When simulating the response to a specific input signal, the input data U must be a matrix with as many rows as samples in the time vector T

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Hi, this error is occurred.
Error using DynamicSystem/lsim
When simulating the response to a specific input signal, the input data U must be a matrix with as many rows as samples in the time vector T, and as many columns as input channels.
Error in untitleds (line 321)
[Responset_q_equi] = lsim(sysansq_equi , INPUT_equi , tempo);
I thought of solving by considering INPUT_equi as a 5-row vector, since the state space matrix B has 5 columns, and 1 column using function repmat but it doesn't work :( even considering the number of lines equal to that of the elements of the time vector does not work
This is the script (sysansq_equi is already defined in the previous part of the script that is not reported here)
%DEFINIZIONE ingressi nel tempo
%load(['Published/','accDX_equi_QUARTER_CAR.dat'])
INPUT_DX_equi_QUARTER_CAR = accDX_equi_QUARTER_CAR(:,2);
tempo = accDX_equi_QUARTER_CAR(:,1); % è uguale per ogni caso avendo ip. per ogni caso v = 4 m/s
% cioè 14.4 km/h
dt=mean(diff(tempo)); %calcola la media degli incrementi tra tempo(i) e tempo(i+1) per ogni i
Fmax=1/(2*dt); % Nyquist -- Fmax = Fc/2
%load(['Published/','accSX_equi_QUARTER_CAR.dat'])
%INPUT_SX_equi_QUARTER_CAR = accSX_equi_QUARTER_CAR(:,2);
max(accDX_equi_QUARTER_CAR(:,2))
%max(accSX_equi_QUARTER_CAR(:,2))
INPUT_equi = INPUT_DX_equi_QUARTER_CAR;
[Responset_q_equi] = lsim(sysansq_equi , INPUT_equi , tempo);
figure (9)
plot(tempo,Responset_q_equi)
xlabel('Tempo [s]')
ylabel('q')
grid on
legend('q1','q2','q3','q4','q5','q6','q7','q8','q9','q10')
title('Coordinate normali caso equiripartito')
p.s. sysansq_equi doesn't contain errors

Accepted Answer

Paul
Paul on 5 Aug 2022
Hi Federico,
If sysansq_equi.B has five columns then INPUT_equi must also have five columns. Also, the number of rows of INPUT_equi must be the same as numel(tempo). What are the outputs of the following commands:
size(sysansq_equi.B,2)
numel(tempo)
size(INPUT_equi)
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