Team 449 Climber

[qscgy]

This is the climber prototype built by Team 449, the Blair Robot Project. We weren't sure how legal it was to use Velcro, so we build what I've been calling macro-Velcro: spinning "hooks" (actually just bolts) that grab a loop. There's also a slipknot that allows the rope to wrap around the winch reel a couple times before it starts bearing a load. We complete the climb in about 6 seconds. Questions/suggestions are welcome!

Video

CAD:

[messer5740]

Looks sick. What gear reduction are you using?

[qscgy]

Originally Posted by messer5740

Looks sick. What gear reduction are you using?

50:1 on a VersaPlanetary attached to a Mini CIM.

[Kevin Sevcik]

You have plans for something to trigger the touchpad before you run into the channel? You'd probably hit the touchpad first tilted sideways like that, but you might not if you went up especially balanced.

[ollien]

Originally Posted by Kevin Sevcik

You have plans for something to trigger the touchpad before you run into the channel? You'd probably hit the touchpad first tilted sideways like that, but you might not if you went up especially balanced.

Far from impossible. Just add some 2" sticks extending straight up (or whatever direction you're climbing).

[Kevin Sevcik]

Originally Posted by ollien

Far from impossible. Just add some 2" sticks extending straight up (or whatever direction you're climbing).

Nothing's impossible or even very difficult at this stage. It gets tough when you show up at your first competition with a climber at the very top of your robot volume, though. I think there's a lot of people forgetting that the challenge isn't climbing, it's pressing the touchpad for >1s.

[jojoguy10]

How much weight was that in the video? Looks like a cool design! (At least, it's not velcro anyway )

[qscgy]

Originally Posted by jojoguy10

How much weight was that in the video? Looks like a cool design! (At least, it's not velcro anyway )

It probably weighed about 40 pounds, although we designed it to lift 150. It's the frame (made of 80/20) from our 2010 robot, with a battery and electronics board attached.

[jojoguy10]

Originally Posted by qscgy

It probably weighed about 40 pounds, although we designed it to lift 150. It's the frame (made of 80/20) from our 2010 robot, with a battery and electronics board attached.

I'd be very interested to know how it performs at about 150lbs (maximum robot weight is 154lbs)

[Oblarg]

Originally Posted by jojoguy10

I'd be very interested to know how it performs at about 150lbs (maximum robot weight is 154lbs)

The gearing was selected very conservatively to ensure that we're on the rising side of the power output curve.

The current gearbox is 50:1. Mini-CIM output torque is listed at 1.4 N*m. Our winch drum is 1.25'' diameter, so .625'' radius.

Neglecting friction, we have:

(150 lbs * .625'')/(1.4 N*m * 50) = ~15% of stall torque.

Now, I have really no idea how big the frictional losses actually are in this system, but I don't think there's any way they'll take us from 15% motor loading to over 50% (which is peak power, i.e. the loading for which this gearing provides optimal climb rate).

Fully-loaded climb rate (using the frictionless numbers) is somewhere around 6'' per second.

Upon reflection, we could probably gear it a bit faster (we had done the math for the gearbox when we were considering a larger-diameter winch).

[T^2]

Your gearbox will fail you after a regional's worth of matches, maybe sooner. The aluminum ring gear will flex enough to allow the planet gears to ratchet, and you will lose the climb.

[Oblarg]

Originally Posted by T^2

Your gearbox will fail you after a regional's worth of matches, maybe sooner. The aluminum ring gear will flex enough to allow the planet gears to ratchet, and you will lose the climb.

Are you sure? The 50:1/mini-CIM combo is labeled as acceptable by VexPro's documentation, and as noted above we're not actually anywhere near the peak loading on it.

[T^2]

Originally Posted by Oblarg

Are you sure? The 50:1/mini-CIM combo is labeled as acceptable by VexPro's documentation, and as noted above we're not actually anywhere near the peak loading on it.

Catapult failure in first 2014 regional, canburglar failure in second 2015 regional. Similar physical setups.

[SuperBK]

Wait - there is a knot in the at the bottom end of the rope? Or, Are you planning to bring your own rope and its legal to have a knot at the bottom to grab onto?

[Bluejackets]

Without a ratchet how does it not come back down?