controling extension on piston

[tseres]

Originally Posted by 1075guy

Take a look at 1075's 2007 arm. If you can find any photos from Greater Toronto Regional, from Toronto, Canada, or Kettering Kickoff offseason event, from Flint, MI, OR an event that happened in october/november in New Jersey (sorry, I dont remember its name)

We used an elaborate system of valves to gain much control over our airflow. We controlled the feed side, as well as the exhaust side, and used some fancy code to switch them quickly in such a fashion that avoided any 'drifting' phenomena as well as any oscillations. We had just a few buttons that would send it to preset positions. 'Top' for the top spider on the rack 'Middle', 'Bottom', etc. The judges thought it was cool enough to give us the Rockwell Automation Innovation in Control award. Of course, the system came with its share of problems too. We had a manual override joystick to override the presets if we so desired, however, if the trim got nudged, it caused the arm to act extremely unpredictably, and until we learned what caused the problem, it was difficult to diagnose. Also, the potentiometer we used for position feedback was prone to... problems.

We used a similar prototype in the 2004 offseason after discovering our worm gear driven arm was hopeless, we replaced with a primitive version of our 07 arm, and it drove us to the win at the 2004 Canada's Wonderland Invitational.

I'm sure you can expect to see another pneumatic multi-position arm out of us in the future, maybe not for 2008 though.

were you the team with that really huge long piston? i just remember seeing one that looked like 3 feet tall......

(i was there and at waterloo, too, team 1565)

[Racer26]

Originally Posted by tseres

were you the team with that really huge long piston? i just remember seeing one that looked like 3 feet tall......

(i was there and at waterloo, too, team 1565)

Our ram was about a 10" stroke. 1.5" bore. We had nice black carpet ramps at GTR... we took them off for Kettering and NewJersey because they were heavy and ineffective. We also added a braking mechanism to it in the offseason to further dampen any oscillations. basically a piece of aluminum angle passing through aluminum square tube with a ram to pin it.

[JesseK]

If you don't care about accuracy and this isn't for autonomous, you can try a Pilot Operated Check Valve. Came in the 2001 KOP, saw some on mcmaster a few moons ago.

[nickcvet89]

We had great success with using the optional magnet they give with the pistons, this is good if you have a piston that is a little to long for the job.