Lsim not plotting anything

I'm working on simulating a linear dynamical system with both and LQR and an h-infinity controller. With LQR I've gotten it to work and simulated the output, but with my h-infinity setup, when I run the system, there is no plotted output. The matrix dimensions are correct, and the A and C matrices are non-empty (Bcl and Dcl are zeros, but it should still be able to simulate the system).

%% Simulations with H Infinity Controller
sys = ss(Acl,Bcl,Ccl,Dcl);
sys.OutputName = 'θ';

t1 = 0:0.05:15;
x1 = [0 0.5 -0.5 0 0 0 0 0.5 -0.5 0 0 0];
figure(1);
w1 = zeros(length(t1),1);
w(t1>1)=1;
lsim(sys,w1,t1,x1);
title('Small Initial Conditions with Controller');
grid on;

[Nader Babar]

Comparing this to when I simulate the system with a different controller:

sys2 = ss(A-B*K1,[],C,0);
sys2.OutputName = 'θ';

t3 = 0:0.05:15;
x3 = [0 0.05 -0.05 0 0 0];
figure(1);
u3 = zeros(length(t3),1);
lsim(sys2,u3,t3,x3);
title('Small Initial Conditions with Controller');
grid on;

Answer 1

[Venkat Siddarth]

Hi @Nader Babar,

In the script you have mentioned.I noticed that the variable w1 was passed to the lsim function, which was a zero matrix and therefore not modified. However, I suspect that there may be an error in the code where w was mistaken for w1 in the following line, which should be changing the variable's value.

Please refer to the following code snippet for an illustration:

w1 = zeros(length(t1),1);    %%------------>Zero Matrix
w(t1>1)=1;
lsim(sys,w1,t1,x1); %% -----------------> % w1 not modified

I hope this resolves the issue

Regards

Venkat Siddarth V.