-
The open loop transfer function of a unity feedback control system is given by—
G (s) = K(s + 2) s(s2 + 2s + 2)
The centroid and angles of root locus asymptotes are respectively—
-
- zero and + 90°, – 90°
- – 2/3 and + 60°, – 60°
- zero and + 120°, – 120°
- – 2/3 and – 90° and – 90°, + 90°
- zero and + 90°, – 90°
Correct Option: A
Centroid
| = | ∑ realpart of the poles – ∑ realpart of zeros |
| n – m |
| = | 2 – 2 | = | 0 | = 0 |
| 3 – 1 | 2 |
Where n = no. of poles, m = no. of zeros. Angle of asymptotes
| = | (29 + 1) | × 180°, = q = 0, 1 |
| n – m |
| = | (2 × 0 + 1) 180 | , | (2 × 1 + 1) 180 |
| 3 – 1 | 3 - 1 |
= 90°, 270°
or
90°, – 90°
