle for the Trinity Firefighting Contest, from the before time.  Just
> an observation: They are very hard to control.
>
> As to Steve's 3 questions, you don't fit the criteria because you don't
> hold yourself out as an expert on robot building.  ( More a devil's
> advocate, if I may be so bold.  :)
>
> Quite the contrary, you know what you know.  Which is a trait much to be
> envied.   Plato would be proud.
>
> cheers!
> dpa
>
>
>
>
> On 12/07/2016 10:18 PM, John Swindle wrote:
>
> Guys and gals,
>
> Just to let you know I figured out my mistake:
>
> I wondered whether twin-rotor caged "drones" (what a terribly mis-used
> term) and Batmobile-inspired quad-rotor wheeled gadgets, that reduce
> battery drain by rolling most of the time, would be appropriate
> RoboColumbus platforms.
>
> Then I realized that my concern was marsh and high grass, and a simpler
> solution already exists: a hovercraft.
>
> I can't carry much stuff on a hovercraft, and hovercrafts expend energy
> all the time. But a hovercraft meets Dave's definition of a robot that is
> be able to rotate about its center (if it is so designed).
>
> I don't want to build any mechanical stuff anyway, so I don't know why I
> think about this stuff.
>
> If I can map the trees in the arena in one or two failed passes, along
> with the allowed walk-around with instruments before the contest runs, and
> then have a race to the cones on a third pass, using omni sonar, then that
> would be interesting to me.
>
> Mapping with sonar at 450 feet is almost impossible at high frequencies
> due to massive losses in the atmosphere. But mapping at, say, 100 feet may
> be enough to map the outdoor arena, and stitch the map together. Wobbling
> the mics three feet one way, and three feet the other way, staying within a
> four-foot envelope, would work, at least in simulation.
>
> I am not sitting at an armchair right now, but I nevertheless fail ALL
> THREE of Steve's questions!
>
> But one of the Neatos just jabbed me. So it's time for me to move out of
> the room. (It's fun to watch two of them jousting for position.)
>
> Later,
> John Swindle
>
>
>
>
>
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