Question 11.8.14: By applying MATLAB, perform the Bode and Nyquist plots in th......
By applying MATLAB, perform the Bode and Nyquist plots in the complex plane of the thirdorder system whose transfer function is given by
G(s)H(s)=K G_{o}(s)={\frac{K}{s^{3}}}
The input to and output from MATLAB are included in Program Listing 11.14 and Figure 11E14.
Script File
Program Listing 11.14
>> num = [0 0 0 1];
>> den = [1 0 0 0];
>> bode(num,den)
>> title(‘Bode Plot of a Third Order System’)
>> nyquist(num,den)
>> title(‘Nyquist Plot of a Third Order System’)
Before considering the next example, it may be appropriate to observe that the Bode plots in Figures 11E13a and 11E14a are consistent with the theory. For example, in Figure 11E14a the magnitude plot gives a negative gradient of 60 dB per decade. However, the Nyquist plots in Figures 11E13b and 11E14b do not reveal any observable meaning. Computational experiments with MATLAB by increasing and decreasing the ranges of both the real and imaginary axes were unable to provide any meaningful information. This reflects the fact that there are limitations to employing MATLAB for the construction of Nyquist plots
