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Test Bench APA95ML

• Introduction
• Setup
  • Parameters
  • Filter White Noise
• Run Experiment and Save Data
  • Load Data
  • Save Data
• Huddle Test
  • Time Domain Data
  • PSD of Measurement Noise
• Transfer Function Estimation with $m=5kg$
  • Time Domain Data
  • Comparison of the PSD with Huddle Test
  • Compute TF estimate and Coherence
  • Comparison with the FEM model

Introduction   ignore

Picture of the Setup

Zoom on the APA

Setup

Parameters

  Ts = 1e-4;

Filter White Noise

  Glpf = 1/(1 + s/2/pi/500);

  Gz = c2d(Glpf, Ts, 'tustin');

Run Experiment and Save Data

Load Data

  data = SimulinkRealTime.utils.getFileScopeData('data/apa95ml.dat').data;

Save Data

  u = data(:, 1); % Input Voltage [V]
  y = data(:, 2); % Output Displacement [m]
  t = data(:, 3); % Time [s]

  save('./mat/huddle_test.mat', 't', 'u', 'y', 'Glpf');

Huddle Test

Time Domain Data

Measurement of the Mass displacement during Huddle Test

PSD of Measurement Noise

  Ts = t(end)/(length(t)-1);
  Fs = 1/Ts;
 
  win = hanning(ceil(1*Fs));

  [pxx, f] = pwelch(y, win, [], [], Fs);

Amplitude Spectral Density of the Displacement during Huddle Test

Transfer Function Estimation with $m=5kg$

Time Domain Data

Time domain signals during the test

Comparison of the PSD with Huddle Test

  Ts = t(end)/(length(t)-1);
  Fs = 1/Ts;

  win = hanning(ceil(1*Fs));

  [pxx, f] = pwelch(y, win, [], [], Fs);
  [pht, ~] = pwelch(ht.y, win, [], [], Fs);

Comparison of the ASD for the identification test and the huddle test

Compute TF estimate and Coherence

  win = hann(ceil(1/Ts));

  [tf_est, f] = tfestimate(u, -y, win, [], [], 1/Ts);
  [co_est, ~] = mscohere(  u, -y, win, [], [], 1/Ts);

Coherence

Estimation of the transfer function from input voltage to displacement

Comparison with the FEM model

  load('mat/fem_model_5kg.mat', 'Ghm');

Comparison of the identified transfer function and the one estimated from the FE model