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]

Originally Posted by CalTran

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.

[dirtbikerxz]

Originally Posted by Clayton Summerall

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.

[who716]

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

[dirtbikerxz]

Originally Posted by who716

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]

Originally Posted by dirtbikerxz

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

Usually teams cut off half of a ratchet wrench.

[philso]

Originally Posted by CalTran

Usually teams cut off half of a ratchet wrench.

Usually tools are not left in the robot on purpose

[dirtbikerxz]

Originally Posted by philso

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.

[philso]

Originally Posted by dirtbikerxz

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.

[PeeDiddy]

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

[who716]

Originally Posted by dirtbikerxz

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.

[dirtbikerxz]

Originally Posted by Clayton Summerall

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

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