nass-metrology-test-bench/index.org

Cercalo Test Bench

• Identification of the Plant

Identification of the Plant

  fs = 1e4;
  Ts = 1/fs;

We generate white noise with the "random number" simulink block, and we filter that noise.

  Gi = (1)/(1+s/2/pi/100);

  c2d(Gi, Ts, 'tustin')

c2d(Gi, Ts, 'tustin')

ans =

  0.030459 (z+1)
  --------------
    (z-0.9391)

Sample time: 0.0001 seconds
Discrete-time zero/pole/gain model.

  load('mat/data_001.mat', 't', 'ux')

  figure; plot(t, ux)

  [tf_est, freqs] = tfestimate(ux, yx, hanning(ceil(length(ux)/10)), [], [], fs);

  % h = idfrd(tf_est, freqs*2*pi, Ts);

figure;
ax1 = subplot(2, 1, 1);
hold on;
plot(freqs, abs(tf_est),'--')
set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log');
ylabel('Amplitude [m/N]');
hold off;

ax2 = subplot(2, 1, 2);
hold on;
plot(freqs, mod(180+180/pi*phase(tf_est), 360)-180,'--')
set(gca,'xscale','log');
ylim([-180, 180]);
yticks([-180, -90, 0, 90, 180]);
xlabel('Frequency [$Hz$]'); ylabel('Phase [deg]');
hold off;