Glossary · Automation fundamentals, platforms and components
Transient response
Also known as: Step response, Dynamic response
German: Übergangsverhalten
In control engineering, the transient response is the time behavior of a system between an initial state and a new steady state after a change of input, such as a setpoint step or a disturbance. It is characterized by values like rise time, overshoot, settling time and damping.
- Automation components
In one sentence
Transient response is how a system moves to a new steady state after a change, described by rise time, overshoot and settling time.
Example
After a speed setpoint step, the drive overshoots by 8 % and settles within 120 ms, which is inside the specified limits.
How it applies
- Engineering: Controller tuning balances fast response against overshoot and stability. Overshoot can be unacceptable, for example in temperature control of sensitive products or in positioning near a mechanical end stop.
- Commissioning: Record step responses as evidence of loop tuning and compare them after later changes.
- Documentation: Specifications should give transient requirements as measurable values: maximum overshoot, settling time and tolerance band. "Fast and stable" is not testable. Keep the step response plots with the commissioning report.
Transient response vs. steady state
The transient response covers the journey; the Steady state is the destination. A loop can reach the right steady-state value and still be unacceptable because of large overshoot on the way.