A Student Research Project

Community Projects
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Hi,
Most of this information is available in some other posts, but it was suggested that I create a project in this section, and so I’m duplicating some of that information here in an effort to centralize that information in one place.

As a bit of foundation…I volunteer in the physics department at a small local university outside of Chicago, IL. Outside of my volunteering, I’d read that no one had visited the bottom of Lake Michigan since 1984. While I didn’t plan on visiting myself, I thought it might be a fun project to build a small remotely operated or autonomous submersible that could reach the bottom. And then, the physics department thought that this might be an interesting project for student research, possibly connected with our mechatronics curriculum. And so, here we are.

So, the project itself…

We are in the planning stages of our project, and hope to start work relatively soon. We hope to build a number of small submersibles, each designed to provide hands on experience in areas including design, fabrication, navigation, motion, and instrumentation, all being done at increasing depth, all the way down to the bottom of Lake Michigan at 985 ft. I had previously looked into the good work done on OpenROV, and more recently came across the work going on with Bristlemouth, and thought that there might be a way to include the concepts in these efforts into our own work, whether that might be standardized instrumentation footprints, standardized connectors, and so on. So, perhaps, a great educational experience for our students, and also perhaps, a way to help out a bit with the work going on with Bristlemouth.

That’s the concept. I’ll provide more information on where we’re headed as we get that all written down on paper. You can find details on some ideas we’ve discussed in other threads. I’ll try to get those moved over here as well.

Thanks for your time.
Ron

1 Like
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@estackpole @cradix So, I had an idea that I’ve been noodling about in my head, and thought I’d put it down here.

We have this basic idea about standardizing components for ROVs, whether that be connectors or “parts”, or what have you. 2 thoughts I’m trying to connect…

In an earlier life, I used to manage a datacenter and there were times when we would build new server racks. The racks are standardized, having a known width and depth. There is a standardized height that is referred to as a “u”, so a server component would be that standard width and depth, and then be some height, like “1u” or “2u”, etc. There was software that you could use that configure a rack where you just pick the components and the software tells you the best way to fit them, or if they will all fit.

Most of the plans I’ve seen so far for building basic ROVs involve some sort of rectangular box, usually made of PVC pipe or something like that (depending how deep we’re trying to go). That’s the path that we are mostly likely to go down with our own projects. And so I thought that one approach would be to take the server rack configuration idea and use that here. Make the “box” for the ROV a standard size, or have that standard “box” within the frame somewhere and then come up with a standard size for the components to fit into it. Let’s make up an example.

Let’s say that you make a box that is 3’ x 3’ x 3’. (the numbers are totally made up just for sake of discussion). And let’s say that the standard unit of measure for the components is 1 cubic foot, so 1x1x1. Let’s call that “1R” just for fun. You could fit 27 of them into the box. Let’s say, further, that you create a backplane on the box that has Bristlemouth connecters built into it, the idea being that if your component was configured some ways, it could slide in and plug into the backplane (you could just as easily have Bristlemouth cables back there, too). If you create a component that is, say 1R wide and 3R deep, it would fill one “column” in the box, and plug into the backplane. If it was 3R wide and 3R deep, same thing. It could just plug into the backplane. You could potentially have the max of 27 components if you had some standards that allowed for passthru connectors to be built into each component. Or you could have something like an “L” shaped component that might block access to the backplane to components in front of it, but if you had a passthru connector standard, one component could plug into another component to access the backplane. Then you could have software that could take a list of components, and configure them into a space, sort of like playing 3 dimensional Tetris. You could, then, have really simple configurations, or really complex configurations, depending on the number of spots available in the 3D grid, which could be of varying size depending on the size of the ROV.

Now, back in the land of student reality, we could mimic some of this by using standard sized project boxes for each component (or cylinders or spheres depending the depth requirements), and just stack them different ways within the ROV frame. A 3-across grid could have a camera box in the middle with 1 light box on either side, for example. And we’d just be using cables in our first ROV(s). I don’t know if the Bristlemouth connecter can be configured the way I’m thinking, so it’s all just brainstorming right now. I have to take a closer look at the current specs to see what it can do. At the very least, it would allow us to easily move components from one ROV to another because they’re all standard size, which mean that the ROV could be built with connector and brackets in standard locations. That could apply to thrusters, power supplies, control units, etc etc etc. Or this could be for instrumentation only, with everything else being customized for the particular ROV. You get the idea.

That’s the idea. Sorry, I should have drawn some diagrams to make this all clearer. For right now, I was more interested in getting it written down to see if any of it made any sense.

Ron

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@Rongee I’m definitely with you about having an easy way to sort of “drop in” physical parts to a frame, and I think I understand the concept you’re describing. Since so many of the designs I’ve made have specific positioning requirements for the various sensors, thrusters, etc, I’ve had to do a lot of thinking about what level of mounting standardization versus freedom makes the most sense. As we discuss and the other thread, what I arrived to was just a simple hole pattern that everything could be mounted with rather than requiring a specific volume to be occupied by each system kind of like server racks do. That being said, it seems like your idea might work well and some other types of scenarios.

As we’ve been developing Bristolmouth modules for the Sofar Ocean Smart Morning system we’ve kind of automatically arrived at some standard geometries so that parts are interchangeable. It definitely seems like designs converge on some typical set of dimensions whether it’s intentional or not.

I wonder what the ideal dimensions would be for one of these modules like you describe…

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Hi @Rongee

I really like the idea of a standard configuration - that will allow the students to consider the “classic” models and sensor configurations for underwater ROV’s. One consideration re: spacing should be either a) the ability to easily transport the assembled ROV or b) the ability to reliability re-assemble the ROV without the need for onerous re-calibration.

Cathy

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@estackpole I see that @ronhgee had suggested a cubic foot. I’d maybe go with a 6" cube.

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Well, just to be clear, I grabbed that number out of the air just to have something to use in the example :slight_smile: For example, the “u” in the rack example I wrote about is actually 1.75". How they came up with that measurement I have no idea. Their main point is that you can use that unit to describe the capacity of a given rack. So you could have “30u” rack that tells you the total vertical space available. How you use that “30u” is up to the designer.

In a 3D space like the interior of a space in an ROV, I could see the standard measurement go either way. You could have a really small standard unit, like 1 cubic inch, that would allow for almost infinite variety of configurations, but it’s far more likely, I think that the reality of existing components sizes would result in a minimum configuration unit that somehow fits those existing dimensions. On the other hand, something like a 1" grid would fit with Eric’s idea of having a predrilled and tapped surface for attaching things. Just brainstorming at this point. It’s important that ideas get tempered with the reality of what is already out there.

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One other thing I’ve been doodling on is the idea of weight distribution to maintain trim. There are a lot of areas where I have no idea what I’m talking about and this is one of them :slight_smile: , but I think that these configurations somehow have to take into consideration keeping the ROV “balanced” within some limits. At least, I think that’s needed.

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@Rongee weight distribution is an issue, but if we go with a standard 1 inch grid, and characterize the moments of inertia for each module before connecting it to the frame - it should be predictable.

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Haha, I think that calculating moments of inertia will be a great thing for students working on the project to do. For old tinkerers like me on the prototypes, I’ll probably go with “that end is low, I need to add some boyancy there or add weight on the opposite side”. Seriously, tho, I agree with that idea and I can imagine a time when a configuration tool might be able to do that “balancing work” automagically. But, until then, there are almost certainly approaches that are already being used in existing ROVs, which is something to be learned more about (at least for me).

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I thought it’d be a good time to provide an update on where our project stands. We’re continuing to build up the outline for the project work and where it might lead. We’re looking at building a series of submersible ROVs, each capable of increasing depth. The early ones make use of existing plans from variety of educational sources, with mostly easy to acquire materials. From there, we’ll move into custom designs with either more depth-capable commercial components or components designed by the students.

We’ve been in contact with a couple of commercial providers, looking for background industrial knowledge as well as potential sources for components. I was able to find the folks who built James Cameron’s Deep Sea Challenger, who in turn put us in contact with other providers. While I’m primarily interested in developing sources of information, Triton Subs has been nice enough to provide us with some leftover pieces of syntactic foam so that our students can get some exposure to the material.

We’re also in contact with local natural resource departments in Illinois and Wisconsin since they have interest in Lake Michigan, from the ecosystem to shipwreck documenting. There may be ways that we can use our ROVs to assist in some aspects of their work. These are in the early stages of developing relationships.

It seems to me that if or when we can get access to some Bristlemouth connectors, we could include those in our testing. While our early ROVs might be duplicative in the testing, our deeper operating subs might provide some valuable information for using the connectors. I don’t know how much testing has been done with the connectors so far. But, maybe we can be of some help.