National Instruments 370753C-01

Chapter 4 System Analysis

From Figure 4-6 you see that the delay time (td) is about 0.5 seconds,

the rise time (tr) is 0.8 seconds, the peak time (tp) is 1.6 seconds, the

settling time (ts) is about 5.5 seconds, and the maximum overshoot (Mp)

is about 24%.

Figure 4-6. 15-Second Step Response, Showing Performance Measures

You can compute these values from the 151-point step response data vector

Y and substantiate your estimates.

First, you find the final value of the response:

Yf = makematrix(Y(151));

Get indices of all values > half the final value:

gt_half = find(Y > 0.5*Yf);

Time corresponding to first index in gt_half:

td = domain(Y(gt_half(1,1)))

td (a scalar) = 0.5

Get indices of all values > 0.1 * final value:

gt_1_10 = find(Y > 0.1*Yf);