what is the difference between a PI and a PD controller? In which instance or for what kind of sensor(s)would you use one as opposed to the other?
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1 Answer
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PI - Proportional - Integral
The output is a combination of how far you are from the goal and the integral of your distance from the goal (total error over time). This means that it will track small changes well but in the event of a large change it will be prone to overshooting. Good for systems which are inherently heavily damped.
PD - Proportional - Differential
The output is a combination of how far you are from the goal and how fast you are moving towards the goal. The differential part is normally negative, this means that if you are rapidly approaching the goal then you start to slow down. It handles large changes well with minimal overshoot but isn't great for tracking small changes or errors. Good for systems which inherently have a lot of momentum.
And the third option is PID which is a little more complex since it has 3 parameters rather than 2 but provides the best of both systems.
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$\begingroup$ Any idea on sensor used in PI and PD controlled system? $\endgroup$ Nov 29, 2016 at 15:55
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$\begingroup$ Differentiation of a measured signal amplifies measurement noise, so PID/PD controllers typically need sensors with low noise and proper noise filters. Integration is not a noise-sensitive operation, but PI controllers usually also benefit from noise filters due to the proportional term, but noise is generally less of an issue than for differentiating controllers. $\endgroup$ Sep 21, 2022 at 6:35