#### curious_mind

##### Member level 5

1. When do we choose time domain or frequency domain method to design a control system?

2. I see that bode plot is sufficient in most cases to assess stability, then what is the role of routh hurwitz, nyquist and polar plot?

3. Can root loci be used when multiple parameters are variable (not just gain)?

4. Does State space directly models the differential equation without any transformation (i guess to preserve the initial states) and where does the general form of state equations come from? (books do not provide the basis)

5. Difference between compensator (lead,lag) vs PID controller (no clarity is provided anywhere)

6. Can I have only I controller without P and D?

7. For design based on state space methods, what are the ways to check stability. (is bode plot,nyquist,routh hurwitz or root loci applicable)?