keep getting Index exceeds matrix dimensions.

x=[];
ES=[];
kt=140;
kv=140;
L=0.001;
R=10;
b=5;
J=8.6;
kp=240;
ki=180;
A=[0 1 0 0;0 -b/J kt/J 0;-kp/L -kv/L -R/L ki/L;-1 0 0 0]; 
B=[0;0;kp/L;1];
C=[-1 0 0 0];
D=1;
x0=[30;0;0;0];
sys=ss(A,B,C,D);
for i=1:89
    sunTime2(i)=(i-1)*1800;
end
 
lsim(sys,sunElevation2,sunTime2,x0);
plot(x(1,:));

for i=1:89
    ES(i+1)=ES(i)+x(3,i)*(kp*(sunElevation2(i)-x(1,i))+ki*x(4,i));
end;
plot(ES);

The 2nd for loop has an Index that exceeds matrix dimensions.

My purpose is to calculate the Enrgy spent.

I'd appreciate your help with finding the problem.

thanks,

Daniel

[Rik]

lsim(sys,sunElevation2,sunTime2,x0);

Unrecognized function or variable 'sunElevation2'.

Also, what have you tried so far? Did you try using the debugger to determine the size and shape of your variables? Did they match your expectation?

Answer 1

[KSSV]

The error is clear.....you are trying to extract more number of elements than present from an array.

EXample:

A = rand(1,5) ; 
A(1) % no error
A(5) % no error
A(6)  % error because there are only 5 elements in A and you are extracting 6th element 
A(2,1)  % error, Rememeber A is a row matrix not a column matrix 

Like wise, in you variables from the line:

ES(i+1)=ES(i)+x(3,i)*(kp*(sunElevation2(i)-x(1,i))+ki*x(4,i));

check the dimensions of Es, x, sunElevation. Do they have any dimension of 89? Is x of dimension 4*89?

Did you define Es and initialize it?

The best way to check is learn debugging.