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<h1 class="title">Test Bench APA95ML</h1>
<div id="table-of-contents">
<h2>Table of Contents</h2>
<div id="text-table-of-contents">
<ul>
<li><a href="#org6c2cfcc">1. Setup</a>
<ul>
<li><a href="#org9e42c6d">1.1. Parameters</a></li>
<li><a href="#org8bb3ebf">1.2. Filter White Noise</a></li>
</ul>
</li>
<li><a href="#org229c57e">2. Run Experiment and Save Data</a>
<ul>
<li><a href="#org79522ee">2.1. Load Data</a></li>
<li><a href="#org050454c">2.2. Save Data</a></li>
</ul>
</li>
<li><a href="#org178348e">3. Huddle Test</a>
<ul>
<li><a href="#org7eb915d">3.1. Time Domain Data</a></li>
<li><a href="#org959048f">3.2. PSD of Measurement Noise</a></li>
</ul>
</li>
<li><a href="#org4742221">4. Transfer Function Estimation using the DAC as the driver</a>
<ul>
<li><a href="#org3d81de2">4.1. Time Domain Data</a></li>
<li><a href="#org39e0140">4.2. Comparison of the PSD with Huddle Test</a></li>
<li><a href="#org8b00bfb">4.3. Compute TF estimate and Coherence</a></li>
<li><a href="#orgbf49872">4.4. Comparison with the FEM model</a></li>
</ul>
</li>
<li><a href="#orga133ef0">5. Transfer Function Estimation using the PI Amplifier</a>
<ul>
<li><a href="#orgb86aac7">5.1. Load Data</a></li>
<li><a href="#orgf221216">5.2. Comparison of the PSD with Huddle Test</a></li>
<li><a href="#orgeb0ef60">5.3. Compute TF estimate and Coherence</a></li>
<li><a href="#orgc786d54">5.4. Comparison with the FEM model</a></li>
</ul>
</li>
<li><a href="#org7363765">6. Transfer function from force actuator to force sensor</a>
<ul>
<li><a href="#org5ad8bf1">6.1. System Identification</a></li>
<li><a href="#orgf1d7d77">6.2. Integral Force Feedback</a></li>
</ul>
</li>
<li><a href="#orgabc1447">7. IFF Tests</a>
<ul>
<li><a href="#org8a1d06a">7.1. First tests with few gains</a></li>
<li><a href="#org1241f3d">7.2. Second test with many Gains</a></li>
</ul>
</li>
</ul>
</div>
</div>
<div id="org0b2119e" class="figure">
<p><img src="figs/setup_picture.png" alt="setup_picture.png" />
</p>
<p><span class="figure-number">Figure 1: </span>Picture of the Setup</p>
</div>
<div id="org0256fb0" class="figure">
<p><img src="figs/setup_zoom.png" alt="setup_zoom.png" />
</p>
<p><span class="figure-number">Figure 2: </span>Zoom on the APA</p>
</div>
<div id="outline-container-org6c2cfcc" class="outline-2">
<h2 id="org6c2cfcc"><span class="section-number-2">1</span> Setup</h2>
<div class="outline-text-2" id="text-1">
</div>
<div id="outline-container-org9e42c6d" class="outline-3">
<h3 id="org9e42c6d"><span class="section-number-3">1.1</span> Parameters</h3>
<div class="outline-text-3" id="text-1-1">
<div class="org-src-container">
<pre class="src src-matlab">Ts = 1e-4;
</pre>
</div>
</div>
</div>
<div id="outline-container-org8bb3ebf" class="outline-3">
<h3 id="org8bb3ebf"><span class="section-number-3">1.2</span> Filter White Noise</h3>
<div class="outline-text-3" id="text-1-2">
<div class="org-src-container">
<pre class="src src-matlab">Glpf = 1/(1 + s/2/pi/500);
Gz = c2d(Glpf, Ts, 'tustin');
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-org229c57e" class="outline-2">
<h2 id="org229c57e"><span class="section-number-2">2</span> Run Experiment and Save Data</h2>
<div class="outline-text-2" id="text-2">
</div>
<div id="outline-container-org79522ee" class="outline-3">
<h3 id="org79522ee"><span class="section-number-3">2.1</span> Load Data</h3>
<div class="outline-text-3" id="text-2-1">
<div class="org-src-container">
<pre class="src src-matlab">data = SimulinkRealTime.utils.getFileScopeData('data/apa95ml.dat').data;
</pre>
</div>
</div>
</div>
<div id="outline-container-org050454c" class="outline-3">
<h3 id="org050454c"><span class="section-number-3">2.2</span> Save Data</h3>
<div class="outline-text-3" id="text-2-2">
<div class="org-src-container">
<pre class="src src-matlab">u = data(:, 1); % Input Voltage [V]
y = data(:, 2); % Output Displacement [m]
t = data(:, 3); % Time [s]
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">save('./mat/huddle_test.mat', 't', 'u', 'y', 'Glpf');
</pre>
</div>
</div>
</div>
</div>
<div id="outline-container-org178348e" class="outline-2">
<h2 id="org178348e"><span class="section-number-2">3</span> Huddle Test</h2>
<div class="outline-text-2" id="text-3">
</div>
<div id="outline-container-org7eb915d" class="outline-3">
<h3 id="org7eb915d"><span class="section-number-3">3.1</span> Time Domain Data</h3>
<div class="outline-text-3" id="text-3-1">
<div id="orgedb79ed" class="figure">
<p><img src="figs/huddle_test_time_domain.png" alt="huddle_test_time_domain.png" />
</p>
<p><span class="figure-number">Figure 3: </span>Measurement of the Mass displacement during Huddle Test</p>
</div>
</div>
</div>
<div id="outline-container-org959048f" class="outline-3">
<h3 id="org959048f"><span class="section-number-3">3.2</span> PSD of Measurement Noise</h3>
<div class="outline-text-3" id="text-3-2">
<div class="org-src-container">
<pre class="src src-matlab">Ts = t(end)/(length(t)-1);
Fs = 1/Ts;
win = hanning(ceil(1*Fs));
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">[pxx, f] = pwelch(y(1000:end), win, [], [], Fs);
</pre>
</div>
<div id="org4ad69f0" class="figure">
<p><img src="figs/huddle_test_pdf.png" alt="huddle_test_pdf.png" />
</p>
<p><span class="figure-number">Figure 4: </span>Amplitude Spectral Density of the Displacement during Huddle Test</p>
</div>
</div>
</div>
</div>
<div id="outline-container-org4742221" class="outline-2">
<h2 id="org4742221"><span class="section-number-2">4</span> Transfer Function Estimation using the DAC as the driver</h2>
<div class="outline-text-2" id="text-4">
<div class="important">
<p>
Results presented in this sections are wrong as the ADC cannot deliver enought current to the piezoelectric actuator.
</p>
</div>
</div>
<div id="outline-container-org3d81de2" class="outline-3">
<h3 id="org3d81de2"><span class="section-number-3">4.1</span> Time Domain Data</h3>
<div class="outline-text-3" id="text-4-1">
<div id="orgdf6c7aa" class="figure">
<p><img src="figs/apa95ml_5kg_10V_time_domain.png" alt="apa95ml_5kg_10V_time_domain.png" />
</p>
<p><span class="figure-number">Figure 5: </span>Time domain signals during the test</p>
</div>
</div>
</div>
<div id="outline-container-org39e0140" class="outline-3">
<h3 id="org39e0140"><span class="section-number-3">4.2</span> Comparison of the PSD with Huddle Test</h3>
<div class="outline-text-3" id="text-4-2">
<div class="org-src-container">
<pre class="src src-matlab">Ts = t(end)/(length(t)-1);
Fs = 1/Ts;
win = hanning(ceil(1*Fs));
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">[pxx, f] = pwelch(y, win, [], [], Fs);
[pht, ~] = pwelch(ht.y, win, [], [], Fs);
</pre>
</div>
<div id="org6c52ffe" class="figure">
<p><img src="figs/apa95ml_5kg_10V_pdf_comp_huddle.png" alt="apa95ml_5kg_10V_pdf_comp_huddle.png" />
</p>
<p><span class="figure-number">Figure 6: </span>Comparison of the ASD for the identification test and the huddle test</p>
</div>
</div>
</div>
<div id="outline-container-org8b00bfb" class="outline-3">
<h3 id="org8b00bfb"><span class="section-number-3">4.3</span> Compute TF estimate and Coherence</h3>
<div class="outline-text-3" id="text-4-3">
<div class="org-src-container">
<pre class="src src-matlab">Ts = t(end)/(length(t)-1);
Fs = 1/Ts;
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">win = hann(ceil(1/Ts));
[tf_est, f] = tfestimate(u, -y, win, [], [], 1/Ts);
[co_est, ~] = mscohere( u, -y, win, [], [], 1/Ts);
</pre>
</div>
<div id="org8bed71a" class="figure">
<p><img src="figs/apa95ml_5kg_10V_coh.png" alt="apa95ml_5kg_10V_coh.png" />
</p>
<p><span class="figure-number">Figure 7: </span>Coherence</p>
</div>
<div id="org80b2e97" class="figure">
<p><img src="figs/apa95ml_5kg_10V_tf.png" alt="apa95ml_5kg_10V_tf.png" />
</p>
<p><span class="figure-number">Figure 8: </span>Estimation of the transfer function from input voltage to displacement</p>
</div>
</div>
</div>
<div id="outline-container-orgbf49872" class="outline-3">
<h3 id="orgbf49872"><span class="section-number-3">4.4</span> Comparison with the FEM model</h3>
<div class="outline-text-3" id="text-4-4">
<div class="org-src-container">
<pre class="src src-matlab">load('mat/fem_model_5kg.mat', 'Ghm');
</pre>
</div>
<div id="orgc255f7f" class="figure">
<p><img src="figs/apa95ml_5kg_comp_fem.png" alt="apa95ml_5kg_comp_fem.png" />
</p>
<p><span class="figure-number">Figure 9: </span>Comparison of the identified transfer function and the one estimated from the FE model</p>
</div>
</div>
</div>
<div class="outline-text-2" id="text-4">
<div class="important">
<p>
The problem comes from the fact that the piezo is driven directly by the DAC that cannot deliver enought current.
In the next section, a current amplifier is used.
</p>
</div>
</div>
</div>
<div id="outline-container-orga133ef0" class="outline-2">
<h2 id="orga133ef0"><span class="section-number-2">5</span> Transfer Function Estimation using the PI Amplifier</h2>
<div class="outline-text-2" id="text-5">
</div>
<div id="outline-container-orgb86aac7" class="outline-3">
<h3 id="orgb86aac7"><span class="section-number-3">5.1</span> Load Data</h3>
<div class="outline-text-3" id="text-5-1">
<div class="org-src-container">
<pre class="src src-matlab">ht = load('./mat/huddle_test.mat', 't', 'u', 'y');
load('./mat/apa95ml_5kg_Amp_E505.mat', 't', 'u', 'um', 'y');
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">u = 10*(u - mean(u)); % Input Voltage of Piezo [V]
um = 10*(um - mean(um)); % Monitor [V]
y = y - mean(y); % Mass displacement [m]
ht.u = 10*(ht.u - mean(ht.u));
ht.y = ht.y - mean(ht.y);
</pre>
</div>
</div>
</div>
<div id="outline-container-orgf221216" class="outline-3">
<h3 id="orgf221216"><span class="section-number-3">5.2</span> Comparison of the PSD with Huddle Test</h3>
<div class="outline-text-3" id="text-5-2">
<div class="org-src-container">
<pre class="src src-matlab">Ts = t(end)/(length(t)-1);
Fs = 1/Ts;
win = hanning(ceil(1*Fs));
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">[pxx, f] = pwelch(y, win, [], [], Fs);
[pht, ~] = pwelch(ht.y, win, [], [], Fs);
</pre>
</div>
<div id="orgc3cf37d" class="figure">
<p><img src="figs/apa95ml_5kg_PI_pdf_comp_huddle.png" alt="apa95ml_5kg_PI_pdf_comp_huddle.png" />
</p>
<p><span class="figure-number">Figure 10: </span>Comparison of the ASD for the identification test and the huddle test</p>
</div>
</div>
</div>
<div id="outline-container-orgeb0ef60" class="outline-3">
<h3 id="orgeb0ef60"><span class="section-number-3">5.3</span> Compute TF estimate and Coherence</h3>
<div class="outline-text-3" id="text-5-3">
<div class="org-src-container">
<pre class="src src-matlab">Ts = t(end)/(length(t)-1);
Fs = 1/Ts;
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">win = hann(ceil(1/Ts));
[tf_est, f] = tfestimate(u, -y, win, [], [], 1/Ts);
[tf_um , ~] = tfestimate(um, -y, win, [], [], 1/Ts);
[co_est, ~] = mscohere( um, -y, win, [], [], 1/Ts);
</pre>
</div>
<div id="orgbf0faa3" class="figure">
<p><img src="figs/apa95ml_5kg_PI_coh.png" alt="apa95ml_5kg_PI_coh.png" />
</p>
<p><span class="figure-number">Figure 11: </span>Coherence</p>
</div>
<div id="org408425b" class="figure">
<p><img src="figs/apa95ml_5kg_PI_tf.png" alt="apa95ml_5kg_PI_tf.png" />
</p>
<p><span class="figure-number">Figure 12: </span>Estimation of the transfer function from input voltage to displacement</p>
</div>
</div>
</div>
<div id="outline-container-orgc786d54" class="outline-3">
<h3 id="orgc786d54"><span class="section-number-3">5.4</span> Comparison with the FEM model</h3>
<div class="outline-text-3" id="text-5-4">
<div class="org-src-container">
<pre class="src src-matlab">load('mat/fem_model_5kg.mat', 'G');
</pre>
</div>
<div id="org5c02e5d" class="figure">
<p><img src="figs/apa95ml_5kg_pi_comp_fem.png" alt="apa95ml_5kg_pi_comp_fem.png" />
</p>
<p><span class="figure-number">Figure 13: </span>Comparison of the identified transfer function and the one estimated from the FE model</p>
</div>
</div>
</div>
</div>
<div id="outline-container-org7363765" class="outline-2">
<h2 id="org7363765"><span class="section-number-2">6</span> Transfer function from force actuator to force sensor</h2>
<div class="outline-text-2" id="text-6">
<p>
Two measurements are performed:
</p>
<ul class="org-ul">
<li>Speedgoat DAC =&gt; Voltage Amplifier (x20) =&gt; 1 Piezo Stack =&gt; &#x2026; =&gt; 2 Stacks as Force Sensor (parallel) =&gt; Speedgoat ADC</li>
<li>Speedgoat DAC =&gt; Voltage Amplifier (x20) =&gt; 2 Piezo Stacks (parallel) =&gt; &#x2026; =&gt; 1 Stack as Force Sensor =&gt; Speedgoat ADC</li>
</ul>
<p>
The obtained dynamics from force actuator to force sensor are compare with the FEM model.
</p>
<p>
The data are loaded:
</p>
<div class="org-src-container">
<pre class="src src-matlab">a_ss = load('mat/apa95ml_5kg_1a_2s.mat', 't', 'u', 'y', 'v');
aa_s = load('mat/apa95ml_5kg_2a_1s.mat', 't', 'u', 'y', 'v');
load('mat/G_force_sensor_5kg.mat', 'G');
</pre>
</div>
<p>
Let&rsquo;s use the amplifier gain to obtain the true voltage applied to the actuator stack(s)
</p>
<p>
The parameters of the piezoelectric stacks are defined below:
</p>
<div class="org-src-container">
<pre class="src src-matlab">d33 = 3e-10; % Strain constant [m/V]
n = 80; % Number of layers per stack
eT = 1.6e-8; % Permittivity under constant stress [F/m]
sD = 2e-11; % Elastic compliance under constant electric displacement [m2/N]
ka = 235e6; % Stack stiffness [N/m]
</pre>
</div>
<p>
From the FEM, we construct the transfer function from DAC voltage to ADC voltage.
</p>
<div class="org-src-container">
<pre class="src src-matlab">Gfem_aa_s = exp(-s/1e4)*20*(2*d33*n*ka)*(G(3,1)+G(3,2))*d33/(eT*sD*n);
Gfem_a_ss = exp(-s/1e4)*20*( d33*n*ka)*(G(3,1)+G(2,1))*d33/(eT*sD*n);
</pre>
</div>
<p>
The transfer function from input voltage to output voltage are computed and shown in Figure <a href="#org819df41">14</a>.
</p>
<div class="org-src-container">
<pre class="src src-matlab">Ts = a_ss.t(end)/(length(a_ss.t)-1);
Fs = 1/Ts;
win = hann(ceil(10/Ts));
[tf_a_ss, f] = tfestimate(a_ss.u, a_ss.v, win, [], [], 1/Ts);
[coh_a_ss, ~] = mscohere( a_ss.u, a_ss.v, win, [], [], 1/Ts);
[tf_aa_s, f] = tfestimate(aa_s.u, aa_s.v, win, [], [], 1/Ts);
[coh_aa_s, ~] = mscohere( aa_s.u, aa_s.v, win, [], [], 1/Ts);
</pre>
</div>
<div id="org819df41" class="figure">
<p><img src="figs/bode_plot_force_sensor_voltage_comp_fem.png" alt="bode_plot_force_sensor_voltage_comp_fem.png" />
</p>
<p><span class="figure-number">Figure 14: </span>Comparison of the identified dynamics from voltage output to voltage input and the FEM</p>
</div>
</div>
<div id="outline-container-org5ad8bf1" class="outline-3">
<h3 id="org5ad8bf1"><span class="section-number-3">6.1</span> System Identification</h3>
<div class="outline-text-3" id="text-6-1">
<div class="org-src-container">
<pre class="src src-matlab">w_z = 2*pi*111; % Zeros frequency [rad/s]
w_p = 2*pi*255; % Pole frequency [rad/s]
xi_z = 0.05;
xi_p = 0.015;
G_inf = 2;
Gi = G_inf*(s^2 - 2*xi_z*w_z*s + w_z^2)/(s^2 + 2*xi_p*w_p*s + w_p^2);
</pre>
</div>
<div id="orgc283618" class="figure">
<p><img src="figs/iff_plant_identification_apa95ml.png" alt="iff_plant_identification_apa95ml.png" />
</p>
<p><span class="figure-number">Figure 15: </span>Identification of the IFF plant</p>
</div>
</div>
</div>
<div id="outline-container-orgf1d7d77" class="outline-3">
<h3 id="orgf1d7d77"><span class="section-number-3">6.2</span> Integral Force Feedback</h3>
<div class="outline-text-3" id="text-6-2">
<div id="org6524816" class="figure">
<p><img src="figs/root_locus_iff_apa95ml_identification.png" alt="root_locus_iff_apa95ml_identification.png" />
</p>
<p><span class="figure-number">Figure 16: </span>Root Locus for IFF</p>
</div>
</div>
</div>
</div>
<div id="outline-container-orgabc1447" class="outline-2">
<h2 id="orgabc1447"><span class="section-number-2">7</span> IFF Tests</h2>
<div class="outline-text-2" id="text-7">
</div>
<div id="outline-container-org8a1d06a" class="outline-3">
<h3 id="org8a1d06a"><span class="section-number-3">7.1</span> First tests with few gains</h3>
<div class="outline-text-3" id="text-7-1">
<div class="org-src-container">
<pre class="src src-matlab">iff_g10 = load('./mat/apa95ml_iff_g10_res.mat', 'u', 't', 'y', 'v');
iff_g100 = load('./mat/apa95ml_iff_g100_res.mat', 'u', 't', 'y', 'v');
iff_of = load('./mat/apa95ml_iff_off_res.mat', 'u', 't', 'y', 'v');
</pre>
</div>
<div class="org-src-container">
<pre class="src src-matlab">Ts = 1e-4;
win = hann(ceil(10/Ts));
[tf_iff_g10, f] = tfestimate(iff_g10.u, iff_g10.y, win, [], [], 1/Ts);
[co_iff_g10, ~] = mscohere(iff_g10.u, iff_g10.y, win, [], [], 1/Ts);
[tf_iff_g100, f] = tfestimate(iff_g100.u, iff_g100.y, win, [], [], 1/Ts);
[co_iff_g100, ~] = mscohere(iff_g100.u, iff_g100.y, win, [], [], 1/Ts);
[tf_iff_of, ~] = tfestimate(iff_of.u, iff_of.y, win, [], [], 1/Ts);
[co_iff_of, ~] = mscohere(iff_of.u, iff_of.y, win, [], [], 1/Ts);
</pre>
</div>
<div id="orgbc64698" class="figure">
<p><img src="figs/iff_first_test_coherence.png" alt="iff_first_test_coherence.png" />
</p>
<p><span class="figure-number">Figure 17: </span>Coherence</p>
</div>
<div id="org16a4139" class="figure">
<p><img src="figs/iff_first_test_bode_plot.png" alt="iff_first_test_bode_plot.png" />
</p>
<p><span class="figure-number">Figure 18: </span>Bode plot for different values of IFF gain</p>
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</div>
</div>
<div id="outline-container-org1241f3d" class="outline-3">
<h3 id="org1241f3d"><span class="section-number-3">7.2</span> Second test with many Gains</h3>
<div class="outline-text-3" id="text-7-2">
<div class="org-src-container">
<pre class="src src-matlab">load('./mat/apa95ml_iff_test.mat', 'results');
</pre>
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<div class="org-src-container">
<pre class="src src-matlab">Ts = 1e-4;
win = hann(ceil(10/Ts));
</pre>
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<div class="org-src-container">
<pre class="src src-matlab">tf_iff = {zeros(1, length(results))};
co_iff = {zeros(1, length(results))};
g_iff = [0, 1, 5, 10, 50, 100];
for i=1:length(results)
[tf_est, f] = tfestimate(results{i}.u, results{i}.y, win, [], [], 1/Ts);
[co_est, ~] = mscohere(results{i}.u, results{i}.y, win, [], [], 1/Ts);
tf_iff(i) = {tf_est};
co_iff(i) = {co_est};
end
</pre>
</div>
<div id="orgcc7302c" class="figure">
<p><img src="figs/iff_results_bode_plots.png" alt="iff_results_bode_plots.png" />
</p>
</div>
<div class="org-src-container">
<pre class="src src-matlab">G_id = {zeros(1,length(results))};
f_start = 70; % [Hz]
f_end = 500; % [Hz]
for i = 1:length(results)
tf_id = tf_iff{i}(sum(f&lt;f_start):length(f)-sum(f&gt;f_end));
f_id = f(sum(f&lt;f_start):length(f)-sum(f&gt;f_end));
gfr = idfrd(tf_id, 2*pi*f_id, Ts);
G_id(i) = {procest(gfr,'P2UDZ')};
end
</pre>
</div>
<div id="org435aaa6" class="figure">
<p><img src="figs/iff_results_bode_plots_identification.png" alt="iff_results_bode_plots_identification.png" />
</p>
</div>
<div id="org9db1293" class="figure">
<p><img src="figs/iff_results_root_locus.png" alt="iff_results_root_locus.png" />
</p>
</div>
</div>
</div>
</div>
</div>
<div id="postamble" class="status">
<p class="author">Author: Dehaeze Thomas</p>
<p class="date">Created: 2020-08-21 ven. 15:26</p>
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