2011/8/17 Jordi Gutiérrez Hermoso <jord...@octave.org>: > > That being said, what is the system identification toolbox? The > Mathworks makes it look like it's a combination of Simulink with > something else. >
There may be connections with Simulink, but on the whole it doesn't have anything to do with it. The toolbox is based upon the book, "System Identification - Theory for the User" By Lennart Ljung. It uses various methods to get models of a system. Basically, it fits data to differing kinds of models. The method I use ETFE (Empirical Transfer Function Estimate) in the end gives a frequency spectrum corresponding to the system's plant (based upon the given input and output data). It's different than just doing a FFT on the output data. But there are methods for Linear Time-Invariant systems, as well as time-varying and non-linear systems. Most of the toolbox is centred around these models and parameter estimation. Using the ETFE I'm not limited to a specific model since the approach treats the system like a black box getting a model of what happens based upon input and output data alone rather than trying to fit to a specific modelling approach (other than assuming the system is linear). Documentation: http://www.mathworks.com/help/toolbox/ident/ And the specific function I use most: http://www.mathworks.com/help/toolbox/ident/ref/etfe.html One of the advantages is that I can customize the output frequency resolution. This is handy when I'm trying to find the natural frequency since I need good resolution around the damped natural frequency peaks. Cheers, Tim. -- Tim Lahey PhD Candidate, Systems Design Engineering University of Waterloo http://about.me/tjlahey -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
