PID Controller with Different Tightness

BESTune allows users to specify different tightness when tuning their PID controllers. Here is an example. Using the CO and PV measurements that come with the BESTune package, we can get different PID controllers with different tightness, see below.

A. Tightness=100 (see below). In this case:

  1. PV tracks SP quickly and with no oscillations.
  2. CO is very sensitive to the control error E=SP-PV.
  3. The peak value of CO is close to 228.

B. Tightness=30 (see below). In this case:

  1. PV tracks SP at a slower speed and with no oscillations.
  2. CO is not so sensitive to the control error E=SP-PV.
  3. The peak value of CO is close to 129.

C. Tightness=5 (see below). In this case:

  1. PV tracks SP at a very low speed and with no oscillations.
  2. CO is not sensitive to the control error E=SP-PV.
  3. The peak value of CO is about 75. And BESTune suggests that the D term is not needed.

D. Tightness=1 (see below). In this case:

  1. PV tracks SP at the slowest speed of the four case presented here and with no oscillations.
  2. CO is very sluggish in response to the control error E=SP-PV.
  3. There is no jump in CO. And BESTune suggests that the D term is not needed.

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