Omni on the cheap.

[sanddrag]

If I wanted to make an inexpensive omni/kiwi platform with the wheels perpendicular to a radius drawn from the center (like 229 and 867 did), could I control it by a standard RC (stick type) remote and use this http://robotcombat.com/marketplace_robotlogic.html (scroll to bottom of page) I know there's not much info on this thing, but from your take on it do you think it could control the 229 or 857 omni/kiwi bot?

And I can use this with regular ol' RC speed controls (forward and reverse type) right?

How would it work? If I have a two stick remote (think Vex controller) then one stick would be both axes for translation and the other would be only one axis for spin?


For more on the "cheapness" of this project I'm thinking I can run on inexpensive Chinese (Nothing against the Chinese) 9.6V drill motors @9.6V (500 rpm) and 4" dual transwheels (plastic). And since it is only 9.6V, maybe I can use a regular RC speed control for each motor. The one I found is rated for 16A continuous 60A peak? Is that enough? I'm thinking it would be for such low traction wheels and an overall weight <35 lbs probably. In RC terms the speed control is rated for a "15 turn" motor which would be a "mild modified" I know the drill motor is a little larger than and RC motor, but it does have more turns (probably in the range of 30). Do you think 16A continuous is enough?

[Andy A.]

Sand-

I'm not entirely sure on the first problem, of mixing channels on an RC controller. I'm not really sure just how the control system needs to be set up (I've never really gotten my head around omni drives). I know that some very advanced (expensive) R/C controllers can mix channels to one axis, often for helicopter control. Some of the really nice controllers actually have rather advanced processing power, and can be programmed to mix and scale channels all over the place. But, you said you liked cheap...

As for the speed controllers, a lot will depend on the typical current draw and duration of run. Most hobby controllers are designed to run a fairly small motor for around 10 minutes at a time. How long did you want to run them? If it's rated for 16 amps, you can probably get away with 25 amps, for short periods. With a bunch of motors moving that light a weight, you can probably get away with it. You'll probably be limited by how much current the battery can supply anyways (unless you are using a lead acid type).

You might consider putting the controllers under a muffin fan, or some other form of cooling. Water cooling? Would add to the geek factor for sure...


-Andy A.