#+TITLE: Stewart Platform - Simscape Model
:DRAWER:
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#+PROPERTY: header-args:matlab  :session *MATLAB*
#+PROPERTY: header-args:matlab+ :comments org
#+PROPERTY: header-args:matlab+ :exports both
#+PROPERTY: header-args:matlab+ :results none
#+PROPERTY: header-args:matlab+ :eval no-export
#+PROPERTY: header-args:matlab+ :noweb yes
#+PROPERTY: header-args:matlab+ :mkdirp yes
#+PROPERTY: header-args:matlab+ :output-dir figs
:END:

* Introduction                                                        :ignore:

* Parameters used for the Simscape Model

* Simulation Configuration - Configuration reference
As multiple simulink files will be used for simulation and tests, it is very useful to determine good simulation configuration that will be shared among all the simulink files.

This is done using something called "Configuration Reference" ([[https://fr.mathworks.com/help/simulink/ug/more-about-configuration-references.html][documentation]]).

Basically, the configuration is stored in a mat file =conf_simscape.mat= and then loaded in the workspace for it to be accessible to all the simulink models.
It is automatically loaded when the Simulink project is open. It can be loaded manually with the command:
#+begin_src matlab :eval no
  load('mat/conf_simscape.mat');
#+end_src

It is however possible to modify specific parameters just for one Simulink file using the =set_param= command:
#+begin_src matlab :eval no
  set_param(conf_simscape, 'StopTime', 1);
#+end_src

* Subsystem Reference
Several Stewart platform models are used, for instance one is use to study the dynamics while the other is used to apply active damping techniques.

However, all the Simscape models share some subsystems using the *Subsystem Reference* Simulink block ([[https://fr.mathworks.com/help/simulink/ug/referenced-subsystem-1.html][documentation]]).

These shared subsystems are:
- =Fixed_Based.slx= - Fixed base of the Stewart Platform
- =Mobile_Platform.slx= - Mobile platform of the Stewart Platform
- =stewart_strut.slx= - One strut containing two spherical/universal joints, the actuator as well as the included sensors. A parameter =i= is initialized to determine what it the "number" of the strut.

These subsystems are referenced from another subsystem called =Stewart_Platform.slx=, that basically connect them correctly.
This subsystem is then referenced in other simulink models for various purposes.

* Basic configuration for the Fixed base, Mobile Platform and Struts

* Sensors included in the Struts and on the Mobile Platform

* Inertial Sensors
** Z-Axis Geophone
:PROPERTIES:
:header-args:matlab+: :tangle ./src/initializeZAxisGeophone.m
:header-args:matlab+: :comments none :mkdirp yes :eval no
:END:
<<sec:initializeZAxisGeophone>>

This Matlab function is accessible [[file:../src/initializeZAxisGeophone.m][here]].

#+begin_src matlab
  function [geophone] = initializeZAxisGeophone(args)
      arguments
          args.mass (1,1) double {mustBeNumeric, mustBePositive} = 1e-3 % [kg]
          args.freq (1,1) double {mustBeNumeric, mustBePositive} = 1    % [Hz]
      end

      %%
      geophone.m = args.mass;

      %% The Stiffness is set to have the damping resonance frequency
      geophone.k = geophone.m * (2*pi*args.freq)^2;

      %% We set the damping value to have critical damping
      geophone.c = 2*sqrt(geophone.m * geophone.k);

      %% Save
      save('./mat/geophone_z_axis.mat', 'geophone');
  end
#+end_src

** Z-Axis Accelerometer
:PROPERTIES:
:header-args:matlab+: :tangle ./src/initializeZAxisAccelerometer.m
:header-args:matlab+: :comments none :mkdirp yes :eval no
:END:
<<sec:initializeZAxisAccelerometer>>

This Matlab function is accessible [[file:../src/initializeZAxisAccelerometer.m][here]].

#+begin_src matlab
  function [accelerometer] = initializeZAxisAccelerometer(args)
      arguments
          args.mass (1,1) double {mustBeNumeric, mustBePositive} = 1e-3 % [kg]
          args.freq (1,1) double {mustBeNumeric, mustBePositive} = 5e3  % [Hz]
      end

      %%
      accelerometer.m = args.mass;

      %% The Stiffness is set to have the damping resonance frequency
      accelerometer.k = accelerometer.m * (2*pi*args.freq)^2;

      %% We set the damping value to have critical damping
      accelerometer.c = 2*sqrt(accelerometer.m * accelerometer.k);

      %% Gain correction of the accelerometer to have a unity gain until the resonance
      accelerometer.gain = -accelerometer.k/accelerometer.m;

      %% Save
      save('./mat/accelerometer_z_axis.mat', 'accelerometer');
  end
#+end_src