Numeric Values of Time-Domain System Characteristics
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
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.