Q4Control System
Question
2 marks
Q.4. What is meant by steady state error?
Answer
Steady state error is the difference between the reference input and the actual output as time approaches infinity, i.e. ess = lim(t→∞)[r(t)-c(t)], reflecting the system's inherent tracking inaccuracy after all transients have decayed.
Steady state error ess is defined as the value that the error signal e(t) = r(t) - c(t) settles to as time t tends to infinity, once all transient components of the response have decayed to zero. It is computed conveniently using the final value theorem applied to the error transform: ess = lim(s→0) s·E(s), and depends on the system type (number of poles at the origin of the open-loop transfer function) and the type of input applied (step, ramp, or parabolic).