Sysquake Pro – Table of Contents

Sysquake – Table of Contents

Sysquake for LaTeX – Table of Contents

id_p.sq

Parametric identification

First contact

SQ file id_p.sq provides the identification methods to obtain an ARX parametric model based on the measured input and output of an unknown system. The data can be retrieved from a file (typically created by an external real-time acquisition program) or generated by the SQ file.

For didactic purposes, synthetic data can be created for input u(t) and output y(t). Data are obtained by simulating system G(s)=1/(s^2+2s+3) sampled at Ts=0.1 with a square input and noise filtered by the model denominator (ARX model). For applications to real systems, experimental data can be read from files.

The parameters of the following model are identified:

where A=1+a1.q^-1+...+an.q^-n and B=b1+b2.q^-1+...+bm.q^-m. The order of polynomials m and n, and the delay d, must be specified.

Settings

Create Synthetic Data

Synthetic data are created from scratch. A dialog box allows to choose the number of samples.

Read Data File

The measurements are read from a text file, typically created by an acquisition program. This file should contain an array of two column (separated by spaces or tabulators) by n row (separated by carriage returns and/or line feeds). The first column corresponds to the system input, and the second column to the system output. Each row corresponds to a sample.

Model Degree

Samples Used For Identification

Not all samples are used for identifications. Remaining samples are useful for validating the model (cross-validation). The number of samples used for identification can also be set by manipulating the red vertical line in figure "Output".