Index exceeds the number of array elements (1) using transfer function

I don't understand what is wrong, it's frustrating.

% set up motor with initial conditions and properties
motor.timeConstant = 0.65;   % [min]
motor.gain = 0.5;            % [rpm/V]

% transfer function for the motor
s = tf('s');
TFmotor_OL = motor.gain / (motor.timeConstant*s +1); 

ERROR message:

>> Tutorial3controllingplant

Index exceeds the number of array elements (1).

Error in Tutorial3controllingplant (line 6)

s = tf('s');

Answer 1

[Amir RF]

Dear Lucy,

I run your code and I did not get any errors. Your error may be in your earlier code line (where you define s).

Best,

[Lucy Beksinska]

Thank you Amir!

This is all the code I have in this script, how do I define 's' for the TF?

[Amir RF]

You can replace

s = tf('s');
TFmotor_OL = motor.gain / (motor.timeConstant*s +1); 

with

TFmotor_OL = tf(motor.gain, [motor.timeConstant 1]);

This gives you the same result.

Best,

[Lucy Beksinska]

Thank you for your help. I have also restarted the MATLAB app and the error has gone!

regards, lucy