Quote:
Originally Posted by JVN
First time in FIRST? Maybe...
However, no offense to Steve -- this is just an example of a grounded link, or as some people might call them a "virtual 4-bar" linkage. It is pretty darn cool, but this technology has been around for a long time.
One of my hobbies is researching cool mechanisms and linkages from history. Back in "the day" when computer control was non-existent, engineers designed machines which turn constant rotary motion (from a stem engine, or water wheel, or whatever) into all sorts of different motions -- including linear motion.
In fact, I know a company in NY involved in a design which utilized something similar to this for an oscillating shower-head on a paper machine.
Call it the Forbes arm if you want, but to me this is similar to the people who used to say Paul Copioli invented the 4-bar linkage...
Again -- no offense intended to Steve Forbes on a beautiful design.
I love it when someone takes a cool linkage or mechanism and uses it with great success on an FRC robot. Now if only I can find an excuse for a Geneva Mechanism (I keep trying to find one).
-John
|
John, no offense taken at all. I'm fully aware of the linkage concepts involved and know they're nothing new. When we had it modeled up in solidworks we were talking about how we had never seen an arm mechanism with this geometry used before on a FIRST bot... the name was jokingly suggested by another team member. Seeing that it was already implemented by 1595 in 07 shows that we're not actually the first to use it, which comes as no surprise.
I'm also fascinated with linkages and rotational/linear power conversion systems (Selectric typewriter, anyone?). This mechanism actually came from a somewhat structured problem solving approach. Sometime on Saturday (kickoff) night I sketched something like this on a piece of paper:
...with the thought that the ideal* arm would be a single DOF mechanism that followed that path. Floor to top peg, passing through initial starting position. After that it was easier to narrow the motion down to possible mechanisms. Form follows function!
Quote:
Originally Posted by ajlapp
These are definitely cool mechanisms....
To echo John's comments, this mechanisms has been deployed before.
Team RUSH used the same system in 1997 for the very first inner tube game.
I can't find a picture right now.  We call it a passive arm. |
Sounds like it was first implemented ages ago, I'd love to see a photo if you happen to find one!
*no such thing in this competition, but you know what I mean