[Scilab-users] PID tuning with Optimization

[Gona]

Hi All,

I was trying to tune my PID controller following this article.
http://wiki.scilab.org/Xcos/Examples/PID

I have setup my environment like this,

<http://mailinglists.scilab.org/file/n4030508/BikeModelWith_PID.gif> 
<http://mailinglists.scilab.org/file/n4030508/BikeContextParameters.gif> 

And up to the first simulation, the process went well.

<http://mailinglists.scilab.org/file/n4030508/Bike-SimulationOK.gif> 

I got a warning for the CMSCOPE but I guess it has nothing to do with this
problem.
*CMSCOPE('set'): Wrong size for block parameter 'Refresh period': 2
expected, getting 30 30 30 30 *

But when I tried to start the optimization, I got this error.

*-->[f_opt, x_opt] =
optim(my_optim_pid,'b',Lower,Upper,x0,algo='qn','ar',MaxEvalFunc,MaxEvalFunc,1e-3,1e-3,[1e-3;1e-3]);
 
 CMSCOPE('set'): Wrong size for block parameter 'Refresh period': 2 expecte 
      d, getting 30 30 30 30                                                
 !--error 21 
Invalid index.
at line      12 of function f_pid called by :  
at line       2 of function my_optim_pid called by :  
unc,MaxEvalFunc,1e-3,1e-3,[1e-3;1e-3])*

My f_pid function goes like this.

*function y = f_pid(x)
  global Iter;
  %scicos_context.l = l
  %scicos_context.g = g
  %scicos_context.v = v
  %scicos_context.phi = phi
  %scicos_context.w = w
  %scicos_context.P  = x(1)*Pfact;
  %scicos_context.I  = x(2)*Ifact;
  Iter = Iter + 1;
  Info = scicos_simulate(scs_m,list(),%scicos_context,flag='nw');
  y_error = mean(abs((block_output('values')(:,1) - 
block_output('values')(:,2))));
  y_diff  = mean(abs(diff(block_output('values')(:,2))));
  y = 0.5*y_error + 0.5*1*y_diff; ...
  printf('Evaluation %d - P = %f I = %f y = %f (y_error = %f, y_diff =
%f)\n',Iter,x(1),x(2),y,y_error,y_diff);
endfunction*

I guess the problem lies in the block_output variable.
When I tried to see the content of the block_output('values')(:,2) I got the
same error.

*-->block_output('values')(:,2)
                            !--error 21 
Invalid index.*

I guess in my system the block_output is not in the same dimensions as that
of the example shown in the article. How can I fix this issue.

Anyone please shed some light on this issue ? 
and how can I add the D gain in to the optimization ?

any help is highly appreciated.

Thanks
BR
Gona









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