Included in the ZIP file is a SIMULINK model of a 3 degree of freedom system along with the input data and appropriate gain values a, b, & c. The SIMULINK model generates both the pole/zero locations along with the corresponding BODE plots. The first 3 maps and plots I understand, but the last one I do not. I am hoping someone with extensive control system experience might elucidate what is happening.
The first map & plot pertain to the input and output of the lowest order subsystem. The 2nd pertains to the mid order system, & the 3rd pertains to the highest order system. Each of the first 3 maps show 3 pole complex pairs along with 2 complex pairs of ZEROS that correlate with the pole pairs that belong to the adjacent subsystems. For example, the 2nd map pertaining to the MID frequency subsystem shows the 3 pole pairs, and 2 ZERO pairs belonging to the LO (1st) & HI (3rd) order subsystems. Likewise, the 1st map shows ZERO pairs that belong to the 2nd & 3rd subsystem, and the 3rd map shows ZERO pairs belong to the 1st & 2nd subsystems. I hope you, the reader, can follow what I am trying to say.
The last, 4th, map shows all 3 pole pairs along with 2 ZEROS setting on the REAL axis. The input is to the 1st subsystem & the output is from the 3rd subsystem. I was expecting to only see the 3 pole pairs, and NO ZEROS. Why is this & is it possible to get a response that is not influenced by any ZEROS?
Appreciate any insight
