FID Fractional-order Transfer Function SISO system identification
Usage: [A,NA,B,NB,L,GID] = FID(FSIM|G,IDD,FIXPOLY,CLIM,ELIM,TYPE,NPOINTS,OP)
where A,NA,B,NB, L and GID - identified system coefficients, input/output
delay from delay term exp(-Ls) and FOTF object
FSIM | G - either FSPARAM structure to use approximations for
identification with the initial function or the
initial function as a FOTF object. If the FOTF object
has a set ioDelay value, it will also be identified
in the ensuing optimization. To ignore the delay
parameter set it to [] (i.e. empty matrix) in the initial
model.
IDD - a FIDATA sturcture with collected system samples
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Optional arguments
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FIXPOLY - a vector with two values: [BFIX; AFIX], where BFIX
and AFIX can be 1, in which case the corresponding
polynomial is fixed during identification, or 0.
Note that in case BFIX = AFIX = 1 the initial model
will be immediately returned with no identification
conducted. Default: [0; 0]
CLIM - coefficient limits in form [CMIN; CMAX]. Supply an
empty matrix [] to suppress limits (default: [])
ELIM - exponent limits in form [EMIN; EMAX]. [] will
suppress limits (default: [])
TYPE - identification type: 'n' - free identification,
'c' - fix coefficients, 'e' - fix exponents
(default: 'n')
NPOINTS - number of points to use for identification; this
allows to reduce the time it takes to estimate a
model, i.e. for obtaining an initial estimate, at an
expense of accuracy. If the number of points
specified here is larger than half the number of
points in the dataset, all available points will be
used for identification. Specifying 0 or [] will
yield the same effect and it is also the default
behavior.
OP - additional optimization options for lsqnonlin
(use optimset)
See also: fsparam, fidata, optimset, lsqnonlin