Test Bench APA
+
+
+
+Table of Contents
+ +
+
+
+1 Parameters
+
+
+
+
+Ts = 1e-4; ++
+
+
+2 Filter White Noise
+
+
+
+
+Glpf = 1/(1 + s/2/pi/500); + +Gz = c2d(Glpf, Ts, 'tustin'); ++
+
+
+3 Load Data
+
+
+
+
+data = SimulinkRealTime.utils.getFileScopeData('data/apa95ml_5kg.dat').data;
+
+
+
+
+4 Time Domain Data
+
+
+
+
+figure;
+
+subplot(1,2,1);
+plot(data(:, 3), data(:, 1))
+ylabel('Input Voltage [V]'); xlabel('Time [s]');
+
+
+subplot(1,2,2);
+plot(data(:, 3), data(:, 2))
+ylabel('Output Displacement [m]'); xlabel('Time [s]');
+
+
+
+
+5 Compute TF estimate and Coherence
+
+
+
+
+win = hann(ceil(1/Ts)); + +[tf_est, f] = tfestimate(data(:, 1), -data(:, 2), win, [], [], 1/Ts); +[co_est, ~] = mscohere( data(:, 1), -data(:, 2), win, [], [], 1/Ts); ++
+
+
+6 Coherence
+
+
+
+
+figure;
+
+hold on;
+plot(f, co_est, 'k-')
+set(gca, 'Xscale', 'log'); set(gca, 'Yscale', 'lin');
+ylabel('Coherence'); xlabel('Frequency [Hz]');
+hold off;
+
+
+
+7 Transfer Function
+
+
+
+
+figure;
+ax1 = subplot(2, 1, 1);
+hold on;
+plot(f, abs(tf_est), 'k-')
+set(gca, 'Xscale', 'log'); set(gca, 'Yscale', 'log');
+ylabel('Amplitude'); xlabel('Frequency [Hz]');
+hold off;
+
+ax2 = subplot(2, 1, 2);
+hold on;
+plot(f, 180/pi*angle(tf_est), 'k-')
+set(gca, 'Xscale', 'log'); set(gca, 'Yscale', 'lin');
+ylabel('Phase'); xlabel('Frequency [Hz]');
+legend();
+hold off;
+
+linkaxes([ax1,ax2], 'x');
+xlim([10, 5000]);
+
+