DC motor current transfer function

Hello everybody, somebody bad at math here... Could somebody please give me a jumpstart on how the matrix should look like when wanting to calculate the current transfer function. In this example http://se.mathworks.com/help/control/getstart/linear-lti-models.html?requestedDomain=www.mathworks.com#f1-1010946 we find the angular velocity omega, but I would like to verify the validity of my work by finding the current aswell, given a voltage input. So far, ive not made any progress. Thank you for reading and bigger thank you if you could help me.

Answer 1

[Sebastian Castro]

If I understand your question correctly, the example you linked to has only a single output which is velocity; however you also want to output velocity.

If all you want to change is the output equation, then you only need to change the C and D matrices. For example, try changing them to:

% Current is first output, velocity is second output
C = [1 0;0 1];
D = [0;0];

or

% Velocity is first output, current is second output
C = [0 1;1 0];
D = [0;0];

Try this out. More importantly, make sure you actually understand what these modifications mean! Expand out the matrix equation y = C*x + D*u to verify that it is indeed doing the correct thing.

- Sebastian