-
For a unit step input, a system with forward path transfer function G(s) = 20/s2 and feedback path transfer function H(s) = (s + 5) has a steady state output of—
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- 20
- 5
- 0.2
- zero
- 20
Correct Option: D
Steady state error, ess = s →∞Lim s E (s)
Given
| G(s) = | |
| s2 |
H(s) = s + 5
r(t) = 1, then R (s) = 1/s
we know that
| = | ||
| R(s) | 1 + G(s) H(s) |
| = | = | |||
| R(s) | 1 + 20/s2(s + 5) | 1/s2 + 20(s + 5) |
or
| E(s) = R(s) | |
| s2 + 20(s + 5) |
| E(s) = | . | ||
| s | s2 + 20(s + 5) |
so,
| s →∞Lim s· | |
| s2 + 20(s + 5) |
| = s →∞Lim s· | |
| 1 + 20/s + 5/s2 |
ess = 0 (apply the limit)
