View Single Post
  #10   Spotlight this post!  
Unread 02-12-2012, 13:34
Chris is me's Avatar
Chris is me Chris is me is offline
no bag, vex only, final destination
AKA: Pinecone
FRC #0228 (GUS Robotics); FRC #2170 (Titanium Tomahawks)
Team Role: Mentor
 
Join Date: Dec 2008
Rookie Year: 2006
Location: Glastonbury, CT
Posts: 7,669
Chris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond reputeChris is me has a reputation beyond repute
Send a message via AIM to Chris is me
Re: Balancing an Arm

Quote:
Originally Posted by MrForbes View Post
And surgical tubing also has this problem, even more than the gas spring. The fun part is trying to get the geometry right so that it works the way you want, ie. naturally holds the arm retracted in the "stowed" position, then provides more help as the arm raises up. We haven't been able to do it yet, but one of these years we'll actually design this part of the robot.
The way we've found some success using surgical tubing is to pre-stretch it a little so that even when its in its most relaxed position, it's still providing a bit of resistance. It seems a lot of the nonlinearity is in the first few inches of elongation, so this seemed to work for us. Then again, arm balancing is the kind of thing you can just get "good enough" at.

Quote:
The 330 approach of using a lot more motor power, seems to be quite successful. I'd listen to Eric.
There's a lot to be said for just throwing a gear reduction at the problem. It naturally slows your arm down a lot more so you are less reliant on software to control it. Plus depending on your configuration, you can probably self-right your robot. I mean, adding a spring can only help an arm, but if you gear like 330 it's not mandatory.
__________________
Mentor / Drive Coach: 228 (2016-?)
...2016 Waterbury SFs (with 3314, 3719), RIDE #2 Seed / Winners (with 1058, 6153), Carver QFs (with 503, 359, 4607)
Mentor / Consultant Person: 2170 (2017-?)
---
College Mentor: 2791 (2010-2015)
...2015 TVR Motorola Quality, FLR GM Industrial Design
...2014 FLR Motorola Quality / SFs (with 341, 4930)
...2013 BAE Motorola Quality, WPI Regional #1 Seed / Delphi Excellence in Engineering / Finalists (with 20, 3182)
...2012 BAE Imagery / Finalists (with 1519, 885), CT Xerox Creativity / SFs (with 2168, 118)
Student: 1714 (2009) - 2009 Minnesota 10,000 Lakes Regional Winners (with 2826, 2470)
2791 Build Season Photo Gallery - Look here for mechanism photos My Robotics Blog (Updated April 11 2014)