# Electronics and Communication Engineering - Automatic Control Systems - Discussion

Discussion Forum : Automatic Control Systems - Section 1 (Q.No. 26)
26.
Consider the systems with following open loop transfer functions
1. 2. 3. If unity feedback is used, the increasing order of time taken for unit step response to settle is
1, 2, 3
3, 1, 2
2, 3, 1
3, 2, 1
Explanation: . For the three systems the values of ξωn are 1.8, 2.5 and 2 respectively.

Hence values of T are 0.55, 0.4 and 0.5 respectively.

Discussion:
3 comments Page 1 of 1.

Anish kumar said:   8 years ago
See.

100/s(s+5) open loop transfer function.

100/s(s+5)/(1+100/s(s+5) ) = 100/s2+5s+100.

So coefficient of s = 2*si*wn = 5.
= si*wn=2.5.

Settling time = 4/2.5 = 1.6.

Likewise for 1 t settling will be 2.2, for 2 t settling will be 1.6, and for 3 t settling will be 2.

So(1) = 2.2.
(2) = 1.6.
(3) = 2.5.

So increasing order will be 2, 3, 1.

Arslan said:   8 years ago
@Hina khan.

Kindly explain it again. I did not understand.

Hina khan said:   9 years ago
Settling time will be 4T so increasing order of Ts will be 2, 3, 1.