1.First of all

・ I created this page when I received a comment on the qiita page (https://qiita.com/sato235/items/f991411074c578d1640c) that I wrote last time that it would be interesting to output a waveform graph and consider it.

2. Reference

2.1. Books

[1] Hiroki Minami, Ohmsha, "Introduction to Control Engineering with Python"

2.2. Web page

a) Author support page of [1], https://y373.sakura.ne.jp/minami/pyctrl b) Last self-page, https://qiita.com/sato235/items/f991411074c578d1640c c) Graphing function of matlab function of control module, http://matsulib.hatenablog.jp/entry/2013/04/27/093008

3. Transfer function and graphing

First, import the module.

import sympy
from control import matlab
import numpy as np
import matplotlib.pyplot as plt

Create transfer function

Np = [0,1]
Dp = [1,2,3]
P = matlab.tf(Np, Dp)
print(P)

Transfer function output

      1
-------------
s^2 + 2 s + 3

When a step function is input to the above transfer function.

t = np.linspace(0, 3, 1000)
yout, T = matlab.step(P, t)
plt.plot(T, yout,label="test")
plt.axhline(1, color="b", linestyle="--")
plt.legend(bbox_to_anchor=(1, 0.25), loc='upper right', borderaxespad=0, fontsize=11)

When an impulse response function is input to the transfer function P.

yout, T = matlab.impulse(P, t)
plt.plot(T, yout,label="test")
plt.axhline(0, color="b", linestyle="--")
plt.xlim(0, 3)
plt.legend(bbox_to_anchor=(1, 1), loc='upper right', borderaxespad=0, fontsize=11)

4. Conclusion

-I learned that the control module has a matlab calculation function. -Similarly, there was also a drawing function of matplotlib. ・ Next, I would like to consider the results obtained by changing the input function.