Building an Underwater self propelled detector

[Peg Leg]

I was just having a Far Out thought.
I watched my Grand son playing with a Remote Controlled car last night. I started thinking about WHY COULDN'T SOMEONE DO THE SAME THING BUT ON A LARGER SCALE.
Yes I know that there are ROVs but the price is OUTASIGHT.
Lets say that you were to take this concept down to where the average person could afford to buy or built their own. It would mean that you would have to seal everything so that water could not get to the electronics (not a problem). The bearing could be made of plastic so you could change them when they wear out. You would have to design this device so that you could add different electrontics as you needed like a Metal Detector, or a Side Scan Sonar or a camera WHATEVER YOU WANTED TO DO ALL YOU HAVE TO DO IT ATTACH THE DEVICE PUT IT IN THE WATER , LET IT SINK TO THE BOTTOM AND START FROM THERE.
I really believe that I can build one for less than $300.00 of course you need to increase the battery size and the size of the cables.
What do you think about this concept?
Peg Leg

 

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[Real de Tayopa Tropical Tramp]

HI: for shallow water it would pose no problems, the propulsion system might get a bit icky $ wise, but no problem, the electronics would be the big cost. Propulsion could be an inexpensive trolling motor externally mounted. The usual reverse/forward is simple with the DC motor.

Directional control while static? Optimally you could use a compressed air propulsion system, by jetting /bleeding off the air in different positions on the unit, you could have full 360 degree control horizontally and vertically. The source of air could simply be the usual diving tank mounted externally, or even surface supplied through through the unbilical cord..

As for the case, I built one for underwater photography before they were available on the market out of Plexiglas. Worked nicely. Your robot could use the freely available small freon tanks as a base.

But there is far more to it than this. Have fun.

Tropical Tramp

 

[Cablava]

Cornelius

Wh not take Peglegs idea a lttle further and make it a radio controled ROV.

Seal a radio reviever package on the Vehicle to control it and use a wire supported fine coxial cable (Kevlar would be great but very expensive) or fiber optic to a floating antenna and use the remote control unit to drive the vehicle. There are so many cheap RC packages available to have camera control even tilt and turn among the normal controls.

There can be some fine advantages for not having to have the boat over the vehicle all the time. Or searching from the river bank. A fail safe would need to be incorporated to suface the vehicle if contact is lost. Lots of radio control aircraft have a 180 degree turn when the get out of range and fly back into the radio coverage.

And as you know some sort of humidity control in the electronics box, Maybe a re-useable silica gel chamber, which can be quickly removed and put in the oven to dry out.

If it could be done I see many advantages in the shallow search.

And if you have an idea for getting the signals to the ROV through water that would be an amazing thing and probably be very profitable.

 

[Cablava]

Cornelius

I hear what you are saying, and for you its a personal challenge for your own purpose. But the ROV and AUV"s need to move into this area for the future, eventually there will be deep water solutions to these problems.

Check out this project, cost a lot more then your project but it's the way the industry is moving.

http://www.bluefinrobotics.com/cost.htm


Mike

 

[Cablava]

You might want to follow the ROV competions

http://www.marinetech.org/rov_competition/index.php

 

[GorskiDvr]

www.videoray.com look at the "Scout"
www.seabotix.com "LBV 150" <------- My favorite !

If thats still out of your range , it still gives you some insight on options & accesories..........

Couple more but beyond me .....
www.jwfishers.com
www.sharkmarine.com

 

[Real de Tayopa Tropical Tramp]

hi: Air jet control is very inexpensive, easy to construct, almost fool proof, and requires no electrical power, and minimal maintenance. It would give full pitch, yaw, and directional control.

Alternatively the jets could be driven by an electrically driven internal water pump which could be utilized with power from the umbilical cord/surface.

This limits the motor power requirements to one, internally or externally.

Tropical tramp

 

[mnm]

Freakin whacked !!!!

 

[Real de Tayopa Tropical Tramp]

=Cornelius ]
Tropical Tramp . Where can you get these air-jets ?
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Construct them yourself, calculations are not difficult, and the energy needed to move the ROV under water is at a minimum.
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How do I controll the forward - stop- backward revolutions of the prop ?
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With DC trolling motor, for example, merely reversing the polarity will do it. The existing control that comes with the trollling motor works nicely.
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Where does my exhaust air go to ? If the air goes to the outside I must work with at least 4 Ata .
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Correct, but since you only need a small nudge from time to time while at a "Static" condition, the usage is minimal. A small compressed air storage tank would last a long time since at low to hi forward or reverse speeds, the normal configurations will give adequate control through rudder or aileron configuration which can be driven by simple servo motors.
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If I use a separate electrical motor to work a compressor
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Only IF you used a water pump for your thrusters reactive pressure instead of air, in which case they would be supplied by the umbilical cord using surface power, hence indefinite underwater time.
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would it not be better to drive the props from the electromotor to start with ? How much electronics do I use to controll the desired motions ?
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Minimal, forward and reverse electric motor control would be nothing more than a physical adaption of the original control that comes with the trolling motor, nothing else to buy. The thrusters could controlled by any small low voltage electrical on/off valve, any number of which are on the hobby market or home aquarium supplies. They are Merely turned on for a small period of time according to needs.
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How long does a tank of air lasts when I use 4 Ata ? Just a few questions that make me wonder
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See above. Since I have no idea as to the bulk /weight of the finished unit, I cannot give you any solid data, but it should last quite a long time. since it is only used intermittently.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. My ROV is doing exactly what I want it to do , at a depth determined by the material I am using . No electronics to go hay-wired . The downtime is unlimited , and there is full motion controll . Show me a better way and I will try to build it .
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I am not in any way suggesting an improvement over your unit, which obviously works very well, I am only suggesting a simplified and extremely cheap alternative for Pegger to think about. In this configuration, the basic camera movement would be controlled by positioning the ROV. Of course one can also use one of the inexpensive miniature cameras with a movable mount which are now available for under $100 US.

p.s. A remotely controlled release for an external weight would be useful since it anything happened, you could release the external weight and the unit ,now having positive buoyancy, would surface by itself for recovery. This would be an automatic recovery feature in case of an electrical failure.

Tropical Tramp

 

[Peg Leg]

Gentleman,
You have ALL really given me TONS great ideas.
Thanks
Peg Leg

 

[macblastr]

you can use bildge pumps also to thrust with

 

[macblastr]

here is a link for the truely bored like me:

http://techreport.com/forums/viewtopic.php?t=31609

 

[Real de Tayopa Tropical Tramp]

[=Cornelius ]
Air - jets = construct them yourself
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Actually not difficult, a few simple experiments and calc. will give you the correct dimensions for the particular project.
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Well , a hydraulic motor works with pistons or vanes . The same will go for a air propulsion motor
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Agreed, but this would require a large pressure tank with obviously limited time unless you go via torpedo type motors which are prohibitively expensive. Also this would give more moving parts and expense.
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Again what do you do with the exhaust air .
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Exhaust it into the surrounding medium, this is what gives it a reactive momentum.
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Do you use an air regulator ?
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One could use an old mouth regulator for creating a set pressure above the ambient ATM
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Since the outside waterpressure could be 4 Ata , what would your working pressure be ?
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Whatever your calc, and tests show that is required. This would depend upon many factors. Obviously what would be required or a small ROV would not be suitable for say the Queen Mary.
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Now , tell me are you using jets or are you using a trolling motor ?
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Both, the trolling motor for longitudinal movement, and the jets, for axial and vertical movements.
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Reversing polarity with a DC Motor is well known .
Using additional servo motors etc etc . does not make the contraption simpler . It takes more electronics while not making the operation any better .
**************
Agreed, but there basically would be only one motor, the trolling motor. All of the other movements would be controlled by perhaps (4) small electrical on/off valves of low voltage.
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The movement you are after should be a constant motion , either forward , reversed or stationary .
***************
Quit correct, except the jets would control the axial /vertical movement while STATIC, On occasion you might wish to leasurely examine something up close for a period. You cannot do this while moving forward or backwards.
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A remote controll to drop a ballast weight is not necessary when you make your ROV slightly positive buoyant . It will pop to the surface when anything fails while it only takes a little trust to send her down .
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Again correct, but if you are hovering in a static condition examining something closely, you no longer have this submerging thrust effect so would bob up to the surface. In my demonstration the ROV would be "slightly" negative. because of the disposal weight. In the case of extreme recoverability, the weight could be attached to a Strong breakaway line to be recovered separately.
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When building a ROV think about what you are doing , and think about what you want it to do . Keep it as simple as possible while not giving up on all the things you want it to do
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Again agreed, precisely what I am proposing for El Pegger to consider..
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Before you start building , plan ahead . It took me three months before I touched any material . Do away with electronics where you can ! It will only give you trouble . Don't make any shortcuts , they don't work in the long run . When you start building do a nice job . Finish evrything like factory made or don't start this project . It is still a nice project if you take your time to do a nice job . The final result will be something you can be proud of and which is the same as one that is factory made . If you are not handy with tools , don't start or you will end up with some junk . Cornelius
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So far I see no disagreement between us, only in how to achieve the requred results at min. expense.


Tropical Tramp

 

[Peg Leg]

I have seen fan type devices on a Bathsophere to provide movement in any direction you wanted to go.
There are a great number of water proof fans on the market that are very small but big enough to provide the movement you would require in any direction including up and down.
Now if you were to connect a UW metal detector far enough away from all this wiring I think this would work pretty good. Also with this design you could create a small blower for dusting silt and sand. I would also attach a UW camera. You can get one from Harbor Freight for $99.95.
I was looking at a few of the toy vehicles my grandson has and I think that I can convert the drive motor to a single unit fan. This would mean that I would have 5 fan motors-1 for each direction and 1 for a dusting fan or small blower.
I can also use plastic shafts instead of metal shafts . The less metal the better (I would think).
For control I could use 2 joy sticks. I would also install some type of rheostat for RPM control.
All you would have to do is sit in a comfortable seat and watch your monitor.
Do you guys think this will do the job?
Peg Leg

 

[Real de Tayopa Tropical Tramp]

macblastr you can use bildge pumps also to thrust with
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HI, very good & true. Since the intake water would be at ambient ATM then the pumps would only have to supply the needed difference. This would hold true at any depth.

Tropical Tramp

 

[Real de Tayopa Tropical Tramp]

[=Cornelius ]
Tropical Tramp . I have a picture of my first ROV already on the forum ( My yellow soupmarine ) . As soo as the second one is ready I will send you a picture of it . In the meantime , keep on thinking it is good for the brain . Cornelius
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Thanks my friend, I agree wth you again on the brain.

Tropical Tramp

 

[Cablava]

A fluxgate compass is handy to have onboard so you know your heading, It makes flying them easier

I used to have a Small ROV which had a divers compass attached on an arm inside the cameras view, but this was never very accurate, I guess you would need to swing the vehicle to get the correct headings.

You could also attach a capillary depth gauage as well.

Simple solutions.

 

[Real de Tayopa Tropical Tramp]

True Cablava, just keep them in the periphyical view of the camera, either directly or by a see through front surface mirror as used in many cameras. .

Tropical Tramp

PERIPHYICAL SHEEH

 

[Peg Leg]

Actually what I am trying to build is a UW remote controlled metal detector.
The water has "0" vis so a camera is useless.
The water depth goes from 2.5 feet during low tide to 6.5 feet during high tide and sometimes reaches 7 to 8 feet.
I believe that with a Remote controlled device with a 10 foot very thin antenna that I can operate this device from my boat.
This device will have to weight enough so that the tide will have no effect. The antenna will have a orange flag attached so you can see which direction it is going.
I think the the whole unit must be encased with a round nose made from fiberglass.
Just thinking as I go along.
I do not believe that anyone except Dinkydick has worked in this type of environment so I have to play it by ear and go one step at a time.
In fact with the right Metal Detector you may not even have to go all the far underwater?
Peg Leg

 

[Real de Tayopa Tropical Tramp]

=Peg Leg

Now if you were to connect a UW metal detector far enough away from all this wiring I think this would work pretty good.
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Agreed.
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Also with this design you could create a small blower for dusting silt and sand.
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This would require a counter force, where would you generate this?
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I would also attach a UW camera. You can get one from Harbor Freight for $99.95.
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agreed.
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I was looking at a few of the toy vehicles my grandson has and I think that I can convert the drive motor to a single unit fan. This would mean that I would have 5 fan motors-1 for each direction and 1 for a dusting fan or small blower.
I can also use plastic shafts instead of metal shafts . The less metal the better (I would think).
For control I could use 2 joy sticks.
******************
A kiddies complex joy stick for net games would work just nicely, normally one would be enough with the triggers and buttons. Stick movement--> forward and backwards for the vertical components, left & right for the axial rotation, forward and reverse speed by a progressive trigger on the stick, (directional thrust, forward and reverse, contolled by a switch on the master panel in the boat, button for releasing the weight also on the master panel in the boa. Camera and dusting controls are also located on the master panel.
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All you would have to do is sit in a comfortable seat and watch your monitor.
Do you guys think this will do the job?
Peg Leg
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Have fun and make $$$$$$ my friend. However remember that radio control will induce many more problems, a simple umbilical cord will handle your problems nicely, also allow you to retireve it in the event unforeen problems arise. Incidentally I question your remark on the tide having no effect, unless it is designed as a bottom tractor.
Trropical Tramp