A very simple spacecraft with thrusters and one sensor.

This model is used in the demo REAControl. REA stands for Rocket Engine
Assembly, i.e. thrusters. The thrusters are defined by their position in
the body frame, r, and their thrust unit vector, u.
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See also BuildCADModel, CreateBody, CreateComponent, QLVLH,
FindDirectory, SaveStructure
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Contents

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

clear mass

Data

%------
r                  = 7000;
v                  = sqrt(3.98600436e5/r);
rECI               = [r;0;0];
vECI               = [0;v;0];
qLVLH              = QLVLH( rECI, vECI );
q                  = [1;0;0;0];
omega              = [0;-v/r;0];

% Core box
%---------
coreX              = 1.0;
coreY              = 1.0;
coreZ              = 1.0;
corePosition       = [0; 0; 0];

% Star tracker
%-------------
sTBoresight  = [0;0;1];
sTLoc        = [0.4;0.4;0.4];

% Set mass properties
%--------------------
mass.mass    = 20;
mass.cM      = [0;0;0];
mass.inertia = 10/3*eye(3);

Initialize

%-----------
BuildCADModel( 'initialize' );

% Add spacecraft properties
%--------------------------
BuildCADModel( 'set name' ,      'REA Satellite' );
BuildCADModel( 'set units',      'mks'   );
BuildCADModel( 'set rECI' ,       rECI   );
BuildCADModel( 'set vECI' ,       vECI   );
BuildCADModel( 'set qLVLH',       qLVLH  );
BuildCADModel( 'set qECIToBody',  q      );
BuildCADModel( 'set omega',       omega  );
BuildCADModel( 'set mass',        mass   );

Create bodies first

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

% Core
%-----
m = CreateBody( 'make', 'name', 'Core' );
BuildCADModel('add body', m );

% This creates the connections between the bodies
%------------------------------------------------
BuildCADModel( 'compute paths' );

Add Components

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

% Core
%-----------------------------------------------------------------------------------------------
m = CreateComponent( 'make', 'box', 'x', coreX, 'y', coreY, 'z', coreZ,...
                     'faceColor', 'gold foil','inside',0,...
                     'rA', corePosition, 'mass', 10, 'name', 'Panels', 'body', 1 );
BuildCADModel( 'add component', m );

% Star Camera
%--------------
m = CreateComponent( 'make', 'camera', 'model', 'ct633',...
                     'unitVector', sTBoresight,'inside',0,...
                     'rA', sTLoc, 'name', 'Camera', 'body', 1, 'faceColor', 'aluminum' );
BuildCADModel( 'add component', m );

% Thrusters
%----------
thrust = ones(1,24);

clear r

xPos1 = [ 0.5,  0.5,  0.5]; xPos2 = [ 0.5,  0.5, -0.5]; xPos3 = [ 0.5, -0.5, -0.5]; xPos4 = [ 0.5, -0.5,  0.5];
yPos1 = [ 0.5,  0.5,  0.5]; yPos2 = [-0.5,  0.5,  0.5]; yPos3 = [-0.5,  0.5, -0.5]; yPos4 = [ 0.5,  0.5, -0.5];
zPos1 = [ 0.5,  0.5,  0.5]; zPos2 = [ 0.5, -0.5,  0.5]; zPos3 = [-0.5, -0.5,  0.5]; zPos4 = [-0.5,  0.5,  0.5];
xNeg1 = [-0.5,  0.5,  0.5]; xNeg2 = [-0.5,  0.5, -0.5]; xNeg3 = [-0.5, -0.5, -0.5]; xNeg4 = [-0.5, -0.5,  0.5];
yNeg1 = [ 0.5, -0.5,  0.5]; yNeg2 = [-0.5, -0.5,  0.5]; yNeg3 = [-0.5, -0.5, -0.5]; yNeg4 = [ 0.5, -0.5, -0.5];
zNeg1 = [ 0.5,  0.5, -0.5]; zNeg2 = [ 0.5, -0.5, -0.5]; zNeg3 = [-0.5, -0.5, -0.5]; zNeg4 = [-0.5,  0.5, -0.5];

r = [xPos1; xPos2; xPos3; xPos4;...
     yPos1; yPos2; yPos3; yPos4;...
     zPos1; zPos2; zPos3; zPos4;...
     xNeg1; xNeg2; xNeg3; xNeg4;...
     yNeg1; yNeg2; yNeg3; yNeg4;...
     zNeg1; zNeg2; zNeg3; zNeg4]';

u   = -[[ 1,  0,  0];  [ 1,  0,  0]; [ 1,  0,  0]; [ 1,  0,  0];...
        [ 0,  1,  0];  [ 0,  1,  0]; [ 0,  1,  0]; [ 0,  1,  0];...
        [ 0,  0,  1];  [ 0,  0,  1]; [ 0,  0,  1]; [ 0,  0,  1];...
        [-1,  0,  0];  [-1,  0,  0]; [-1,  0,  0]; [-1,  0,  0];...
        [ 0, -1,  0];  [ 0, -1,  0]; [ 0, -1,  0]; [ 0, -1,  0];...
        [ 0,  0, -1];  [ 0,  0, -1]; [ 0,  0, -1]; [ 0,  0, -1]]';

type   = 'mr-103c';
for k = 1:length(thrust)
  m         = CreateComponent( 'make', 'hydrazine thruster', 'model', type, 'name', sprintf('Thruster %i',k),...
                               'body', 1, 'rA', r(:,k), 'unitVector', u(:,k), ...
                               'thrust', thrust(k), 'positionVector', r(:,k), ...
                               'pressureNominal',350*6895,'inside',0);
  BuildCADModel( 'add component', m );
end

Get finished model and display

%--------------------------------
g = BuildCADModel( 'get cad model' );
BuildCADModel('show spacecraft');
dName = FindDirectory('SCModels');
SaveStructure( g, fullfile(dName,'SatWThrusters') )


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

Published with MATLAB® R2019a