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How can I measure length of signal in simulink?

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George Francis
George Francis 2018-3-17
评论： Jim Riggs 2018-3-19
Hello guys, I have model with "matlab function block" in which I have recursive least square method. Recursive algorithm needs to know length of incoming signal in order to work correctly. But when I use command N=length(y) it returns me length N= 1. But I think it should give me higher length.
Matlab function block code "rls_iden6"
function [P,N] = fcn(u,y)
N = length(y);
sigma=1;
C = sigma*eye(2); %p
P = ones(2,1);
z= [y; u];
lamda=1;
for n=1:N
sample_out = y(n);
C = (C - ( (C*z*z'*C)/( lamda+(z'*C*z) ) ))/lamda;
P = P + (C*z* (sample_out - (z'*P)));
end
My final code should look like it's shown below, because it works in matlab workspace. Simulink should give me 5 parameters instead of just 2.
load data_cela.mat
u=U; %input
y=Y; %output
input = 3;
output = 2;
system = input + output;
N = length(y);
%initial conditions
sigma = 1;
C = sigma*eye(system);
P = ones(system,1);
lamda = 1; %forgetting factor
for n=3:N
for i=1:2
W(i) = y(n-i); %output
end
for i=1:3
V(i) = u(n-i+1); %input
end
z = [V';W'];
sample_out = y(n);
pom(n)= z' * P;
error(n) = y(n) - pom(n);
C = (C - ( (C*z*z'*C)/( lamda+(z'*C*z) ) ))/lamda;
P = P + (C*z* (sample_out - (z'*P) ) );
change(1:system,n) = P;
end
f_param = [P(1:3);-P(4:5)];
num = [P(1:3,1)];
den = [1;-P(4:5,1)];
num1 = num(3,1);
trasferfunction = tf(num1,den',1)
Result:
0.002879
----------------------
z^2 - 1.883 z + 0.8873
  1 个评论
Jim Riggs
Jim Riggs 2018-3-19
Verify the signal size in Simulink. In the Simulink window, select Display / Signals & Ports / Signal Dimensions.
This will show the signal size (according to Simulink) in your model.

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