Control System Toolbox™

lsiminfo - Compute linear response characteristics

Syntax

S = lsiminfo(y,t,yfinal)
S = lsiminfo(y,t)
S = lsiminfo(...,'SettlingTimeThreshold',ST)

Description

S = lsiminfo(y,t,yfinal) takes the response data (t,y) and a steady-state value yfinal and returns a structure S containing the following performance indicators:

• SettlingTime — Settling time

• Min — Minimum value of Y

• MinTime — Time at which the min value is reached

• Max — Maximum value of Y

• MaxTime — Time at which the max value is reached

For SISO responses, t and y are vectors with the same length NS. For responses with NY outputs, you can specify y as an NS-by-NY array and yfinal as a NY-by-1 array. lsiminfo then returns an NY-by-1 structure array S of performance metrics for each output channel.

S = lsiminfo(y,t) uses the last sample value of y as steady-state value yfinal. s = lsiminfo(y) assumes t = 1:NS.

S = lsiminfo(...,'SettlingTimeThreshold',ST) lets you specify the threshold ST used in the settling time calculation. The responsehas settled when the error |y(t) - yfinal| becomes smaller than a fraction ST of its peak value. The default value is ST=0.02 (2%).

Example

Create a fourth order transfer function and ascertain the response characteristics.

sys = tf([1 -1],[1 2 3 4]);
[y,t] = impulse(sys);
s = lsiminfo(y,t,0)  % final value is 0
s = 

    SettlingTime: 22.8626
             Min: -0.4270
         MinTime: 2.0309
             Max: 0.2845
         MaxTime: 4.0619

See Also

lsim, impulse, initial, stepinfo, ltimodels

lsim

lsimplot