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Unread 31-01-2011, 15:01
de_ de_ is offline
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AKA: Dave Edwards
FRC #1310 (Runnymede Robotics)
Team Role: Mentor
 
Join Date: Apr 2005
Rookie Year: 2005
Location: Toronto, Ontario
Posts: 256
de_ is a jewel in the roughde_ is a jewel in the roughde_ is a jewel in the roughde_ is a jewel in the rough
Any PID experts ?

In the ideal world, we would like to make use of the PID Class to move our (encoder sensored) tube lifter up and down 2 stage ladder as follows

- move to a specified height accurately and stay there (and hopefully not burn a motor out trying to hold it).

- move at a specified max speed (which may be less than the physical max speed) to that height slowing down as it approaches as opposed to a hard stop.

- be able to handle the completely different dynamics of lifting upward against gravity versus coming down with gravity (without excess speed).
Not quite certain how to avoid gravity / momentum based overshoot at the bottom leading to a major impact.

Is this possible within the current PID classes ? Any suggestions ?