ssts__plot_orbit_position3d.m

空间绳系卫星的仿真软件

function [ error_status ] = SSTS__plot_orbit_position3d( distance_to_periapsis ,orbits, step )

% /*M-FILE FUNCTION SSTS__plot_orbit_position3d MMM SSTSLAB */
% /*==================================================================================================
%  Simple Space Tether Simulation Laboratory Toolbox for Matlab 7.x
%
%  Copyright 2007 The SxLAB Family - Yi Chen - [e-mail]
% ====================================================================================================
%File description:
%       To plot the position function of orbits( cycles ) as following:
%       R(theta) = rp*(1+e)/(1+e*cos(theta))
%            where,
%                  rp - distance to periapsis, 6890km in default
%                   e - the magnitude of the eccentricity vector,which belong to [0,1]
% Input:
%  distance_to_periapsis -- the distance to periapsis or rp
%  orbits                -- cycles numbers,  default 5
%  step                  -- simulations step,default 0.01
%
% Output:
%  error_status =  0     -- ok
%                 !0     -- fail
% Example :
%
% >> SSTS__plot_orbit_position3d(7000)
%
% ans =
%
%      0
%===================================================================================================
%  See Also:    SSTS__plot_orbit_position
%
%===================================================================================================
%
%===================================================================================================
%Revision -
%Date        Name    Description of Change email                 Location
%27-Nov-2006 Yi Chen Initial version       [e-mail] Glasgow
%HISTORY$
%==================================================================================================*/

% SSTS__plot_orbit_position3d Begin

error_status = 0;
%% check input & error protect
if ( nargin == 0 )

    step                  = 0.01;
    orbits                = 5.0 ;
    distance_to_periapsis = 6890;%km

elseif( nargin == 1 ) % step in default

    step                  = 0.01;
    orbits                = 5.0 ;

elseif( nargin == 2 ) % step in default

    step                  = 0.01;
    orbits                = 5.0 ;

elseif( nargin == 3 ) % step in default

    step                  = 0.01;

elseif( nargin > 4 ) % step in default

    error ('SSTS__plot_orbit_position3d() Error: Input Parameters...');

    error_status = 1 ;

end

eccentricity = 0:step:1;
theta        = 0:step:orbits*2*pi;

length_of_position       = zeros(length(theta),length(eccentricity));

% calculating position

for jdx = 1 : 1 : length(eccentricity)
    for idx = 1 : 1 : length(theta)

        length_of_position(idx,jdx) = (distance_to_periapsis*(1+eccentricity(jdx)))./(1+eccentricity(jdx)*cos(theta(idx)));

    end
end

%plot
meshz(eccentricity,theta/2/pi,length_of_position);
colormap hsv

%X,Y,Z axis
xlabel('Eccentricity(e:0~1)');
ylabel('Orbits(cycles)');
zlabel('Position Length(km)');
title( 'R(\theta)=rp(1+e)/(1+ecos(\theta)');


% SSTS__plot_orbit_position3d End