Why are we still teaching Routh-Hurwitz criterion in Control

[Mohamed_Wael]

I am a TA for Automatic control class, I can't find an answer for my students about why we are still studying Routh-Hurwitz criterion as almost anyone can use computer software to find the roots of the closed-loop system and determine stability instead of doing these tedious hand calculations

 

[rude man]

Learning Routh-Hurwitz never made much sense to begin with since it presupposes an explicit transfer function which in many cases is unavailable, with only empirical data to analyze.

Bode gain and phase plots almost always suffice, are easy to derive and plot, and allow expeditious system synthesis.

For the ultimate in stability analysis the Nyquist criterion is superior to all others as it handles all cases. Root-locus is also still fine but maybe harder to assimilate.

Bottom line: settle for Bode plots and Nyquist.