A step is applied to a first-order process at t = 0. The output starts at 0 and settles at 4. At t = 2 s it reads 1.2. Find the time constant τ.
Step response worksheet with answers
A first-order system G(s) = 1/(0.2s + 1) receives a step input of size 5 at t = 0, starting from rest. How long does the output take to reach 50 % of its final value? Find t.
A system has the transfer function G(s) = 76/(s² + 3s + 76) and receives a unit step input. The poles are s = σ ± jωd. Find the real part σ.
A system has the transfer function G(s) = 21/(s² + 8s + 42) and receives a unit step input. Find the percent overshoot %OS of the step response.
A unity negative feedback loop has G(s) = 240/(s(s + 8)). Find the 2 % settling time ts of the closed-loop step response, using ts ≈ 4/(ζωₙ).
A unity negative feedback loop has G(s) = 155/(s(s + 6)). Find the 2 % settling time ts of the closed-loop step response, using ts ≈ 4/(ζωₙ).
Answer key
- 1. τ = 5.607 s
- 2. t = 0.1386 s
- 3. σ = −1.5
- 4. %OS = 8.505 %
- 5. ts = 1 s
- 6. ts = 1.333 s
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