PID Control System Design and Automatic Tuning using MATLAB/Simulink. Liuping Wang

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Название PID Control System Design and Automatic Tuning using MATLAB/Simulink
Автор произведения Liuping Wang
Жанр Отраслевые издания
Серия
Издательство Отраслевые издания
Год выпуска 0
isbn 9781119469407



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PI images images PID images images images
images images images
P images
PI images images
PID images images images

      For the estimation of time delay images, images, and images when using MATLAB, it is a fairly straight forward procedure to draw the lines and pinpoint the data points. The MATLAB command for finding the point on a graph is called ginput. For example, by typing

      [a,b]=ginput(1)

      a cross hair will appear on the MATLAB figure and a double click on the point of interest will yield the exact values we need. This graphic procedure will be demonstrated in the example section (see Section 1.5).

      1.3.3 Food for Thought

      1 Can you apply Ziegler-Nichols oscillation tuning method to a first order system? Why?

      2 Can you apply the reaction curve based tuning rules to unstable systems? Why?

      3 How do we decide the sign of the proportional feedback controller gain when using the Ziegler-Nichols oscillation method?

      4 Can you envisage any potential danger when using Ziegler- Nichols oscillation method?

      5 How do you design a step response experiment?

      6 What information will the step response experiment provide?

      7 How do you determine steady-state gain, parameter and time delay from a reaction curve?

      8 What are your observations when comparing Ziegler-Nichols and Cohen-Coon tuning rules, in terms of signs and values of , and ?

      9 Is there any desired closed-loop performance specification among the tuning rules?

      This section will discuss the PID controller tuning rules that are derived based on a first order plus delay model. These tuning rules worked well in applications.

      

      1.4.1 IMC-PID Controller Tuning Rules

      The internal model control (IMC)-PID tuning rules (Rivera et al. (1986)) are proposed on the basis of a first order plus delay model:

equation

      When using the IMC-PID tuning rules, a desired closed-loop response is specified by the transfer function from the reference signal to the output:

equation

      where images is the desired time constant chosen by the user. The PI controller parameters are related to the first order plus delay model and the desired closed-loop time constant images, which are given as:

      (1.46)equation

      If the system has a second order transfer function with time delay in the following form:

equation

      then a PID controller is recommended. Assuming that images, then the PID controller parameters are calculated as