1 The System Identification Problem data sets using subsets of the original input/output channels. Use the pop-up menu Preprocess>Select Channels for this. Dont change the validation Data. The GUI will keep track of the input and output channels. It will"do the right thing"when evaluating the channel-restricted models using the Validation Data. It might also be appropriate to see if improvements in the fit are obtained for various model types, built for one output at a time If you decide for a multi-output model, it is often easiest to use state-space models. Use nasi d as a primary tool and try out pem when a good order has been found 120
1 The System Identification Problem 1-20 data sets using subsets of the original input/output channels. Use the pop-up menu Preprocess > Select Channels for this. Don’t change the Validation Data. The GUI will keep track of the input and output channels. It will “do the right thing” when evaluating the channel-restricted models using the Validation Data. It might also be appropriate to see if improvements in the fit are obtained for various model types, built for one output at a time. • If you decide for a multi-output model, it is often easiest to use state-space models. Use n4sid as a primary tool and try out pem when a good order has been found
Reading More About System Identification Reading more about system Identification There is substantial literature on System Identification. The following textbook deals with identification methods from a similar perspective as this toolbox, and also describes methods for physical modeling Ljung L and T Glad Modeling of Dynamic Systems, Prentice Hall, Englewood Cliffs, N.J. 1994 For more details about the algorithms and theories of identification Ljung L System Identification- Theory for the User, Prentice Hall, Upper Saddle river.N.. 2nd edition, 1999 Soderstrom T and P Stoica. System Identification, Prentice Hall International. London 1989 For more about system and signals Oppenheim J. and A.S. Willsky Signals and Systems, Prentice Hall, Englewood Cliffs, N.J. 1985 The following textbook deals with the underlying numerical techniques for Dennis. J.E. r and r.B. schnabel. Numerical methods for Unconstrained Optimization and Nonlinear equations, Prentice Hall, Englewood Cliffs, N.J.1983 1-21
Reading More About System Identification 1-21 Reading More About System Identification There is substantial literature on System Identification. The following textbook deals with identification methods from a similar perspective as this toolbox, and also describes methods for physical modeling: • Ljung L. and T. Glad. Modeling of Dynamic Systems, Prentice Hall, Englewood Cliffs, N.J. 1994. For more details about the algorithms and theories of identification: • Ljung L. System Identification - Theory for the User, Prentice Hall, Upper Saddle River, N.J. 2nd edition, 1999. • Söderström T. and P. Stoica. System Identification, Prentice Hall International, London. 1989. For more about system and signals: • Oppenheim J. and A.S. Willsky. Signals and Systems, Prentice Hall, Englewood Cliffs, N.J. 1985. The following textbook deals with the underlying numerical techniques for parameter estimation: • Dennis, J.E. Jr. and R.B. Schnabel. Numerical Methods for Unconstrained Optimization and Nonlinear Equations, Prentice Hall, Englewood Cliffs, N.J. 1983
1 The System Identification Problem 1-22
1 The System Identification Problem 1-22
The Graphical User Interface The Big Picture 2-2 Handling Data 2-7 Estimating Models 2-15 Examining models 2-28 Some Further GUI Topics 2-35
2 The Graphical User Interface The Big Picture . . . . . . . . . . . . . . . . . . 2-2 Handling Data . . . . . . . . . . . . . . . . . . . 2-7 Estimating Models . . . . . . . . . . . . . . . . . 2-15 Examining Models . . . . . . . . . . . . . . . . . 2-28 Some Further GUI Topics . . . . . . . . . . . . . . 2-35
2 The Graphical User Interface The Big picture The System Identification Toolbox provides a graphical user interface(GUI) The GUI covers most of the toolbox's functions and gives easy access to all variables that are created during a session. It is started by typing i dent in the matlab command window File Options Window Help Mode曰 Operations Data views Model views ■ Time plot 口 Model output口 Transient resp 口 Data spectra Model resid Frequency resp] 口 Zeros and poles 口 Noise spectrum Figure 2-1: The Main ident Information Window The Model and data boards System Identification is about data and models and creating models from data The main information and communication window ident, is therefore dominated by two tables a table over available data sets, each represented by an icon A table over created models, each represented by an icon 2-2
2 The Graphical User Interface 2-2 The Big Picture The System Identification Toolbox provides a graphical user interface (GUI) . The GUI covers most of the toolbox’s functions and gives easy access to all variables that are created during a session. It is started by typing ident in the MATLAB command window. Figure 2-1: The Main ident Information Window The Model and Data Boards System Identification is about data and models and creating models from data. The main information and communication window ident, is therefore dominated by two tables: • A table over available data sets, each represented by an icon • A table over created models, each represented by an icon