A step is applied to a first-order process at t = 0. The output starts at 0 and settles at 20. At t = 0.5 s it reads 8. Find the time constant τ.
Step response worksheet with answers
1.Easy
y(∞) = 20y(0.5) = 8
τ = s
2.Easy
A first-order system G(s) = 8/(s + 4) receives a step input of size 20 at t = 0, starting from rest. Find the final value y(∞) of the output.
G(s) = 8/(s + 4)U = 20
y(∞) =
3.Medium
A system has the transfer function G(s) = 146/(s² + 13s + 73) and receives a unit step input. Find the peak time tp of the step response.
G(s) = 146/(s² + 13s + 73)
tp = s
4.Medium
A system has the transfer function G(s) = 48/(s² + 10s + 48) and receives a unit step input. Find the natural frequency ωn in rad/s.
G(s) = 48/(s² + 10s + 48)
ωn = rad/s
5.Hard
A unity negative feedback loop has G(s) = K/(s(s + 6)). Find the gain K that gives a step response with 10 % overshoot.
G(s) = K/(s(s + 6))%OS = 10 %
K =
6.Hard
A second-order system without zeros must have a step response with 8 % overshoot. Find the damping ratio ζ.
%OS = 8 %
ζ =
Answer key
- 1. τ = 0.9788 s
- 2. y(∞) = 40
- 3. tp = 0.5665 s
- 4. ωn = 6.928 rad/s
- 5. K = 25.75
- 6. ζ = 0.6266
Full step-by-step solutions: practise this topic on examproblems.com.