Demonstrates how to use the thermal modeling package

The spacecraft is a cube with two solar wings. The model includes solar and planetary fluxes including albedo and radiation. The demo draws two parallel camera views, one visible and one indicating the temperatures.

SpacecraftThermal computes the temperatures from the thermal model and ThermalImager assigns display colors to each component in the CAD model. ------------------------------------------------------------------------ See also SpaceCamera, SpacecraftThermal, ThermalImager, PlotThermal, DrawSCPlanPlugIn, QForm, QLVLH, QPose, TimeGUI, FindSolsticeOrEquinox, RVFromKepler, SolarFlx, SunV1, AutoPoint, CameraDatabase ------------------------------------------------------------------------

Contents

%-------------------------------------------------------------------------------
%   Copyright (c) 1998-2003, 2007 Princeton Satellite Systems, Inc.
%   All rights reserved.
%-------------------------------------------------------------------------------

Load the CAD model

%-------------------
g = load('SCForImaging');
DrawSCPlanPlugIn(g);

% Initial rotation of solar arrays
%---------------------------------
g.body(2).bHinge.angle = 0;
g.body(2).bHinge.axis  = 2;
g.body(3).bHinge.angle = 0;
g.body(3).bHinge.axis  = 2;

Set up the simulation

%-----------------------
global simulationAction
simulationAction = 'Do Nothing';

% Ephemeris
%----------
jD0   = FindSolsticeOrEquinox('spring equinox',2002);
nDays = 2;
nSamp = 300;
t     = linspace(0,nDays,nSamp)*86400;
jD    = jD0 + t/86400;
dTSim = t(2)-t(1);

% Spacecraft orbit (GEO)
%-----------------------
[rECI, vECI] = RVFromKepler( [42167 0 0 0 0 0], t );

% Camera
%-------
camera                  = CameraDatabase('256 square');
camera.up               = [0;-1;0];
camera.focalLength      = 0.05;

% Initialize the picture in SpaceCamera
%--------------------------------------
% The optical camera
qECIToLVLH              = QLVLH( rECI(:,1), vECI(:,1) );
g.body(1).bHinge.q      = QPose(qECIToLVLH);
g.rECI                  = rECI(:,1);
g.qLVLH                 = qECIToLVLH;
g.name                  = 'Satellite';
d                       = struct('position',[]);
d.planetName            = 'Earth';
d.camera                = camera;
tagVisibleCameraWindow  = SpaceCamera( 'initialize', d, g, jD(1) );

% The thermal camera
%-------------------
figH = findobj( 'tag', tagVisibleCameraWindow );
h    = get( figH, 'UserData' );
d.position              = get(h.fig3D,'position') + [camera.xPixels 0 0 0];
d.planetName            = 'Earth';
d.camera                = camera;
d.imagerFunction        = @ThermalImager;
d.colorMap              = hot;
d.tempMax               = 700;
g.temperature           = 300*ones(length(g.component),1);
d.name                  = 'SpaceThermalCamera';
tagInfraredCameraWindow = SpaceCamera( 'initialize', d, g, jD(1) );
SpaceCamera('set ambient',tagInfraredCameraWindow,0.5);

% Environment data for thermal temperature model
%-----------------------------------------------
e = struct;
flux0                   = SolarFlx(1);
e.planet                = 'earth';
e.planetRadius          = 6378.165;
e.s                     = flux0*SunV1(jD(1)); % Watts/m^2
e.tSamp                 = dTSim;
e.shadow                = false;
e.showScans             = false;
e.nScanLines            = 10;
e.units                 = 'm';

% Initialize the flux and temperature arrays
%-------------------------------------------
q    = zeros(length(g.component),nSamp);
temp = zeros(length(g.component),nSamp);

% Now run the simulation
%-----------------------
qLVLHToBody = Mat2Q([0 0 -1;0 1 0;1 0 0]);

[ ratioRealTime, tToGoMem ] =  TimeGUI( nSamp, 0 );

Loop through the disturbances

%-------------------------------
for k = 1:nSamp

  [ ratioRealTime, tToGoMem ] = TimeGUI( nSamp, k, tToGoMem, ratioRealTime, dTSim );

  % Update solar ephemeris
  %-----------------------
  [uSun, rSun] = SunV1(jD(k));
  e.s          = flux0*uSun;
  e.r          = rECI(:,k);
  e.v          = vECI(:,k);
  e.rSun       = rSun*uSun;

  % Sun vector
  %-----------
  qLVLH    = QLVLH( rECI(:,k), vECI(:,k) );
  uSunLVLH = QForm( qLVLH, uSun );
  theta    = atan2( uSunLVLH(1), uSunLVLH(3) );

  % CAD body structure
  %-------------------
  g.body(1).bHinge.q     = QPose(QMult(qLVLH,qLVLHToBody));
  g.body(2).bHinge.angle = theta;
  g.body(3).bHinge.angle = theta;
  g.rECI                 = rECI(:,k);
  g.qLVLH                = qLVLH;

  % Update the temperature
  %-----------------------
  p = SpacecraftThermal( 'run', g, e );

  % Draw the picture
  %-----------------
  [qCamera,rCamera,distance] = AutoPoint( 'above', camera, g );
  camera.rBody    = rCamera;
  camera.qBody    = qCamera;
  camera.distance = distance;
  g.temperature   = p.temperature;

  SpaceCamera( 'update camera',     tagVisibleCameraWindow,  camera, jD(k) );
  SpaceCamera( 'update spacecraft', tagVisibleCameraWindow,  g,      jD(k) );
  SpaceCamera( 'update camera',     tagInfraredCameraWindow, camera, jD(k) );
  SpaceCamera( 'update spacecraft', tagInfraredCameraWindow, g,      jD(k) );

  % For the plots
  %--------------
  q(:,k)    = p.qTotal;
  temp(:,k) = p.temperature;

  % TimeGUI control
  %-----------------
  switch simulationAction
    case 'pause'
      pause
      simulationAction = ' ';
    case 'stop'
      return;
    case 'plot'
      break;
  end
end

Plot the results

PlotThermal( q(:,1:k), temp(:,1:k), t(1:k), g );

%--------------------------------------

% $Id: eaffa369a08780e21c4683af32e10f9a100c9c83 $

Published with MATLAB® R2024a