96 lines
2.3 KiB
Mathematica
96 lines
2.3 KiB
Mathematica
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%% Clear Workspace and Close figures
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clear; close all; clc;
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%% Intialize Laplace variable
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s = zpk('s');
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addpath('./mat/');
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% Load Data :ignore:
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% The data are loaded:
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load('apa95ml_5kg_2a_1s.mat', 't', 'u', 'v');
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% Any offset is removed.
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u = detrend(u, 0); % Speedgoat DAC output Voltage [V]
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v = detrend(v, 0); % Speedgoat ADC input Voltage (sensor stack) [V]
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% Here, the amplifier gain is 20.
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u = 20*u; % Actuator Stack Voltage [V]
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% Compute TF estimate and Coherence :ignore:
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% The transfer function from the actuator voltage $V_a$ to the force sensor stack voltage $V_s$ is computed.
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Ts = t(end)/(length(t)-1);
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Fs = 1/Ts;
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win = hann(ceil(5/Ts));
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[tf_est, f] = tfestimate(u, v, win, [], [], 1/Ts);
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[coh, ~] = mscohere( u, v, win, [], [], 1/Ts);
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% The coherence is shown in Figure [[fig:apa95ml_5kg_cedrat_coh]].
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figure;
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hold on;
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plot(f, coh, 'k-')
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set(gca, 'Xscale', 'log'); set(gca, 'Yscale', 'lin');
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ylabel('Coherence'); xlabel('Frequency [Hz]');
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hold off;
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xlim([10, 5e3]);
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% #+name: fig:apa95ml_5kg_cedrat_coh
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% #+caption: Coherence
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% #+RESULTS:
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% [[file:figs/apa95ml_5kg_cedrat_coh.png]]
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% The Simscape model is loaded and compared with the identified dynamics in Figure [[fig:bode_plot_force_sensor_voltage_comp_fem]].
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% The non-minimum phase zero is just a side effect of the not so great identification.
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% Taking longer measurements would results in a minimum phase zero.
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load('mat/fem_simscape_models.mat', 'Gfm');
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freqs = logspace(1, 4, 1000);
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figure;
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tiledlayout(3, 1, 'TileSpacing', 'None', 'Padding', 'None');
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ax1 = nexttile([2,1]);
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hold on;
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plot(f, abs(tf_est))
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plot(freqs, abs(squeeze(freqresp(Gfm, freqs, 'Hz'))))
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set(gca, 'Xscale', 'log'); set(gca, 'Yscale', 'log');
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ylabel('Amplitude [V/V]'); set(gca, 'XTickLabel',[]);
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hold off;
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ylim([1e-3, 1e1]);
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ax2 = nexttile;
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hold on;
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plot(f, 180/pi*angle(tf_est), ...
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'DisplayName', 'Identification')
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plot(freqs, 180/pi*angle(squeeze(freqresp(Gfm, freqs, 'Hz'))), ...
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'DisplayName', 'FEM')
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set(gca, 'Xscale', 'log'); set(gca, 'Yscale', 'lin');
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ylabel('Phase'); xlabel('Frequency [Hz]');
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hold off;
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ylim([-180, 180]);
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yticks(-180:90:180);
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legend('location', 'northeast')
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linkaxes([ax1,ax2], 'x');
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xlim([10, 5e3]);
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