Acendtech Robotics is a 4H robotics club located in Freehold, NJ, and their centerpiece project is the Archelon, an underwater drone they built out of PVC pipes. It’s also a Hackaday Prize entry designed to monitor marine traffic, the seabed, piers, jetties, and other underwater constructions.
The Archelon uses eight thrusters constructed out of bilge pumps that have been hacked to add a propeller, leaving the motor sealed safely inside.
The ROV’s motors are controlled by an Arduino Mega along with two motor driver boards, each board driving two pairs of DC motors. There’s also a robot claw rotated by another modified bilge pump, opened and closed by a waterproof servo. The on-board electronics including a Teensy 3.2 are sealed inside a 1/2″ acrylic tube sealed with rubber o-rings and custom-milled stainless steel endcaps. Connected to the Teensy are the ROV’s cameras as well as an ATTiny88, which in turn control the motors.
Students working with the Archelon learn not only the technical aspects of building a ROV like assembly and programming, but also its mission, learning how to take test samples of agar to study pollutants in the maritime environment.
I hate these posts which only have hackaday.io link. No video, no photos, just promises. It’s like kickstarter :-D
I don’t understand your complaint. There are many pictures and a lot of documentation in the .io link. This is one of the better documented projects I’ve seen.
Harvie.CZ – Here is their video from 1-JUL-2017. It’s apparently a tethered test inside a swimming pool in where they pickup a white object on the bottom of the pool. Not very deep. I don’t see a lot of maneuvering but they are focusing on that object I guess. Also not sure why there is no video sound. Sound would be a good indicator of how loud those Seaflo bilge pumps are.
https://www.youtube.com/watch?v=b3pEydhPwIA
Hi! I have no idea why there is no sound. That video is from the first time we piloted the robot, and we wanted to practice picking up small objects because that year we needed to be able to pick up a lot of small objects. We were also just testing out the controls to see if they were easy enough to use.
Also, the bilge pumps are not very loud. They are mildly irritating when out of the water, but when beneath at least 2 inches of water you cannot hear them.
Okay, this is a great design/documentation/paperwork project, but there are a lot of “gotchas” in their design* (and I understand that it’s 4H kids and they’re pretty enthusiastic about it) – most of all, despite documenting everything down to the TPS report covers and with extensive checklists, charts and ebullient verbiage, there’s no indication that the device ever saw an in-water test run. IMHO This cheats the students from some of the “uh ohs” that precede real learning.
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*eg From the documentation: “Bilge pumps were chosen because they are brushless and therefore inherently waterproof.” They aren’t and they’re not. Unless they’ve substantially changed the design since I last rebuilt one (their documentation doesn’t indicate this), they’re brushed motors and are sealed for moderate immersion but not pressure proof.
Am fixing that. These bilge pumps have been used for many other ROV projects before, and have worked without any problems below 100 feet.
Nien – I think Cristian Arcega solved that particular problem with using some sort of absorbent textile mounted in the shell of the pumps. Not sure but the movie Spare Parts (2015) talks about it briefly. I think (and I could be wrong here) that after passing critical depth, the o-rings fail and water gets in fouling (or shorting) the electrical connections. Seawater is worse than chlorinated pool water or littoral water for doing that. Also temperature differences can cause internal condensation inside the shell housing, I think. I know the SEAFLO’s top operating temp is 110° F (43.3° C). So if the water is cooler than the nominal temp inside, condensation could be a problem. The absorbent would temporarily keep the water off of the electrical connections for awhile – but not long. I’m not going to say what they used, but it was a stroke of pragmatic genius, albeit mildly embarrassing to “in-the-box” thinkers….
I guess it all started here:
https://www.wired.com/2014/12/4-mexican-immigrant-kids-cheap-robot-beat-mit/
wilsonc4 – Yes NASA sponsored this program and discovered the next Dr. Franklin Chang Díaz (who is now 67 years old). The boy-genius they discovered was 16 at the time and was the high school’s team intellectual spear-head of this UUV ROV (named “Stinky”) that beat out the UUV’s from MIT and Cape Fear Community College from North Carolina. His name is “Cristian Arcega”. He is 29 now and was last working at Home Depot 3 years ago. This guy is a child prodigy with similar indigent background as the now successful Jim Carey (the comedian/actor). It’s ashamed this talent is going to waste. Dr. Diaz (Ad Astra Rocket Company) should seek him out and bring him under his wing. Dr. Diaz’s rocket motor is arguably going to be the “next level” right-stuff to get us farther out into outer space (i.e., VASIMR) . Or USN’s retired Dr. Robert Ballard should seek him out too (at Woods Hole Oceanographic Institution). The Acendtech Robotics club could use Cristian’s help.
The comedian George Lopez did a serious movie about this kid called: “Spare Parts (2015)”. Here is a trailer:
https://www.youtube.com/watch?time_continue=79&v=myjar5KoqZA
I have seen some motor/propeller units where the electrics were completely sealed and the prop was driven by some sort of inductive design – no shaft seals to worry about – seems to me off the shelf designed for what you want to do would be better
[Matthias Wandel] just did a tear down of sorts of a motor like that from a dishwasher. I doubt the housing would resist much pressure but that’s what mineral oil is for.
Like the pump drives used in JetSpray beverage coolers. http://www.ebay.com/bhp/jet-spray An impeller with a magnet sealed inside sits in a recess inside the liquid tub while the magnetic drive is outside the tub. Totally leak proof.
captnmike – True the 1100 GPH Seaflo Bilge Pumps they are using may be problematic after 50 feet (15 meters), but they are fully submersible and have marine blocking wiring. Not sure why they felt it necessary to add (hack in) a screw (propeller). Its GPH should be enough for diving, surface, maneuvering, and station keeping. Those screws (or impellers?) are only going to introduce weed fouling and small fish getting in there.
Induction drive is interesting but I feel will under-power the craft. I mean why not Red October “caterpillar” drive while were at it. All you need is some superconductors and liquid helium. :-)
https://www.youtube.com/watch?v=y7g6dKncO-I
If anyone is interested in UUV ROV’s here is a Western Australian ROV manufacturer that has submerged their UUV’s to 9,800 feet (3000 meters) off of Perth AU. They make them for the petroleum industry. This video was shot in 2013. As of 2015 they have 12 of them in operation in Brazil. Maybe some pointers or advice can be gleaned from the video. They list their contact info too near the end of the video I think. I put it here too I use [at] for @ and [dot] for a period.:
https://www.youtube.com/watch?v=b3pEydhPwIA
Total Marine Technology Pty Ltd
ABN: 70 086 117 660
Australia Office
1 Ambitious Link
Bibra Lake
WA 6163
Telephone: +618 9411 6500
Fax: +618 9411 6522
Email: mail[at]tmtrov.com[dot]au
Postal Address
PO Box 3054
Success WA 6964
Website: tmtrov[dot]com[dot]au
FYI: WA means Western Australia
SORRY ABOUT THAT! TOTAL CLIPBOARD SCREW UP… Here is the CORRECT video. Also shot in 2015 not in 2013 (sheesh!) :-(
https://youtu.be/mw5gdq9HCwo
Nien – If you can overcome your depth limitations to reach let’s say 300 feet (91.4 meters) of seawater. I have an interesting target for you to dive on in just 230 feet (70m) of North Atlantic waters. It is just 68 miles (109 km) from you southeast about 60 miles off of Atlantic City NJ (USA). The coordinates are approximately 39°32′56″N, 73°19′56″W. It was discovered in 1991 and finally positively identified 31-AUG-1997. It was a total WW2 mystery up until then. Maybe you could be like Dr. Bob Ballard and uncover even MORE secrets? Whatever you do just send the ROV down please – no divers. Take a few photos and bring it back up. Also look around the periphery for any other undocumented debris or wreckage further easterly. You might get lucky…
https://youtu.be/gBu55pelXzw
Also check out video: Shadow Diver on the U869 narrated by John Chatterton