Alt-BEAM Archive
Message #13805
To: "'beam@sgiblab.sgi.com'" beam@sgiblab.sgi.com
From: Wilf Rigter wilf.rigter@powertech.bc.ca
Date: Fri, 21 Apr 2000 12:51:19 -0700
Subject: re: silence bot
Active silence (wide band sound cancelation) is not as simple as you think.
There are only a few applications that I am aware of using this technique.
Active cancelation headphones reject all external sound allowing listing to
your favourite CD in very noisy environments. Mics on the headphone cups
pick up the external noise, amplify and invert it, and add it to the audio
stream.
Another application is an active acoustic muffler for automotive engines.A
special DSP is used which shifts every frequency by 180 degrees. This drives
a "speaker" at a junction in the exhaust pipe precisely canceling the
exhaust noise. Altenatively a muffler can be "tuned" for that signature
sound. The demo of this is scary to hear : A Harley chopper with a sound
on/off switch or a Moped on steroids.
wilf
William Cox wrote:
> Hey all,
> I been thinking about noise cancellation. This might be an interesting
13806 Fri, 21 Apr 2000 12:50:18 PDT Re: efficient launcher?again beam@sgiblab.sgi.com "sebastiaan van Vliet"
Just popped in my mind: Why not electrolysing some water and ignite shooting
the hook away?
>From: "Phillip A. Ryals"
>Reply-To: beam@sgiblab.sgi.com
>To: beam@sgiblab.sgi.com
>Subject: efficient launcher?
>Date: Wed, 19 Apr 2000 11:55:33 -0500
>
>I had this groovy idea, but I'm not sure if it can actually be done
>efficiently. Maybe someone could give me some pointers?
>
>I was thinking that it would be cool to implement a grappling hook type
>system to allow a robot to get over large obstacles. It would require
>some type of winch system that retracts the line, and I think this has
>already been done with 'window washers'. But what about a launcher? I
>really don't think there's an efficient way to do it with a solenoid or
>motor... I just don't think a beam cicuit could really launch anything
>very far. I think it would need to be a system where a gear motor
>wiches the hook onto a spring. Then, you would need some sort of quick
>release to get the full force of the spring. I think a big problem
>might be the friction of the line used. That might be overcome if the
>hook had some weight though.
>
>
>Is this all just wishful thinking? It sounds like a LOT of trouble to
>go to, but I think the effect would be pretty cool. Set the bot in
>front of a wall three times it's height, and watch the bot climb it.
>
>
>Any ideas?
>
>
>-phillip
>
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