state space into transformer function ......where is the problem
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clear all, close all, clc;
syms f j k1 k R l
%% State space representation
A = [-f/j k1/j;(-k-k1)/l -R/l];
% the state matrix
B = [0 -1/j;k/j 0];
% the input vector
C = [1 0;0 1];
% the output vector
D = zeros(size(C,2),size(B,2));
% the feedforward
%% Verify the controllability and observability
Mc = ctrb(A,B);
% Controllability matrix
Om = obsv(A,C)
% matrix
the_means_not_controllable = length(A)-length(Mc)
if rank(Mc) == size(A,2)
'It is controllable'
else
'It is not controllable'
end
if rank(Om) == size(A,2)
'It is observable'
else
'It is not observable'
end
%% Transform into transfer function
[num,den] = ss2tf(A,B,C,D)
sys = tf(num,den)
%Order system
Order_system = order(sys)
step(sys,'g')
grid on
.................................................................the problem
Error using ctrb (line 20)
The "ctrb" command cannot be used for models of class "sym".
Error in state_space (line 19)
Mc = ctrb(A,B);
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Answers (1)
Pavl M.
on 30 Nov 2024 at 13:40
I found and corrected it:
clear all, close all, clc;
syms f j k1 k R l
%% State space representation
A = [-f/j k1/j;(-k-k1)/l -R/l];
% the state matrix
B = [0 -1/j;k/j 0];
% the input vector
C = [1 0;0 1];
% the output vector
D = zeros(size(C,2),size(B,2));
A = double(subs(A,{f,j,k1,k,R,l},{1,2,3,4,5,6}))
B = double(subs(B,{j,k},{2,4}))
% the feedforward
%% Verify the controllability and observability
Mc = ctrb(A,B);
% Controllability matrix
Om = obsv(A,C)
% matrix
the_means_not_controllable = length(A)-length(Mc)
if rank(Mc) == size(A,2)
'It is controllable'
else
'It is not controllable'
end
if rank(Om) == size(A,2)
'It is observable'
else
'It is not observable'
end
%% Transform into transfer function
[num,den] = ss2tf(A,B,C,D,1)
sys1 = tf(num(1,:),den)
sys2 = tf(num(2,:),den)
%Order system
Order_system1 = order(sys1)
Order_system2 = order(sys2)
step(sys1,'g')
hold on
grid on
step(sys2,'b')
grid on
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