0
2.1kviews
Figure shows the unit step response of a second order system. Determine the following from the plot

(i) Gain

(ii) Damping ratio

(iii) Natural Frequency

(iv) Transfer function

enter image description here

1 Answer
0
53views

From the given figure,

Mp=3.45-2

=1.45

tp=0.55 sec

ts=6 sec

Mp=eπξ2(1ξ22))

1.45=eπξ2(1ξ22)

Log 1.45=πξ(1ξ2) log e

0.161=πξ(1ξ2) x 0.4342

0.3707=πξ(1ξ2)

0.118=ξ(1ξ2

Squaring both the sides

0.0139=ξ2(1ξ2)

0.0139-0.0139ξ2=ξ2

1.0139ξ2=0.0139 ξ= 0.117

Peak time,tp=0.55 sec=πwd

wd =5.70 rad/sec

wd=wn(1ξ2)

wn=5.70(15.702)

wn=5.789 rad/sec

wn->Natural frequency

T.F=(w2n)(S2+2ξwnS+w2n)

T.F= 32.94(S2+1.342S+32.94)

Gain of system=1(1+G(S)H(S))

=11+32.94(S2+1.342S+32.94)x1)

Gain of system=(S2+1.342S+32.94)(S2+1.342S+65.88)

Please log in to add an answer.