Question

A particular control system yielded a steady state error of 0.20 for unit step input. A unit integrator is cascaded to this system and unit ramp input is applied to this modified system. What is the value of steady-state error for this modified system?

(a) 0.10

(b) 0.15

(c) 0.20

(d) 0.25

This question was addressed to me in quiz.

My question is from Steady-state Errors and Error Constants topic in portion Time Response Analysis, Design Specifications and Performance Indices of Control Systems

Answer 1

Right answer is (d) 0.25

To explain: The integrator is similar to the phase lag systems and it is used to reduce or eleminate the steady state error and when it is cascaded with the ramp input hence the acceleration error constant is calculated which is equal to 0.25.