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PID Tuning: The Ziegler Nichols Method Explained
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PID Tuning: The Ziegler Nichols Method Explained

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In this video, the Ziegler Nichols methods of tuning a PID controller are explained. The values of KP (proportional gain), KI (integral gain), and KD (derivative gain) are determined to achieve a well-tuned system.

Method 1: Proportional-Integral-Derivative (PID) Controller Tuning

  • The system is represented by KP(1 + 1/kis + KDs) with feedback.
  • To tune the system, apply a unit step input and observe the response.
  • Determine the inflection point on the response curve, which is crucial for determining the tuning values.
  • Draw a tangent line to the inflection point and measure two distances:
  • L: Distance from the origin to the tangent line.
  • T: Distance from steady state intersect to the tangent line.
  • Use these values to create a table for proportional, integral, and derivative controllers:
  • KP = 0.9T/L
  • KI = 1.2T/L
  • KD = L/0.3
  • KI/D = 2L
  • KP/KD = 0.5

Method 2: Critical Gain Method

  • Simplify the system by setting ki to infinity and KD to zero.
  • Increase KP until sustained oscillations occur, indicating marginal stability.
  • Identify Kcrit as the critical gain at which oscillations start.
  • Use Kcrit to determine tuning values in a table:
  • P controller: KP = 0.5Kcrit
  • PI controller: KI = infinity, KD = zero
  • PID controller: KI/D = Kcrit/1.2, KP/KD = Kcrit/0.6

Both methods are simple and convenient for tuning PID controllers.

Video description

In this short tutorial I will take you through the two Ziegler-Nichols tuning methods. This will let you tune the derivative, proportional and integral gains on your P, PI or PID controller. Thankfully these methods are extremely simple to understand and implement.