Question

How does cascading an integral controller in the forward path of a control system affect the relative stability (RS) and the steady-state error of that system?

(a) RS and SSE are increased

(b) RS is reduced nut SSE is increased

(c) RS is increased but SSE is reduced

(d) RS and SSE are reduced

I have been asked this question during an interview.

The origin of the question is Design Considerations for Higher-Order Systems topic in section Time Response Analysis, Design Specifications and Performance Indices of Control Systems

Answer 1

Right option is (d) RS and SSE are reduced

To elaborate: Integral Controller acts like a low pass filter. It reduces the stability as well as steady state error.