The device that could save your life?

[Schwob]

I am an engineer. Conceptually there is no difference. You are opening and closing solenoids based on inputs to a control algorithm. The implementation is different but not by much. Sensors provide input to an algorithm that controls valves.
Reaction to a failure of the system also seems similar. Identify an out of control ascent - disconnect the supply and dump the air in the wing. How is this different from an uncontrolled ascent in any diving? How is this different that your reaction to a stuck O2 solenoid?
The major difference is really in the purpose. We are discussing an emergency device not an autopilot BC. If you become unresponsive at depth what are your options? Drowning if no action is taken. A less than perfect device that would get you moving to the surface doesn’t seem like a horrible alternative. Yes it could fail. If you’re conscious you react. If not it’s a matter of whether or not you are better off at depth or on your way to the surface.
I don’t dive an eCCR and I’m not arguing for this device either. But if someone can justify accepting the failure risk of one it is not much of a leap to accepting the other.
I’ll stick to OC diving.

I concur. No major difference. A detail difference might be that a better than dumb "auto BCD" (just for life saving or for full Auto? ... let's just shelf that thought for the moment) might want to be programmed such that it learns and updates the system latency and hysteresis each dive so as to respond and time solenoid times correctly for different divers, different suits, no suits, old stiff neoprene, soft squishy, thick, thin, dry w/oinsulation and Michelin Man...
But that is entirely doable by designing the SW right and cognitive of what matters to make the call. A DC with pressure transducer should suffice for input... a very, very, very reliable one and maybe with back up... Power must be infallible too... etc...

It may get trickier in SW and verification of it's robustness with down currents etc. but still should be quite manageable

Wether the thing would be used in some sort of diver enters next target depth mode kind of "let the BCD do it" way plus - or just in some kind of "no diver response in such an amount of time default to safe ascend from dive at this point" mode is almost irrelevant for engineering it. The big problem in making sense of it is to figure out a truly fail safe trigger for this sort of auto unresponsive diver ascend mode. A timer is (diver did not respond in such and such a time) would not work well with distracted divers (photographers, task loaded but OK, seing the sight of a life time...). A great and reliable input of the diver's pertinent biomedical signals might make more sense. That's where it would get tricky...

A simple "oh **** failsafe button to push" (lift cap, push button) is easy and if the ascend profile is safe (very doable) also truly safe, except it requires the diver to be able to do that... and of course a safe ascend, pending on where from in the dive can be quite slow... and may not be the best ascend to try to safe a life, pending on what the situation is (i.e. no gas being drawn in the past minute might indicate that a 6 minute ascend might not help much...) No final conclusion here, except to say that how to trigger and based on what inputs is the tricky part, the "Auto BCD regulating" part itself less so.

Edit: All that said, I am happy fine and content with cruising solo in full manual mode... And I'de be highly unlikly to trust software to not shoot me into an embolism unless... Most SW is written these days in the "write it and fix bugs later" mode and endless bugfixes are the result. The fact that smartly purpose built well pre-planned SW can indeed be bugfree and that the SW architecture can indeed foresee all it needs to foresee (on a limited overseeable scope, which this is) is thought to be an impossibility these days. I would not want to dive such a device if engineered any other way than the "it has to be bugfree and fail safe" way. I realize I am more than a bit odd in seeing that as entirely achievable... and if such a device is engineered by people who do not think that achievable and hence do not even try in earnest ... then it's not for me...
(Bugs must be kept out by design. Finding them in the "end inspection" works as badly for SW as for other industries, but it has become the mode SW seems to be made).

 

[doctormike]

A simple "oh **** failsafe button to push" (lift cap, push button) is easy and if the ascend profile is safe (very doable) also truly safe, except it requires the diver to be able to do that... and of course a safe ascend, pending on where from in the dive can be quite slow...

I'm confused. What device are you suggesting? Is this to get an unresponsive diver to the surface? Then that's a big difference from an auto-BC. The difference is that an auto-BC needs to add and vent gas to maintain neutral buoyancy, while the "parachute" for the unresponsive diver doesn't need to vent apart from the automatic overpressure valve to keep the bladder from exploding. It just needs to blow them to the surface, ASAP.

What would be the scenario where you would want to do a "safe ascent" for an unconscious diver? And if they aren't unconscious, why wouldn't they just do a normal ascent with a normal BC?

 

[Schwob]

What would be the scenario where you would want to do a "safe ascent" for an unconscious diver?

Fair question. That's why I say it's the tricky part.
Venting: Of course venting is needed - well, OK, that was my thought ...unless you would truly want to have a fully fledged fully runaway ascend as your failsafe. It may have been proposed, but that could be awfully, awfully fast. I concede that I have no idea if there is such a thing as a more controlled emergency ascend speed that is faster then a regular ascend but helpfully less disasterous than a fully runaway ascend. I presumed there could be and if the device can control inflation and venting, then whatever profile is wanted (found out to be the best benefit to damage compromise) could be used for such an ascend. I concede that I may be somewhat competent on the engineering end of things, but not so much on the physiological end of things.
If fully runaway ascend is wanted sure just inflate. Personally, I would not want any such auto device on me.

 

[doctormike]

Fair question. That's why I say it's the tricky part.
Venting: Of course venting is needed - well, OK, that was my thought ...unless you would truly want to have a fully fledged fully runaway ascend as your failsafe. It may have been proposed, but that could be awfully, awfully fast. I concede that I have no idea if there is such a thing as a more controlled emergency ascend speed that is faster then a regular ascend but helpfully less disasterous than a fully runaway ascend. I presumed there could be and if the device can control inflation and venting, then whatever profile is wanted (found out to be the best benefit to damage compromise) could be used for such an ascend. I concede that I may be somewhat competent on the engineering end of things, but not so much on the physiological end of things.
If fully runaway ascend is wanted sure just inflate. Personally, I would not want any such auto device on me.

Again, what is the scenario that you are assuming that this device would be used for? Unconscious diver? Or something else?

 

[Schwob]

Again, what is the scenario that you are assuming that this device would be used for? Unconscious diver? Or something else?

Mike, trying to answer your questions here, then I need to be off the air for a few hours...
I am assuming unconcious diver.
I am saying that the full BCD control part for any desired ascend profile (for sone sort of controlled ascend) is the comparatively easy part and would if anyone so desired also allow other sorts of auto mode (I do personally not desire such).

I am also saying that the trigger part that never triggers when it should not, but always does when it should is the truly hard part.

I am assuming (and may be incorrect in that assumption, I certainly am not a doctor) that auto initiated full fledged runaway ascend is likly not desired and that I absolutely would not want a device that can initiate that on me.

I have no idea if there is testing that would provide knowledge for anything like a good compromise emergency ascend speed (obviously there won't be testing for such for an unconcious diver). If there were not to be a better speed than full speed, my whole point on more control is week. I assume, but do not know, there might be a better compromise.

Does that answer your question?
Is it OK with you that I offered my opinion on the BCD control part in reply to the post I replied to ?

 

[doctormike]

I am assuming (and may be incorrect in that assumption, I certainly am not a doctor) that auto initiated full fledged runaway ascend is likly not desired and that I absolutely would not want a device that can initiate that on me.

I'm a doctor. If you are unconscious and alone underwater, the only remote chance of survival would be a rapid ("runaway") ascent, as fast as physics allows. There is no scenario where it would be better to delay the surfacing of an unconscious diver because of decompression issues.

This is different from the rescue of an unconscious diver, where the rescuer has to consider his or her own safety, and has the ability to maintain an open airway and possibly a gas source for the victim. But that's not what we are talking about.

Now you might not want such a device because of a concern that it would go off when you are NOT unconscious - I wouldn't want it either. But if you are talking about designing a device to surface an unconscious diver, then you wouldn't design it to slow the ascent.

Is it OK with you that I offered my opinion on the BCD control part in reply to the post I replied to ?

I'm not sure what you mean by this question. This is a discussion forum, where we talk about diving. I thought that was what were were doing. Are you asking me if it's OK because you think that I have said something inappropriate?

 

[Schwob]

I'm not sure what you mean by this question. This is a discussion forum, where we talk about diving. I thought that was what were were doing. Are you asking me if it's OK because you think that I have said something inappropriate?

Inappropriate?

No, certainly not. We're good. We are just not really talking about the exact same thing - and that's ok.

I stated (somewhat lengthy) what I thought and why so in my first post in reply to @Diver-Drex . I clearly was not talking about an ascend as fast as possible device. Not my cup of tea. I made that clear to.

You had questions about that, I replied. It looked to me like it should be clear.
I may have taken your re-questioning, starting with "Again, what is the scenario..." differently from how I meant it.

I do realize now that the fast ascend device is the one you are talking about exclusively. That's fine.
I also understand now that you, as a doctor, state that a fastest ascend is the only way to have any hope for an unconcious diver underwater and better than any slower ascend. That was not clear to me prior. Thanks for explaining and clarifying.

I am just not really talking about an auto-uncontrolled-ascend-device. I was stating I don't care for it and was stipulating another approach. You clarified that in your medical opinion such an approach would be worse than fastest ascend. I got that now.

So far so good.

Since I still don't care for such a device let me further clarify that I am stipulating that (me personally) if I were to wear any such device (not likely) that I might prefer a more measured device that allows for a more measured response - e.g. say I suspect a heart attack in progress or some other severe medical event... but I am not out just yet, but feel I will be to incapacitated very soon to terminate the dive myself... Maybe a device with three modes:

A: controlled regular speed auto ascend (see below)

B: Some faster, but less damaging emergency ascend in specific cases (detected by system (see below))

C: maybe the full speed ascend
as well if certain conditions are fulfilled. Maybe like this:

A: When a safe against accidental actuation emergency button is pushed, continuously held and withdrawal of gas (or breathing more directly) is detected at least every so often.

B: That button is pushed but at some point not held and also auto ascend was not cancelled, but breathing or gas withdrawal is (in some form) detected.

C: No button was pushed, breathing or gas withdrawal is not detected for an appropriate period of time and after warning beeps, lights and whatnot.

And I would disable "C" because I wonder how likely it is of me going out w/o warning compared to say a flaw in the sensing system / communication that would trigger a false "alarm"...
This mode would eject me to the surface either after I am dead already, or if not yet would deliver me there with minimal successful rescue chance afterwards.
Why would I want to expose myself to an uncontrolled ascend if it could be triggered by some system flaw? Even so I do not know which is more likely I personally do not want that exposure and would prefer modes A and maybe B, but really, I would just keep it simple and not go that route at all.

But if some one were so inclined, how sure are you that triggering such a mode with a more measured response along A and B (with "C" in there say only if you opt in) would not deliver statistically better results - maybe simply for the most part because it offers a potentially less damaging auto abort prior unconcioness?

I do not know the odds - I am not making a statement about them - I am just saying how I would be inclined.

 

[АлександрД]

I`v published information about such device as separate topic, may be in the future I will add some more translations there

Briefly:
1969 year! In the magazine Спортсмен-Подводник was described construction of fully mechanical device, that allow inflate something (west, boui, collar), and allow to the unconscious diver rich the surface.
Fogotten pages of Soviet dive magazines - here is translation of that topic.

So - now need to find company, who can produce additional device, connected between 1st and 2nd stages of regulator, and connected to BCD, very simple, and allowed unconsicous diver reach surface in any cases.

 

[doctormike]

Inappropriate?

No, certainly not. We're good. We are just not really talking about the exact same thing - and that's ok.

OK, great! Wasn't sure if you thought that I was being snarky or rude, and I really didn't mean that. A problem with conversation over the internet without social cues...

Dive safe!

 

[Schwob]

A problem with conversation over the internet without social cues...

Very true...