All right, everybody.
Don't feel shy.
If you want, you can move up front.
Yeah, you over there.
Let's move up front.
Anyway, this is 10,000 yen into the sea.
This is Flipper.
Let's give him a big hand and say something like, whoo!
Come on!
Awesome.
Hello.
So, as he said, I'm Flipper.
This is my talk, 10,000 yen into the sea.
Essentially, well, I mean, just to start with,
can I get a show of hands?
Who enjoys filling up their gas tank?
Yeah, I'm not a big fan of it either.
Actually, I spent four years commuting to and from my community college,
four years, two-year program.
I had other things to do.
So it was a 45-minute drive each way,
so I pretty much ended up putting about as much money into my tank
as I saved by living in my parents' basement.
So all the benefits of living in my parents' basement with none of the cost savings.
So that was kind of an interesting experience.
And the reason why this is relevant is, shortly after college, I saw underwater gliders and
they kind of blew me away because when you see the typical range and duration of these
things missions, it's pretty incredible.
Around 3,000 kilometers on a single battery pack charge.
Yeah.
And I work with electric vehicles professionally,
partially as a consequence of this project.
And I got to say, if you can show me a Nissan Leaf that can go 3,000 kilometers,
I'll be pretty impressed.
One of my coworkers says it's all about the drive cycle.
So as I said, I'm Flipper, and this is kind of what I do, electric vehicles.
And additionally, we have nyt
professional 말ed cram vehicles here underwater.
I keep on trying to talk my boss, and to let me turn one of our vehicles into a submarine,
Marine, but so far no such luck.
So I'm finished with my education and not much in the way of job options at the time,
kind of dead end jobs and I'm killing time in the bathroom because I didn't really like
my job.
Reading the Oregonian and I see an article on Oregon State University's underwater glider
program.
They were talking about how they work, they show a little cutaway diagram and I'm kind
of blown away.
It's all like, wait, wait, wait, how much do these cost?
I could do that, you know, $100 tops.
So that's where the 10,000 yen comes from is at one point in history that was about
$100.
A little bit of Jules Verne's too.
So in order to build an underwater glider for $100, you kind of have to be an expert.
An engineer or hacker, one of the two.
I definitely wasn't an engineer, so I guess that's why I'm here at DEF CON with you guys.
So how do you design an underwater glider?
You have to learn how to design an underwater glider so it was really the start of education,
self-taught in design and manufacture of underwater vehicles.
So...
AR.
studying machine tool technology at the time, manufacturing engineering type
stuff, eventually got a transfer degree and so yeah it was a great vehicle to
actually learn and gave a really good incentive to you know study STEM subject
matter and ultimately transitioned into an interest in an engineering transfer
degree. So what is an underwater glider? Normal underwater vehicles propel
themselves through the water using a propeller. Pretty straightforward.
There's no propeller on an underwater glider generally speaking. They use
something similar to a fish's swim bladder to change buoyancy in the water
and as they float to the surface they have wings on them. Does this thing work?
So wings. And those actually help transfer the change in altitude into
forward movement and so the efficiency of the vehicle is going to be determined
by a couple things. First of all the efficiency of your fish bladder buoyancy
engine. Your drag. Big factor is your drag and then also kind of related to drag is
your glide ratio. How many feet forward you move through the water for every
foot you lose or gain in altitude. One interesting thing of underwater
vehicles is they spend about half the time
flying upside down.
Because you know your gravity vector flips its head when you are going
against the water column or going down with it. So yeah they're autonomous
underwater vehicles that can travel long distances on battery power. So history
you know it all started back in you know 80s or something. I wasn't even born
yet so it doesn't really matter. Very egocentric view of the universe.
And there's a few Florida
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people out in boats at $40,000 a day. But the problem is we can't actually control where
they go. They're kind of like hot air balloons. So it was like what if we strap wings on them?
And underwater gliders were born. Henry Stommel was one of the people who wrote some kind
of pioneering articles on the potential applications of these things. And what you see before you
today between the Scarlet Knight, the Slocum, the Spray, it's become a very popular vehicle
class simply because of the range you can cover for the amount of energy you have to
store. So the Scarlet Knight is one of the record holders. It was put together by Rutgers
University and it was essentially a Slocum glider that had been loaded down with extra
battery mass and stretched out a little bit. It uses lithium CSC cells. It's a very
impressive because the high test peroxide rocket fuel you see in the movie Moonraker
as far as I can tell actually has lower energy density. So those are pretty impressive batteries
although also fairly expensive. That's not what I ended up using.
So I don't know if this is the correct way to design an underwater glider. But after
going through, you know, 10, 20 designs in my head before even trying to build the first
draft.
This is kind of what I settled on as the proper procedure. Maybe somebody can correct
me if I'm wrong. But you don't really know how you can package your components until
you know what your components are. And buoyancy engine being one of the key elements is going
to determine the efficiency. You really have to start with that. Energy storage system
is going to be dictated by the energy requirements of your buoyancy and then, you know, whole
design. It's a pretty straightforward process. Very few moving parts.
So eventually I did, you know, I'm not a very decisive person, but eventually I did
come to a conclusion on how I wanted to build one of these things. And that was with a phase
change material. There's another vehicle out there that uses PCMs to propel itself
through the water. It's called the Slocum thermal. And I'm not doing that because it
looked really expensive. I read some NASA tech briefs. And they said, you know, it's
kind of talking about the concept. And I think it was like n penta decane was the alkane
they used. And really expensive per ounce. It wasn't really on the table. Because my
goal going into this was, remember, I said I could do this for $100. If I'm spending,
you know, $200 on my phase change material, I'm kind of already blown out.
So these were the design requirements I went into it with. I wanted the, you know, barriers
to entry to be super low. Because even though I had access to a milling machine and a lathe,
not everybody does. So I wanted, you know, all of you to be able to take your DEF CON
CD, take the solid models that are on there, and go home and build one of these yourself.
And then, you know, range of efficiency. You're not going to take a two order of magnitude
reduction in cost without, you know, taking some hits on range, efficiency, performance.
So it was kind of a best effort basis. I'm pretty optimistic. I've got a fairly large
battery pack. I've got a fairly large battery pack. I've got a fairly large battery pack.
Compared to the currency, or compared to the current consumption I'm looking at. So
we'll see. Here's one of the earlier efforts I made
into actually trying to design for manufacture. That's a Harbor Freight air compressor gear
being used to index several syringes. And this design actually served as a little bit
of inspiration for a hack I had to make towards the end of this project.
Overall, the check valves involved were kind of a prohibitive feature that just disillusioned
me with this concept. So I considered a lot of things. I struck out electric motors, linear
actuators pretty early on in the process because, you know, at the time, lathe and
milling machine were pretty much, you know, a requirement to make those happen. The weight
of using an off the shelf linear actuator was pretty massive. You'd end up with like
a scuba tank pressure housing and that's no fun. So, you know, it's a little bit of a
challenge. So wave and solar power, interesting concepts. I'd like to explore them a little
bit, especially for one concept I might mention at the end. But overall, hydraulic pumps
and phase change materials kind of showed out to me as the best choices available.
So paraffin wax expands 10 percent when it melts-ish. And it's got a very high specific
heat. So when it does melt, it will stay liquid for a very long time. So it's a little bit
of a challenge. So I was looking at using soldering irons as a resistive load to actually
melt the wax. And this is just kind of a breakdown comparison of various energy densities
I was looking at for kind of guiding my decision on how to build the buoyancy engine. And when
I first started on this project, there really wasn't much in the way available of low cost
inertial navigation. You had the multi-we project, which I thought was pretty genius
because they took a nunchuck and a motion plus from a Wii game console. And they actually
made a six degree of freedom IMU out of it. Welcome to the future. This is really cool.
This is a $33 board available from Hobby King. And I can't imagine they have more
than, you know, $5 of profit margin built into that. You get a really cutting edge chip
on there called the MPU 6050 or 6000, one of the two, depending on if it's SPI or ITC.
But the point is, it's got a built-in magnetometer. And so it can do a complete nine-degree wave.
It's got a six degree of freedom sensor fusion, which is the ability to distinguish between
gravity and linear movement through space. And when you're trying to actually integrate
your inertial data, you'll run into problems unless you have some pretty good math background
or a fantastic product like this behind you. That's the 3DR Robotics GPS chip. It was available.
And it's actually buried in the nose cone of my vehicle right now. And it's actually
coated in a nice thick goop of RTV compound. Hole design was kind of fun. I spent most
of the past year working on that as a specific aspect because it ultimately guided the production
of the rest of the vehicle. Once I knew what I was packaging, I had to actually wrap it
up into some sort of fluid dynamic hole form. And so based on the research I had, I'd heard
some interesting things about, you know, 30 to 1 glide ratios with something called a McMaster's
zero foil, which is pretty much a NACA four-digit series 0030. But based on the simulations
I did using a program called Profili2, marketed at RC Plane Design, its main claim to fame
was it didn't stall out at high angles of attack, whereas the black line has one of
the sharpest peaks on there. So NACA 009.
Or 0009 was kind of out of the question too. So kind of middle of the road choice of the
symmetric airfoils that were well understood at the time. Pretty common options are, you
know, NACA 0015-ish. So I think my wing route is NACA 0015 and wing tip is NACA 002. And
what that does is hopefully like the Routon Long Easy, if you end up stalling out, the
wing route stalls before.
The wing tips, and that will cause the pitch to self-correct. Fingers crossed on that. Not
a lot of testing in that regard.
So first concept, I took a polycarbonate tube, a wax motor, used to control a dishwasher
latch, funny enough. High force, high latency, low efficiency, unfortunately, as I found
out later. And, oh, no. I'm not sure if I'd submitted my CFP at this point. I don't know.
But I was kind of sweating at that time because I'm apparently really, really bad at fiberglass.
Who knew? The original idea was that I would be using
hot wire foam cutting techniques to actually generate the whole form and then lay fiberglass
over it. And as you can see from this picture, that wasn't going so hot. So not as easy
as it looked on YouTube. It was not going to hit my deadline at that rate. So throw
money at the problem. I've generally found that when time is of the essence, money can
generally buy you time back. So I bought a 3D printer. I really am happy I made that
decision. 3D printers are really cool. One of the design requirements, being able to
build this thing in my underwear, check. So similar design, same whole form, but now
broken into smaller chunks to help with the print volume and also, you know, trying to
minimize the overhang of the printed parts.
Support material isn't obvious. I don't know. I don't know. I don't know. I don't know.
It's an option. And one of the largest prints on there actually was using support material.
One month turnaround time, you really can't argue with that. And I knew 3D printing could
really help expedite the design process and getting you through multiple iterations. But
until I'd experienced it firsthand, kind of saving my bacon on getting a proof of concept
out the door and second, third revision, whatever, I was incredibly impressed with
the value.
you. That 3D printer I showed was a Delta bot style design and they are one of the coolest
to look at when they are running. Cartesian bots are a little bit lame in my opinion.
And that's the robot you see in front of you. So $100 price target. $31 a kilogram for my
plastic. That could be cheaper but let's try and be generous just to make sure I don't
underestimate. So $21 in plastic. So if you throw a significant amount of capital investment
at the prospect of building injection molding tooling, then that could come down significantly.
Remaining bill of material was actually published to the DVD if I remember correctly. And I
mentioned there may have been some hiccups along the road. This bill of material is definitely
not accurate to the 30 cent mark because the phase change material concept ended up
working out to not just moderately inefficient to virtually unworkable, at least with the
energy storage system I selected. If you need your robot to go to the bottom of the Marriott
trench, the fact that it's a solid to liquid phase change as opposed to expansion and contraction
of a gas really work into your advantage. But if you're going for range and you don't
particularly want to be dragging bottom with seaweed, trying to get 3,000 meters of depth
with that process, probably not the most efficient use of battery storage.
So I think it was early May when I realized, wow, I've got a 200 volt pack or whatever and
it's browning out at 100 milliamps, 0.1 amps. I knew that coin cells weren't exactly like
lithium polymer RC plane batteries but I was a little bit blown away. So I needed a
plan B or plan C, I guess. So what I came up with was something a little bit more conventional,
trying to avoid 2 million.
It was a little bit more complicated than I thought it was going to be. So I went to
the tried and true electric motor linear actuator because if you remember, at the time my perception
was those weren't really an option because people wouldn't have access to a lathe and
mill. But with a 3D printer, that potentially changes. So I ended up using commercial off
the shelf McMaster car parts to build the assembly which you can see in white on the
actual robot now.
So the only change between what's on your DVD and what actually is here in front of
you is the white assembly. Everything else I was able to recycle between the sides.
So modular design is a good thing, I guess. The gray pipe was a really good choice.
Sorry about that. The gray pipe was a really good choice because it allowed for routing
of the wiring and ultimately acted as kind of a skeleton or a backbone for the entire
vehicle.
So what I learned from that process is 3D printing is awesome and the great thing is
when you're actually done with it, you don't have to go through an entire twisted new process
to design 3D printed or injection molded parts.
You're practically already there when you have a working prototype.
What I learned through the process, I feel like I actually hit a pretty good balance
between fail early, fail often and not making stupid mistakes for lack of playing with the
planning. I didn't build anything before I had complete solid model data. And that's
really valuable when you're trying to avoid these last minute crazed runs to Home Depot,
West Marine, AutoZone, whatever it is. If you have a complete bill of materials before
you make the first part, you know exactly what's going into the thing and you don't
find yourself running into these issues where parts are colliding with each other. And then
it was also extremely difficult to quantify whether or not the design decision was a good
or a bad one, such as the wax motor, until actually trying it.
It was a design decision trade-off to not use so much simulation. And I was pretty happy
with how that went. Because you can simulate the daylights out of a bad idea and then find
out that you wasted the last year doing, you know, FEA or CFD on broken design. And then
it's all wasted.
wasted. So prototypes can illuminate things that you otherwise wouldn't be aware of.
So I did this entire thing out of pocket. No grants or funding agencies. I actually
really like that because I'm accountable to myself and I don't have anybody breathing
down my neck forcing me to chase sunk costs or make bad decisions because, oh, I need
to save face over that $1,000 I wasted on wax motors.
On the other hand, I gave pretty much the profit of the design away for free on the
DVD this year. I probably spent around 15 grand on the project over the past decade.
So I would consider it a dubious appropriation of my retirement savings. But that was the
mission from the start. I wanted people to be able to build these themselves and kind
of empower themselves to.
To deliver sensors, communications devices, and payloads to remote destinations where
traditionally it would be prohibitively expensive at tens of thousands of dollars per vehicle.
And how that's possible is if your price is low enough, you can consider it disposable
and you don't have to pay somebody 40 grand to go out in the water and change the batteries.
So we'll see.
Ultimately, if you build it, they will come.
And if it's a good idea, hopefully people will say, hey, maybe we should build some
of these.
So where to go from here?
I didn't have an opportunity to test max depth because I only had one prototype as
of two weeks ago.
And I didn't really want to lose it out in the ocean scuba diving.
Like I guess I could have tried to put a dog collar on it and walked it with a leash.
But overall, it's disappointing.
It's disposable after my talk is over.
But the thing took over 100 hours to print and actually that guy right there put in a
significant amount of labor helping getting this thing ready for you guys' eyes.
So small applause for him if you're willing.
Thanks, guys.
So in terms of trimming vehicle, I can say with high degree of certainty this thing is
very positively buoyant.
There's a lot of stuff in here that I could have used more of a normal buoyancy foam polyurethane
or epoxy and glass micro balloons.
High crush depth, kind of unnecessary seeing as how I designed the vehicle with syringes.
But overall, a good choice.
So generally speaking, epoxy or urethane, I chose Paraffin Wax.
It's low cost and over half the dollar per pound of buoyancy I was seeing was either
epoxy or polyurethane.
So paraffin wax is like $4 a pound.
So very positively buoyant.
Every empty cavity in that entire thing has a specific gravity of about .5.
So it's really just a matter of how you distribute your lead and batteries at this point to make
sure that when the buoyancy engine is in a neutral position, it's standing about horizontal.
Because when the vehicle goes buoyant, the center of buoyancy moves forward on the vehicle
when it pitches towards the surface and the GPS chip starts rising up towards the daylight.
And when it goes negatively buoyant, the opposite happens.
So if you're in neutral buoyancy, you should be sitting around level in the water.
And it's really just a matter of adding weight and removing buoyancy foam as necessary to
achieve that.
I'm looking at around 40 to 50 milliliters of displacement.
So it's unknown at this time what the vehicle's velocity through the water is.
The more buoyant it is, the faster it's going to pop to the surface like a cork.
And your speed through the water is going to determine what the Reynolds number is.
And that guides, you know, things like what airfoil you select.
But first draft, I'd call it an alpha stage design.
And OpenGlider.com is where I'm going to be adding future revisions.
The one on your CD is rev 0.1.
And rev 0.2 will be on OpenGlider.com tonight.
And that will have the new white syringe-based assembly.
So yeah, in terms of research that went into this, this guy named Bruce Carmichael was
one of the pioneers of the airfoil you see before you.
It's called the X35.
And originally it was known as the Dolphin.
But if I understand correctly, they ran the Dolphin through a genetic algorithm.
And ultimately the Citation shaping of asymmetric bodies for minimum drag, that one, I think
was where I was able to find the coordinates for this design.
It does bear some resemblance to some other vehicles on the market.
And that shouldn't be too surprising, seeing as far as I can tell, we did use the same
curve.
Okay.
So it's like it's kind of an X-axis.
But you can kind of rotate around its axis to generate the main body.
Otherwise, the NACA four digit series, pretty common equation.
And I threw something in here that I found really fascinating.
It's the geometry of a blended-wing body morphing wing.
And that was the idea that you could actually design an entire vehicle around variables
and equations.
So you can change something like static.
You can change the shape of the wing.
wing sweep from 30 degrees to 15 to 25 degrees and rather than having a lot of hard engineering
labor going into remaking the entire design it just regenerates itself so very early on in the
process I was trying to stick that concept and I was pretty pleased I would change a variable from
like a knack of four digit you know 002 to knack at 005 you know kind of crazy and you know hit
rebuild and the model would you know regenerate itself with very little labor on my part one thing
I'd like to explore is potentially even doing a genetic algorithm around that concept to optimize
for parameters like speed through the water column and lift drag ratio so that's pretty much how I
got here the x35 took me like six months to a year to even find
I had no idea where people were getting this this curve from but I saw it in several places
ultimately it was just a mad google foo that was able to illuminate the the coordinates to build
this thing and in terms of other information on how to build an underwater vehicle I was
going to joke you know every story's hero has a favorite weapon Brock Sampson's bowie knife
will Smith's little cricket and flippers hot glue gun when you're trying to waterproof stuff I've
tried a lot of different things conformal coat epoxy potting pressure housings and overall
even paraffin wax actually you know it's not going to do very good in the Caribbean where the water
gets down near 80 degrees Celsius and so but it doesn't matter I just don't think it's gonna matter
pretty good job because when you pot your electronics in epoxy it's very
difficult to actually recover them or repair them if something blows up but
when you're using paraffin wax the the 80 degrees C melting temperature is
actually below the rated temperature for most electronics so if you decide you
want to change something about them and I've had to you can just use a hot air
gun or boiling water to rescue your electronics that said from a durability
standpoint paraffin wax even if you anneal it with a little bit of mineral
oil not the most durable thing ever so ultimately hot glue has been my favorite
approach to waterproofing and if you need something a little bit lower
viscosity you get you know down in the English muffin nooks and crannies then
they make low viscosity silicone RTV the acetic acid can potentially corrode your
electrical contacts but we're talking about disposable vehicles here it
doesn't have to last three years I've got electronic speed
controllers I potted for the RoboSpub competition two years ago that still
work and that was just you know plain-jane Autozone RTV compound and so
pretty much every beast of electronics on that thing are just either coated in
hot glue or RTV compound and it's pretty easy low-cost way of waterproofing
electronics so I guess at this time would be a good way to go for questions
question from the audience yeah that's a good question so one of the problems
with underwater vehicles that makes some kind of interesting to me is unlike you
know Mars Rovers you know easy environment you know aerial vehicles a
bunch of lightweights you know these people they're so spoiled with
underwater vehicles you don't get to talk to your robot after you let it go until it comes back on you because you know you don't control it it's a great practice
back to the surface at which point you know it's kind of a surface vehicle
until it goes back underwater snorkel depth style so no radio frequency
communication so it has to be pretty much all autonomous and the source code
I used with the IMU to actually it's called a Haversine formula it finds your
current GPS coordinates and your destination GPS coordinates and gives
you a bearing and the distance you need to go to get there so it's pretty much a
line follower robot that's what makes underwater gliders potentially so
successful as unlike you know mind detecting robots or you know anti
frogmen stuff they have a pretty basic mission which is go from point A to
point B so object avoidance potentially with sonar but you know suddenly when
your payload starts getting into the you know high dollar sonar stuff it stops
being so disposable at that point you know my 3d printed open glider may not
be the best choice of vehicles
so testing has been kind of an iterative process I've learned every time I stuck
in the bathtub early on it was pretty much with a small car battery and some
red and green wire hanging out hanging out of the thing underwater vehicles
can't actually be communicated with remotely using something called a
tether at which point they're no longer AUVs or UUVs or ROVs remotely operated
vehicles and I had two years of tethered vehicles and I had two years of tethered
vehicles and I had two years of tethered
decides to do when it gets in the water or how it sits in the water when you put it in
there and both of those things don't require a big swimming pool. Also a lot less terrified
shrieking swimmers running away from the evil robot.
It's the second one. So I don't really rely on pressure housings as a rule. I had to depend
on some amount of air cavity for the design fix and it's the most conventional thing about
this design was you've got little linear actuators driven by 3 volt gear motors. Actually I think
I have one. Anybody want one? I know audiences love things being thrown at them. Not you
Mark.
Speaking of that, anybody want a flight controller? $33 give me. Remember, two is one, one is
none. So bring spare parts. Sorry. I throw like a roboticist. More questions?
What are the wires hanging out the end of the tube on the back?
Oh, good question. So when you have like a tank light when you're scuba diving you can
actually make them water activated so they are only wasting battery life when you're
in the water and you're trying not to lose your dive buddy. In my case I don't have
anything smart like that on my robot so those wires allow me to disconnect the power supply
from the actual microcontroller because once I plug it in it just goes. And it's just
going until I unplug it.
Really good question. I was at an ROV conference and this guy who was super salty and had been
out in the field for a long time told me a really cool trick. You go to like Harbor
Freight and they'll sell these heat shrink packages, marine heat shrink, and it's just
heat shrink that's been lined with hot glue. And you don't need to use special heat shrink
or wire crimps. You can just take your wire splice, coat it in hot glue and run heat shrink
over it. And when you melt the heat shrink or shrink the heat shrink it will melt the
hot glue again and pull all the air bubbles out. Great question.
How does it stand?
Oh, yeah, no, I totally glossed over on that. Really good point. So I don't actually
have one buoyancy engine. I have four. And generally speaking you might have them towards
the top of the vehicle. I have them low on the center of gravity because I don't have
a buoyancy engine. I had two places I could put them, top or bottom. And the top was
all being used by syntactic foam or syntactic wax, buoyancy sand. And since that was more
buoyant than the buoyancy engines themselves, I have them down low.
And so I have broken the cross section of my vehicle into eight little slices of pie.
The top four are full of buoyancy sand and the bottom four, there are two pairs. So when
you trigger the two-on-two.
On the left, your left side is going to be more buoyant than your right side. So one
wing will lift up. And likewise, if you use the two on the right, it's going to change
the attitude the other way. So this is one unique thing about my vehicle design. Traditionally,
you actually move your battery mass, whereas I'm just having four times the buoyancy engines
that are typical. And finally, if you change buoyancy on the bottom two, then you'll just
go straight.
AUDIENCE MEMBER 2
AUDIENCE MEMBER 3
AUDIENCE MEMBER 4
AUDIENCE MEMBER 5
AUDIENCE MEMBER 6
Oh, good question. So I can say with pretty good confidence that my inertial navigation
system is not high enough quality to be U.S. munitions list grade, so that's totally a
Relief. Yeah, these are hobby components. So video game grade. In terms of actual like
integration of my, you know, velocity or, you know, whatever to get my position, I don't
really do any of that. I've been working a little bit in my free time with trying to
use fetal Doppler monitors, which measure the velocity of fluid through a baby's blood
to, you know, let you listen to the kid's heartbeat. Kind of cool. And they're essentially
homodynes, ultrasonic homodynes. And I've been looking at potentially getting some velocity
information from that. But pretty much I figure out which direction I want to go. And it's
a line follower bot. It says, I know I need to go either left, right, or straight. And
it dives and it comes to the surface and it says, oh, wow, I missed my target, but
okay, now I need to go. You know, it doesn't really look backwards, only forwards. Good
question. Thanks.
How deep have you tested it to?
Oh, bathtub depths?
Okay. Originally, I had a washing machine wax motor from like a, I think it was a Whirlpool
Neptune or something. And that one didn't get a lot of mileage simply because the fiberglass
thing went so terrible. It just didn't really work into the 3D printed picture. So then
I moved to a solder.
I was using silicone, high-temperature rubber hose and soldering irons and filling them
with wax. And I was browning out my power supply. Even though I only needed about 100
milliamps, it was still too much. And it would have been a pretty big design tear-up
to change my batteries. So I just changed my buoyancy engine.
Questions?
Yeah, what about sensor packages? How true is there for any kind of .
Is it all .
Yeah.
Really good question. So in the original solid model I designed around, I actually
made a solid model of the PX4 autopilot from DIY drones or, you know, PX. I don't really
know what that relationship is, but it's a really good board. It uses a publisher-subscriber
system. And so right now I'm only using the IMU, the MicroWii board for everything. And
one of the issues with that decision is, if you're going to be using it, you're going
to have to use the Arduino 1.5.2. It is so flash memory constrained that you can only
just barely compile the source code and include it on your DVD. In fact, if you try and use
Arduino 1.5.2 to do so, it's not going to work for you. You have to use Arduino 1.0.4,
if I remember correctly, and that will work. So I didn't remember to put that into the
slides, and I'm glad you brought it up.
So there is a reasonable amount of space, about one-quarter the size of an Altoid 10,
for, you know, a supervisory controller to supplement the IMU. The IMU is broadcasting
yaw, pitch, roll information that's already been fused. So it's pretty much relative to
your world body or world coordinate system. And it's really nice because it's publishing
it on the serial port, and it's also telling you ‑‑ oop, time's up.
All right. Any further questions or wanting to see the robot in person, you know, touch
and feel?
I'll meet you guys out in the hallway, I guess.