MATLAB Answers

i have a problem ..help me

16 views (last 30 days)
belal hariz belgacem
belal hariz belgacem on 25 Oct 2019
Commented: Walter Roberson on 31 Oct 2019
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);

  3 Comments

belal hariz belgacem
belal hariz belgacem on 29 Oct 2019
The "ctrb" command cannot be used for models of class "sym".
Renato SL
Renato SL on 31 Oct 2019
from my experience with these functions, you don't need to declare the variables symbolically (no need for the line syms f j k k1 , etc) & you only need to assign the numeric values for all of the variables.
Walter Roberson
Walter Roberson on 31 Oct 2019
The Control System Toolbox does not support any symbolic parameters, for anything. There are some things that it support "tunable" parameters for, but at any given time a tunable parameter has a specific value.

Sign in to comment.

Answers (0)


Translated by