The Ziegler–Nichols tuning method is a heuristic method of tuning a PID controller

PID controller

A proportional–integral–derivative controller is a generic control loop feedback mechanism widely used in industrial control systems – a PID is the most commonly used feedback controller. A PID controller calculates an "error" value as the difference between a measured process variable and a...

. It was developed by John G. Ziegler and Nathaniel B. Nichols

Nathaniel B. Nichols

Nathaniel B. Nichols was an American control engineer who made significant contributions to the field of control theory. He is well-known for his book Theory of Servomechanism, one of the most widely read books in control engineering....

. It is performed by setting the I (integral) and D (derivative) gains to zero. The "P" (proportional) gain, is then increased (from zero) until it reaches the ultimate gain , at which the output of the control loop oscillates with a constant amplitude. and the oscillation period are used to set the P, I, and D gains depending on the type of controller used:

Ziegler–Nichols method
Control Type
P		-	-
PI			-
classic PID
Pessen Integral Rule
some overshoot
no overshoot

Evaluation

Z–N tuning creates a "quarter wave decay". This is an acceptable result for some purposes, but not optimal for all applications.

• "The Ziegler-Nichols tuning rule is meant to give PID loops best disturbance rejection performance. This setting typically does not give very good command tracking performance."

Z–N yields an aggressive gain and overshoot

Overshoot (signal)

In signal processing, control theory, electronics, and mathematics, overshoot is when a signal or function exceeds its target. It arises especially in the step response of bandlimited systems such as low-pass filters...

– some applications wish to instead minimize or eliminate overshoot, and for these Z–N is inappropriate.

External links

• http://controls.engin.umich.edu/wiki/index.php/PIDTuningClassical#Ziegler-Nichols_Method