NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/sci/engr/control/284

Text File | 1992-11-17 | 1.8 KB | 40 lines

Newsgroups: sci.engr.control
Path: sparky!uunet!charon.amdahl.com!pacbell.com!sgiblab!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!csn!news.den.mmc.com!stote
From: [e-mail] (M. Stote)
Subject: Re: Simulink problem!
Message-ID: <[e-mail]>
Sender: stote@tomcat (M. Stote)
Nntp-Posting-Host: tomcat.den.mmc.com
Organization: Martin Marietta Astronautics Group
References:  <[e-mail]>
Date: Tue, 17 Nov 1992 18:30:57 GMT
Lines: 27

In article <[e-mail]>, [e-mail] (Guoqiano Lu) writes:
|>
|> I am using Simulink to simulate continuous-time self-tuning algorithms. Generally it works well except
|> sometimes there are some crazy peaks in the output which is supposed to be smooth. It seems to me
|> that these are due to the numerical intrgration algorithms that SimuLink used. Any one has the same
|> experiences or any suggestions to overcome this problem?

I had some similar problems when simulating a system which had both
very fast and very slow dynamics, as well as high levels of noise
and disturbance inputs.  I had to `tune' the integration parameters
of max & min integration step size and integration error tolerance.
I did this heuristically, varying them until I `optimized' simulation
speed and `smoothness'.
   I unfortunately know little about this area and would appreciate
any formalism someone could bring to this topic.

  The fact that you are using a self-tuning algorithm has me a little
suspicious.  Are you sure your peaks in the output are not a result
of the self-tuning algorithm `losing track'  ?
  Do you see similar peaks in the output if you use a non-adaptive
controller ?  Of course you may not, and it may still be the integration
algorithm having trouble handling the time variation of the tuning
algorithm.

--
Mike Stoughton
[e-mail]