Alt-BEAM Archive
Message #03572
To: Dennison dennlill@buffnet.net
From: Bob Shannon bshannon@tiac.net
Date: Sun, 23 May 1999 12:50:26 -0400
Subject: [alt-beam] Re: Rolling wheel design..Rollerbots (was: Star Wars Ep1...)
Dennison wrote:
> When making a rollerbot, one has to think of how the device will turn. We
> undersdtand the miniball phenonenom, where the shifting weight makes it go
> forwards. Many people suggested shifitng two weights for directional
> controll. This method doesn't actually seem like it would work very well. So
> I went back to the miniball. First, I decided to elongate the ball, as when
> it's entirely circular it's motion is far too random for good use. So I put
> a little strip of cardboard between the two sphere halves, that way it
> normally roles straight. To turn, I need to slightly tip the ball, using a
> weight with a short radius or swing, I can accomplish this.
Why not adapt the inertial turning mechanisim recently discussed here to pivot
the miniball towards the light source with a seperate SE, and then let the type
2
SE of the miniball provide the motive power?
I would have thought that the biggest problem of the miniball was its total
inability to deal
with uneaven surfaces, or to move up a slight hill towards the light!
> As the sides of
> the bot are circular, ( the halves of the miniball) the circumference is
> smaller, since it's smaller it's velocity is lower, so when the bot leans
> onto it's sides, it works like differential steering, where it sudenly
> doesn't turn as fast, and the bot begins to pivot around that point. in this
> fashion I steer. I've been working wth a weighted version, and as soon as I
> get my hextiles back, I'm going to work on a bicore version.
>
> Dennison
The neat feature of this is as it leans over onto its sides, the effective gear
ratio
drops in direct proportion to the now smaller contact area with the surface its
moving over.
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