Question 11.8.4: By employing MATLAB, perform the root locus plot of the foll......
By employing MATLAB, perform the root locus plot of the following control system whose open-loop transfer function
G(s)H(s)=K G_{o}(s)={\frac{K(2s+5)(10s+7)}{(s^{2}+5s+40)(100s^{2}+3s+6)}}.
Expanding and simplifying the given open-loop transfer function, one can show that
G_{o}(s)={\frac{20s^{2}+64s+35}{100s^{4}+503s^{3}+4021s^{2}+150s+240}}
which is applied to the root locus construction.
The input to and output from MATLAB are included in Program Listing 11.4a and Figure 11E4a. As can be observed the loci near and on the real axis are too small to distinguish their features a statement is added to Program Listing 11.4a in order to provide a better view of the plot. This new program is included in Program Listing 11.4b. The output from MATLAB is presented in Figure 11E4b.
Script File
Program Listing 11.4a
>> num = [0 0 20 64 35];
>> den = [100 503 4021 150 240];
>> rlocus(num,den,‘k’)
>> title(‘Root Locus Plot of Example 4 Section 11.8’)
Program Listing 11.4b
>> num = [0 0 20 64 35];
>> den = [100 503 4021 150 240];
>> rlocus(num,den,‘k’)
>> axis([−1.5 0.5 −3 3]);
>> title(‘Root Locus Plot of Example 4 Section 11.8’)
