Page 194 - MATLAB an introduction with applications

Control Systems ——— 179

 y 1   10   x 1 
  =    
 y 2  01   x 2
Plot the four sets of Bode diagrams f or the system [two for input1, and two for input 2] using MATLAB.

Solution: There are 4 sets of Bode diagrams (2 for input1 and 2 for input 2)
>> % Bode Diagrams

>> A=[0 1;-25 -9];
>> B=[1 1;0 1];
>> C=[1 0;0 1];
>> D=[0 0;0 0];
>> bode(A,B,C,D)
Bode Diagram
From: In(1) From: In(2)
0
Out(1) –50

To:
–100
0
(deg) Out(1) –45
Phase To: –135
–90
(dB); 100

Magnitude Out(2) To: 0

–100
180
Out(2) 0

To:
–180
0 2 0 2
10 10 10 10
Frequency (rad/sec)
Fig. E3.27 Bode diagrams
Example E3.28: Draw a Nyquist plot for a system defined by
 x   0 1   x   0 
1
1
+
  =       u
  x 2    − 25 5    x 2    20 

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