Implements and simulates a spacecraft with 3 orthogonal reaction wheels.

The spacecraft is given an external disturbance in the x axis. The
function 'RHSRWASC' is used for the right-hand-side of the numerical
integration.

This also shows how to use the time display.

------------------------------------------------------------------------- See also RHSRWASC and ReactionWheel., Plot2D, TimeGUI, TimeLabl, RK4 -------------------------------------------------------------------------

Global for the time interface
Sim data
Initialize the reaction wheel model with the data stored in the model
Spacecraft data
Initial state
Put the state together
Initialize the time display
Allocate memory for arrays
Run the simulation
Adjust the arrays if you quit early
Plot

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

Global for the time interface

%-------------------------------
global simulationAction
simulationAction = ' ';

Sim data

%----------
nSim  = 1000;
dTSim = 0.25;

Initialize the reaction wheel model with the data stored in the model

%-----------------------------------------------------------------------
ReactionWheel('initialize');

Spacecraft data

%-----------------
d          	= ReactionWheel('get default datastructure');
sim.inertia	= diag([100 80 150]);
sim.inrRWA  = d.inertia;
sim.mu    	= 3.98600436e5;
sim.tDist 	= [0.1;0;0]; % External disturbance

Initial state

%---------------
rECI        = [6578;0;0];
vECI        = [0;sqrt(sim.mu/rECI(1));0];
qECIToBody  = [1;0;0;0];
w           = [0;0;0];
wRWA        = [0;0;0];
angleRWA    = [0;0;0];
frictionRWA = [0;0;0];

Put the state together

%------------------------
x           = [rECI;vECI;qECIToBody;w;angleRWA;wRWA;frictionRWA];
t           = 0;

Initialize the time display

%-----------------------------
[ratioRealTime, tToGoMem] =  TimeGUI( nSim, 0, [], 0, dTSim, 'Spacecraft with Reaction Wheels' );

Allocate memory for arrays

%----------------------------
tPlot = zeros( 1,nSim);
xPlot = zeros(22,nSim);

Run the simulation

-------------------

for k = 1:nSim

  % Display the status message
  %---------------------------
  [ ratioRealTime, tToGoMem ] = TimeGUI( nSim, k, tToGoMem, ratioRealTime, dTSim );

  % Integrate one step
  %-------------------
  x          = RK4('RHSRWASC', x, dTSim, t, sim );
  t          = t + dTSim;

  % Store for plotting
  %-------------------
  tPlot(k)   = t;
  xPlot(:,k) = x;

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

end

Adjust the arrays if you quit early

%-------------------------------------
j           = 1:k;
xPlot       = xPlot(:,j);
[tPlot, c ] = TimeLabl( tPlot(j) );

Plot

%------
Plot2D( tPlot, xPlot( 1: 3,:), c, ['Rx';'Ry';'Rz'],      'Position'             )
Plot2D( tPlot, xPlot( 4: 6,:), c, ['Vx';'Vy';'Vz'],      'Velocity'             )
Plot2D( tPlot, xPlot( 7:10,:), c, ['Qs';'Qx';'Qy';'Qz'], 'Quaternion'           )
Plot2D( tPlot, xPlot(11:13,:), c, ['Wx';'Wy';'Wz'],      'Body Rates'           )
Plot2D( tPlot, xPlot(17:19,:), c, ['W1';'W2';'W3'],      'Reaction Wheel Rates' )


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