error in ss2tf when modelling a DC motor

hello guys,

i am getting error when i try to run it. it says " The B and D matrices must have the same number of columns."

%motor parameters

Km = 50.2*10^-3; % NM/A

Kb = (1/(190*2*pi/60)); %or V/Wm (wm in rps) volt/rps

Jm =11.6 *10^-7; %kgm^2

Bm = ((50.2*10^-3)*(20*10^-3)/(9080*2*pi/60));

R =10.6; %ohm

L = .82*10^-3;% H(henry)

%state space model

A = [-R/L -Kb/L ;Km/Jm -Bm/Jm ];

B = [1/L 0 ;0 -1/Jm ];

C = [0 1];

D = 0;

%state space

Motor_ss = ss(A,B,C,D);

[num_omega, dem_omega] = ss2tf(A,B,C,D);

can someone identify whats wrong with this code?

[Star Strider]

Please post your original model equations, or a PDF or an image of them.

[Avinash Tallapaneni]

i have inserted final model equation...

Answer 1

[Xu Da]

Hi, Tallapaneni

You have got the error B value. It shoud be like that

B = [1/L ; -1/Jm ]