[Scilab-users] Optimization: First order delay and dead time TF model ID, CUTEr

[noguchi]

Tim,

Thank you for your message.

I read datafit help several times. However, it is quite difficult for me to understand it.

> Model: ym(n)=ym(n-1)*amp+Kpm*bmp*u(n-1-Tdm)  where n=step=1:1:500)
> Where amp=exp(-Tsample/Taup), Tsample=1, bmp=1-amp
> Object function: sum of square of (y(n)-ym(n)) 

Variables to be changed to minimize the value of object functions are: Kp, Taup and Tdm

How should I write Scilab commands for this problem?


Thanks,


Y. Noguchi


----- 元のメッセージ -----
差出人: "Tim Wescott [via Scilab / Xcos - Mailing Lists Archives]" <ml-node+s994242n4033860h28 at n3.nabble.com>
宛先: "noguchi" <noguchi at kje.biglobe.ne.jp>
送信済み: 2016年3月26日(土曜日) 02:57:03
件名: Re: Optimization: First order delay and dead time TF model ID, CUTEr

On Fri, 2016-03-25 at 09:54 -0700, noguchi wrote: 

> Hello, SCilab Users, 
> 
> May I ask your help? 
> 
> I still not find practical solution to minimize my object function by Scilab 
> tools. 
> Model: ym(n)=ym(n-1)*amp+Kpm*bmp*u(n-1-Tdm)  where n=step=1:1:500) 
> Object function: sum of square of (y(n)-ym(n)) 
> 
> 
> Using Excel, I made same objective funtion and minimize it by solver. The 
> solution is sometimes good but some times bad. Therefore, I still need 
> Scilab code to solve this problem. 
> 
> May I ask how I can wrote scilab commend to solve this problem? 
> 
> Thank you for your help. 
> 
> 
> Y. Noguchi FODDT_ModelID_SISO_r0.xls 
> < http://mailinglists.scilab.org/file/n4033859/FODDT_ModelID_SISO_r0.xls >   
> 
> 
> 
> 
> 
> 
> -- 
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> 
I don't have time to work up an example of this, but -- have you looked 
at the help page for datafit?  It looks like it'll do the job (I know 
how to do this with optim, but I suspect that I should have been using 
datafit for a lot of that stuff). 

You may want to make sure you know what you're optimizing _for_ -- I 
assume that ym(0) = 0, and that amp, Kpm, bmp and Tdm are your free 
parameters. 

If so, you may want to revisit your problem -- Kpm and bmp are 
redundant; if you're trying to optimize on both of them then you may be 
confusing the optimizer. 

-- 

Tim Wescott 
www.wescottdesign.com 
Control & Communications systems, circuit & software design. 
Phone: 503.631.7815 
Cell:  503.349.8432 





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