nwidARMAX_dcn function

Identify a full diffusively coupled network or a subnetwork from a diffusively coupled network using the ARMAX-like method.

Syntax

• model = nwidARMAX_dcn(data,model,orders,options)  performs identification based on the provided data, initialized network model, model orders and option set. The identified network/subnetwork model is returned.

Input arguments

• data

  nwdata object

  Network data object. The input excitation, input node and output node signals (as referred to by their labels) in the Rset, Dset and Yset of the predictor model must be present in the data.

• model

  nwpredmodel object	nwmodel object

  Initialized network model object. Use an nwmodel object to identify the full network, and an nwpredmodel object to identify a subnetwork. The properties of the predictor mappings X, Y, B and F are used in the algorithm, with some restrictions:

  • At least 1 excitation is required to run estimation (i.e. B has at least 1 non-zero entry)
  • The algorithm currently only supports Variable = z^-1, hence only discrete-time identification is possible.
  • Since X, Y and B are polynomials, the number of denominator parameters npden must equal 0 for each element in these mappings.
  • For each element of X, it is assumed that the order (npnum) is at least 1 higher than the maximum order (npnum) of the corresponding row/column of Y.
  • Delay settings (d) are ignored.
  • Setting initial parameter values using pnum/pden is not supported.

• orders

  structure array

  Model orders. Can be used to override properties of the initialized network model object. Use a structure array with optional fields:

  • nA: Order of X elements, and order+1 of Y elements (nA = model.X.npnum-1 = model.Y.npnum)
  • nB: Order of B elements (nB = model.B.npnum-1)
  • nF: Order of F elements (nF = model.F.npnum-1)
  • nAim: Order of X elements, and order+1 of Y elements modified by immersion.

  All elements outside of the target subnetwork will be estimated with order nAim to account for the immersed dynamics, and the target subnetwork will be directly estimated with order nA.

• options

  nwidARMAXOptions object

  Option set for nwidARMAX_dcn function. Can be constructed using options = nwidARMAXOptions for the default option set or options = nwidARMAXOptions(Name=Value,...) to set specified options.

Output arguments

• model

  nwpredmodel object	nwmodel object

  Estimated network model object. This is an nwmodel object after full network identification, and an nwpredmodel object after subnetwork identification. The pnum and pden properties of the X, Y, B and F fields are populated with the estimated parameter values. The e properties of X, Y, B and F contain the fixed and estimated polynomials/transfer functions of the predictor model connections.