[Scilab-users] System Identification for First order delay and dead time

[tim at wescottdesign.com]

I suggest that you roll your own cost function, and use optim.

Where possible, with optim, if part of the problem is nonlinear and part 
is linear, it's good to use a plain old linear least-squares fit for the 
plain old linear part.  In your case, that's K.  Tau and Td will have to 
be determined by optim.

The cost function should generate a vector for ymodel with K = 1, then 
find the best fit for K with

K = y / ymodel;

then return a cost

cost = norm(y - K * ymodel);

wrap that all up in NDCost and then optim, and away you'll go.

On 2016-09-24 06:59, Fukashiimo wrote:
> Hello,
> 
> I am looking for a Scilab software which is similar to Matlab System ID 
> tool
> box.
> 
> I would like to obtain values of parameters, Tau, K and Td for 
> following
> first order delay + Dead time model from time series data.
> ymodel = (K/(Tau*s+1))*exp(-Td*s)*u
> ymodel: process output, u: process input
> SISO continuous time
> 
> Object function: Min ( (y-ymodel)^2)
> 
> Could you please tell me which package I should use to solve this 
> issue?
> 
> Best Regards,
> 
> 
> 
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