FishPi - automated surface vessel.


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by viciouspenguin » Mon Mar 05, 2012 12:23 pm
I"ve hit upon the idea of an autonomous trans oceanic surface vessel.

the barebones idea revolves around a solar powered model boat, controlled and navigated using the RPi.

I understand there maybe other guidance systems around but they dont seem to offer the holistic capabilities of the RPi.

I"m obviously only at the thinking stage at the moment, and I shall keep everyone informed of the projects progress.
FishPi: An autonomous drop In the Ocean.
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by st599 » Mon Mar 05, 2012 12:30 pm
viciouspenguin said:


I"ve hit upon the idea of an autonomous trans oceanic surface vessel.

the barebones idea revolves around a solar powered model boat, controlled and navigated using the RPi.

I understand there maybe other guidance systems around but they dont seem to offer the holistic capabilities of the RPi.

I"m obviously only at the thinking stage at the moment, and I shall keep everyone informed of the projects progress.



Sounds very interesting.

I'd love to throw some ideas around sometime.
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by vhori » Mon Mar 05, 2012 1:50 pm
That's what I thought...

I look forward to the cooperation.

Hori
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by Lynbarn » Mon Mar 05, 2012 2:49 pm
Do you mean to do something like this?

http://www.microtransat.org/index.php

Sounds like a great project.

There is a whole raft (sorry!) of automated transport-related tasks that the 'Pi could be put to - and they also make good educational projects too.

I quite like the idea of a hunter-killer sub for my local boating lake - but that's just me! :D
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by dannyboy1984 » Mon Mar 05, 2012 7:08 pm
I like this idea a lot. Would you have any communications with the vehicle to see where he's up to?
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by viciouspenguin » Mon Mar 05, 2012 7:58 pm
dannyboy1984 said:


I like this idea a lot. Would you have any communications with the vehicle to see where he's up to?



yes, and no.

my thoughts at the moment are to have a switchable (turn on and off) GSM/HSDPA/MOBILE module attached via usb. i would hope to have the module activated when it comes within one mile of land. once connected it can then upload gps location information etc. I think to have a connumications station onboard so it can work in the middle of an ocean might be too power hungry, and expensive plus theres the addtional weight, which i want to keep to a minimum.

the navigation system is essentially free range, i give it a destination and then it plots its own route. i will use a geotiff map which gives it range limits so i can have it avoid shipping lanes & land.

i'm trying to ensure it remains as low powered as possible, with any experimental modules powered on/off as and when required.

i'm looking at running it from a 70w solar cell which should give around 7v and 8apms, this should be plenty to drive the propulsion system, the RPi and any additional modules. if the power drain is too high then the drive system can always be turned off while measurements etc are carried out.

i've started work on fishpi.org as the project page. there isnt much there yet as i've only had an hour or two yesturday, and its being used to help run my train of thought so it might get a bit messy. expect a forum, and the usual blog once its up and running propperly.
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by gjs » Tue Mar 06, 2012 12:03 am
I'm curious as to why weight would be a major concern?  Also, would the power consumption of electronics like a RPi not be insignificant compared to that of the propulsion system?

Does this project have a practical aim/use or is it just to see what can be acheived?
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by PaulTech » Tue Mar 06, 2012 1:31 am
A quick look on ebay provided this example

http://www.ebay.com/itm/Newest.....2a13a5fe69

Not big enough for a 70W panel, but it might be enough to start testing.

Some of this type of boat also include GPS & SONAR so it may be worth doing some searching before building.

I realise your boat would be much larger for off shore work, and I am not saying buy and convert for the finished product, nerely this is what someone has already done and is selling now.
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by viciouspenguin » Tue Mar 06, 2012 9:09 am
weight is a concern because i will have limited power to push it around with. yes the RPi power use is very low compared to the propulsion system and thats why i"m looking at a 70w panel.

if i can keep all power needs below the 70w output this helps keep the size down, and it should in turn lower costs etc.

the baitboats while they look usefull are an expensive way in, for a test vessel, $450 odd is high. but i will have a look into it none the less, i might be wrong....

will it have any practical use? yes i hope so. theres no reason why i cant have an array of sensors on board, aslong as it all remains within the power capabilities i dont see why not.
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by Newbie » Tue Mar 06, 2012 9:37 am
If it's going to have a solar panel, you need to ensure it stays upright in very large waves (upwards of 40 feet high are possible in open-ocean Winter storms in the Northern Pacific) by giving it as large a metacentric height as possible (center of gravity as far below center of flotation as feasible).

I would make it a sailboat, which eliminates the propulsion power issue.  Sails and software are a _lot_ cheaper than batteries, motors, solar panels, etc., that are doomed to fail just when things are about to get interesting.  Wind and current data can be received via a variety of radio spectra and formats from HF to satellite.

Above a certain size/displacement, you will need to put lighting and at least a noisemaker (e.g., a bell) at/near the highest point in order to comply with international maritime law, not to mention common sense in nautical safety.  You should put your contact info plainly visible from as far away as possible (another good use of a sail :) so that, if it's not reporting its position, others who happen upon it can provide interim position/status updates.  Plus, when, not if, it dies, someone who finds it can at least tell you where they picked it up and you can arrange for its return (or, you get to make a trip to a potentially far-off, exotic locale ... most likely a dingy rat-hole of a port no one has ever heard of, or been heard from again ;)

Obviously, I'm intrigued by this project already, especially the retrieval trips! ;)
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by viciouspenguin » Tue Mar 06, 2012 10:11 am
i had thought about capsizing, and using a catamaran hull that would be an issue, mono hull not so much it could be made to self right etc. i dont plan on having it out at sea in thr winter months, i need to capitalise on the sun and the summer is best for that.

size, hmmm, i am aiming for no more than 1.5m x 0.7m. really i only want it as large as the solar panel.

which brings us to sails, i dont wanna :p it has been mentioned before by lynbarn, and there is already an established automated sail community. im looking to start something different, but i also accept that there may very well be practical implications that leave the idea dead in the water...

identification, rather than a sail, what about a flag, with say a QR code on it? naturally there will be information on the hull.
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by Ravenous » Tue Mar 06, 2012 12:03 pm
Have a look for the Wave Glider robot boats - by liquid robotics.  Saw it on the news a few months back.

(Fifth attempt to reply to this forum!)
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by viciouspenguin » Tue Mar 06, 2012 2:09 pm
i remember seeing something about them too, very clever design concept.

i found an autonomous submersible, not quite as long range but intetesting enough. they popped up while searching for a usb compass.

ocean server"s IVER2 http://www.iver-auv.com
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by gjs » Tue Mar 06, 2012 5:25 pm
viciouspenguin said:


weight is a concern because i will have limited power to push it around with.


This isn't really the way a ship works.  The power required to push it forward in the water is not directly related to it's weight but the hydro dynamic properties of it's hull e.g. you can make the hull twice as long, which will carry twice as much weight, but will not require twice the power to propell it at a given speed.  This is why modern cargo ships are so large, the fuel requirement does not double for each doubling of cargo carrying capacity.  So larger ships potentially make much more money for their owners.

Think of a car at very high speed.  For a given engine output power the wind resistance effects the speed much more than the weight of the car.  A similar thing happens to the hull of a ship but because water is much much denser than air, it all happens at much lower speeds.
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by viciouspenguin » Tue Mar 06, 2012 6:01 pm
gjs said:


viciouspenguin said:


weight is a concern because i will have limited power to push it around with.


This isn't really the way a ship works.  The power required to push it forward in the water is not directly related to it's weight but the hydro dynamic properties of it's hull e.g. you can make the hull twice as long, which will carry twice as much weight, but will not require twice the power to propell it at a given speed.  This is why modern cargo ships are so large, the fuel requirement does not double for each doubling of cargo carrying capacity.  So larger ships potentially make much more money for their owners.

Think of a car at very high speed.  For a given engine output power the wind resistance effects the speed much more than the weight of the car.  A similar thing happens to the hull of a ship but because water is much much denser than air, it all happens at much lower speeds.



economy of scale, i know what you mean, i was generalising. i dont want to have to move unnecessary weight around. it still puts a load onto the propulsion system, which can adversly effect manuverability, and possibily retire the motors before their time.

i'm no hull designer, and thats one of the things on the todo list.....
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by gjs » Tue Mar 06, 2012 8:02 pm
viciouspenguin said:



i'm no hull designer, and thats one of the things on the todo list…..



You have considered one of the major design decisions though; catamaran or mono hull.  The first on the basis that it won't capsize and the second on the basis of a self righting design.  It will be tricky to decide.

I have spent time at sea and one thing I can tell you is that the open ocean is a vicious bitch that smashes everything.  Check out the fate of wave power machines.  If you really want this to operate autonomously at sea for any period of time I would make survivability the top priority.
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by wrhii » Tue Mar 06, 2012 9:55 pm
I seem to recall (though no idea where, and can't look it up at the moment) that some "research vessels" in the deep sea were designed to "self propel" via a dive/rise method.  Obviously, this removes any concern about capsizing if you know it will be diving periodically.  But, does present other challenges.

This could be helpful for propulsion depending on what was required.
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by Gert van Loo » Tue Mar 06, 2012 10:37 pm
I would like to point out at this point that we tested the BCM2835 under many conditions, but the maximum air pressure it can withstand was not one of them.
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by viciouspenguin » Tue Mar 06, 2012 10:39 pm
wrhii said:


I seem to recall (though no idea where, and can't look it up at the moment) that some "research vessels" in the deep sea were designed to "self propel" via a dive/rise method.  Obviously, this removes any concern about capsizing if you know it will be diving periodically.  But, does present other challenges.

This could be helpful for propulsion depending on what was required.



one called the wave glider is mentioned earlier in this thread. its tethered to its wings underneath. unless the tether is broken it is highly unlikley it will capsize.

i think the best solution to capsizing is to stay away from expected storms, bad times of year and sea monsters.

a forum for discussion relating to the FishPi is located at http://fishpi.org/forum/

at the moment its just me talking to myself, but hopefully things will get busier in the coming weeks & months.
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by PaulTech » Wed Mar 07, 2012 12:45 am
viciouspenguin said:


i found an autonomous submersible, not quite as long range but intetesting enough. they popped up while searching for a usb compass.

ocean server"s IVER2 http://www.iver-auv.com

And they start at a reasonable $50K for the basic config :)
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by st599 » Wed Mar 07, 2012 11:04 am
What sort of distances are you thinking about?  Across the bay, the navigation is relatively easy.  Across the Atlantic, you'll probably need o work out Great Circles and such.

Either way, you'll need a PID controller to maintain COG and SOG.  Will you need knowledge of currents/tides on board?

Will you be using some sort of Particle Filter to estimate your position?  You then only need to switch on the GPS intermittently.
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by viciouspenguin » Wed Mar 07, 2012 11:34 am
the atlantic is my ultimate goal, but to start with, and for the proof of concept a lake will do it, then open seas, maybe the channel. anyway that a way off yet.

navigation, i suppose a gps reading could be taken ever hour to set a heading. that would help conserve power for the propulsion system.

great circles? outside of my current knowledge, im guessing it has something to do with the curvature of the earth and bearings to port etc?

tides and currents, certainly currents as there will be periods of low light and dark where the craft will not be under propulsion. some thought will be needed there......
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by st599 » Wed Mar 07, 2012 12:10 pm
http://www.gcmap.com/mapui?P=JFK-LHR

You'll see that the shortest route is not a straight line and requires a course change every X days/hours.
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by viciouspenguin » Wed Mar 07, 2012 12:41 pm
http://www.gcmap.com/mapui?P=JFK-LHR

You"ll see that the shortest route is not a straight line and requires a course change every X days/hours.

so hourly course adjustments using the gps would be good enough.

ive just looked up the gulf stream drift, averages out at 5.6mph. i can see that will hamper things a bit....
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by wrhii » Wed Mar 07, 2012 12:59 pm
viciouspenguin said:


i think the best solution to capsizing is to stay away from expected storms, bad times of year and sea monsters.


Is there a database of the seasonal migration patterns for sea monsters, possibly that includes known breeding grounds?
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