I need help using embedded matlab functions for an iterative learning controller

Question

Rune 2013-3-19

0
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https://ww2.mathworks.cn/matlabcentral/answers/67811-i-need-help-using-embedded-matlab-functions-for-an-iterative-learning-controller

I am working with a learning controller for a motor for a periodic signal. I want to store the followerror on each time sample during the first period, in a vector. Then I want to output these values the next period, and also rewrite them with the new followerror.

currently I am using:

function y = fcn(u,t)
%#codegen
d=round(t); 
z=zeros(1,99999); 
y=z(1,d+1);
z(1,d+1)=u;

t is a time counter that resets every period

but this doesn't seem to work, it keeps showing zero... Can anyone help me?

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Answer 1

Kaustubha Govind 2013-3-19

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在 MATLAB Online 中打开

You are using the variable 'z' as a state, but note that the line:

z=zeros(1,99999);

is executed at every time-step, so 'z' is reset to all zeros every time. You might want to define 'z' as a persistent variable instead:

function y = fcn(u,t)
%#codegen
persistent z;
d=round(t); 
if isempty(z)
  z=zeros(1,99999); 
end
y=z(1,d+1);
z(1,d+1)=u;

PS: You might also want to look into whether you are assigning 'z' correctly, you are using y=z(1,d+1), but z(1,d+1)=u; only on the next line. Did you mean to say y=z(1,d)?