DPRG mailing list archives: [DPRG] Re: DPRGlist Digest, Vol 44, Issue 14 BristleBot again

Sun Jan 13 10:22:33 CST 2008

Hi Randy,

Thanks for the explanation of the football toy!  I remember seeing one or
two during my childhood, but didn't know about the two clear plastic sheet
strips.  I think you're on to something here.

I didn't cut my bristles because I didn't think I could cut two of them
accurately enough.  I haven't been able to turn my catamaran bristlebot by
powering only one motor.  I do have an idea for another way to do it, but it
would be electrically much more complicated.  (Kind of link an ultrasonic
actuator works.)

Another idea arose during the RBNO.  The pager motors make my 'bot "hover"
pretty well with either motor spinning, so maybe attaching a fan blade to
each one would allow for some pusher-prop turning.  Not really elegant, but
it might be fun to try.

I'm going to try to make some sheet plastic "feet" to replace my
toothbrushes, kind of like the football player bases.  Thanks for the ASCII
art!

-Jeff

On Jan 9, 2008 3:15 PM, Randy M. Dumse <rmd at newmicros.com> wrote:

>  I was going to mention since I saw the video Jeff, I think the
> combination of some vertical and some diagonal bristles is what gave my
> Cross Action B BristleBot such speed.
>
> I see yours used nearly vertical bristles only.
>
> My childhood electric football players used two bits of clear plastic
> sheet strips. Forward, it had one strip, running from side to side (e.g.
> left to right of the player) set at an angle so the top of the strip was
> forward placed and the bottom of the strip was aft relative to it. The other
> strip in the back, also ran horizontally across the players bottom pad, but
> it was set in vertically, without a cant or direction to it. I was pretty
> sure this arrangement was what made the players always go (roughly) forward
> when the floor vibrated. (Man that thing was loud! Like a 60-Hz transformer
> hum feed into a megaphone.)
>
> Ascii art attempt follows:
>
>     ||  \\
>     ||   \\ player legs
>     ||    \\
> +-------------+
>  | player base |
> +-------------+
>    \         |
>     \        | <- strips of flexible plastic sheeting
>
>     ^       ^
> fwd strip, aft strip
> angled     vertical
>
>
> Anybody got ideas how we're going to put directional controls on these
> bristle bots yet? So far, there are varied reports on making catamarans turn
> by using only one motor, mostly not successful. To throw a mechanical
> weight, or bristle direction control seems problematic. Even micro servos
> seem too large, as big as the rest of the robot. We need smaller actuators
> than even that.
>
> Randy
> www.newmicros.com
>
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