Alt-BEAM Archive

Message #06058



To: beam@sgiblab.sgi.com
From: Ripter01@aol.com
Date: Mon, 13 Sep 1999 01:11:34 EDT
Subject: [alt-beam] Re: hello?


I got your message



6059 Tue, 14 Sep 1999 16:04:37 +0800 [alt-beam] Reversing Photovore? "BEAM" "Zulu35"
content-transfer-encoding: 7bit



hello all..,
been thinking about building a reversing photovore... i came up with this
circuit... haven't tested it yet.. thought i would get some feedback on
it.. btw, its my first :-)

attached is the circuit diagram., and the bot layout.



here is a truth table i used to help me in the design...

P1 - 4 ARE Photodiodes used to detect light,
Pe1, Pe2 are used to enable either forward or reverse operation, meaning..
if a light source comes from either due east or west of the bot, the bot
would not move. (prevents the motor driver from "locking" the motors)

M1, M2 are motors connected to a Bridge circuit.



P1 P2 P3 P4 Pe1 Pe2 M1 M2

0 1 0 0 1 0 0 1
1 0 0 0 1 0 1 0
===========================================================(FORWARD
OPERATION)
0 0 1 0 0 1 1 0
0 0 0 1 0 1 0 1
===========================================================(REVERSE
OPERATION)

Theory of Operation

P1, P2 are used to control the bot's forward light seeking abilities while
P3 and P4 are used for the reverse.
when P1/P2 detects light, the bot will move much like a photopopper towards
the light source. the reverse is also true.

however if light comes from either the 3 o'clock position , or the 9
o'clock position, either ( P1, P3) or (P2, P4) will turn on. as these
outputs are connected to a H bridge, it would cause the motor to "lock" or
brake. thus, i included Pe1 and Pe2 . these 2 P.d.s are connected to an AND
gate, together with the outputs of the P.D.s. this way, unless Pe1 or Pe2
is activated, the bot would not move at all.

heh heh now comes the problem... is there a way to increase the
voltage/current of the P.D. to provide the signals? i would need P1- P4,
Pe1, Pe2 to provide enough current/voltage to drive the AND gates and the
AND gates to produce enough current to drive the bridge circuits.

also, would it be feasible to drive this bot using a solarcell, or would it
be better to drive it using batteries? i have plans to make this bot follow
heat in future and, any ideas on how to add tactile sensors?

rdgs


Zulu






The Difference between interest and committment
is that when you are interested in something, you
do it only when its convenient. When you are
committed to something, you accept only results,
no excuses ----- Kenneth Blanchard -----




Attachment: lAYOUT.bmp


Attachment: pV.bmp

Home