-
The unit -step response of a unity feedback system with open loop transfer function
G(s) = K is shown in the figure below. (s + 1)(s + 2) 
The value of K is
-
- 0.5
- 2
- 4
- 6
Correct Option: D
| Given : G(s) = | ||
| (s + 1)(s + 2) |
From curve, steady state error = 1 – 0.75 = 0.25
| ∴ E(s) = | = | ||||
| s | |||||
| 1 + H(s)G(s) | 1 + 1. | × 1 | |||
| (s + 1)(s + 2) | |||||
| ⇒ | = 0.25 | ||||
| 1 + | |||||
| 2 | |||||
| ⇒ 1 = 0.25 + | ||
| 2 |
| ⇒ k = | = 6 | |
| 0.25 |
