Quote:
|
Originally Posted by BurningQuestion
Last year, our team used a telescoping arm/ winch system for our pull up arm.
We used a latch that would prevent it from back driving. The latch would engage/disengage from a notch in the winch drum whenever we wanted it not to back drive (the operator would press a button to latch the winch). It was spring loaded to pop into the notch, but we used a servo to hold it out of the way until we wanted it to go in.
It was very simple to make actually... we used two FP motors, with the FP gearboxes and "drums". We bolted the two drums together to make one big one... so we had two FPs bolted together, mirror images of each other. We then notched out the the raised portion of the winch where the two drums met together... with a hacksaw. As for the latch, it was just a rotating metal bar, pushed down toward the notch by a spring, and help up and let down by a servo.
The whole concept and implementation of this mechanism was really quite simple. Let me know if you don't quite understand how it worked so that I can find a picture or whip up a paint sketch. 
-- Jaine |
That is very similar to something what we did. It worked very well.
Quote:
|
Originally Posted by Michael Greenley
My advice for a mechanical solution would be to include a worm gear to prevent being backdriven.
Other options would be to leave the calibration off-true just enough as to equal the force down so that at 'rest' the motors would turn to fight being backdriven. As a general warning, the first method is a tried and true method. The second is me thinking on my feet (ok more-so thinking on my tush).
|
Personally, I stay away from worm gears as much as possible just because of the reason, "loss of efficiency".