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Unread 30-01-2013, 08:47
Cal578 Cal578 is offline
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Re: Velocity PID Programming: Terms dependent on time

Quote:
Originally Posted by z_beeblebrox View Post
...If it is not constant, the I and D gains are divided by the loop time.
I believe the Integral value would be multiplied, not divided. The longer the time interval, the bigger the integral. The Derivative term, as you said, is divided, because a longer time interval means a lower derivative (less slope).

Quote:
Originally Posted by Tom Line View Post
...What the heck is the integral term in a position PID anyway? How do you integrate position?
You're not integrating position, you're integrating the error of the position. So when the system actually achieves the set position, the error becomes zero, and the Integral term stops changing. That's the great thing that Integral adds (compared to just Proportional). Without it, the system always needs to have some error, otherwise the output goes to zero.
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