Just The Start

[Private reid2]

Right, so i thought that i might build a underwater bot 
So, I have a little plan, but im not to sure how to go around the whole idea
see #1 i have to waterproof motors...not servo's but motors
Infact i gotto waterproof the whole thing...but thants not the main problem. i know how im going to waterproof it.
See, it's function is to practically "crawl" around water, sinking, floating, following any current that could be there
it will measure depth by either Sharp IR or a bumper switch (im thinking IR)
And objects IR or sonar (but can sonar see past plastic it's been pushed against? Or IR for that fact?)

Oh, well take a look...

[AndrewM]

IR goes through alot of plastics that normal light does not pass through, including some black plastics.  Unfortunately, the only way to know for certain is to give it a test.  Sonar I don't know about, but as it is sound I would imagine that some plastics would not hinder the pulses.

I am not sure how well IR would work underwater though as the light dispersion of water might cause problems.  Maybe Admin can chime in here.

[shlodo]

I think IR would work, interesting project tho
So by ur diagram can the bot move in all xyz direction?

[Private reid2]

with the right programing, yes.
all direction

Yer, ill use IR...i might enter it into the compition (if i finish it on time)

But ill need a motor driver that supports 4 motors

[shlodo]

Just get two motor drivers

If u need any of that kinda gear I am a distributor (Australia) for www.inexglobal.com
Chechk out these drivers:

http://www.inexglobal.com/products.php?type=addon&cat=app_motor&model=zxdcm2

http://www.inexglobal.com/products.php?type=addon&cat=app_motor&model=zxmotor3a

I use them they are good 4 high power apps.

Let me know if u need any gear:   [email protected]

[bukowski]

Low freq sonar has no problem going through rubber. On navy ships they use a pressurized rubber bubble to hold the electronics for the passive and active sonar. I have no idea about ultrasonics.

[paulstreats]

Maybe just some photoresistors would work. If say your submersible craft Had some cool green/blue lights that it flashed on and off, then the photoresistors would pick it up if its reflected off anything

[Private reid2]

ok, thanks alot, all of ya
im starting to have dreams! about this robot! 
Normal or not?
Na, im just excited! 

[Private reid2]

Do, i have to have a motor driver?
Can't i just use a H-bridge?

[Rebelgium]

Do, i have to have a motor driver?
Can't i just use a H-bridge?

motor driver = H-bridge

[Admin]

Sharp IR sensors can see past glass and many types of plastic. I've tested it through several feet of water and it worked fine.

For sonar, you'd have to hack those fish finder sonar. I bought one but never found the time/motivation to hack it . . .

[Private reid2]

yer, i thought a fish finder would be a good idea, ill search google

[Private reid2]

Wait!

i was thinking. Infa Red doesn't like working outside, right? Is that because of the UV light?
Or IR
Because neither IR or UV travels through glass windows and therefore IR works fine indoors!

AM I RIGHT?

[bens]

AM I RIGHT?

Not quite.  Unless it's been specially treated, glass is typically transparent to IR.  Also, UV is a completely different part of the electromagnetic spectrum and does not interfere with IR sensors.

IR sensors don't work well outside simply because the sun puts out a lot of IR light, which means there is a lot of background IR noise in which real IR signals tend to get lost.  For example, pretend you are outside on a sunny day and a person 100 yards away is holding a candle.  Do you think you'll be able to easily tell if it's lit?  Now let's run the same scenario again at night.  This time do you think you'll be able to tell if the candle is lit?

Indoors, there's simply less IR noise (usually it's nowhere near as bright inside your house as outside on a sunny day, right?).  This isn't because IR doesn't come in through the windows, it's because only so much light can get into the house through the windows, and usually the light that comes in is light that's been reradiated from the atmosphere (and I don't think the atmosphere scatters IR light anywhere near as well as it does visible light).  If you have a bright square of light shining on your floor through a window, you will notice decreased performance from your IR sensors in this patch of light.

- Ben

[Private reid2]

oh, thank you alot !