System identification
seminar class Active In SP Posts: 5,361 Joined: Feb 2011 
14022011, 03:26 PM
presented by: HOSSEIN NEJATBAKHSH system identification.pptx (Size: 511.63 KB / Downloads: 62) What is identification? System identification is the art and science of building mathematical models of dynamic systems from observed inputoutput data. it’s an interface between the real world of applications and the mathematical world of control theory. in control engineering the field of system identification uses statistical methods to build mathematical models of dynamical systems from measured data. The core of estimating models is statistical theory. Other Definition Zadeh(1962) Identification is the determination on the basis of input and output, of a system within a class of systems, to which the system under test is equivalent. •Parameter estimation is the experimental determination of values of parameters that govern the dynamic and/or nonlinear behaviour, assuming that the structure of the model is known. System identification and parameter estimation Model validation Identification: timedomain & frequencydomain Time domain • y(t) = ∫ h(t’)u(tt’)*dt’ + n(t) • Unknown system: impulse response of h(t’) • Mostly: direct model parameterization Frequency domain • Y(ω) = H(ω)U(ω) + N(ω) • Unknown system: transfer function H(ω) for number of frequencies • Open loop identification Car shock absorber testing • Response loudspeaker • Knee jerk reflex • Etc, etc Ti[b]medomain & Frequencydomain Crossproduct function Autoproduct function Covariance and correlation functions Special cases of autocovariance Open loop identification(time domain)with crosscovariance Open loop identification(frequency dom[/b]ain) Identification in the closed loop • Time domain models for identification Least squares (LS) • ARX • ARMAX • Output Error (OE) • FIR Least squares model • equation system • Least Squares (LS) Method (LUENBERGER, D. G. 1996) • minimization =⇒the best linear nondeviated estimation Identification of Dynamical Systems ARX model (Auto Regresive model with eXternal input)– prediction of mean value ˆy(tt − 1) is linear function of measurable datalinear regression can be used for model parameters stimation • ARMAX model (Average model with eXternal input)enables us to model deterministic and stochastic parts of the system independentlylinear regression cannot be used for model parameters estimation→pseudolinear reg. OE model (Output Error model) Example  Model Identification Using ARX Model FIR MODEL Finite impulse response(FIR) models are frequently used in model Predictive control (MPC) systems because they can fit arbitrarily Complex stable linear dynamics. However , identification of FIR models from experimental data my result in dataover fitting and high modeling uncertainly. To overcome this, FIR models may be determined by : (a) regularization – based least squares, and (b) indirectly after prior identification of other parametric models such as ARX. 



Important Note..!
If you are not satisfied with above reply ,..PleaseASK HERE
So that we will collect data for you and will made reply to the request....OR try below "QUICK REPLY" box to add a reply to this pagePossibly Related Threads...  
Thread  Author  Replies  Views  Last Post  
power theft identification ppt  jaseelati  0  203 
06022015, 04:45 PM Last Post: jaseelati 

microcontroller based power theft identification ppt  jaseelati  0  194 
06022015, 03:29 PM Last Post: jaseelati 

user identification and authentication systems must support the minimum requirements  jaseelati  0  273 
29112014, 04:19 PM Last Post: jaseelati 

ZIGBEE WIRELESS VEHICLE IDENTIFICATION AND AUTHENTICATION SYSTEM ppt  seminar tips  0  732 
08012013, 02:32 PM Last Post: seminar tips 

Enhance Identification And Removal of Threats By Misbehaving Nodes And Optimizing  seminar class  0  135 
12042011, 11:13 AM Last Post: seminar class 

System design & developement in calculation of response time for air brake system  Computer Science Clay  1  2,367 
11032011, 04:02 PM Last Post: seminar class 