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7.6.2
Setting Loop Gains Using the Ziegler and Nichols Tuning
Approach
This approach provides good response to system disturbances with gains producing an amplitude
ratio of 1/4. The amplitude ratio is the ratio of the second peak over the first peak in the closed loop
response.
1. Determine the three process model parameters, K, T
gains.
2. Calculate the Reaction rate:
R = K/T
3. For Proportional control only, calculate Kp as:
Kp = 1/(R * T
For Proportional and Integral control, use:
Kp = 0.9/(R * T
For Proportional, Integral and Derivative control, use:
Kp = G/(R * T
Ki = 0.5 * Kp/T
Kd = 0.5 * Kp * T
4. Check that the Sample Period is in the range
(T
+ T
p
c
GFK-2950C
c
) = T
/(K * T
)
p
c
p
) = 0.9 * T
/(K * T
p
c
) where G is from 1.2 to 2.0
p
p
p
)/10 to (T
+ T
)/1000
p
c
February 2018
Chapter 7. PID Built-In Function Block
and T
for use in estimating initial PID loop
p
c
) Ki = 0.3 * Kp/T
p
p
361
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