Alt-BEAM Archive
Message #04885
To: beam@sgiblab.sgi.com; James Anderson anderson@cfht.hawaii.edu
From: Bruce Robinson Bruce_Robinson@bc.sympatico.ca
Date: Sat, 26 Jun 1999 23:40:16 -0400
Subject: Re: Photopopper problems
> James Anderson wrote:
> >
> > I finished my first photovore yesterday, ... the problem I'm
> > having is that [the wheels] only turn when not touching the ground ...
>
> and JVernonM wrote:
>
> > The problem you are having is with the torque strength of pager motors,
> > i.e., they have none. ... In your set up, you are better off to remove
> > the wheels and run the bot on the motor shafts.
>
> and James Wilson wrote:
> 1
> > My advice is to loose the wheels and use shrink tube on the shafts ...
>
> This advice is exactly right. With large diameter wheels driven directly
> from the motor, your torque demand goes way up. Running directly on the
> motor shafts (covered with heat shrink tubing for traction) should solve
> your problem. The only difficulty is if you don't have enough ground
> clearance to do this.
>
> An equivalent method is to use your hard rubber wheels as "idlers".
> Mount them on axles so they spin freely, then place your motor shafts so
> they run against the surface of the wheels. Steve Bolt's robot,
> "Willie", is an example of this method (even though he isn't a
> photovore). Take a look at:
>
> http://www.xs4all.nl/~sbolt/e-andere_robots.html
>
> To see the motor-wheel arrangement. Except for a small friction loss,
> this is exactly the same as running your motor shafts directly on the
> ground. And it doesn't matter what size your wheels are -- they are just
> idlers.
>
> Take care,
> Bruce
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