A step is applied to a first-order process at t = 0. The output starts at 0 and settles at 20. At t = 3 s it reads 18. Find the time constant τ.
Step response worksheet with answers
An uncharged capacitor C = 1 µF is charged from a 5 V step source through a resistor R = 4.7 kΩ. Find the capacitor voltage vC at t = 2.35 ms.
A system has the transfer function G(s) = 60/(s² + 11s + 60) and receives a unit step input. Find the natural frequency ωn in rad/s.
A system has the transfer function G(s) = 28.5/(s² + 6s + 57) and receives a unit step input. The poles are s = σ ± jωd. Find the real part σ.
A mass m = 10 kg hangs on a spring k = 200 N/m with a viscous damper c = 36 N·s/m (m·x″ + c·x′ + k·x = F). At rest in equilibrium, a constant force F = 50 N is suddenly applied. Find the time tp at which the displacement is largest.
A unity negative feedback loop has G(s) = K/(s(s + 8)). Find the gain K that gives a step response with 2 % overshoot.
Answer key
- 1. τ = 1.303 s
- 2. vC = 1.967 V
- 3. ωn = 7.746 rad/s
- 4. σ = −3
- 5. tp = 0.7674 s
- 6. K = 26.32
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