function [B,A]=vi_maux(y,u,na,nb,d,Fin,lam1,lam0) % VIMAUX is used to identify a discrete time model of a plant operating in % open-loop based on the method of instrumental variable with auxiliary % model % % [B,A]=vi_maux(y,u,na,nb,d,Fin,lam1,lam0) % % y and u are the column vectors containing respectively the output and the % excitation signal. % % na, nb are the order of the polynomials A,B and d is the pure time delay % % % Fin is the initial gain F0=Fin*(na+nb)*eye(na+nb) (Fin=1000 by default) % % lam1 and lam0 make different adaptation algoritms as follows: % % lam1=1;lam0=1 :decreasing gain (default algorithm) % 0.952, error('This routine is only for SISO systems'),end [nl,nc]=size(u); if nc>2, error('This routine is only for SISO systems'),end if (na<0 | nb<0 | d<0), error('The order of A,B and d should not be negative!!'),end nd=min(length(u),length(y)); % number of data nth=na+nb; if nd1 | lam0>1), error('lam1 and lam0 should be less than 1');end if (lam1<0.95 | lam0<0.95), disp ('warning :lam1 and lam0 are normally greater than 0.95');end theta=zeros(nth,1); phi=zeros(2*np,1); phi_vi=zeros(2*np,1);%phi for instrumental variable F=Fin*nth*eye(nth); i=[1:np-1 np+1:2*np-1]; %shift index for vector phi j=[1:na np+d+1:np+d+nb]; %phi index for theta for t=1:nd yhat=theta'*phi(j); yhat_vi=theta'*phi_vi(j); e_apri=y(t)-yhat; e_apost=e_apri/(1+phi_vi(j)'*F*phi_vi(j)); theta=theta+F*phi_vi(j)*e_apost; F=1/lam1*(F-((F*phi_vi(j)*phi_vi(j)'*F)/(lam1+phi_vi(j)'*F*phi_vi(j)))); lam1=lam0*lam1+1-lam0; phi(i+1)=phi(i);phi(1)=-y(t);phi(np+1)=u(t); if t>2*np*6, phi_vi(i+1)=phi_vi(i);phi_vi(1)=-yhat_vi;phi_vi(np+1)=u(t); else phi_vi(i+1)=phi_vi(i);phi_vi(1)=-y(t);phi_vi(np+1)=u(t); end; end A=[1;theta(1:na)]'; B=[zeros(d+1,1);theta(na+1:na+nb)]';