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Numeric Values of Time-Domain System Characteristics

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This example shows how to obtain numeric values of step response characteristics such as rise time, settling time, and overshoot using stepinfo. You can use similar techniques with lsiminfo to obtain characteristics of the system response to an arbitrary input or initial conditions.

Create a dynamic system model and get numeric values of the system’s step response characteristics. 

H = tf([8 18 32],[1 6 14 24]);
data = stepinfo(H)
data = struct with fields:
         RiseTime: 0.2087
    TransientTime: 3.4972
     SettlingTime: 3.4972
      SettlingMin: 1.1956
      SettlingMax: 1.6871
        Overshoot: 26.5302
       Undershoot: 0
             Peak: 1.6871
         PeakTime: 0.5987

The output is a structure that contains values for several step response characteristics. To access these values or refer to them in other calculations, use dot notation. For example, data.Overshoot is the overshoot value.

Calculate the time it takes the step response of H to settle within 0.5% of its final value. 

data = stepinfo(H,'SettlingTimeThreshold',0.005);
t05 = data.SettlingTime
t05 = 4.8896

By default, stepinfo defines the settling time as the time it takes for the output to settle within 0.02 (2%) of its final value. Specifying a more stringent 'SettlingTimeThreshold' of 0.005 results in a longer settling time.

For more information about the options and the characteristics, see the stepinfo reference page.

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