Modeling PMDC Motor & Mechanical System

[Quadruple Bypass]

alright I've got to model a PMDC motor and a mechanical system attached to it

this is what i have so far for the equations part, which is where the problem is (im trying to graph the time histories of the 3 DE's)

function Xdot=project(t,X)
global R L km B J M b k r

V=10; % step function: 10 Volts

% State equations (1st order differential equations)
% X(1) = theta = angular displacement of pinion
% X(2) = theta dot = angular velocity of pinion
% X(3) = I = current
% X(4) = I dot

Xdot1= X(2);
Xdot2= (1/(J-M*r^2))*(-B*X(2)+km*X(3)+b*r^2*X(2)+k*r^2*X(1));
Xdot3= (V-R*X(3)-km*X(2))/L;

% The differential equations must be put in a column vector
Xdot=[Xdot1; Xdot2; Xdot3];

the bolded part is where the problem is. if i substitute it for a constant number, say 10, the graphs are good.

i suck at matlab, never understood it, I am confused, what do i do?

 

[Quadruple Bypass]

never mind, my mind kicked in in the clutch and i got it.

 

[oswaler]

As a scientist, it is important to understand and troubleshoot any issues that arise during the modeling process. First, it is important to identify the problem. In this case, it seems that the equations are not producing the desired results when graphed.

One possible solution is to check the units of the variables used in the equations. Make sure that all units are consistent and match the units used in the parameters. In addition, double check the equations themselves to ensure they are correctly written and include all necessary terms.

If the issue persists, it may be helpful to consult with a colleague or seek assistance from a more experienced programmer. It is also important to read through the documentation and resources available for the software being used, in this case, MATLAB.

Remember, modeling is an iterative process and it may take some trial and error to get the desired results. Don't be discouraged and keep working through the problem until a satisfactory solution is found.