User`s guide

Identifying Hammerstein-Wiener Models
Example – Using nlhw to Estimate Hammerstein-Wiener
Models
This example uses nlhw to estimate a Hammerstein-Wiener model for
the two-tank system. The data for this system is described in “Tutorial –
Identifying Nonlinear Black-Box Models Using the G U I ” in the System
Identification Toolbox Getting Started G uide.
Prepare th e d ata for estimation u sin g the following commands:
load twotankda ta
z = iddata(y, u, 0.2);
ze = z(1:1000); zv = z(10 01:3 000);
Estimate several m odels using diff erent model orders, delays, and
nonlinearity settings:
m1 = nlhw(ze,[2 3 1],'pwl','pwl');
m2 = nlhw(ze,[2 2 3],'pwl','pwl');
m3 = nlhw(ze,[2 2 3], pwl inea r('num',13),...
pwlinear('num',10));
m4 = nlhw(ze,[2 2 3], sig moid net('num',2),...
pwlinear('num',10));
m5 = nlhw(ze,[2 2 3], 'de ad', 'sat');
Compare the resulting models by plotting the model outputs on top of the
measured output:
compare(zv,m1,m2,m3,m4,m5)
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