# Percentage overshoot (PO)

## Description

In signal processing, control theory, electronics, and mathematics, overshoot is the occurrence of a signal or function exceeding its target. It arises especially in the step response of bandlimited systems such as low-pass filters. It is often followed by ringing, and at times conflated with the latter.

Maximum overshoot is defined in Katsuhiko Ogata’s Discrete-time control systems as “the maximum peak value of the response curve measured from the desired response of the system”.

In control theory, overshoot refers to an output exceeding its final, steady-state value. For a step input, the percentage overshoot (PO) is the maximum value minus the step value divided by the step value. In the case of the unit step, the overshoot is just the maximum value of the step response minus one.

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