how to use lsim command in matlab ?

hello

        i want to use lsim command to plot graph for system , i have read help but not getting proper idea

here is my code

***********************

clear all; clc; close all

load sec_sumsin_ABCDmatrix.mat % data As,Bs,Cs,Ds

syss=ss(As,Bs,Cs,Ds,0.001);

syssc=d2c(syss,'tustin');

[Asc,Bsc,Csc,Dsc]=ssdata(syssc);

nx=10; % states

ny=1; % output

nu=1; % input

M=diag([1.8108e0*ones(1,ny)]); %3.3058e-4];

QX=Csc'*M*Csc;

f=zeros(nx,1);

g=zeros(1,nx);

QU=diag([3.9805e-8*ones(1,nu)]);

QXU=[QX f;g QU];

n=randn(11,11)

KlQG=lqg(syssc,QXU,n)

[aa,bb,cc,dd]=ssdata(KlQG)

KlQG.InputName = 'q'; KlQG.OutputNmae = 'u';

syssc.InputName = 'u'; syssc.Outputname = 'y';

sum = sumblk('q = n + y');

sysc = connect(syssc,sum,KlQG,'n','y')

******************************************

in the figure shown (n) is noise added at output side of plant and measure output is (q) and i want to use lsim command to plot results from noise to measure output , how should i do this ?

Answer 1

[Arkadiy Turevskiy]

Is the code you provided giving you an error? Once you build your transfer function from n to y, you should be able to simulate it with lsim:

    t = 0:0.01:5;   
    u = sin(t);   
    lsim(sysc,u,t);

[Aniket]

In the above code its not giving me error but i think its not proper but how should i build transfer function from n to y ?

I have done some modification in code just check

upto QXU the code is same as above

*************************

QW=1e-3*eye(nx);

QV=randn(ny,ny);

QWV=[QW f;g QV];

KlQG=lqg(syssc,QXU,QWV) % desing LQG regulator

[aa,bb,cc,dd]=ssdata(KlQG)

sum = sumblk('yo=y+QV')

syssc.u ='u'; syssc.y='y';

KlQG.u='yo'; KlQG.y ='u';

T = connect (syssc,KlQG,sum,'u','yo')

*****************************************

in this its give me warning

Warning: The following block inputs are not used: QV.

[Arkadiy Turevskiy]

Sorry, I did not read your initial question carefully: you want response to the measured output, with noise included. In that case you simply do:

   sysc = connect(syssc,sum,KlQG,'n','q');
   % transfer function from noise to measured output
   t = 0:0.01:5;   
   n = sin(t);   %replace with desired input
   lsim(sysc,n,t);

[Aniket]

Thank You

Could I send you email if i have a doubts because this area is new for me