User`s guide
Identifying Low-Order Transfer Functions (Process M odels)
Usethefollowingcommandstoestimateamodelm from sample data:
% Load sample data
load co2data
% Sampling interval is 0.5 min (known)
Ts = 0.5;
% Split data set into estimation data ze
% and validation data zv
ze = iddata(Output_exp1,Input_exp1,Ts,...
'TimeUnit','min');
zv = iddata(Output_exp2,Input_exp2,Ts,...
'TimeUnit','min');
% Estimate model with one pole and a del ay
m = pem(ze,'P1D')
MATLAB co mputes the following outpu t:
Process model with 2 inputs:
y = G_1(s)u_1 + G_2(s)u_2
where
K
G_1(s) = ---------- * exp(-Td*s)
1+Tp1*s
with K = -3.2168
Tp1 = 23.033
Td = 10.101
K
G_2(s) = ---------- * exp(-Td*s)
1+Tp1*s
with K = 9.9877
Tp1 = 2.0314
Td = 4.8368
Use dot notation to get the v alue of any model parameter. For example, to get
the
Value field in the K s tructure, type the followi ng command:
m.K.value
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