In a second order under damped system, the

• time required for the response of first reach its ultimate value is called the response time.
• overshoot (which is a measure of how much the response exceeds the ultimate value) increase with the decrease of damping co-efficient e.
• decay ratio (which is the ratio of the sizes of successive peaks) is equal to the reciprocal of overshoot.
• characteristics of a step response is represented by