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PID By Tycho

Task: What is PID?

PID is useful in many ways, such as setting an arm to a certain position, going straight based on a gyro or following a line. There are three parts to a PID control program : Proportional, Integral and Derivative.

Proportional: How much error is there? The proportional part of PID is useful because it tells you how far away you are from your target value, so you know how fast you should go to correct it.

Integral : What is the total error over time? The integral part of PID is useful in some cricumstances, but is not always a good thing to have all the time. One would use integral to tell whether you're stuck on a physichal barrier, so you can try to overcome it by increasing the power. A "leaky" integral is one that slowly returns back to zero, so you stop correcting for a barrier that might have been overcome already.

Derivative : How fast is the error changing? The derivative part of PID help measures how fast your error is going to or from your target. One would use derivative to slow down the motors when approaching the target in order to prevent from overshooting.

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Written on February 6, 2015