A first-order system G(s) = 0.5/(2.5s + 1) receives a step input of size 20 at t = 0, starting from rest. Find the output y(5) at t = 5 s.
Step response worksheet with answers
1.Easy
G(s) = 0.5/(2.5s + 1)U = 20t = 5 s
y(5) =
2.Easy
A first-order system G(s) = 10/(2.5s + 1) receives a step input of size 2 at t = 0, starting from rest. Find the output y(1.25) at t = 1.25 s.
G(s) = 10/(2.5s + 1)U = 2t = 1.25 s
y(1.25) =
3.Medium
A system has the transfer function G(s) = 18/(s² + 5s + 18) and receives a unit step input. Find the percent overshoot %OS of the step response.
G(s) = 18/(s² + 5s + 18)
%OS = %
4.Medium
A system has the transfer function G(s) = 60/(s² + 4s + 60) and receives a unit step input. Find the percent overshoot %OS of the step response.
G(s) = 60/(s² + 4s + 60)
%OS = %
5.Hard
A unity negative feedback loop has G(s) = 105/(s(s + 16)). Find the 2 % settling time ts of the closed-loop step response, using ts ≈ 4/(ζωₙ).
G(s) = 105/(s(s + 16))
ts = s
6.Hard
A second-order system without zeros must have a step response with 50 % overshoot. Find the damping ratio ζ.
%OS = 50 %
ζ =
Answer key
- 1. y(5) = 8.647
- 2. y(1.25) = 7.869
- 3. %OS = 10.11 %
- 4. %OS = 43.19 %
- 5. ts = 0.5 s
- 6. ζ = 0.2155
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