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
Passive hooks roughly on where your robot wants to stop.
Could you elaborate please. Thanks!
Could you post pictures of the climber? It could be an easy fix.
Have you considered engaging a ratchet-like mechanism 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?
Which is why you would engage the ratchet as you are retracting the climber/going up, preventing motion in the extend direction.
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.
Here are some pics: http://imgur.com/a/91JcU
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
Not the greatest example, and I’m having trouble finding examples from this year, but something like the black hooks on 1986’s Kraken 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!
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?..)
Usually teams cut off half of a ratchet wrench.
Usually tools are not left in the robot on purpose 
And when they are, you either find a random wrench on the field… or very baaaad things happen. 
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 See you there.
And we get past Semi’s this time? 