That’s amazing Dave. Where are you located? Keep us updated on the foam and be sure to share that video if it works out. I may consider making some syntactic foam metioned in another thread on here.
I am in Orlando - I am the co-founder of Formula H20, an underwater racing league. We have a race this weekend in Weeki Wachee Florida. I plan to use the ROV to shoot the races and the mermaid shows.
Here is a link to a show featuring one of races.
The wreck with the Grouper spawning in called the USS Muliphen of the coast of Stuart Florida.
I will post some video this weekend of the ROV in action at the races.
So I ordered twelve (12) of the 1-1/4 inch foam floats, so I’ll see how they do.
Another option I was told about was the use of Divnycell Foam, which seems to be what a lot of the scuba divers use for their equipment. I bought some of the H-100 foam, so I’ll have to do some pressure testing, but I can at least order this foam without having to get a custom quote. The H-250 looks to be way overkill for my needs. http://www.aircraftspruce.com/catalog/cmpages/divinycellfoam.php
I am thinking of a slightly more elaborate solution. My thought is to design and 3d print a mold that will fit above, and contour to, the thruster. Once I have that mold ready, I can fill it with syntactic foam that is discussed in another thread on here. Unfortunately I have more ideas than time and don’t know 3d design/cad programs quite well enough to pull this off yet. If anyone else thinks this may work and wants to contribute, let me know. I think this could be a really clean solution, or I could be totally wrong.
I think that could work really well. With the 3d printed shell for structure, I think you could use a very low density foam instead of syntactic foam. You might be able to use an expanding insulation foam.
I know that this thread is over a year old, however I am interested in how well the T100 Thrusters worked with your OpenROV 2.7 Controller Board as the T100 Thrusters draw about double the current that the OpenROV brushless motors do. Also, I think that OpenROV reduced the current carrying capacity of the ESCs on the 2.8 Controller Board which further acerbates the higher current consumption of the T100 Thrusters issue.
Did you adjust the value of the Thrust parameter in the OpenROV cockpit down to say 2 - 4 to prevent over current damage to the Controller Board ESC power circuitry?
I never had an issue with the 2x T-100s and 1x M-100 on my 2.7. I simply dropped in the new BR hardware and it’s been working fine. I used it on power settings 2-4, not necessarily because of overload, but because at 5, it was too powerful and would pitch a bit downward. 2-4 kept it nice and straight.
Actually, it’s still working like a champ and was just loaned out for helping to film a TV show for 4 weeks and the users had no complaints.
Also of note, my large 6 thruster ROV used a 2.7 board with 6 thrusters and I didn’t (surprisingly) blow anything up. https://forum.openrov.com/t/work-class-openrov/674/101
Thanks for the information, much appreciated.
It is hard to believe that you were able to get 6 of the BR Thrusters to work with the OpenROV 2.7 Controller Board without having an over current event during operation.
Your 6 thruster design is most impressive. I am attaching a picture of my vectored 6 thruster ROV for comparison. It uses a BBBMINI as the navigation controller and has a separate battery WTC.
Did you build the navigation controller WTC for you 6 thruster ROV from scratch or did you cut down an existing OpenROV WTC and chassis?
The charges to laser cut the Topside Adapter case and the controller support structure in the Electronics Tube is about $70USD and that does not include the WTC water tight end-caps which I do not need in my design.
I used a stock OpenROV 2.7 Tube and 2x endcap kits. I doubled up one side with 6mm flanges so I was able to pot 6 more servo wires into the end cap. Seen here: https://forum.openrov.com/t/work-class-openrov/674/69 I originally built it for 3 thrusters, and while fine, I wanted to experiment with 6. I had the foresight to pot the extra servo wires, which I thought might have been used for 6x T-100s with BlueESCs, but I was cautioned against that as I would draw too much power and the ESC’s would be powered when the battery tubes were sealed up. Too many issues, not enough low cost solutions.
At the time I was building it, the BR 4" WTCs were just coming out and it was a bit late to change my design. I had considered upgrading, but when I was shown the BlueROV2 prototype, I ceased all R&D work of my own. The BlueROV2 has far more power and is more maneuverable than anything I could build.
Yep, I’ve been following your design for some time…what are you building now with the OpenROV stuff?
Thanks for the information on your build, but I am still a little confused on how you constructed your Controller WTC. I understand about using the OpenROV WTC and End Caps.
Did you have the Controller Electronics Tube acrylic support hardware cut from the OpenROV laser patterns or did you have previously existing Controller acrylic support hardware?
Presently I am putting together a three thruster ROV using the OpenROV 2.8 Controller and am thinking about duplicating the OpenROV WTC Controller housing instead of putting the Controller in a WTC that is parallel to the ROV sides and not perpendicular.
My mistake on the understanding. So it’s a bit of a weird story on the E-Chassis…As you saw from this thread, I completed a stock OpenROV 2.7 kit #1790 in March 2015 with the additional BR thrusters.
I bought a new E-tube and endcaps for my new 3 thruster design and once that was complete, I transplanted the whole E-Chassis from #1790 into the larger frame 3 thruster variant. The two were interchangeable so I had no need to build a new chassis at the time. When Walt sent me the prototype 6 thruster Controller Board, it was an easy swap out. When I visited OpenROV HQ in January 2016, Brian G was kind enough to give me a spare 2.7 chassis kit so I had two fully functional ROVs again.
Hope that makes a bit of sense. Best of luck with your new design, should be an interesting build.
Thanks for the clarification, much appreciated. That is what I figured you did, but wanted to be sure.
If I do duplicate the OpenROV WTC I will have to have the Controller chassis supports laser cut, however if I go with a configuration that has the WTC parallel to the ROV chassis sides I will have to make my own Controller chassis supports.
I plan to use a BR 4" diameter WTC and BR O ring flanges and end caps no matter what configuration I build.
Concur with using a BR 4" WTC, those things can go deep and it was pretty fun when we personally tested to 200m. Besides hydrodynamics, what is your reason for wanting the WTC parallel to the sides? I’ve seen plenty of ROVs with it perpendicular (Outland 1000/2000, Teledyne Mini Rover come to mind).
You will notice that all of the BR ROVs have the WTCs parallel to the sides of the ROV so there must be some advantage to this kind of configuration.
The OpenROV ROV is one of the few hobby ROVs, that I have seen, with the WTC perpendicular to the sides of the ROV which, in my opinion, appears to make that ROV harder to balance fore and aft. I have had no problem easily balancing my vectored 6 thruster ROV chassis and it has two WTCs that are mounted parallel to the ROV sides and are centered over the center of the ROV chassis.
The Teledyne Mini Rover’s WTC appears to be small in relation to the overall chassis so putting it perpendicular to the sides of the ROV chassis and right up front probably has very little effect on the ROV COG which is what I am looking for in a ROV configuration.
@TCIII and Kevin,
I think both options can work well. There are a few disadvantages to the lateral tube configuration that have led us toward the longitudinal design with a dome.
- The air-acrylic-water light path causes the camera’s field of view to decrease when you have a flat acrylic plate in front of the camera. The difference can be pretty dramatic (like 110 deg reduced to 65 deg if I recall correctly). In our design, we use a dome, which fixes this entirely and has no distortion.
In the lateral-tube design, you can mount the camera close to the acrylic, but your field of view will be reduced, or you can mount it close to the center of the tube, but then the image will be distorted. It’s distorted because in this position it is basically a dome shape vertically but a flat plate shape horizontally.
- With our enclosure and penetrator design, you need a lot of space at the end of the tube for the cable penetrators. That means that for a reasonable sized tube you need a very wide ROV.
For us, the longitudinal-tube design works out better.
Thanks for the technical pros/cons Rusty, I didn’t realize the field of view changed that dramatically. I guess it’s just in the way manufacturers build things then.
I just received a OpenROV Controller chassis acrylic components quote from Polulu and it turns out that the Controller Chassis end plates are only 3.66 inches in diameter which is over a 1/4 inch smaller in diameter than the inside of the OpenROV acrylic Tube which is supposed to have a 4 inch diameter inside. What gives?
Did you check the dimensions on the “Preview” PDF from Pololu before ordering? Sometimes the sizes of things in DXF files don’t get translated very well. The files you have might be set up with strange units.
Yes I did and I figured that I might have to adapt the Controller Support Frame End Caps to the WTC which will not be that difficult. The Frame End Caps are not the same as WTC End Caps that have the rubber O ring seals and I think are smaller in diameter than the WTC End Caps.
Polulu can only work with the DFX files and the DFX files are one of three available for the OpenROV 2.8.
As far as I can tell, there are no OpenROV frame component dimensions available to use for comparison.