Linear motion setup

[DonRotolo]

Originally Posted by 1075guy

Go 8.5" forwards at a speed of 1"/sec
Go 4.5" backwards at a speed of 10"/sec
Go 1" forwards at a speed of 100"/sec
Go 5" backwards at a speed of 50"/sec

Forget pneumatics, they would not work as you expect for this kind of application.

An alternative if the load is light enough - say a magic marker - is to use a stepper with some Gates toothed belt and sprockets. That could be made to work pretty darned fast with a decent stepper. 0.1-0.5" is not a problem with either a lead screw or belt drive.

[Racer26]

Don, with all due respect, given my past experience in FRC with using pneumatics in non-standard configurations to achieve an innovative solution to a problem, I'm not convinced that they couldn't be used like this, however, I do agree that it would be much more complex than using a stepper motor with leadscrew or belted drive or similar.

[Racer26]

What about something like the 23L2 motor from this page: http://www.anaheimautomation.com/pro...75&pt=t&cID=19

connected to a leadscrew setup, driven by this driver chip: http://www.sparkfun.com/products/10735

Assuming the stepping + leadscrew combination could create fast enough motion with enough torque/thrust, it seems to put the price point in the right ballpark.

[DonRotolo]

Originally Posted by 1075guy

Don, with all due respect, given my past experience in FRC with using pneumatics in non-standard configurations to achieve an innovative solution to a problem, I'm not convinced that they couldn't be used like this, however, I do agree that it would be much more complex than using a stepper motor with leadscrew or belted drive or similar.

I think we're saying the same thing. Yes, of course it's possible. In fact, if the endpoints were fixed, pneumatics make it trivial and would be the better choice. But variable endpoints in both directions, with variable speed, make it far too complex to consider (IMHO).

...And if #23 steppers aren't strong enough, they come in several larger sizes.

[Racer26]

New question for everybody (I think I've decided to go with a NEMA 34 stepper as the powerplant for this operation).

Does anybody know of a stepper driver chip capable of handling 5-10A of current? Something that I feed enable/step/direction lines to, and hook up the 4 (or 8) wires of my stepper motor to? A higher current version of this chip: http://www.allegromicro.com/en/Produ..._Numbers/3977/

Bonus points if it can handle more than 35V too (as high as 70 or even 90 VDC would be good)