Brushless AD HOC servo

[bitternboy]

Hey,
Just throwing some ideas in the air for a build but have people ever used brushless + custom gearbox to power a lifter controlled with a reversable brushless ESC and something like an arduino for a sort of psuedo brushless-servo? It would be pretty taxing on batteries and a few possible problems spring to mind but was interested to see if anyone had used something similar?
Cheers, Jon

[Rapidrory]

I've been looking vaguely at upgrading the lifter on Richie to brushless, and there's no reason why it's not possible. You won't get fine control as brushless don't really do that, but who cares about fine control as long as it goes to roughly where you want it to and lifts another robot in the process :L You could even just give it end stop switches and eyeball the rest of it (which is the setup I currently have).

The other potential issue is starting under load, but If it's geared down to the sort of speeds needed for a lifter, it shouldn't have too much trouble as long as a suitably powerful brushless was used. A 2KW brushless would be a suitable size and more than adequate in a feather, though that may end up as more of a flipper with that sorta power :L

Would this be for a feather or a heavy? Feather is perfectly doable I would think... it might get a little more tricky in a heavy.

[shakesc]

Look at what the Aussies have done with 2000 lbs winch gearboxes and brushless motors
I have one myself but no photos handy

[Rapidrory]

If anyone does come up with a fine control high power brushless servo setup though, I could do with a couple for my final year project :L

[bitternboy]

Yeah, this would be a featherweight. Fine control may not be entirely possible but like you say, you only really care if it's up or down (although I was thinking about having the forks extend past both the upper and lower faces so a central position might be nice).
What's the final year project on?

[Rapidrory]

Hoping to build a powered exoskeleton... because awesome :P

[Max]

I assume you've checked out "The Hacksmith" Rory? His exoskeleton is pretty cool!

[bitternboy]

I can confirm that that is, in fact, awesome :P The hacksmith one was a bit of fun but I have a feeling that Rory + final year project rescources would result in something a bit more versatile.

[marto]

You don't really need any hacking to do this.

Farm boy
https://www.youtube.com/watch?v=0RdOmm1y-gU
and
again in Kojak (same gearbox)
https://www.youtube.com/watch?v=aPsFLzh-Fzs

Is just brushless fitted with a bit of play to a winch gearbox running off a reversible car ESC. Doesn't tend to jam too badly as the brushless stalls rather than having massive amounts of torque when you slowly retract.

[Danjr1]

I'm curious about winch gearboxes - when the power isn't applied, do they somehow lock? or would a lifter arm just fall to the ground if there was any weight on it?

[shakesc]

They will effectively lock due to the high reduction, they are something like 140:1

[Danjr1]

They will effectively lock due to the high reduction, they are something like 140:1

cheers mate!

[Niels - Team K.a.L.M.]

Winches also use wormgears quite often. The wormgear can turn a larger gear but not vice versa thereby locking in place.

[overkill]

All these cheap car winches use a special variation of a planetary gearbox to get their high reduction. One of the reasons they work so well with brushless motors is that they have loose fitting gears and lots of slop. That means the brushless motor can start turning with no load and the ESC gets sense feedback before the motor needs much torque to turn.