TapeMeasure Climber Dropping after Match End

[dirtbikerxz]

We are attempting a tape measure climber system for our regional this week. We are essentially using two 775 pro motors to extend and retract the tape measure. (we are using the tape measure itself to climb).

One major problem we are having is staying up, after the match ends and the power is cut. The weight is too much for the 775 pros and the gearing to hold with no power, and the bot quickly slides back down. What are possible solutions to remedy this?

Thanks in advance

[CalTran]

Passive hooks roughly on where your robot wants to stop.

[dirtbikerxz]

Passive hooks roughly on where your robot wants to stop.

Could you elaborate please. Thanks!

[Clayton Summerall]

Could you post pictures of the climber? It could be an easy fix.

[EmileH]

We are attempting a tape measure climber system for our regional this week. We are essentially using two 775 pro motors to extend and retract the tape measure. (we are using the tape measure itself to climb).

One major problem we are having is staying up, after the match ends and the power is cut. The weight is too much for the 775 pros and the gearing to hold with no power, and the bot quickly slides back down. What are possible solutions to remedy this?

Thanks in advance

Have you considered engaging a ratchet-like mechanism (https://www.youtube.com/watch?v=LdvysdJJXW0) to prevent backdrive after your climber has extended? Or possibly a pneumatic disk brake?

[dirtbikerxz]

Have you considered engaging a ratchet-like mechanism (https://www.youtube.com/watch?v=LdvysdJJXW0) to prevent backdrive after your climber has extended? Or possibly a pneumatic disk brake?

Well we also have to retract once we are extended, so the ratchet would prevent us from doing that....right?

[EmileH]

Well we also have to retract once we are extended, so the ratchet would prevent us from doing that....right?

Which is why you would engage the ratchet as you are retracting the climber/going up, preventing motion in the extend direction.

[dirtbikerxz]

Could you post pictures of the climber? It could be an easy fix.

I am at home, but I just texted some guys still at the shop to send some pics, i'll post as soon as I get them. But to describe, the tape is rolled onto a wheel (essentially how it is in the inside of a normal tape measure), but we have two 775 pros geared together to roll that wheel in and out so the tape is extended and retracted. The tape is held onto the wheel by a bunch of 3d printed rollers on the outside, applying constant pressure, and guiding the tape in a straight line.

[dirtbikerxz]

Could you post pictures of the climber? It could be an easy fix.

Here are some pics: http://imgur.com/a/91JcU

[RoboAlum]

Easiest thing to do is the passive hooks we used for our tape measure climber it's a lot like a gate latch. But since then we just use a ratchet system

[CalTran]

Could you elaborate please. Thanks!

Not the greatest example, and I'm having trouble finding examples from this year, but something like the black hooks on 1986's Kraken (http://www.teamtitanium.org/#!2013-the-kraken-/cynj) from 2013. The concept, for instance, would be something like outside flat angled hooks that would ride over the bar but then catch later on and physically not let your robot fall.

[dirtbikerxz]

Not the greatest example, and I'm having trouble finding examples from this year, but something like the black hooks on 1986's Kraken (http://www.teamtitanium.org/#!2013-the-kraken-/cynj) from 2013. The concept, for instance, would be something like outside flat angled hooks that would ride over the bar but then catch later on and physically not let your robot fall.

Ahh, I see. This can totally work, thanks!

[who716]

i secound the ratcheting mechanism, we have ours attached to a servo, that locks it in.

[dirtbikerxz]

i secound the ratcheting mechanism, we have ours attached to a servo, that locks it in.

What material are you using as the ratchet (is that what its called?...)

[CalTran]

What material are you using as the ratchet (is that what its called?...)

Usually teams cut off half of a ratchet wrench.

[philso]

Usually teams cut off half of a ratchet wrench.

Usually tools are not left in the robot on purpose :D

[dirtbikerxz]

Usually tools are not left in the robot on purpose :D

And when they are, you either find a random wrench on the field.... or very baaaad things happen. :p

[philso]

And when they are, you either find a random wrench on the field.... or very baaaad things happen. :p

Yes!

We look forward to seeing your robot scale at Lone Star. Safe travels.

[dirtbikerxz]

Yes!

We look forward to seeing your robot scale at Lone Star. Safe travels.

And who knows, we might just do a repeat of last year and alliance up again :P See you there.

[philso]

And who knows, we might just do a repeat of last year and alliance up again :P See you there.

And we get past Semi's this time? :)

[Kevin Sevcik]

We're braking our tape-measure lift with a piece of rubber tubing attached to a Firgelli linear servo. We're using a WCP DS gearbox, so we have easy access to the gearing. The servo just pokes the rubber tubing into the mesh of one of the gears. The only annoying thing is we currently can't leave it engaged during the lift because during retraction it gets sucked into a different mesh and pulled off.

Still, if you can identify a mesh inside that toughbox nano that you could jam with a piece of tubing, you might be able to cut an access hole in the side and do something similar.

I've got a second linear servo coming in today or tomorrow because someone (Joshua Bryant) slightly broke our original, and it's been acting mildly flakey. I could give you the mildly flakey one, but it'd be mildly flakey.

[who716]

What material are you using as the ratchet (is that what its called?...)

We had these solid steel ring hanging around that we cut off our gearboxes every year. We machined ratcheting slots into this and attached it directly onto the shaft In which the winch pullies are on. Then we attached a servo to a piece of metal so that when the winch is pulling down the ratchet rides over the servo but when it goes up just a second the ratchet locks in. The spring is simply to prevent the robot from falling if power is cut to the servo for any reason specifically the end of the match and we didn't fully climb the spring overrides the servo and locks the ratchet

[Cam_Team 2619]

If you would like some help with a pneumatic disc brake, our team used one to stop our lift from backdriving last year, and therefore I have a fairly good understanding of how it works.

[PeeDiddy]

A simple way to eliminate back drive would be to toss a worm gear (looks like twisty pasta) in the gearbox.