Alt-BEAM Archive
Message #12936
To: beam@sgiblab.sgi.com
From: BUDSCOTT@aol.com
Date: Sun, 2 Apr 2000 17:54:36 EDT
Subject: [alt-beam] Re: Reverser
Thanks! i was thinking it would work like that but i wanted to be sure before
i did something foolish!
-Spencer
<http://www.botic.com/users/beamstop>
not a robot scientist
not a college major
not a grad student
not a professor
not a very organized person
just Spencer (isn't that impressive enough?)
12937 Sun, 2 Apr 2000 17:53:16 EDT [alt-beam] Re: Almost Complete Walker beam@sgiblab.sgi.com BUDSCOTT@aol.com Hey, tell him congrats for me! I like to hear people succede with walkers,
they can be a pain, i know that cause i'm in the works on one as well. That
circuit is actually pretty succesfull, however, i did screw it up the first
time! Maybe you should send some pictures to beambotix (i was tempted to
offer my page, but i'll let beambotix take the monopoly!). What kind of
motors did he use? What kind of power? How about the sensors? I hope you guys
have good luck with your next walker (if he's anything like me, he'll have
already thought of that!) Good Luck!
-Spencer
<http://www.botic.com/users/beamstop>
not a robot scientist
not a college major
not a grad student
not a professor
not a very organized person
just Spencer (isn't that impressive enough?)
12938 Sun, 2 Apr 2000 17:58:09 EDT [alt-beam] Yahoo Chat! beam@sgiblab.sgi.com BUDSCOTT@aol.com Is there a yahoo chat tonight? i'll be there either way, or if you don't have
yahoo, try Instant messenger!
-Spencer
<http://www.botic.com/users/beamstop>
not a robot scientist
not a college major
not a grad student
not a professor
not a very organized person
just Spencer (isn't that impressive enough?)
12939 Mon, 3 Apr 2000 11:12:25 +1200 [alt-beam] Re: Wisker Circut "Andrew Hooper" Wilf,
Thanks for the feedback.
>Nice idea to use a piezo element for input, I imagine that the solder joint
>is a little fragile. Tried a little epoxy?
>But I have some questions about the circuit.
The solder joint actually ends up prety strong, its strong ehough that is
you
really force it the element will crack, and the bronze wire will bend before
the solder joint broke (tried it) and the pezio still worked while cracked.
I have not tried epoxy, cant see why that would not work other than for
a strong bond you will need to place a reasonable dolop of epoxy, this
could alter the flexibility of the transducer and therefore alter the
sensitivity
however saying that it may give you a nechanical form of noise reduction
and eliminate some of the triggering caused by the motor vibration.
>1. Do you need a transistor and the HC buffers?
No, just the transistor worked, the HC buffer was there to shape the pulse
this circut also cacts as a little bit of protection for the pic, if the
element
gets a BIG shock it can generate really high voltages that will pop a pic
>2. Can the piezo be directly (with a series resistor) connected to an HC
>input?
Yes, but its not seems as sensitive, when i tried it i really had to tap the
feeler prety hard to get a response.
>3. could you go straight (with a series resistor) from the transistor into
>the PIC input?
Yes and No, I did try this BUT was a little concerned about spikes, i also
tried to put a zener across the element but it chanegd the sensitivity, also
the sensitivity was not as good as it was with the circut.
The circut is so sensitive it triggers it i drop a hair on it, yet its still
not
triggering to vibration, eg you can tap the desk or the protoboard and
get no trigget, but the second you touch the wisker (even with something non
conductive) it triggers.
>4. What size capacitor do you use on OUT?
I did not use one for this, Erm.... should it be decoupled with a cap?
>5. Try a different diode connection to give a dual time constant : fast
>charge/slow discharge
Will try that, that was one of the problems i was having, sometimes the
trigger time is so fast that the pic will not respond, if i can slow the
discharge
down that should solve that problem. :) thanks.
>> -----Original Message-----
>> From: Andrew Hooper [SMTP:andrew@best.net.nz]
>> Sent: Saturday, April 01, 2000 6:53 PM
>> To: beam@sgiblab.sgi.com
>> Subject: Wisker Circut
>>
>> I have tested it and it seems to work on a PIC based robot, have not
>> tried with a uCore yet.... thats the next job on the list :)
>>
>> If anyone sees any problems or can see a better way of doing this
>> please let me know.
>>
>> The Peizo mods can be found at....
>> kiwi.forge.cc/bots/
>>
>> Regards
>> Andrew << File: feel02.gif >>
Home