A step is applied to a first-order process at t = 0. The output starts at 0 and settles at 50. At t = 5 s it reads 25. Find the time constant τ.
Step response worksheet with answers
A first-order system G(s) = 0.5/(2.5s + 1) receives a step input of size 5 at t = 0, starting from rest. How long does the output take to reach 99 % of its final value? Find t.
A system has the transfer function G(s) = 82/(s² + 6s + 82) and receives a unit step input. Find the peak time tp of the step response.
A system has the transfer function G(s) = 68/(s² + 4s + 34) and receives a unit step input. Find the 2 % settling time ts of the step response, using ts ≈ 4/(ζωₙ).
A mass m = 2.5 kg hangs on a spring k = 1000 N/m with a viscous damper c = 40 N·s/m (m·x″ + c·x′ + k·x = F). At rest in equilibrium, a constant force F = 25 N is suddenly applied. Find the percent overshoot %OS of the displacement.
The step response of a second-order system without zeros shows 4.3 % overshoot, and the first peak occurs at t = 0.5 s. Find the natural frequency ωn.
Answer key
- 1. τ = 7.213 s
- 2. t = 11.51 s
- 3. tp = 0.3677 s
- 4. ts = 2 s
- 5. %OS = 25.38 %
- 6. ωn = 8.893 rad/s
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