Re: Problem in OCST

[Doug Stewart]

ผศ.ดร.ศุภชัย วรพจน์พิศุทธิ์ wrote:

> Hello,
>
> I plan to use Octave in my control theory classroom. However, I found some
> strange problems while trying to simulate DC motor with PI controller.
> Function bode() does not work even it should be. Now, I am using Octave
> 2.1.50a on Win2k downloaded from octave.sf.net. May someone please explain
> how to solve this problem?
>
> Thank you in advance
> Supachai
>
>  
>
> > > motor = tf2sys([4500],[1 361.2 0]);
> > > PI = tf2sys([1 0.1],[1 0]);
> > > G = sysmult(motor,PI);
> > >      
> warning: in
> /opt/octave/share/octave/2.1.50/m/control/system/__sysgroupn__.m near line
> 44, column 9:
>
>  
>
> > > > warning ("sysgroup: %s name(%d) = %s name(%d) = %s", kind, ii, kind,
> > > >        
> jj, st1);
>
>
> warning: sysgroup: state name(1) = state name(3) = x_1
> warning: sysgroup:     changed state name 3 to x_1_3
>  
>
>
>
>
>
>  
Here is how I do it.
Doug Stewart


% motor = tf2sys([4500],[1 361.2 0]);
% PI = tf2sys([1 0.1],[1 0]);
% G = sysmult(motor,PI);


%Motor
mn=4500;
md=[1 361.2 0]

%PI
pin=[1 0.1]
pid=[1 0]

% multiply both numerators
gn=conv(pin,mn)

% multiply both denominators
gd=conv(pid,md)

%form the closed loop of a unity feedback system
nc=gn
dc=addpoly(gd,gn)


sysc=tf2sys(nc,dc)
sysout(sysc)

y=step(sysc)





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