life support

How feasible is this idea?

So I'm in the process of building a two person under water sub capable of depths of 500 feet under water safely, 700 max.
two main features of the sub i'm having design problems with. the life support system being one...and the eva suit being a nother. I'm wondering if the capability of the "Arduino Extreme" would be able to handle this task. It will have to be able to transmit to a small screen and have a menu that has the options to manually control things like inside lighting, Co2 scrubbers, inside pressure, and inside heat/antifog for windows. that stuff...and if possible communicate with an eva suit via raido to display things on a screen that the eva user can see...simple messages like come back or running low on oxygen or stuff like that.

also how hard is it to transmit photos over raido from two "Arduino Extreme" boards? with extra memories and the right sensors and what not would you say this is possible/feasible? any suggestions or ideas?

Is this a piss-take or do you work for a multi-national company?

And what is an "Arduino Extreme"?


the Arduino Extreme is a type of Arduino board. and This isn't international. though I don't know why that would matter?

I would think you'd want that stuff all soldered together, not rely on plugged together headers on a stack of shields. SMA type connectors for radio antenna connectors to feed thru the sub shell, etc.

Do you have a link to "Arduino Extreme"?

Arduino Extreme is a much older version by

Arduino could do what you are suggesting, except radio is not good for salt water communication. Research what divers are using now.

If you are diving, you have money. Don't use Arduino. Buy thoroughly developed and tested stuff.

If you are developing for diving, you have money, and can buy medical/automotive grade components that have a significantly higher life expectancy and lower failure rate.

I would not have your life depending on Arduino. I am not trying to put Arduino down, but I do not want my life depending on arduino, as you need for it not to fail. Ever. I'm sure Atmel would agree with me. They may however sell such devices, but they aren't used in Arduino Products.

This isn't international. though I don't know why that would matter?

Atmel AVRs (such as the one used in Arduino) are not legally approved for life-support applications, so don't try to sell your device.

If I were doing this as a hobbyist, I'd think long and hard about risking my life with my own programming skills. If I decided to go ahead and risk it, I'd definitely design a fully redundant (no single points of failure) system with plenty of failsafes. In fact I'd probably go to a triple-redundant system with voting (don't alter the CO2 scrubber state unless two of three Arduinos, each with their own independant CO2 sensors, agree it needs to change). Even then, I would seriously consider just using the Arduinos to sense things and recommend actions to a human so the Arduinos did not have full authority to kill me.

If I really did want to give the Arduinos authority over systems, there would for sure be a nice big red manual override to take the Arduinos completely out of the circuit and go to full manual control of all systems.

Radio waves can penetrate a short distance into water, but don't count on getting much range or bandwidth. Certainly not enough bandwidth for photos.

Photos are generally beyond the abilities of the Arduino. You can transfer JPEGs but don't expect them to be high-resolution and do expect transfers to be slow. Don't expect to do any image processing. A Raspberry Pi is far more suited to dealing with photos.

An "eva" suit suggests the presence of an air-lock or a moon pool.
A moon pool suggests saturation diving, and an air-lock suggests big engineering and added bulk, so in either case I'm assuming you've got serious amounts of money.
How can I help?

[...]you've got serious amounts of money.
How can I help?

This is easily the funniest thing I've read all day.

Anyway, 500 ft, that's what, 150 m in real units? That's pretty deep if things go south and you need to surface.
With double or triple redundant circuit doing the hard work, another independent one or two just to monitor the situation and some good old fashion analogue instruments I think I'd be bold enough to take the sub for a spin.
But that brings me to that old saying: A man with a watch always knows what time it is. A man with two watches is never quite sure.

DIY EVA suit... Kerbal Space Program comes to mind.

Anyway, 500 ft, that's what, 150 m in real units?

Feet are imaginary? Obsolete and annoying, perhaps...

That's pretty deep if things go south and you need to surface.

Most P-Subs incorporate external drop weights so that surfacing is still possible even after a total power failure and the loss or blockage of all compressed air. A positively buoyant locator beacon can also be released from the top of the hull if the drop weights don't do the job.

Hopefully, the drop weight and locator beacon releases are good ol' fashioned levers and not under the control of the Arduino...

isn't international. though I don't know why that would matter?

It doesn't, I was referring to the fact that I don't see how such a job can be done in a garage with 2 Arduinos and a some 44-gallon drums, it would need the backing of a huge company and serious engineering resources.

OK maybe it can be done in a garage, it's not my field, but it seems to me that you would have to have a death wish to do it.

One thing is for sure, you do not want an Arduino in control of any critical function without double or triple redundancy, but even then it's just not the right platform I think and how good are your programming skills? Good enough to bet your life on? Even if they are do you trust the Arduino libraries?

BTW My programming skills are good enough, good enough to bet your life on that is :slight_smile:


Im assuming the sub is at 1 atm? So your project is to build the control for that and to create a o2/co2 control system.... and to build an eva suit that goes in and out to 150m of water (~16 bar delta p). So your eva suit is also 1 atm (akin to a newt suit).

The budget for that is massive. Of course, if you're not making the eva suit 1atm, you can instead deal with the decompression schedule in the 'airlock'.

As for comms, presumably you're diving tethered, so why not use a cabled connection? If you're free swimming, go for sonic comms.

It does all sound a bit fairy tale :slight_smile:

Most people doing anything 'real' in this space tend to prefer simple manual controls/overrides, for WHEN it goes wrong.

Anyway, that aside, I'd love to see some pictures of the sub itself!

how hard is it to transmit photos over raido

Under water? Impossible.