pic: 488 Arm Prototype

[Madison]

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[Bleric]

Wow, that looks really good.

You may be interested in this:

http://www.chiefdelphi.com/forums/sh...ad.php?t=23934

[Stephen Kowski]

you mention that the 24" is an air hog, but it may help if you put one of the regulators in front of it and run it at 20 psi (which i believe lifts 50 lbs but im not sure).....we used it last year at 60 and wow you are dead on that it is an air hog, but this year I imagine you aren't lifting the robot in the air just some tetras.....good luck

[Spikey]

It looks like a lot of teams will be using the big pneumatic cylinders this year. It will be interesting to see how well people manage their air.

[M. Hicken]

im sure im going to get chewed on for this, but there are the students?

BTW, the arm looks good. and yeah, the 24" is a big air hog, 3 years ago we had 2 of them. Needless to say we didnt do well, in fact, i dont think we ever used them both.

[Cory]

Originally Posted by M. Hicken

im sure im going to get chewed on for this, but there are the students?

BTW, the arm looks good. and yeah, the 24" is a big air hog, 3 years ago we had 2 of them. Needless to say we didnt do well, in fact, i dont think we ever used them both.

Adults are allowed to do things... just because there's no student pictured means nothing

[Mr. Ivey]

Just to re-state the obvious... that is a whole lot of air being used... just a suggestion, to take the other side of what Stephen Kowski said about lowering the pressure. You could lower the volume of what you have to fill. P1V1=P2V2 so you can change volume or pressure. Just a suggestion if you are worried about air problems, lower the pressure to say 40psi or so, and downsize the diameter of the piston. Sacrifice a little of both, just my two cents.
ivey

[Sachiel7]

Hmm...
That looks awful familliar...

[Madison]

Originally Posted by Stephen Kowski

I imagine you aren't lifting the robot in the air just some tetras.....good luck

Two tetras at the end of a 60" moment arm exert about 100 ft./lbs. of force and that's a lot like lifting a robot, actually. If your piston pushes against the arm anywhere within 12" of the point of rotation, it's actually more work than lifting a robot.

Originally Posted by M. Hicken

im sure im going to get chewed on for this, but there are the students? (sic)

The students were probably eating lunch. Mentors don't have time for that.

Originally Posted by Mr. Ivey

Just to re-state the obvious... that is a whole lot of air being used

This was the first iteration of a prototype that has since been reworked to require less air reserves for its operation as well as shorter stroke, smaller bore pistons. Also, we tried to take advantage of the implicit binary nature of pistons and use it to our advantage rather than pursue further complicating the mechanism by trying to stop pistons in mid-stroke.

I have Inventor models of the newest iteration that are incomplete, but perhaps I'll share those sometime soon so that people might see how the design is progressing.

[Mr. Ivey]

Originally Posted by M. Krass

Also, we tried to take advantage of the implicit binary nature of pistons and use it to our advantage rather than pursue further complicating the mechanism by trying to stop pistons in mid-stroke.

Awl come one... Please try and make it harder than it needs to be. Every year people go into a multi-staging frenzy, if you really want to multi-stage, just use two shorter pistons connected to each other. Just another suggestion, but I know you have already revamped your prototype...
ivey

[Jay H 237]

Nice job with the arm.

Are you planning on using a third cylinder or a motor (or motor and gearbox combo) for the wrist movement?

[Greg Perkins]

Hey It looks really good!!

Madison, you may want to contact my team leader, Dave Kelly(not from indiana) and ask him about our regenitive pneumatic circuit davekelly@cyberportal.net is his email

Basically when you extend your arm it will move reallllllly slow as the pnuematic extends, but when its retracted, it saves air and goes much faster...

give him a note..we did it last year, and worked wonderfully

[Zanella BR]

Interesting design!

[Madison]

Originally Posted by Jay H 237

Are you planning on using a third cylinder or a motor (or motor and gearbox combo) for the wrist movement?

We are trying to design a grabbing mechanism that minimizes the need for any additional motion. If we're successful, we will be able to use the motion of the arm to grab a tetra securely and will not need further actuation. We have one idea floating about that does that superbly while picking up tetras, but doesn't let go of them so well. We have a second idea that requires actuation, but releases tetras easily and accurately.

Originally Posted by Greg Perkins

Madison, you may want to contact my team leader, Dave Kelly(not from indiana) and ask him about our regenitive pneumatic circuit davekelly@cyberportal.net is his email

Basically when you extend your arm it will move reallllllly slow as the pnuematic extends, but when its retracted, it saves air and goes much faster...

Thanks, Greg. I'll send him an e-mail today and see what more I can learn about this. I have real concern about the speed at which the pistons actuate and its effect on our center of gravity as well as how it minimizes control of the placement of tetras. This sounds like it may be a solution.

[Stephen Kowski]

Originally Posted by Mr. Ivey

downsize the diameter of the piston.

I'm sure if they could they would but they can't so they won't.....24" is only available in the 2" bore size this year which does not make much sense, but whatever....