MATLAB: About why in pole placement gives me error

MATLABpole placement

Hi guys

Does every body knows why in the system :

s=tf('s');
G=(s-2.44)/((s+5)*(s+6)*(s+7));
[A,B,C,D]=tf2ss([1 2.44],[1 18 107 210]);
k_max=1001;
for j=1:k_max
    p(j,:)=[-j-1 -3*j -j-2];
    K(j,:)=place(A,B,p(j,:));
end

with differeing the p value it gives me this error?

Error using place (line 78)

The "place" command cannot place poles with multiplicity greater than rank(B).

Error in test2 (line 33)

K(j,:)=place(A,B,p(j,:));

Best Answer

It is just the error says. Place command cannot place poles with multiplicity greater than rank(B). In your case, rank(B) is 1. However when j=1, you want to place your poles at [-2 -3 -3]. You see the multiplicity of pole at -3 is 2. So place command cannot be used. If you start j from 2 instead of 1, there won't be an issue.

Related Solutions

MATLAB: >> R1=1; L=10e-3; C1=10e-6; R2=10; A=[-R1/L -1/L;1/C1 -1/(R2*C1)]; B=[1/L;0]; C=[0 1]; D=[0]; step(A,B,C,D),grid >> bode(A,B,C,D),grid ??? Error using ==> lti.bode at 95 Plots must be of the same type and size to be superimposed. Error in ==> bode

I do not get the error you see. Do you have a hold in between the step command and the bode command that you did not show here? It looks like you are trying to write the bode plot on the same axes as the step plot. Try this:

figure
step(A,B,C,D),grid
figure
bode(A,B,C,D),grid

This will plot the responses in separate figure windows.

Note also that this is a legacy syntax for step and bode; these commands are more powerful and flexible if you give them dynamic system input arguments:

sys = ss(A,B,C,D)
bode(sys)

MATLAB: I cant put the loop output in a matrix format. I want to put the loop output (p) as a vector or matrix in order to plot all the outputs later.

h=0.01;
dpdt= @(t,p) (kmax)*(1/(K+(1/p)));   % define K  and Kmax where is t here?
t=0:h:100;
p=zeros(1,numel(t));
p(1)=0.5;
for i=2:numel(t)
    k1=dpdt(t,p(i-1));
    k2=dpdt(t+(h/2), p(i-1)+(h*k1/2));
    k3=dpdt(t+(h/2), p(i-1)+(h*k2/2));
    k4=dpdt(t+h, p(i-1)+(h*k3));
    p(i)=p(i-1)+((1/6)*(k1+(2*k2)+(2*k3)+k4)*h);
end
plot(p,t)

Best Answer

Related Solutions

MATLAB: >> R1=1; L=10e-3; C1=10e-6; R2=10; A=[-R1/L -1/L;1/C1 -1/(R2*C1)]; B=[1/L;0]; C=[0 1]; D=[0]; step(A,B,C,D),grid >> bode(A,B,C,D),grid ??? Error using ==> lti.bode at 95 Plots must be of the same type and size to be superimposed. Error in ==> bode

MATLAB: I cant put the loop output in a matrix format. I want to put the loop output (p) as a vector or matrix in order to plot all the outputs later.

Related Question