A step is applied to a first-order process at t = 0. The output starts at 0 and settles at 50. At t = 2 s it reads 15. Find the time constant τ.
Step response worksheet with answers
An uncharged capacitor C = 2.2 µF is charged from a 5 V step source through a resistor R = 2.2 kΩ. How long after closing the switch does the capacitor voltage reach 90 % of its final value? Find t in ms.
A system has the transfer function G(s) = 6/(s² + s + 12) and receives a unit step input. Find the damping ratio ζ.
A system has the transfer function G(s) = 8/(s² + s + 4) and receives a unit step input. The poles are s = σ ± jωd. Find the real part σ.
A unity negative feedback loop has G(s) = K/(s(s + 10)). Find the gain K that gives a step response with 15 % overshoot.
A unity negative feedback loop has G(s) = 250/(s(s + 5)). 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 = 11.14 ms
- 3. ζ = 0.1443
- 4. σ = −0.5
- 5. K = 93.56
- 6. ts = 1.6 s
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