Hi All,
I am sure that many of you have heard of the OpenROV Project which involves building your own ROV from a kit. I am an experienced model builder with plenty of experience and a reasonably equipped workshop, but I was a little taken aback at the complexity of assembling the OpenROV from their kit of parts. It seemed to me to be a high school to college level project requiring a small team of experienced modelers to successfully put the OpenROV together though I could be wrong.
It appeared to me that there were a number of critical assembly requirements that had to be performed spot on as there was no going back to realign or reseal once the assembly was completed. Therefore I have been looking around to see if there might be an easier way to design and build a ROV similar to the OpenROV without having to perform some of the critical assemblies required to complete the OpenROV.
One area of the OpenROV design that I took exception to was the thrusters. They were not going to last very long when immersed in seawater due to the exposed bearings and stator/armature. To me this was a kind of deal breaker as to the questionable lifespan of these thrusters. I know that commercial thrusters are not cheap (think Seabotics or CrustCrawler) and the OpenROV project was just trying to overcome the high price of commercial thrusters with their homebrew design. Still the unknown lifespan of the OpenROV design did not leave me with a warm feeling to say the least.
Then came along Blue Robotics and their T100 Thruster KickStarter Project Link. Their design approach looks good and they have actually tested and characterized prototypes of the thrusters they will deliver to the pledgers. With the addition of the in-thruster water cooled ESC this design becomes very attractive in that it reduces the number of wire penetrations in the Water Tight Compartment (WTC).
Great! Now we have a source of reasonably priced thrusters so what is next? Well, that is where you, the ArduBoat members, come in.
Let's start thinking about the WTC, navigation controller, communication, power, ballast, buoyancy, etc. and attempt to come up with a reasonably priced ROV that the average ArduBoat member might want to consider building.
Regards,
TCIII AVD
Replies
Hi
Yeah, so would I. The beauty of making my project open is that people like BigKahuna come along and make these great suggestions. At the moment I will stick with the RS232 on a slow baud rate seeing as the device is built now and undergoing trials. But if I proceed to a more refined design I will definitely be adopting BigKahuna's suggestion with the RS485. So thanks for getting in touch with me on that.
I suspect my success (aka "getting away with it") with the RS232 over the 100m tether is because I mistakenly bought a role of solid copper Cat5e rather than stranded wire. Of course this means the cable is not as flexible as it would otherwise be. I will see if that mistake bites me in the butt at a later stage.
I may have to adopt some of those Blue Robotics thrusters in a later edition too or manufacture some magnetic couplings. I am nervous about the OpenROV style of thrusters I have used depite having sealled them and hopefully made them more sea water resistant. If I ditch them then there won't be anything borrowed from the OpenROV.
Good luck with your projects.
Cheers
Hamish
Hi Hamish,
Nice to see that you have joined our ROV Project.
I have gone over your Arduino code and it looks good in relation to the code that was written by Nick Sopwith and still needs to be finished up.
Hopefully all of us together can do some suggestion/idea crowd sourcing in relation to our individual ROV projects.
Regards,
Tom C AVD
Hi David,
Linus and I are thinking about using a bbbmini that we have been working with recently. We have it working very well compared to the bbbpxffirecape though we could consider the Rpi and maybe a APM2.6 like Blue Robotics did with their Blue ROV.
There is an ArduSubmarine project in the works that can run on the bbb.
Regards,
Tom C AVD
O.K.. Just asking. I'm trying to get caught up with technology these days. I was a computer science major back in the early 80's and programmed a lot in C. Then lived and cruised on sailboats for about 20 years. Got off the boat about 5 years ago and I am trying to relearn everything again. I guess a 386 machine is no longer cutting edge technology. Just kidding but enjoying learning all this new stuff. Looking forward to the automated side off this project.
Regards,
David R. Boulanger
Hi All,
Today I completed the installation of the upper WTC support cradles on the main cross brace/WTC support. Tomorrow I will begin the installation of the lower WTC support cradles on the main cross brace/WTC support.
The pictures below show the location of the upper WTC support cradles on the main cross brace/WTC support:
Front View of Main Cross Brace with WTC Support Cradles Attached
Presently I am thinking of holding the WTC down on the support cradles with marine grade Velcro straps. The straps would wrap around both top and bottom WTCs through slots cut in the main cross brace/WTC next to the sides of each WTC.
Once the WTC support cradles and hold down straps are installed I will move on to mounting the four Thrusters in their respective horizontal and vertical positions. Then comes the more difficult part of this ROV project, the potting of the Thruster power and control wires in the WTC end cap cable penetrators. Fortunately for me Blue Robotics has several very good tutorials on preparing the cables for insertion in the cable penetrators and then their epoxy potting in the cable penetrator feed through shafts.
More to come.
Regards,
Tom C AVD
Hi All,
On Monday I glued the HDPE pieces of the WTC mounting cradle blocks together with the JB Weld Polyethylene/Polypropylene adhesive which worked great and finished cutting and sanding them to size on Tuesday morning. I then epoxied 1/8" thick rubber strips to the faces of the cradle blocks where they will contact the sides of the WTCs.
At this point I was ready to spot and mount the cradle blocks on the main cross brace/WTC support. I had decide to use ss 6-32 machine screws to attach the cradle blocks to the main cross brace/WTC support. To begin the spotting and mounting process I drilled two #36 tap size holes in each cradle block. The idea here is to be able to clamp the cradle blocks into position against the WTC tube and then use a #36 drill to spot a hole in the cross brace for each of the cradle block mounting hole pairs. The front of the forward cradle blocks was positioned flush with the front face of the main cross brace and tangent to the circumference of the WTC tube while the rear of the aft cradle blocks was positioned flush with the rear face of the main cross brace and tangent to the circumference of the WTC tube.
In the pictures below the cradle blocks can be seen clamped to the main cross brace up against the WTC tube. In the first picture I have aligned the cradle blocks to the WTC tube and the main cross brace and have drilled the first #36 hole in the main cross brace for each of the cradle blocks. I will then tap the #36 holes in the main cross brace with a 6-32 tap for the ss 6-32 machine screws. Since the clamps block one of each of the hole pairs in the cradle blocks, I must repeat the spotting process for the second hole after I have drilled and taped the first 6-32 hole for each cradle block in the main cross brace.
After I have spotted, drilled and taped the eight 6-32 cradle block mounting holes in the main cross brace I will counter bore the #36 hole pairs in each cradle block with a #28 clearance hole drill for the insertion of the 6-32 ss mounting screws.
Front View of Chassis with Centered WTC and clamped on Cradle Blocks
Chassis Left side showing the WTC and clamped Cradle Blocks
Tomorrow I will drill and tap the first cradle block attachment holes in the the main cross brace/WTC support and attach each of the cradle blocks to the main cross brace so that I can complete the spotting of the second cradle block mounting hole in the main cross brace. I will then drill and tap the second set of cradle block attachment holes in the main cross brace. At this point the upper WTC tube cradle mount should be done except for the addition of slots to be spotted in the main cross brace to allow the passage of marine grade Velcro straps through the main cross brace in order to hold down the WTC tube to the main cross brace while it is seated in the cradle mount.
More to come.
Regards,
Tom C AVD
Hi Thomas,
Is this the JB Weld product you used?
http://www.jbweld.com/collections/epoxy-adhesives/products/plastic-...
I would be very interested to know your evaluation of this product.
I generally use hot air or hot gas welding for polyethylene or polypropylene and have not been happy with any glue joints.
But I have not tried this product which appears to be a 2 part Urethane, not an Epoxy base.
I have found that generally epoxys do not bond but simply peel away (the smooth plastic normally makes a good mold release material for most epoxies.)
However urethane has a more adhesive nature to it so it does seem like it might work.
I use single part urethane glues on some foam models and they generally foam up and expand themselves - does this glue do that?
Your frame looks great by the way.
Best,
Gary
Hi Gary,
Thanks for the kudos, much appreciated.
The JB Weld adhesive in the link looks like what I used.
I bought mine off of Amazon for somewhat less.
I sanded each surface to be mated with 60 grit sand paper and cleaned each surface with 91% isopropyl alcohol.
The adhesive is not real flexible, but sure makes a good bond between the HDPE blocks.
I do not know how good its shear strength is with the HDPE, but I would not use it by itself to join two HDPE surfaces unless they are in a low shear usage like my cradle blocks.
Regards,
Tom C AVD
Hi All,
Today I completed the fabrication of the pieces of HDPE that will make up the WTC mounting cradle.
The mounting cradel is essentially a tower composed of three 1/2" x 1 7/8" x 1 1/8" blocks with the top block having a 30 degree angle cut on its inside face which will be tangent to the side of the WTC at its outer circumference. There will be four towers with two at the front and two at the back of the WTC and will center the WTC latterly on the main cross brace/WTC support.
I plan to use the JB Weld epoxy to glue the blocks together, sand to shape, and then drill vertical holes in the blocks to accommodate 6-32 screws that will hold the tower in place on the main cross brace/WTC support.
I hope to have pictures of the mounting structure by mid week.
Regards,
Tom C AVD
Like the new frame. Where'd you buy your HDPE from?
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