nass-micro-station-measurements/Static/index.org

• Notes
• Data Pre-processing
• Matlab - Data Import
• Data - Plot
• Translate to time domain
• Compute the PSD

#+TITLE:Static Measurements

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Notes

• 5530: Straightness Plot: Yz
• Filename: r:\home\PDMU\PEL\Measurement_library\ID31\ID31_u_station\TY\12_12_2018\linear deviation _tyz_401_points.txt
• Acquisition date: 09/01/2019 13:49:42
• Current date: 08/03/2019 08:46:35
• Measurement Type: STRAIGHTNESS vertical
• Travel Mode: Bidirectional
• Number of Target Positions: 401
• Number of total data pairs: 2406
• Number of total data runs:6
• Position Value Units: millimeters
• Error Value Units: micrometers

Environmental Data	Min	Max	Avg
Air Temp (C)	024,57	024,61	024,59
Air Prs (mm)	742,56	743,29	742,83
Air Hmd (%)	024,00	024,00	024,00
MT1 Temp (C)			020,00
MT2 Temp (C)	024,40	024,44	024,42
MT3 Temp (C)	024,32	024,36	024,34

Data Pre-processing

  sed 's/\t/  /g;s/\,/./g' "data/linear deviation _tyz_401_points.txt" > data/data.txt

  head "data/data.txt"

Run	Pos	TargetValue	ErrorValue
1	1	-4.5E+00	7.5377892E+00
1	2	-4.4775E+00	7.5422246E+00
1	3	-4.455E+00	7.5655617E+00
1	4	-4.4325E+00	7.5149518E+00
1	5	-4.41E+00	7.4886377E+00
1	6	-4.3875E+00	7.437007E+00
1	7	-4.365E+00	7.4449354E+00
1	8	-4.3425E+00	7.3937387E+00
1	9	-4.32E+00	7.3287468E+00

Matlab - Data Import

  filename = 'data/data.txt';
  fileID = fopen(filename);
  data = cell2mat(textscan(fileID,'%f  %f  %f  %f', 'collectoutput', 1,'headerlines',1));
  fclose(fileID);

Data - Plot

  figure;
  hold on;
  for i=1:data(end, 1)
    plot(data(data(:, 1) == i, 3), data(data(:, 1) == i, 4), '-k');
  end
  hold off;
  xlabel('Target Value [mm]'); ylabel('Error Value [um]');

  <<plt-matlab>>

Time domain Data

Compute mean value of each position

  mean_pos = zeros(sum(data(:, 1)==1), 1);
  for i=1:sum(data(:, 1)==1)
    mean_pos(i) = mean(data(data(:, 2)==i, 4));
  end

  figure;
  hold on;
  for i=1:data(end, 1)
    filt = data(:, 1) == i;
    plot(data(filt, 3), data(filt, 4) - mean_pos, '-k');
  end
  hold off;
  xlabel('Target Value [mm]'); ylabel('Error Value [um]');

  <<plt-matlab>>

caption

Translate to time domain

  t = linspace(0, 1, length(data(data(:, 1)==1, 4)));

  figure;
  hold on;
  plot(t, data(data(:, 1) == 1, 4) - mean_pos, '-k');
  hold off;
  xlabel('Time [s]'); ylabel('Error Value [um]');

  <<plt-matlab>>

caption

Compute the PSD

  n_av = 5;
  Fs = 1/t(2);

  x = data(data(:, 1) == 1, 4) - mean_pos;
  [pxx, f] = pwelch(x, hanning(ceil(length(x)/n_av)), [], [], Fs);

  pxx_t = zeros(length(pxx), data(end, 1));

  for i=1:data(end, 1)
    x = data(data(:, 1) == i, 4) - mean_pos;
    [pxx, f] = pwelch(x, hanning(ceil(length(x)/n_av)), [], [], Fs);
    pxx_t(:, i) = pxx;
  end

  figure;
  hold on;
  plot(f, mean(pxx_t, 2));
  hold off;
  xlabel('Frequency (Hz)');
  ylabel('PSD ($m^2/Hz$)');
  set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log');
  legend({'PSD - x', 'PSD - y', 'PSD - z'});

  <<plt-matlab>>

PSD of the Z motion when scanning with Ty at 1Hz