View Single Post
  #9   Spotlight this post!  
Unread 20-11-2005, 10:16
KenWittlief KenWittlief is offline
.
no team
Team Role: Engineer
 
Join Date: Mar 2003
Location: Rochester, NY
Posts: 4,213
KenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond reputeKenWittlief has a reputation beyond repute
Re: Oscillating a pnuematics valve?

Quote:
Originally Posted by Don Rotolo
Team 1676 tried that last year, but we had mixed results. The feedback loop (including the valves, movement of the air, etc.) wasn't fast enough to hold a position pneumatically when faced with variable loading. The problem is that air compresses, and so changes in load made the arm move: We hung a tetra on the arm and it drooped down.
I think you missed part of the description.

you include a clutch or locking mechanism on the joint, so once the arm is in the proper location, the clutch locks, holding the arm rigid. Unless you add enough weight to the end of the arm to overpower the clutch, its not going to move

and with this approach you dont try to control the pressure in the cylinder, or to apply pressure to both ends - you use the cylinder in the normal configuration, with the little flow restrictors to slow down their movement.

The clutch is in the feedback loop, not the valves. Once the arm has moved to the right position (up or down) the clutch locks and holds it against the pnuematic pressure, and against any added weight to the end of the arm.