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Identification

Table of Contents

The goal here is to make an identification of the micro-station in order to compare the model with the measurements on the real micro-station.

In order to do so:

For the excitation, we can choose the same excitation points as the one used for the modal test. For the measurement points, we can choose the Center of Mass of each solid body. The center of mass of each solid body is not easily defined using Simscape. Indeed, we can define the center of mass of any solid body but not of multiple solid bodies. However, one solid body is composed of multiple STEP files. One solution could be to use one STEP file for one solid body. However, the position of the center of mass can be exported using simulink and then defined on Simscape.

1 Identification of the Micro-Station

1.1 Compute the transfer functions

We first define some parameters for the identification. The simulink file for the identification is sim_micro_station_id.slx.

open('identification/matlab/sim_micro_station_id.slx')
%% Options for Linearized
options = linearizeOptions;
options.SampleTime = 0;

%% Name of the Simulink File
mdl = 'sim_micro_station_id';
%% Micro-Hexapod
% Input/Output definition
io(1) = linio([mdl, '/Micro-Station/Fm_ext'],1,'openinput');
io(2) = linio([mdl, '/Micro-Station/Fg_ext'],1,'openinput');
io(3) = linio([mdl, '/Micro-Station/Dm_inertial'],1,'output');
io(4) = linio([mdl, '/Micro-Station/Ty_inertial'],1,'output');
io(5) = linio([mdl, '/Micro-Station/Ry_inertial'],1,'output');
io(6) = linio([mdl, '/Micro-Station/Dg_inertial'],1,'output');
% Run the linearization
G_ms = linearize(mdl, io, 0);

% Input/Output names
G_ms.InputName  = {'Fmx', 'Fmy', 'Fmz',...
                   'Fgx', 'Fgy', 'Fgz'};
G_ms.OutputName = {'Dmx', 'Dmy', 'Dmz', ...
                   'Tyx', 'Tyy', 'Tyz', ...
                   'Ryx', 'Ryy', 'Ryz', ...
                   'Dgx', 'Dgy', 'Dgz'};
%% Save the obtained transfer functions
save('./mat/id_micro_station.mat', 'G_ms');

1.2 Plots the transfer functions

1.3 Compare with the measurements

2 Modal Analysis of the Micro-Station

2.1 Simscape Model

open('identification/matlab/sim_micro_station_modal_analysis.slx')
%% Options for Linearized
options = linearizeOptions;
options.SampleTime = 0;

%% Name of the Simulink File
mdl = 'sim_micro_station_modal_analysis';
%% Micro-Hexapod
% Input/Output definition
io(1) = linio([mdl, '/Micro-Station/F_hammer'],1,'openinput');
io(2) = linio([mdl, '/Micro-Station/acc9'],1,'output');
io(3) = linio([mdl, '/Micro-Station/acc10'],1,'output');
io(4) = linio([mdl, '/Micro-Station/acc11'],1,'output');
io(5) = linio([mdl, '/Micro-Station/acc12'],1,'output');
% Run the linearization
G_ms = linearize(mdl, io, 0);

% Input/Output names
G_ms.InputName  = {'Fx', 'Fy', 'Fz'};
G_ms.OutputName = {'x9', 'y9', 'z9', ...
                   'x10', 'y10', 'z10', ...
                   'x11', 'y11', 'z11', ...
                   'x12', 'y12', 'z12'};

2.2 Plot Results

figure;
hold on;
plot(freqs, abs(squeeze(freqresp(G_ms('x9', 'Fx'), freqs, 'Hz'))));
set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log');
ylabel('Amplitude [m/N]');
hold off;

2.3 Compare with measurements

load('../meas/modal-analysis/mat/frf_coh_matrices.mat', 'FRFs', 'COHs', 'freqs');
dirs = {'x', 'y', 'z'};

n_acc = 9;
n_dir = 1; % x, y, z
n_exc = 1; % x, y, z

figure;
hold on;
plot(freqs, abs(squeeze(FRFs(3*(n_acc-1) + n_dir, n_exc, :)))./((2*pi*freqs).^2)');
plot(freqs, abs(squeeze(freqresp(G_ms([dirs{n_dir}, num2str(n_acc)], ['F', dirs{n_dir}]), freqs, 'Hz'))));
set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log');
ylabel('Amplitude [m/N]');
hold off;

3 Compare with measurements at the CoM of each element

3.1 Init

initializeGround();
initializeGranite();
initializeTy();
initializeRy();
initializeRz();
initializeMicroHexapod();
initializeAxisc();

3.2 TODO Center of Mass of each solid body

  • [ ] Verify that this is coherent with the simscape and with the measurements
  granite bot granite top ty ry rz hexa
X [mm] 45 52 0 0 0 -4
Y [mm] 144 258 14 -5 0 6
Z [mm] -1251 -778 -600 -628 -580 -319
open('identification/matlab/sim_micro_station_modal_analysis_com.slx')

3.3 Simscape Model

%% Options for Linearized
options = linearizeOptions;
options.SampleTime = 0;

%% Name of the Simulink File
mdl = 'sim_micro_station_modal_analysis_com';
%% Micro-Hexapod
% Input/Output definition
io(1) = linio([mdl, '/Micro-Station/F_hammer'],1,'openinput');
io(2) = linio([mdl, '/Micro-Station/acc_gtop'],1,'output');
io(3) = linio([mdl, '/Micro-Station/acc_ty'],1,'output');
io(4) = linio([mdl, '/Micro-Station/acc_ry'],1,'output');
io(5) = linio([mdl, '/Micro-Station/acc_rz'],1,'output');
io(6) = linio([mdl, '/Micro-Station/acc_hexa'],1,'output');
% Run the linearization
G_ms = linearize(mdl, io, 0);

% Input/Output names
G_ms.InputName  = {'Fx', 'Fy', 'Fz'};
G_ms.OutputName = {'gtop_x', 'gtop_y', 'gtop_z', 'gtop_rx', 'gtop_ry', 'gtop_rz', ...
                   'ty_x', 'ty_y', 'ty_z', 'ty_rx', 'ty_ry', 'ty_rz', ...
                   'ry_x', 'ry_y', 'ry_z', 'ry_rx', 'ry_ry', 'ry_rz', ...
                   'rz_x', 'rz_y', 'rz_z', 'rz_rx', 'rz_ry', 'rz_rz', ...
                   'hexa_x', 'hexa_y', 'hexa_z', 'hexa_rx', 'hexa_ry', 'hexa_rz'};

3.4 Compare with measurements

load('../meas/modal-analysis/mat/frf_coh_matrices.mat', 'freqs');
load('../meas/modal-analysis/mat/frf_com.mat', 'FRFs_CoM');
dirs = {'x', 'y', 'z', 'rx', 'ry', 'rz'};
stages = {'gbot', 'gtop', 'ty', 'ry', 'rz', 'hexa'}

n_stg = 2;
n_dir = 5; % x, y, z, Rx, Ry, Rz
n_exc = 2; % x, y, z

f = logspace(0, 3, 1000);

figure;
hold on;
plot(freqs, abs(squeeze(FRFs_CoM(6*(n_stg-1) + n_dir, n_exc, :)))./((2*pi*freqs).^2)');
plot(f, abs(squeeze(freqresp(G_ms([stages{n_stg}, '_', dirs{n_dir}], ['F', dirs{n_exc}]), f, 'Hz'))));
set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log');
ylabel('Amplitude [m/N]');
hold off;
xlim([1, 200]);
dirs = {'x', 'y', 'z', 'rx', 'ry', 'rz'};
stages = {'gtop', 'ty', 'ry', 'rz', 'hexa'}

f = logspace(1, 3, 1000);

figure;
for n_stg = 1:2
  for n_dir = 1:3
    subplot(3, 2, (n_dir-1)*2 + n_stg);
    title(['F ', dirs{n_dir}, ' to ', stages{n_stg}, ' ', dirs{n_dir}]);
    hold on;
    plot(freqs, abs(squeeze(FRFs_CoM(6*(n_stg) + n_dir, n_dir, :)))./((2*pi*freqs).^2)');
    plot(f, abs(squeeze(freqresp(G_ms([stages{n_stg}, '_', dirs{n_dir}], ['F', dirs{n_dir}]), f, 'Hz'))));
    set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log');
    ylabel('Amplitude [m/N]');
    if n_dir == 3
      xlabel('Frequency [Hz]');
    end
    hold off;
    xlim([10, 1000]);
    ylim([1e-12, 1e-6]);
  end
end

identification_comp_bot_stages.png

Figure 1: caption (png, pdf)

dirs = {'x', 'y', 'z', 'rx', 'ry', 'rz'};
stages = {'ry', 'rz', 'hexa'}

f = logspace(1, 3, 1000);

figure;
for n_stg = 1:2
  for n_dir = 1:3
    subplot(3, 2, (n_dir-1)*2 + n_stg);
    title(['F ', dirs{n_dir}, ' to ', stages{n_stg}, ' ', dirs{n_dir}]);
    hold on;
    plot(freqs, abs(squeeze(FRFs_CoM(6*(n_stg+2) + n_dir, n_dir, :)))./((2*pi*freqs).^2)');
    plot(f, abs(squeeze(freqresp(G_ms([stages{n_stg}, '_', dirs{n_dir}], ['F', dirs{n_dir}]), f, 'Hz'))));
    set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log');
    ylabel('Amplitude [m/N]');
    if n_dir == 3
      xlabel('Frequency [Hz]');
    end
    hold off;
    xlim([10, 1000]);
    ylim([1e-12, 1e-6]);
  end
end

identification_comp_mid_stages.png

Figure 2: caption (png, pdf)

dirs = {'x', 'y', 'z', 'rx', 'ry', 'rz'};
stages = {'hexa'}

f = logspace(1, 3, 1000);

figure;
for n_stg = 1
  for n_dir = 1:3
    subplot(3, 1, (n_dir-1)*2 + n_stg);
    title(['F ', dirs{n_dir}, ' to ', stages{n_stg}, ' ', dirs{n_dir}]);
    hold on;
    plot(freqs, abs(squeeze(FRFs_CoM(6*(n_stg+4) + n_dir, n_dir, :)))./((2*pi*freqs).^2)');
    plot(f, abs(squeeze(freqresp(G_ms([stages{n_stg}, '_', dirs{n_dir}], ['F', dirs{n_dir}]), f, 'Hz'))));
    set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log');
    ylabel('Amplitude [m/N]');
    if n_dir == 3
      xlabel('Frequency [Hz]');
    end
    hold off;
    xlim([10, 1000]);
    ylim([1e-12, 1e-6]);
  end
end

identification_comp_top_stages.png

Figure 3: caption (png, pdf)

4 Other analysis

4.1 Plot the obtained transfer functions

4.2 Compare with the modal measurements

4.3 Modal Identification of the micro station

Author: Dehaeze Thomas

Created: 2019-12-12 jeu. 13:54

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