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ex_Earth_CAVH.m
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ex_Earth_CAVH.m
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% ----------------------------------------------------------------------- %
% problem formulation for the atmospheric entry phase of the
% robotic Earth EDL mission, CAV-H
% Main reference: Lu, AIAA GNC conference 2013-4648
%
% Coded by Dr. Youngro Lee* for his PhD work under the supervision of
% Prof. Dae Young Lee** and Prof. Bong Wie***
% Iowa State University, Ames, IA 50011
% ***[email protected]
% ----------------------------------------------------------------------- %
% constants
rp = 6378.137e3; % Earth radius, m
mu = 398600.435507e9; % gravitational parameter, m^3/s^2
w = 2*pi/86400; % spin rate, rad/s
d2r = pi/180;
r2d = 180/pi;
% planet / 1: Earth, 2: Mars
pn = 1;
% vehicle parameters (Phillips 2003)
S = 0.4839; % cross-sectional area, m^2
m = 907; % mass, kg
CL = 0.42324; % lift cofficient, mean value
CD = 0.1292; % drag cofficient, mean value
% entry interface in planet-centered-rotating frame (Lu 2013)
% no need to tranform the coordinate
r0 = rp + 122e3;
theta0 = -72.2744*d2r;
phi0 = 39.1814*d2r;
V0 = 7400;
gamma0 = -1*d2r;
psi0 = 38.5668*d2r;
% final condition
hf = 30e3;
rf = hf + rp;
Vf = 2000;
thetatgt = 64.1166*d2r;
phitgt = 31.4927*d2r;
% path constraints
Amax = 2.5; % g-load, g
qmax = 100; % dynamic pressure, kPa
Qdotmax = 8000; % heating rate, kW/m^2
% heating rate constant
kq = 9.4369e-8;
kqN = 0.5;
kqM = 3.15;
% bank angle constraints
BAL = 1;
siglmt = 90*d2r; % bank magnitude limit
sigdlmt = 15*d2r; % bank rate limit
sigddlmt = 15*d2r; % bank acc limit
% guidance activation time
GAT = 300;
% bank reversal logic
BRL = 1;
dlpsT = [15 5]*d2r;
KBR = 6;
% bank angle parameterization options
if BAP == 1
sig0 = 70*d2r; % initial guess of the parameter to be found
sigf = 60*d2r; % design parameter
sigs = sig0;
auxdata.sigf = sigf;
elseif BAP == 2
sig0 = 70*d2r; % initial guess of the parameter to be found
sigf = 60*d2r; % design parameter
KEF = 0.9; % design parameter
sigs = sig0;
auxdata.sigf = sigf;
auxdata.KEF = KEF;
elseif BAP == 3
sig0 = 70*d2r; % initial guess of the parameter to be found
KEF = 0.6; % design parameter
sigs = sig0;
auxdata.KEF = KEF;
elseif BAP == 4
sig0 = 70*d2r; % initial guess of the parameter to be found
KLF = 0.5; % design parameter
sigs = sig0;
auxdata.KLF = KLF;
end