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Re: Problem in OCST

 From: Doug Stewart Subject: Re: Problem in OCST Date: Mon, 16 Feb 2004 16:24:37 -0500 User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.5) Gecko/20031007

```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
how to solve this problem?

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

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

y=step(sysc)

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```