Vasteaika

Vasteaika is a term used in Estonian technical language to describe the time interval from when a stimulus is applied to a system until the system’s output reaches a predefined level or remains within a specified tolerance around its final value. The exact criterion used to declare that the response has been completed can vary by discipline, for example a fixed percentage band around the final value or a specific threshold crossing.

Etymology and scope: The word combines vast(e) meaning response and aeg meaning time in Estonian. In practice, vastaaika is a fundamental measure of how quickly a device, mechanism, or interface reacts to input, and it is discussed across fields such as control theory, electronics, computing, and human–computer interaction.

Applications: The concept is used to assess performance and usability. In control engineering, the vastaaika is closely related to, but distinct from, related measures such as rise time and settling time; it depends on system order, feedback, and damping. In computing and user interfaces, it reflects perceived responsiveness and can influence user satisfaction and task efficiency. In electronics and physical systems, it describes how rapidly a sensor, actuator, or circuit responds to a stimulus.

Measurement and interpretation: Vastaaika is typically determined from a known input (often a step input) and involves identifying when the output meets the chosen criterion. Real-world systems may exhibit overshoot, oscillation, or nonlinearities that affect the measured value.

Relation to latency: While related to latency, vastaaika refers to the internal reaction time of the system rather than network or transmission delays.

See also: Response time, Settling time, Rise time, Latency.