how to importing m-file with internal function to simulink? - matlab

Question

my problem is some hard to describe, but I try to express in the best.
I have a model with a main file by the name 'main.m' with some codes.
in 'main.m' file I used ode45 to solve differential equations.
here's my 'main.m' codes:
[t,x]=ode45(#vdp,[0 100],[0 0 -15 0]);
subplot(2,1,1);
plot(t,x(:,1),'r-',t,x(:,3),'b-');
title('Positions');
legend('Loco','Wagon');
xlabel('Time');
ylabel('Distance');
grid;
subplot(2,1,2);
plot(t,x(:,2),'r-',t,x(:,4),'b-');
title('Velocities');
legend('Loco','Wagon');
xlabel('Time');
ylabel('Velocity');
grid;
as you know, with ode45 we need a function to describe the differential equations and for this, I used another file by the name of 'vdp.m'.
my 'vdp.m' codes: Note that my input is "u" variable and outputs are "dx(1),dx(2),dx(3),dx(4)"?
function dx = vdp(t,x)
%% Setting Parameters
c0 = 7.6658*10^-3; % unit = Nkg^-1
cv = 1.08*10^-4; % unit = Ns(mkg)^-1
ca = 2.06*10^-5; % unit = Ns^2(m^2 kg)^-1
m1 = 50000; % unit = kg
m2 = 48500; % unit = kg
k1 = 85*10^2; % unit = Nm^-1
d1 = 85*10^4; % unit = kgs^-1
% Force Input
u = 3000; % unit = N 48750
%u2 = 0;
teta1 = 0;
teta2 = 0;
D1 = 0;
D2 = 0;
% dx=zeros(6,1); % a column vector
%% Generate Control Input
if t>=0 && t<=10
a=0;
u1=u*a;
elseif t>10 && t<=15
a=1;
u1=u*a;
elseif t>15 && t<=55
a=50;
u1=u*a;
elseif t>55 && t<=75
a=-97;
u1=u*a;
else
a=0;
u1=u*a;
end
%% State Equations
% x1 -> position of loco
% x2 -> velocity of loco
% x3 -> position of wagon
% x4 -> velocity of wagon
if t>=0 && t<=10
dx(1)=0; dx(2)=0; dx(3)=0; dx(4)=0;
dx = [dx(1);dx(2);dx(3);dx(4)];
elseif t>10 && t<=75
dx(1)=x(2);
dx(2)=(1/m1)*(u1-k1*(x(1)-x(3))-d1*(x(2)-x(4))-(c0+cv*x(2))*m1- ...
ca*((x(2))^2)*(m1+m2)-9.98*(sin(teta1))*m1-0.004*D1*m1);
dx(3)=x(4);
dx(4)=(1/m2)*(-k1*(x(3)-x(1))-d1*(x(4)-x(2))-(c0+cv*x(4))*m2- ...
9.98*(sin(teta2))*m2-0.004*D2*m2);
dx = [dx(1);dx(2);dx(3);dx(4)];
else
dx(1)=0; dx(2)=0; dx(3)=0; dx(4)=0;
dx = [dx(1);dx(2);dx(3);dx(4)];
end
Now I wanna use 'main.m' file program as a block in Simulink, because this codes are describing my model behavior.
Is there any way to import 'main.m' file to a block and use the block within my simulink model or a way to combining both two m-file to one file and making a function for using MATLAB Function Block?
Thanks all :)

Answer 1

I don't believe that you really want to do what your question says you want to do. Your main.m file is equivalent to the Simulink user interface, i.e. the bit where the solver and model run time (amongst other things) is specified. It doesn't make sense to want to use it within Simulink.
However, your second block of code, vdp, where the model functionality is defined, can certainly be used within Simulink. It (at least superficially) looks as if it can be dropped directly into a model using the MATLAB Function block. You'd feed its output (i.e. xdot) directly into a Continuous Time Integrator block, then feed the output of the integrator (which will be x) back into the second input of the MATLAB Function block. You'd feed a Clock block into the first input of the MATLAB Function block.
Of course you could also implement the vdp functionality using Simulink blocks rather than within m-code.