Work Class OpenROV


#1

Greetings

First a little introduction before I jump into my design project. I am a 26 year old Lieutenant in the US Navy and my primary job is driving the "big grey things". I currently do not own an OpenROV due to me being on my 3rd deployment, but I plan on buying one as soon as I get back. My degree was in Military History, a bit different from everyone else in this group as I'm no engineer, but I specialize in researching and finding things. My other hobby is large scale RC warships so I do have a knack for building things.

In addition, I own my own 33' fishing boat, which is due for an electronics refit this summer. I also plan to outfit her with an A-frame for survey work. I have already started on my purchase of a towed PPM magnetometer and the side scan sonar is next on my list.

I grew up in Southern CA and underwater exploration has always been on my mind. I remember reading all the Clive Cussler novels when I was a kid and got scuba certified when I was 15. I got advanced certified when I was 17, but time, money and lack of buddies meant my plans were a little curtailed.

Last year after my second deployment, I spent much of my free time researching all the known shipwrecks off Southern CA. It seems as though every wreck within 100 feet (30m) has been found, identified and documented numerous times by local divers, but almost everything after that is a mystery. The UB88 team (www.ub88.org) has done a good job of finding almost every military wreck in the area so I don't really want to step on their toes.

I looked at what GUE Seattle had been doing to locate wrecks in Puget Sound, adopted their technique, and used NOAA bathymetry and 150KHz side scan sonar imagery to identify roughly 50+ unidentified targets down to 300 feet (100m). I established 300 feet as my maximum working depth due to this being my side scan sonar's maximum depth, OpenROV's maximum depth, and about as deep as I can anchor before I need a dynamic positioning system for the boat.

With these targets in mind, my next step is to conduct a survey with the side scan sonar and magnetometer towed behind it to see exactly what the 150KHz SSS data was picking up. If it looks interesting or is just not clear enough, I'll need to send down an ROV to take a look. My end goal is to make a little web-based TV show kinda on the basis of "Treasure Quest" from 2009 on how they went down and identified shipwrecks.

And this is where OpenROV comes in. I REALLY like the design with the computer onboard the ROV instead of having everything topside. It makes it more than just a "floating eyeball". The ability to get telemetry and feedback is the standard that "serious" ROV's are held to and I am glad we are going that route. And considering that the next closest cousin is a VideoRay from anywhere between $10,000 to $40,000, an OpenROV makes way more sense.

In it's current state, OpenROV is rapidly become a great undersea tool as an observation class ROV, but for the purposes I have planned, I need to make some changes.

1. Stability: As of right now, OpenROV is great because it's small and easily deployable. It sits slightly positively buoyant. Great for casual observations, but the ROV moves around widly whenever thrust is applied. This is pretty easy so fix, but it will make the ROV larger and heavier and a little harder to deploy.

2. Larger frame: As mentioned before, the frame will need to be made larger to make it more stable and I will need more attachment points for some of the tooling I plan on installing.

3. Wet-Connectors: I know potting is way cheaper, but it takes out some of the flexibility of the ROV once everything is "hard wired". Wet-connectors will make swapping out motors, lights and accessories much easier.

4. Topside power: I have a feeling everything I want to add is going to eat through batteries pretty quick, so I'm probably going to have to look at powering the ROV from topside. This is going to need a larger tether, etc.

5. Clump weighted tether: To work at the bottom in open water this is a must. Looks pretty easy to implement, but will restrict the maneuverability of the ROV to 100-200 feet around the weight.

6. Improved thrusters: I know this has always been a hot topic and I will be interested to see what the group comes up with.

The design I am looking at altering the OpenROV to is the Outland Technology ROV 1000.


Build a new frame out of heavy duty plastic with floatation on the top and mount the components as shown. Most of what already exists can be readily adapted without having to change much to the E-tube. Does anyone have plans for the Outland 1000 I might take a look at? Or know what thrusters they use? Maybe a materials list?

After the initial frame is done, here is the additional tooling/features I would like to install:

1. Downward facing GoPro with additional lighting. This would be used for creating photomosaics of wreck sites. I'm learning that imagery is far more useful when it is complete and photomosics, while complicated and time consuming are the standard in the field. Can be added without too much work.

2. Two servo based manipulators: With the recent addition of waterproof servos from Traxxas, I would like to take a crack at making a multifunction manipulator arm instead of just a "grabber" with no dexterity. One drawback to using servos is that it won't be able to lift much, but that's ok with me, I'm not ripping up wrecks or anything intrusive. Control is going to be an issue and I am not quite sure how I want to implement it yet. It looks as though a PS2 or Xbox controller will work.


3. Venturi suction dredge: These are relatively easy to make, but directing the suction end requires a manipulator arm. A filtration system will be added at the back to remove any wreck debris.

4. Suction cup attachment to one of the arms: Again not to hard to make, but does require a manipulator arm.

5. Scanning Sonar: Although the Tritech Micron is vastly out of my range ($15,000), new less expensive technology is becoming available as used in the Lowrance Spotlightscan and Humminbird bow mounted AC 360 scanning sonars. Very useful for picking objects out of the seabed if we can somehow integrate this technology.


6. Ultra-Short Baseline positioning system: Tritech already has this technology available, again for a price ($20,000). I like the conversation here and I’ll stay tuned to what comes about.

Thoughts? I know it's a bit complicated, but I feel like I can contribute a more stable frame and get the downward facing GoPro with additional lights working. This would be all I need to make photomosics and conduct pre-disturbance surveys.

I can’t wait to get home and start work on my own and start contributing!

-Kevin


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#2

Hi Kevin:

Thanks for posting this. If you could hang around OpenROV headquarters in Berkeley one afternoon, you would feel right at home- it turns out we discuss pretty much all the same things that you do.

Because our longer-term goals extend way beyond just a small 2kg ROV, we try to keep modularity and future expansion in mind with every new bit of hardware and software we design. For the Rev 2.5 OpenROV, it would be a pretty straightforward task to slide out the electronics and software, and adapt them to a much larger mechanical structure. You will need new thrusters and motor controllers, and will have to rethink the battery system, but other than that the basic electronics can stay the same.

I think by the time you've built an OpenROV and used it a while, you will have a really good idea of how to mix and match various components to make your own custom ROV.

You mentioned thrusters. If you want full-on professional ones, check out Tecnadyne. They will be expensive, though. For a more reasonable price you can look at the thrusters made by Crust Crawler. But in the short term it's probably easiest to just scale the idea we're using on OpenROV, which is to leverage highly off of the RC model market. Pick some big outrunner brushless motors, couple them with some props for a big model boat, and use an appropriate speed controller (ESC). If the interface to the ESC is the standard 1-2 msec servo, it will plug right into the existing OROV controller board.

BTW, what kind of sidescan do you have? I've played with a couple of different Starfish units, and have thought about getting a bigger and more capable unit. I would design my own, but OpenROV is sucking up all my free time right now :-)

Keep us posted on your progress- we're interested in hearing all about it.

-Walt


#3

Hi Walt,

I would love to come up one weekend when I get home if you would have me. I'm not much on the programming side, but I can machine a bit.

Yeah I know I'm a bit pre-emptive, but deployment is usually my time to research things for when I get home. I plan on throwing together a Rev 2.5 and getting that up and running and then order/build the larger custom one piece by piece. The key is to follow your example and make it as "off-the-shelf" as it can be. I have friends with large tools, so turning down end caps shouldn't be a problem.

For the thrusters, I've looked at the Crust Crawler thrusters before, and while they are brushless, they aren't magnetically coupled, which worries me a bit if I were to spend that much on them. I never knew about the Tecnadyne thrusters. They're brushless and magnetically coupled, but I can't find a price, and if they don't have their prices listed, I usually can't afford them.

I am familiar with brushed ESC's and have experience with the Mtronics Viper series, but I haven't gone into the realm of brushless yet. What type of brushless motors are you working with? Air, surface or marine? I know you pretty much have to couple the motor with the ESC. Is there a "too big" motor/ESC combo in our case? I don't want to fry the control board or anything by drawing too much power.

For the side scan, I looked at the Starfish ones as well, but the beamwidth is too wide to have any sort of "good" resolution to it and it doesn't tow very deep. I've looked into several other towfish and the next one up that I really like is the DeepVision DeepEye 340. (http://deepvision.se/) I've chatted with Jim Kennard, who used to work for Klein, and he swears by it. His findings are here: http://www.shipwreckworld.com/. It's got the most range and resolution at an affordable cost. I'm convinced and I'll be buying one after I pay off the magnetometer. I need the mag sooner to test and get adjusted. The boat is going to be outfitted with the new Garmin hull mounted side scan coming out in 2014.

Do you have an area you're looking at? The entire CA coastline has side scan and 3D bathymetry available. I have the GIS software to export whatever data to Google Earth. Let me know offline if you have a search area that you'd like imagery for and I can probably find you a few targets.

-Kevin


#4

Hey Kevin,

I've built an ROV similar to what you're looking for and currently have a DeepTrekker Pro with HD camera which we operate from our 40 foot sailboat down in San Diego. Let's chat sometime. I'm also a retired Navy BGBD (big grey boat driver). ;)


#5

hi kevin, I have been looking for a moderately priced mag. would you mined sharing which ones you have been looking at. that would be great, thanks.


#6

This is the one I have on order: http://users.skynet.be/fa352591/

It's not a mass production model, but it is affordable for me and I really like how the software is continually updated. Willy is great to work with and very flexible. Ask for some of the raw survey files to play around with if you're not sure.


#7

That is very interesting, thanks for the information! We are starting a build for a heavier duty ROV up here in Livermore CA. Once we get the aluminum in, a welding we shall go. The only other info I have on the R1000 is the pamphlet.

Comments on the thrusters, though. Original designs of roughly 3"x4"x2.5" using vectored thrusters after drag considerations for a target depth of 300ft was something like 6 ft.lbs, deigning 1.5x factor, so roughly 9 ft lbs. (my notes are not in front of me so I'm just throwing these values out from memory) I figured on using brush-less hi powered hobby rc motors with oil filled housings. Just started to think about that. As soon as I have the designs ready, I'll throw them your way for comment. Haven't worked out the power issue yet though. I think we are going to be splitting between on-board and PoE through the tether.

But thanks for the link to the magnetometer project!


#8

Jim,

I'd love to see what you guys come up with for the frame. Those thrusters sound like they might do the job. I think that is the way to go though for thrusters for ROV use: brushless, oil filled housings and magnetically coupled.

The power issue is a bit more unique. I've been reading through the "Tether" forum and Walt was saying the next revision is supposed to have a PoE option. I know this is what the OpenROV team has been working towards, so I won't try and reinvent the wheel here.


#9

I've updated my Facebook page with pictures of my magnetometer in case anyone wanted to take a look. I still need to purchase a 200m cable for it and build the towfish body before I can start conducting my surveys. ...and add in an A-frame to the boat...and a ruggedized laptop.

Endurance Marine Exploration


#10

A little update:

I just returned from deployment and I have my OpenROV 2.6 kit unpacked and I've started preparing for assembly. I still need some of the glues etc. I've waited 8 months to start working on this so you know how excited I am.

I also got my magnetometer in the mail. Everything works, but it is going to take 2 months for Falmat to finish the 660ft of underwater tow cable I need. Oh well, plenty of time to finish the towfish body and the modifications to the boat.


#11

Hi Kevin , great to hear it. Remember, be patient lol I am not and had a hell of a time fixing the internal frame after I messed it up. Haste makes waste

Can I ask you to post an overview if the mango meter when you have free time? I’d live to hear your opinions and review of the kit. I know the guys in Berkeley are keenly interested in it as am I and others here are. Thanks and good luck with the build.


#12

Thanks Jim, I'll be taking my time with this one. I was patient and waited for the 2.6 revision which seems pretty solid.

Sure, of course I'll do a review of the mag. I won't be able to tow it from a boat for a few months, but I might try a survey on land just to test it.

When I do get everything up, I plan on using the A.C.E. seiner wreck as my test site for my mag and side scan. (http://www.cadivingnews.com/article/920/ACE-Becomes-Southern-Californias-Newest-Dive-Site)


#13

Magnetometer not mango meter lol


#14

Jim,

Attached are some photos from my magnetometer tests this morning. I spent some time this morning tuning the magnetometer properly and testing it against a known item (in this case, a hammer and my car keys). The arrow points to the dipole (positive and negative of the magnetic field given off by the hammer), and thus the location of the item. No idea what the other positive and negative values are at the top and bottom of the survey area.


I am also providing regular updates to my Facebook page if anyone is interested: Endurance Marine Exploration


#15

Time for some updates:

I completed my first 2.6 OpenROV a few weeks ago, tested all the control systems and let it run around in the bathtub for a hour to check everything. I am very happy with my end result and the controls are fantastic, especially when using the Logitech F310 gamepad.

Some items of concern I noticed from testing are that even for even the limited amount of time I had the ROV in freshwater, the bearings on the motors started rusting. I had wanted to continue testing in Dana Point harbor, but I became very nervous after seeing this. The second concern was with the lights. Although I think their brightness and control are spot on, there is a lot of back-scatter from the acrylic cylinder even on the lowest setting.

With that in mind, I plan on keeping my stock OpenROV in one piece for testing purposes and moving on to work on my next version.

Unless a 2.7 is due out anytime soon, I’m planning on buying another 2.6 kit and modifying it like crazy.

I already bought a gripper and wrist rotation kit to get me started from Lynxmotion. http://www.lynxmotion.com/p-826-a-style-gripper.aspx

I got the waterproof servos from Traxxas.
http://www.amazon.com/Traxxas-2080-Micro-Waterproof-Servo/dp/B002BE

And I even found affordable wet-connectors for our needs from Amron.
http://www.amronintl.com/seacon.html
I decided to go with the Micro Wet-Con Series with 2,3, and 4 poles instead of the Rubber molded ones because the RMG series have very long connectors (nearly 6 inches combined). The Micro Wet-Con series are around 3 inches total when connected for about the same cost. And I can plug them in underwater :slight_smile:

Also today, I found a new maker of brushless thrusters: http://www.bluerobotics.com/thruster/
This looks like just the ticket for what I need and I plan on buying quite a number of them for future projects.

Pictures to come when everything comes in!


#16

Hi Kevin:

You can reduce the amount of LED scatter into the camera by adding black velvet swatches to the existing white plastic blinders. See this forum post.

As for motor corrosion, the existing motors actually hold up pretty well in salt water, as long as you carefully rinse, dry, and lube them after each dive. If you're going to be regularly working in salt water, you might want to consider pressing out the original bearings and substituting stainless ones. Several people have purchased stainless bearings for the motors via E-bay- I don't have the sizes handy but they should be buried on the forum somewhere.

-W


#17

Kevin, that’s fantastic, can’t wait to read about it. I’m in the middle of moving to the Cheasapeak so as son as I’m up and running I’ll hit you up about the magnometer and your plans for the new kit. I’ve started researching a full AUV version of this Kit planned for the winter


#18

Hey Kevin,

This is Rusty at BlueRobotics - I'm glad you found our thruster! Here's a few details to help you plan your ROV:

~5.0 lbf thrust

3.7" outer diameter

4.0" length

Max current draw is about 12A at 12V (~140 Watts)

The thruster can handle long-term exposure to saltwater with no problem and it has no depth limitations. We'll be releasing it later this summer. Your project sounds pretty awesome. I'm excited to see it come together.

- Rusty


#19

Rusty, great information, thank you! I've been reading everything I can on your thruster. 12A for a current draw is not bad at all and will definitely work with the existing ESCs.

Let us know when you start your Kickstarter campaign and I'll definitely pitch in. There really is nothing else on the market that I can get for a reasonable price and I'm glad you guys figured it out.


#20

Sorry terrible spelling mistake, that’s Chesapeake lol