Identification of Non-Linear Dynamic Systems using an Expert Approach

An Expert System approach for the identification of non-linear systems is presented.
The Expert System is an attempt to bring order into the non-linear system identification
process. The final objective is to deliver a parsimonious mathematical model of the dy-
namical system under investigation. It works by defining the key stages of the procedure
and iterating between them if necessary. It takes advantage of numerous methodologies to
accomplish the tasks in each of the stages and uses the results from many of them. The
Expert System applies the excitation forces appropriate to each method and analyses the
responses. Each stage ends with a set of recommendations that can be used to begin the
next stage.
The Expert System is applied to a simple non-linear dynamic system. It is shown
that the Expert System procedure can automatically detect, locate and quantify the non-
linearity using its array of techniques. Furthermore, it can choose a suitable model struc-
ture, select appropriate terms and estimate the model parameters using an extensive set
of rules. The resulting identified model is validated and shown to be an accurate represen-
tation of the experimental system.