I-PD type control

・In Japanese
＜Premise knowledge＞
・PID controller
・Scilab

■What is an I-PD type control

In PID control, when the target value changes significantly due to the derivative term or proportional term, a large change in the manipulated variable is called a kick. Here, I will explain I-PD type control, which is one of the techniques for suppressing kicks. A similar control is called PI-D type control.

Normal PID control gains according to the deviation between the target value and the actual value. On the other hand, in I-PD type control, the proportional term and differential term gain according to the actual value. A comparison of the two is as follows. Note that the proportional term and the differential term are subtractions.

■I-PD type control design

The design result in Scilab is as follows. Click here for the controlled object and the contents of the differentiator



＜Simulation result＞
The parameters are as follows. You can see that there is no kick in the proportional and derivative terms.

　Kp=2, Ki=4, Kd=0.35

＜Disadvantages of I-PD type control＞

With I-PD type control, there is no sudden change (kick) in the amount of operation, but there is a disadvantage of slow response. The following methods are used to improve responsiveness.

■Feed forward and I-PD type control

To improve responsiveness, a gain is given to the target value as follows. This is the effect of feedforward.



＜Simulation result＞
The parameters are as follows. You can see that the responsiveness is better than when there is no F/F term. However, increasing the F/F term requires retuning the PID term due to increased overshoot.

　Kf=1, Kp=2, Ki=4, Kd=0.35

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