Quote:
Originally Posted by GeeTwo
Don't use pneumatic pistons for something that needs to stop at various points along its travel. It's possible, but you could work weeks getting it right the first time. Don't use a motor to hold something in place; motors are designed to spend most of their time running fast at fairly low torque. Figure out how much current you'll draw with each motor and other device to make sure you won't trip that breaker, or the main at 120A. The standard compressor is designed for a 7% duty cycle - if you're running it much more than that, find another compressor with the same cfm rating, but a higher duty cycle.
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I agree with almost everything you said except for the pneumatics.
We've had good luck with pneumatic pistons that need to stop at locations other than the ends. In our 2005 robot we had an arm that was raised and lowered to various heights by a single huge pneumatic cylinder, and it took no special programming or driver practice to control. We were also happy using an intermediate location to aim our 2013 robot. I think they're easier to write software for than a motor because they don't burn out when you tell them to do the wrong thing.
Also, I think most teams can safely ignore the pump duty cycle ratings. Matches are short.