How to input two signals to one transfer function?

Hi,

I'm trying to simulate a dynamic model using matlab but I have problem with inputs to lsim function. There are two transfer functions (AM1 and AM2) and their output (f1 and f2) are input signals to the slider (that is a transfer function as well) which I don't know how to input them there.

clear;clc;

k=1.2; k0=1; ke=0.05; ke0=0.005; w=sqrt(12.177e6/0.10059); w0=sqrt(0.011e6/0.11613); miu=.3; k_s=0.5; d0=2;

T=5; Fs=5000; dt = 1/Fs; t = 0:dt:T-dt;

u1 = sawtooth(2*pi*t); %input signal1

u1 = (u1 + 1).*50;

AM1=tf([k*w^2],[1 2*ke*w w^2]);

y1=lsim(AM1,u1,t);

if y1<=d0

f1=0

else

f1=miu*k_s*(y1-d0);

end

u2 = sawtooth(2*pi*t+pi); %input signal2

u2 = (u2 + 1).*50;

AM2=tf([k*w^2],[1 2*ke*w w^2]);

y2=lsim(AM2,u2,t);

if y2<=d0

f2=0

else

f2=miu*k_s*(y2-d0);

end

slider=tf([k0*w0^2],[1 2*ke0*w0 w0^2]);

y3=lsim(slider,????,t); % f1 and f2 should be the inputs of this lsim function

Answer 1

[Paresh yeole]

I would suggest to create a state space system for the slider and then convert it to transfer function model.

While defining state space system make sure the B matrix has to columns (for two inputs).

Once you convert the state space system into transfer function model, use lsim as:

lsim(slider, [f1;f2], t)

I am sure there may be different ways, but this is what i could think of.