Vectored Thrusters: Alignment

[KR2_Diving]

Howdy all!
TGIF!

So my project goal for the weekend is to work out some of my design unknowns. (And to clean up my PS2 Controller code!)

For those of you that have played with Vectored Thrusters, have you done any work on what angle is the best? Originally I was thinking of mounting 4 motors at 45deg angles to the corners of my ROV. I then read the Technical report by Perdue's 2011 MATE competition team, and I see they picked an angle of 20deg.

Here is a link to the team page. (I think I actually found the link through the forum anyway!)
https://sites.google.com/site/purduerovhybris/

You can view the report and all other files here:
https://sites.google.com/site/purduerov ... le-cabinet

Anyone have any experience on this topic?

Thanks,
Ryan "KR2_Diving"

EDIT:
Found this research paper online... seems to be the answer to all my questions, but I am no Einstein! My eyes glazed over half way through the introduction...
http://imtuoradea.ro/auo.fmte/files-200 ... bref_1.pdf

[DavidF]

No real experence but I would have to think the angle would be proportionate to the distance between the thrusters. The closer together the more angle you would want and the farther apart the less angle you would want (for forward motion only). 45' sounds like way to much, but with thrusters mounted at all 4 corners running just the thrusters on one side would give you a sideways motion at near the same rate of speed as its forward motion. Guess it depends on what you want to do, be very manuverable or have good forward speed?

[martinw]

45 degrees allows for equal thrust in all four quadrants of the compass. Changing the angle provides a bias, either forward/aft, or lateral.

One of the ROVs we make (Sub-Atlantic Mohican), you can change the angle on the fly so to speak, in order to fight against currents whilst carrying out a task.

Martin

[KR2_Diving]

45 degrees allows for equal thrust in all four quadrants of the compass. Changing the angle provides a bias, either forward/aft, or lateral.
Martin

Thanks Martin! I was wondering if this was the case.

The Sub you mention, is it more square or rectangular? From I have been reading, the more important consideration is to be perpendicular to the diagonal axis.

Am I on the right path with that logic?

Ryan "KR2_Diving"

[martinw]

Hi Ryan,

It's roughly square but we also have rectangular ones too.

Not too sure about the perpendicular to the diagonal requirement but having the thurusters in the right place on the horizontal axis can be important, so the ROV doesn't porpoise along, bobbing up and down as it were.

Martin