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Offline rack2020Topic starter

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underwater project
« on: December 22, 2008, 05:22:40 AM »
I am a student, designing an Underwater Vehicle.
      I need the following parts:
         1. pressure sensor.
         2. temperature sensor.
         3. pH sensor or something that determines the acid content of the  water.
         4. sensor to determine the dissolved oxygen content in water.
         4. above all these things, i need some tutorials on about storing the videos captured by
             the camera and transmitting it after some time wirelessly in air(not through water).
             also i need to study how to display all the parameters and video at the receiving station...
           Can you suggest some ideas and tips. I will be very much glad in doing so.

Offline cooldog

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Re: underwater project
« Reply #1 on: December 22, 2008, 07:31:13 AM »
robot will rule the world and i will be building them
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Offline bulkhead

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Re: underwater project
« Reply #2 on: December 23, 2008, 04:09:52 AM »
Some questions: does the data from the sensors and/or video need to be viewed at the receiving station in real time, as the under water vehicle is moving?  What do you mean by "after some time" and why through the air and not water?

In general, you would probably hook up all the sensors to either a microcontroller or computer, which would either log the data and/or transmit it wirelessly (2.4GHz RF, bluetooth, wifi, etc) to the receiving station.  Since you will probably end up using some pretty obscure sensors, finding sensors with a USB interface and using a laptop/netbook would probably be the easiest solution.

Offline cooldog

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Re: underwater project
« Reply #3 on: December 23, 2008, 08:17:01 AM »
Some questions: does the data from the sensors and/or video need to be viewed at the receiving station in real time, as the under water vehicle is moving?  What do you mean by "after some time" and why through the air and not water?

i think he wants the it to store the video when underwater then when it surfaces for it to transmit. it is easyer to transmit data through air then water
robot will rule the world and i will be building them
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Offline rack2020Topic starter

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Re: underwater project
« Reply #4 on: December 25, 2008, 10:27:16 AM »
this is for bulkhead.... what cooldog said is correct.... it is difficult to transmit data wirelessly through water... so i want to record all the data at a particular depth and after sometime the robot should start floating over the surface to transmit the data collected at that depth.... now i want to know whether i need to have a new software to display all the data on a pc/laptop or is there any softwares available????
all the above are for my applications.... the real challenge is to control its motion which im working on it now....
I thank all those who had replied and i request you to keep suggesting some ideas.....

Offline bulkhead

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Re: underwater project
« Reply #5 on: December 25, 2008, 05:14:40 PM »
The simplest way to log data is just to a spreadsheet or text file; transmitting that wirelessly is a bit more complicated.  If you end up using a laptop or computer to log the data, the easiest wireless solution would probably be to just use wifi.  Does it really need to be wireless?

It may also be possible to use a microcontroller to do all of this; maybe someone else can weigh in on this option.

Controlling its motion does seem like a challenge.  Neutral buoyancy is very difficult to attain since there is a sort of unstable equilibrium at any depth.

Offline jamort

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Re: underwater project
« Reply #6 on: December 25, 2008, 10:00:22 PM »
The simplest way to log data is just to a spreadsheet or text file; transmitting that wirelessly is a bit more complicated.  \
Couldn't he use the printf function and then it would run off on a command prompt?
my english teacher once said, "dont talk about what you dont know in public...."

so I replied the truth, " Exactly why I dont ever talk about English."

Offline rack2020Topic starter

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Re: underwater project
« Reply #7 on: December 26, 2008, 06:44:55 AM »
it seems i may use rc232 latest microcontroller for this... im not worried about the application and communication now... anyway i also accept suggestions for it... i just want to have some study about the motion... any link or something simple will help me.... i hav tried many ieee papers but all consume bugs... i saw a book "build your own under water vehicle" by henry bohm... but i dont know where i can avail of it....

Offline rack2020Topic starter

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Re: underwater project
« Reply #8 on: December 26, 2008, 06:50:53 AM »
also is there any simulation software for this????

Offline jamort

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Re: underwater project
« Reply #9 on: December 26, 2008, 09:35:30 AM »
yeah theyve got these things called moisture sensors put on of them on it so when battery gets low use everything to get to the top and when the sensor senses nothing cut off... on problem it might sink...... add a sonar to so you can make sure theres nothing in front of it..... Ive seen hte iunderwater robot competitions and pvc is normally the thing they are made out of....
my english teacher once said, "dont talk about what you dont know in public...."

so I replied the truth, " Exactly why I dont ever talk about English."

Offline rack2020Topic starter

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Re: underwater project
« Reply #10 on: January 08, 2009, 07:48:18 AM »
Im back again having worked a lot.... now all i need is a propeller that can suck the water up so that my robot will move down.... but i dont know how much should be the rpm and also where can i get them for my robot.... my robot weighs about 5 Kg and its volume is 0.0108 metre cube.... any help??? Thank you....

Offline fuzzyt

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Re: underwater project
« Reply #11 on: January 08, 2009, 10:52:11 AM »
Im back again having worked a lot.... now all i need is a propeller that can suck the water up so that my robot will move down.... but i dont know how much should be the rpm and also where can i get them for my robot.... my robot weighs about 5 Kg and its volume is 0.0108 metre cube.... any help??? Thank you....

I would really like to see the work you've done.  Got any pictures or anything?  Maybe a quick writeup on how everything is put together? 

Offline Razor Concepts

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Re: underwater project
« Reply #12 on: January 08, 2009, 04:28:16 PM »
A tough part will be the wireless communication. A lot of signals (GPS for instance) don't work underwater, and WiFi signals get significantly weaker.

Offline dunk

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Re: underwater project
« Reply #13 on: January 09, 2009, 04:14:22 AM »
Im back again having worked a lot.... now all i need is a propeller that can suck the water up so that my robot will move down.... but i dont know how much should be the rpm and also where can i get them for my robot.... my robot weighs about 5 Kg and its volume is 0.0108 metre cube.... any help??? Thank you....
using a propeller to keep your bot under means you constantly have to run the motor to stay under.
a better way is to change the density of the bot so it sinks on it's own.
have a cylinder of air which you can compress. something like a motor driven bicycle pump.
when you want to go down you compress the cylinder so the buoyancy of the bot decreases and it submerges.
you can actually buy such devices on RC submarine web pages.

dunk.

Offline rack2020Topic starter

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Re: underwater project
« Reply #14 on: January 09, 2009, 09:41:37 AM »
Im back again having worked a lot.... now all i need is a propeller that can suck the water up so that my robot will move down.... but i dont know how much should be the rpm and also where can i get them for my robot.... my robot weighs about 5 Kg and its volume is 0.0108 metre cube.... any help??? Thank you....

I would really like to see the work you've done.  Got any pictures or anything?  Maybe a quick writeup on how everything is put together? 

im sorry that i cant say anything now... because im not sure whether my idea will work out... but soon i will get u know once completing the project fully...

Offline rack2020Topic starter

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Re: underwater project
« Reply #15 on: January 09, 2009, 09:44:48 AM »
Im back again having worked a lot.... now all i need is a propeller that can suck the water up so that my robot will move down.... but i dont know how much should be the rpm and also where can i get them for my robot.... my robot weighs about 5 Kg and its volume is 0.0108 metre cube.... any help??? Thank you....
using a propeller to keep your bot under means you constantly have to run the motor to stay under.
a better way is to change the density of the bot so it sinks on it's own.
have a cylinder of air which you can compress. something like a motor driven bicycle pump.
when you want to go down you compress the cylinder so the buoyancy of the bot decreases and it submerges.
you can actually buy such devices on RC submarine web pages.

dunk.

Hi Mr/Ms Dunk,
    i want my robot to be positvely buoyant... so i will use propeller to sail down... incase of any failure this helps me to recover my robot automatically... got it? so i just need the concept of calculating forces due to propeller and easy availablity of it in the market... thank u....

Offline dunk

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Re: underwater project
« Reply #16 on: January 09, 2009, 04:30:19 PM »
i want my robot to be positvely buoyant... so i will use propeller to sail down... incase of any failure this helps me to recover my robot automatically... got it? so i just need the concept of calculating forces due to propeller and easy availablity of it in the market... thank u....
2 things come to mind..
1st, you could put movable fins on the sides so when you are moving forwards you can direct the bot downwards. like the controll surfaces on an aircraft but in reverse.

2nd, if you want a submersible motor and propeller combination try looking for boat bilge pumps.

dunk.

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Re: underwater project
« Reply #17 on: January 15, 2009, 08:18:59 AM »
also is there any simulation software for this????
What would you like to simulate?

Offline rack2020Topic starter

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Re: underwater project
« Reply #18 on: January 22, 2009, 04:05:16 AM »
hi... im going to fix 3 blades to my motor and going to use it as propeller.... my 5 Kg robot should move downward with 0.1 m/s velocity. so how to choose motor rpm and its torque? it only gives rotational torque... but from that how do i know that torque is enough to pull my robot downwards with 3 blades propeller... my prop dia is 2 inches... also where can i get submersible dc motors for robotics or is there any readymade submersible propellers... kindly help... thank you...

Offline spykid99

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Re: underwater project
« Reply #19 on: January 22, 2009, 05:30:41 AM »
Hi about the control system
You would probably want to just learn VB or something and code it yourself
Other software needs specific signals and everything so just code it yourself
Spykid99
"Do not worry about your difficulties in Mathematics. I can assure you mine are still greater." ~Albert Einstein

Offline rack2020Topic starter

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Re: underwater project
« Reply #20 on: January 23, 2009, 05:00:27 AM »
please answer this... what is the relation between rpm of the spinning propeller and the thrust offered by it in the opposite direction?
imagine there is a propeller facing downwards attached to my 5 Kg robot. at what speed it should rotate in the reverse direction to pull my robot downward? where can i buy such a propeller in india that works in 12V dc? what specifications should i mention?

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Re: underwater project
« Reply #21 on: February 03, 2009, 05:11:09 AM »
Quote
please answer this... what is the relation between rpm of the spinning propeller and the thrust offered by it in the opposite direction?
It entirely depends on:
rpm
prop size
number of probs
prop shape

You'll just have to experiment . . .

Offline madchimp

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Re: underwater project
« Reply #22 on: February 03, 2009, 05:45:40 AM »
please answer this... what is the relation between rpm of the spinning propeller and the thrust offered by it in the opposite direction?

I would imagine it would also make a difference if you are operating it in salt or fresh water. Especially if you are looking for a fairly precise dive rate.

Offline rack2020Topic starter

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Re: underwater project
« Reply #23 on: February 17, 2009, 07:55:23 AM »
ok thanx for the reply... now i need a sonar that works in water... is there any waterproof sonar so that i can make a direct contact of it with water? note that i will connect it my microcontroller....

Offline Wizzard

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Re: underwater project
« Reply #24 on: February 17, 2009, 02:27:40 PM »
Most normal fish finders have a submersible transponder. Try Hummingbird or Orion If you just need depth you could use a regular boat transponder.

any pawnshop near a large body of water will have one usually.

Offline rack2020Topic starter

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Re: underwater project
« Reply #25 on: March 12, 2009, 08:54:05 AM »
well, time has come to thank all those who have helped me... almost 75% over... im just using LM35 temperature sensor and transmitting the temp value wirelessly.... the work that is remaining is to code my PIC16F877 micro to make it autonomous.... is there any tip on how to code it? I have to write coding for-
1. interfacing 4 DC motors to achieve horizontal motion (i use L293D driver IC for these)
2. interfacing a DC motor to achieve vertical motion (i use L298 driver IC for this)
3. store and transmit the stored temperature values....
Thats it.... hardly two weeks left... i have to finish my coding and test its running... finally i will post all my experiments and results.... Help me... Thank You....

Offline MrWizard

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Re: underwater project
« Reply #26 on: March 12, 2009, 02:52:59 PM »
About your buoyancy. After a certian dept your robot will not be buoyant anymore. You should always have "rescue" option like a Co2 balloon lift or drop-weights. which will open/drop after a certain time or certain depth, so rescue the bot is easy. Also there are very mighty pressure forces, be sure to proof your design.
You can use bluetooth for data transmit , bluetooth saves the battery and a range a 5-100 mtrs is possible in open air (bluetooth 1.1( 1-10mtrs/yards) or 2.0 (1-100mtrs/yards).
Perhaps program a switch that bluetooth will only function in open-air, when it hits the water it will stop transmitting. (saves battery).

You could use a compass (instead of GPS) module,speedo-meter and a depth-meter so you can move around a little with the bot.

 :o  There are some diving-computers around like delphin or suunto , they have almost all the sensors you will need. Just the price....
« Last Edit: March 12, 2009, 02:54:32 PM by MrWizard »

Offline rack2020Topic starter

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Re: underwater project
« Reply #27 on: March 18, 2009, 01:51:48 PM »
can i use IR sensor to avoid obstacle underwater? will that work?

Offline Admin

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Re: underwater project
« Reply #28 on: March 25, 2009, 01:05:55 AM »
can i use IR sensor to avoid obstacle underwater? will that work?
yes, Sharp IR works underwater.

Offline rack2020Topic starter

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Re: underwater project
« Reply #29 on: April 02, 2009, 07:03:34 AM »
This s a great news for me... But can u be more clear about u using the word 'sharp' there? Because i hav bought IR sensors for line follower in the local market. It had just ordinary 2 IR leds (one transmitter and other receiver). Now can I use that one underwater or R u meaning some more advanced one? If so can u just tell me what is it & where i can get it in India or probably at chennai? If u paste the link here, it will be very much helpful... Thank u....

 


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