How do I solve "Error in port widths or dimensions" error in Simulink?

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[Ankit]

Hi Flavio,

your input to demux is a variable with 1 elements. How you are calculating your inputs or could you share some information about your logic inside subsystem block

VG

Ankit

[Flavio Clarizia]

Thanks for your answer. I have edited my question with more details.

[Ankit]

it is very hard to decifer, logic seems fine. Is it possible to just attached ".slx or mdl" v2018b ?

[Ankit]

try File --> Export Model to --> Previous Version -- 2018b

[Ankit]

great :) what are the values of k_1 and k_2 ? how have you defined them?

Answer 1

[Ankit]

function input = C_REG(q)


% global k_1 k_2

x=q(1);
y=q(2);
theta=q(3);

e_p=[-x -y];                    
sag=[cos(theta);sin(theta)];    
gamma=atan2(y,x)-theta+pi;      

% driving velocity 
v=k_1*e_p.*sag;

% steering velocity

omega=k_2*gamma;      

input = [v;omega];

you have to careful with matrix/vector multiplication. your e_p [1 x2 ] and sag [2x1] --> multiplication of e_p and sag gives a matrix of [2x2] and multiply with k1 [1] results in a vector of [1x2] --> driving velocity

and similarly omega is a scalar.

Could you please explain what is your expected output ? steering velocity vector or scalar.

and similary driving velocity?

[Flavio Clarizia]

I am expecting the linear aln angular velocity to be 2x1 vectors, since I want to drive the unicycle to the origin, so at (x,y)=(0,0).

Thanks again

[Ankit]

What is your problem now ? did you understand the difference between the two, % driving velocity

v=k_1*e_p*sag; and v=k_1*e_p.*sag; ?

[Flavio Clarizia]

Sorry i was answering the questions you posed. Thanks for the help.

[Ankit]

Hi no problem.

you have to correctly define your inputs.

I tried the following:

function [input1,input2] = C_REG(q)
global k_1 k_2
x=q(1);
y=q(2);
theta=q(3);
e_p=[-x -y];                    
sag=[cos(theta);sin(theta)];    
gamma=atan2(y,x)-theta+pi;      
% driving velocity 
v=k_1.*e_p.*sag;
% steering velocity
omega=k_2*gamma;      
input1 = v;
input2 = omega;

As I am not aware to your problem statement but you just need to see your sizes of inputs and outputs are correct!

omega is a scalar or vector?

as you see your v is a vector and omega is a scalar currently. You are not allowed to do the following

input = [v;omega]; % Dimensions of arrays being concatenated are not consistent so you will get an error.

[Ankit]

try this. as you mentioned your v and omega are scalar following will work. let me know if it is clear now?

function input = C_REG(q)
global k_1 k_2
x=q(1);
y=q(2);
theta=q(3);
e_p=[-x -y];                    
sag=[cos(theta);sin(theta)];    
gamma=atan2(y,x)-theta+pi;      
% driving velocity 
v=k_1*e_p*sag; % now it is scalar
% steering velocity
omega=k_2*gamma; % scalar 
input = [v;omega]; % it is allowed