UFMFYJ-153
Control Engineering
Chapter 7: Tutorial Sheet Bode Plots
1) A system has an open loop transfer function
Construct the system Bode amplitude and phase plots using asymptotic
(straight line ) approximations
2) Shown in the table are the data from an open-loop frequency response test on
some plant. Estimate the transfer function of the plant.
Frequency
Rad/s
Amplitude ratio
(dB)
Phase shift
degrees
1.0
14
-14
2.2
13
-29
4.6
11
-55
10
6
-90
21
-2
-124
46
-13
-150
100
-26
-165
215
-39
-173
464
-53
-176
1000
-66
-178
3) In a test on a servomechanism, the following open loop response data were
obtained:
Frequency
rad/s
0.05
0.1
0.3
0.5
1
2
3
5
10
20
Gain (dB)
36
30
21
17
10
0
-8
-20
-39
-57
Phase lag
(degrees)
94
98
110
120
145
186
208
230
250
260
Plot the frequency response plots as:
a) Bode amplitude and phase plots and
b) A Nyquist diagram
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