Error using ss. How do i fix this?
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My current code is below. This is my error code:
Error using ss (line 345)
The values of the "a" and "b" properties must be matrices with the same number of rows.
Error in Project43 (line 33)
sys=ss(A,BS,Chead,D);
>>
I have tried everything I know how to do to fix it, but it is not working. Any suggestions?
m1=5.3;
m2=28.5;
m3=8.6;
m4=12.8;
c1=400;
c2=4750;
c3=4585;
c4=4475;
k1=310000;
k2=183000;
k3=162800;
k4=90000;
t=0:0.01:5;
A=[0 0 0 0 1 0 0 0; 0 0 0 0 0 1 0 0; 0 0 0 0 0 0 1 0; 0 0 0 0 0 0 0 1; -k1/m2 k1/m2 0 0 -c1/m2 c1/m2 0 0; k1/m2 -k1/m2 k2/m2 0 c1/m2 (-(c1/m2)-(c2/m2)) c2/m2 0; 0 k2/m3 (-(k2/m3)-(k3/m3)) k3/m3 0 c2/m3 (-(c2/m3)-(c3/m3)) c3/m3; 0 0 k3/m4 (-(k3/m3)-k4/m4) 0 0 c3/m4 (-(c3/m4)-(c4/m4))];
D=[0];
EV=eig(A);
dt=0.01;
tf=5;
t=0:dt:tf;
%for head displacement x1
Chead=[1 0 0 0 0 0 0 0];
%For Us
BS=[0 0 0 0 0 0 k4/m4 0];
sys=ss(A,BS,Chead,D);
[yS,t,x]= step(sys,t) ;
%For UI
BI=[0 0 0 0 0 0 0 c4/m4 ];
sys=ss(A,B,Chead,D);
[yI,t,x]= impulse(sys,t) ;
Yhead=yS+yI;
plot(t,Yhead)
% For torso displacement
Ctorso=[ 0 1 0 0 0 0 0 0];
%For Us
BS=[0 0 0 0 0 0 k4/m4 0];
sys=ss(A,BS,ctorso,D);
[yS,t,x]= step(sys,t) ;
%For UI
BI=[0 0 0 0 0 0 0 c4/m4 ];
sys=ss(A,BS,Ctorso,D);
[yI,t,x]= impulse(sys,t);
Yhead=yS+yI;
plot(t,Ytorso-Yhead)
%Repeat for head acceleration x1double dot using Cheadacc=[-k1/m1 k1/m1 0 0 –c1/m1 c1/m1 0 0] and plot(t,x1doubledot/9.81)
Cheadacc=[-k1/m1 k1/m1 0 0 -c1/m1 c1/m1 0 0];
%For Us
BS=[0 0 0 0 0 0 k4/m4 0];
sys=ss(A,BS,Cheadacc,D);
[yS,t,x]= step(sys,t);
%For UI
BI=[0 0 0 0 0 0 0 c4/m4 ];
sys=ss(A,BS,Cheadacc,D);
[yI,t,x]= impulse(sys,t) ;
Yhead=yS+yI;
plot(t,x1doubledot/9.81)
0 Comments
Accepted Answer
Star Strider
on 30 Jun 2020
Transpose ‘BS’ to a column vector (everywhere you use it, since you re-define it):
BS=[0 0 0 0 0 0 k4/m4 0].';
Do the same for ‘BI’.
There are a number of other problems and undefined variables. You need to solve those problems, since what you are doing is not obvious.
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