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Analysis of the force sensor stiffness

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Thomas Dehaeze 2021-03-12 20:08:09 +01:00
parent b4c03be3ef
commit 8f729963ee
5 changed files with 280 additions and 229 deletions
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@ -1044,7 +1044,6 @@ addpath('./matlab/');
addpath('./mat/');
#+end_src
*** Analysis :ignore:
Let's load the measurement data.
@ -1115,7 +1114,7 @@ exportFig('figs/force_noise_asd.pdf', 'width', 'wide', 'height', 'normal');
[[file:figs/force_noise_asd.png]]
** TODO Force Sensor Stiffness
** Force Sensor Stiffness
*** Introduction :ignore:
The objective of this measurement is to estimate the stiffness of the force sensor [[file:doc/A700000007147087.pdf][FC2231-0000-0010-L]].
@ -1157,25 +1156,56 @@ addpath('./mat/');
Let's load the measured force as well as the measured displacement.
#+begin_src matlab
%% Load measurement data
load('force_sensor_stiff_meas.mat', 't', 'F', 'd')
load('force_sensor_stiffness_meas.mat', 't', 'F', 'd')
#+end_src
Some pre-processing is applied on the data.
#+begin_src matlab
%% Remove offset
F = F - mean(F(t > 0.5 & t < 1.0));
%% Select important part of data
F = F( t > 1.55 & t < 4.65);
d = d( t > 1.55 & t < 4.65);
F = F( t > 4.55 & t < 7.24);
d = d( t > 4.55 & t < 7.24); d = d - d(1);
t = t( t > 4.55 & t < 7.24);
#+end_src
The linear fit is performed.
#+begin_src matlab
%% Linear fit
fit_k = polyfit(F, d, 1);
#+end_src
#+begin_src matlab
%% Force Sensor Stiffness
fit_k(1)
The displacement as a function of the force as well as the linear fit are shown in Figure [[fig:force_sensor_stiffness_fit]].
#+begin_src matlab :exports none
figure;
hold on;
plot(F, 1e6*d, '-', 'DisplayName', 'Raw Data');
plot(F([1,end]), 1e6*(F([1,end])*fit_k(1) + fit_k(2)), '--', 'DisplayName', 'Line Fit');
hold off;
xlabel('Force [$N$]'); ylabel('Displacement [$\mu m$]');
xlim([0,45]); ylim([0,60]);
legend('location', 'southeast');
#+end_src
#+begin_src matlab :tangle no :exports results :results file replace
exportFig('figs/force_sensor_stiffness_fit.pdf', 'width', 'wide', 'height', 'normal');
#+end_src
#+name: fig:force_sensor_stiffness_fit
#+caption: Displacement as a function of the measured force
#+RESULTS:
[[file:figs/force_sensor_stiffness_fit.png]]
And we obtain the following stiffness:
#+begin_src matlab :results value replace :exports results
%% Force Sensor Stiffness
sprintf('k = %.2f [N/um]', 1e-6*1/fit_k(1));
#+end_src
#+RESULTS:
: k = 0.76 [N/um]
* Bending Stiffness Measurement
:PROPERTIES:
:header-args:matlab+: :tangle ./matlab/bending_stiff_meas.m

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