Page 165 - MATLAB an introduction with applications

150 ——— MATLAB: An Introduction with Applications

Example E3.10: A PID controller is given by

(s + 0.57) 2
( ) =
Gs 29.125
c
s
Draw a Bode diagram of the controller using MATLAB.
Solution:
2
29.125(s + 1.14s + 0.3249)
() =
Gs
c
s
2
29.125s + 33.2025s + 9.4627
=
s
The following MATLAB program produces the Bode diagram
>> % MATLAB Program
>> % Bode diagram
>> num= [29.125 33.2025 9.4627];
>> den= [0 1 0];
>> bode (num, den)
>> title (‘Bode diagram of G(s)’)

Bode Diagram
50
(dB) 45
Magnitude 40

35

30
90
(deg) 45

Phase 0
–45
–90
–1 0 1
10 10 10
Frequency (rad/sec)
Fig. E3.10 Bode diagram of G(s)

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