A step is applied to a first-order process at t = 0. The output starts at 0 and settles at 100. At t = 5 s it reads 40. Find the time constant τ.
Step response worksheet with answers
An uncharged capacitor C = 47 µF is charged from a 9 V step source through a resistor R = 10 kΩ. Find the 10–90 % rise time tr of the capacitor voltage, in ms.
A system has the transfer function G(s) = 37/(s² + 3s + 37) 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) = 37.5/(s² + 13s + 75) and receives a unit step input. Find the 2 % settling time ts of the step response, using ts ≈ 4/(ζωₙ).
A series RLC circuit with R = 57 Ω, L = 500 mH and C = 100 µF is connected to a 5 V step at t = 0. The capacitor is uncharged and no current flows before the step. Find the undamped natural frequency ωn in rad/s.
A second-order system without zeros must have a step response with 8 % overshoot. Find the damping ratio ζ.
Answer key
- 1. τ = 9.788 s
- 2. tr = 1033 ms
- 3. σ = −1.5
- 4. ts = 0.6154 s
- 5. ωn = 141.4 rad/s
- 6. ζ = 0.6266
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