Where can we go?


#1

It's hard to comprehend the depth and vastness of the ocean. It's also hard to comprehend how deep 100m is (which is how deep the OpenROV can go).

Our pal Brian Sullivan from the Google Oceans team has made this amazing graphic using the Google Earth Engine, showing exactly how much of the world's oceans are less than 100m deep:

https://mapsengine.google.com/05499511170989622376-16445443737533383358-4/mapview/

Two things this made me realize:
1) We've got a lot of great exploring to do with the OpenROV.
2) We need to build one to go even deeper.

Cheaper and deeper!


#2

Is the limitation due to signal loss over the cable on lenghts over 100m, or becouse of the rov/pressure?


#3

Pressure.


#4

Ok, well that sounds nice. the open rov project for me is essentially the electronics configuration, which give people the oportunity to build a rov that can go even deeper than 100m.


#5

Since u have a "shell only" kit in the store I think u should ad a "electronics only" kit!


#6

Joel,
That's awesome! Excited to see your design!
That's a good point - we figured we'd offer the parts that we produce, like the controller board and IMU board, and then the rest of the electronics you could source yourself.

Keep us posted!


#7

Hi Joel, one of many project ideas is to incorporate the core or brain, if you will, of the ROV on to deeper platforms, even quite different ones, where the controller could be as plug-n-play on a benthic rover as it is on the ROV kit, as it could be on an AUV. It's possibly a fundamental necessity for this budding community of marine explorers.


#8

In NASA we had a saying when they came out with "faster, better, cheaper" which was "pick two." While I'm afraid the answer to "cheaper and deeper" may be to pick one, I do look forward to the challenge.


#9

Hi friends:

I've been playing with some numbers and parts from the same stores as there from the original OpenROV matherial list.

Deeper means stronger, and improving the wiring passthrough.

Togheder with those numbers I've check for the less required changes to the original 100m ROV.

My results say that a simple framing and minor changes, could improve actual ROV operating depth to 157 meters (n=0.8).

Going beyond this requires changing both end caps design and building. Caps modification, cylinder change and internal framing, working togheder, could achive, from my numbers around 400 meters depth with no significative price increase (More optimistic numbers reach over 700m depth).

Passing wires from inside to outside the main cylinder could be done by coper wire hot-clinching, with an external tile for reinforcement and watertightness.

Electronics is no my thing, but this ... IS.

Regards


#10

700m...wicked! that's ~2297 ft! Mesopelagic zone here we come!


#11

Looks like we’re going to have to knock our heads together for an Open TMS cage for the MK3 Open ROV! got a few ideas already in my head for such a project :slight_smile:


#12

Those are the datas I'm using. Please correct me if they are not OK.

Mat: Cast Acrylic (PMMA)

Units (IS -- > meter, Newton, derived unit Pascal= N/m²)

Young Mod: 2800000000 Pa
Ult tens str 69000000 Pa
Shear str 62000000 Pa
Comp str 117500000 Pa
Poisson rat 0.35

We can surely increase working depth.


#13

in the depth test, my openROV descended safely to 230m with very simple changes and with only a small increase in cost.

OpenROV can currently communicate to just under 300m as is. which is awesome!


#14

Great, Darcy.

Good results. Glad to know my calculations fit your results, albeit Im more "conservative" as mine are not real tests.

Im using a safety factor of 0.8 as per ABS rules.

About end caps...

The goal is achieving a pressure between disks gaskets and tube, bigger than hydrostatic pressure. A reasonable factor would be 0.8 (1.25 times bigger).

The problem is that as depth increases, tube buckling increases as well. Distortion leads to a reaction at the inner disk, wich will be the only one working as a support, making effective pressure on the gasket to decrease.


At the same time, all radial pressure is transferred to only one of the disks, the inner one, which own buckling is increased, by the way could achieve an overload situation.

As it can be seen at the pic above, a collateral effect, is that effective force on the gaskets and disks, starts to have a significative axial component (F'), and then .....

- Force is no more "normal" to disks and gaskets. Arrangement efficiency decreases (Is a cuadratical and not a linear function of hydrostatic pressure)

- Reaction force + Pressure -----> Disks distortion increases.

For depth range improvement:

A new design of "End Caps" is required. That design, would have to work against the E Tube distortion. May be by an external ring with its own gaskets working from outside.

A way to limit the E Tube distortion is also a requirement. This, from my point of view can be achieved by a thicker wall, or by a "wise" internal framing.

Finnally as we say here "There always exists a Technical indetermination, but never an echonomical one" or ... waht is the same "Among all thechnical solutions, the cheaper is the better"

Regards