Under Development Page on the Wiki


#1


We've added a new "Under Development" Page to the Wiki. This is serving as a bit of a cliff notes to the OpenROV forums, with links to relevant discussions and directions that members of the community are pushing the development. I think it could eventually help to organize different teams who are working on different aspects, but this is a good start for now.

Also, as Simone mentioned, this shouldn't be confused with the modular extensibility of the OpenROV, which is a high development priority as well. Simone also came up with my new favorite word, "thinkering." Awesome!


#2

I eagerly await more information and documentation on the cape development. For now it seems all there is is the schematic repository, which is rather helpful, but doesn't go into depth as to why each feature was chosen (eg. voltage converters, power redundancy, overvoltage protection, additional headers for sensing).

Whoever it is you have working on this is pretty brilliant, I must say. 22.2v down to 12v at 95% efficiency while supplying 3A of current looks solid in terms of motor supply. I wonder though, will it be able to handle the burst currents from the motors during startup? Theoretically they'd pull quite a bit more than that, but since I have nothing to test with at the moment (Motors and ESCs should be in within a few days!) It's all speculation.


#3

Hey SringHalo!

The power for the motors goes directly from the batteries to the ESCs (motor power is not regulated through the cape) so the 12v supply need only power whatever is attached to the AUX out (such as lights) and other peripherals.

If you plan to use lithium batteries with higher voltage for your ROV, be aware that the ESCs may not be able to handle that amount of power directly (some high power regulation may be needed). Online specs say that they can handle 3S batteries (three LiPos in series which is about 11v) but we've certainly run them higher then that. Testing is needed!

We'll try to get some more details about the cape architecture philosophy on the site soon.

Anyway, good luck with your project!

Eric


#4

with the lithium batteries i would rather run 3 batteries in series, and the two tubes in paralell, then you'll have 11.1volts nominal, and 12.6V when fully charged, and double the amps both in runtime and delivery. getting esc's and motors that can handle 6 lithium in series would be very expensive, and not right for a project like this.


#5

Thomas, I agree. Since lithiums can generally source more current then alkaline batteries, I guess it's not as necessary to exploit the extra voltage as a buffer to keep the 5v reg attached to the computer happy when the motors are running.

I was trying to think of a way to make it so either alkalines or lithiums could be put in the battery tubes without rewiring, and I suppose the best solution would be to have both wires from both tubes go into the end cap to a power bus, and the configuration (series or parallel could be switched there. Adds an extra conductor to the wiring harness but it would probably be worth it.

Hmmm....

E


#6

I'll check how two extra 18awg fits through the opening in the end caps - it will be tight, especially for those using an ethernet cable. Seems like that configuration would allow for more flexibility in the design which, generally, is a good thing.

We threw a european screw terminal in the kits, so there is a bit of flexibility in how that gets configured.