the state representation of the dynamic system

clear all 
clc 
k=2; k1=0.5; L=0.02;
R=2; J=0.0005; f=0.00008;Cr=20;
A=[-f/J k1/J;(-k-k1)/L -R/L];
B=[0 -1/f;k/L 0];
C=[1 0;0 1];
x=[1;1];
D=[0];
t=0:0.1:7;
[x,y]= lsim(A,B,C,D,);

Error using lsim (line 105)

Wrong number of input arguments.

Error in Untitled (line 11)

[x,y]= lsim(A,B,C,D,t);

[Walter Roberson]

sys = ss(A, B, C, D);
[Y,T,X] = lsim(sys, U, t(:), x);

However this requires that you have a U array of inputs, that is length(t) x input channels, of inputs.Your system has two input channels so you might need x.' to make it into a row.