Contents

Optical navigation demo in the solar system

Simulates optical navigation in the solar system.

%--------------------------------------------------------------------------
%  See also:  NavigationCameraSunStar, StarCameraViewer,
%             OpticalNavigationSun
%--------------------------------------------------------------------------

%--------------------------------------------------------------------------
%   Copyright (c) 2020 Princeton Satellite Systems, Inc.
%   All rights reserved.
%--------------------------------------------------------------------------
%   Since 2020.2
%--------------------------------------------------------------------------

Constants

aU        = Constant('au');
mu        = Constant('mu sun');
dayToSec  = 86400;
dayInYear = 365.25;
secInYear = dayToSec*dayInYear;

Viewers slow the simulation down

viewersOn = true;

User inputs

       [semi-najor axis, inclination, ascending node, argument of
       perigee, eccentricity, mean anomaly]

t       = linspace(0,1e7);
el      = [3*aU 0 0 0 0.8 0]; % For hyperbolic orbit e > 1 a must be negative
[r,v]   = RVOrbGen(el,t,[],mu);
jD0     = Date2JD([2023 4 5]);

Julian date vector

n       = length(t);
jD      = jD0 + t/dayToSec;

Setup the camera

d       = NavigationCameraSunStar;

Set up the viewer

if( viewersOn )
  hNav = StarCameraViewer('initialize','Navigation Camera',n); %#ok<*UNRCH>
end

Set up Optical Navigation

dONS    = OpticalNavigationSun;
dONS.dT = t(2);

OpticalNavigationSun( 'initialize', dONS, r(:,1), v(:,1) );
yN      = NavigationCameraSunStar( r(:,1), [1;0;0;0], d );
dONS    = OpticalNavigationSun( 'get unit vector', dONS, r(:,1), jD(1) );
dONS    = OpticalNavigationSun( 'update', dONS, yN, r(:,1) );

Size the arrays

rE      = r;
vE      = v;
nStars  = zeros(1,n);

Simulate

for k = 1:n
  if( k > 1 )
    dONS.dT = t(k) - t(k-1);
  else
    dONS.dT = t(2);
  end

  dONS      = OpticalNavigationSun( 'get unit vector', dONS, r(:,k), jD(k) );

  q         = U2Q(dONS.u,[0;0;1]);
  yN        = NavigationCameraSunStar( r(:,k), q, d );

  % ONS
  [dONS,rE(:,k),vE(:,k)] = OpticalNavigationSun( 'update', dONS, yN, r(:,k) );
  nStars(k) = dONS.nStars;

  % Display the cameras
  if( viewersOn )
    StarCameraViewer('update',yN,[],hNav, d,k);
  end
end

Plot the results

% Heliocentric
rECI = zeros(3,n);
for k = 1:n
  rECI(:,k) = CEcl2Eq( jD(k) )*r(:,k);
end

HelioPlot(3:5,t(end)/secInYear,jD0,rECI,{'Spacecraft'});

% Position and velocity
[t,tL]    = TimeLabl(t);
yL        = {'r_x (km)'   'r_y (km)'    'r_z (km)' };
vL        = {'v_x (km/s)' 'v_y (km/s)'  'v_z (km/s)' };
legX      = {'True' 'Estimate'};
leg       = { legX legX legX };

Plot2D(t,[r;rE],tL,yL,'Position','lin',{'[1 4]','[2 5]','[3 6]'},[],[],[],[],leg)
Plot2D(t,[v;vE],tL,vL,'Velocity','lin',{'[1 4]','[2 5]','[3 6]'},[],[],[],[],leg)

Figui

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

Published with MATLAB® R2020a