diff --git a/org/noise_budgeting.org b/org/noise_budgeting.org new file mode 100644 index 0000000..8717840 --- /dev/null +++ b/org/noise_budgeting.org @@ -0,0 +1,242 @@ +#+TITLE: Noise Budgeting +#+SETUPFILE: ./setup/org-setup-file.org + +* Maximum Noise of the Relative Motion Sensors +** Matlab Init :noexport:ignore: +#+begin_src matlab :tangle no :exports none :results silent :noweb yes :var current_dir=(file-name-directory buffer-file-name) + <> +#+end_src + +#+begin_src matlab :exports none :results silent :noweb yes + <> +#+end_src + +#+BEGIN_SRC matlab + simulinkproject('../'); +#+END_SRC + +** Initialization +#+begin_src matlab + open('nass_model.slx'); +#+end_src + +#+begin_src matlab + initializeGround(); + initializeGranite(); + initializeTy(); + initializeRy(); + initializeRz(); + initializeMicroHexapod(); + initializeAxisc(); + initializeMirror(); + + initializeSimscapeConfiguration(); + initializeDisturbances('enable', false); + initializeLoggingConfiguration('log', 'none'); + + initializeController('type', 'hac-dvf'); +#+end_src + +We set the stiffness of the payload fixation: +#+begin_src matlab + Kp = 1e8; % [N/m] +#+end_src + +#+begin_src matlab + initializeNanoHexapod('k', 1e5, 'c', 2e2); + + Ms = 50; + initializeSample('mass', Ms, 'freq', sqrt(Kp/Ms)/2/pi*ones(6,1)); +#+end_src + +#+begin_src matlab + initializeReferences('Rz_type', 'rotating-not-filtered', 'Rz_period', Ms); +#+end_src + +** Control System +#+begin_src matlab + Kdvf = 5e3*s/(1+s/2/pi/1e3)*eye(6); +#+end_src + +#+begin_src matlab + h = 2.0; + Kl = 2e7 * eye(6) * ... + 1/h*(s/(2*pi*100/h) + 1)/(s/(2*pi*100*h) + 1) * ... + 1/h*(s/(2*pi*200/h) + 1)/(s/(2*pi*200*h) + 1) * ... + (s/2/pi/10 + 1)/(s/2/pi/10) * ... + 1/(1 + s/2/pi/300); +#+end_src + +#+begin_src matlab + load('mat/stages.mat', 'nano_hexapod'); + K = Kl*nano_hexapod.kinematics.J*diag([1, 1, 1, 1, 1, 0]); +#+end_src + +#+begin_src matlab :exports none + %% Name of the Simulink File + mdl = 'nass_model'; + + %% Micro-Hexapod + clear io; io_i = 1; + io(io_i) = linio([mdl, '/Noises'], 1, 'openinput', [], 'ndL'); io_i = io_i + 1; + io(io_i) = linio([mdl, '/Tracking Error'], 1, 'output', [], 'En'); io_i = io_i + 1; +#+end_src + +#+begin_src matlab + %% Run the linearization + G = linearize(mdl, io); + G.InputName = {'ndL1', 'ndL2', 'ndL3', 'ndL4', 'ndL5', 'ndL6'}; + G.OutputName = {'Ex', 'Ey', 'Ez', 'Erx', 'Ery', 'Erz'}; +#+end_src + +#+begin_src matlab :exports none + freqs = logspace(0, 3, 1000); + + figure; + hold on; + plot(freqs, abs(squeeze(freqresp(G(1, 1), freqs, 'Hz')))); + plot(freqs, abs(squeeze(freqresp(G(2, 2), freqs, 'Hz')))); + plot(freqs, abs(squeeze(freqresp(G(3, 3), freqs, 'Hz')))); + plot(freqs, abs(squeeze(freqresp(G(4, 4), freqs, 'Hz')))); + plot(freqs, abs(squeeze(freqresp(G(6, 5), freqs, 'Hz')))); + plot(freqs, abs(squeeze(freqresp(G(6, 6), freqs, 'Hz')))); + hold off; + set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log'); + ylabel('Amplitude [m/m]'); set(gca, 'XTickLabel',[]); +#+end_src + +** Maximum induced vibration's ASD +Required maximum induced ASD of the sample's vibration due to the relative motion sensor noise. +\[ \bm{\Gamma}_x(\omega) = \begin{bmatrix} \Gamma_x(\omega) & \Gamma_y(\omega) & \Gamma_{R_x}(\omega) & \Gamma_{R_y}(\omega) \end{bmatrix} \] + +#+begin_src matlab + Gamma_x = [(1e-9)/(1 + s/2/pi/100); % Dx + (1e-9)/(1 + s/2/pi/100); % Dy + (1e-9)/(1 + s/2/pi/100); % Dz + (2e-8)/(1 + s/2/pi/100); % Rx + (2e-8)/(1 + s/2/pi/100)]; % Ry +#+end_src + +#+begin_src matlab + freqs = logspace(0, 3, 1000); +#+end_src + +Corresponding RMS value in [nm rms, nrad rms] +#+begin_src matlab :exports results :results value table replace :tangle no :post addhdr(*this*) + data2orgtable([1e9*sqrt(trapz(freqs, (abs(squeeze(freqresp(Gamma_x, freqs, 'Hz')))').^2))]', {'Dx [nm]', 'Dy [nm]', 'Dz [nm]', 'Rx [nrad]', 'Ry [nrad]'}, {'Specifications'}, ' %.1f '); +#+end_src + +#+RESULTS: +| | Specifications | +|-----------+----------------| +| Dx [nm] | 12.1 | +| Dy [nm] | 12.1 | +| Dz [nm] | 12.1 | +| Rx [nrad] | 241.8 | +| Ry [nrad] | 241.8 | + +** Computation of the maximum relative motion sensor noise +Let's note $G$ the transfer function from the 6 sensor noise $n$ to the 5dof pose error $x$. +We have: +\[ x_i = \sum_{j=1}^6 G_{ij}(s) n_j, \quad i = 1 \dots 5 \] +In terms of ASD: +\[ \Gamma_{x_i}(\omega) = \sqrt{\sum_{j=1}^6 |G_{ij}(j\omega)|^2 \cdot {\Gamma_{n_j}}^2(\omega)}, \quad i = 1 \dots 5 \] + +Let's suppose that the ASD of all the sensor noise are equal: +\[ \Gamma_{n_j} = \Gamma_{n}, \quad j = 1 \dots 6 \] + +We then have an upper bound of the sensor noise for each of the considered motion errors: +\[ \Gamma_{n_i, \text{max}}(\omega) = \frac{\Gamma_{x_i}(\omega)}{\sqrt{\sum_{j=1}^6 |G_{ij}(j\omega)|^2}}, \quad i = 1 \dots 5 \] + +#+begin_src matlab + Gamma_ndL = zeros(5, length(freqs)); + for in = 1:5 + Gamma_ndL(in, :) = abs(squeeze(freqresp(Gamma_x(in), freqs, 'Hz')))./sqrt(sum(abs(squeeze(freqresp(G(in, :), freqs, 'Hz'))).^2))'; + end +#+end_src + +#+begin_src matlab :exports none + figure; + hold on; + for in = 1:5 + plot(freqs, Gamma_ndL(in, :), 'k-'); + end + hold off; + set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log'); + xlabel('Frequency [Hz]'); ylabel('ASD [$\frac{m}{\sqrt{Hz}}$]'); +#+end_src + +#+begin_src matlab :tangle no :exports results :results file replace + exportFig('figs/noise_budget_ndL_max_asd.pdf', 'width', 'wide', 'height', 'normal'); +#+end_src + +#+name: fig:noise_budget_ndL_max_asd +#+caption: Maximum estimated ASD of the relative motion sensor noise +#+RESULTS: +[[file:figs/noise_budget_ndL_max_asd.png]] + +If the noise ASD of the relative motion sensor is bellow the maximum specified ASD for all the considered motion: +\[ \Gamma_n < \Gamma_{n_i, \text{max}}, \quad i = 1 \dots 5 \] +Then, the motion error due to sensor noise should be bellow the one specified. + +#+begin_src matlab + Gamma_ndL_max = min(Gamma_ndL(1:5, :)); +#+end_src + +Let's take a sensor with a white noise up to 1kHz that is bellow the specified one: +#+begin_src matlab + Gamma_ndL_ex = abs(squeeze(freqresp(min(Gamma_ndL_max)/(1 + s/2/pi/1e3), freqs, 'Hz'))); +#+end_src + +#+begin_src matlab :exports none + figure; + hold on; + plot(freqs, Gamma_ndL_max, 'k-', 'DisplayName', 'Specification'); + plot(freqs, Gamma_ndL_ex, 'DisplayName', 'Sensor Example'); + hold off; + set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log'); + xlabel('Frequency [Hz]'); ylabel('ASD [m/sqrt(Hz)]'); +#+end_src + +#+begin_src matlab :tangle no :exports results :results file replace + exportFig('figs/relative_motion_sensor_noise_ASD_example.pdf', 'width', 'wide', 'height', 'normal'); +#+end_src + +#+name: fig:relative_motion_sensor_noise_ASD_example +#+caption: Requirement maximum ASD of the sensor noise + example of a sensor validating the requirements +#+RESULTS: +[[file:figs/relative_motion_sensor_noise_ASD_example.png]] + +The corresponding RMS value of the sensor noise taken as an example is [nm RMS]: +#+begin_src matlab :results replace value + 1e9*sqrt(trapz(freqs, Gamma_ndL_max.^2)) +#+end_src + +#+RESULTS: +: 519.29 + +** Verification of the induced motion error +Verify that by taking the sensor noise, we have to wanted displacement error +From the sensor noise PSD $\Gamma_n(\omega)$, we can estimate the obtained displacement PSD $\Gamma_x(\omega)$: +\[ \Gamma_{x,i}(\omega) = \sqrt{ \sum_{j=1}^{6} |G_{ij}|^2(j\omega) \cdot \Gamma_{n,j}^2(\omega) }, \quad i = 1 \dots 5 \] + +#+begin_src matlab + Gamma_xest = zeros(5, length(freqs)); + + for in = 1:5 + Gamma_xest(in, :) = sqrt(sum(abs(squeeze(freqresp(G(in, :), freqs, 'Hz'))).^2.*Gamma_ndL_max.^2)); + end +#+end_src + +#+begin_src matlab :exports results :results value table replace :tangle no :post addhdr(*this*) + data2orgtable([1e9*sqrt(trapz(freqs, (Gamma_xest.^2)')); 1e9*sqrt(trapz(freqs, (abs(squeeze(freqresp(Gamma_x, freqs, 'Hz')))').^2))]', {'Dx [nm]', 'Dy [nm]', 'Dz [nm]', 'Rx [nrad]', 'Ry [nrad]'}, {'Results', 'Specifications'}, ' %.1f '); +#+end_src + +#+RESULTS: +| | Results | Specifications | +|-----------+---------+----------------| +| Dx [nm] | 8.9 | 12.1 | +| Dy [nm] | 9.3 | 12.1 | +| Dz [nm] | 10.2 | 12.1 | +| Rx [nrad] | 110.2 | 241.8 | +| Ry [nrad] | 107.8 | 241.8 |